[An autopsy case of encephalopathy associated with small cell carcinoma of the stomach with nonconvulsive status epilepticus resembling Creutzfeldt-Jakob disease].

A 64-year-old man developed progressive dementia and altered consciousness with myoclonus over 2 months. Neurological examination revealed mild dysphagia and negative myoclonus of both hands. Electroencephalography (EEG) showed continuous periodic synchronous discharge (PSD) of 1 Hz, although his EEG abnormality was not similar to that usually observed in Creutzfeldt-Jakob disease (CJD). Magnetic resonance imaging (MRI) of the brain revealed only few lacunes. Laboratory data were also normal. Since his consciousness level fluctuated and the PSD were spiky, we came to a diagnosis of nonconvulsive status epilepticus (NCSE). After administering the valproic acid, his symptoms and EEG finding improved. Nine months after the onset, despite his continued valproic acid, the patient had recurrent NCSE and PSD of 1 Hz. Diffusion-weighted MRI showed a T2-hyperintense lesion in the right parietal lobe, where SPECT scans showed hyperperfusion. After adding zonisamide, he improved slowly. The follow-up MRI and SPECT showed a disappearance of the previous lesion. Now CT scans of the abdomen showed enlarged periaortic lymph node and endoscopic ultrasonography disclosed a submucosal tumor of the stomach. Biopsy of the periaortic lymph node by laparotomy revealed undifferentiated adenocarcinoma with its origin being unclear. Chemotherapy didn't work well for the tumor and the patient underwent a downhill course, although his mental and neurological manifestation were mostly unremarkable. Two years and four months after the onset, he died in emaciation. Autopsy confirmed small cell carcinoma originating in the stomach and metastases in the liver and lungs. Neuropathological examination revealed only mild scattered gliosis. This case was unique in the prolonged CJD-like manifestations, which turned out to be due to NCSE. Despite anti-neuronal antibodies were not detected, we suspect yet another paraneoplastic brain syndrome in this patient.