Alternatively, of the 27 patients who were initially myelopathic and refused to undergo surgery, 44% experienced worsening of their neurological status during the study period. Lawrence and colleagues at Berkeley treated pituitary targets with multiple proton cross-fire arcs from each side of the head, with the beams being oriented to avoid dose overlap in normal tissue but intersecting at the center of the target. The senior author strongly believes that before patients undergo any other treatment for rheumatoid involvement of the craniocervical junction, an attempt should be made to align the osseous anatomy to relieve the neural compression. Such markers include products secreted by osteoclasts, as well as collagen breakdown products. We believe that this approach should be limited to metastases, chordomas, and plasmacytomas that affect the axis and atlas vertebrae. The error presented does not represent a linear error but rather a volumetric calculation comparing the spacing of registration points in the surgical field to the spacing of the corresponding points in the image data set. The Nurick classification is composed of six grades (0 to 5) based on the severity of radiculopathy and myelopathy. High-resolution trigeminal nerve imaging is necessary for accurate radiosurgical targeting. Anterior and posterior lumbar interbody fusion techniques were described by Burns40 and Cloward,41 respectively. Postpolio syndrome is defined as the new onset of muscle weakness, pain, and fatigue 30 to 40 years after a patient recovers from acute paralytic poliomyelitis. Patients who are neurologically intact with an unstable spine are less controversial regarding the timing of stabilization. The abdominal contents are then returned to their anatomic position to prevent intestinal torsion and obstruction. Once the tumor is visualized, visceral, vascular, and neuronal structures must be identified and protected. End plate sclerosis as a result of aging and degeneration basically blocks the pores that allow diffusion of nutrients across the vertebral body end plate into the disk space. Spinal Lesions Robotic radiosurgery provides an important new tool for treating a broad spectrum of spinal lesions with the same measure of accuracy and conformality that characterize standard framebased intracranial radiosurgery. Huddart and coworkers found that age younger than 65 years, no previous hormonal therapy, and a single level of compression were factors predictive of better outcome. Surgical management involves complete resection in the presence of symptomatology. Another seldom-used technique of posterior cervical instrumentation is the interlaminar or Halifax clamp. Decisions about the length of the construct and the need for anterior reconstruction in thoracolumbar fractures have been addressed, for example, by the load-sharing classification of McCormack and colleagues. Real-time continuous intraoperative electromyographic and somatosensory evoked potential recordings in spinal surgery: Correlation of clinical and electrophysiologic findings in a prospective, consecutive series of 213 cases. However, performing a myelogram can cause neurological worsening if it is done in the presence of a high-grade block rostral to the puncture. The lateral extracavitary approach allows the tumor to be followed from the foramen into the psoas muscle. Patients are recommended to stay in a halo for 3 months postoperatively, and then changed to a hard collar for 4 to 6 weeks thereafter. One study indicated an increased fusion rate of approximately 85% to 95% for pedicle screw instrumented dorsolateral fusion, and an increase in smokers from 66% to 83%. The Roy-Camille technique resulted in a 34% rate of facet joint violation, whereas the Magerl technique resulted in a 0% rate. Although a second malignancy is a greater concern in children, higher doses of radiation are associated with reduced vertebral body bone growth17 and increased risk for muscle and soft tissue hypotrophy, which can result in reduced paraspinal support in an already unstable spine. Recurrent herniation may pose a diagnostic challenge because imaging studies will demonstrate significant postoperative changes in the epidural space at the operated level, such as epidural scar tissue, adhesions, and bony hypertrophy. The growth of medical technologies has enhanced the ease of detection and the options for definitive management of spinal infections. Although 125I low-activity seeds can be applied to tumor of any size and are relatively inexpensive ($3200 is the cost of a typical implant), GliaSite is limited to tumors less than 6 cm in diameter because of limitations in balloon size and can cost $11,000 for a typical implant (see Table 253-1).
