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Post-traumatic syringomyelia (cystic myelopathy): a prospective study of 449 patients with spinal cord injury treatment kitty colds order generic chloromycetin line. Cardiac-gated phase-contrast magnetic resonance imaging of cerebrospinal fluid flow in the diagnosis of idiopathic syringomyelia. Residual deformity of the spinal canal in patients with traumatic paraplegia and secondary changes of the spinal cord. Post-traumatic syringomyelia and post-traumatic spinal canal stenosis: a direct relationship: review of 75 patients with a spinal cord injury. A clinical magnetic resonance imaging study of the traumatised spinal cord more than 20 years following injury. The "presyrinx" state: is there a reversible myelopathic condition that may precede syringomyelia Development of post-traumatic cysts in the spinal cord of rats subjected to severe spinal cord contusion. Review of the secondary injury theory of acute spinal cord trauma with emphasis on vascular mechanisms. Patterns of chronic adhesive arachnoiditis following Myodil myelography: the significance of spinal canal stenosis and previous surgery. High-resolution constructive interference in a steady state imaging of cervicothoracic adhesive arachnoiditis. Hyaluronidase as an adjuvant in the management of tuberculous spinal arachnoiditis. Syringopleural shunt as a rescue procedure in patients with syringomyelia refractory to restoration of cerebrospinal fluid flow. Long-term results and complications of the syringopleural shunting for treatment of syringomyelia: a clinical study. Okonkwo the determination of spinal stability is one of the most important tasks in the evaluation and management of the trauma patient. Recognition of the presence or absence of spinal stability is critical for clinical decision making, not just for guiding operative intervention, but also for informing subacute therapeutic strategies. Despite voluminous literature and evaluation algorithms addressing this topic, the assessment and classification of spinal instability remains a significant challenge, demanding integration of the clinical history, neurological examination, radiographic findings, and a basic understanding of how altered spinal biomechanics and biokinematics will ultimately affect the individual patient. Anatomy A motion segment, or functional spinal unit, represents the principal functional unit of the spine that exhibits biomechanical characteristics similar to those of the entire spine. This may be divided into an anterior structure, forming the vertebral column, and a complex set of posterior structures. The behavior of a motion segment is dependent on the individual properties, interaction, and integrity of these components. The spine should also be considered a structure composed of multiple functional units linked in series, and therefore its total behavior is a composite of these individual units. The most widely accepted general clinical definition of spinal stability is that promulgated by White and Panjabi. Spinal stability is accomplished through the interaction of three subsystems: (1) the vertebrae providing an osseous structural frame; (2) intervertebral disks, apophyseal joints, and ligaments providing dynamic support; and (3) the coordination of muscle response through neural control. The spine may be rendered unstable when sufficient anatomic disruption by trauma or disease severely disrupts any one or a combination of these systems. From the previous definition, it follows that meaningful evaluation and categorization of spinal stability must address both the extent of structural damage as well as functionality under physiologic loads. Spinal injuries should be reliably classified to facilitate communication among treating physicians and to guide management. Vertebrae the twenty-five vertebrae of the spinal column provide the principal support for compressive loads. The vertebrae are composed of highly porous trabecular bone and a dense outer shell. The vertebral end plate provides even distribution and mechanical load transfer as well as prevention of disk extrusion into the porous vertebral body. The importance of the vertebral end plate for maintaining vertebral body integrity increases with decreasing bone density. Biomechanical analysis has demonstrated that under axial compression loading, the first component to fail is the vertebral body because of fracture of the end plates. The posterior elements of the vertebrae include the neural arch, spinous and transverse processes, and articular processes (superior and inferior facets). The neural arch consists of the pedicles and laminae that, together with the posterior wall of the vertebral body, form the borders of the spinal canal. The transverse and spinous processes provide attachment points for the skeletal muscles and ligaments that initiate spine motion. The superior and inferior articular processes of the facet joints constrain intersegmental motion by limiting the extent of torsion and shear. The orientation of the articular processes changes depending on spinal region, with resultant differences in function. The facet (and pars interarticularis) participates in load sharing with the anterior column; in upright, neutral position, 10% to 20% of compressive forces are transmitted through the facet; however, in hyperextension, 30% of compressive loads are transmitted through the facet. Appreciating physiologic spine biomechanics is essential to the management of traumatic injury because it explains the interaction of anatomy under applied forces and movements and predicts the consequences of that interaction. Presented is information helpful in understanding the basic biomechanical function of the spine to permit a systematic IntervertebralDisk Axial load is transferred and distributed through the anterior column through the intervertebral disk. The disk is composed of two parts: an inner, gelatinous nucleus pulposus and an outer, fibrous anulus. The anulus fibrosus contains laminated, fiber bands of alternating directions attached to the osseous tissue at the periphery and to the cartilaginous end plates at the center. Tensile strength of the disk is greater at the anterior and posterior regions and increases under compression. Bending and torsional properties are of great interest because experimental findings suggest it is these, and not compressive loads, that are most damaging to the disk complex. As opposed to compressive loads, torsional loading results in disk failure, a finding exaggerated in degeneration. Although pure compressive loading does not cause herniation, even at high loads and with deliberate anulus injury, combined axial compression, flexion, and lateral bending have been shown to cause disk prolapse. Flexion and lateral bending result in loading conditions that cause a 50% increase in posterior anulus deformation and a considerable increase in nuclear pressure. The transverse portion of the cruciate ligament is the thickest, strongest ligament of the entire spine; the predominant role is restraining translation of the atlas on C2, while permitting axial rotation of the atlas about the dens. The alar ligaments play an important role in restraining rotation and lateral bending between the occiput and atlas and the atlas and axis. These changes are mirrored by the spinal cord, which also changes cross-sectional area (changing from rounder in flexion to more oval on extension). The three meningeal layers (pia mater, arachnoid, and dura mater) and dentate ligaments suspend the spinal cord and also constrain the cord movement (an important consideration during decompressive operations). First, they permit low resistance to motion within the physiologic range, permitting minimal energy expenditure. However, in situations at or beyond this range, ligaments serve a protective role. Individual ligaments resist complex force and torque vectors through transferring uniaxial tensile loads from one bone to another. Theses tasks are performed by seven key subaxial spinal ligaments, which may be divided into intrasegmental systems (ligamentum flavum, facet capsules, and interspinous and intertransverse ligaments), which hold the functional spinal unit together, and the intersegmental system (anterior and posterior longitudinal ligaments and the supraspinous ligaments), which hold multiple vertebrae together. The anterior and posterior longitudinal ligaments consist of longitudinally oriented fibers running the length of several vertebrae as well connecting adjacent vertebral bodies. The ligamentum flavum extends from the anterior-inferior border of the laminae above to the posterior-superior border of the laminae below and is thickest toward midline. The ligamentum flavum contains the highest proportion of elastin and is always under tension (up to 15% in the neutral position), allowing contraction in extension without buckling; in full flexion, the ligament may stretch up to 35%. Capsular ligaments attach just beyond the margin of articular processes, with fibers running perpendicular to the plane of the facet joint. The posterior ligamentous complex and erector spinae musculature form the posterior tension band of the spinal column counterbalancing the compressive force on the anterior column. The posterior elements contribute significantly to the overall stiffness of the motion segment. The outer ligaments include the articular capsules, the anterior and posterior atlanto-occipital membranes, and the nuchal ligament. The inner ligaments include the paired alar ligaments, the apical ligament, the transverse atlantal ligament, the vertically Biomechanics of Spinal Instability Extrinsic variables that critically affect the pattern and severity of spinal column injury include impact magnitude, direction, point of force application, and rate of application.

