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Periodic Limb Movement Disorder Definition

Periodic Limb Movement Disorder (PLMD) is a type of sleep disorder which involves involuntary movements of the limbs or legs. PLMD is considered to be a sleep disorder as it causes disturbances of sleep, thereby leading to daytime sleepiness. It is also the only type of movement disorder that takes place only during sleep.

Periodic Limb Movement Disorder Epidemiology

PLMD occurs in almost 4% of adults, or people aged between 15 and 100. It is more common in elderly patients, especially females. Around 11% of females have been found to experience the symptoms of PLMD. It often occurs alongside restless legs syndrome (80%).

Periodic Limb Movement Disorder Causes

PLMD can be either primary or secondary. There are no known causes for the primary form of the condition. The disorder has been connected to abnormalities in the regulation of nerves traversing from brain to the legs. However, the nature of the abnormalities associated with the condition is not known. The secondary variant, on the other hand, can result from an underlying medical issue. Some of the medical factors that lead to PLMD are also responsible for Restless Legs Syndrome. The various factors that may lead to or increase the risk for PLMD have been listed below.

  • Uremia
  • Anemia
  • Narcolepsy
  • Iron deficiency
  • Diabetes mellitus
  • Spinal cord injury
  • Spinal cord tumor
  • Parkinson’s disease
  • William’s Syndrome
  • Sleep apnea syndrome
  • Attention deficit hyperactivity disorder (ADHD)
  • Medications – Neuroleptics or other antidopaminergic agents like Haldol, tricyclic antidepressants like amitriptyline (Elavil), lithium, selective serotonin reuptake inhibitors (SSRI), certain anticonvulsants or dopaminergic agents like Sinemet (even though Sinemet is frequently used as a cure for PLMD)
  • Withdrawal from certain sedative medicines such as benzodiazepines or barbiturates

The following conditions were found to significantly increase the risk for both restless legs syndrome and periodic limb movement disorder in women:

  • Cataplexy
  • Heart diseases
  • Mental disorders
  • Obstructive sleep apnea
  • Musculoskeletal diseases
  • Physical activities or hectic work close to bedtime

Apart from the causes mentioned above, there are also certain other factors that might lead to PLMD. These include:

  • Working in shifts
  • Stress
  • Snoring
  • Overconsumption of coffee

Periodic Limb Movement Disorder Symptoms

The term “Periodic” points to the repetitive and rhythmic motion of the legs that occur in about every 20 to 40 seconds. This repetitive jerking or cramping of the legs was previously referred to as “Nocturnal myoclonus” or “Sleep myoclonus”. These movements may show fluctuations in severity within a single night or from one night to another. Although they generally involve the legs, movements of the upper extremities may also be seen.

PLMD sufferers exhibit various signs and symptoms, such as:

  • Excessive daytime sleepiness (EDS)
  • Difficulty in falling asleep during nighttime
  • Falling asleep during day
  • Difficulty in staying asleep through the entire night

The patients also experience involuntary leg movements that take place at regular, periodic intervals ranging anywhere from 20 to 40 seconds apart. These movements last for the early hours of the night, primarily during the non-REM stages of sleep. They may range from being mild to being strenuous and may include thrashing and wild kicking. The leg movements might lead to multiple awakenings and fragmented sleep. Most PLMD patients are unaware of these involuntary leg movements unless notified by their bed partner. The movements cease to occur during the REM stage due to muscle atonia. Many times, children having PLMD might not appear sleep deprived but manifest other symptoms such as hyperactivity, irritability and impulsivity.

Periodic Limb Movement Disorder in Children

Instances of PLMD affecting children have only been identified very recently. Although information as to the exact rate of prevalence of this condition among children is scarce, it has been closely associated with restless legs syndrome. Another condition that is often observed alongside periodic limb movement disorder is attention deficit hyperactivity disorder (ADHD).

