Most people experience some form of sleep disorder at one point or another. Some sleep disorders are well-known, but others are not. Periodic limb movement disorder (PLMD) belongs to the latter group and it’s time to learn something about it.
Formerly known as sleep myoclonus or nocturnal myoclonus, PLMD is a sleep disorder that involves repetitive or rhythmic limb movements during sleep. Estimates show that 4% to 11% of adults have this disorder and it rarely occurs in childhood. In addition, approximately 30% of people who are older than 65 have this disorder.
To get a clear indication of this sleep condition, watch the short video clip below.
What Causes PLMP?
We can categorize PLMD cases on primary and secondary. The exact cause that induces primary PLMD is unknown, but it is believed that nerve regulation difficulties play a role. Primary PLMD isn’t serious to one’s health.
On the other hand, secondary PLMD occurs due to underlying disorders of which restless leg syndrome (RLS) is the most common. In fact, 80% of people with RLS also have periodic limb movement disorder. Other health conditions and disorders associated with PLMD include diabetes, anemia, narcolepsy, iron deficiency, multiple system atrophy, obstructive sleep apnea, spinal cord injury and tumor, just to name a few.
PLMD can also be a side effect of some medications such as antihistamines, antidepressants, antipsychotics, and anti-nausea drugs.
Symptoms of PLMD
The primary symptom of PLMD is a rhythmic movement of limbs during sleep hence the name. Most people with this disorder move their legs, but the movement of upper extremities can also occur. These episodes vary in duration and intensity. Sometimes the episode lasts a few minutes only, but in other cases, it can take hours.
Most people are usually not aware they’re making movements with their legs (or arms). However, the disorder may cause problems for your partner who finds it difficult to fall asleep due to rhythmic movements of your limbs.
Common signs and symptoms of the disorder involve:
- Extension of the big toe
- Partial flexing of ankle, knee, and hip
Depending on severity, a patient may wake up from time to time. Although you’re not aware of the episodes, you may notice your sleep has become fragmented. As seen above, this disorder may go hand in hand with restless leg syndrome.
In the long run, people with PLMD may experience:
- Chronic insomnia
- Daytime sleepiness
- Short attention span
- Weak memory
Diagnosis of PLMD involves the use of an overnight polysomnogram (PSG), a test carried out in a sleep laboratory. The primary function of PSG is to record bodily functions while you sleep. Doctors generally use the test to identify the cause of recurring awakenings from sleep and daytime sleepiness. Prior to the test itself, the doctor carries out a physical exam to rule out other conditions and they may order blood tests to assess your magnesium, folic acid, vitamin B12 levels and thyroid function.
How is PLMD Treated?
Treatment depends on the severity of the disorder. In severe cases, the doctor may prescribe medications such as those used to address symptoms of Parkinson’s disease, narcotics, anticonvulsant drugs, and others. There is no cure that would eliminate PLMD entirely and treatment options are usually navigated toward alleviating symptoms of the disorder and decreasing their intensity. Doctors also advise patients to avoid or limit intake of caffeine and caffeine-containing products like tea. When PLMD is caused by an underlying health condition, then addressing that problem can also aid management of this sleep disorder.
Periodic limb movement disorder is a little-known sleep disorder that usually affects adults, particularly elderly, and it is common in people with restless leg syndrome. Although it’s not harmful, it can cause various complications such as fatigue, poor memory, and others. Treatment relies on addressing symptoms.