Initially, mobilization of the great vessels can be accomplished carefully by either the spine surgeon or an approach (general or vascular) surgeon. If motion-preserving decompression with intrasegmental implants is planned, such as a laminaplasty with plate reconstruction, the lateral masses are exposed while taking care to preserve the facet capsules. Another observation from this analysis is that an obese patient, whose center of gravity is shifted farther anterior, will have more difficulty coping with compromised dorsal musculature than a fit patient. The recommended screw trajectory is directed 15 degrees medially and parallel to the adjacent vertebral end plate. In addition, a historic and influential publication from Schneider and associates in 1954, which first described central cord syndrome,64 reported several poor outcomes arising from early decompression. Also of note, in a healthy cervical spine, the height of the vertebral body is slightly greater anteriorly. Performing this step first minimizes any independent motion between C1 and C2 during navigation and makes tap and screw insertion easier. Stereotaxy is defined as the localization of a specific point in space using three-dimensional coordinates. This may require pragmatic shifts in regulation, such as not requiring demonstrated efficacy of each individual component and a focus on the efficacy and safety of the combined components. The spinal canal can be decompressed by resection of both the posterior and anterior elements. Management of the dural base is the most controversial aspect of treating spinal meningiomas. An expanding surgical armamentarium of open and thoracoscopic approaches is available to manage thoracic disk herniation. An essential requirement for spine radiosurgery is the ability to accurately determine the spinal cord dose associated with a planned treatment so that an overdose to the cord can be avoided. Following preparation of the occipital bone, bone struts or contoured metal rods are fixed to the occiput by twisting the wire tightly and then fixed to the posterior elements of the cervical spine with wire by the following techniques. Although homogeneity is suggested to be advantageous mathematically, its translation into better clinical outcomes after radiosurgery remains to be proved. Cortical bone is dense, rigid tissue that biomechanically is responsible for resisting torsional and shear loads. By ideally imparting some combination of load bearing to the vertebral column and load-sharing properties through the graft site, plating systems protect the neural elements from trauma while facilitating the development of a fusion response, respectively. Analogous to the anterior plating constructs used in the cervical region, ventral and ventrolateral instrumentation is often used to provide rigid internal fixation as well as to load-share with a strut graft following thoracic and lumbar corpectomy or after anterior lumbar discectomy and interbody fusion. Diagnosis relies on laboratory investigation, radiographic studies, and tumor biopsy results. Benefit over placebo was not demonstrated in any treatment group, although it is quite likely that this study was also underpowered to reveal a therapeutic effect. After that report, the most commonly used surgical approach to the cervical spine was the posterior midline, and it was primarily used for nondegenerative pathologies. Muscular power is fully retained, and the ataxia is related to the sensory deficit. A thermoplastic Minerva body jacket appears to limit "snaking" of the cervical spine more effectively than the halo orthosis does. A standard laminectomy, which should extend at least one segment above and below the solid tumor component, is performed. Determination of Target Volume or Volumes Target determination is an important step in making a conformal plan. Kaiser Reconstruction of the anterior thoracic spine has dramatically changed in the past several decades. However, patients with enteropathic arthritis more commonly have peripheral joint involvement (10% to 20%), followed by sacroiliitis (10%) and spondylitis (3% to 4%). Ideally, a nonexpandable graft should be slightly longer than the relaxed corpectomy site so that retraction of the distracted ligaments will hold the graft in place.
