The Effects of Transcranial Electrostimulation (TES) on Postoperative Pain and Functional Patient Outcomes After Surgery for Obstructive Sleep Apnea Syndrome

The incidence and severity of postoperative pain in patients undergoing major airway surgery for OSA, such as palatopharyngoplasty (PPP) and maxillomandibular advancement (MMA) is high, and may persist for days, significantly contributing to patient's morbidity. High doses of intravenous and oral opioids are frequently required to achieve adequate pain relief. Yet, the increased sensitivity of OSA patients to opioid analgesics, and associated high risk of postoperative respiratory depression and upper airway obstruction limit the traditional therapeutic options, frequently making pain control after PPP and MMA surgery suboptimal.

The effect of significant postoperative pain on surgical outcomes is multifold. Poorly controlled post-surgical pain increases patient morbidity, impairs wound healing, and negatively affects patient recovery and functional outcomes, such as ambulation, a resumption of a normal oral intake, a return to normal daily activities, a return to work, and others. Side effects of opioid medications, such as urinary retention, constipation, nausea, vomiting, dizziness, and itching may further adversely affect recovery and cause patient dissatisfaction with the surgical procedure.

The development of the new, effective analgesic modalities, is therefore highly desirable for OSA surgical patients, and particularly those undergoing PPP and MMA surgeries. Transcranial electrostimulation (TES) is a non-invasive brain stimulation technique that employs administration of a weak electrical current (≤ 5 mA) through the electrodes positioned on the skin of the patient's head. TES is a safe procedure, with a low risk of associated, minor side effects It is widely believed that TES with combined direct (DC) and alternating (AC) current (TES DC:AC) triggers the release of endogenous opioids and other central neurotransmitters (e.g. norepinephrine) that interrupt nociceptive processing. The investigator's previous studies have demonstrated that TES DC:AC produces quickly evolving, effective non-pharmacological analgesia, without associated respiratory depression or other opioid-induced side effects. If analgesic effect of TES can be demonstrated in this study, the TES may become an attractive adjunct for postoperative analgesic treatment for OSA patients, allowing for improved quality of analgesia and enhanced recovery.

Moreover, demonstrating TES analgesic effect may facilitate its widespread use as a non-pharmacological analgesic adjunct postoperatively, especially in elderly patients, who have a high incidence of associated OSA and sensitivity to systemic opioids. The incidence of OSA in general surgical population reaches over 20%.