A pre-senile case of limbic encephalitis and cerebellar degeneration, with subacute onset of progressive dementia.

In case a pre-senile patient presented subacutely progressive dementia, secondary dementia, such as paraneoplastic neurological syndrome (PNS), hypothyroidism, confusion, early phase of primary degenerative dementia and prion diseases are to be considered. It is a case of pathologically confirmed, and clinico-pathologically assessed limbic encephalitis with cerebellar degeneration. The patient was a 63-year old male, with a well followed up medical history of gastric cancer 8 years earlier. Four weeks after he presented himself at our hospital his memory and disorientation progressively declined. A neurological examination revealed gaze nystagmus, with potential secondary dementia. However, no abnormal findings were detected from systemic radiological examination, or from chemical analyses. Two months later, after the onset of the disease, he presented additional symptoms, including seizure, gait disturbance, and insomnia. On admission, neurological examinations revealed gaze nystagmus and progression of dementia; however, his thought process was relatively preserved. No paroxysmal synchronized discharge was seen on electroencephalogram. Chest X-rays showed an inflammatory infiltration. In spite of anti-biotic medication, he died due to respiratory failure. The autopsy was limited to the brain. Histologically, limited lymphocytic infiltration into the hippocampus through the entorhinal cortex, with marked neuronal loss and gliosis was observed. Neuronophagia, microglial nodules, and perivascular lymphocytic infiltration were also seen. Additionally, most of the Purkinje cells in the cerebellum were lost, with Bergmann's gliosis and sparse lymphocytic infiltration. No tumor was observed in the brain. Pathological findings of the brain were compatible with paraneoplastic limbic encephalitis and cerebellar degeneration, though no neoplasm, clinically or pathologically, was detected in this patient. Consequently, it is suggested that when a senile patient presents sub-acute onset of progressive dementia, with a variety of neurological symptoms, paraneoplastic syndrome is to be taken into consideration, even if a tumor or an auto-antibody is not detected since the resection of the tumor is still the best therapeutic means. Otherwise immuno-suppressive and steroid therapies should be used.