**12. Diagnosis/Clinical significance**

RLS is diagnosed clinically. PLMD is diagnosed objectively with polysomnography, which reveals periodic, involuntary movements of the legs during sleep.

PLMD can be identified on a polysomnogram by examining spiked activity coming from the electromyogram (EMG), which measures muscle movement during sleep. Specifically, anterior tibialis recording is usually sufficient in detecting the periodic limb movement episodes. Periodic limb movements typically last 0.5-5 seconds in duration and usually occurs approximately every 20-40seconds. The severity is described in terms of leg movement per hour of sleep (periodic limb movement index, PLMI). PLMI >5 is considered abnormal. Additionally, the examination of EEG test results will indicate micro-arousals, which can also lead to a diagnosis. PLMD can occur independently of RLS, and is more common with advancing age (35). RLS is almost always associated with PLMD, but PLMD can occur in the absence of RLS.

RLS is associated with difficulty initiating sleep, poor sleep quality, and impaired health quality of life (48) (FIGURE-5). RLS has been associated with depression. PLMD has been associated with increased mortality in patient with ESRD (49).
