What is Periodic Limb Movement Disorder (PLMD)?

Periodic Limb Movement Disorder (PLMD) refers to repetitive cramping or jerking of the leg during sleep that is so powerful it can wake you up during the night. The same disorder can occur during the day when you are awake (PLMW), but the nighttime version (PLMS) is more common and disruptive.

Signs & Symptoms of PLMD

When you experience PLMD during sleep, you may frequently extend your big toe, while your knee, or ankle might also move rapidly; as frequently as every 20 to 40 seconds for as long as 2 minutes at a time. There is a rhythm to the movements, which can result in kicking and thrashing. The pattern of PLMD can change from night to night so that one or both legs, as well as your upper arms, are involved.

As a result of this nighttime movement, you may feel fatigued without knowing why the next day, even if you think you had a full night of sleep. Many who suffer from PLMD are unaware of their nighttime activities unless they share a bed with another person who reports the phenomenon. Since this condition does not result in waking up, it is not technically a sleep disorder. The problem is, however disruptive to sleep.

While PLMD is prevalent in the elderly, with over 34% of people over 60 years old experiencing symptoms, it can disrupt the sleep of children and adults of all ages.

What Causes PLMD?

The medical community is still unaware of what causes primary periodic limb movement disorder, although it is assumed to result from abnormal patterns of nerves passage from the brain to the limbs. Previously, the condition was called nocturnal myoclonus, as the muscle contractions were viewed as similar to seizures, but this link has been disproved. Secondary PLMD, the result of having another condition, has been linked to conditions such as:

  • Spinal cord injuries or tumors
  • Diabetes or other medical conditions
  • Mental health issues
  • Sleep apnea or breathing difficulties that disrupt sleep
  • Sleep-related eating disorders close (SRED)
  • Uremia, or buildup of waste products in the blood from malfunctioning kidneys
  • Pregnancy
  • Parkinson’s disease
  • Multiple sclerosis (MS)
  • Posttraumatic stress disorder
  • ADHD (attention deficit/hyperactivity disorder)

Other Conditions Associated With PLMD?

People who have other sleep disorders frequently have PLMD. These related conditions include:

  • Narcolepsy or the urge to sleep during the day
  • Restless leg syndrome (RLS)
  • REM sleep behavior disorders (RBD)

It is also been linked to:

  • Iron deficiency
  • Anemia or low levels of oxygen rich hemoglobin
  • Reactions to medications
  • Withdrawal from medication

Why You Should Seek Help For PLMD?

While the specific causes of periodic limb movement disorder are unknown, the problem is a real one that merits investigation by a medical professional. Feeling fatigued and poorly rested can have a serious impact on how you function every day.

If you are feeling fatigued, you should see a specialist at the Center for Sleep Medicine. They will evaluate your medical history, review your medications, and ask you about your lifestyle. While there are no specific tests that can identify PLMD, the doctor may order blood work, urine tests, and a full evaluative screening to see if you have other conditions or infections that are tied to this syndrome. To check specifically for periodic limb movement disorder, your specialist can order sleep lab testing or polysomnography to observe and document your leg movements. In some cases, he or she may refer you to a neurologist.

Treatment for PLMD

Once your physician agrees that you have the symptoms of PLMD, he or she may prescribe medications to address the symptoms. Common drugs include:

  • Benzodiazepine to suppress muscle contraction and sedate you to reduce periodic limb movements each hour. Variations such as clonazepam (Klonopin) are most often prescribed for PLMD.
  • Anticonvulsant agents such as gabapentin (neurontin) to reduce muscle contractions.
  • Dopaminergic agents such as levodopa/carbidopa (Sinemet) or pergolide (Permax) to increase dopamine, the neurotransmitter that regulates muscle movements in the brain.
  • Gaba receptor agonists reduce muscle contraction by inhibiting the release of neurotransmitters known to stimulate muscle contraction.

Treating the secondary causes of PLMD often diminishes the problem.

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