Delayed Opsoclonus–Myoclonus Syndrome After Ovarian Teratoma Resection

Opsoclonus–myoclonus syndrome (OMS) is a rare syndrome characterized by opsoclonus, which is irregular, spontaneous, multivectorial saccadic eye movements, along with diffuse or focal myoclonus and sometimes ataxia. OMS is associated with paraneoplastic etiologies in 20%–40% of cases, with small-cell lung and breast cancers the most common associated primary neoplasms in adults, whereas neuroblastoma is more common in children and ovarian teratoma may occur in women younger than 30 years. Onconeural antibodies are often not identified. In existing literature, paraneoplastic OMS precedes identification of the neoplasm, and neurological recovery depends on treatment of the underlying cancer. We describe a 27-year-old woman with the delayed onset of OMS one month after resection of ovarian teratoma, likely due to immune trigger from antigen exposure at the time of resection. She was treated with intravenous methylprednisolone, immunoglobulins, and eventually rituximab with resolution of her symptoms. Identification of OMS after tumor resection and prompt immunotherapy are critical for neurologic recovery. At 30-month follow-up, this patient had not experienced recurrence of OMS.