Limb Movement Disorders

Restless legs syndrome, periodic limb movements of sleep, and leg cramps are disorders in which a person experiences leg symptoms and movements while sleeping or trying to sleep.

The movements are usually involuntary, and they can keep older people from falling asleep or cause them to wake up once they have been asleep. The disorders are not a problem in themselves, but they require attention if they cause insomnia or daytime sleepiness.

Restless legs syndrome is an uncomfortable sensation in the legs (often described as a pulling, drawing up, or crawling of the legs) that seems to be relieved only by rubbing or moving the legs. It occurs while the person is awake, usually in the evening.

Periodic limb movements of sleep produces quick twitches or kicks of the leg that occur repeatedly during but not before sleep. The limb movements interfere with deep sleep, though the person may not be aware of it and simply feels unrested the next day.

Leg cramps are muscle spasms ("charley horses") that are temporarily relieved by moving the legs. Leg cramps can keep people from falling asleep or can wake them up at night.

Causes

Restless legs syndrome may occur because of iron deficiency, an imbalance of chemicals in the brain, or some unknown cause. Most people with restless legs syndrome also have periodic limb movements of sleep. The causes are unknown but may be the same. Restless legs syndrome and periodic limb movements of sleep can be worsened by drugs, such as lithium or certain antidepressants. These two disorders can also be worsened when people discontinue taking certain drugs, such as anticonvulsants or benzodiazepines.

Leg cramps may be caused by dehydration, abnormal electrolyte levels in the blood, and diuretics, but mostly they occur for no apparent reason.

Diagnosis

People with restless legs syndrome are aware of the disorder. Periodic limb movements of sleep may be suspected when a person's bed partner reports kicking but may be discovered in a laboratory sleep evaluation conducted for other reasons. People with leg cramps diagnose the disorder themselves, although a doctor may order blood tests to check for a cause.

Treatment

Daily exercise, including leg stretches, helps people with restless legs syndrome; hot baths or hot soaking of the legs may also help. People with iron deficiency may get relief with iron supplements. If these treatments are ineffective or if restless legs syndrome is severe, prescription drugs may be needed. Most commonly used are nighttime doses of antiparkinson drugs (such as levodopa with carbidopa, pramipexole, or ropinirole), anticonvulsants (such as carbamazepine or gabapentin), and benzodiazepines (such as clonazepam).

Treatment for periodic limb movements of sleep is similar to that for restless legs syndrome. Antiparkinson drugs are usually effective in low doses.

Leg cramps can be relieved by doing stretching exercises before bedtime. Keeping well hydrated is also important. Taking a hot bath or soaking the legs may help. In the past, some older people believed that taking quinine tablets relieved leg cramps. But quinine is no longer widely available in drug form because of uncertainty about its safety and benefits.

Outlook

The outlook for people with any of these disorders is good. Restless legs syndrome sometimes worsens with age but generally responds to treatment. Periodic limb movements of sleep can often be treated if recognized, but treatment may need to continue indefinitely. Leg cramps frequently resolve by themselves, but they may reappear again periodically for no apparent reason.

See the figure Stretching Exercises for Leg Cramps.