Monday, July 17, 2006

Arsenic poisoning affects upgaze

Nakamagoe et al. Upward gaze-evoked nystagmus withorganoarsenic poisoning.

The authors report 3 patients who drank well water contaminated with very high levels of an organoarsenic compound, diphenyarsenic acid, believed to originate in emetic agents used in WWII.

Clinical presentation included articulation disorder, twitching and tremors of the hands and feet, gait disturbance and oscillopsia. The patient had upbeat nystagmus and abnormal vertical smooth pursuit movements, and impaired vertical gaze-holding. The patients also had myoclonus with long tract signs, truncal and limb ataxia. MRI showed subtle midbrain changes. Symptoms improved with removal of exposure.The authors speculate that the toxin hits the rostral interstitial nucleus of Cajal.

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