About Paraneoplastic Neurological Disorders (PND) > Central Nervous System (Brain and Spinal Cord) > Paraneoplastic Opsoclonus-myoclonus or Opsoclonus-ataxia

Paraneoplastic Opsoclonus-myoclonus or Opsoclonus-ataxia

Opsoclonus is a neurologic disorder in which the patient’s eyes rapidly move from one direction to another in an uncontrolled way.

Myoclonus refers to uncontrolled muscle twitching that can affect the face, arms or legs.

Opsoclonus and myoclonus frequently occur together as symptoms of several different diseases. Opsoclonus and myoclonus are not diseases by themselves but are the signs of several diseases (with or without cancer association).

Opsoclonus and myoclonus frequently occur along with ataxia (difficulty controlling the muscles of the trunk- keeping a steady posture while sitting or standing, or difficulty controlling muscles of the arms and legs). In the arms and hands the movements are no longer smooth. When reaching ones arm out toward an object, it weaves back and forth making it difficult to reach the object. The legs don’t go where the patient wants them to, making walking almost impossible and giving the appearance of being intoxicated.

Paraneoplastic opsoclonus (with or without myoclonus or ataxia) can affect children or adults. In each case the clinical picture and associated tumors are different:

  • Paraneoplastic opsoclonus in children: This is the most common paraneoplastic syndrome in children. It usually affects patients younger than 4 years, and starts with sudden development of staggering and falling. These symptoms are usually followed by:
    • body jerks
    • drooling
    • refusal to walk or sit
    • ataxia
    • opsoclonus
    • irritability
    • sleep disturbances

The associated tumor is called neuroblastoma. Although symptoms may resolve or improve after treating the tumor and with immunotherapy, most children are left with behavioral problems, language and psychomotor deficits, problems in sleep and sometimes episodes of rage.

There is a large amount of evidence that paraneoplastic opsoclonus and myoclonus in children is mediated by the immune system and that antibodies are probably involved. However, no specific antibody has been identified so far. Therefore there is no “antibody test” that can be used as a marker of this disorder.

In addition to treating the tumor other treatments may include corticosteroids, ACTH, plasma exchange, intravenous immunoglobulins (IVIg), or rituximab.

  • Paraneoplastic opsoclonus-myoclonus in adults: As in children, this disorder includes uncontrolled eye movements and muscle jerkiness, but adults usually have fewer behavioral abnormalities, less irritability and sleep problems. They do however have more truncal and gait ataxia. In contrast to the ataxia associated with “paraneoplastic cerebellar degeneration” which is severe in the arms, legs, trunk, and gait, the ataxia of patients with opsoclonus and myoclonus mostly affects the trunk and gait. The cancers more frequently associated with this disorder are located in the lung, breast and ovary.

As in children, there is evidence that this disorder is helped by the immune system. For example, many of these patients have antibodies that react with the cell surface of neurons (however, the specific protein targeted by the antibodies has not been identified). Sometimes, well-known paraneoplastic antibodies are identified, but this only occurs in approximately 20% of the patients. The best known antibody is called anti-Ri. Patients with this antibody are usually women with breast cancer or gynecological tumors. However, the anti-Ri antibody has also been identified in both women and men with other tumors.

Treatment of the tumor and immunotherapy usually results in improvement or stabilization of the neurologic symptoms. If the tumor is not treated, the neurologic symptoms usually progress despite immunotherapy.

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