Original articleRestless legs syndrome: diagnostic criteria, special considerations, and epidemiology: A report from the restless legs syndrome diagnosis and epidemiology workshop at the National Institutes of Health
Introduction
In 1945, the Swedish neurologist Ekbom described a condition that he named restless legs syndrome(RLS) [1]. A half-century later, the newly formed International RLS Study Group (IRLSSG) proposed and published a set of criteria to allow for a more-uniform diagnosis of this sensorimotor disorder that often profoundly disturbs sleep [2]. Since the publication of the IRLSSG criteria, research has revealed that RLS is common and treatable, yet underdiagnosed [3], [4], [5], [6], with a wide variation in severity of symptoms. The body of literature on RLS has grown exponentially, mainly reporting clinical research. Recent animal and molecular studies have also begun to elucidate the still-uncertain nature of the basic pathophysiology of RLS [7].
Because of the great quantity of newly published information about RLS and the increased amount of clinical experience with the disorder, the RLS Foundation and the National Institute on Aging, in partnership with the National Center on Sleep Disorders Research, the National Institute of Neurological Disorders and Stroke, the National Institute of Mental Health, the National Institute of Nursing Research, and the National Institute of Child Health and Human Development, held an RLS diagnosis and epidemiology workshop to readdress the diagnostic criteria on May 1–3, 2002, at the National Institutes of Health. Members of the IRLSSG were invited to attend and supported this meeting.
The workshop brought together RLS experts, as well as authorities on epidemiology and the design of questionnaires and scales. The diagnostic criteria were discussed thoroughly at the workshop and in subsequent exchanges. The diagnostic criteria were updated and rephrased to both incorporate new scientific knowledge about RLS and better express the criteria to reflect the actual working interpretation of them as used by clinical experts in the field. Members of the IRLSSG reviewed the revised criteria and accompanying explanatory material, and the acting executive committee of the IRLSSG also approved the final formulation of the new RLS diagnostic criteria.
In addition to readdressing the previously proposed criteria, the workshop participants also focused on developing new diagnostic criteria for two special populations – the cognitively impaired elderly and children. These groups were selected for special attention because of the difficulty encountered in eliciting from them verbal confirmation of the subjective symptoms of RLS. Because the phenomenon of augmentation in people with RLS who receive pharmacologic treatment is so common, workshop participants also developed specific criteria for the diagnosis of augmentation. Finally, given the update on the diagnostic criteria, this conference also included a working group to review the methods for epidemiologic studies and to propose standardization of these studies that would incorporate the newer diagnostic criteria. Thus, this report is divided into the following four sections: diagnostic criteria for RLS, diagnostic criteria for RLS in special populations, diagnostic criteria for RLS augmentation, and assessment of RLS in epidemiologic studies.
Section snippets
Diagnostic criteria for RLS
Restless legs syndrome is a sensorimotor disorder that often has a profound impact on sleep [2]. The severity of the symptoms varies widely, ranging from occurring only occasionally in a stressful situation to nightly and severe, with almost total disruption of sleep. An RLS severity rating scale has been developed by the IRLSSG to evaluate this wide range of symptom severity [8]. The workshop participants, in collaboration with members of the IRLSSG, determined that the following four
Diagnostic criteria for RLS in special populations
In addition to developing standard criteria for RLS in adults, the workshop participants also identified special populations for whom diagnostic criteria do not currently exist. These special populations include cognitively impaired older adults and children and adolescents. Because evidence to support the diagnostic criteria in these populations is less than that for the general adult population, these recommendations are based predominantly on the consensus of expert opinion. In circumstances
Diagnostic criteria for augmentation of RLS
At the workshop, criteria for a common definition of augmentation in RLS were agreed upon. First described in 1996 [119], augmentation has been found to be a common complication of treatment for RLS with dopaminergic therapies [4], [119], [120], [121], [122], [123], [124], [125], [126], [127], [128]. A MEDLINE search performed on May 23, 2002, using the key words restless legs and augmentation produced 10 articles [4], [119], [120], [121], [122], [123], [124], [125], [126], [127], of which five
Assessment of RLS in epidemiology studies
Population-based epidemiologic investigations can complement knowledge gained in laboratory and clinical settings by providing precise estimates of disease prevalence and incidence. They can also generate and test etiologic hypotheses through the analysis of risk factors in cases and controls sampled from the same source population. To date, population-based studies of RLS are few in number, limited in size, and restricted in geographic scope and use inconsistent ascertainment tools. From six
Conclusion
These revised diagnostic criteria for RLS have been developed to replace the previously proposed criteria and to extend the new criteria to the special populations of cognitively impaired elderly, children and adolescents, and patients who develop the phenomenon known as augmentation. Those individuals who have been involved in the reassessment process conclude that these revised criteria incorporate the new scientific knowledge gained about RLS and also clarify the concepts in the prior
Acknowledgements
We wish to thank Pharmacia Corporation for their generous unrestricted grant to the Restless Legs Syndrome Foundation to provide part of the support for this workshop and the staff of the National Institute on Aging and the National Center on Sleep Disorders Research for their help in planning and conducting this workshop. We wish to thank the Restless Legs Syndrome Foundation for their efforts in organizing this workshop and to the RLS Foundation staff, particularly the Executive Director,
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