Differentials
Periodic limb movement disorder (PLMD)
SIGNS / SYMPTOMS
Characterized by periodic episodes of repetitive limb movements during sleep, which most often occur in the lower extremities, including the toes, ankles, knees, and hips, and occasionally in the upper extremities. These movements may be associated with an arousal, and if so, sleep disruption can cause excessive daytime sleepiness.
Unlike in RLS, symptoms only occur during sleep and the patient is usually unaware of them; there is no urge to move the limbs for comfort or relief from movement.
INVESTIGATIONS
PLMD can usually be diagnosed clinically. If a definitive diagnosis is required, however, polysomnography is can be used.[29][30] PLMD is defined as a frequency of periodic limb movements of sleep (PLMS) >15/hour in adults, accompanied by sleep disturbance or daytime impairment.[7] Diagnosis of PLMD requires that PLMS are not due to other sleep disorders.[7]
Akathisia
SIGNS / SYMPTOMS
The desire to move often comes from mental or central discomfort or restlessness, not from uncomfortable sensations in the extremities. Symptoms do not tend to follow a circadian rhythm.
INVESTIGATIONS
No differentiating tests.
Peripheral neuropathy
SIGNS / SYMPTOMS
Small fiber peripheral neuropathy (as seen with diabetes, uremia, some inherited neuropathies and drugs) may mimic RLS.
Peripheral neuropathy has other symptoms not typically associated with RLS, such as numbness, paresthesias, and impaired balance or gait.
INVESTIGATIONS
Electromyogram and nerve conduction studies are normal in RLS.[1]
Nocturnal leg cramps
SIGNS / SYMPTOMS
Associated with muscle hardening, which is usually not present in RLS.
INVESTIGATIONS
No differentiating tests.
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