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At a glance

Rare neurologic disorder usually affecting infants and young children. It is characterized by the presence of opsoclonus, myoclonus, ataxia, and behavioral abnormalities such as sleep disturbances, irritability, developmental delays, decreased social interaction, lethargy, mutism, and visual disturbances. Other features include sudden onset of brief, repeated, shock-like spasms of several muscles within the arms, legs, or the entire body. Impaired ability to control voluntary movements is present. Jerking movements of the eyes are most often present. In 50% of patients, a malignant tumor (neuroblastoma) is responsible for the symptoms associated with this syndrome. A viral infection may also be responsible.

Synonyms

Ataxia-Opsoclonus-Myoclonus Syndrome; Dancing Eyes Syndrome; Dancing Eyes-Dancing Feet Syndrome; MEI Syndrome; Myoclonic Encephalopathy of Infants Syndrome; Infancy Myoclonic Encephalopathy Syndrome; Neuroblastoma Paraneoplastic Syndrome; Opsoclonic Encephalopathy; Opsoclonus-Myoclonus Syndrome; OMA Syndrome; Opsoclonus Myoclonus Ataxia Syndrome; Opsoclonic Encephalopathy.

History

The Opsoclonus-Myoclonus Syndrome (OMS) was first described by M. Kinsbourne in 1963 as an extremely rare paraneoplastic syndrome associated with neuroblastic tumors.

Incidence

The incidence is estimated at 0.03 to 0.18 cases per million in the general population. About 2 to 4% of patients affected with neuroblastoma will develop Kinsbourne Syndrome, and in about half of the patient with OMS will present with an underlying neuroblastoma.

Genetic inheritance

None. Sometimes chromosome 1 deletions are found in the associated neuroblastoma tissue.

Pathophysiology

Autoimmune disease initiated by a viral infection or a neuroblastoma and attacking the cerebellum (similarity of antigens).

Diagnosis

Mainly clinical. Brain histology reveals widely distributed perivascular lymphocyte infiltration in the brain.

Clinical aspects

Kinsbourne Syndrome occurs either spontaneously, in association with a neuroblastoma, or following an infectious process. Approximately 50% of cases are linked to an occult neuroblastoma, but the clinical features and the response to therapy are comparable with or without neuroblastoma. However, neuroblastoma associated with Kinsbourne Syndrome has a better prognosis than without it. Several investigations point toward an immunologic process. Children usually present with an encephalopathy with progressive ataxia, uncontrolled movements of the head, myoclonic jerks, and chaotic jerking movements of the eyes. Sometimes it is associated with mental retardation. In 60% of cases, Kinsbourne Syndrome improves with steroid or adrenocorticotropic hormone (ACTH) administration. Recurrences and sequelae such as speech problems and mental deficiency are found in approximately 90% of the cases and are severe in 60%. Usually, Kinsbourne Syndrome features improve with treatment of the underlying neuroblastoma.

Precautions before anesthesia

Usually these children present for surgery of neuroblastoma or for radiotherapy. Hyperfractionated radiotherapy (twice daily) is used in some of these patients. Check for neuroblastoma location and catecholamine levels. Check for deviation or compression of the airways and great vessels, pneumonia, or pleural ...

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