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Functional neurologic disorder (FND).png

Functional neurologic disorder (FND) refers to a group of motor, sensory, or cognitive symptoms caused by an abnormality in how the brain functions. FND is distinct from other neurologic conditions such as epilepsy, stroke, and multiple sclerosis in that there is no overt structural damage in the brain. It's a dysfunction of the connections within the brain (the “software”) rather than the structure of the brain itself (the “hardware”).

People with FND can experience involuntary movements, nonepileptic seizures, dizziness, blindness, numbness, fatigue, and pain. Memory and concentration also may be affected. An estimated four to 12 people per 100,000 will develop FND, according to the National Institutes of Health. Risk factors include adverse life experiences, having fibromyalgia or other disorders with no identifiable causes, and physical injury. Some people with FND have experienced abuse or neglect in their lives. FND is more common in women and occurs most frequently in people between the ages of 20 and 50, although adolescents and older people also can develop it.

Symptoms can include leg and arm weakness or paralysis; nonepileptic convulsions; tremor; sudden, brief involuntary twitching or jerking of a muscle or group of muscles; tics; involuntary muscle contractions that cause slow, repetitive movements or abnormal postures; problems with walking, posture, or balance; speech or voice difficulties; persistent dizziness; and clouded thinking.

To diagnose FND and distinguish it from other neurologic conditions, doctors (generally neurologists or neuropsychiatrists) conduct physical and neurologic examinations and ask questions about the person's health and medical and family histories. To evaluate for potential co-occurring conditions and to assist in developing a treatment plan, doctors also may order imaging scans and perform focused mental health and social history screenings. Other tests, which screen for other neurologic disorders, could include electromyography (to record electrical activity in muscles) and electroencephalography (to monitor the brain's electrical activity).

If you're having seizures, doctors will look for tight eye closure at the start of an event and asynchronous limb movements to distinguish a functional seizure from an epileptic one. They also may conduct video electroencephalography to monitor what you do over a period of time (from several hours to days) while brain waves are being recorded, including during a seizure, if possible.

Medications for epilepsy, essential tremor, and Parkinson's disease aren't prescribed for functional seizures or functional movement disorders because the cause is related to abnormal connections in the brain, not structural problems. Instead, doctors encourage brain retraining through a variety of rehabilitation interventions, including physical therapy, occupational therapy, and speech and language therapy. In physical rehabilitation, people are taught how to distract themselves and incorporate other techniques that allow normal movements to reemerge.

Doctors also may recommend cognitive behavioral therapy, which teaches people how to counter unhelpful or negative thinking and respond to challenging situations in more effective ways. Talk therapy can help people explore the potential connections between their FND and their thoughts, behaviors, emotions, and life experiences.

In part because FND is both neurologic and psychiatric and because it is sometimes difficult to treat, it has been stigmatized and viewed with skepticism. As doctors are better educated about the disorder and empowered to help people with it, the hope is that the stigma will lessen.

Before you visit a neurologist, make a list of your symptoms and medications, jot down any questions, and write a chronicle of your family's health issues. Bring documents from prior consultations and test results from other clinics for the same problem, or let the doctor know how to access them. Consider asking a family member or close friend to join you and take notes.

For more information, visit the Functional Neurological Disorder Society, FND Hope, which has a list of doctors who treat the condition), and

Dr. Perez is associate professor of neurology at Harvard Medical School. He’s also director of the Functional Neurological Disorders unit and director of the FND Research Program at Massachusetts General Hospital.