Periodic Limb Movements in Sleep (PLMS)

Jane is a 55 year old woman who, despite a good 8 hours sleep, wakes up tired every morning. Her husband gets annoyed when she kicks her legs a lot during the night. She saw a sleep specialist doctor who diagnosed her with periodic limb movements disorder (PLMD). Her sleep study showed that she was kicking more than 30 times an hour. With treatment, she is waking up refreshed (so does her husband).

Periodic limb movements of sleep (PLMS) refers to involuntary leg jerks that occur periodically during sleep. When they are disruptive to sleep, they are called periodic limb movements disorder (PLMD) and they lead to daytime fatigue and sleepiness, which is what Jane had. PLMS are often not disruptive and found incidentally on the sleep studies. These leg movements are more noted in the elderly and in folks with chronic conditions such as heart disease or diabetes.

Periodic limb movements of sleep are different from restless legs syndrome (RLS). RLS is an urge or a twitching sensation in the leg(rarely in the arms) that occur with rest and get better with movements. RLS occur when the person is awake. PLMS occurs during sleep and diagnosed on the sleep study. A person who has PLMS on the sleep study does not mean they automatically have restless legs. However, about 80% of the people with restless legs syndrome (RLS) also have PLMS.

What causes PLMS? No specific cause is known to date. However, we know that people with RLS also have PLMS but most cases have no known medical condition.

How do you diagnose PLMS? It is diagnosed through the sleep study by electrical leads that are placed on the legs. The reading physician will see periodic increases in muscle activity in the calve muscles. Again, many people with PLMS have no clinical effect from it. The sleep study will help determine if these leg jerks are causing arousals and awakening. If that is the case, treatment might be needed. Treatment is similar to that of RLS

Treatment

  • There are no FDA approved medications for PLMS or PLMD.
  • However, sleep medicine doctors use the same treatment for restless legs syndrome: mirapex and requip can be used. Other medications that have shown benefit include gabapentin, clonazepam, pramipexole or ropirinole.
  • Avoid caffeine and alcohol.
  • Encourage exercise.
  • Before medications are started, it is important to talk to the experience doctor about whether PLMS/D  are actually causing your sleep problems or not and the appropriate treatment is implemented.
  • Sometimes treatment of sleep apnea can diminish these leg movements, there medications might not be needed.