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Complications of lateral plating in the minimally invasive lateral transpsoas approach treatment trichomonas order chloromycetin amex. Analysis of lumbar plexopathies and nerve injury after lateral retroperitoneal transpsoas approach: diagnostic standardization. Two-year clinical and radiographic success of minimally invasive lateral transpsoas approach for the treatment of degenerative lumbar conditions. Postoperative lumbar plexus injury after lumbar retroperitoneal transpsoas minimally invasive lateral interbody fusion. Case report: incisional hernia as a complication of extreme lateral interbody fusion. The posterior transpedicular approach for circumferential decompression and instrumented stabilization with titanium cage vertebrectomy reconstruction for spinal tumors: consecutive case series of 50 patients. Transpedicular partial corpectomy without anterior vertebral reconstruction in thoracic spinal metastases. Technique and clinical results of minimally invasive reconstruction and stabilization of the thoracic and thoracolumbar spine with expandable cages and ventrolateral plate fixation. Traumatic thoracolumbar spinal injury: an algorithm for minimally invasive surgical management. Minimally invasive spine surgery in the treatment of thoracolumbar and lumbar spine trauma. Minimally invasive corpectomy and posterior stabilization for lumbar burst fracture. Minimally invasive thoracic corpectomy: surgical strategies for malignancy, trauma, and complex spinal pathologies. Sagittal balance and spinopelvic parameters after lateral lumbar interbody fusion for degenerative scoliosis: a case-control study. Anterior lumbar interbody fusion in comparison with transforaminal lumbar interbody fusion: implications for the restoration of foraminal height, local disc angle, lumbar lordosis, and sagittal balance. A radiological comparison of anterior fusion rates in anterior lumbar interbody fusion. Enhancing the stability of anterior lumbar interbody fusion: a biomechanical com- 56. Biomechanical assessment of anterior lumbar interbody fusion with an anterior lumbosacral fixation screw-plate: comparison to stand-alone anterior lumbar interbody fusion and anterior lumbar interbody fusion with pedicle screws in an unstable human cadaver model. In vitro biomechanical comparison of an anterior and anterolateral lumbar plate with posterior fixation following single-level anterior lumbar interbody fusion. Anterior lumbar interbody fusion with stand-alone interbody cage in treatment of lumbar intervertebral foraminal stenosis: comparative study of two different types of cages. In 1911, Hibbs2 introduced the noninstrumented osseous fusion to stabilize the deformed spine. Fritz Lange,3 in the 1900s, internally splinted the spine using steel wires (later coated with tin) and fastened them to the spinous processes with a paraffin-sublimate silk. The great advancement in correcting spine deformity did not come until the latter half of the 20th century, when Harrington5 introduced spinal fixation with facet joint screws. He followed this advance with the development of the hook-rod system, which was supplemented with osseous fusion to correct idiopathic, neuromuscular, or acquired deformities. Long constructs were required, leading to occasional loosening of the instrumentation. In some cases, the use of distraction instrumentation in the thoracolumbar spine for correction of coronal plane deformities led to the loss of lumbar lordosis and flat-back syndrome4; fusions down to the sacrum and pseudarthrosis were also risk factors for flat-back syndrome. Challenges of the system included the need for long constructs and the increased incidence of neurological complications. Likewise, the use of translaminar facet joint screws was first described by Magerl13 in 1984. In the 1970s, Roy-Camille and associats14,15 described the use of posterior plates with sagitally positioned screws through the pedicles and articular processes. The straightforward approach for pedicle screws, as opposed to the anatomic approach, was a modification made by Roy-Camille but popularized by Suk and colleagues. Nonetheless, in the year 1977, Magerl17 published his "fixateur externe" for lower thoracic and lumbar spine, and after some years, Dick and colleagues18 introduced the "fixateur interne. Pedicle screws appeared superior to other posterior instrumentation being used at the time (hooks and sublaminar wires) in respect to their pullout strength and load-sharing capacity. They also provided threecolumn fixation, which could be used to distract, compress, and rotate the spine. The spine, as the osseous axis of the body, can be divided into four sections: cervical, thoracic, lumbar, and pelvic or sacrococcygeal. The thoracic vertebral body has similar sagittal and transverse diameters, and its posterior portion is excavated because of the spinal cord. On both sides of the vertebral body, proximal to the anterior border of the pedicle, lie two semicircular articular surfaces for the rib heads. The spinous processes, leaning caudally, are long and triangular though not as bifid as those in the cervical spine. The transverse processes start at the posterior part of the pedicle and follow obliquely both posteriorly and laterally. Anteriorly, each has a small articular surface for the tuberosity of the corresponding rib. They face posteriorly and laterally, whereas the inferior articular processes face frontally and medially. Study of the bony anatomy is crucial in the consideration of pedicle screw insertions, particularly the relationship between the transverse and articular processes and the pedicles in sawbones and cadavers. There are numerable variations in the dimensions and angulation of the thoracic pedicles. At T1 through T2, the angle is 15 to 20 degrees; at T3, 10 to 15 degrees; and at T4 through T12, 5 to 15 degrees. In the lower thoracic spine, the facets have a more sagittal orientation, providing more stability against rotation. The entry points of the thoracic pedicles are different in the upper, middle, and lower areas of the thoracic spine. From T1 to T3 and from T10 to T12 the pedicle entry point for screw fixation is roughly at the intersection of a horizontal line passing along the midline of the transverse process and a vertical line passing through the middle to lateral aspect of the facet. If the overlying inferior facet of the superior vertebra covers the superior articular process of the vertebra to be instrumented, the facet can be resected (except on the upper end of a construct to avoid destabilization). In the middle thoracic spine, from T4 to T9, the entry point for the pedicle is cranial to the transverse process. For the sagittal trajectory of the screws in the thoracic spine, a general tip is to drill perpendicular to the spinal curvature at the given level. In this technique, the screw placement is controlled with intraoperative fluoroscopy. The entry point in each vertebra is approximately at the level of the mammillary process: lateral to the level of the superior articular process at the intersection with the transverse process. The direction for the pedicle screws in the lumbar vertebrae in the transverse plane angles from lateral toward medial. The angular increase from L1 to L5 is 5 degrees at each progressive level, starting with 10 to 15 degrees at L1. For L1 to L5, the direction of a pedicle screw in the sagittal plane should be parallel to the superior end plate of the vertebra. The direction in the sagittal plane for S1 should be slightly ascending toward the superior end plate (Table 329-1) in order to try to capture the sacral promontory with the screw tip. Interarticular, inferior, and superior articular arteries are common sources of profuse bleeding and must be coagulated promptly. The anterior transverse artery, which travels under the transverse process with the exiting nerve root, should be preserved. Illustration showing some morphometric characteristics of the thoracic vertebrae from T1 to T12. The pedicle entry points (+) and their relationship to the transverse processes, laminae, and facets are shown in the center.

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Fine-cut coronal computed tomographic scan showing fracture of the sphenoid sinus wall medicine on airplane buy generic chloromycetin 250mg online, lying close to the position of the internal carotid artery, along with intracranial air and fluid in the sinus. Fine-cut coronal computed tomographic scan showing a tilted facture of the roof of the ethmoid with fluid tracking into the nasal cavity and the maxillary sinus. In addition, a blue light filter can be attached to the endoscope and light source that allows the visualization of even trace amounts of fluorescein. Although intrathecal fluorescein has been reported to be safe at these concentrations,56-61 there have been reports in the past of numbness and weakness of the lower extremities, opisthotonos, and seizures when higher concentrations were used. If no leak is present at the time of the investigation, the rate of detection is lower. Coronal images are obtained from the frontal sinuses to the dorsum sellae and, if indicated, the petrous bone. The site of the leak is indicated by bone dehiscence, appearance of contrast agent in the adjacent paranasal sinus, and distortion of the subarachnoid space; these findings are indicative of brain herniation. A variety of other organisms have been reported, and infections with multiple organisms, often including anaerobes, are common. Antibiotic Prophylaxis the value of antibiotic prophylaxis continues to be debated72; some reports have shown increased rates of infection with antibiotic treatment, and some have shown the opposite. Antibiotics may promote growth of resistant strains of organisms within the nasopharynx and consequently lead to infection with resistant or unusual organisms. At our institution, ceftriaxone or cefepime are used for perioperative prophylaxis. In patients with penicillin allergy, vancomycin or aztreonam are used for prophylaxis. Ampicillin-sulbactam or alternative antibiotics can be continued in the setting of dural inflammation. Although most fistulas heal spontaneously, the incidence of meningitis onset before a decision on surgical repair is about 11%. The most common organisms are Streptococcus pneumoniae and Haemophilus influenzae. Patients with a facial impact but without a vault fracture may be treated by reduction of the facial fractures and initial conservative treatment of the rhinorrhea. The patient should be placed on a bowel regimen that includes laxatives and stool softeners. If the leak does not cease within 3 days, intermittent or continuous drainage of lumbar fluid may be considered. Overdrainage can lead to intracranial aeroceles, severe brain displacement, and coma,83,84 and emergency drainage of the aerocele is necessary. It has been suggested but not proved that lumbar drainage may promote the entry of bacteria through the fistula, as well as impose its own risk for infection at the site of the spinal catheter; nonetheless, it is preferable to ventricular drainage. Anterior fossa surgery indicated for other reasons such as intracranial hematoma or to repair compound facial fractures, with accessible dural tears being treated at the same time 3. Radiologic appearances that indicate a low probability of natural dural repair: a. Anterior fossa fractures that are widely comminuted or separated and communicate with the nose or paranasal sinuses b. Fractures with soft tissue between the bony edges frontal lobes with light retraction. The standard flap is bicoronal, placed behind the hairline, and taken lateral to the level of the superior orbital margins. A fullthickness scalp flap is turned down and the periosteum