[Neurotological long-term follow-up in Minamata disease in Niigata, Japan].
To determine the long-term influence of organic mercurial intoxication on audiological and equilibrium findings, we followed up 36 patients neurotologically during 1980-1987 and 1991-2000 at Kido Hospital in Niigata. Typical findings were as follows: 1. In pure-tone audiometry, 24 of 72 ears (33%) showed slight hearing deterioration and 3 (4%) showed improvement. 2. Spontaneous nystagmus had disappeared in 5 patients (14%), but appeared in new 13 patients (36%). Positional nystagmus did not improve in any patient, and deteriorated in 11 (31%). 3. In optokinetic nystagmus (OKN) tests, especially in vertical OKN test showing significant deterioration (44%). 4. The caloric nystagmus test showed marked deterioration (47%). Body-equilibrium testing showed slight deterioration in 11 patients (31%) and improvement in 5 (14%). Neurotological findings thus varied widely among patients and we were concluded that these differences were caused both by duration of methyl mercury contamination and by aging factors in patients.
Mizukoshi
Kanemasa
K
Health Services Facility for the Aged Amenity Nobukiyo, Toyama.
Watanabe
Yukio
Y
Shojaku
Hideo
H
Aso
Shin
S
Asai
Masatsugu
M
Inukai
Kenya
K
Takahashi
Sugata
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D001301:Audiometry, Pure-Tone; D005260:Female; D005500:Follow-Up Studies; D006309:Hearing; D006801:Humans; D007564:Japan; D008297:Male; D020262:Mercury Poisoning, Nervous System / Q000503:physiopathology*; D008875:Middle Aged; D017120:Nystagmus, Optokinetic; D009760:Nystagmus, Physiologic; D004856:Postural Balance; D013997:Time Factors