両側慢性硬膜下血腫を伴い，滑車神経麻痺を呈した特発性低髄液圧症候群の1例

Spontaneous Intracranial Hypotension Associated with Trochlear Nerve Palsy and Bilateral Chronic Subdural Hematoma

　要旨　症例は71歳男性。起立性頭痛が生じ，頭痛が2週間持続したあと両側慢性硬膜下血腫と右滑車神経麻痺を指摘され，発症2カ月後精査加療のため当科紹介となった。MRIで両側慢性硬膜下血腫のほかには脳幹部を含め虚血性変化はなかったが，後頭蓋窩の緊満化および小脳扁桃の下方偏位を認め，特発性低髄液圧症候群（SIH）を疑った。発症3カ月後，CTで慢性硬膜下血腫の急性増悪を認め，穿頭血腫ドレナージ術を施行した。術直後より複視の改善も認めた。

　Spontaneous intracranial hypotension（SIH）is a rare disease which is associated with variety of symptoms and signs including cranial neuropathies. Though diplopia occured reportedly in about one fourth of SIH cases, trochlear nerve palsy has been reported only one case in the literature.

　A 71-year-old previously healthy male developed postural headache and nausea. After 15 days, he began to have diplopia caused by right trochlear nerve palsy. He consulted our hospital 2 months later because only diplopia was not recoverd. Magnetic resonance imaging（MRI）showed bilateral thin chronic subdural hematoma（CSDH）, brain sagging and downward brain stem displacement, but not ischemic change in brain stem. We suspected SIH for right trochlear nerve palsy, and he had symptomatic therapy. Two months later, he had burr hole surgery because of disturbance of consciousness and right hemiparesis due to progressive bilateral-CSDH. To say nothing of disturbance of consciousness and right hemiparesis, his trochlear nerve palsy was completely recovered after surgery at once. Follow-up MRI showed brain sagging and downward brain stem displacement were recovered.