is separated from the galea. Bur holes are placed laterally behind the temporal crest for cosmetic reasons after the temporalis muscle is detached. The inferior margin of the craniotomy is cut low across the frontal sinuses to avoid a midline inferior bur hole if possible. This must be done with care and in stages, depending on the size and extent of the frontal sinuses. If the site of the leak is known to be unilateral, an ipsilateral craniotomy is sufficient. The dura is opened horizontally on either side, with small flaps turned adjacent to the superior sagittal sinus. It is not usually necessary to divide the sinus, but if it is divided, it should be done so well forward to preserve all draining veins. Each frontal lobe is then carefully elevated; care must be taken to avoid excessive retraction pressure and to preserve at least one olfactory nerve. The crista galli varies considerably in size and shape, and the cribriform fossa may be quite deep. The first intradural sign may be an area of adherence of brain and arachnoid to the site of the fistula. Defects into the posterior planum sphenoidale and supradiaphragmatic pituitary fossa may need to be probed carefully to establish their full extent. If large, it should be filled with a bone graft, which may be taken from the inner calvaria. Primary suturing of a dural tear is rarely possible, and thus a graft of temporalis fascia or fascia lata is placed intradurally and held in place with nonabsorbable sutures and tissue glue. The intradural repair is made additionally secure by tamponade of the dural patch by the brain. The transected frontal sinus is stripped of mucosa, and the frontonasal duct is plugged with muscle and fat. A pericranial flap (or galeal flap if pericranium is not available) is turned over the frontal sinus and sutured to the dura. Frontal sinus mucosa is stripped from within the bone flap, and the craniotomy is reconstructed with titanium mini-plates. If no fistula is found after careful exploration, the operation should cease, and radiographs should be thoroughly reviewed for any other possible sites, such as the middle or posterior fossa. Avulsion of intact olfactory nerves and covering the entire anterior fossa floor with fascia are not recommended. If no other site is suggested by review and the leak is small, it may be treated indirectly with a lumboperitoneal shunt. The ideal treatment must be individualized for each patient, with considerations for the site and cause of leak and location of defect. The overall goals of repair involve identification of leak, preparation for repair of leak, performing the repair, and promotion of healing. Although rigid skull base reconstruction may appear necessary, especially with large skull base defects, this is often not the case. Multiple graft layers can be advantageous because failure of one layer can be salvaged with a subsequent layer. These grafts can be placed in a variety of layers, including the subdural plane (also known as inlay or underlay techniques), intracranially, extradurally, or intranasally (also referred to as onlay and overlay techniques). The advantages of autologous tissue such as fascia lata, abdominal fat, or turbinate mucosa include innate growth factors and rapid healing with limited risk of foreign body reaction. Risks exist, however, and include donor site morbidity and longer operative time necessary to harvest graft tissue. At our institution, if an early leak recurs, a period of lumbar drainage may be undertaken. The dura is explored extradurally, and the tear is repaired in a watertight manner. The posterior wall of the sinus is excised, the sinus mucosa is stripped, and the frontal nasal duct is plugged with fat or muscle. Longitudinal petrous fractures may disrupt the roof of the middle ear but rarely necessitate repair. PatientPositioningandExposure the patient is placed supine or in the full lateral position to bring the head fully lateral. A small lateral craniotomy is performed, and the inferior margin is drilled to the floor of the middle fossa. The rate of successful leak closure has been cited to be approximately 90% with the first endoscopic attempt and as high as 98% with the second attempt; complication rates are as low as 0. Regardless of the specific approach, topical nasal decongestants and lidocaine with epinephrine injection have been accepted as standard perioperative preparation to improve surgical visualization, as well as provide for hemostasis during endoscopy. The site of the fistula is sought over the region of the tegmen tympani, and an intradural repair is performed, as described earlier.

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Biomechanical study on the effect of cervical spine fusion on adjacent-level intradiscal pressure and segmental motion symptoms internal bleeding buy generic chloromycetin 500mg on line. Kyphotic malalignment after anterior cervical fusion is one of the factors promoting the degenerative process in adjacent intervertebral levels. Comparison of cervical spine kinematics using a fluoroscopic model for adjacent segment degeneration. Invited submission from the Joint Section on Disorders of the Spine and Peripheral Nerves, March 2007. Effect of lower two-level anterior cervical fusion on the superior adjacent level. Adjacent segment degeneration following spinal fusion for degenerative disc disease. Stabilizing potential of anterior, posterior, and circumferential fixation for multilevel cervical arthrodesis: an in vitro human cadaveric study of the operative and adjacent segment kinematics. Adjacent segment hypermobility after lumbar spine fusion: no association with progressive degeneration of the segment 5 years after surgery. Adjacent segment disease in the lumbar spine following different treatment interventions. Long-term results after anterior cervical discectomy and fusion with allograft and plating: a 5- to 11-year radiologic and clinical follow-up study. Minimum 10-year follow-up study of anterior lumbar interbody fusion for isthmic spondylolisthesis. Adjacent segment disease after posterior lumbar interbody fusion: based on cases with a minimum of 10 years of follow-up. L5-S1 segment survivorship and clinical outcome analysis after L4-L5 isolated fusion. Four-year follow-up results of lumbar spine arthrodesis using the Bagby and Kuslich lumbar fusion cage. Risk factors for adjacent-segment failure following lumbar fixation with rigid instrumentation for degenerative instability. Lumbar motion segment pathology adjacent to thoracolumbar, lumbar, and lumbosacral fusions. Kinematic evaluation of the adjacent segments after lumbar instrumented surgery: a comparison between rigid fusion and dynamic non-fusion stabilization. Adjacent segment degeneration after lumbar interbody fusion with percutaneous pedicle screw fixation for adult low-grade isthmic spondylolisthesis: minimum 3 years of follow-up. Two-level anterior lumbar interbody fusion with percutaneous pedicle screw fixation: a minimum 3-year follow-up study. Total disc arthroplasty does not affect the incidence of adjacent segment degeneration in cervical spine: results of 93 patients in three prospective randomized clinical trials. Post-laminectomy kyphosis in patients with cervical ossification of the posterior longitudinal ligament: does it cause neurological deterioration Spinal deformity and instability after multilevel cervical laminectomy for spondylotic myelopathy. Laminoplasty versus laminectomy and fusion for multilevel cervical myelopathy: an independent matched cohort analysis. Analysis and prevention of spinal column deformity following cervical laminectomy. Pathogenesis and prophylaxis of postlaminectomy deformity of the spine after multiple level laminectomy: difference between children and adults. A comparison of anterior cervical fusion, cervical laminectomy, and cervical laminoplasty for the surgical management of multiple level spondylotic radiculopathy. Factors associated with cervical instability requiring fusion after cervical laminectomy for intradural tumor resection. Spinal column deformity and instability after lumbar or thoracolumbar laminectomy for intraspinal tumors in children and young adults. Analysis of cervical instability resulting from laminectomies for removal of spinal cord tumor. Incidence of spinal column deformity after multilevel laminectomy in children and adults. Long-term outcome of laminectomy for cervical ossification of the posterior longitudinal ligament. Cervical alignment and range of motion after laminoplasty: radiographical data from more than 500 cases with cervical spondylotic myelopathy and a review of the literature. Techniques for the ventral correction of postsurgical cervical kyphotic deformity. Deformity planning for sagittal plane corrective osteotomies of the spine in ankylosing spondylitis. Anterior cervical corpectomy in patients previously managed with a laminectomy: short-term complications. Results of surgical treatment for degenerative cervical myelopathy: anterior cervical corpectomy and stabilization. Biomechanical comparison of cervical spine reconstructive techniques after a multilevel corpectomy of the cervical spine. Anterior cervical fixation: analysis of load-sharing and stability with use of static and dynamic plates. An outcomes analysis of the treatment of cervical pseudarthrosis with posterior fusion. The efficacy of anterior cervical plating in the management of symptomatic pseudoarthrosis of the cervical spine. Treatment of anterior cervical pseudoarthrosis: posterior fusion versus anterior revision. A meta-analysis of the clinical and fusion results following treatment of symptomatic cervical pseudarthrosis. Risk factors for dysphagia after anterior cervical spine surgery: a two-year prospective cohort study. Preoperative laryngeal nerve screening for revision anterior cervical spine procedures. Translaminar versus pedicle screw fixation of C2: comparison of surgical morbidity and accuracy of 313 consecutive screws. Seven years of experience with C2 translaminar screw fixation: clinical series and review of the literature. Biomechanical comparison of transpedicular versus intralaminar C2 fixation in C2-C6 subaxial constructs. Prospective study of surgical treatment of degenerative spondylolisthesis: comparison between decompression alone and decompression with Graf system stabilization. Minimum 10-year outcome of decompressive laminectomy for degenerative lumbar spinal stenosis. Clinical outcomes and radiological instability following decompressive lumbar laminectomy for degenerative spinal stenosis: a comparison of patients undergoing concomitant arthrodesis versus decompression alone. A radiographic assessment of the ability of the extreme lateral interbody fusion procedure to indirectly decompress the neural elements. Indirect foraminal decompression is independent of metabolically active facet arthropathy in extreme lateral interbody fusion. Unilateral versus bilateral percutaneous pedicle screw fixation in minimally invasive transforaminal lumbar interbody fusion. Dorsal lumbar interbody fusion for chronic axial, mechanical low back pain: a modification of two established techniques. Clinical outcomes after lumbar discectomy for sciatica: the effects of fragment type and anular competence. Long-term outcomes of standard discectomy for lumbar disc herniation: a follow-up study of more than 10 years. Results and risk factors for recurrence following single-level tubular lumbar microdiscectomy. A 10-year follow-up study on long-term clinical outcomes of lumbar microendoscopic discectomy. Long-term results of disc excision for recurrent lumbar disc herniation with or without posterolateral fusion. Posterior lumbar interbody fusion for revision disc surgery: review of 50 cases in which carbon fiber cages were implanted.

