頭部外傷後症例にみた輻輳眼振

Mixed Convergence-retraction Nystagmus: Transient Presence in the Head Trauma

I．はじめに

　輻輳眼振は中脳障害にさいしてみられ，その障害局在部位は脳脚部，動眼神経核，Perlia核，四丘体，Sylvius管周囲灰白質，基底核（Vazquez Barriere）^1），脳脚，四丘体，中脳水道周辺（Furtado）^2），Perlia核，上丘，大脳脚，橋網様体（Segarra and Ojeman）^3）といわれている。頭部外傷後にみられた幅輳眼振症例を小池ら^4），吉本ら^5）および当教室の野口ら^6）が報告しているが，その報告例は少なくかつその経過を詳細に記載した報告はほとんどみられない。われわれは頭部外傷後の一時期激しいめまい感とともに著明な輳輻眼振が出現した症例を経験した。自験例の神経耳科学的所見を述べ，若干の文献的考察を加えて報告した。

　Mixed convergence-retraction nystagmus was observed transiently in a 81-year-old man with head trauma due to traffic accident. This patient was referred to our clinic for further otoneurological examination, because of the disequilibrium after head trauma.

　The characteristic finding was the presence of mixed convergence-retraction nystagmus in the course of the post-traumatic management. However, as his complaint of vertigo was subsided favorably, the mixed convergence-retraction nystagmus was subsided. We speculated that some minimum and reversible lesion in the upper midbrain, especially around Perlia's nucleus, could manifest this transient mixed convergence-retraction nystagmus. We also emphasized the necessity to include the convergence test for a close follow-up observation on the mixed convergence-retraction nystagmus as well as spontaneous nystagmus and head-positioning nystagmus.