Opsoclonus myoclonus syndrome (NORD)

Definitions & Key takeaways

Opsoclonus-myoclonus syndrome (OMS) is a rare condition, characterized by rapid, uncontrolled eye movements (opsoclonus) and sudden twitching or jerking of muscles (myoclonus). It can also present with ataxia, which often results in the inability to walk, sit or crawl, and the loss of previously attained abilities, like speech.

The cause of OMS is not well understood, but it is thought to be due to an autoimmune condition in which the body attacks the nervous system, resulting in characteristic signs and symptoms. Treatment involves immunosuppressive therapy like corticosteroids, intravenous immunoglobulin or IVIG, drugs like cyclophosphamide, and rituximab.

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Opsoclonus-myoclonus syndrome is also called OMS or dancing eyes-dancing feet syndrome. Opsoclonus describes seemingly random, involuntary, and rapid eye movements in the horizontal, vertical, and diagonal directions.
Myoclonus describes lightening-like limb movements or limb jerks, that can also be more tremulous. The syndrome also causes ataxia, which often results in the inability to walk, sit or crawl, and the loss of previously attained abilities, like speech.
Generally speaking, OMS is thought to be an autoimmune condition in which the body attacks the nervous system, resulting in the characteristic signs and symptoms.
The precise cause of OMS is unknown, but in children, it’s often due to a paraneoplastic syndrome. The idea is that a hidden or occult tumor - like a neuroblastoma or ganglioneuroblastoma - triggers the body’s immune system, and the resulting antibodies unintentionally target healthy cells of the nervous system.
CD20+ B-cells that get into the CSF fluid seem to play an important role. One brain area that gets affected is the cerebellum, which plays an important role in coordinating body movements.
In older children and adolescents OMS is thought to be triggered by an infection, and in adults, it’s often due to a paraneoplastic process due to lung or breast cancer, for example.In children with OMS, there’s almost always ataxia, so it’s sometimes referred to as OMAS - with the A representing ataxia.
In fact, most toddlers with OMS are initially misdiagnosed with acute cerebellar ataxia of childhood. The diagnosis of OMS is also often based on symptoms like opsoclonus and myoclonus which can appear abruptly, progressing over days to weeks.
Other symptoms include the loss of developmental milestones like speech, developing extreme irritability, and severe sleep disturbances.
Although there is no diagnostic test, a spinal tap can be done to look for evidence of antibodies - called oligoclonal bands - in the cerebrospinal fluid or CSF.
And lymphocyte flow cytometry can be done to look for increased amounts of CD20+ B-cells in the CSF. Finally, a CT scan, MRI scan, PET scan, or a combination of these scans can be done to help identify tumors that may have triggered OMS.
Finally, it’s important to ensure that the symptoms are not due to other processes, like brain tumors or other lesions, which can also be identified on the imaging studies.Immunosuppressive treatment options for OMS include corticosteroids, adrenocorticotropic hormone, intravenous immunoglobulin or IVIG, cyclophosphamide, and rituximab, which is a manufactured antibody that targets CD20+ B-cells, If a tumor is found, it is usually removed by surgery, and rarely requires chemotherapy.
To help treat insomnia and rage attacks, certain medications can be used. In mild cases, symptoms often improve or resolve completely, whereas in severe cases, there may be residual symptoms for life and relapses are common.##SummaryAll right, as a quick recap...Opsoclonus-myoclonus syndrome is a rare condition, with prominent ataxia and behavioral changes, known for the unique eye movement, opsoclonus, which is conjugate, involuntary, and rapid movements of the eyes in every direction, and quick, “shock-like” movements of the arms and legs, called myoclonus.
The cause is thought to be either paraneoplastic or parainfectious in most cases. The diagnosis typically involves imaging to aid with the diagnosis, while treatment includes immunosuppressive therapy