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In their surgical correction medicine hat buy discount chloromycetin 500 mg on-line, anterior discectomies help to shorten the anterior column, which may help to re-create the normal thoracic kyphosis or to open up the anterior column to reduce an excessive or pathologic kyphosis. When combined with the SouthwickRobinson approach, it can provide exposure from C3 down to T4. The patient is positioned with the neck extended by placing a towel roll under the scapulae, with the shoulders pulled back. The incision extends from the manubrial notch to 3 cm caudal to the sternal angle, which can be extended proximally anterior to the sternocleidomastoid if more proximal levels are required. A 2-cm wide skin flap is raised from the manubriosternum bilaterally, and with blunt dissection with the finger, the posterior manubrial surface is freed. The internal thoracic artery should be ligated around the second intercostal space, which is where the transverse limb of the osteotomy should exit. A unilateral transverse cut, or bilateral cut, can be made with an oscillating saw to achieve the width of the exposure. A retractor can be placed vertically to maintain exposure to the anterior mediastinum, and finger dissection can be used to mobilize the retrosternal soft tissue. In this U-shaped pocket, the common carotid artery is on the left, and the brachiocephalic artery and vein are on the right. The floor is formed by the trachea and esophagus and can be retracted left to expose the spine. It loops under the right subclavian artery, a branch of the brachiocephalic trunk, and ascends near the trough formed by the trachea and esophagus on the right. For exposure down to T5, it may be necessary to dissect along the lateral border of the ascending aorta until the upper border of the heart. The left brachiocephalic vein may have to be retracted distally and (rarely) even ligated for adequate exposure. Tumor Thoracic spinal neoplasms may present with pain, neurological deficit, or pathologic fracture, or as an incidental finding. Several objective scoring systems are available to determine whether surgical intervention is appropriate, including the Tomita28 and revised Tokuhashi29 scores. Surgical intervention can be either an attempted curative resection or palliative decompression with stabilization. There is evidence to suggest that direct decompressive surgery with adjuvant radiotherapy leads to a better outcome than radiotherapy alone in metastatic spinal cord compression. Hence, epidural spinal cord compression is usually the result of tumor extension from the vertebral body dorsally into the spinal canal. For primary tumors of the thoracic spine, a combined anterior and posterior approach, or an all-posterior approach for an en bloc excision, is possible. For metastatic diseases, the treatment may depend on the prognosis and condition of the patient because the limited life expectancy may not justify open anterior surgery. Open Thoracotomy for T2 to T8 the transthoracic approach is the utilitarian approach to the anterior vertebral column of the thoracic spine. Preoperative pulmonary assessment is required to assess for single lung ventilation and the likelihood of postoperative pulmonary complications. The patient is positioned in the lateral decubitus position and stabilized with a kidney rest or sandbags. The upper thoracic spine (T2 to T9) is best approached from the right side to avoid the heart and aortic arch. The thoracolumbar spine (T10 to L2) can be approached from the left to avoid liver retraction. The choice should also be based on the location of pathology, such as a rightsided paracentral disk herniation should be approached from the right, whereas a scoliosis correction should be approached from the convex side. The latissimus dorsi is divided in the direction of the incision, followed by the serratus anterior along the same line to the ribs. The chest can be entered either by resecting one or more ribs or through an intercostal space. Rib resection creates a better exposure, and the cut ribs can be used for bone grafting. The deep rib bed periosteal layer is incised, and retropleural dissection can be performed by blunt finger dissection and wet sponge stick to elevate and separate the parietal pleura from the periosteal layer. The ribs are slowly spread apart using a rib spreader to allow the muscles to adapt. The anesthetist deflates the lung, which can then be retracted anteriorly by a lung retractor and packed with moist pads. In the posterior mediastinum, the pleura is incised over the lateral side of the esophagus, the esophagus and azygos vein are mobilized with blunt finger dissection, and the venous tributaries are tied off. The incision site is marked in the posterior axillary line directly over the correct intercostal space, using fluoroscopic guidance. A thoracoscope with a 30-degree lens is placed through the initial incision, and the thorax is inspected. Retracting and camera ports are usually added two to three interspaces from the operating port. They are near the posterior axillary line but may be more anterior on the chest wall. After the other ports are inserted, the camera is moved, and the original port becomes the operating access. In the upper thorax, both retractor and camera ports are caudal to the operating port. In the middle thorax, there can be more variation because more space is available in the midchest. In the lower thorax, unless well retracted, the diaphragm obscures the operating field. The middle column consists of the posterior vertebral body, posterior anulus fibrosus, and posterior longitudinal ligament. The posterior column is composed of the posterior osseous arch, including the facets, and the posterior ligamentous complex. Disruption of the middle column is the most important determinant in mechanical stability, as validated by biomechanical studies. Before bone union occurs, the construct may need to be fixed and stabilized with instrumentation. Internal fixation of the spine allows earlier mobilization and provides a stable mechanical environment for bone healing. In general, dual-rod designs have greater adjustability and increased load sharing47 but are less rigid, whereas plates are stiffer and less easily fatigued. Although the biomechanical characteristics of these two systems are different, the bending stiffness and load-sharing characteristics are very similar, such that their choice in clinical practice should be based on ease of use and surgeon familiarity rather than the material properties of the implants. In a cadaveric human model after an L1 corpectomy, the spines were fixed with anterior instrumentation with monoaxial screws and rods, with short-segment (one level above and below) and long segment (two levels above and below) pedicle screw fixation. They underwent biomechanical testing for 6 degrees of freedom and found that a long-segment posterior construct was the most rigid system. Split Diaphragm Approach for Thoracolumbar Junction A curvilinear incision is made from the lateral thorax along one of the fixed ribs, normally one level cephalad to the target vertebra, toward the rectus abdominis and stopping at its lateral border. In the lower part of the incision, part of the diaphragm needs to be resected to enhance exposure (Case Study 327-1 and Videos 327-1 through 327-9). At least a 1-cm diaphragmatic margin along the chest wall is preserved to allow reattachment during closure. In the abdominal cavity, the external oblique is divided along the line of its fibers, then the internal oblique perpendicular and transverse abdominis are divided to expose the retroperitoneal space. A plane is developed between the retroperitoneal fat and fascia that overlie the psoas muscle. The psoas muscle is moblized medially to reach the anterolateral surface of the vertebral bodies. Thoracoscopic Approach There has been increased interest in minimally invasive exposure of the anterior spine. Thoracoscopic approaches can be technically demanding with a long learning curve, and a detailed description is beyond the scope of this chapter.

