Atypical parkinsonism of Japan: amyotrophic lateral sclerosis-parkinsonism-dementia complex of the Kii peninsula of Japan (Muro disease): an update.

An update of the endemic parkinsonism-dementia complex (PDC) frequently associated with amyotrophic lateral sclerosis (ALS) in the high prevalence ALS focus of the Kii peninsula of Japan is presented. The initial symptom was parkinsonian gait or hypobulia/amnesia, which was followed by akinesia, rigidity, occasional tremor, bradyphrenia, abulia and amnesia, and finally by akinetic mutism. In several years, most of the patients developed ALS symptoms such as muscle atrophy, bulbar palsy, and upper motor neuron signs. Magnetic resonance imaging and computed tomography of the brain showed marked atrophy of the temporal and frontal lobes and the cerebral blood flow reduction on single-photon emission computed tomography. Marked loss of nerve cells associated with abundant neurofibrillar tangles (NFTs) in the entire central nervous system, most predominantly in the brainstem and temporal lobe was characteristic. Concomitant ALS pathology involving the upper and lower motor neurons was common, and senile plaques were absent in most cases. NFTs consisted of twisted tubules on electron microscopy. Western blot of tau protein showed three bands consisting of six tau isoforms, similar to those of Alzheimer's disease. A family history of ALS/PDC was recorded in more than 70% of patients, but no abnormal mutation or polymorphism was found in the genes of SOD1, tau, and apolipoprotein E. Familial nature and continuing morbidity of Kii ALS/PDC suggest that genetic factors may be more likely in its pathogenesis.