Clinically significant but unsuspected restless legs syndrome in patients with sleep apnea.

In this prospective study, the prevalence of clinically significant restless legs syndrome (RLS) with symptoms at least 2 to 3 days per week was 8.3% in 60 sequentially polysomnographically studied patients with clinically significant sleep apnea (Apnea Index score > 5 or Respiratory Disturbance Index score > 10). Age-matched spouses were used as a control group and showed a comparable prevalence of RLS at 2.5% (not significant). Although RLS appears to be only slightly more common in sleep apnea patients than in controls, the importance of this study lies in the fact that clinically significant RLS occurred in 1 of every 12 patients with sleep apnea and, in every case, the RLS was unsuspected before polysomnography. We recommend that all patients undergoing polysomnography to rule out sleep apnea be screened for the symptoms of RLS. We have found the MEMO-NIH consensus conference questionnaire administered at the time of polysomnography to be useful in this regard.