Parasomnias

Parasomnias are characterized by movements or behaviors that do not normally occur during sleep.

Geriatric Essentials

• With aging, periodic limb movement disorder becomes common but is often unrecognized.
• Periodic limb movement disorder should be considered in elderly patients with excessive daytime sleepiness.
• REM sleep behavior disorder should be considered in elderly patients with disruptive or violent nocturnal behavior, even if the behavior is presumed to be secondary to dementia.
• Restless legs syndrome should be considered in elderly patients with symptoms of leg discomfort or excessive leg movements during sleep.

Because parasomnias affect initiation and maintenance of sleep or cause excessive daytime sleepiness, they are more correctly termed dyssomnias. They include restless legs syndrome and periodic limb movement disorder, which are common among the elderly, and REM sleep behavior disorder, which occurs primarily in the elderly. Other parasomnias (eg, somnambulism, night terrors) usually occur in children.

Periodic Limb Movements of Sleep

Periodic limb movement disorder is characterized by repetitive stereotypical movements, mainly of the legs, that occur during sleep and by unexplained sleep dysfunction.

Periodic limb movements of sleep occur in up to 45% of community-dwelling people > 65. However, most people are unaware of the movements. The disorder periodic limb movement disorder (PLMD) is characterized by periodic limb movements of sleep plus sleep dysfunction that is not otherwise explained by another sleep disorder. The cause of PLMD is unknown. Because PLMD responds to dopamine agonists, an age-related decrease in dopamine receptors has been suggested as a cause.

Periodic limb movements of sleep often manifest as unilateral or bilateral flexion of the big toe, rapid flexion of the ankle, and partial flexion of the knee and hip. Upper extremities may also move. The movements occur during NREM sleep. Movement lasts 2 to 4 sec and occurs throughout the night, sometimes as often as every 20 to 40 sec. The movement may arouse patients from sleep (although most patients are not aware of waking); interrupted nocturnal sleep or excessive daytime sleepiness may be the only symptom. Most patients have no symptoms.

PLMD should be suspected in elderly patients with unexplained frequent nocturnal awakenings or unexplained excessive daytime sleepiness. Bed clothing may be in disarray in the morning. The bed partner may report movement of the patient's legs.

Patients should be referred to a sleep specialist for polysomnography to establish or confirm the diagnosis; treatment is needed only when the patient has impaired sleep or excessive daytime sleepiness. Dopamine agonists are the drugs of choice for the elderly. Carbidopa-levodopa or a dopamine agonist (eg, pramipexole, ropinirole) can be used at bedtime. However, bedtime use of these drugs may cause limb movements to develop during the day. If dopamine agonists are ineffective, a benzodiazepine (eg, clonazepam) may be effective, but in the elderly, risks of benzodiazepines are probably increased if use is chronic. Opioids are less safe than other drugs used to treat PLMD and are restricted to patients with severe symptoms refractory to other treatments.

REM Sleep Behavior Disorder

REM sleep behavior disorder is vigorous, sometimes injurious body movements that occur during REM sleep (normally, muscle paralysis occurs temporarily) and that are accompanied by vivid dreams.

REM sleep behavior disorder occurs primarily in the elderly, particularly those with degenerative brain disorders (eg, Parkinson's or Alzheimer's disease, vascular dementia, dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy). It is much more common among men than among women. REM sleep behavior disorder, particularly when acute, may also be caused by drug intoxication, drug withdrawal, or possibly use of certain drugs (eg, antidepressants). Normally during REM sleep (and thus during dreaming), skeletal muscle activity is inhibited, resulting in temporary muscle paralysis. In REM sleep behavior disorder, this inhibition is lost. Patients have vivid dreams and may say things (often profane) or move violently (eg, kicking, punching, waving the arms) during sleep, sometimes injuring themselves or their bed partner.

Diagnosis is by polysomnography in a sleep laboratory. Patients are advised to take precautions against injury (eg, removing potentially dangerous objects from the bedroom, putting cushions around the bed, possibly placing the mattress on the floor). The bed partner should also be protected; separate sleeping arrangements may be considered, at least temporarily until the disorder is controlled.

Traditionally, most patients have been treated with clonazepam 0.5 to 2 mg po at bedtime. However, some recent evidence suggests that melatonin may be effective and safer in patients with an underlying degenerative brain disorder (eg, dementia with Lewy bodies, Parkinson's disease, multiple system atrophy).

Restless Legs Syndrome

Restless legs syndrome is an uncomfortable sensation in one or both legs that is relieved by moving the affected leg or legs.

The cause of restless legs syndrome is unknown but may involve altered brain dopamine transmission. Risk factors include a family history, iron deficiency, peripheral neuropathies (eg, due to diabetes or uremia), Parkinson's disease, varicose veins, vitamin deficiencies, lumbosacral radiculopathy, spinal stenosis, excess caffeine intake, use of mianserin, hypoglycemia, hypothyroidism, and possibly rheumatic disorders.

A creeping or crawling sensation occurs in one or both legs when patients recline. To relieve symptoms, patients move the affected leg by stretching, kicking, or walking. As a result, they have difficulty falling asleep, repeated nocturnal awakenings, or both. Restless legs syndrome differs from idiopathic leg muscle cramps, which are characterized by calf pain and muscle spasms, typically at night. Restless legs syndrome differs from akathisia, which is a restlessness affecting the entire body and not typically preceded by creeping or crawling sensations. Diagnosis is by history.

Reassurance alone may be sufficient treatment. Walking, stretching, or rubbing the legs may help. If elderly patients have severe symptoms and do not respond to conservative treatment, dopamine agonists are the treatment of choice. Patients with infrequent symptoms can take carbidopa-levodopa as needed at bedtime. For patients with frequent or chronic symptoms, scheduled use of dopamine agonists (eg, pramipexole, ropinirole) is better. Benzodiazepines (eg, clonazepam) may also be effective, but risks are increased for the elderly if use is chronic. There is evidence that iron replacement therapy may relieve symptoms in patients with a low ferritin level. Evidence to support use of other suggested drugs (eg, carbamazepine, clonidine, gabapentin) is limited.

This topic was last updated March 2006.