What is periodic limb movement disorder?
Periodic limb movement disorder (PLMD) involves repetitive episodes of muscle movements that usually occur in the legs. The movements are described as a jerking motion or an upward flexing of the feet. The movements happen about every 20 to 40 seconds and occur in clusters lasting from minutes to a few hours.
PLMD is considered a sleep disorder when these movements disrupt sleep and lead to daytime effects such as sleepiness. Most children and adolescents with PLMD are unaware that these movements are taking place.
Many children and adolescents with PLMD may also experience restless legs syndrome--another movement disorder in which the child or adolescent reports an uncomfortable sensation and irresistible urge to move his or her legs when awake. This urge usually happens in the evenings around bedtime but can occur at other times when the legs have been inactive, such as when sitting still for a long period of time (eg, during long car rides or while watching a movie).
What causes PLMD?
The exact cause of this disorder is not known. Scientists think PLMD may be related to a low iron level or problems with limb nerve conduction due to diabetes or kidney disease. Though not necessarily a cause, the following are all thought to "influence" or increase the risk of PLMD:
- restless legs syndrome
- side effects of some medications including antidepressants (eg, tricyclic antidepressants and SSRIs [selective serotonin reuptake inhibitors]), dopamine-receptor antagonists (eg, some anti-nausea drugs), lithium and some anticonvulsants
- other sleep disorders such as narcolepsy (a sleep disorder involving overpowering urge to sleep during waking hours) and sleep-related eating disorder
- neurodevelopmental and genetic disorders, including attention deficit hyperactivity disorder (ADHD) and William’s syndrome
- spinal cord injury/spinal cord tumor.
What are the signs and symptoms of PLMD?
Symptoms of PLMD include:
- Leg movements. Repetitive leg movements in one or both legs are the classic sign of PLMD. Remember, though, that the child or adolescent experiencing PLMD may be unaware of his or her leg movements since they occur during sleep.
- Sleep disruption/restless sleep. The frequent leg movements cause disturbed sleep and multiple awakenings. These awakenings are brief and termed "arousals." They can be easily missed by the onlooker but captured on a sleep test by EEG (brain wave) analysis.
- Daytime sleepiness, behavior and school performance problems. The sleep disruption may cause daytime drowsiness. Many times, children will not appear sleepy but rather they may manifest this as irritability, hyperactivity, and impulsivity.
How is PLMD diagnosed?
PLMD is diagnosed in an overnight sleep study (polysomnography). As your child or adolescent sleeps in the laboratory, a polysomnogram will chart his or her brain waves, heart beats, respirations, and limb movements. In addition to the polysomnogram, a complete medical history and physical exam will be conducted. Urine and blood samples could be taken to look for anemias, metabolic disorders and low iron levels that could be causing or contributing to PLMD.
How is PLMD treated?
Treatment options for PLMD can include any of the following:
- Avoid caffeine--Caffeine can make PLMD worse so avoid caffeinated products (eg, coffees, teas, colas, some non-cola pops [like Mountain Dew], energy drinks, chocolates, and some medications [Excedrin®]).
- Check iron level--Your physician may wish to check your child’s iron and folic acid levels. Low levels of these nutrients can contribute to PLMD symptoms.
- Take medications--Several different types of drugs that play a role in regulating muscle movements can be tried as a last choice. These may include dopaminergic agents (eg, carbidopa-levodopa and other newer compounds like ropinirole), benzodiazepines (eg, clonazepam), certain anticonvulsants (eg, gabapentin) and others.
Additional Sleep Information and Suggested Readings
Mindell, JA and Owens, JA. A Clinical Guide to Pediatric Sleep: Diagnosis and Management of Sleep Problems. Philadelphia, PA: Lippincott Williams and Wilkins, 2003.
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 1/26/2009…#14308