A fetal type of Minamata disease. An autopsy case report with special reference to the nervous system

Abstract

Our knowledge concerning the pathology of fetal cases of human Minamata disease (methylmercury poisoning) is relatively limited. We report here a case with description of the distribution of mercury in the systemic organs, and the ultrastructural changes of the nervous system after a survival of 29 yr. The patient was a female born in 1957, with a body wt of 3000 g, who died in 1987. She carried a diagnosis of cerebral palsy, and had a convulsion at age 3 yr. Mercury levels in her mother's hair were 101 micrograms/g at the time of examination in 1959. At autopsy, the body measured 43 cm and weighed 23 kg. The brain weighed 920 g and showed marked cerebral atrophy, mild neuronal loss in the calcarine, postcentral and precentral cortices, cerebellar atrophy, and segmental demyelination of peripheral nerves. Mercury granules were present in the brain, kidney, and liver. Ultrastructural examination of the calcarine, post- and precentral cortices, and cerebellar cortices, showed severe atrophy of nerve cells, with a decrease in rough ER and an increase in nuclear chromatin and preservation of mitochondria. Autophagosomes were increased in number. In addition, high electron density, globular and dense bodies, measuring 0.3-1.8 microns in diameter, were found, surrounded by limited membrane, within both cerebral and cerebellar neurons. In the cellebellum, synapses were well-preserved.