Effects of preconditioning of electro-acupuncture on postoperative cognitive dysfunction in elderly: A prospective, randomized, controlled trial

Postoperative cognitive dysfunction (POCD) is a common neurological complication in elderly patients, characterized by problems with memory, concentration, anxiety, and personality changes after surgical procedures. Its incidence ranges from 20% to 79% in cardiac surgery and from 4.1% to 22.3% in non-cardiac surgery, representing a significant physical, psychological, and economic burden for patients and families. Electroacupuncture has emerged as a promising therapeutic technique that combines the traditional principles of acupuncture with low-frequency electrical stimulation.

This prospective, randomized, controlled trial evaluated 90 elderly patients (>65 years) undergoing spine surgery between October 2016 and April 2017. Participants were randomized into two groups: control (n=45) and electroacupuncture (n=45). The EA group received treatment at the Baihui (GV-20), Dazhui (GV-14), and Zusanli (ST-36) points for 30 minutes before anesthesia, using sparse-dense wave stimulation (2/15 Hz) with an intensity of 1 mA. The choice of these points was based on traditional Chinese medicine, where Baihui and Dazhui belong to the Du meridian and are closely related to brain function, while Zusanli is an important point for general health care.

Cognitive assessment was performed using the Mini-Mental State Examination (MMSE) at three time points: one day before surgery, and 7 and 30 days after the procedure. Blood samples were collected for analysis of inflammatory markers (IL-6, IL-10) and brain injury (S100b) at different time points: before treatment, one hour after surgical incision, and at the end of surgery. The anesthetic protocol was standardized for both groups, with induction using sufentanil, midazolam, etomidate, and cisatracurium, and maintenance with propofol and remifentanil.

The results demonstrated significant benefits of electroacupuncture preconditioning. In the EA group, MMSE scores remained stable at 7 and 30 days postoperatively, while in the control group there was a significant reduction at 7 days (p=0.023). Inflammatory markers IL-6 and IL-10, as well as S100b protein (indicator of brain injury), showed significantly lower levels in the EA group one hour after incision and at the end of surgery. Additionally, the EA group required significantly lower doses of remifentanil (p=0.031) and propofol (p=0.009) during the procedure.

The proposed mechanisms for these beneficial effects include reduction of the inflammatory response and brain injury. IL-6, produced by mononuclear macrophages, is a key pro-inflammatory factor in acute trauma, while IL-10 has anti-inflammatory properties. S100b protein, expressed mainly in astrocytes and Schwann cells, is considered a reliable marker of brain injury, with elevated concentrations being toxic to neurons and associated with POCD.

Limitations of the study include the relatively small sample size and the restriction to elderly patients undergoing spine surgery specifically. Future studies are needed to evaluate the efficacy of this intervention in other age groups and types of surgery. The findings suggest that electroacupuncture preconditioning represents a promising, safe, and noninvasive strategy for the prevention of postoperative cognitive dysfunction in the elderly, offering additional benefits such as reduction of anesthetic consumption and modulation of the inflammatory response.