Diseases
Administration of estrogen to postmenopausal women decreases bone loss, whereas estrogen deficiency results in increased bone resorption. The patient is placed in a soft cervical collar for 2 to 3 weeks, postoperatively. Schwann cell precursors exhibit increased survival, migration, and integration after transplantation as compared to adult nerve derived Schwann cells. While shifting the frame laterally, it is important to ensure that enough space is available on the contralateral side to allow positioning of the fiducial box on the base ring of the frame. There is evidence of rotation between the spinal segment above the injury and that below such that on a lateral radiograph, one segment appears in a true lateral projection and the other is oblique. Besides posterior, completely endoscopic cervical laminoforaminotomy, an anterior endoscopic cervical microforaminotomy and diskectomy technique has been described. Fixation in lordosis unloads the anterior disk and increases force on the posterior annulus and facets. Causes of instability include, but are not limited to trauma (including occipitoatlantal dislocation), rheumatoid settling, basilar invagination (primary or secondary), neoplastic (primary or metastatic), congenital abnormalities. Instead of incising the diaphragm circumferentially from the anterior chest wall, the 11th and 12th rib attachments to the diaphragm are dissected subperiosteally through a smaller, more caudal diaphragmatic opening. Despite technologic advances, bony fusion is still the end goal of instrumentation in the majority of cases, with the hardware serving to stabilize the spine and promote fusion. Afterloading techniques with machines that automatically load the radioactive sources and the use of low-energy isotopes have greatly increased radiation safety. Imaging should be carried out without and with the administration of paramagnetic contrast agents. The toxicity associated with radiosurgery for meningiomas is mainly due to symptomatic edema or damage to cranial nerves. Posterior and circumferential approaches are the mainstay of treatment for older adults and adults with rigid curves. It is best to use a power saw when harvesting structural grafts, because osteotomes can cause microfractures. Patients with craniocervical dissociation may have normal results on motor examination, or they may display deficits, including vegetative posturing responses, cruciate paralysis, or quadriparesis. If the osteotomy is not completely closed, one should check for intervening residual bone fragments, inadequate rod contouring, or subluxation of the proximal elements. The recommended screw placement is 10 degrees medially and parallel to the orientation of the adjacent disk space in the sagittal plane. The formation of carbide tends to weaken the material and therefore allows a combination of both corrosion and stress to degrade the material. Patients with more than three levels of compression are generally treated by posterior decompression, especially with preserved lordotic curvature. Conversely, retrograde intraspinal extension of a paraspinal schwannoma usually remains epidural. In general, if a thoracic pedicle screw crosses the midline in the anteroposterior view, there is a high risk for violation of the spinal canal. Early treatment of mild to moderate myelopathy, especially in younger patients, may prevent the development of severe irreversible neurological deficits. Notably, 10 of 13 patients developed significant neurological deficits in a series, 4 of which were permanent. Hence, in a child, a transpalatal approach to the clivus and the sella would be considered before a sublabial transsphenoidal or a maxillary drop-down procedure, with the goal of avoiding damage to the growth centers. Managment of chronic lower back pain is a substantial burden to the surgeon and society. In the cervical cord, decompression may be performed by either closed or open means. When dermatomal, the pain is lancinating and often unilateral, but it may be bilateral in some cases. Adjuvant treatments, such as radiation therapy and chemotherapy, will adversely affect fusion potential. RadiosurgeryTechniquefor TrigeminalNeuralgia Stereotactic radiosurgery is performed under local anesthesia. Less often, adult diskitis results from hematogenous spread secondary to intravenous drug abuse or debilitating disease. Four-Level anterior cervical discectomy and fusion with plate fixation: radiographic and clinical results.
In these conditions the anatomic site of involvement in the ligament is the tendinous insertion into bone-the enthesis. Another potential cause of a disk-osteophyte complex is calcified herniated disk material. Frequently, the airway can be established by using the chin lift or jaw thrust technique to bring the tongue forward. This disk could be approached from an anterior, lateral, or partial facet-sparing transpedicular approachwithoutfusion. Some authors, however, prefer the anterolateral approach for cervical schwannomas below C2 because the facet is preserved and the vertebral artery can be controlled early. Patients with newly diagnosed, untreated prostate cancer and spinal metastases with spinal cord compression may be effectively treated with hormonal therapy followed by radiation. Osteoclasts then release hydrogen ions, which lowers the local pH and induces dissolution of hydroxyapatite. In this procedure, en bloc spondylectomy with anterior and posterior spinal reconstruction is performed through an all-posterior approach. Techniques for the operative management of thoracic disc herniation: Minimally invasive thoracic microdiscectomy. Care must be taken to avoid excessive removal of cortical bone, which may lead to unnecessary structural compromise of the recipient site. A mild reverse Trendelenburg position allows the lung to fall away from the apex of the pleural cavity. The costovertebral triangle is the key to unlocking the spinal canal and visualizing the nerve roots, dura, and spinal cord. The remaining axial rotation is evenly distributed among the subaxial vertebrae, but the middle and lower (C4-7) segments provide the most motion, partially because of the orientation of their facets. All patients remained neurologically stable or improved after