Health Library

Opsoclonus Myoclonus Ataxia Syndrome (OMAS)

The body’s immune system protects it from foreign objects. With an autoimmune disorder, the immune system doesn’t recognize its own healthy tissue and attacks it.

OMAS is not present at birth. It develops as the immune system matures. It often starts to show during early childhood years, with most patients developing symptoms around 2 years old.

Treatment of OMAS is designed to calm down the immune system. It is important to maintain the best possible health, function and movement. Typically, children who have OMAS have a good recovery, and it’s rare that it will happen again, but it sometimes can. Some patients have lasting cognitive problems, such as inattention or difficulty with school. A child may not get back certain movements or functions.

What Causes OMAS?

There are several causes of OMAS. Around half of patients with OMAS have a tumor (commonly a neuroblastoma). Other causes are infection (such as strep, monovirus, COVID-19) or metabolic disorders. Sometimes there is no known cause for OMAS, and it is called idiopathic OMAS.

What are the Symptoms of OMAS in Children?

Symptoms can be different from child to child. Not all children will have all of the symptoms listed.

Common symptoms for OMAS in children include:

• Opsoclonus (rapid, involuntary eye movements)
• Myoclonus (brief, involuntary muscle jerk or twitch)
• Ataxia (imbalance)
• Clumsy or jerky movements
• Tremor
• Irritability
• Sleep disturbance
• Slurred speech or decreased speech production
• Vomiting

How is OMAS Diagnosed?

A neurologist is a doctor who specializes in conditions that affect the brain and nerves. The doctor will ask about symptoms and do a neurologic exam. The doctor tests vision, hearing, sensation, strength and swallowing. Coordination, balance and reflexes also are tested.

To confirm that a child has OMAS, doctors use additional tests. The main tests are:

• Imaging
• Magnetic resonance imaging (MRI). This takes a picture of the brain or other parts of the body. It uses a large magnet and radio waves to locate and make pictures of inflamed (swollen) areas. It does not have radiation. It can also help look for tumors.
• Ultrasound. This uses sound waves to create a picture inside of the body and can help look for tumors.
• X ray. This takes a picture of the inside of the body and can help look for tumors.
• Spinal tap. The doctor will remove a sample of fluid surrounding the brain and spinal cord. The lab tests for signs of OMAS and rules out infections or other diseases.
• Blood work. This rules out other infectious and inflammatory diseases that may have similar symptoms.
• Urine (pee) tests. This helps to screen for signs of a tumor.

What are the Treatment Options for Children with OMAS?

The categories of OMAS treatment include:

• Treatment of any underlying tumor. If a tumor is found, an oncologist (a doctor who specializes in cancer treatment) will help decide what treatment is needed for the tumor.
• Treatment of active inflammation. There are three common treatments used to help reduce inflammation and the autoimmune response. Often, children will receive all three types of treatment.
• Steroids often are given to reduce inflammation from an active flare-up.
• IVIG. This is an infusion of immunoglobulins (antibodies) that helps prevent the immune system from attacking the normal tissue.
• Rituximab. This is an infusion that helps reduce the production of abnormal antibodies.
• Prevention of further relapses. Medications called immunotherapies or immunosuppressants are used to prevent future relapses. This often includes continuing steroids, IVIG and Rituximab.
• Treatment of symptoms related to OMAS. Medications used to treat symptoms vary depending on symptoms caused by OMAS. These medications may be used during active inflammation or may be needed long-term. Psychologists and psychiatrists will treat mood and cognitive symptoms. Occupational, speech and physical therapies are used to help recovery from symptoms.

Children with OMAS stay on medication to help prevent further relapses. Doctors will watch closely for new symptoms and help decide when treatment can be stopped. Repeated brain MRIs may also be recommended.

What is the Long-Term Outlook for Children with OMAS?

Many patients may only have one OMAS attack, and most children recover well with timely therapy. The risk of having another OMAS attack after the first event is around 40%. After an attack, patients often have ongoing disabilities. The most common lingering symptom is cognitive impairment, including inattention and behavioral dysregulation. Children may need psychological or psychiatric treatment to manage symptoms. With treatment and prevention of relapses, most children do not develop significant disability from OMAS.