TABLE 1

Diagnostic criteria for restless legs syndrome (RLS)

Essential clinical criteria
 An urge to move the legs, usually but not always accompanied by or felt to be caused by uncomfortable and unpleasant sensations in the legsSometimes the urge to move the legs is present without the uncomfortable sensations. The arms or other parts of the body may also be involved in addition to the legs. Often the urge to move and the accompanying sensory symptoms are difficult to separate symptomatically or temporally. The sensations are described as painful in one-third of RLS patients.
 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 sittingWhen examined by means of objective tests, such as the multiple SIT, patients with RLS report pronounced sensory symptoms in the legs and the presence of PLMS while both resting and awake, and these increase with the duration of rest.
 The urge to move the legs and any accompanying unpleasant sensations are partially or totally relieved by movement, such as walking or stretching, at least as long as the activity continuesRLS patients feel at least some symptomatic relief right after the initiation of the activity. Usually, the simple act of moving or walking suffices. Symptoms should generally not return nor worsen as long as 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 dayPatients with RLS should report fewer symptoms when resting in the morning than in the evening or night. The critical clinical question for this criterion involves ascertaining circadian differences in symptom response to rest. However, patients with very severe RLS may have relentless symptoms persisting throughout the day and night.
 The occurrence of the above features is not solely accounted for by symptoms primary to another medical or behavioural condition (e.g. myalgia, venous stasis, leg oedema, arthritis, leg cramps, positional discomfort or habitual foot tapping)These conditions, often referred to as “RLS mimics”, have been commonly confused with RLS.
Supporting featuresThese criteria are not essential, but can help to support the diagnosis.
 Periodic leg movementsPeriodic leg movements are repetitive, stereotyped flexor- withdrawal-like movements of the legs which occur during sleep. However, periodic leg movements can also occur during wakefulness. PLMS occur in ∼80–89% of RLS patients seen in a clinic setting, and periodic limb movements during wakefulness occur with a similar same range of periodicity. Periodic leg movements occur with significant transient changes in EEG, heart rate and blood pressure, which may reflect an underlying process that produces an increased risk of cardiovascular disease which has been observed in RLS patients in several studies.
Although PLMS are fairly specific to RLS, they are not very sensitive, as they do occur at lower rates with several other medical conditions, with many medications and are common among adults aged >45 years
Periodic limb movement disorder is a sleep disorder characterised by an increased number of PLMS associated with insomnia, unrefreshing sleep or daytime hypersomnia after exclusion of other sleep disorders as a cause of these symptoms.
In contrast, periodic leg movements during relaxed wakefulness, as measured by the SIT, have high sensitivity and specificity for RLS, particularly if evaluated multiple times and combined with subjective leg discomfort scores in the multiple SIT.
 Dopaminergic treatment responseMost RLS patients show at least some initial clinical benefit to fast-acting dopaminergic medications, e.g. levodopa and dopamine agonists. Although a failure to respond to dopaminergic treatment should raise some concern about the accuracy of diagnosis, it does not necessarily exclude a diagnosis of RLS.
 Family historyRLS has been noted to occur commonly in families, indicating significant genetic or shared environmental factors for the disease. In fact, the risk of RLS is nearly six times higher among first-degree relatives of RLS patients than among those without.
 Lack of profound daytime sleepinessPatients with moderate-to-severe RLS have chronic short sleep times, but generally do not report a level of daytime sleepiness that would be expected for the degree of sleep loss. They will usually have slightly elevated but still normal ESS scores. Thus, hyperarousal might be part of the pathophysiology of RLS. Profound sleepiness should prompt evaluation for another cause, such as sleep apnoea, narcolepsy or medication effect.

SIT: suggested immobilisation test; PLMS: periodic leg movements of sleep; EEG: electroencephalogram; ESS: Epworth sleepiness scale. Reproduced and modified from [9] with permission.