Binaural beat stimulation as a tool to reduce preoperative anxiety in patients undergoing elective surgery and general anesthesia - results from a randomized controlled trial.

Pronounced anxiety is increasing in society and is common in patients awaiting surgery. It's associated with increased anesthetic requirements, increased postsurgical pain, and also adverse postoperative outcomes. Binaural beats have been proposed as a non-pharmacological intervention to reduce anxiety in medical settings. We collected information about the levels of anxiety using the State-Trait Operation Anxiety (STOA) questionnaire. Preoperatively, patients either received binaural beat stimulation (=Binaural Beat) or not (=Control). During the stimulation, we recorded multichannel electroencephalogram (EEG), from which we derived power, morphology, and connectivity measures of the alpha band (phase lock values, coherence). We used estimation statistics to compare anxiety levels. To quantify the effect of the binaural beat intervention on EEG features, we analyzed variance and the area under the receiver operating curve statistics. Compared to the control group, relative change in STOA-S was, on average, 6 [12.2, 1] percentage points higher in the binaural beat group (p=0.045). State anxiety scores dropped by 1.4 points [-2.3, -0.7] (p=0.003) in the control group and by 2.7 [-3.9, -1.7] (p=0.001) in the binaural beat group. Group assignment did not affect alpha power (ges=0.01, p=0.456), while there may be some effect on alpha band coherence (ges=0.03,p=0.054) and phase locking (ges=0.04, p=0.037). There is evidence that a musical intervention, as well as simple relaxation before surgery, can reduce preoperative anxiety in patients awaiting surgeryAs only a few electrodes or electrode combinations differed between the groups, some regions might be more prone to align with external stimuli. Future studies should include other types of musical interventions (e.g. monoaural beats) in order to fully understand the role of binaural beats and their potential to reduce anxiety beyond the mere presentation of music.