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Object: The goal of this study was to elucidate the pathophysiological features and clinical significance of the magnetic resonance imaging-documented small intramedullary high signal intensity known as "snake-eye appearance" (SEA) in cases of compressive myelopathy such as cervical spondylosis or ossification of the posterior longitudinal ligament., Methods: One hundred forty-four patients with compression myelopathy who underwent surgery between 1998 and 2000 were selected. Intramedullary high signal intensity was found in 79 cases and was divided into two types, SEA and non-SEA (NSEA). The Japan Orthopaedic Association (JOA) scoring system was used for evaluation of pre- and postoperative neurological status. In nine cases of SEA autopsy was performed and specimens were histologically analyzed. The improvement ratio determined by JOA score was 32.2 +/- 15.1% in SEA, 47.1 +/- 12.1% in NSEA, and 50 +/- 18.3% (p < 0.01) in control cases in which high signal intesity was absent. There were significant differences among SEA, NSEA, and control groups. In a separate group of nine patients who died of unrelated causes, histological examination showed small cystic necrosis in the center of the central gray matter of the ventrolateral posterior column and significant neuronal loss in the flattened anterior horn., Conclusions: Snake-eye appearance was found to be a product of cystic necrosis resulting from mechanical compression and venous infarction. Destruction of the gray matter accompanying significant neuronal loss in the anterior horn suggested that SEA is an unfavorable prognostic factor for the recovery of upper-extremity motor weakness.

Object: The authors conducted a biomechanical study in which they compared the uses of the Rogers interspinous and the Lovely-Carl tension band wiring techniques for internal fixation of the cervical spine., Method: An extensive biomechanical evaluation (stiffness in positive and negative rotations around the x, y, and z axes; range of motion in flexion-extension, bilateral axial rotation, and bilateral bending; and neutral zone in flexion-extension, bilateral axial rotation, and lateral bending to the right and to the left) was performed in two groups of intact calf cervical spines. After these initial tests, all specimens were subjected to a distractive flexion Stage 3 ligamentous lesion. Group 1 specimens then underwent surgical fixation by the Rogers technique, and Group 2 specimens underwent surgery by using the Lovely-Carl technique. After fixation, specimens were again submitted to the same biomechanical evaluation. The percentage increase or decrease between the pre- and postoperative parameters was calculated. These values were considered quantitative indicators of the efficacy of the techniques, and the efficacy of the two techniques was compared., Conclusions: Analysis of the findings demonstrated that in the spines treated with the Lovely-Carl technique less restriction of movement was produced without affecting stiffness, compared with those treated with the Rogers technique, thus making the Lovely-Carl technique clinically less useful.

The authors evaluated the clinical, radiological, and surgical management of ossification of the anterior longitudinal ligament (OALL) that contributed to dysphagia in a patient with simultaneous cervical ossification of the posterior longitudinal ligament (OPLL). A 57-year-old man presented with increasing dysphagia and moderate myelopathy. Imaging studies, including esophagoscopy, revealed marked esophageal compression due to OALL that extended between the C2-5 levels and significant C5-7 OPLL that compressed the distal cervical spinal cord. The use of rongeurs and a high-speed drill facilitated excision of the C2-5 OALL mass, and a routine anterior corpectomy with fusion was performed at the C5-7 level. Postoperatively, the patient's dysphagia and symptoms of myelopathy immediately resolved. The strut graft became fully fused 3 months postoperatively, as demonstrated on dynamic x-ray films, and the patient has remained asymptomatic 4 months postoperatively. Patients with dysphagia and coexisting myelopathy benefit from simultaneous surgery for resection of OALL and OPLL masses.

Object: Because of the lack of magnetic resonance (MR) signal from cortical bones, MR imaging is inadequate for diagnosing ossified lesions in the spinal canal. However, MR imaging provides important information on spinal cord morphology and associated soft-tissue abnormality. The purpose of this study is to determine the role of MR imaging in the diagnosis and treatment of patients with ossification of the posterior longitudinal ligament (OPLL) of the cervical spine., Methods: The authors reviewed MR imaging findings in 42 patients with cervical OPLL who were examined with a superconducting MR imaging system. The types of OPLL reviewed included eight cases of continuous, 21 cases of segmental, and 13 cases of the mixed type. All patients were treated surgically either by anterior (26 cases) or posterior decompression (16 cases)., Conclusions: The T1-weighted images clearly demonstrated the spinal cord deformity caused by OPLL. Associated disc protrusion was found to be present at the maximum compression level in 60% of the patients in this series. The highest incidence of disc protrusion (81%) was found in patients with segmental OPLL. Intramedullary hyperintensity on T2*-weighted imaging was noted in 18 patients (43%). The neurological deficits observed in these 18 patients were significantly more severe than those observed in the other 24 patients. Postoperative MR imaging revealed improvement in the spinal cord deformity, although the intramedullary hyperintensity was still observed in most cases. The present study demonstrates the importance of associated disc protrusion in the development of myelopathy in patients with cervical OPLL. Magnetic resonance imaging findings may be used to help determine the actual levels of spinal cord compression and to suggest the method of surgical treatment.

