Chiari I malformation accompanied by assimilation of the atlas, Klippel-Feil syndrome, and syringomyelia: case report.

BACKGROUND: Chiari I malformation, accompanied by superposed bony anomaly of the craniovertebral junction, is comparatively rare. We report a case of Chiari I malformation accompanied by assimilation of the atlas, Klippel-Feil syndrome, and syringomyelia. CASE DESCRIPTION: The patient was a 61-year-old woman demonstrating numbness of the extremities, sensory impairment, muscular weakness, and tendon hyper-reflexia. X-ray images and CT scans demonstrated assimilation of the atlas to the occipital bone, C2 and C3 fusion, abnormal passage of the vertebral arteries, and an anomalous bony mass on the right lateral mass of the atlas protruding into the spinal column. The odontoid process was also deviated to the left. Magnetic resonance images demonstrated bilateral descent of the cerebellar tonsils and syringomyelia extending from C6 to T8. Computed tomographic scans with the head rotated to the right demonstrated increased narrowing of the vertebral column caused by the right lateral mass of the atlas, and MR images confirmed exaggerated deformation of the spinal cord at the same region. This deformation manifested no neurologic symptoms, and we therefore performed foramen magnum decompression and duraplasty using Gore-Tex (W.L. Gore & Associates, Inc., Flagstaff, AZ). In the early postoperative period, neurologic symptoms improved. CONCLUSION: We believe it is important that a treatment plan for Chiari I malformation accompanied by bony anomaly of the craniovertebral junction be determined based on morphologic investigation of the region supplemented by dynamic imaging-based evaluation of instability, or a careful inspection for atypical passage of the vertebral arteries, a frequent site of complication.

Clinical characteristics of spinal nerve sheath tumors: analysis of 149 cases.

OBJECTIVE: Spinal nerve sheath tumors arise from the spinal nerve root and grow along it. There are two sites at which the growth of a tumor is restricted: the dural aperture for the spinal nerve root and the intervertebral foramen. This article describes the growth pattern of a spinal nerve sheath tumor along the spinal nerve root at various spinal levels. METHODS: We retrospectively reviewed the records for 149 patients with spinal nerve sheath tumors who were treated between 1980 and 2001. Of these, 176 resected tumors were classified into five groups according to the relationship to the dura mater and/or the intervertebral foramen. RESULTS: Strictly intradural tumors compose 8% of nerve sheath tumors of the first two cervical nerve roots. The percentage of these tumors increased gradually from the high cervical region to the thoracolumbar region, where it was more than 80%. In contrast, the percentage of strictly extradural tumors gradually decreased from the rostral portion to the caudal portion. Similarly, a percentage of tumors extending outside the spinal canal decreased from the rostral portion to the caudal portion. These changes of the growth pattern may be explained by the anatomic features of the spinal nerve roots, which have a longer intradural component at the more caudal portion of the spinal axis. CONCLUSION: The anatomic relationship of a nerve sheath tumor with the dura mater and the intervertebral foramen varies depending on the level of the tumor. This knowledge may help us to create a strategy for total resection of a nerve sheath tumor.