Periodic limb movement disorder

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at March 16, 2016
StartDiseasesPeriodic limb movement disorder

Periodic limb movement disorder or PLMD for short is a movement disorder that occurs during the sleep cycle. Though many think that restless legs syndrome and this condition are one in the same, the two conditions are very different. The movements caused by PLMD mimic those seen in seizures, and the disorder was first called "nocturnal myoclonus" when it was discovered in the 1950's.


Definition & Facts

Repetitive cramping or jerking of the legs, during the sleep cycle, is referred to as PLMD. The movements occur about every 20-40 seconds and are rhythmic in nature. This sleep disorder causes disrupted sleep and often causes the person to be drowsy the next day.

It occurs in conjunction with other sleep and medical disorders. The strange sensations in the legs can also be present in the arms too. There is said to be about 80 percent of people suffering from restless legs syndrome who also suffer from PLMD. This condition can occur at any age, but is more commonly found in the middle-aged and elderly population.

Symptoms & Complaints

Though PLMD causes the bodies to thrash about at night, many people are not aware they have a problem. The common symptoms that present are daytime fatigue, unproductive sleep, and falling asleep during daytime hours.

Though the person doesn't usually know that they are having sleep disturbances, it is often their partners that report something unusual. It is very difficult to sleep with someone who is constantly moving. Some people report having pain in their legs and arms from the constant movements, or muscle soreness.

The rhythmic movements commonly start in the lower extremities. They often start in the big toe, work their way to the ankle, and finally to the knee and hip area. The upper extremities are often affected as well, such as the arms and hands. The person affected may some nights that are worse than others.


There is no exact known reason for PLMD. However, it is found that many people also have other medical problems, like narcolepsy, Parkinson's disease, diabetes, and an iron deficiency that put them at an increased risk.

Whereas restless legs syndrome has been the focus of many studies, PLMD hasn't received as much attention and research. It doesn't seem to be gender specific, as either males or females can get it, whereas restless legs syndrome affects more women than men.

Diagnosis & Tests

To make a diagnosis of PLMD, an overnight test called a polysomnogram must be conducted. This test will record a person sleeping and capture any bioelectrical signals that are coming from the body during this period. The PSG will monitor respiratory activity to look for sleep disorders that cause breathing issues, like sleep apnea. During an episode of sleep apnea, the muscles in the throat often collapse, causing difficulty breathing. Apnea must be ruled out before a proper diagnosis of periodic limb movement disorder can be given.

Other forms of testing include thorough neurological examinations. The doctor will want to make sure there are no other movement disorders to blame. Huntington's disease as well as Parkinson's disease cause jerking and involuntary movements both during sleep and awake times. Ruling out these other conditions is essential.

There are numerous blood tests that can also prove to be valuable. Low levels of iron, vitamin B12, folic acid and magnesium can cause similar symptoms in the body. Additionally, the thyroid can cause problems related to PLMD and needs to be evaluated too. Armed with the results of these tests and the patient's or partner's description of the problem, a proper diagnosis can be made.

Treatment & Therapy

To treat PLMD, doctors look to the same medications that are used in Parkinson's treatments. The medical community has also had some luck treating it with narcotics, anti-convulsing medications, and benzodiazepines. Due to the fact that there is no cure, the medications will need to be taken indefinitely to see some relief.

Some medications seem to make the conditions worse. Those who are on antidepressants medications such as tricyclic antidepressants, find that their conditions worsen. Both stress and sleep deprivation seems to also exacerbate the situation. Caffeine and alcohol are also key elements in worsening the symptoms of PLMD.

Dopaminergic agents have proven somewhat effective in treating both restless legs syndrome and also PLMD. They have proved successful in treating both leg jerks and the arousals. The goal is to reduce the number of leg kicks and the number of arousals per hour of sleep, which results in a more relaxed sleep. Some medications simply shift the leg movements from the night to the day. There is much trial and error, and treatment involves finding what medication or combination of medications works.

Prevention & Prophylaxis

Because of the fact that there is no known cause of periodic limb movement disorder, there is no way to instruct people on how to avoid it. Those who think they have this condition should be checked to ensure there is not an underlying condition at the root of their issues.

It's important to get at least 6-8 hours of rest. Also important is to avoiding drinking and eating things with caffeine in them, such as chocolate, soda, and energy drinks.