In this study the authors detail their experience with posterior tension-band wiring for stabilization of the subaxial cervical spine. Fifty-five patients underwent fusion for trauma (41 patients), degenerative disease (13 patients), and tumor (one patient). The fusion rate was 96% (50 of 52 patients) and postoperative immobilization was accomplished by means of a Philadelphia collar in the majority of cases. Tension-band wiring provides a stable construct that is simple to perform, requires fusion of a minium number of motion segments, and allows early mobilization with only a hard collar needed for support. The details of the technique, which has been modified from preliminary descriptions, are discussed.

This report describes a technique for exposing the ventrolateral quadrant of the spinal cord through an extended posterolateral approach that can be used in both cervical and thoracic regions. The surgical technique includes the following: 1) a midline skin incision with a transverse extension at the level of pathology; 2) unilateral division and retraction of the paraspinous muscles; 3) laminectomy and unilateral removal of facets and pedicles; 4) dural incision over the dorsal root entry zone; 5) multilevel division of the ipsilateral dentate ligaments; and 6) elevation and rotation of the spinal cord with dentate traction stiches. This technique provides exposure of the ventral root entry zone, the ipsilateral half of the ventral surface of the cord, and the anterior spinal artery. The surface of the spinal cord beyond the anterior spinal artery is not seen. This approach has been used for the treatment of seven ventrolateral spinal cord lesions: five spinal arteriovenous malformations (two Type II, one Type III, two Type IV), one hemangioblastoma, and one cavernous angioma. All the lesions were completely excised. Two patients had mild new neurological deficit after surgery, and one adolescent developed mild asymptomatic thoracic kyphosis, but no other spinal instability was observed over a follow-up period of 1 to 4 years. This operative approach provides significant advantages for ventrolateral perimedullary or intramedullary lesions of the cervical or thoracic spinal cord.

A retrospective review was conducted on the records and radiographs of six symptomatic patients and one asymptomatic patient with Forestier's disease. No other series of patients with this disease is found in the neurosurgical literature. Forestier's disease, also known as diffuse idiopathic skeletal hyperostosis (DISH), is an idiopathic rheumatological abnormality in which exuberant ossification occurs along ligaments throughout the body, but most notably the anterior longitudinal ligament of the spine. It affects older men predominantly; all of our patients were men older than 60 years of age. The disease is usually asymptomatic; however, dyspnea, dysphagia, spinal cord compression, and peripheral nerve entrapment have all been documented in association with the disorder. Five of the six symptomatic patients presented with dysphagia due to esophageal compression by calcified anterior longitudinal ligaments, and one patient developed recurrent spinal stenosis when scar tissue from a previous decompressive laminectomy became calcified. All patients responded well to surgery. Two of the four patients who underwent removal of cervical osteophytes required several months following surgery for the dysphagia to resolve. This would support the hypothesis that not all cases of dysphagia in Forestier's disease are due to mechanical compression. Dysphagia may result from inflammatory changes that accompany fibrosis in the wall of the esophagus or from esophageal denervation. Evaluation of dysphagia even in the presence of Forestier's disease must rule out occult malignancy. The authors' experience suggests that dysphagia in the setting of Forestier's disease is an underrecognized entity amenable to surgical intervention.

Six ventrally located intradural thoracic tumors were successfully resected through the posterolateral approach. This approach allows direct visualization of the ventral and dorsal boundaries of the tumor with minimal manipulation of the spinal cord. Compared to the traditional laminectomy, the operative time is increased but visualization of the tumor and spinal cord is markedly improved. Compared to the transthoracic approach, the posterolateral approach has fewer potential complications and eliminates the necessity of vertebrectomy. Neurological improvement occurred in all six patients. It is believed that this approach offers significant advantages for the treatment of ventrally located intradural thoracic tumors, and should be considered an alternative to the transthoracic approach.