ORIGINAL CONTRIBUTION Bilateral Horizontal Gaze Palsy in Presumed Paraneoplastic Brainstem Encephalitis Associated With a

Abstract: A 28-year-old woman with a previous history of recurrent benign ovarian teratoma developed a bilateral horizontal gaze palsy, a right facial paresis, and bilateral trigeminal hypesthesia. Magnetic resonance imaging dis-closed high signal in the rostral pons. Results of all other laboratory studies, including those for antineuronal anti-bodies (anti-Hu, anti-Yo, anti-Ri, anti-Tr, anti-Ma1, anti-Ma2, and anti-CV2/CRMP5), were negative. Pelvic ultra-sound revealed a residual mass in the left ovary, which was confirmed as teratoma on surgical pathological examina-tion. Complete neurologic recovery occurred within two weeks of surgical removal of the teratoma and treatment with intravenous corticosteroids and immunoglobulin. This case demonstrates that a search for an occult neoplasm is extremely important in the diagnosis of presumed paraneo-plastic encephalitis even if antineuronal antibodies are not found. (J Neuro-Ophthalmol 2004;24: 114–118) Paraneoplastic syndromes are remote effects of cancerthat are not directly related to tumor growth, metastases, metabolic or nutritional derangements, or side effects of therapy. The clinical manifestations of a paraneoplastic process are often the first presentation of an underlying tu-mor (1). Paraneoplastic encephalomyelitis–sensory neu-ronopathy (PEM-SN) is a well-characterized syndrome that is typically irreversible and most commonly associated with small-cell lung cancer and anti-Hu antibodies (2). The clinical manifestations are variable, including multifocal involvement of the central or peripheral nervous system or both, and brainstem or limbic encephalitis. There are a few case reports of supranuclear, nuclear, or internuclear ocular motor abnormalities affecting horizontal or vertical eye movements or both in patients with PEM-SN (3–8). We re-port a case of complete bilateral horizontal gaze palsy in a patient with a presumed paraneoplastic brainstem encepha-litis associated with a benign ovarian teratoma. Surgical re-moval of the tumor, combined with intravenous corticoste-roid and immunoglobulin treatment, rapidly reversed all neuro-ophthalmic manifestations