病的笑い発作を生じた滑車神経鞘腫の1例

A Case of Trochlear Nerve Neurinoma Presenting with Pathological Laughter

Ⅰ．はじめに

　頭蓋内神経鞘腫は全脳腫瘍の約8%を占める良性腫瘍であり，滑車神経に発生することは稀である．特に，神経線維腫症を伴わない滑車神経鞘腫は非常に少ない．今回われわれは，滑車神経鞘腫における好発症状である複視に加え，病的笑い発作を併発した滑車神経鞘腫の1例を経験したので，外科的摘出の際のアプローチ法と病的笑い発作を来す機序を含めた考察を加え報告する．

　Trochlear nerve neurinomas are rare and solitary tumors without neurofibromatosis are extremely rare. We report a case of trochlear nerve neurinoma presenting with pathological laughter and diplopia.

　A 40-year-old male patient presented with diplopia and pathological laughter 2 months before admission. MRI showed a multicystic enhanced mass in the left tentorial incisura compressing the midbrain and the upper pons. The tumor was excised using the left trans-Sylvian approach with partial uncal resection. After excision of the tumor, the left trochlear nerve was identified on the surface of the lateral midbrain. The nerve was connected to the tumor. Pathological laughter completely resolved after the operation.

　This is the second reported case of trochlear nerve neurinoma presenting with pathological laughter. The lesion responsible for pathological laughter could be the midbrain, upper pons, diencephalon, or all of these.