Symptoms of Restless Legs Syndrome

Like adults, children with RLS seek relief of discomfort by moving their legs, fidgeting, stretching, walking, running, rocking, or changing positions. In the classroom, this may be viewed as inattentiveness, hyperactivity, or disruptive behavior. The RLS discomfort is typically described with age-appropriate but nonspecific terms such as “oowies,” “boo-boos,” “tickle,” “bugs,” “spiders,” “ants,” “static,” and “a lot of energy in my legs.” Sleep disturbance is common in both children and adults with RLS. In some children, the sleep disturbance may precede or overshadow the complaint of typical RLS leg discomfort.^9,12 Often, sleep quantity and quality are affected with resultant consequences on daytime function.

Periodic Limb Movement Disorder

Periodic limb movements in sleep (PLMS) are characterized by brief jerks during sleep (lasting 0.5 to 5.0 seconds), which typically occur at 20- to 40-second intervals.^13,14 PLMS are more common in the toes, feet, and legs, than in the arms. The affected individual is usually not aware of the movements or of the associated transient arousals that disrupt sleep continuity. Between 80% and 90% of adults with RLS have PLMS.¹⁵ In healthy children and even young adults, PLMS rarely exceed five per hour.^16–18 Thus, the presence of PLMS of more than five per hour in children or adolescents supports a diagnosis of RLS (see later).¹⁹ PLMS, however, are not specific to RLS but also can be seen in some other sleep disorders and can be induced or aggravated by certain medications (particularly antidepressant medications).^14,20 PLMD is diagnosed when there are (1) PLMS exceeding norms for age (>5 per hour for children), (2) clinical sleep disturbance, and (3) the absence of another primary sleep disorder or reason for the PLMS.¹⁴ In some children, a diagnosis of PLMD will evolve over time to a diagnosis of “RLS with PLMS” as the typical RLS feelings develop.

Diagnostic Criteria

Special criteria for the diagnosis of RLS were established for children at a National Institutes of Health (NIH) consensus conference on RLS.¹⁹ These criteria for childhood RLS should be used up to and including the age of 12 years, after which the adult criteria should be used. Several issues led to the development of separate criteria, which include (1) young children may have difficulty in describing the RLS feelings, (2) clinical experience indicates that children may report the RLS discomfort more during the day than at night or may not be able to determine when it is worse, and (3) a family history of RLS in a first-degree relative is likely relevant if a child meets some, but not all, of the adult criteria for RLS. However, the criteria for definite RLS were constructed as more difficult to fulfill than the criteria for adults because of a desire that false-positive diagnoses be avoided. Children can be diagnosed with definite RLS in either of two ways, as described in the table below (Table 22-1). Criteria for probable RLS and possible RLS were developed for research purposes (Tables 22-2 and 22-3).

TABLE 22-1 Criteria for the Diagnosis of Definite RLS in Children

TABLE 22-2 Criteria for the Diagnosis of Probable RLS in Children

TABLE 22-3 Criteria for the Diagnosis for Possible RLS in Children

Source: The NIH RLS workshop. RLS: Diagnosis and Diagnostic and Epidemiological Tools (2003).¹⁹

Prevalence, Impact, and Relationship to “Growing Pains”

A large epidemiological study applied the NIH workshop diagnostic criteria to a population-based questionnaire survey of families with children in the United States and the United Kingdom.¹⁰ Definite RLS criteria were met by 1.9% and 2% of all children ages 8 to 11 and 12 to 17 years, respectively. RLS occurring = 2/week and causing moderate to severe distress when present had been identified by a panel of experts as indicating clinically significant RLS for adults, likely to benefit from treatment.^21,22 In the pediatric study, 0.5% of children ages 8 to 11 years and 1.0% of those ages 12 to 17 years reported symptoms meeting these criteria for clinically significant RLS. There were no significant gender differences. A family history of RLS was common, with 70% of all children diagnosed with definite RLS having a biological parent who reported symptoms consistent with a diagnosis of RLS, including 16% for whom both parents had RLS symptoms. The children with definite RLS symptoms, compared with the non-RLS children, more commonly reported sleep disturbance (69% versus 40%, p <.001). In addition, children with clinically significant RLS reported a high rate of adverse consequences from the RLS symptoms, such as negative mood (59% to 68%), decreased energy (51% to 59%), and inability to concentrate on school work (41% to 45%) (Fig. 21-1).

FIGURE 22-1. Perceived consequences of restless legs syndrome (RLS) for children and adolescents with moderate-severe RLS symptoms.

Reprinted with permission from Picchietti D, Allen RP, Walters AS, et al. Restless legs syndrome: prevalence and impact in children and adolescents—The Peds REST study. Pediatrics 2007;120:253-266.

Six other studies have reported pediatric-onset RLS prevalence data and one has reported pediatric PLMD prevalence data. A study of 1084 unselected children from 12 pediatric practices found RLS to affect 1.3%.²³