Nocturnal myoclonus
Encyclopedia
Periodic limb movement disorder (PLMD), previously known as nocturnal myoclonus, is a sleep disorder
where the patient moves limbs
involuntarily during sleep, and has symptoms or problems related to the movement.
PLMD should not be confused with restless leg syndrome (RLS). RLS occurs while awake as well as when asleep, and when awake, there is a voluntary response to an uncomfortable feeling in the legs. PLMD on the other hand is involuntary, and the patient is often unaware of these movements altogether.
PLMD is diagnosed with the aid of a polysomnogram or PSG. PLMD is diagnosed by first finding PLMS on a PSG, then integrating that information with a detailed history from the patient and/or bed partner. PLMS can range from a small amount of movement in the ankles and toes, to wild flailing of all four limbs. These movements, which are more common in the legs than arms, occur for between 0.5 and 5 seconds, recurring at intervals of 5 to 90 seconds. A formal diagnosis of PLMS requires three periods during the night, lasting from a few minutes to an hour or more, each containing at least 30 movements followed by partial arousal or awakening.
or narcolepsy
. Factors that increase the likelihood of PLMD in the absence of restless leg syndrome include being a shift worker, snoring, coffee drinking, stress, and use of hypnotics, particularly in the case of benzodiazepine withdrawal. For women, the presence of musculoskeletal disease, heart disease, obstructive sleep apnea
, cataplexy, doing physical activities close to bedtime and the presence of a mental disorder were significantly associated with having a higher risk of both PLMD and restless legs syndrome.
(RLS) - a study of 133 people found that 80% of those with RLS also had PLMS. However the opposite is not true: many people who have PLMD do not also have restless legs syndrome.
It is also advised to not consume caffeine, alcohol or antidepressants as these substances could worsen the PLMD symptoms.
Other medications aimed at reducing or eliminating the leg jerks or the arousals can be prescribed. Non-ergot
derived dopamine
rgic drugs (pramipexole
and ropinirole
) are preferred. Other dopaminergic agents such as co-careldopa, co-beneldopa, pergolide
, or lisuride
may also be used. These drugs decrease or eliminate both the leg jerks and the arousals. These medications are also successful for the treatment of restless legs syndrome
.
In one study, co-careldopa was superior to dextropropoxyphene
in decreasing the number of leg kicks and the number of arousals per hour of sleep. However, co-careldopa and, to a lesser extent, pergolide may shift the leg movements from the nighttime to the daytime.
Clonazepam, (Klonopin)
, in doses of 1 mg has been shown to improve objective and subjective measures of sleep.
Sleep disorder
A sleep disorder, or somnipathy, is a medical disorder of the sleep patterns of a person or animal. Some sleep disorders are serious enough to interfere with normal physical, mental and emotional functioning...
where the patient moves limbs
Limb (anatomy)
A limb is a jointed, or prehensile , appendage of the human or other animal body....
involuntarily during sleep, and has symptoms or problems related to the movement.
PLMD should not be confused with restless leg syndrome (RLS). RLS occurs while awake as well as when asleep, and when awake, there is a voluntary response to an uncomfortable feeling in the legs. PLMD on the other hand is involuntary, and the patient is often unaware of these movements altogether.
Symptoms
Patients with PLMD will complain of excessive daytime sleepiness (EDS), falling asleep during the day, trouble falling asleep at night, and difficulty staying asleep throughout the night. Patients also display involuntary limb movements that occur at periodic intervals anywhere from 20–40 seconds apart. They often only last the first half of the night during non-REM sleep stages. Movements do not occur during REM because of muscle atonia.Diagnosis
People with PLMD often do not know the cause of their excessive daytime sleepiness and their limb movements are reported by a spouse or sleep partner.PLMD is diagnosed with the aid of a polysomnogram or PSG. PLMD is diagnosed by first finding PLMS on a PSG, then integrating that information with a detailed history from the patient and/or bed partner. PLMS can range from a small amount of movement in the ankles and toes, to wild flailing of all four limbs. These movements, which are more common in the legs than arms, occur for between 0.5 and 5 seconds, recurring at intervals of 5 to 90 seconds. A formal diagnosis of PLMS requires three periods during the night, lasting from a few minutes to an hour or more, each containing at least 30 movements followed by partial arousal or awakening.
