A 50-year-old woman developed gait disturbance and
hypersomnia over a period of a month. General physical examination revealed axillary lymph node swelling. On neurological examinations she was fully orientated but hypersomnic; short term memory disturbance, horizontal gaze evoked nystagmus and ataxic gait were observed. Electroencephalography disclosed a tendency for easily decreasing vigilance with delta activities but normal dominant rhythm. Cerebrospinal fluid examinations showed increased
protein amounts (109 mg/dl) without either
pleocytosis or atypical cells. An echogram of the breasts revealed a tiny mass in the left side. Pathological studies on a biopsied lymph node and the mass in her left breast showed a mammillary duct
carcinoma. Brain MRI was normal, and no anti-neuronal antibody was detected in sera by two dimensional immunoblotting using human brain crude
antigens. She was diagnosed as having
paraneoplastic limbic encephalitis (PLE) associated with
breast cancer. Over 42 hours polysomnography showed long total sleep time (TST) with a high ratio of sleep stage 1/TST and no REM sleep abnormalities; this resembled a thalamic-hypothalamic damaged sleep pattern. At first she was treated with
plasma exchanges, but no improvement was observed. Hormonal and
chemotherapies produced partial resolution of her
neurologic symptoms and there were signs of reduction of the breast mass. Most reported PLE cases with
hypersomnia have been associated with
testicular cancer and
anti-Ma antibodies. The present case is an extremely rare example manifesting
hypersomnia without either
testicular cancer or
anti-Ma antibody. Since anti-
tumor therapy successfully ameliorated her
neurologic symptoms, cell-mediated immunity against a common
tumor and neuronal
antigens rather than hormonal immunity may have played a role in the development of her PLE.