後迷路性障害例における温度検査所見—両側異常（反応低下あるいは廃絶）の診断的意義

DIAGNOSTIC SIGNIFICANCE OF BILATERAL CALORIC ABNORMALITIES IN RETROCOCHLEAR LESIONS

　I．はじめに

　最近，感音難聴や平衡障害を伴う神経疾患の診断に神経耳科学の果たす役割は重要なものとなつている。このためこれら神経疾患の検討に際して，まずわれわれが求められることは難聴，平衡障害が末梢性か中枢性のいずれであるかということであろう。このことは現在の診断法をもつてすれば一見容易なようであるが実際に検討される個個の症例については必ずしもそうではないようである。その理由の一つは現在の診断法をもつてしても，前庭神経核，あるいは蝸牛神経核以下の障害とそれ以上の障害とがしばしば明確に鑑別され得ず，後迷路性障害，あるいは脳幹障害として漠然とされるためであると考えられる。聴力障害に関しても脳幹部障害と神経幹の障害とを鑑別することはしばしば困難を伴うが平衡障害に関してはより難しいと考えられる。

　歩行障害を主訴とし脳神経症状を有する症例の中にしばしばこのような点で神経科医との討論を必要とした症例が多く，これらの例の多くが温度検査で両側の高度反応低下あるいは廃絶を示したので，この所見の診断的意義について若干の検討を加えた。

　The findings of caloric test in 17 cases in which either reduced or no response were found bilaterally were analysed. These cases presented no previous history of labyrinthine or vestibular nerve lesions such as Ménière's disease, strepto mycin or kanamycin intoxication, head and neck trauma, whiplash or common cold.

　Ten cases out of 17 were accompanied with neurological signs and symptoms and 7 cases were not.

　In 8 cases with neurological disorders it was foud that they were frequently accompanied by gait disturbances, abnormalities in body righting reflex, oculomotor disturbances, direction-changing nystagmus and retrocochlear deafness, the aggregate of which suggested lesions in the lower part of pons in the brain stem. In 2 other cases the lesion was thought to be localized in the vestibular nerve probably due to viral infection or tumor invasion without involveing the brain stem.

　Various other factors effecting caloric response such as alertness, optic fixation, psychic disorders and drug influence should be ruled out before some lesions in bilateral peripheral or central vestibular system could be considered.

　Three cases out of the 7 that showed no neurological signs and symptoms were thought to be vascular disturbances in the brain.

　In 225 cases with vertigo in another series of patients in which neither hearing impairement nor neurological signs including nystagmus were found, 14 cases showed caloric abnormalities; 2 of these cases were effected with bilateral abnormality with unknown etiology.