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What are Periodic Limb Movement Disorder (PLMD)?
Periodic limb movement disorder (PLMD), is a condition in which a person’s legs or arms twitch, cramp or move involuntarily and periodically during sleep. Previously, PLMD was referred to as nocturnal myoclonus - rapid, rhythmic contractions of the muscles often seen in seizures. However, PLMD is not myoclonus.
The movements encountered in PLMD are repetitive and rhythmic and typically occur every 20 to 40 seconds. These movements may sometimes occur five or more times in one hour, or on and off throughout the night during periods of non-REM sleep. Because the movements disrupt sleep and often lead to daytime sleepiness, PLMD is considered a sleep disorder. Usually, partial flexing of the big toe, knee, ankle and sometimes the hip are affected by these rhythmic episodes.
It is often associated with restless leg syndrome, but they are both different. Restless leg syndrome is a condition characterized by unpleasant sensations in the legs (and sometimes arms) while awake, and an uncontrollable urge to move them for relief. Most people with restless leg syndrome suffer from PLMD. However, those with PLMD do not suffer from restless leg syndrome. As PLMD causes you to be very tired during the day, it can have a detrimental effect on your health and well-being, leading to depression, bad memory, short attention span and fatigue. PLMD is more common amongst middle-aged and older people but can occur at any age.
Diagnosing Periodic Limb Movement Disorder (PLMD)
Your doctor will perform a thorough physical examination and medical history to ascertain the diagnosis of PLMD. It is helpful if you can provide a sleep diary detailing your sleep patterns. An Epworth Sleepiness scale will also be able to rate your sleep and show how it affects your daily life.
An overnight sleep study called a polysomnogram at a sleep center may have to be performed. This test charts your brain waves, heart beat, breathing, and also records your leg and arm movements. It is also useful in detecting any other sleeping disorders.
Most people with PLMD are not aware of their leg movements and will report the following symptoms:
- Difficulty in falling asleep
- Difficulty in staying asleep
- Difficulty in staying awake during the day
- Restless sleep
- Hot or cold feet
- Loss of hair on the legs (men)
Very often, the sleep of a bed partner is affected by leg movements involving one or both limbs. These symptoms may include:
- Knee, ankle and big toe joints bend as part of the movements
- Movements vary from slight to wild kicking and thrashing
- Movements are rhythmic and repetitive, occurring every 20 to 40 seconds
- Movements last for about 2 seconds
What Causes Periodic Limb Movement Disorder (PLMD)?
The cause of PLMD is unknown, although there are numerous factors that may influence this disorder.
PLMD is commonly found in people with the following sleeping disorders:
- Restless Leg Syndrome (RLS)
- REM sleep behavior disorder (RBD)
Underlying conditions that contribute to PLMD
Underlying medical conditions that contribute to PLMD include:
- Spinal cord injury
- Multiple system atrophy – a neurological disorder
- Sleep-related eating disorder (SRED)
- Low brain iron
- Poor circulation
- Metabolic disorders
- Kidney disease
- Rheumatoid arthritis
Medications that may cause and exacerbate PLMD
Certain medications may also cause and exacerbate PLMD:
- Some antidepressants
- Anti-nausea medication
Help for Periodic Limb Movement Disorder (PLMD)
The first step to treating any sleeping disorder is to determine whether there are any underlying causes such as anemia, diabetes or the use of certain antidepressants. Because PLMD is commonly associated with restless leg syndrome, the same medications are used. To date, the most effective medication for PLMD is also used to treat Parkinson’s disease. Sleeping tablets, some anti-seizure medication and narcotic pain killers may also be prescribed.
More Information for Periodic Limb Movement Disorder (PLMD)
Some tips to cope with PLMD
In order to manage the symptoms of PLMD, it may be helpful to improve your sleep hygiene. Follow these tips for a better night’s rest:
- Establish a regular bedtime and wake time schedule
- Reduce your intake of caffeine
- Avoid drinking alcohol before bedtime
- Drink less fluids before going to sleep
- Avoid eating heavy meals before bedtime
- Stop smoking, because the nicotine affects your natural sleep cycles
- Exercise regularly, but preferably during the daytime (before noon)
- Practice relaxation techniques such as yoga, meditation and deep breathing exercises
- Massage the affected area to relieve any discomfort
- Soak in hot bath to relax your muscles and ease tension before bedtime
- Keep a sleep diary to monitor your sleeping patterns