眼部局所の加温によりUhthoff徴候を呈した球後視神経炎の1例

A case of retrobulbar optic neuritis with Uhthoff's sign in local eye warming.

　55歳女性の右）球後視神経炎の経過中にUhthoff徴候（以下U徴候）を呈した1例を報告した。

　U徴候は，初診時0.06の視力が1.0に回復してきた第10病日より第25病日まで約15日間発現した。入浴により右視力は0.1に低下したが，入浴中眼部を冷却すると視力低下は0.4に抑えられた。また眼部を10分間ずつ加温，冷却したところ，体温はほぼ一定で，結膜嚢温のみの上昇，下降により右視力は1.0→0.5→0.8,CFFは30→25→30Hzとなり，U徴候，逆U徴候を認めた。

　以上より，U徴候は，体温上昇が必須条件ではなく，眼部局所の温度変化に深く関係していることが示唆された。

We reported a 55-year-old female of retrobulbar optic neuritis in the right eye with Uhthoff's sign (U-sign). At the first examination the visual acuity in the right eye was 0.06, which recoverd to 1.0 after systemic steroid administration for 10 days. U-sign started on the 10 th day of the treatment and continued till 25th day.

Her visual acuity in the right eye decreased from 1.0 to 0.1 when her body temperature increased while in a hot bath. But the cooling of her eyes while in a hot bath suppressed visual decrease from 0.1 to 0.4. Her eyes warmed for ten minutes and then cooled for ten minutes alternately, the visual acuity changed 1.0→0.5→0.8, and the central flicker frequency changed 30→25→30 Hz. In the meantime, the body temperature remained unchanged; while only her conjunctival temperature changed.

We recognized the U-sign and the reverse U-sign were accompanied by the local optic temperature change. It is suggested that the elevation of body temperature is not necessarily needed for the onset of U-sign, but that the change in local optic temper- ature is closely related with it.