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In a separate study medicine pill identification order chloromycetin canada,58 the initial stiffness of pedicle screws versus lateral mass screws was not significant. However, after cyclic loading (fatigue testing), there was significantly higher stiffness in pedicle screw constructs than in lateral mass screw constructs in flexionextension and lateral bending, but not in axial rotation. Transpedicular screws also have increased stiffness in comparison with lateral mass screws when spanning two unstable cervical levels rather than one. The immediate stability afforded by contemporary constructs facilitates patient mobility postoperatively. In addition, improved techniques enable the treatment of increasingly complex spinal disease. The ability of interspinous wiring and Halifax clamp constructs to exhibit stiffness in extension can be explained by the compressive preloading of the posterior element allowed by the construct, which increases friction between the facet joints and limitation of motion in extension. Gill and associates performed no fatigue testing of any of the constructs; therefore, the results may have less relevance to clinical settings in which fatigue of the surgical construct is a factor. Weis and coworkers9 studied posterior plating with lateral mass screws and the Rogers interspinous wiring technique in fatigue testing of biomechanical models based on cadaveric cervical calf spines, a model previously validated by Coe and associates57 and by Sutterlin and colleagues. Weis and coworkers found significantly greater stiffness in axial rotation when posterior plating was used, rather than interspinous wiring, immediately after instrumentation, but they found no statistical difference in axial range of motion or stiffness with fatigue testing. They also found no difference in flexion-extension range of motion between posterior plating and interspinous wiring immediately after instrumentation or with fatigue testing. On fatigue testing, however, there was increased stiffness in flexion and extension with posterior plating. Transpedicular screw fixation for traumatic lesions of the middle and lower cervical spine: description of the techniques and preliminary report. Anatomic comparison of the Roy-Camille and Magerl techniques for screw placement in the lower cervical spine. Biomechanical study of screws in the lateral masses: variables affecting pull-out resistance. Biomechanical analysis of transpedicular screw fixation in the subaxial cervical spine. A comparison of pedicle and lateral mass screw construct stiffnesses at the cervicothoracic junction: a biomechanical study. An operation for progressive spinal deformities: a preliminary report of three cases from the service of the orthopaedic hospital. In vitro biomechanical comparison of multistrand cables with conventional cervical stabilization. A biomechanical comparison of three surgical approaches in bilateral subaxial cervical facet dislocation. The triple wire fixation technique for stabilization of acute fracture-dislocations: a biomechanical analysis. Indications and technics for early stabilization of the neck in some fracture dislocations of the cervical spine. Bilateral facet to spinous process fusion: a new technique for posterior spinal fusion after trauma. A biomechanical evaluation of cervical spinal stabilization methods in a bovine model. Cervical spondylotic myelopathy: treatment with posterior decompression and Luque rectangle bone fusion. Posterior stabilization of cervical spine fractures and subluxations using plates and screws. Posterior cervical lateral mass screw fixation: analysis of 1026 consecutive screws in 143 patients. Posterior internal fixation with screw plates in traumatic lesions of the cervical spine. Posterior cervical fixation using a new polyaxial screw and rod system: technique and surgical results. Safety evaluation of freehand lateral mass screw fixation in the subaxial cervical spine: evaluation of 1256 screws. Pullout strength comparison of two methods of orienting screw insertion in the lateral masses of the bovine cervical spine. Anatomic and biomechanical study of posterior cervical spine plate arthrodesis: an evaluation of two different techniques of screw placement. Lateral mass screw fixation in the cervical spine: a systematic literature review. The medial cortical pedicle screw-a new technique for cervical pedicle screw placement with partial drilling of medial cortex. Transpedicular screwing of the seventh cervical vertebra: anatomical considerations and surgical technique. Surgical anatomy of the cervical pedicles: landmarks for posterior cervical pedicle entrance localization. Complications of pedicle screw fixation in reconstructive surgery of the cervical spine. A finite element modeling of posterior atlantoaxial fixation and biomechanical analysis of C2 intralaminar screw fixation. Biomechanical comparison of two-level cervical locking posterior screw/rod and hook/rod techniques. Biomechanical analysis of a novel hook-screw technique for C1-2 stabilization: technical note. The C7-T1 junction: problems with diagnosis, visualization, instability, and decompression. Posterior cervicothoracic instrumentation: testing the clinical efficacy of tapered rods (dual diameter rods). Complications and survival after long posterior instrumentation of cervical and cervicothoracic fractures related to ankylosing spondylitis or diffuse idiopathic skeletal hyperostosis. Biomechanical evaluation of cervical spinal stabilization methods in a human cadaveric model. Cheung Anterior approaches to the thoracic spine can be used alone or combined in a staged or sequential procedure with a posterior approach. The anterior approach offers several distinct advantages: it allows direct visualization of the vertebral body, anterior releases, discectomies, fewer levels of fixation, and less tissue trauma than posterior muscle dissection. The anterior approach can be used in the treatment of severe rigid scoliosis or kyphosis, spinal infections, tumors, trauma, or degenerative conditions. The aims of this chapter are to allow the reader to appreciate the historical development in anterior spinal surgery, to understand the indications for the anterior approach in the thoracic spine, and to describe in detail the common approaches to the anterior thoracic spine and the implants used. With improved surgical techniques, minimally invasive approaches such as thoracoscopic surgeries became widely accepted to provide adequate exposure to the anterior thoracic spine with reduced wound-related morbidities. The scope of thoracoscopy has evolved from its initial use in tuberculosis-related effusions, to thoracic disk herniations, tumors, and fractures. It leads to a reduction in pulmonary morbidity, chest pain, and shoulder girdle dysfunction; causes less tissue trauma; allows earlier postoperative mobilization, leading to a shorter hospital stay; and produces better cosmetic results. For instance, early descriptions of total en bloc spondylectomy for radical excision of thoracic spinal tumors involved staged or combined anterior and posterior approaches. The development of instrumentation allows more complex reconstruction and deformity correction of the thoracic spine. However, spine surgeons should appreciate the underlying principles when an anterior approach is preferred. These include (1) an anterior pathology compressing the dura and spinal cord allowing direct decompression; (2) an anterior lesion requiring excision; (3) loss or destruction of the anterior vertebral column needing reconstruction; (4) a rigid spinal deformity whereby anterior discectomies and releases can modify the flexibility; and (5) correction of local sagittal deformity or imbalance in the thoracic region with shortening or release of the anterior column. Hodgson and Stock reported the most extensive series on their experience in Hong Kong regarding this subject. This was followed by anterior strut graft fusion using autogenous rib, iliac, or fibula grafts. The 5-, 10- and 15-year reports indicated that all three groups achieved favorable outcomes.

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Cerebral steal during hypercapnia and the inverse reaction during hypocapnia observed by the 133 xenon technique in man 98941 treatment code purchase 500mg chloromycetin with mastercard. Does acute hyperventilation provoke cerebral oligaemia in comatose patients after acute head injury Relationship between arterial carbon dioxide and end-tidal carbon dioxide in mechanically ventilated adults with severe head trauma. Effects of hypoxia and normocarbia on cerebral blood flow and metabolism in conscious man. The influence of acute normovolemic anemia on cerebral blood flow and oxygen consumption of anesthetized rats. Influence of carbon monoxide and of hemodilution on cerebral blood flow and blood gases in man. Reduced cerebral blood flow, oxygen delivery, and electroencephalographic activity after traumatic brain injury and mild hemorrhage in cats. Marked protection by moderate hypothermia after experimental traumatic brain injury. Post-traumatic brain hypothermia reduces histopathological damage following concussive brain injury in the rat. Behavioral protection by moderate hypothermia initiated after experimental traumatic brain injury. Intracerebral temperature in neurosurgical patients: intracerebral temperature gradients and relationships to consciousness level. Lund Therapy-pathophysiology-based therapy or contrived over-interpretation of limited data Cerebral and cardiovascular responses to changes in head elevation in patients with intracranial hypertension. Effect of head elevation on intracranial pressure, cerebral perfusion pressure, and cerebral blood flow in head-injured patients. Influence of body position on tissue-pO2, cerebral perfusion pressure and intracranial pressure in patients with acute brain injury. Treatment of increasing intracranial pressure secondary to the acute abdominal compartment syndrome in a patient with combined abdominal and head trauma. Effects of increased intra-abdominal pressure upon intracranial and cerebral perfusion pressure before and after volume expansion. Sufentanil, fentanyl, and alfentanil in head trauma patients: a study on cerebral hemodynamics. Total intravenous anesthesia including ketamine versus volatile gas anesthesia for combat-related operative traumatic brain injury. Ketamine for analgosedative therapy in intensive care treatment of head-injured patients. Ketamine as a neuroprotective and anti-inflammatory agent in children undergoing surgery on cardiopulmonary bypass: a pilot randomized, doubleblind, placebo-controlled trial. Inhibitory effects of ketamine on lipopolysaccharide-induced microglial activation. The influence of systemic arterial pressure and intracranial pressure on the development of cerebral vasogenic edema. Extracranial insults and outcome in patients with acute head injury-relationship to the Glasgow Coma Scale. Combined effect of respirator-induced ventilation and superoxide dismutase in experimental brain injury. Reversal of incipient brain death from head-injury apnea at the scene of accidents. Delayed posttraumatic brain hyperthermia worsens outcome after fluid percussion brain injury: a light and electron microscopic study in rats. Failure of prophylactically administered phenytoin to prevent early posttraumatic seizures. Levetiracetam versus phenytoin for seizure prophylaxis in severe traumatic brain injury. The ability of paramedics to predict aspiration in patients undergoing prehospital rapid sequence intubation. Antibiotic prophylaxis of early onset pneumonia in critically ill comatose patients. Protective effect of intravenously administered cefuroxime against nosocomial pneumonia in patients with structural coma. Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia. Thromboembolism after trauma: an analysis of 1602 episodes from the American College of Surgeons National Trauma Data Bank. Efficacy of deep venous thrombosis prophylaxis in trauma patients and identification of high-risk groups. Venous thromboembolism in the patient with acute traumatic brain injury: screening, diagnosis, prophylaxis, and treatment issues. Utility of once-daily dose of low-molecular-weight heparin to prevent venous thromboembolism in multisystem trauma patients. Prospective double-blind placebocontrolled randomized trial on the use of ranitidine in preventing postoperative gastroduodenal complications in high-risk neurosurgical patients. Sucralfate versus antacids or H2-antagonists for stress ulcer prophylaxis: a meta-analysis on efficacy and pneumonia rate. Prevention of yeast translocation across the gut by a single enteral feeding after burn injury. Early enteral nutrition after brain injury by percutaneous endoscopic gastrojejunostomy. Percutaneous endoscopic gastrostomy reduces total hospital costs in head-injured patients. Cerebral salt wasting after traumatic brain injury: an important critical care treatment issue. Hyperglycemia increases brain injury caused by secondary ischemia after cortical impact injury in rats. Hyperglycemia increases neurological damage and behavioral deficits from post-traumatic secondary ischemic insults. Strict glycaemic control in patients hospitalised in a mixed medical and surgical intensive care unit: a randomised clinical trial. Pituitary imaging abnormalities in patients with and without hypopituitarism after traumatic brain injury. Prevalence of anterior pituitary insufficiency 3 and 12 months after traumatic brain injury. Acute secondary adrenal insufficiency after traumatic brain injury: a prospective study. Effect of barbiturate coma on adrenal response in patients with traumatic brain injury. Consensus guidelines on screening for hypopituitarism following traumatic brain injury. Hypothalamopituitary dysfunction following traumatic brain injury and aneurysmal subarachnoid hemorrhage: a systematic review. Expert meeting: hypopituitarism after traumatic brain injury and subarachnoid haemorrhage. Clinical and pathophysiological significance of severe neurotrauma in polytraumatized patients. The effect of a femoral fracture on concomitant closed head injury in patients with multiple injuries. Assessment of the relationship between timing of fixation of the fracture and secondary brain injury in patients with multiple trauma. Effects of cisatracurium on cerebral and cardiovascular hemodynamics in patients with severe brain injury. Hyperosmolar therapy in the treatment of severe head injury in children: mannitol and hypertonic saline.

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Functional outcome and mortality showed a slight but not statistically significant improvement medications descriptions 500mg chloromycetin amex. In addition, secondary ischemic insults can be anticipated and prevented or detected early and treated before they become sufficiently severe as to injure the brain. These thresholds for severity of intracranial hypertension assume a normal blood pressure. There are no studies that clearly establish one of these as the most appropriate threshold for treatment. A detailed discussion of this topic as it relates specifically to critical care management is also available in the expanded version of this chapter at ExpertConsult. Monitoring for Secondary Injury Processes: Cerebral Ischemia As with intracranial hypertension, there are no reliable clinical findings for cerebral ischemia. The neurological signs caused by brain injury usually obscure any focal findings that might be caused by secondary ischemia. Monitoring for Secondary Ischemic Insults Secondary ischemic insults are global and usually transient. In addition, physiologic variables that are the common causes of secondary ischemic insults should be monitored. Stocchetti and coworkers117 compared simultaneous measurements of SjvO2 in the right and left jugular bulbs of 32 patients with severe head injury. Fifteen patients had a maximal right-to-left difference in SjvO2 greater than 15%; three additional patients had differences greater than 10%. Metz and associates116 compared bilateral SjvO2 measurements in 22 patients with severe head injury. They found that the greatest success in identifying transient ischemic episodes was observed if the following strategy was used: when the injury is diffuse, the catheter should be placed on the side of dominant flow; when the injury is focal, the catheter should be placed on the side of the lesion. These studies are clear that, when there are focal lesions, there may be significant differences in the oxygen saturation measured in the left and right jugular bulbs. If the monitoring strategy is to use SjvO2 as a monitor of global oxygenation, then cannulating the dominant jugular vein is the most logical choice because it will be the most representative of the whole brain. However, if the strategy is to identify the most abnormal oxygen saturation, then the recommendations of Metz and associates116 should be followed. Gibbs and colleagues118 studied 50 normal young males and observed that their SjvO2 ranged from 55% to 71% (mean of 61. These values for SjvO2 are lower than normal mixed venous oxygen saturation, indicating that the brain normally extracts oxygen more completely from arterial blood than do many other organs. In head-injured patients, the average SjvO2 is higher than normal and the range for SjvO2 is considerably wider than it is in normal subjects. In a series of 116 patients with continuous measurement of SjvO2 for the first 5 to 10 days after a severe head injury; SjvO2 averaged 68. Carotid puncture is the most common complication associated with internal jugular vein catheterization. However, it rarely has serious consequences, and the risk can be minimized by making certain that the puncture is lateral to the carotid pulsation. The vast majority of arterial punctures can be managed conservatively by applying local pressure for 10 minutes. Line sepsis is a complication that is commonly associated with all types of indwelling catheters. Most studies have reported an overall rate of 0 to 5 episodes of infection per 100 catheters. However, more recently available catheters have been found to have much improved performance. Mortality was higher in patients with one episode or multiple episodes (37% and 69%), as opposed to no episodes of desaturation (21%). In 1999, Cormio and colleagues115 reported on a series of 450 patients who underwent jugular venous saturation monitoring, noting that high SjvO2 (>75%) occurs with hyperemia or after infarction, as nonviable tissue does not extract oxygen. In addition, these patients were found to have worse outcome at 6 months postinjury, compared with patients with mean SjvO2 of 56% to 74%. Early studies suggested that either jugular bulb would provide similar SjvO2 information in most normal people. However, the 4-French or 5-French catheter used for SjvO2 monitoring is quite small relative to the lumen of the internal jugular vein. Coplin and colleagues126 reported that 8 of 20 patients investigated with ultrasonography following jugular bulb catheterization had nonobstructive, subclinical thrombi. Symptomatic thrombosis of the internal jugular vein is very uncommon with jugular bulb catheters but could have serious consequences. CerebralMicrodialysis Intracerebral microdialysis is a brain monitoring modality recently introduced for neurocritical care of brain injury patients. Microdialysis is a valuable technique that allows for measurement of endogenous and exogenous molecules of various sizes in repetitive intervals without tissue sampling. This technique can be utilized in vitro and in vivo and is capable of providing large amounts of information in both research and clinical settings with the advantage of continuous sampling without tissue destruction. The principal biochemical markers measured using microdialysis include markers of cerebral metabolism, ischemia, or energyrelated metabolism; neurotransmitters or markers of excitotoxic states; and markers of tissue damage and inflammation. The availability of modern analytic techniques has made microdialysis a "universal" biosensor capable of monitoring essentially every small and medium-sized molecular compound in the interstitial fluid. Chemical substances from the interstitial fluid diffuse across the membrane into the perfusion fluid inside the catheter. The recovery of a particular substance is defined as the concentration in the dialysate expressed as a percentage of the concentration in the interstitial fluid. Valadka and associates128 found that the likelihood of death following a severe head injury increased with increasing duration of time with PbtO2 less than 15 mm Hg, and with any occurrence of a PbtO2 less than 6 mm Hg. Intracranial hypertension was the most common cause of jugular venous desaturation in a prospective study of 116 patients with severe head injury, accounting for 44% of the total number of episodes. Increases in extracellular glutamate have also been reported during posttraumatic seizures. Although promising, the clinical utility is limited to postcraniotomy patients, which may limit its widespread use. Miller and Becker149 found in a group of 225 patients that the presence of a systolic blood pressure less than 95 mm Hg on arrival in the emergency room was associated with a twofold increase in the mortality rate. Hypotension is also common during hospitalization and is associated with a worse outcome. In a prospective study in which SjvO2 was monitored in 116 patients, hypotension was the third most common cause of jugular venous desaturation, accounting for 10% of the episodes. Pietropaoli and colleagues152 observed in a study of 53 patients with early surgery for traumatic intracranial hematomas that intraoperative hypotension (systolic blood pressure <90 mm Hg) was associated with a mortality rate of 82% compared to 25% in patients without hypotension. For these reasons, blood pressure is a particularly important physiologic parameter to monitor after severe head injury. Central venous access is often required to administer vasopressors or hyperosmotic agents (Video 349-1). Whether or not hyperventilation can actually result in cerebral ischemia in head-injured patients is controversial. However, several studies suggest that excessive hyperventilation after severe head injury can be a secondary ischemic insult. In a prospective study in which SjvO2 was monitored in 116 patients with severe head injury,71 hypocapnia was the second most common cause of jugular venous desaturation, accounting for 36% of the episodes. Lewelt and colleagues147 showed in a fluid percussion injury model that autoregulation was severely impaired after both low-level and high-level injuries. Five of the patients had ischemic areas that demonstrated the inverse steal response. In a fluid percussion head injury model in cats, a 1- to 2-atmosphere impact resulted in a mild impairment of the cerebral vasodilator response to hypoxia. It is likely that this is one of the mechanisms whereby hypoxia increases the severity of traumatic injuries. Pulmonary complications that can result in hypoxia are common after severe head injury. Hypoxia that persists after the initial resuscitation or develops within the first 24 to 48 hours after injury can be due to a lung contusion, atelectasis, fat embolus, pneumonia, or adult respiratory distress syndrome. In a prospective study in which SjvO2 was monitored in 116 patients,71 hypoxia was the fourth most common cause of jugular desaturation, accounting for 8% of the episodes. In a study of 225 patients, hypoxia, which was present in 35%, increased the mortality rate from 24% to 50%.

