Toxic leukoencephalopathy due to yam bean seeds poisoning

Toxic leukoencephalopathy is attributed to exposure to a wide variety of agents, including systemic chemotherapy, cranial irradiation, illicit drug abuse, and toxins from the environment. Diagnosis of this disease requires documented exposure to a toxin, neurobehavioral deficits, and typical neuroimaging abnormalities. Intoxication by compounds extracted from yam bean seeds may mimic cyanide poisoning but fail to respond to antidotal therapy. We report a 54-year-old Chinese woman who developed disturbed consciousness after eating 40 pieces of yam bean seeds. Head computed tomography obtained 24 hours after the episode was normal. However, magnetic resonance imaging obtained 20 days after the episode revealed symmetrical faint high signal over the bilateral periventricular white matter on T1-weighted image, which turned into diffuse and symmetrical bright high signal on FLAIR. The diagnosis of this patient was toxic leukoencephalopathy by yam bean seeds intoxication. The changes in brain images after yam bean seeds intoxication have not ever been reported. Physicians in Asia and the Pacific islands should have a high index of suspicion when they care for patients with acute confusion and a high anion gap metabolic acidosis but normal serum cyanide level.