Currently, there is no single laboratory diagnostic test available for RLS. Therefore, the diagnosis is based entirely on an analysis of the patient’s symptoms. A few years ago, a group of physicians from North America,
Europe, and other parts of the world who had a special interest in RLS began an effort to develop some minimal clinical criteria for making a diagnosis of RLS. Development of such criteria, it was thought, would enable scientists to design good epidemiological studies for RLS and would standardize the definition of RLS for research purposes.
In 1995, the International Restless Legs Syndrome Study Group (IRLSSG) published four essential criteria for the diagnosis of RLS; these criteria were slightly modified in a later National Institutes of Health Consensus Conference and were published in 2003 in Sleep Medicine, an international sleep medical journal. These essential criteria are summarized in Table 2 and explained at length here. All four of the essential criteria must be met with or without the supportive and associated features (described below).
Four Essential Criteria for the Diagnosis of RLS
Criterion 1: an urge to move the legs, usually accompanied or caused by unpleasant or uncomfortable, sometimes indescribable sensations in the legs. Sometimes the urge to move is present without these uncomfortable sensations and, in some patients, the arms or other body parts are involved in addition to the legs.
Criterion 2: the urge to move or unpleasant sensations begin or worsen during periods of rest or inactivity such as lying down or sitting.
Criterion 3: the urge to move or unpleasant sensations are partially or totally relieved by movements such as walking or stretching, at least as long as the activity continues.
Criterion 4: the urge to move or unpleasant sensations are worse in the evening or at night than during the day or occur exclusively in the evening or at night. In case of long-standing and severe RLS, the worsening of symptoms at night may not be noticeable but must have been present previously.
Criterion 1: Individuals suffering from RLS develop an intense, disagreeable feeling, variously described as creeping, crawling, tingling, burning, painful, aching, cramping, viselike, or itchy, much like bugs crawling under the skin or water running under the skin.
The uncomfortable sensations occur mostly between the knees and ankles, causing an intense urge to move the legs to relieve these feelings. In some patients, the pain begins in the thighs or the feet. Sometimes patients complain of similar symptoms in the arms or other body parts (the hips, trunk, shoulders, genitals, anal regions, and, extremely rarely, the face).
The symptoms in the legs usually occur first and then the patient may complain of symptoms in other body parts later. Symptoms generally occur in both legs, but sometimes may occur in one leg or the symptoms may alternate between the two legs. About 20% to 25% of patients with RLS complain of actual pain. In some patients, especially in the early stages of the disease, the symptoms may occur occasionally, perhaps once a week. Later, as the disease progresses, symptoms may occur two to three times per week or even daily, and the intensity of the symptoms may also increase later in the course of the illness.
Criterion 2: Rest provokes symptom onset. RLS is a disease of quiescence. That is, when a patient is tired and trying to get to sleep, the symptoms begin and peak. At least in the beginning stages of the disease, the symptoms do not occur immediately on rest, but rather appear a few minutes after lying down or resting. As the disease progresses or if the patient develops what is called augmentation (see Questions 73 and 74), the latency between resting and the onset of symptom decreases or, in severe cases, symptoms appear immediately on lying down and the symptom intensity increases.
Criterion 3: Getting up from bed can immediately relieve the symptoms (at least partially) as long as the patient is up and moving and walking. Many patients try all types of tricks to obtain relief from the condition.
They move, massage, or rub their legs; they get out of bed to walk around. These maneuvers may temporarily relieve the symptoms. For some individuals, warm baths may prove helpful. In the most severe cases, symptoms may even occur in the daytime when patients are sitting or lying down.
Long travel by car, train, or plane may be particularly distressing. Many individuals with RLS find it impossible to sit for any length of time in a movie house or theater. They find that they must stand in the back of the theater to relieve the intense disagreeable feelings in their legs. Patients also find that distraction or intense mental activity (playing games, watching an exciting movie, engaging in a heated discussion) provides relief from the intense disagreeable feelings and the urge to move the legs.
Criterion 4: Most patients find that their symptoms are worse in the evening or during the night, or occur exclusively during these periods. In advanced cases with more progression of the disease, symptoms may occur toward the end of the day; symptoms may also be severe without any preferences for the evening period.
It is now conclusively established that RLS symptoms follow a true circadian (circa means “about,” dian means “day”) pattern, with the most severe symptoms occurring between 10 P.M. and 4 A.M. and often marked relief being noted between 7 A.M. and 11 A.M. This pattern persists even in individuals whose work schedule may include an unconventional sleep–wake cycle (e.g., shift workers).
The IRLSSG consensus conference also identified some supportive and associated features of RLS (Table 3)to help make a diagnosis in those cases where patients are not able to clearly describe their symptoms and because the physicians are not always certain whether symptoms fulfill all four of the essential criteria (see Table 2). With patients who do not fulfill all the essential criteria because of uncertainty about the symptoms or confusion of RLS symptoms with other conditions resembling RLS, the supportive clinical features listed in Table 3 may help in establishing a diagnosis.
As noted in Table 3, almost all patients with RLS respond to a dopaminergic medication, which is generally given in much smaller doses for RLS than for Parkinson’s disease. This response is initially positive but may not be universally maintained later on. For documenting periodic limb movements in sleep (PLMS) or periodic limb movements in wakefulness (PLMW) (see Question 34), an overnight physiological recording (polysomnographic recording; see Question 31) is needed. PLMS is present in at least 80% of RLS patients but not in 100%; thus it is not considered a specific diagnostic test for RLS. Approximately 60% of patients with RLS have a positive family history of RLS .
In a recent study performed at Johns Hopkins University, researchers demonstrated that up to 16% of individuals without RLS may satisfy all the four diagnostic criteria for RLS, giving rise to false positive cases. The RLS specialists, therefore, started a conversation about the possibility of adding another criterion to discriminate RLS from those conditions that closely mimic RLS.
Consensus has not yet been reached about which features differentiate these socalled mimetics from true RLS .