[Clinical, neuroimaging and electroencephalographic findings of encephalopathy occuring after the ingestion of "sugihiratake" (Pleurocybella porrigens), an autumn mashroom: a report of two cases].

We report a 54-year-old man (case 1) and a 79-year-old woman (case 2) who presented with encephalopathy of unknown cause. Both patients were on hemodyalysis and took an autumn mashroom, "sugihiratake" (Pleurocybella porrigens), two to three weeks prior to the onset of neurological alterations. The clinical syndrome of those patients was characterized by weakness and involuntary movements of the extremities (cases 1 and 2) or dysarthria (case 1) at the onset of the disease and subsequent intractable focal motor seizures, resulting in generalized status epilepticus or comatose state, six (case 1) or three (case 2) days after the disease onset. Epileptic seizures were gradually improved in both cases. On brain MRI of case 1, no relevant lesions were detectable at the onset day, but, 6 days after onset, T2-high intensity lesions were noted in the subcortical white matter of the insular cortex, claustrum, external capsule, putamen and globus pallidus on both sides. On brain CT scan of case 2, there were no apparent lesions at the onset day, but, 4 days after onset, low density areas were noted bilaterally in the subcortical white matter of the insular cortex. Electroencephalography of the two patients taken on a day of comatose state showed periodic synchronous discharge (PSD), which disappeared when their consciousness levels were improved. As far as we have examined, there was no findings to suggest the cause of the encephalopathy in routine laboratory examinations and various viral antibody studies of the blood and cerebrospinal fluid. The reported patients could constitute a newly recognized disease entity, "sugihiratake" encephalopathy. Our observations suggest that it can be an encephalopathy with subacute progression and affect mainly the basal ganglia. Neuroimaging study and electroencephalographic findings may help the diagnosis, although they may remain unremarkable for several days after onset of the neurological alterations.