surgery, and three of six nonambulators regained ambulatory function. If there is a question about the adequacy of the airway, intubation should be performed before the patient is loaded in the transport vehicle because urgent intubation en route can be difficult and dangerous. It is important to identify occult intradural lesions early, because significant neurological deficits may not be reversible. Most spinal meningiomas are entirely intradural, but about 10% may be both intradural and extradural or entirely extradural. However, the use of a fine-threaded T-saw has been shown to decrease the risk for tumor contamination during pediculotomy in an animal model. Such a force is transmitted through the skull and occipital condyle to the cervical spine and results in burst-type fractures. The risk for an adverse radiation effect outside the target volume becomes problematic. This was thought to be due to direct intermittent compression and narrowing of the transverse branches of the anterior spinal artery. According to Sugar and associates,218 fluconazole may be effective when administered on a continuous basis for prolonged periods. The pars interarticularis plays a strategic role in the configuration of the spine in that it supports the anterior and posterior columns through the connection of the pedicle with the lamina and facet joints. The indication for use of the system as a fusion adjunct is to supplement onlay bone placement to promote solid arthrodesis. Alternatively, a second registration technique called surface matching can be used. With the microscope, one can better visualize the sites and sources of major impingement often attributed to hypertrophied yellow ligament or synovial cysts; it also allows clear definition of the normal dural planes. Such patients are then placed in a hard cervical collar whose use is tapered while they perform cervical strengthening exercises. The pedicle screws contralateral to the interbody exposure are connected to a rod to allow sequential distraction of the interspace. Nevertheless, the use of radiosurgery as a "lesion generator" is based on extensive animal studies that defined the dose, volume, and temporal response of the irradiated tissue. Overall, the data shown in Table 311-10 suggest that neurological outcomes achieved with circumferential decompression are far superior to those achieved with decompressive laminectomy or radiation. Associated neurological abnormalities include dementia, optic atrophy, seizures, and adrenal insufficiency.
Allograft bone also tends to have a higher modulus of elasticity, a measure of stiffness, which increases the risk for subsidence and telescoping into the adjacent vertebral bodies. Inserting pedicle screws in the upper thoracic spine without the use of fluoroscopy or image guidance. Therefore, overall bone mass decreases while the remaining bone maintains normal calcification. There are approximately three to five cases per 1000 persons each year, and the incidence increases with age. Dynamic films have been suggested as a better tool to determine whether the deformity is fixed,6,12,20,22 but one must be careful in this case to be sure there are no fractures or gross instability. Injection of polymethyl methacrylate cement by means of either technique is associated with high rates of pain relief in otherwise refractory patients. Earlier in the disease, erosions are noted at the lower end of the joint, especially over the iliac side. Intraoperatively, the surface contours are important clues for determining anatomic relationships. In other cases, surgery is contraindicated and cure is impossible because of cavernous invasion. Only after full decompression of the neural elements has been completed is any attempt made to reduce the deformity. The more important concepts in clinical evaluation, diagnosis, and management are summarized. GliaSite brachytherapy for treatment of recurrent malignant gliomas: a retrospective multi-institutional analysis. Occasionally, these patients will have painful scoliosis, which is a classic manifestation of this tumor. However, unicortical screw pullout strength at the occipital protuberance was not significantly different than that of bicortical screws at other anatomic locations. When the infection has a prominent bone component, a gibbus deformity may be clinically obvious. Once C2-3 exposure is completed, attention is turned to the entry point of the screw at C2. In 1 patient, a tracheoesophageal fistula thought to be related to doxorubicin (Adriamycin) recall developed. This system allows real-time patient tracking along six degrees of freedom and provides submillimetric precision in reproducibility of daily patient positioning. The reduced fusion potential of allograft bone increases the risk for pseudarthrosis and the formation of stress fractures. Dynamic radiographs such as flexion-extension films are very helpful for investigating the stability of the spinal column and for determining the integrity of instrumentation constructs and bone fusions. During the past 20 years, a new philosophy on the surgical management of metastatic spinal disease has emerged as a result of the poor results with laminectomy. First was the high rate of pseudarthrosis and second was the rate of sacral hook dislodgment. There are advantages and disadvantages to fractionated radiation therapy and radiosurgery. Cervical Osteotomy Simmons and colleagues described a 36-year experience with posterior opening wedge osteotomies. Given the large flexion forces that would result from the length of this construct, the decision was made to extend the instrumentation to the pelvis. A straightened cervical spine occurs when the posterior-most aspect of the vertebral body is within the gray zone. Partial resection was made in 10% of patients, and a repeat surgical procedure was required in 3% of patients. Hydromyelia and syringomyelia present with bilateral sensory loss, usually of the upper extremities; muscle weakness; spasticity; pain; incontinence; scoliosis; and kyphosis. Transarticular screw fixation between C2 and C1 requires satisfactory width of the pars interarticularis at C2 and integrity of the lateral mass of C1-that is, no compromise by atrophy, compression, or significant osteoporosis.
