Study objectives: We hypothesized that the upper airway resistance syndrome (UARS), the component event being a respiratory effort related arousal (RERA), and periodic limb movements in sleep (PLMS), the component event being repetitive, stereotyped extremity movements occurring in a periodic fashion, were associated in certain patients.
Design: Invasive polysomnography using Pes and full facemask pneumotachography was used to identify RERA's in patients. Periodic limb movements (PLM) were scored according to standard criteria and as associated with RERA if the movement occurred between the Pes nadir and the onset of the arousal.
Setting: A university hospital Sleep Disorders Laboratory.
Participants: Patients consecutively diagnosed with PLMS in our sleep disorders laboratory over a 1 year period.
Interventions: None.
Measurements and results: Fourteen of twenty patients demonstrated UARS in addition to PLMS (70%). In those 14, 63% of RERAs were associated with a PLM (mean = 51.7 + 36.2 PLM/RERAs per study vs 5.6 + 6.3 PLM/RERAs per study if the association were random). Patients with UARS had more arousals with their PLMs (P = 0.0006).
Conclusions: An association exists between PLMS and UARS on both a group level and an event level. A high percentage of PLM with arousals correlated with breathing events due to increased effort in UARS; this may be of clinical utility in the management of PLMS patients.