Restless legs syndrome (RLS) is a neurologic movement disorder of the limbs that is often associated with a sleep complaint. Patients with RLS may report sensations, such as an almost irresistible urge to move the legs, that are not painful but are distinctly bothersome. RLS can lead to significant physical and emotional disability.
Signs and symptoms
Diagnostic criteria from the International RLS Study Group (IRLSSG) are as follows:
An urge to move the legs usually but not always accompanied by or felt to be caused by uncomfortable and unpleasant sensations in the legs.
The urge to move the legs and any accompanying unpleasant sensations begin or worsen during periods of rest or inactivity such as lying down or sitting.
The urge to move the legs and any accompanying unpleasant sensations are paritally or totally relieved by movement, such as walking or stretching, at least as long as the activity continues.
The urge to move the legs and any accompanying unpleasant sensations during rest or inactivity only occur or are worse in the evening or night than during the day.
The occurrence of the preceding features are not soley accounted for as symptoms primary to another medical or behavioral condition such as myalgia, venous stasis, leg edema, arthritis, leg cramps, positional discomfort, or habitual foot tapping.
Approximately 85% of patients with RLS have periodic movements of sleep, usually involving the legs (periodic leg movements of sleep [PLMS]).
PLMS is characterized by involuntary, forceful dorsiflexion of the foot lasting 0.5-5 seconds and occurring every 20-40 seconds throughout sleep.
Other features commonly associated with RLS but not required for diagnosis include the following:
Involuntary, repetitive, periodic, jerking limb movements: Either during sleep or while awake and at rest
See Presentation for more detail.
All patients with symptoms of RLS should be tested for iron deficiency.
At a minimum, a ferritin level should be obtained, although a complete iron panel, including the following, is preferable, since ferritin can be falsely elevated in acute inflammatory states:
Total iron binding capacity
If a secondary cause of RLS is suspected on the basis of history, abnormal findings on neurologic examination, or poor response to treatment, other laboratory tests should be done. These include a complete blood count (CBC) and measurement of levels of the following:
Blood urea nitrogen (BUN)
Fasting blood glucose
Thyroid-stimulating hormone (TSH)
Other studies include the following:
Needle electromyography and nerve conduction studies: Should be considered if polyneuropathy or radiculopathy is suspected on clinical grounds, even if the results of the neurologic examination are apparently normal
Polysomnography: May be necessary to quantify PLMS or to characterize sleep architecture, especially in children and in patients who continue to have significant sleep disturbances despite relief of RLS symptoms with treatment
See Workup for more detail.
Drug therapy for primary RLS is largely symptomatic, since cure is possible only in secondary disease. Medications used in the treatment of RLS include the following:
Presynaptic alpha2-adrenergic agonists
Sleep hygiene measures
Avoidance of caffeine, alcohol, and nicotine in patients with mild RLS who are sensitive to these substances
Discontinuation, when possible, of medications that cause or exacerbate RLS, such as selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinepherine reuptake inhibitors (SNRIs), diphenhydramine, and dopamine antagonists
Physical modalities before bedtime, such as a hot or cold bath, whirlpool bath, limb massage, and vibratory or electrical stimulation of the feet and toes