Invited. MR findings of Minamata disease — Organic mercury poisoning

Abstract

We describe MR findings in patients with Minamata disease who have been followed for a long time. All patients examined were affected after daily eating of a large quantity of methylmercury-contaminated seafood, from 1955 to 1958, and showed typical neurological findings. On MR images, the visual cortex, the cerebellar vermis and hemispheres, and the postcentral cortex are significantly atrophic in Minamata disease. The visual cortex is slightly hypointense on T1-weighted images and hyperintense on T2-weighted images, probably representing the pathologic changes of status spongiosus. MRI can demonstrate the lesions located in the calcarine area, cerebellum, and postcentral gyri, which are probably related to three of the characteristic manifestations of this disease: the constriction of the visual fields, ataxia, and sensory disturbance, respectively.

Contribution of metals to brain MR signal intensity: review articles

“…Organic mercury poisoning causes central nerve and peripheral nerve toxicity. In the chronic phase of organic mercury poisoning, atrophy of the calcarine area, cerebellum, and postcentral gyri is observed [125,126]. However, no specific signal intensity due to histologically proven mercury deposition has been reported.…”

Preliminary Findings on the Effects of Occupational Exposure to Mercury Vapor Below Safety Levels on Visual and Neuropsychological Functions

“…[31][32][33][34] Visual field constriction has been correlated with significant impairments in the calcarine cortex shown by magnetic resonance imaging. 35,36 In the early 1970s in Iraq, as a result of poisoning of farmers by consumption of grain treated with methylmercury as fungicide, the visual field changes in most of the patients were also described as concentric constriction. 37 Visual field losses have also been found to result from exposure to Hg vapor.…”

“…35,36 Even at low levels of exposure to methylmercury, the calcarine area had changes in its glial cells in monkeys. 38,39 In the case of Hg vapor, magnetic resonance imaging showed a mild central and cortical atrophy in frontal regions and in the subcortical white matter in a subject exposed to Hg vapor in a thermometer factory, and this was related to the difficulties in neuropsychological tests.…”

In Vitro Models for Methylmercury Neurotoxicity: Effects on Glutamatergic Cerebellar Granule Neurons

“…All these effects correlate with the loss of neurons from several areas of the brain, among them the CGC layer (Korogi et al 1998 ;Ekino et al 2007 ;Eto et al 2010 ) . In addition to cerebellar neurodegeneration, abnormal migration of neurons in the cerebellum and microtubule formation defi cits were observed during fetal neural development and in affected newborn babies (Choi et al 1978 ;Castoldi et al 2000 ) .…”