Syndromes
Spine involvement can occur at any level; however, low back pain is a common manifestation. Hollow monaxial screws are designed either with a cylindrical spiral blade or as a hollow-perforated cylinder. Individual anatomic and local biomechanical factors are responsible for the development of these symptoms and must be evaluated carefully on an individual basis. This step is typically performed immediately after completing either registration process. Most types of axial neck pain should respond to medical management, especially in those with a history of traumatic whiplash. Improvement in motor or sensory function (or both) was noted in 5 of 7 acute and 1 of 13 chronic patients, which led the authors to suggest a therapeutic window of 3 to 4 weeks after injury. The device must tension surrounding ligamentous structures for stability while providing indirect foraminal decompression. Because of the difficulties inherent in industry-supported translation, there has been increasing emphasis on noncommercial consortia. Physical removal of nuclear material through a percutaneous approach was reported as early as 1975. However, patients with an occupying ratio of 60% or greater fared significantly better after anterior decompression than after laminoplasty. Elsberg classified these chondroma-like lesions as ecchondrosis and local hyperplasia of the cartilage. Associated inflation of health care costs is also problematic in a group of patients who are otherwise high-functioning. This is important, especially for multilevel corpectomies, to avoid potential cord ischemia. Intraoperative and postoperative radiographs are not predictive of proper screw placement. Timing of Surgery Surgery needs to be performed on an emergency basis in patients with rapidly progressive neurological deficits. Gastrointestinal causes include malabsorptive diseases such as celiac sprue and inflammatory bowel disease. With more precise dose administration, it is becoming increasingly important to accurately delineate the radiotherapy target volumes. Cauda equina syndrome may be seen, perhaps as a result of chronic inflammation, demyelination, and fibrosis, along with the development of arachnoid diverticula. The literature contains a number of reports of familial spastic paraplegias combined with other neurological abnormalities. The development of future applications of radiosurgery will depend on our understanding of the radiobiology of radiosurgery. One can also appreciate the relationship between two or more different structures because of different signals, such as a herniated disk and nerve root. As with the Synthes system, further plate bending alters the cephalad and caudal angulations of screw placement. From biomechanical and biologic perspectives, the ideal plating system would offer a combination of static and dynamic elements. Presumably, the adjacent roots have already compensated for the function of this root. As the trends within surgery have shifted to minimally invasive, reductionist methods, the concept of definitive percutaneous treatment of disk disease has become increasingly attractive. The posterior C1-2 spine is exposed, and a wire and cable fixation procedure is carried out. With a larger volume of cancellous bone available for resistance to pullout, triangulated screws provide up to twice the pullout strength of a single pedicle screw. An anterior approach allows the surgeon to more readily address both symptom complexes.
