High prevalence of restless legs syndrome in somatoform pain disorder

Patients with somatoform pain often complain of sleep disorders, but sleep disorders are not an integrated part of the diagnosis of this disorder. Restless legs syndrome is associated with painful symptoms and sleep disturbances. The aim of our study was to evaluate the prevalence of restless legs syndrome (RLS) in somatoform pain disorder.

In this study 100 consecutive patients (mean age: 46.4; SD: 11.4; women: 58) diagnosed with somatoform pain disorder (SPD) were clinically investigated for the occurrence of RLS at the behavioral medicine clinic for pain outpatients in the department of psychiatry within the Medical University of Vienna. The pain parameters of SPD were assessed using a pain questionnaire and visual analogue scales (VAS). The severity of RLS was established using the questionnaire of the International Restless Legs Syndrome Study Group (IRLSSG).

The prevalence of restless legs syndrome found in somatoform pain disorder was 42%. Interrupted sleep was found in 83.3% in somatoform pain disorder with comorbid RLS and in 64.1% in somatoform pain disorder without RLS. Patients with continuous somatoform pain had a significant higher occurrence of RLS (Sample: 55%; with RLS: 71.4% and without RLS: 43.1%). The pain parameters increased parallel to the severity of RLS. Additionally, RLS was associated with higher psychosocial disability in family life.

The prevalence of RLS is high in our sample of patients with somatoform pain disorder. There seems to be a difference in pain profile between patients with and without RLS. RLS may increase the pain level and prolong pain in somatoform pain disorder. RLS should be considered when a somatoform pain disorder is diagnosed.