Periodic limb movement disorder

Overview

Periodic Limb Movement Disorder (PLMD) is a movement disorder that occurs during sleep. Approximately 80-90% of patients with Restless Legs Syndrome (RLS) will also have PLMD.

PLMD is characterised by repetitive limb movements during sleep. These movements usually involve the legs; however the arms may also be involved in severe cases. Abnormal limb movements result in daytime tiredness by causing periods of wakefulness during the night (called arousals) and disrupting the brain’s sleep-patterns. The abnormal movements also prevent the brain from transitioning into stages of deep sleep, causing the sufferer to wake feeling tired and unrefreshed. PLMD is also often disruptive for the sufferer’s bed partner.

Episodes of movement occur most commonly in the period soon after sleep-onset, but may not persist throughout the entire night. Both legs are usually affected, however the abnormal movements may occur in only one limb.

PLMD can occur in conjunction with other sleep-disorders, such as narcolepsy, snoring, obstructive sleep apnoea, or REM-behaviour disorders.

Diagnosis

The most effective way to diagnose PLMD is by having an overnight sleep study (a polysomnogram, or PSG). This measures leg movement using tiny sensors placed over the muscles of the legs. Abnormal leg movements are recorded throughout the night, and parallel recordings of brain waves makes it possible to identify arousals and quantify the severity of the disorder.

Treatment

There are several classes of medication which are effective in treating PLMD (and which are also used to treat RLS). These medications treat the symptoms of PLMD, and not the underlying cause. Consequently, they must be taken every evening before bed, otherwise the symptoms will return.

Medications which may be prescribed for you include dopaminergic medications, opioids, anticonvulsants and benzodiazepines). Your General Practitioner or Sleep Physician can advise you on what class of medication is most suitable for you.

Non-pharmacological treatments for PLMD should be used in conjunction with pharmacologic ones. If you have PLMD, you should:

  • Maintain good sleep hygiene, having regular bed times and rising times, ensure
  • you get at least 7 hours of sleep per night
  • Avoid being sleep-deprived, as this can exacerbate RLS and PLMD
  • Avoid caffeine, alcohol, nicotine and heavy meals before retiring to bed
  • Perform moderate physical activity during the day (such as brisk walking)
  • Avoid excessive physical exercise before bed-time, as this tends to make RLS and PLMD worse