In some elderly patients, however, it may be a more suitable alternative to an extensive operative intervention. For chordomas of the spine, either spondylectomy or intralesional extracapsular excision can be performed. Frequently, the presence of dense scar tissue leads the surgeon to err in dissecting too laterally toward the carotid sheath. Local vascular injury leads to an infiltration of acute inflammatory cells and an influx of fibroblasts. In addition, patients may present with findings associated with spinal cord compression, including myelopathy (9% to 100% of patients), weakness (41% to 100%), and bowel and bladder dysfunction (18% to 78%). During anterior decompression, the probe can be placed into the partially decompressed site to orient the surgeon to the contralateral margin of the spinal column and, more importantly, to the location of the epidural space. The basis for the efficacy of any new experimental treatment is built on excellent clinical care. The drill is now passed through the body of C2 to the fracture line, and after the surgeon is assured that the spine remains aligned, a hole is drilled to and then through the posterior apex of the odontoid. Radionuclide bone scans are usually more sensitive but less specific in detecting metastatic disease than plain radiographs. Gamma Knife Radiosurgery First introduced by Lars Leksell in 1951, radiosurgery combines stereotactic technique with highly focused radiation beams to deliver a large dose to the target while keeping a low dose of radiation to surrounding normal brain parenchyma. Various techniques have been used for measuring the degree of deformity and correlating it with the degree of correction required. For high-activity temporary implants, tumors must be less than 6 cm in maximal diameter, and because of the fear of brainstem injury, only supratentorial, subcortical locations are implanted. These therapies may preserve tissue, promote cell survival, activate neuron growth, reduce growth inhibition, decrease scarring and cavitation, and augment myelin repair, and the introduced cells may integrate within or replace neuronal circuits. Renner and associates demonstrated that injection of 3 mL of calcium phosphate significantly improves pedicle screw pullout strength in comparison to unaugmented screws. The anterior screws are placed either perpendicular to the posterior wall or slightly dorsal. Additionally, in select situations of posterior or pure longitudinal craniovertebral disassociation, a value of less than 1 may be obtained. Spinal orthotic devices work by limiting physical movement to a greater or lesser degree, depending on device design and stiffness, fit, patient anatomy, level of injury, and the nature of the instability being treated. Prognostic factors for functional outcome and survival after reirradiation for in-field recurrences of metastatic spinal cord compression. Previous treatments (radiation therapy, microsurgery) and histologic grading of the meningioma are also taken into consideration before radiosurgery. Fehlings and Vaccaro of the University of Toronto and Thomas Jefferson University. Fusion Once the diskectomy or corpectomy is performed, the end plates are prepared to enhance bony fusion. Of the 39 patients, one third had peripheral disease involving psoriasis or inflammatory bowel. AtlasFractures Isolated fractures of the atlas account for approximately 5% to 10% of cervical spine injuries. In addition, by incorporating a bank of detectors, tomography can be performed while the patient is being treated. Iliac screw fixation with tricortical sacral screw placement minimizes distal construct failure and pseudoarthrosis. The most appropriate procedure and graft in a specific situation depend on a variety of mechanical factors, including the segment of spine involved, the indication for fusion, and the proposed fusion technique. The endoscope portal is best positioned posterolaterally between the middle and posterior axillary line.
Also like chordomas, the local recurrence rate approaches 100% for patients who do not undergo gross total resection. Indications for a cervical spine series include localized pain, deformity, crepitus or edema, altered mental status, neurological dysfunction, or head injury. The decision to treat a lumbar spine trauma patient operatively is based on multiple factors. Results were similar when comparing the three fusion strategies, although instrumented fusions tended to heal more quickly. Accordingly, ventral compressive pathology is best addressed by direct ventral decompression and fusion, and vice versa. For these reasons, weekly or biweekly imaging during treatment is advisable to ensure that the enlarged cyst remains within the treated volume. Fungal infections caused by Blastomyces dermatitidis, Cryptococcus neoformans, Coccidioides immitis, Aspergillus, and Histoplasma capsulatum, as well as bacteria of the genus Brucella, Actinomyces bovis, and Actinomyces israelii, can also lead to granulomatous disease of the spine. Recognition of the possibility of these infections in their various endemic regions is a key to diagnosis. In contrast, metastatic tumors to the brain are a commonly encountered clinical situation, but patients have even poorer outcomes than those with primary brain tumors. Specifically, pelvic inlet views and obturator views may help to guide the pelvic screw down the intended trajectory. However, it is important to evaluate for pseudarthrosis in a patient who does not have a good outcome following a spinal arthrodesis procedure. Newer data for adult patients show 5-year survival rates of up to 80%, although 10-year survival rates drop off to 40% to 50%. The two aspects of stainless steel that make it most popular are its high ductility and malleability. In an extended exposure of the lower cervical spine, the omohyoid muscle may be in the surgical field. When 100 consecutive patients with disk disease, lateral recess stenosis, and central stenosis were evaluated, all three groups of patients demonstrated comparable complaints of pain at rest, pain at night, and pain on coughing. Unlike the management of metastatic spinal tumors, the goal of treatment of a primary spinal tumor is to achieve lasting local tumor control for long-term survival or possible cure. After