Causes
It is mostly unknown what causes PLMD, but in many cases the patient also suffers from other medical problems such as Parkinson's diseaseParkinson's disease
Parkinson's disease is a degenerative disorder of the central nervous system...
or narcolepsy
Narcolepsy
Narcolepsy is a chronic sleep disorder, or dyssomnia, characterized by excessive sleepiness and sleep attacks at inappropriate times, such as while at work. People with narcolepsy often experience disturbed nocturnal sleep and an abnormal daytime sleep pattern, which often is confused with insomnia...
. Factors that increase the likelihood of PLMD in the absence of restless leg syndrome include being a shift worker, snoring, coffee drinking, stress, and use of hypnotics, particularly in the case of benzodiazepine withdrawal. For women, the presence of musculoskeletal disease, heart disease, obstructive sleep apnea
Obstructive sleep apnea
Obstructive sleep apnea or obstructive sleep apnea syndrome is the most common type of sleep apnea and is caused by obstruction of the upper airway. It is characterized by repetitive pauses in breathing during sleep, despite the effort to breathe, and is usually associated with a reduction in...
, cataplexy, doing physical activities close to bedtime and the presence of a mental disorder were significantly associated with having a higher risk of both PLMD and restless legs syndrome.
Epidemiology
PLMD is estimated to occur in approximately 4% of adults (aged 15–100), but is more common in the elderly, especially females, with up to 11% experiencing symptoms. PLMS appears to be related to restless legs syndromeRestless legs syndrome
Restless legs syndrome or Willis-Ekbom disease is a neurological disorder characterized by an irresistible urge to move one's body to stop uncomfortable or odd sensations. It most commonly affects the legs, but can affect the arms, torso, and even phantom limbs...
(RLS) - a study of 133 people found that 80% of those with RLS also had PLMS. However the opposite is not true: many people who have PLMD do not also have restless legs syndrome.
Treatment
PLMD is often treated with anti-Parkinson's medication. These include anticonvulsants, benzodiazepines, and narcotics. Patients must stay on these medications in order to experience relief for there is no known cure for this disorder.It is also advised to not consume caffeine, alcohol or antidepressants as these substances could worsen the PLMD symptoms.
Other medications aimed at reducing or eliminating the leg jerks or the arousals can be prescribed. Non-ergot
Ergot
Ergot or ergot fungi refers to a group of fungi of the genus Claviceps. The most prominent member of this group is Claviceps purpurea. This fungus grows on rye and related plants, and produces alkaloids that can cause ergotism in humans and other mammals who consume grains contaminated with its...
derived dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
rgic drugs (pramipexole
Pramipexole
Pramipexole is a non-ergoline dopamine agonist indicated for treating early-stage Parkinson's disease and restless legs syndrome...
and ropinirole
Ropinirole
Ropinirole is a non-ergoline dopamine agonist. It is manufactured by GlaxoSmithKline , Cipla and Sun Pharmaceutical. It is used in the treatment of Parkinson's disease...
) are preferred. Other dopaminergic agents such as co-careldopa, co-beneldopa, pergolide
Pergolide
Pergolide is an ergoline-based dopamine receptor agonist used in some countries for the treatment of Parkinson's disease....
, or lisuride
Lisuride
Lisuride is an antiparkinson agent of the iso-ergoline class, chemically related to the dopaminergic ergoline Parkinson's drugs. Lisuride is described as free base and as hydrogen maleate salt.Lisuride is used to lower prolactin and, in low doses, to prevent migraine attacks...
may also be used. These drugs decrease or eliminate both the leg jerks and the arousals. These medications are also successful for the treatment of restless legs syndrome
Restless legs syndrome
Restless legs syndrome or Willis-Ekbom disease is a neurological disorder characterized by an irresistible urge to move one's body to stop uncomfortable or odd sensations. It most commonly affects the legs, but can affect the arms, torso, and even phantom limbs...
.
In one study, co-careldopa was superior to dextropropoxyphene
Dextropropoxyphene
Dextropropoxyphene, manufactured by Eli Lilly and Company, is an analgesic in the opioid category. It is intended to treat mild pain and has, in addition, anti-tussive and local anesthetic effects. It has been taken off the market in Europe and the US due to concerns of fatal overdoses and...
in decreasing the number of leg kicks and the number of arousals per hour of sleep. However, co-careldopa and, to a lesser extent, pergolide may shift the leg movements from the nighttime to the daytime.
Clonazepam, (Klonopin)
Clonazepam
Clonazepamis a benzodiazepine drug having anxiolytic, anticonvulsant, muscle relaxant, and hypnotic properties. It is marketed by Roche under the trade name Klonopin in the United States and Rivotril in Australia, Brazil, Canada and Europe...
, in doses of 1 mg has been shown to improve objective and subjective measures of sleep.