A rare case of extramedullary-intradural hemangioblastoma in the thoracic spine.

STUDY DESIGN.: Case report. OBJECTIVE.: To present a rare case of extramedullary-intradural hemangioblastoma in the thoracic spine and to review the literature on this condition. SUMMARY OF BACKGROUND DATA.: Spinal hemangioblastoma is rare, and moreover, there is seldom purely extramedullary-intradural hemangioblastoma of the spinal cord and there are few reports on histopathological features of spinal hemangioblastoma. METHODS.: A 65-year-old Japanese woman presented with gait disturbance and numbness below the trunk that had gradually worsened, and finally she was unable to walk by herself. Physiologic and neurologic examinations at admission revealed severe transverse neurologic defects, with no sign of von Hippel-Lindau's disease. Radiologic methods showed an extramedullary-intradural mass at Th4-5. A diagnosis of extramedullary-intradural spinal tumor was done, total tumorectomy was performed with recapped laminoplasty. RESULTS.: The patient's neurologic condition gradually improved after the operation. The immunohistopathological findings revealed the diagnosis of hemangioblastoma. CONCLUSION.: A rare case of extramedullary-intradural spinal hemangioblastoma was reported. The immunohistopathological findings were helpful for making a final diagnosis.

Rest-induced suppression of anterior horn cell excitability as measured by F waves: comparison between volitionally inactivated and control muscles.

To test the hypothesis that the anterior horn cells become hypoexcitable in the absence of central drive, we recorded F waves simultaneously from the first dorsal interosseous (FDI) and the abductor digiti minimi (ADM) before and after volitionally inactivating one muscle (target) while periodically contracting the other muscle (control). In 14 healthy subjects, F waves recorded from the target muscle showed a progressive decrease in persistence and amplitude (whether counting all 100 trials or only detectable responses) after muscle relaxation for 1, 3, and 6 hours, followed by a quick recovery upon brief muscle contraction. We conclude that volitional inactivation suppresses the F waves of the target muscle without equally affecting the control muscle innervated by the same nerve. The history of activity of a muscle should therefore be taken into account in clinical testing, especially when the study of a paretic muscle shows abnormal F-wave excitability.