Periodic limb movement disorder

Periodic Limb Movement Disorder or PLMD or sleep myoclonus or nocturnal myoclonus is a form of Periodic Leg Movements of Sleep (PLMS) involving very frequent movements that disturb the quality of sleep. Patients with PLMD are normally unaware of the movements, and it can only be diagnosed via polysomnography (PSG). The International Classification of Sleep Disorders, 2nd edition (ICSD-2) defines PLMD as: "periodic episodes of repetitive, highly stereotyped, limb movements that occur during sleep (PLMS)". Both arm and leg movements can occur, but leg movements are much more common, and PLMD is diagnosed only when there are a minimum of 15 stereotyped movements per hour during sleep, particularly extension of the big toe or ankle, and sometimes knee or hip flexing.

Signs and symptoms

 * Fatigue
 * Unrefreshing sleep or non-restorative sleep
 * Daytime tiredness or sleepiness

The World Health Organization classes PLMD as a sleep disorder associated with a "clinical sleep disturbance or a complaint of daytime fatigue that cannot be better explained by another cause".

ME/CFS
Periodic Limb Movement Disorder is recognized as a common comorbidity of ME/CFS by the U.S. ME/CFS Clinician Coalition (2020). and is particularly common in people with Restless Leg Syndrome, which also affects many people with ME/CFS.

Possible causes
PLMD is more common in people aged over 70, people with restless legs syndrome, which causes urges to regularly move legs in the daytime, neurodegenerative diseases such as Parkinson's disease, people with diabetes, and low iron and certain other medical conditions.

The movements can also be related to use of certain medications including lithium, a mood stabilizer used got bipolar disorder, tricyclic antidepressants (TCAs) such as amitriptyline, and selective serotonin reuptake inhibitors (SSRIs), which should be ruled out before diagnosis.

Treatment
A number of different medications have shown positive results in patients with PLMD, although many were very small clinical trials.

Learn more

 * Periodic Limb Movements - Sleep Education, American Academy of Sleep Medicine