Recognizing Opsoclonus Myoclonus Syndrome

The rare neurological disorder opsoclonus myoclonus syndrome (OMS) affects fewer than 1 person in 10 million annually, but it is more common in children with neuroblastoma and in some adults with breast or small-cell lung carcinoma. OMS is characterized in part by rapid abnormal eye movements.

It is thought to be an immune-mediated injury to either pontine omnipause cells which inhibit gaze center burst neurons or cerebellar hemispheres which disinhibit the factorial nucleus . Since physicians are unlikely to see many OMS patients, a team of researchers from Boston, MA, set out to offer clinical features, diagnostic findings and recommended treatments.

In an abstract presented Sunday April 19 at the American Academy of Neurology 2015 annual meeting in Washington, DC, Pooja Raibagkarm, MD, and colleagues at Massachusetts General Hospital report on 6 adults with OMS ages 24 to 62, half of them women.

They looked at clinical laboratory and imaging findings.

They found that ocular flutter and ataxia were present in all patients, but opsoclonus was found in only 2 patients. Myoclonus was found in 4 patients and encephalopathy was present in 2 patients.

Three patients had neoplasms, 1 was a benign ovarian dermoid tumor but the others were a uterine carcinosarcoma and a neuroblastoma.

One of the cancer patients died. But the 3 patients who did not have cancer improved with intravenous corticosteroids until intravenous immunoglobulin was administered.

Among their findings, the team said, were that ocular flutter and ataxia are the key clinical features in diagnosis OMS and that patients without malignancies may achieve complete remission with intravenous immunoglobulin.