周辺視野拡大に伴い回旋複視を自覚した頭蓋咽頭腫の1症例

A case of craniopharyngioma manifesting rotatory diplopia following improved peripheral visual field

　58歳の男性で頭蓋咽頭腫摘出術後，回旋複視の訴えと眼性斜頸により気づかれた滑車神経麻痺の症例を報告した。摘出後の著明な視力の改善のみでは複視を訴えず，周辺視野の感度の拡大に伴い回旋複視を自覚した。回旋融像には水平・垂直方向の融像に対する刺激とは異なり，周辺視領域への大きなサイズの刺激が必要であると思われた。

A 58-year-old male presented with decreased visual acuity in his left eye. He showed central scotoma in the left eye and homonymous temporal hemianopsia. The visual acuity was 1.2 right and 0.2 left. Magnetic resonance imaging showed craniopharyngioma which was treated by subtotal removal. His left visual acuity improved to 1.0 with improved central and peripheral visual fields 4 weeks after surgery. He developed head tilt 7 weeks after surgery and was diagnosed as left trochlear palsy. The rotatory diplopia was apparently induced by improvement in the peripheral visual field. This case illustrates that cyclofusion is evoked by stimuli to the peripheral visual field.