August 20, 2021

A functional movement disorder affects body movement without a clear cause.

Functional movement disorders used to be called psychogenic movement disorders. They are types of functional neurological disorders. 

A functional movement disorder may cause shaking, twitching, tremors, clenching, slow movement, weak feeling or stiffness. The symptoms may start suddenly. It will feel like you can’t control the symptoms. They may get worse when you pay attention to them. And they may decrease when you are distracted from them. 

There are different types of functional movement disorders. They include:

  • Functional tremor, which causes shaking in certain body parts
  • Functional dystonia, which causes muscle contractions and severe bending of joints
  • Functional gait, which causes problems with the way you walk
  • Functional myoclonus, which causes quick muscle jerks
  • Functional Parkinsonism, which causes shaking and stiffness

What causes functional movement disorders?

Researchers don’t know yet what causes them. Tests don’t show clear physical causes, such as nerve damage. The problem may be because of changes in how the brain processes signals after different kinds of stress. Signals from the brain sent to muscles may be disordered. A functional movement disorder may occur within a few months after a stressful illness or injury. People who have had a history of severe stress from sexual abuse, bullying, anxiety or depression may be more at risk. 

“I often tell patients that functional movement disorders are a software issue in the brain, versus a hardware or structure issue that is seen in other movement disorder conditions,” said Amy E. Brown, M.D., with the Movement Disorders Clinic at Vanderbilt University Medical Center. “Everything is structurally intact, but there’s a glitch in the connections.”

Symptoms of functional movement disorders

Symptoms depend on the type:

  • Functional tremor. This causes shaking movement you feel you can’t control. It may be in a hand, leg or your whole body. It may start suddenly, and only on one side of your body. Another part of your body may shake if you try to stop the shaking. But it may stop if you are distracted in certain ways. It may get worse over time. 
  • Functional dystonia. You may have muscle contractions that you feel you can’t control. This may cause your foot or arm or another part of your body to bend or twist. This may cause pain in those areas. 
  • Functional gait. This type affects the way you walk (your gait). Your gait may be slow or stiff. Or you may move your arms and body a lot when walking and not be able to control it. You may only be able to take small, careful steps. Your knees may feel weak and about to give way. 
  • Functional myoclonus. These are quick muscle contractions that feel like a sudden jerk, shake or spasm. Or a body part may feel suddenly weak for a short time. This problem may come and go over time. 
  • Functional Parkinsonism. This type causes symptoms similar to Parkinson’s disease. These include tremors and muscle stiffness at rest, and slowness when moving. But the symptoms decrease with distraction, unlike Parkinson’s disease. 

Treatment for functional movement disorders

Functional movement disorder is a complex condition. Researchers are still learning about them. There is no one treatment that works for everyone, but symptoms can be reversible. Your treatment depends on the type you have. You may be referred to a movement disorders clinic. Treatments that can help include: 

  • Physical therapy
  • Occupational therapy
  • Cognitive behavior therapy
  • Psychotherapy
  • Medicine to help with anxiety, depression or other mood disorders
  • Stress management methods
  • Transcranial magnetic stimulation 
  • Exercise
  • Hypnosis

“There is an urgency in proper diagnosis, as the best outcomes for patients tend to be quickly identifying the functional disorder, being confident in the diagnosis and seeking treatment,” Brown said. “This can be a lifelong condition though, that waxes and wanes during periods of time.”

Living with a functional movement disorder

A functional movement disorder can cause a lot of distress and can be disabling. The symptoms can cause pain and problems with daily life. They may be hard to treat. In some cases, they may get worse over time. Ask your health care provider about support groups in your area. 

Middle aged couple in soft focus sitting next to each other looking away in the distance.

The Movement Disorders Clinic at Vanderbilt University Medical Center provides comprehensive care to people experiencing involuntary and excess movement; problems with balance and coordination; muscle rigidity; slow movement; or other symptoms. We specialize in treating Parkinson’s disease, dystonia, tremors and spasticity resulting from stroke, multiple sclerosis and head injuries. Schedule your appointment online or call 615-678-0480.

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