What are Periodic Limb Movement Disorder (PLMD)?
Periodic limb movement disorder (PLMD), is a condition in which a person’s legs or arms twitch, cramp or move involuntarily and periodically during sleep. Previously, PLMD was referred to as nocturnal myoclonus – rapid, rhythmic contractions of the muscles often seen in seizures. However, PLMD is not myoclonus. The movements encountered in PLMD are repetitive and rhythmic and typically occur every 20 to 40 seconds. These movements may sometimes occur five or more times in one hour, or on and off throughout the night during periods of non-REM sleep. Because the movements disrupt sleep and often lead to daytime sleepiness, PLMD is considered a sleep disorder. Usually, partial flexing of the big toe, knee, ankle and sometimes the hip are affected by these rhythmic episodes. It is often associated with restless leg syndrome, but they are both different. Restless leg syndrome is a condition characterized by unpleasant sensations in the legs (and sometimes arms) while awake, and an uncontrol
