Periodic limb movement disorder (PLMD), also known as nocturnal myoclonus, is a condition where leg muscles contract and jerk every 20 to 40 seconds during sleep. The movement in the leg is the extension of the big toe, while at the same time the ankle, knee and sometimes the hip are partly flexed. These movements may last less than 1 second or as long as 5 seconds.

Periodic Limb Movement Disorder Symptoms

Symptoms of PLMD include insomnia and excessive sleepiness. The movements of PLMD usually do not wake the person who actually has it, but are often noticed by their bed partner. This condition is distinct from the brief and sudden movements that occur just as people are falling asleep, which can interrupt sleep.

PLMD often accompanies restless leg syndrome (RLS). 4 out of 5 people who have RLS also report having PLMD, but only about a third of people with PLMD also have RLS.

Periodic Limb Movement Disorder Causes and Risk Factors

The causes of PLMD are not clear. Some research suggests that it may be due to abnormalities in the autonomic nervous system, which regulates the involuntary actions of the smooth muscles, heart and glands.

About 6 percent of the general population has PLMD. However, the prevalence in older adults is much higher, reaching almost 60 percent. Studies suggest that PLMD may be especially common in elderly women. There are many conditions that are associated with PLMD, including sleep apnea, spinal cord injuries, stroke, narcolepsy, and diseases that destroy nerves or the brain over time.

Periodic Limb Movement Disorder Diagnosis

To diagnose PLMD your health care provider will take your medical history and do a physical exam. A diagnosis often relies mainly on the patient's description of symptoms. Your doctor may ask you to keep a sleep diary and record all sleep-related information. A bed partner often can provide information based on observations of the patient’s sleep behavior.

You may have blood tests and other exams to rule out conditions that can cause similar symptoms. Some patients are sent to a sleep lab to have a sleep study (polysomnography).

Periodic Limb Movement Disorder Treatment

The treatment for PLMD focuses on improving sleep and eliminating possible causes. Initially, your doctor may try to achieve these goals without the use of drugs. He or she may suggest certain lifestyle changes to help you cope with the condition and ease the symptoms.

Your provider may decide to prescribe medicines to help control the symptoms of PLMD or to help you sleep.

Wake Forest Baptist Sleep Disorders Center

The Wake Forest Baptist Sleep Disorders Center is accredited by the American Academy of Sleep Medicine. Our multidisciplinary team is made up of board-certified sleep specialists from neurology, pulmonary disease and pediatrics. Our team of sleep experts performs sleep studies and multiple sleep latency tests (MSLT), and provides education, advice and assistance to patients and referring physicians regarding the latest testing and treatments available for all types of sleep disorders.