Reversible paraneoplastic encephalomyelitis associated with a benign ovarian teratoma

Background: Paraneoplastic encephalomyelitis (PEM) is a well characterized, and typically irreversible, paraneoplastic syndrome, usually associated wi th small cell lung cancer or other malignancy. We describe a case of a youn g woman with a benign ovarian teratoma who presented with a reversible PEM. Case report: A 24-year-old woman presented with a three week history of me mory impairment, unusual behavior, personality changes, auditory hallucinat ions, hypersomnolence and binocular diplopia. On admission she was disorien ted and inattentive with impaired short term memory. Small doses of lorazep am (1 mg), given for episodic agitation, repeatedly induced multidirectiona l bilateral nystagmus and a skew deviation, but her neurological examinatio n was otherwise normal. A left-sided pelvic mars was palpable. Brain MRI pr e- and post-gadolinium was normal. There was a mild CSF pleocytosis and an EEG showed minimal bilateral background activity irregularities. There were no other laboratory abnormalities. Two weeks after admission, she clinical ly deteriorated developing central respiratory failure and a flaccid parapl egia. Repeat MRI showed an area of increased T2 weighted signal in the medu lla and three similar areas in the spinal cord. Following removal of her tu mor, treatment with high dose corticosteroids and intravenous immunoglobuli n, she ultimately made a full recovery. Pathology revealed the tumor to be a benign ovarian cystic teratoma. Conclusions: This is the first report of a reversible PEM seen in association with a benign tumor, in this case a ma ture ovarian teratoma. Presumably an immune response directed against neura l elements of the teratoma crossreacted with normal brain, brainstem and sp inal cord antigens to cause neurologic symptoms. Tumor removal was followed by neurologic recovery.