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S-100 is also present in extracranial tissues treatment 4s syndrome buy on line chloromycetin, including chondrocytes and adipocytes. S-100 levels are also increased within the first 12 to 24 hours after hemorrhagic shock, as well as during cardiopulmonary bypass, both irrespective of neurological injury. Despite this, none have yet demonstrate the diagnostic and prognostic capabilities necessary to warrant routine clinical application. This process will help narrow the field of potential biomarkers so that the most specific and easily measured candidates can be chosen for clinical validation and assay development. Blood-based biomarkers for traumatic brain injury: evaluation of research approaches, available methods and potential utility from the clinician and clinical laboratory perspectives. Update on protein biomarkers in traumatic brain injury with emphasis on clinical use in adults and pediatrics. Neuron-specific enolase, S100B, and glial fibrillary acidic protein levels as outcome predictors in patients with severe traumatic brain injury. Biochemical serum markers for brain damage: a short review with emphasis on clinical utility in mild head injury. Spectrin breakdown products in the cerebrospinal fluid in severe head injury-preliminary observations. Evidence for an interaction between ubiquitin-conjugating enzymes and the 26S proteasome. Ubiquitin C-terminal hydrolase is a novel biomarker in humans for severe traumatic brain injury. Serum levels of ubiquitin C-terminal hydrolase distinguish mild traumatic brain injury from trauma controls and are elevated in mild and moderate traumatic brain injury patients with intracranial lesions and neurosurgical intervention. Serum neuron-specific enolase, S100B, and myelin basic protein concentrations after inflicted and noninflicted traumatic brain injury in children. Serum biomarker concentrations and outcome after pediatric traumatic brain injury. Biomarkers for the clinical differential diagnosis in traumatic brain injury-a systematic review. Immunohistochemistry and serum values of S-100B, glial fibrillary acidic protein, and hyperphosphorylated neurofilaments in brain injuries. Role of phosphorylated neurofilament H as a diagnostic and prognostic marker in traumatic brain injury. C-tau biomarker of neuronal damage in severe brain injured patients: association with elevated intracranial pressure and clinical outcome. Serum cleaved tau protein levels and clinical outcome in adult patients with closed head injury. Amyloid beta 1-42 and tau in cerebrospinal fluid after severe traumatic brain injury. Alterations in cerebrospinal fluid apolipoprotein E and amyloid beta-protein after traumatic brain injury. Traumatic brain injury increases beta-amyloid peptide 1-42 in cerebrospinal fluid. Amyloid-beta dynamics correlate with neurological status in the injured human brain. Monitoring of brain interstitial total tau and beta amyloid proteins by microdialysis in patients with traumatic brain injury. Glial fibrillary acidic protein in serum after traumatic brain injury and multiple trauma. Predictive value of S-100beta protein for prognosis in patients with moderate and severe traumatic brain injury: systematic review and meta-analysis. Validation of serum markers for blood-brain barrier disruption in traumatic brain injury. Elevated levels of serum glial fibrillary acidic protein breakdown products in mild and moderate traumatic brain injury are associated with intracranial lesions and neurosurgical intervention. Neuronal and glial markers are differently associated with computed tomography findings and outcome in patients with severe traumatic brain injury: a case control study. Biomarkers for the diagnosis, prognosis, and evaluation of treatment efficacy for traumatic brain injury. Interleukin-6 and nerve growth factor upregulation correlates with improved outcome in children with severe traumatic brain injury. Raised parenchymal interleukin-6 levels correlate with improved outcome after traumatic brain injury. Biomarkers of primary and evolving damage in traumatic and ischemic brain injury: diagnosis, prognosis, probing mechanisms, and therapeutic decision making. Conventional and functional proteomics using large format two-dimensional gel electrophoresis 24 hours after controlled cortical impact in postnatal day 17 rats. Only a few of these randomized trials showed benefits in outcome, and many of them resulted in ambiguous findings. Much of the evidence for spontaneous recovery of the damaged cerebrum comes from the stroke literature, in which studies in animal models have provided cellular and molecular information, whereas systems-level data are increasingly being obtained from neuroimaging and neurophysiology studies in patients. Clinically, several basic principles of recovery have been identified: most spontaneous recovery typically occurs within 3 to 6 months, cognitive deficits are more likely than motor deficits to show further gain beyond this point, the rate of recovery is inversely proportional to the severity of the deficit, and recovery patterns vary between types of deficits in the same patient. These mechanisms can be generalized to three basic categories: plasticity of intact networks, repair of damaged circuitry, and replacement of lost neurons. Even though processes such as synaptic sprouting, unmasking of dormant circuits, and the development of new polysynaptic connections can enable function, plasticity can also result in abnormal function, as occurs when posttraumatic epileptic seizure foci or neuropathic pain is produced. Recovery also strongly depends on the type of injury,6 and the relationship between age and functional outcome is different within pediatric and adult age groups. Work in animal models has shown that focal damage in the adult brain can lead to a number of molecular and cellular changes, in both perilesional and remote brain regions, that are normally seen only in the developing brain. Focal damage is characteristically seen around hemorrhagic lesions such as contusions within the gray matter or at gray-white matter junctions. These lesions are usually located at the frontal and temporal poles and in the orbital frontal cortex. Although some of these mechanisms attenuate acute damage at the expense of future regenerative capacity, others retain the potential to participate in therapeutic interventions. Traditional strategies for treating traumatic brain injury focus on reducing sequelae of the primary brain insult (orange arrows) to salvage acutely threatened tissue, whereas restorative strategies introduce interventions that support spontaneous and directed repair of neural circuits (blue arrows) to improve functional recovery. These findings support the idea that the beneficial effects of astrocytes at the site of an injury probably occur early in the injury response, whereas subacute formation of the glial scar hinders regeneration. The beneficial effects of an astrocytic response include secretion of neurotrophic factors, regulation of metabolic factors (particularly important in times of stress), and maintenance of homeostatic levels of neurotransmitters. Therapeutic interventions, however, must account for changes in the injury microenvironment that encompass barriers to both functional reconnection and opportunities for repair (Table 343-1), as discussed in the following sections. This response is partially represented in the form of "microglial stars" and "perivascular cuffing" in human pathologic specimens. In addition, the hippocampus ipsilateral to the cortical contusion is capable of a significant plasticity response, but synapse replacement in this area does not necessarily result in significant improvement in spatial learning. The adult neural stem cell niche: lessons for future neural cell replacement strategies. Increased cell proliferation in neurogenic regions after experimental traumatic brain injury. These cells are clustered mainly in the subgranular zone, as would be expected at this time point (B, arrows). Similarly, BrdU labeling in the ipsilateral subventricular zone of sham animals (C) significantly increases after injury (D, arrows). Cell proliferation and neuronal differentiation in the dentate gyrus in juvenile and adult rats following traumatic brain injury. Patch clamp studies have demonstrated that such BrdU cells exhibit neuronal electrophysiologic properties,72 and anatomic integration of these new neurons into host tissue has been shown by retrograde tracer labeling and synaptophysin triple-label immunohistochemical techniques. In humans, in vivo dentate gyrus neurogenesis was demonstrated on histologic sections obtained from patients who had been administered BrdU for diagnostic purposes. Labeled cell bodies were also frequently enveloped by a synaptophysin "lattice," as described previously,77 thus suggesting the formation of synapses onto the somata of newborn neurons.

