Periodic limb movement disorder

Clinic

• PLMD is a sleep disorder where the patient moves limbs involuntarily and periodically during sleep, which can lead the patient to wake up
• It sometimes called nocturnal myoclonus
• It often only last the first half of the night during non-REM sleep stages.
• It mostly happens in the lower limbs but can also appear in the upper extremities

• Diagnosis of PLMD cannot be used when narcolepsy, restless legs syndrome, REM sleep behaviour disorder (RBD) or untreated obstructive sleep apnea (OSA) is already diagnosed, since abnormal movements during sleep are frequent in these disorders.

PLMD vs RLS

PLMD should not be confused with restless legs syndrome.

• RLS is characterized by a voluntary response to an urge to move legs due to discomfort.
• PLMD is involuntary and the patient is often unaware of these movements altogether.

• RLS patients had significantly more REM sleep and less stage 1 sleep compared to PLMD patients

PLMD vs PLMS

• Periodic limb movements (PLMS) occurring during daytime period
• Only PLMS during sleep can suggest a diagnosis of PLMD.

PLMS vs RLS

• PLMS can be found but are considered as a symptom of RLS.
• Although evidence for differences between those two sleep disorders was found in literature.

Sign / Symptoms

• Excessive daytime sleepiness (EDS)
• Falling asleep during the day
• Trouble falling asleep at night
• Difficulty staying asleep throughout the night.
• PLMS can be unilateral or bilateral and not really symmetrical or simultaneous.
• PLMI was significantly higher in patients with PLMD.

PLMD vs RBD

• PLMD often only last the first half of the night during non-REM sleep stages.
• Movements do not occur during REM because of muscle atonia.

Causes

• Unknown etiology, but in many cases the patient also has other medical problems such as Parkinson's disease or narcolepsy.
• For women, the presence of musculoskeletal disease, heart disease, obstructive sleep apnea, cataplexy, doing physical activities close to bedtime and the presence of a mental disorder were significantly associated with having a higher risk of both PLMD and RLS.
• PLMS seems to have an origin in the spinal cord. In fact, PLMS was suggested to be associated with increased spinal reflexes. Manifestations of PLMS seem to occur mostly in disorders associated with dopaminergic dysfunctions.