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Mobile Intradural Schwannoma of the Cauda Equina 2007

General Spine

David Friedman, M.D.
Reginald Denis, M.D., Non ASSR Member
Adam Flanders, M.D., ASSR Member

Excerpta Extraordinaire

Excerpta

Highly mobile intradural spinal neoplasms are rarely identified. The few reported cases have usually occurred in the cauda equina. A 48-year-old woman presented with low back pain. Routine unenhanced MR imaging of the lumbar spine showed an intradural mass at the L2-L3 level. The patient returned nine months later for a contrast-enhanced scan that demonstrated a peripherally enhancing, intradural mass that had migrated caudally, and was now located predominantly behind the L4 vertebral body. A pre-operative localization scan obtained two weeks later showed that the mass had now migrated rostrally by a distance of 7 mm. The mass was resected and the pathologic diagnosis was schwannoma. Mobility of an intradural spinal neoplasm to the extent seen in this case is very rare; the few reported cases have usually been schwannomas of the cauda equina. There is one case report of a filum ependymoma that migrated 7 cm. Migration of cauda equina tumors secondary to positioning on the operating room table has been described, but is also considered rare. The distance of tumor migration in this case clearly exceeds the small amount of normal mobility of the cauda equina with positioning. Possible mechanisms for migration of schwannoma include elongation of the nerve root by tension resulting from tumor weight, and increased length/mobility of the nerve root involved by the schwannoma. The significance of mobility of an intradural spinal neoplasm is clear; migration of a lesion with respect to the pre-operative MRI examination may necessitate additional laminectomy and modification of the site of durotomy. To avoid this complication, in patients with neoplasms of the cauda equina, a pre-operative MRI examination should be obtained in very close proximity to the time of surgery; intraoperative ultrasound may also be of benefit.

References

1. Friedman JA, Wetjen NM, Atkinson JLD. Utility of intraoperative ultrasound for tumors of the cauda equina. Spine 2003;28:288-290 2. Varughese G, Mazagri R. Mobile tumours in the lumbar spinal canal: a diagnostic problem. Can J Surg 1997;40:59-63 3. Isu T, Iwasaki Y, Akino M, Nagashima M, Abe H. Mobile schwannoma of the cauda equina diagnosed by magnetic resonance imaging. Neurosurgery 1989:;25:968-971 No disclosures.

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