Periodic Limb Movements During Sleep

Definition and Diagnostic Criteria

Periodic limb movements during sleep (PLMS) are specifically defined as brief (0.5-10 seconds), recurrent movements of the lower extremities that occur approximately every 15-30 seconds during sleep, particularly during the first 4 hours of the sleep period, according to the American Academy of Sleep Medicine (AASM) guidelines 3, 4
The diagnosis of Periodic Limb Movement Disorder (PLMD) requires frequent PLMS (>15 events/hour in adults, >5 events/hour in children), clinically significant sleep disturbance not better explained by another disorder, and absence of other sleep disorders associated with high rates of PLMS, as recommended by the American Academy of Sleep Medicine (AASM) 4
The American Academy of Sleep Medicine (AASM) guidelines specify that the diagnosis of PLMD should be based on the presence of frequent PLMS and clinically significant sleep disturbance, with the absence of other sleep disorders associated with high rates of PLMS 3, 4

For proper diagnosis of PLMD, clinicians should use electromyography (EMG) during polysomnography (PSG) to measure PLMs during confirmed sleep periods only, as recommended by the American Academy of Sleep Medicine (AASM) 6, 8
The American Academy of Sleep Medicine (AASM) guidelines recommend that actigraphy should not be substituted for EMG in diagnosing PLMD, as actigraphy produces unreliable estimates of periodic limb movements 6, 7, 8
Clinicians should consider that the periodic limb movements of sleep index (PLMSI) varies significantly night-to-night in both adults and children, according to the American Academy of Sleep Medicine (AASM) guidelines 3, 4