Introduction

Periodic Limb Movement Disorder (PLMD) is a sleeping disorder that causes unconscious movements, primarily in the legs, when one is asleep. A person with the disorder experiences restlessness at night and their sleep quality is significantly reduced. PLMD is commonly associated with other sleep disorders, including, daytime sleepiness, insomnia, restless legs syndrome (RLS), narcolepsy, and sleep apnea. It is caused by an over-excitement of the central nervous system when a person is asleep, thus causing unusual body movements. The disorder only manifests during Non-REM sleep since skeletal muscles are temporarily paralysed during REM sleep. Many health conditions are linked to PLMD, including uremia, diabetes, spinal cord injury, dopaminergic deficiency, and iron deficiency. PLMD has no specific treatments but it can be managed using medications, supplements, and lifestyle changes.

Symptoms

PLMD is characterized by unusual repetitive leg movements that occur when a person is asleep. The movements involve flexing, jerking, and cramping of the feet, and they take place every 20 to 40 seconds. They occur periodically and can last from several minutes to a few hours. These movements occur in the lower limbs, including the hips, knees, and ankles, and can occur on one or both legs. The individual with the disorder is not usually aware of these leg movements because they take place during sleep. They can, however, wake up several times during the night because of the sleep interruptions caused by the repetitive movements. PLMD, therefore, reduces one’s sleep quality due to frequent awakening and general restlessness. The condition also affects the daily activities of the individual by leading to the following observable signs:

  • Non-restorative sleep that causes the person to feel unrefreshed in the morning even after a long night’s sleep
  • Fatigue during the day
  • Daytime sleepiness
  • Insomnia
  • Poor concentration during the day

Causes

PLMD is categorized into two types, primary and secondary, based on its causes.

Primary PLMD

This is PLMD whose exact cause is not known. It is suggested that the condition may be caused by flaws in the nerve regulation between the brain and the limbs. Primary PLMD is not a serious condition but it can cause sleep disturbance.

Secondary PLMD

Secondary PLMD is caused by other underlying health conditions or medications used. Some of the medical conditions that are associated with secondary PLMD include:

1. Uremia

Uremia is a medical condition in which waste products build up in the blood. This build-up occurs because of impaired kidney function. A large number of individuals with PLMD most commonly have kidney problems. Uremia, on its own, is known to cause the classical symptoms of sleep disorders, such as daytime sleepiness, insomnia, and poor concentration, even when one does not have a confirmed sleeping disorder.

2. Cardiovascular disease

Cardiovascular disease is a general term for the illnesses that affect the different elements of the heart, including the blood vessels, heart muscles, and the heart rhythm. Studies show that individuals who experience severe PLMD have detrimental alterations in their cardiac structure. The left ventricular diameter is significantly increased making it abnormally massive. The increased size of the left ventricle causes an increase in nocturnal systolic blood pressure.

3. Spinal cord injury

Spinal Cord Injury (SCI) has been shown to trigger periodic leg movements in sleep. The injury causes the spinal cord to malfunction leading to increased spinal reflexes. One, therefore, becomes restless and experiences unconscious body movements in their sleep.

4. Iron deficiency anemia

Iron deficiency anemia is a medical condition in which the iron levels in the body are significantly reduced. The central nervous system is affected by the inadequacy leading to difficulties in normal cognitive function. Iron deficiency anemia is associated with many sleep disorders. It leads to poor neurological development and altered motor functions. One, therefore, experiences abnormal movements in the limbs when asleep due to the malfunction in the central nervous system. Iron deficiency anemia is usually commonly reported in pregnant women.

  1. Diabetes mellitus

The Periodic Limb Movement Disorder is prevalent in individuals who have diabetes mellitus, which is a group of metabolic disorders that cause high blood sugar levels over a long period. Diabetes increases the activity of the sympathetic nervous system, thus causing abnormal movements of the limbs when asleep. An individual who has diabetes is, therefore, at higher risk of the periodic limb movement disorder.

