Movement disorders are neurological conditions that prevent patients from controlling their muscles and, therefore, their movements. Some patients experience facial tics or trembling hands while others will uncontrollably flail one or more limbs. Conversely, some patients with movement disorders are unable to move a limb despite their intentions.

Most movement disorders involve the voluntary muscles, which a person controls through conscious thought. Conscious movement requires complex processes involving neurons (nerve cells) in several parts of the brain, spinal cord and muscles. A movement disorder may occur if the communication between any of these parts is slowed, disrupted or blocked. This can result from a number of causes, including physical injuries (e.g., head injury, spinal cord injury, stroke), genetic mutations and infections.

There are dozens of types of movement disorders. Some of the most common are Parkinson’s disease and essential tremor. Both cause uncontrollable shaking, but Parkinson’s disease is also associated with severe complications. Patients may also have one of the many tic disorders (e.g., Tourette syndrome), which cause uncontrollable muscle and vocal spasms. Other examples of movement disorders include Bell’s palsy, Huntington’s disease and locked-in syndrome.

Several, somewhat distinct, types of movements help characterize most movement disorders. Exaggerated or uncontrollable movements are termed hyperkinetic. They may be rapid (e.g., tics, hemiballismus) or slow and rhythmic (e.g., athetosis, dystonia). Other movements are hypokinetic, which are delayed or absent (e.g., paralysis, ataxia).  

The diagnosis of a movement disorder can be complex. This is because the nervous system is a complicated and multifaceted system that is not completely understood. Diagnosis will likely require eliminating other possible disorders that could cause similar signs and symptoms. Because diagnosis is often complicated, the process may require visiting several specialists in neurological and muscular diseases, in addition to the patient’s primary care physician.

Proper diagnosis of a movement disorder is essential in order to receive adequate treatment. Some types may cause similar symptoms, but while one form responds to a certain medication, the other may not. In addition to medications, surgery may also help relieve the symptoms of some movement disorders. This may entail surgical procedures (e.g., pallidotomy, thalamotomy) that remove certain parts of the brain involved in movement. Surgery may also be necessary to implant devices that help control the nerve action of the brain or spinal cord. Rehabilitation is likely to be part of the treatment and in some cases may be the best treatment options available. Examples of rehabilitation include physical therapy and occupational therapy.