Opsoclonus Myoclonus

Opsoclonus myoclonus (OMS) is a rare neurological disorder of unknown causes which appears to be the result of an autoimmune process involving the nervous system.

It is an extremely rare condition, affecting as few as 1 in 10,000,000 people per year. About half of all OMS cases occur in association with neuroblastoma – a cancer of the sympathetic nervous system usually occurring in infants and children. It typically occurs at an average age of 19 months (6 to 36 months).

Symptoms include:

  • An unsteady, trembling gait
  • Myoclonus – brief, shock-like muscle spasms
  • Opsoclonus – irregular, rapid eye movements
  • Difficulty speaking, poorly articulated speech, or an inability to speak
  • A decrease in muscle tone
  • Lethargy
  • Irritability
  • Malaise – a vague feeling of bodily discomfort
  • Drooling
  • Vomiting
  • Sleep disturbances
  • Strabismus – a condition in which the eyes are not properly aligned with each other

Opsoclonus myoclonus may occur in association with tumors or viral infections. It is often seen in children with tumors.

The prognosis for opsoclonus myoclonus varies depending on the symptoms and the presence and treatment of tumors. With treatment of the underlying cause of the disorder, there may be an improvement of symptoms. The symptoms sometimes recur without warning. Generally the disorder is not fatal.

Treatment for opsoclonus myoclonus may include corticosteroids or ACTH (adrenocorticotropic hormone). In cases where there is a tumor present, treatment such as chemotherapy, surgery, or radiation may be required.