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.


CONCLUSIONS
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.
Jinnai
Takahiro
T
Department of Neurosurgery, Ohtsu Municipal Hospital, Ohtsu, Japan.
Koyama
Tsunemaro
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D004388:Dura Mater / Q000473:pathology; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D007796:Laminectomy; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000209:etiology; D018317:Nerve Sheath Neoplasms / Q000150:complications / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery; D009455:Neurofibroma / Q000453:epidemiology / Q000473:pathology / Q000601:surgery; D009456:Neurofibromatosis 1 / Q000453:epidemiology; D016518:Neurofibromatosis 2 / Q000453:epidemiology; D009463:Neuroma / Q000453:epidemiology / Q000473:pathology / Q000601:surgery; D010146:Pain / Q000209:etiology; D010292:Paresthesia / Q000209:etiology; D010524:Peripheral Nervous System Neoplasms / Q000150:complications / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery; D012189:Retrospective Studies; D013120:Spinal Cord Neoplasms / Q000150:complications / Q000453:epidemiology / Q000473:pathology / Q000601:surgery; D013126:Spinal Nerve Roots / Q000473:pathology; D013127:Spinal Nerves / Q000473:pathology* / Q000601:surgery; D016896:Treatment Outcome