Faculty Bibliography

STUDY DESIGN: To establish the diagnosis of dural penetration on preoperative computed tomographic studies of the cervical spine in patients with ossification of the posterior longitudinal ligament (OPLL). OBJECTIVES: To define before surgery the pathognomonic computed tomographic findings of OPLL extending to and through the dura. SUMMARY OF BACKGROUND DATA: On preoperative computed tomographic studies, Hida et al have described the single-layer sign characterized by a solid mass of hyperdense OPLL and the double-layer sign defined by two (anterior and posterior) ossified rims surrounding a central nonossified but hypertrophied posterior longitudinal ligament. Only 1 of the 9 patients exhibiting the single-layer sign but 10 of 12 patients showing the double-layer sign had no separate dural plane identified at surgery. METHODS: Only 2 of 54 patients undergoing multilevel cervical circumferential OPLL procedures had absent dura at surgery. Computed tomographic examinations for all patients were retrospectively reviewed to determine unique signs of dural penetration. RESULTS: Dura was absent in 1 of 12 patients who had the single-layer CT sign that was additionally characterized by an irregular C angular configuration. Only 1 of 4 patients exhibiting the double-layer computed tomographic sign had absent dura at surgery. The remaining 38 patients had the smooth-layer sign, characterized by more regular margins of classic (22 patients) or early OPLL (16 patients). CONCLUSIONS: The double-layer computed tomographic sign is more pathognomonic for dural penetration than the single-layer sign. The smooth-layer sign, indicating a clean dural plane, is more typical in North American patients

Cervical laminectomy with posterior wiring and fusion is valuable for the management of cervical ossification of the posterior longitudinal ligament (OPLL), spondylosis, ossification of the yellow ligament (OYL), stenosis, and instability. Within 1.5 years, five patients averaging 73 years of age developed severe myelopathy. Dynamic radiographs confirmed an intact cervical lordosis with active subluxation and instability at one or two levels, whereas magnetic resonance and computed tomography scans showed OPLL, spondylosis, OYL, and stenosis. After multilevel laminectomy with posterior wiring and fusion and immobilization in cervicothoracic orthoses, patients fused in an average of 3.6 months. All patients improved, showing mild to moderate residual postoperative myelopathy an average of 13 months later (range, 6-19 months). With an intact cervical lordosis, laminectomy with posterior wiring and fusion was used successfully to manage five patients with OPLL, spondylosis, OYL, stenosis, and instability

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

Can simultaneous anterior and posterior (circumferential) surgery in patients with cervical ossification of the posterior longitudinal ligament (OPLL)/stenosis, achieving both decompression and stabilization, be accomplished with acceptable risk? Between 1989 and 1996, 22 circumferential procedures were performed, including an average 2.5-level anterior corpectomy with 5-level posterior wiring and fusion. These patients were severely myelopathic (average Nurick grade 3.5) and were followed for a mean interval of 22 months (range 4-52 months). Circumferential procedures required an average of 9.8 h and 3.5 U of blood transfused. Postoperatively, patients improved approximately +3.0 Nurick grades. Simultaneous circumferential surgery for OPLL/stenosis may be successfully performed in <10 h with limited blood loss.

In the cervical spine, routine and contrast magnetic resonance (MR)- and computed tomography (CT)-based studies may fail to differentiate between an ectatic vertebral artery and a solid foraminal mass. A complete cervical and lumbar Myelo-CT scan in a 67-year-old female with lumbar stenosis revealed an incidental, left-sided C3-C4 foraminal mass. A vascular lesion was suspected when the MR study revealed the lesion to be a signal void. MR angiography confirmed an ectatic C3-C4 vertebral artery loop. The possibility of a vertebral artery anomaly should be considered in patients with asymptomatic lateral and foraminal cervical lesions on CT studies. In these patients, routine MR and MR angiography are necessary to demonstrate the status of the vertebral artery in the foramen.

The clinical, neuroradiological, and surgical management of three cases of intradural disc herniations--one each in the cervical, thoracic, and lumbar regions--are presented. Intradural disc herniations comprise only 0.27% of all herniated discs. Three percent occur in the cervical, 5% in the thoracic, and 92% in the lumbar spinal canal. Those with cervical or thoracic lesions frequently exhibit profound myelopathy, whereas those with lumbar lesions demonstrate radicular or cauda equina syndromes. Although varying combinations of the MRI, non-contrast CT, myelogram, and myelo-CT scans may at times fail to accurately establish the diagnosis of an intradural disc herniation prior to surgery, the index of suspicion raised by the lack of clinical correlation with surgical findings justifies an intradural exploration.

Two patients with pain referable to the low back and sacroiliac regions had bone scans with similar findings. In each, one sacroiliac joint was "warm" (uptake on that side was slightly greater than that in the contralateral area). Ga-67 imaging also demonstrated increased uptake in the same locale. Subsequent CT scanning revealed pelvic abscesses adjacent to the affected joints. Asymmetric uptake of bone imaging agent may have been related to hyperemia and "heating" of the sacroiliac joint. Rapid defervescence with antibiotics and drainage (and no CT evidence of bone involvement) suggested that osteomyelitis was not involved in these cases.

The management of 60 patients with far lateral lumbar disc herniations operated on over a 5-year period are presented. These lesions were located superiorly within the neural foramens beneath or distal to the facet joints. The type of surgery performed in 43 of 60 (72%) of these patients was significantly altered by the presence of diffuse and lateral recess stenosis. This was better appreciated on the myelogram and myelo-CT (M-CT) studies than with the noncontrast CT and MRI examinations alone. Myelo-CT findings were particularly valuable in assessing patients who had previous surgical procedures

In six patients, operations for bilateral carpal tunnel syndromes (CTS) were performed or were about to be performed without the awareness of the presence of underlying cervical spondylo-stenosis. Only later, when symptoms of myeloradiculopathy were recognized, was the diagnosis confirmed and decompressive laminectomy performed. Because the symptoms of CTS may resemble or be masked and accentuated by the cervical disorder, patients with the presumed diagnosis of bilateral CTS should undergo appropriate critical neurologic, electrodiagnostic, and neuroradiologic (magnetic resonance imaging, computed tomography, myelo-computed tomography) assessment. If these guidelines are followed, the radiculopathy caused by cervical pathology will be appropriately recognized and treated, possibly averting the need for carpal tunnel decompression or modifying treatment

Spinal stenosis should be considered in the differential diagnosis of disc disease when evaluating an adolescent presenting with unrelenting back and leg pain. Although they typically exhibit mechanical signs alone without neurological findings, they nevertheless may prove more vulnerable to rapidly progressive neurological changes. If motor deficits occur, protracted courses of conservative care should be avoided, and proper surgical management considered. Our recent experience with a 14-year-old boy with disc disease and stenosis indicated that aggressive surgical management facilitates a rapid return to an asymptomatic existence