Periodic limb movement disorder
is characterized by periodic episodes of repetitive and highly stereotyped limb movements
that occur during sleep.
The limb movements usually occur in the legs and consist of extension of one big toe in
combination with partial flexion of the ankle, knee, and sometimes hip. Similar movements
can also occur in the upper limbs. The movements are often associated with a partial
arousal or awakening; however, the patient is usually unaware of the limb movements or
sleep disruption. Between the episodes, the legs are still. There can be various numbers
of movements a night.
There may be a history of frequent nocturnal awakenings and unrefreshing of sleep.
Patients who are unaware of the sleep interruptions may have symptoms of excessive
sleepiness. It is probable that the nature of the patient’s complaint is affected by
the frequency of the movement as well as the associated awakenings.
The clinical significance of the movements needs to be decided on an individual basis.
Periodic limb movements may be an incidental finding, and medication that reduces the
number of limb movements can produce little or no change in sleep duration or sleep
efficiency.
It is possible that Central Nervous System mediated event can give rise to both the
periodic movements and the related sleep disturbance it is necessary to integrate the
clinical history and the polysomnographic findings to assess the role of this phenomenon
in a sleep disorder.
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