Children who experience difficulty in sleeping may show signs and symptoms such as:

Irritability
Oppositional behaviors
Throwing tantrums
Frequent yelling
Frustration
Episodes of angry outbursts

Periodic Limb Movement Disorder Diagnosis

The diagnosis for PLMD is based on clinical history, a thorough physical exam and also the results of an overnight polysomnogram or PSG. A polysomnogram is a diagnostic test that records sleep as well as the bioelectrical signals that come from the sleeping body. A complete neurological examination needs to be performed as well. Respiratory monitoring during PSG permits the diagnostician to rule out possibility of sleep-disordered breathing as the cause for disrupted sleep and intense muscle activity. Sometimes, additional sleep laboratory testing might be useful. A doctor might also recommend conducting blood work to check on vitamin B12, folic acid, iron, magnesium levels and thyroid functions. Urine samples may be gathered to check for presence of drugs that might lead to sleep problems.

Periodic Limb Movement Disorder Differential Diagnosis

A number of conditions are characterized by the leg movement features typical of PLMD. It is important to differentiate PLMD from such conditions during diagnosis in order to make sure that a patient receives the best possible treatment. The differential diagnosis for PLMD includes ensuring the absence of such conditions as:

  • Chorea
  • Narcolepsy
  • Epileptic seizures
  • Parkinson Disease
  • Tourette syndrome
  • Uremic Neuropathy
  • Various Tic Disorders
  • Frontal Lobe Epilepsy
  • Uremic Encephalopathy
  • Temporal Lobe Epilepsy
  • Restless Legs Syndrome
  • Complex Partial Seizures
  • Parkinson-Plus Syndromes
  • Epilepsia Partialis Continua
  • Early Myoclonic Encephalopathy
  • Psychogenic Nonepileptic Seizures

Periodic Limb Movement Disorder Treatment

Treatment is mainly aimed at relieving the symptoms of the condition and giving the patient relief. The treatment for PLMD involves:

Medications

PLMD is frequently treated by using anti-Parkinson medications. Other medications that might be used to treat this condition include anticonvulsants, narcotics and benzodiazepines. Anticonvulsant agents like gabapentin (Neurontin) help in reducing muscle convulsions. Benzodiazepines help in suppressing muscle contractions. They also act as sedatives that aid in sleeping through the movements. The drug Clonazepam has been proven effective in reducing the number of periodic leg movements occurring per hour. It stands as one of the most predominantly used drugs for the treatment of PLMD. Patients must keep on taking these medications as long as recommended by the physician as there is no other known cure for this sleeping disorder. The symptoms and signs of PLMD tend to get exacerbated by SSRIs, tricyclic antidepressants, sleep deprivation and stress. Sufferers are also advised not to consume substances such as antidepressants, alcohol or caffeine as they could worsen their condition.

Ropinirole and pramipexole are non-ergot-derived dopaminergic drugs that help in eliminating leg jerks or arousals experienced by the patient. Other dopaminergic medications such as co-beneldopa, co-careldopa, lisuride or pergolide may also be utilized to achieve the same effect. These drugs help in increasing the levels of dopamine, an important neurotransmitter which regulates muscle movements and either decreases or completely eliminates both leg jerks as well as the arousals. They are also widely used for treating Restless Legs Syndrome. GABA agonists are another group of medications used to treat PLMD. These agents prevent the release of certain specific neurotransmitters that facilitate muscle contractions. An example of such GABA agonists used in treating PLMD is the baclofen (Lioresal).

Natural Remedies

Patients may also try out the various natural remedies that are recommended to treat this condition. These include Horse Chestnut (Aesculus hippocastum), Butcher’s Broom (Ruscus acluteatus) and Astragalus membranaceous.

Therapy cannot cure PLMD; instead it can help in alleviating the symptoms.

Periodic Limb Movement Disorder Prognosis

The outcome of PLMD depends on whether the condition affecting an individual is primary or secondary. Primary PLMD may turn out to be chronic or permanent. Many patients having primary PLMD have experienced improved nighttime sleep with treatment. However, their condition might relapse with time. Secondary PLMD often ceases with appropriate treatment of underlying causes.

References:

http://www.webmd.com/sleep-disorders/guide/periodic-limb-movement-disorder

http://www.emedicinehealth.com/periodic_limb_movement_disorder/article_em.htm

http://my.clevelandclinic.org/disorders/periodic_limb_movement_disorder/hic_periodic_limb_movement_disorder.aspx

http://my.clevelandclinic.org/childrens-hospital/health-info/diseases-conditions/neurological-conditions/hic-periodic-limb-movement-disorder-in-children-and-adolescents.aspx


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