the dimensions of the resection defect have been measured, a sterile Silastic tube is cut 5 to 6 mm longer than the end plates at the margin of the vertebrectomy defect. Other noteworthy features of the C1-2 joint include the absence of a true intervertebral disk and relatively loose capsular ligaments,12 evolution of the ligamentum flavum into a weaker atlantoaxial membrane, a rich blood supply from branches of the vertebral and carotid arteries, and an increased spinal canal diameter. Invited submission from the Joint Section Meeting on Disorders of the Spine and Peripheral Nerves. Infection usually occurs after intraoperative contamination,147 and the typical causative organisms are skin flora- commonly S. This fine, thin collection of nerves is most commonly found arching over the left iliac artery crossing the L5-S1 disk space. Elderly patients have a propensity for other medical illnesses that warrant a minimally invasive approach. A biomechanical cadaveric analysis of polymethylmethacrylate-augmented pedicle screw fixation. Type I fractures are bilateral pars interarticularis fractures with less than 3 mm of displacement of C2 on C3 and no angulation. InMotion Artificial Disc (Depuy Spine) the next-generation Charite device has redesigned end plates and a no-impaction application technique. As in adults, previous acquired knowledge is usually preserved, but there is a deficit in acquiring new skills. A close follow-up with postoperative imaging is essential and may be needed every 3 months for the first year, especially for aggressive lesions. It is this axial view provided by image-guided navigation that makes it superior to fluoroscopy for spinal screw fixation procedures.
In adults, such injuries were initially ascribed to hyperflexiondistraction with immediate reduction by muscular action or transient disk prolapse during forced flexion. Other Anterior Approaches (Cervical Disk Arthroplasty, Anterior Endoscopic Microforaminotomy) Evolution in anterior cervical spine surgery includes the use of disk arthroplasty implants (discussed further in Chapter 293) and anterior endoscopic techniques. Eight patients had significant postoperative complications, which include two instrumentation failures and one wound dehiscence. The vertebral bodies are distracted, and the graft is inserted with a mallet and impactor. Complications of cervical discography: analysis of 4400 diagnostic disc injections. Studies of patients managed conservatively demonstrate wide-ranging growth rates (between 0 and 30 mm/yr), but with a median growth rate ranging from 0. The complication rate associated with harvesting autologous bone from a separate site, primarily the iliac crest, ranges from 9. Primates showed anatomic plasticity and behavioral recovery, although the injury model, C7 hemisection,167 is optimized to show this effect and is not similar to human contusive injury. It should be emphasized that disk degeneration and disk herniation are closely related but not synonymous. In the latter case, it can be used to verify the extent of osseous decompression or cervical alignment in three dimensions or to confirm appropriate placement of instrumentation. When a corpectomy is performed, diskectomies are performed above and below the corpectomy sites to obtain a visual gauge of where the spinal canal lies. Before closure of the osteotomy, a Kerrison rongeur is used to further enlarge the central canal and remove any bone fragments that may interfere with the exiting nerve roots. Embryology the development of the spinal cord and vertebral column can be divided into three general periods during gestation: embryogenesis (weeks 2 to 3), neurogenesis (weeks 3 to 6), and skeletogenesis (weeks 9 to 24). It should be noted that these goals can be accomplished only from a posterior approach, and consequently, indications for anterioronly approaches are relatively limited in the setting of adult scoliosis of the lumbar/thoracolumbar spine. Thus, the point of maximum stress-and therefore the point of failure-is usually at the screwplate juncture. With en bloc laminectomy or "lobster tail" removal of the lamina, bilateral gutters are drilled along the lamina-facet junction across the segments that require decompression. The most advanced and optimal surgical treatment to achieve this goal is wide tumor excision with en bloc spondylectomy or en bloc sacrectomy. Advances in the sensitivity of imaging modalities and refinement of microsurgical skills have allowed microsurgical resection to be viewed as definitive treatment in most cases. Additionally, nonoperative management may be appropriate for patients with advanced age or significant medical comorbidities, those who are poor surgical candidates, or those who have severe chronic neurological deficits that are presumably irreversible. It is also significantly impaired after many ventral surgical approaches in which the intention is to decompress the spinal cord. Long-term follow-up after high-activity 125 I brachytherapy for pediatric brain tumors. A cursor superimposed on this image can show the position of the screw tip along the selected trajectory at millimeter increments. At last follow-up, significant pain relief was noted by 77% of patients (good response plus complete pain relief). Cervical spondylosis is a chronic degenerative process, so one should expect to see its prevalence increase significantly with age. Calcitonin binds directly to receptors on osteoclasts, which decreases adherence of osteoclasts to bone and thus inhibits their activity. Even in the absence of an imaging abnormality, occult spinal dysraphism can still have tethered cord symptoms. Samii and associates,55 in a recent review of 49 patients who had undergone resective surgeries at a single institution, came to the conclusion that complete tumor removal was accomplished in 49% and subtotally in 51%. The technical difficulty of this procedure is the accurate passage of the screw through the narrow pars interarticularis of C2. Using this approach, the insertion of four pedicle screws typically takes no more than 8 to 10 minutes, and the need for standard fluoroscopy is eliminated for most spinal screw fixation procedures. Failure of the system leads to the dissipation of the unopposed force or moment applied to the system.