  1. Restless legs syndrome (RLS)

The Restless Leg Syndrome is a condition that causes an irresistible urge to move one’s legs. This condition is different from the periodic limb movement disorder in that it occurs during both wakeful and sleeping episodes. The Periodic Limb Movement Disorder and Restless Leg Syndrome, however, have many similarities in their symptoms.  Many individuals with the Periodic Limb Movement Disorder also have symptoms of the Restless Leg Syndrome.

7. Dopaminergic deficit

Dopamine is a neurotransmitter that sends signals to the brain. It helps in controlling body movements and vital brain functions, including sleep, memory, and mood. When a person has a dopamine deficiency, their body movements are not well regulated and this can lead to abnormal limb movements. A dopamine deficiency occurs when the amount synthesized in the body is insufficient or when there is a fault in the brain receptors.

Other than health conditions, the Periodic Limb Movement Disorder can also be caused by some medications including:

  • Neuroleptics
  • Antidopaminergic agents
  • Tricyclic antidepressants
  • Antihistamines
  • Antinausea medications
  • Antipsychotics
  • Sedatives

Risk factors

Several factors increase the risk of the Periodic Limb Movement Disorder including:

  • Older age
  • Feminine gender
  • Cardiovascular disease
  • Obstructive sleep apnea
  • Mental disorders
  • Taking stimulants, such as coffee before sleep
  • Use of sleep aids (drugs)
  • Stress

Diagnosis

The Periodic Limb Movement Disorder is commonly diagnosed based on the information provided by people around a patient because its symptoms occur when one is asleep. Therefore, friends and family can observe the unusual movements, which the person is not aware of, as they happen.  The patient can also inform the doctor of symptoms that may be related to the Periodic Limb Movement Disorder that occur during the day, such as daytime sleepiness, fatigue, and not feeling refreshed even after a long night’s sleep. When making a diagnosis of the Periodic Limb Movement Disorder, the doctor first eliminates all the other related sleep disorders before confirming the condition. Some of the tools that doctors use in diagnosis include:

1. Polysomnography

Polysomnography is an overnight sleep study that is commonly used to determine the underlying cause of a sleep disorder. It is used in the diagnosis of the Periodic Limb Movement Disorder to record and quantify the periodic limb movements experienced in sleep. An electromyogram (EMG) records the electrical activity in legs since muscles produce electrical current when active. EMG electrodes are connected on the patient’s limbs to record muscle activity that doctors can use to distinguish the disorder from normal involuntary movements during sleep. People around the patient can give false-negative and false-positive information on a person’s body movements that can affect the diagnosis. Hence, polysomnography is carried out to validate the information provided by friends and family to make a proper conclusion.

2. Sleep logs

The doctor can ask a patient to keep a sleep diary for about two weeks for use in diagnosis. The diary contains logs of the person’s sleeping habits, including:

  • Sleep and wake times
  • Activities carried out before bed
  • Food and drinks taken before bed
  • The condition of the sleeping environment

Other people can play a supportive role in keeping the diary by indicating in the sleep log any unusual activities that occur when the person is asleep. The information contained in a sleep diary is quite resourceful to doctors when confirming a case of a Periodic Limb Movement Disorder.

3. Auditory brainstem response (ABR) test

An ABR test is used to examine the hearing nerve’s response to sounds by measuring the electrical activity in the brain. Electrodes are placed on the scalp and used to record brain activity. This method is useful in studying the activity of the central nervous system and can be useful in identifying flaws in its function that can lead to the Periodic Limb Movement Disorder. People who have iron deficiency show a malfunction in the central nervous system that causes unusual body movements.

Treatment

There is no specific medical treatment for the Periodic Limb Movement Disorder because it is chronic. Thus, medications are mainly aimed at reducing or eliminating the symptoms of the condition. The medications are used frequently to provide continued relief and to enable patients to lead normal lives.  The common medications used for the Periodic Limb Movement Disorder are:

1. Dopaminergic agents

Dopamine deficiency is a major cause of the disorder because the hormone is required in controlling body movements. Dopaminergic agents are currently the most successful treatments for condition.  They work by increasing the dopamine levels in the body. The common dopaminergic agents used include:

  • Pergolide
  • Pramipexole
  • Ropinerole
  • Talipexole
  • Cabergoline,
  • Piribedil
  • alpha-dihydroergocryptine (DHEC)
  • Levodopa

2. Benzodiazepines

These are medications that work on the central nervous system to bring about different effects in the body, including sedation and muscle relaxation. In Periodic Limb Movement Disorders, they work by suppressing the muscle contractions and reducing the occurrence of limb movements. The patient can, therefore, sleep without interruptions throughout the night. The common benzodiazepine used for the disorder is clonazepam.

