The diagnosis of Periodic Limb Movement Disorder (PLMD) requires periodic limb movements during sleep (PLMS) that occur more than 5 times per hour for children and more than 15 times per hour for adults, demonstrated on polysomnography. In addition, there must be a sleep complaint, such as insomnia, fatigue, or excessive daytime fatigue.9 10
PLMD is only diagnosed as a clinical condition when the PLMS (or their associated short arousals) exceed the norms for the person’s age and cause an otherwise unexplainable insomnia and/or excessive daytime fatigue.
Since body movements that disturb sleep are also seen in other disorders, other causes of hypersomnia, fatigue, and insomnia must be excluded. These other disorders or conditions include Restless Legs Syndrome (RLS), Sleep-Related Breathing Disorder, narcolepsy, Sleep-Related Eating Disorder, heart failure, Attention Deficit Hyperactivity Disorder (ADHD), William's Syndrome, Parkinson disease, and other conditions.11 12
PLMD is not diagnosed in the context of RLS, narcolepsy, untreated Obstructive Sleep Apnea Syndrome, or REM Sleep Behavior Disorder. When PLMD occur among individuals with these conditions, that diagnosis trumps the PLMD diagnosis.
9 Gingras JL, Gaultney JF, Picchietti DL. Pediatric periodic limb movement disorder: sleep symptom and polysomnographic correlates compared to obstructive sleep apnea. J Clin Sleep Med 2011;7:603–9.
10 Hornyak M, Feige B, Riemann D, Voderholzer U. Periodic leg movements in sleep and periodic limb movement disorder: prevalence, clinical significance and treatment. Sleep Med Rev 2006;10:169–77.
11 Koo BB, Blackwell T, Ancoli-Israel S, Stone KL, Stefanick ML, Redline S. Association of incident cardiovascular disease with periodic limb movements during sleep in older men: Outcomes of Sleep Disorders in Older Men (MrOS) Study. Circulation 2011;124:1223–31.
12 Pennestri MH, Whittom S, Adam B, Petit D, Carrier J, Montplaisir J. PLMS and PLMW in healthy subjects as a function of age: prevalence and interval distribution. Sleep 2006;29:1183–7.