It is essential to not merely repeat the previous fusion operation but to comprehensively improve on it. The close proximity of the medulla and vertebral arteries makes potentially fatal injuries seem relatively likely. The precisely defined area of intense ionization at the end of the track after the passage of protons is called a Bragg peak. Further studies by the same group showed that an artificial cervical disk replacement group exhibited kinematic and kinetic results similar to the healthy adult group. Posterior Iliac Crest the posterior iliac crest is another common autograft harvest site for spine surgery, especially for posterior fusion procedures. A single burst of activity synchronized to surgical manipulations is useful for functional identification and correlation of specific roots and typically does not result in adverse outcomes. Rarely, seizures occur in the post-treatment period, usually in patients with supratentorial lesions and in those with a history of seizure disorders. Dumbbell extension through the nerve root sleeve, however, generally necessitates resection of both nerve roots because the tumor has invaded the corresponding spinal nerve where sensory and motor fibers are admixed. This region, with its osseous articulations and ligamentous support structures, must resist forces in eight axes of rotation, including flexion, extension, bilateral lateral bending, bilateral rotation, distraction, and axial loading. Unlike the cervical spine, in which anterior access is relatively straightforward, revision surgery in the lumbar spine may present both challenging and possibly life-threatening hurdles. Intraspinal exposure is achieved through a standard laminectomy medial to the paraspinal muscles. The reaction of the body to the inevitable generation of wear debris is the third point to consider when choosing the appropriate biomaterial from which to fabricate an arthroplasty device. This heterogeneous group of malformations can be broadly categorized according to whether the malformation is open or is covered by a layer of skin. The spine has therefore evolved to adopt a curvilinear sagittal conformation-with a primary kyphotic thoracic curve compensated by secondary cervical and lumbar lordotic curves of equal summative magnitude. Anterolateral decompression for metastatic epidural spinal cord tumors: results of a modified costotransversectomy approach. RadiationToxicity Complications from the radiosurgical treatment of benign spinal tumors are rare. The carbon fiber cages that we use have a lordotic sagittal contour with the ventral surface being 2 mm larger than the dorsal surface. In another study, patients with stenosis and degenerative spondylolisthesis from 13 centers, randomly enrolled in two treatment groups, demonstrated substantial gains in pain relief and function following decompressive laminectomy with or without fusion (304 patients) compared with no surgery (303 patients). In addition, the cost of biologic therapies can be great, and there is an ethical and societal imperative to establish the cost-effectiveness of expensive therapies. Even though there is some disagreement on the prevalence of adjacent-segment disease, the consensus would suggest that it occurs in approximately 2. Local anesthesia was applied to the contact sites for placement of the fixation pins. However, certain patients with high preoperative narcotic use may require an epidural catheter for analgesia. Only a few traces are required for averaging, and the stimulation can be repeated at 0. There have been several studies of therapeutic combinations, including fetal tissue and neurotrophins. Image-guided and intensity-modulated radiosurgery for patients with spinal metastasis. Care must be taken, however, if compression is directly applied to the instrumentation; significant ventrolateral compression can create a segmental kyphosis or scoliosis. Dose prescription must take into account two conflicting considerations: the chance of obliteration versus the chance of radiation-related complications.
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