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A variety of such carriers are in clinical use symptoms mono chloromycetin 250 mg overnight delivery, each with its own advantages and disadvantages. It is extracted on first pass by the brain, where it becomes fixed for several hours by conversion to a hydrophilic compound in the presence of intercellular glutathione. The rapid clearance of 133Xe from the brain has the advantage of allowing repeated studies within a short interval but unfortunately requires dynamic instrumentation, which has the significant disadvantage, when combined with the low energy of the emitted photons, of rendering poor spatial resolution of the resulting images. The positrons travel up to a few millimeters through tissue before eventually becoming annihilated by collision with an electron, in the process simultaneously emitting two 511-keV photons (gamma rays) traveling at 180 degrees to each other that are registered by a ring array of external detectors. The detector electronics are designed in a manner to recognize the close temporal coincidence of two detection events as the result of one annihilation event. The trajectories of each pair of photon emissions can then be used to calculate the point of origin of each annihilation event. The coincidence events are stored in arrays corresponding to projections through the patient and reconstructed with standard tomographic techniques to generate a map of radioactivity as a function of location. The more intense the radioactivity, the greater the concentration of radiotracer in an area of interest. This tracer has a very short half-life (2 minutes), so a bolus injection provides a snapshot that can be repeated, if desired, every 12 to 15 minutes. It can be performed with a variety of pulse sequences, the simplest being the application of a 90-degree radiofrequency pulse called free induction decay, which is then converted to a spectrum by a Fourier transformation. The spectral chemical shift is measured in parts per million and is a characteristic of the variation in resonance frequency. Its specific dependency on the chemical microenvironment of a particular nucleus makes it resemble a "fingerprint" of the analyzed substance. The main limit on the wealth of diagnostic information that can be obtained is the duration of the examination. However, it is susceptible to movement artifact and is contraindicated in patients with ferromagnetic implants. It is a common disorder that occurs in patients with cardiac arrest, stroke, and subarachnoid hemorrhage and often complicates traumatic brain injury. When severe, it causes neuronal death in the affected areas, and the end result is often death or permanent neurological disability. This section discusses how ischemia perturbs cerebral function and metabolism and the molecular mechanisms through which an ischemic insult might cause brain damage. Subatomic particles such as protons behave like a spinning charge and induce microscopic loops of electric current. The nucleus of hydrogen contains a single proton and is described as having a half-integer spin. As a result, it has a very small magnetic field, or magnetic moment, that aligns itself either parallel or antiparallel to the direction of a strong external magnetic field with a circular oscillation of a certain frequency. When electromagnetic energy in the form of a radiofrequency pulse is delivered at this frequency, the hydrogen atoms are excited by absorption of this energy, which causes their magnetic moments to line up in the same direction. When the external energy is turned off, the absorbed energy is released, and the magnetic moments return to their previous orientations. Because there are regional and cellular differences in the inherent susceptibility of brain cells to ischemic injury, there is nonuniformity in both the degree and pattern of neuronal loss in sustained global ischemia. For example, the longest period of experimental cardiac arrest that can be sustained with good neurological recovery is 12 minutes. This usually occurs in the context of an arterial occlusion, most commonly from thrombosis in situ or thromboembolism, but may also occur when the integrity of the vessel is compromised, such as in dissections and hemorrhage. It typically produces a less severe but more sustained insult than that caused by nonfatal global ischemia. Focal ischemia is often permanent, but spontaneous lysis of an occluding thrombus may lead to reperfusion of an occluded artery. A dramatic illustration of such reperfusion is provided by cases of transient ischemic attack. Experiments in animals suggest that it is possible for short-lived focal ischemia to produce subtle lesions in which there is only selective loss of individual neurons. Thus arose the original concept of the "ischemic penumbra" as a region of potentially salvageable brain tissue that is perfused in a narrow range between the thresholds for electrical impairment and irreversible morphologic compromise. The upper and lower of these principal flow thresholds have accordingly become known as the "penumbral" and "infarction" thresholds, respectively. Protein synthesis begins to fail at less than 50 mL/100 g per minute, tissue lactate levels start to rise at 35 mL/100 g per minute, neurotransmitter release and disturbance of energy metabolism occur at approximately 20 mL/100 g per minute, and finally, terminal depolarization and concomitant massive potassium efflux occur at 6 to 15 mL/100 g per minute (Table 359-2). It is generally accepted that in focal ischemia there is a peripheral area of the initial lesion that may be prevented from progression to infarction by reperfusion or pharmacologic intervention. However, prevention of ischemia is not synonymous with restoration of normal physiology and there may be persistent abnormalities of ion homeostasis and thus electroencephalographic signal changes. The penumbra has maximal volume at the onset of ischemia, after which it progressively shrinks with time. Despite the critical decline in perfusion in the penumbra, its level of local glucose metabolism tends to be maintained at normal levels, which results in marked elevation of the local glucose metabolism/blood flow ratio-a sign of metabolismflow uncoupling. Mechanisms of Ischemic Brain Injury A great deal of our knowledge about the pathophysiology of stroke is derived from experimental research on animals and cell cultures. Such research has revealed that cerebral ischemic injury is the culmination of an extremely complex process involving a cascade of biochemical pathways evolving over a period of many hours or even days. Much remains to be elucidated, but it is clear that the elaborate interactions between these pathways facilitate many potential routes to brain cell death. Essentially, when a cerebral artery is occluded, the brain is deprived of glucose and oxygen, energy failure occurs, and ionic gradients are lost. Membrane depolarization causes the mass discharge of excitatory amino acids, predominantly glutamate, which binds to postsynaptic receptors and promotes the accumulation of excessive calcium levels within cells. Mitochondrial dysfunction ensues and leads to secondary energy failure and additional generation of free radicals, which further compromises the cell by attacking proteins, lipids, and nucleic acids. After a brief overview of calcium homeostasis, the principal mechanisms behind these events are discussed. It should be noted that the order of discussion does not indicate a strict temporal sequence of these events. RegulationofCellularCalcium [Ca2+]i is tightly regulated within narrow limits by multiple mechanisms. One determinant of [Ca2+]i is the balance between passive influx and active extrusion across the plasma membrane. Other regulatory mechanisms control movement of Ca2+ between the endoplasmic reticulum and the cytosol and between mitochondria and the cytosol. Conversely, the normal efflux pathway for mitochondrial calcium involves Na+dependent and Na+-independent secondary active transporters, which are substantially slower than the uniporter. More commonly, ischemia is incomplete, and when the oxygen supply is critical, greater reliance is placed on anaerobic metabolism. This affects neurons before astrocytes because the former have higher energy demands. This leads to the opening of voltage-gated ion channels, thus permitting the influx of Na+, Ca2+, and Cl- and the efflux of K+ along concentration gradients previously established by primary and secondary active transport. The influx of Na+ and Cl- is accompanied by osmotically obligated water, resulting in osmolytic damage. This cell swelling is not considered to be a principal cause of cell death in vivo because of the limited Na+, Cl-, and water content of extracellular fluid (about 20% of tissue volume). In the penumbra, the catastrophic events of the core do not occur because tissue energy status is nearly normal or relatively well preserved. Nevertheless, cell death eventually ensues if blood flow is persistently depressed. There is experimental evidence from rodents that the occurrence of repetitive peri-infarct depolarization may ultimately lead to terminal depolarization. Instead, cell death in the penumbra has been attributed to a host of secondary phenomena triggered by acidosis, excess glutamate signaling, and cytosolic Ca2+ overloading. The glutamate-stimulated increase in free [Ca2+]i is normally promptly terminated by reuptake of glutamate into astrocytes by Na+-glutamate cotransporters. Thus, impaired glutamate uptake and enhanced glutamate release combine to cause increasing concentrations of extracellular glutamate, abnormal prolongation of glutamate signaling, further cellular Ca2+ influx, and everincreasing elevations in free [Ca2+]i. Initiation of this positive feedback loop is crucial to the theory of glutamate-mediated excitotoxicity. The first two mechanisms have been found to contribute to intracellular Na+ and Ca2+ overload in cerebral ischemia. In fact, under extreme ischemic stress, endoplasmic reticulum Ca2+ stores are discharged into the cytoplasm, thereby aggravating the cytosolic Ca2+ overload.