Opsoclonus-Myoclonus Syndrome

What is opsoclonus-myoclonus syndrome (OMS)?

Opsoclonus-myoclonus syndrome (OMS) is a rare autoimmune condition that usually affects young children. Most children with OMS are diagnosed at around 18 months of age. OMS affects one out of every 5 million children worldwide, and is slightly more common in girls than boys.

In OMS, a small tumor in the body (called a neuroblastoma) or a viral infection triggers the immune system to attack the nervous system. The symptoms of OMS usually begin abruptly and can include rapid, repeated eye movements (opsoclonus or “dancing eyes”), jerking movements (myoclonus), and loss of balance (ataxia). OMS may be initially diagnosed as acute cerebellar ataxia.

Most patients with OMS improve with standard immunotherapy treatment, though the relapse rate in children is 50 to 75 percent. Aggressive, early treatment appears to lower the rate of relapse and improve outcomes.

What are the symptoms of opsoclonus-myoclonus syndrome?

Opsoclonus-myoclonus syndrome symptoms include rapid, repeated eye movements (opsoclonus) and repeated, brief muscle jerks in the arms and legs (myoclonus). Other symptoms may include:

• loss of balance with inability to sit, stand, or walk (ataxia)
• hand tremors
• difficulty with speech
• sleep problems, specifically insomnia
• behavioral problems such as irritability and rage attacks
• reduced muscle tone (hypotonia)
• vomiting

In some cases, speech and language may be completely lost. Symptoms of OMS often start abruptly and can become chronic.

What causes opsoclonus-myoclonus syndrome?

The cause of opsoclonus-myoclonus syndrome can differ by age. In young children, the cause of OMS in 50 to 80 percent of cases is a small, benign (not cancerous) tumor of nerve cells called a neuroblastoma or a ganglioneuroblastoma. The tumor is usually located in the chest or abdomen and is thought to cause the immune system to attack the nervous system.

The origin of the rest of the cases is unknown (idiopathic) or may be caused by tumors that have regressed. Viral infections may also be the cause, especially in older children and teens. OMS in adults is most often caused by lung or breast cancer.

How is opsoclonus-myoclonus syndrome diagnosed?

To diagnose OMS, your doctor will review your child’s medical history and examine their nervous system. Your child may also need magnetic resonance imaging (MRI) to create two- and three-dimensional images of their brain, as well as imaging to look for a neuroblastoma.

Your doctor may test the fluid around your child’s brain and spine (cerebrospinal fluid) for signs of inflammation.

How is opsoclonus-myoclonus syndrome treated?

Your child’s doctor may recommend immunotherapy as treatment for opsoclonus-myoclonus syndrome. Immunotherapy is a type of treatment that helps keep the body’s immune system from attacking the brain. Standard immunotherapy treatment for OMS is started soon after diagnosis and usually continues for at least one to two years. The goal of treatment is a decrease or disappearance (remission) of symptoms.

A combination of immunotherapies is typically prescribed and may include a high dose of corticosteroids, intravenous immunoglobulin (IVIg), and rituximab for moderate to severe cases. Your doctor may recommend other immunotherapies for milder cases or if your child experiences a relapse.

If your child’s OMS is caused by a tumor, your doctor may recommend surgery to remove (resect) it. Tumors in young children usually do not require chemotherapy or radiation therapy. Your child may also need physical therapy, speech therapy, or occupational therapy to improve development and long-term prognosis.

How we care for opsoclonus-myoclonus syndrome

The Pediatric Neuro-Immunology Program at Boston Children’s Hospital is dedicated to the comprehensive care of children and adolescents who have autoimmune disorders of the brain and spinal cord (neuro-immune disorders). Our program works in collaboration with oncology, psychiatry, neuropsychology, and physical, occupational, and speech therapy to provide comprehensive, individualized care for each patient.