Opsoclonus myoclonus is a syndrome in which the eyes dart involuntarily (opsoclonus or dancing eyes) and muscles throughout the body jerk or twitch involuntarily (myoclonus).
Opsoclonus Myoclonus Description
Opsoclonus myoclonus is a very rare syndrome that strikes previously normal infants, children, or adults, often occurring in conjunction with certain cancerous tumors, viral infections, or medication use. Onset can be very sudden and dramatic, with a quick progression. It is an extremely rare syndrome, affecting as few as 1 in 10,000,000 people per year.
Patients with opsoclonus myoclonus all have both opsoclonus and myoclonus. They experience involuntary, rapid darting movements of their eyes, as well as lightning-quick jerking of the muscles in their faces, eyelids, arms, legs, hands, heads, and trunk. Many individuals with opsoclonus myoclonus also experience weak and floppy muscles and a tremor. The movement disorder symptoms are incapacitating enough to completely interfere with sitting or standing when they are at their most severe. Difficulties eating, sleeping, and speaking also occur. Other common symptoms include mood changes, rage, irritability, nervousness, anxiety, severe drowsiness, confusion, and decreased awareness and responsiveness.
No one knows exactly why opsoclonus myoclonus occurs. It is suspected that the presence of a viral infection or tumor may kick off an immune system response. The immune system begins trying to produce cells that will fight the invaders, either viruses or cancer cells. However, the immune cells produced may accidentally also attack areas of the brain, producing the symptoms of opsoclonus myoclonus.
About half of all cases of opsoclonus myoclonus are associated with neuroblastoma and most of the others are suspected to be associated with a low-grade neuroblastoma that spontaneously regressed before detection. It is one of the few paraneoplastic (meaning indirectly caused by cancer') syndromes that occurs in both children and adults, although the mechanism of immune dysfunction underlying the adult syndrome is probably quite different.
OMS is not generally considered an infectious disease. OMS is not passed on genetically.
Both children and adults can develop opsoclonus myoclonus, however it is most prevalent in children under the age of two. Boys and girls are affected equally.
Because OMS is rare and occurs at an average age of 19 months (6 to 36 months), a diagnosis can be slow. Some cases have been misdiagnosed as having been caused by a virus. After a diagnosis of OMS is made, an associated neuroblastoma is discovered in half of cases, with median delay of 3 months.
Diagnosis is primarily arrived at through identification of concurrent opsoclonus and myoclonus. Laboratory testing of blood and spinal fluid may reveal the presence of certain immune cells that could be responsible for attacking parts of the nervous system, such as autoantibodies. When opsoclonus myoclonus is diagnosed, a search for a causative condition such as tumor should be undertaken.
Treatment will primarily be a handled by a neurologist. An oncologist will be involved in the evaluation for cancerous tumors that may be associated with opsoclonus myoclous. A physical therapist, occupational therapist, and speech and language therapist may help patients with opsoclonus myoclonus retain or regain as much functioning as possible.
There is no known definitive cure for OMS. However, several forms of treatment have been proven to be effective:
Note: Patients that have a cancerous tumor in addition to opsoclonus myoclonus must have the tumor treated or removed before opsoclonus myclonus treatment can begin (or begin to be effective)
The prognosis for opsoclonus myoclonus is varied. Generally, it is not considered a fatal disease. The milder the case prior to treatment, the more likely full recovery may occur. When opsoclonus myoclonus is due to a viral illness, there is a higher possibility for resolution of symptoms than when the condition results from neuroblastoma. Furthermore, although the degree of myoclonus may decrease, there are still often some residual coordination problems, difficulties with learning, behavior and/or attention, and obsessive-compulsive disorder. Children with very severe cases of opsoclonus myoclonus are likely to continue to have severe problems, and will probably never have normal intelligence or the ability to live independently.
Many children have flares of their symptoms or actual relapses of the disease when they suffer from viral illnesses, even years later. These relapses may happen without warning. The treatments for such relapses are the same as for the initial illness.
Organizations & Support Groups
OMS Life - www.omslife.org
A support website where other OMS families can connect and learn more about OMS
National Organization for Rare Disorders (NORD)
P.O. Box 1968
55 Kenosia Avenue
Danbury, CT 06813-1968
Tel: 203-744-0100 or Voice Mail 800-999-NORD (6673)