Stiff-person syndrome is an autoimmune disorder of the nervous system, often resulting in progressive, severe muscle stiffness and spasms of the lower extremities and back. It also can affect other body regions.

"This neurological disorder can affect anyone at any age," says Dr. Andrew McKeon, a Mayo Clinic neurologist and expert in autoimmune neurology and movement disorders. "More commonly, it affects women, usually starting in the 40s or 50s. More than 50% of patients have a coexisting non-neurological autoimmune disease, such as Type 1 diabetes or autoimmune thyroid disease."

Symptoms may include:

• Stiffness
• Spasms
• Exaggerated startle responses sometimes resulting in falls

Dr. McKeon says it is a rare, often misdiagnosed disorder.

"Stiff-person syndrome can be underdiagnosed and be mistaken as generic back pain or a psychiatric diagnosis, or overdiagnosed," says Dr. McKeon.

He says patients with fibromyalgia or other primary pain disorders, spinal cord diseases or variants of amyotrophic lateral sclerosis (ALS) are sometimes initially diagnosed with stiff-person syndrome.

Patients may need to have testing for autoimmune movement disorders. A movement disorder may be caused by the body's immune system, which is meant to fight off infection, suddenly attacking the brain. Once diagnosed, an autoimmune movement disorder can often be treated.

It's important to work with your health care team to get tested and properly diagnosed for the disorder.

Testing for stiff-person syndrome is done only at Mayo Clinic Laboratories.

"Electrophysiology testing and antibody testing in serum or cerebrospinal fluid assist in making the correct diagnosis," says Dr. McKeon.

Mayo Clinic Laboratories, based in Rochester, Minnesota, offers the only commercially available test designed specifically to evaluate all relevant biomarkers for stiff-person spectrum disorders.

Patients with relevant symptoms for the disorder may be tested with the Stiff-Person Spectrum Disorders Evaluation or the Glycine Receptor stand-alone test, which is another biomarker often found in patients with stiff-person spectrum disorders. Additionally, health care professionals may use the Movement Disorder evaluation to evaluate additional biomarkers for patients with other immune-mediated movement disorders.

Related posts:

• Sharing Mayo Clinic: Diagnosed with stiff-person syndrome
• Sharing Mayo Clinic: Finding joy after rare neurologic diagnosis.

Connect with others talking about stiff-person syndrome on Mayo Clinic Connect.

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