3. Anticonvulsant agents

Anticonvulsants are medications that normalize the transmission of nerve impulses in the nerve cells. They help regulate the function of the central nervous system. They tend to reduce muscle activity thus preventing unusual body movements when asleep. The common anticonvulsant used in treating the Periodic Limb Movement Disorder is gabapentin.

4. Gamma-aminobutyric acid-A (GABA) agonists

GABA agonists work by preventing the release of neurotransmitters that stimulate muscle contractions. They cause the muscles to relax when one is asleep thus helping people with the disorder to get undisturbed sleep throughout the night. The most widely used GABA agonist in treating the Periodic Limb Movement Disorder is baclofen.

 

Doctors will closely monitor people who are under medication to see the effectiveness of drugs and identify any adverse effects. Children, pregnant women, and the elderly are treated as special groups and evaluated regularly for early identification of side effects.

5. Treating the underlying health conditions

Secondary Periodic Limb Movement Disorder can be treated by identifying and eliminating the underlying health problems. The disorder is associated with many health conditions and treating them can reduce abnormal limb movements. For example, uremia is treated using hemodialysis and renal transplantation.

6. Iron supplements

Iron deficiency is a major cause of the Periodic Limb Movement Disorder. It causes the central nervous system to malfunction leading to abnormal body movements when a person is asleep. Iron supplements, which can be bought over the counter, have been found to significantly reduce the condition’s symptoms.

Natural treatment options

The Periodic Limb Movement Disorder can be managed using some natural methods and lifestyle changes, such as:

  • Regular physical activity, with high impact exercise during the day and simpler exercise in the evening.
  • Regular sleep-wake times
  • Adequate sleep
  • Avoiding caffeine, alcohol, and nicotine
  • Avoiding medications that can trigger the disorder, such as antihistamines and antipsychotics

Conclusion

The Periodic Limb Movement Disorder is a sleeping disorder whereby a person experiences movements in the lower limbs when asleep. The individual is not aware of the condition because the movements are experienced in sleep. The condition occurs during N-REM sleep in episodes lasting between minutes and hours. The movements disrupt one’s sleep causing one to wake up frequently during the night. The condition, therefore, leads to insomnia, non-restorative sleep, fatigue, and daytime sleepiness. When the cause of the disorder is unknown, the condition is referred to as primary PLMD, whereas when there is an underlying cause, the condition is called secondary PLMD. Secondary Periodic Limb Movement Disorder is caused by health conditions, such as dopaminergic deficiency, uremia, spinal cord injury, cardiovascular disease, iron deficiency anemia, and diabetes mellitus. It can also be caused by medications that affect the function of the central nervous system, including antihistamines, antidepressants, antipsychotics, and sedatives.

The risk of experiencing the disorder increases with old age, cardiovascular disease, mental disorders, and poor sleep hygiene. Women are at a higher risk of experiencing the condition than men. The disorder is diagnosed using different methods including sleep logs, polysomnography, and auditory brainstem response (ABR) tests. The information from people around patients plays a significant role in the diagnosis because the symptoms of the condition occur when a person is asleep. The disorder cannot be treated fully because it is a chronic condition, but some methods are used to manage it. Some common medications used to treat the Periodic Limb Movement Disorder include dopaminergic agents, benzodiazepines, anticonvulsants, GABA agonists, and iron, and other supplements. Treating the underlying health condition can help eliminate the symptoms of the disorder. The condition can also be managed using natural treatment options, such as changing one’s lifestyle habits, getting sufficient sleep, having a proper sleep hygiene, as well as, avoiding alcohol and other substances that affect one’s sleep patterns.

 

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