One Test, Multiple Targets: Zeroing in on Autoimmune Movement Disorders
The symptoms are baffling and distressing: A person’s body movements suddenly speed up or slow down, resulting in problems such as uncontrollable jerking of muscles or difficulties with balance. The onset is rapid, in contrast to a slowly progressing condition such as Parkinson’s disease.
A movement disorder like this might be caused by the body’s immune system, which is meant to fight infections, suddenly attacking the brain. Fortunately, an “autoimmune movement disorder” can often be treated—once its cause is discovered.
Mayo Clinic Laboratories now offers an autoimmune movement disorders evaluation, for serum or spinal fluid, that covers 20 antibodies associated with these conditions. The evaluation is the first in the United States to include the DPPX antibody, which is a biomarker of several movement disorders.
“This is a single, comprehensive evaluation that covers a wide spectrum of autoimmune central nervous system disease states,” says Andrew McKeon, M.B., B.Ch., M.D., Co-Director of Mayo Clinic’s Neuroimmunology Laboratory. “Very often there’s an overlap in these disorders. Rather than splitting our evaluation up into very specific syndromes, we’ve kept it to one evaluation that is pertinent to diverse movement disorders.”
The test can detect antibodies relevant to:
- Hyperkinetic disorders, such as chorea and myoclonus.
- Brain stem encephalopathies, including autoimmune mimics of degenerative parkinsonism.
- Stiff person spectrum disorders.
- Progressive encephalomyelitis with rigidity and myoclonus (more commonly called “PERM”).
Autoimmune movement disorders are rare and may be misdiagnosed. Although most often seen in adults, they can occur at any age. Diagnosis has typically relied on a clinical examination and observation of the disorders’ widely varying symptoms, including stiff and slow movements associated with conditions that mimic Parkinson’s disease; writhing, dance-like movements associated with chorea; and the slurred speech and incoordination resembling intoxication that are seen in ataxia. Timely diagnosis and treatment are essential to preventing irreversible loss of function.
“The prognosis varies from one antibody to another, although patients may present with the same neurological syndrome,” Dr. McKeon says. “For example, patients with autoimmune ataxia have different antibody profiles. A patient with mGluR1 antibody usually will not have cancer and will respond to immune therapy. In contrast, those with PCA1 antibody are usually found to have ovarian or breast cancer, and the neurological symptoms usually do not respond to immune therapy. It’s important to get the evaluation done quickly so treatment can begin for optimal recovery.”
Comprehensive Testing and Follow-Up Report
Testing for an autoimmune-related movement disorders may be appropriate if a movement problem starts abruptly, worsens in a matter of days or weeks, and occurs in a person with:
- No family history of the movement disorder.
- A personal or family history of an autoimmune problem outside the brain, such as celiac disease in the digestive system.
- A high risk of cancer.
The cancer link involves the immune system’s response to tumor cells. “Sometimes a patient has a cancer, in the lung for example, that isn’t symptomatic. The immune system starts to attack the cancer but gets so revved up that it starts attacking the nervous system as well,” Dr. McKeon says. “Somebody over age 50 who has been smoking for 30 years and suddenly has a movement disorder might be a candidate for autoimmune testing.”
A comprehensive evaluation saves valuable time. “If individual tests are ordered sequentially, it might take six months to get an answer,” Dr. McKeon says.
In addition to providing detailed laboratory reports after testing, Mayo Clinic Laboratories offers the opportunity for physicians to discuss the results with an autoimmune neurologist. “We have neurologists working in the laboratory who can speak with doctors on the phone or by email about what the test result means,” Dr. McKeon says. “We also have the ability to accept a referral for evaluation directly for that patient, based on that conversation.”
Once the cause of an autoimmune movement disorder is identified, it can be targeted with immunosuppressant therapy. Dosages might be high in the first one to three years. “But very often after that, patients are able to taper off treatment,” Dr. McKeon says. “We know from clinical experience what tones down the immune system. When that happens, the attack on the nervous system often stops.”