Opsoclonus myoclonus syndrome (OMS), also known as opsoclonus-myoclonus-ataxia (OMA), is a rare neurological disorder of unknown cause 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. It affects 2 to 3% of children with neuroblastoma and has been reported to occur with celiac disease and diseases of neurologic and autonomic dysfunction. Signs and symptoms
Symptoms include:
opsoclonus (rapid, involuntary, multivectorial (horizontal and vertical), unpredictable, conjugate fast eye movements without intersaccadic [quick rotation of the eyes] intervals)
myoclonus (brief, involuntary twitching of a muscle or a group of muscles)
cerebellar ataxia, both truncal and appendicular
aphasia (a language disorder in which there is an impairment of speech and of comprehension of speech, caused by brain damage)
mutism (a language disorder in which a person does not speak despite evidence of speech ability in the past, often part of a larger neurological or psychiatric disorder)
lethargy
irritability or malaise
drooling
strabismus (a condition in which the eyes are not properly aligned with each other)
vomiting
sleep disturbances
emotional disturbances (including fits of rage)About half of all OMS cases occur in association with neuroblastoma (a cancer of the sympathetic nervous system usually occurring in infants and children). Disease course and clinical subtypes
In most cases, OMS starts with an acute flare-up of physical symptoms within days or weeks, but some less obvious symptoms such as irritability and malaise may begin weeks or months earlier.
Since neurologic and developmental difficulties have not been reported as a consequence of neuroblastoma or its treatment, it is thought that these are exclusively due to the immune mechanism underlying OMS.One study concludes that: "Patients with OMA and neuroblastoma have excellent survival but a high risk of neurologic sequelae. Favourable disease stage correlates with a higher risk for development of neurologic sequelae. The role of anti-neuronal antibodies in late sequelae of OMA needs further clarification".Another study states that: "Residual behavioral, language, and cognitive problems occurred in the majority". Research
The National Institute of Neurological Disorders and Stroke (NINDS) conducts and supports research on various movement disorders, including opsoclonus myoclonus. These studies are focused on finding ways to prevent, treat, and cure these disorders, as well as increasing knowledge about them. Nomenclature
OMS was first described by Marcel Kinsbourne in 1962. (The term Opsoclonus was coined by Orzechowski in 1913, but it was classically described and associated with neuroblastoma by Kinsbourne). Other names for OMS include:
Dancing Eyes-Dancing Feet syndrome
Dancing Eyes syndrome (see also Nystagmus)
Kinsbourne syndrome
Myoclonic Encephalopathy of Infants (MEI), not to be confused with Early myoclonic encephalopathy (EME)
Opsoclonic Cerebellopathy
Opsoclonus-Myoclonus-Ataxia (OMA)
Paraneoplastic Opsoclonus-Myoclonus Ataxia (POMA)

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