Most people, for most surgical procedures, expect that there will be some post-surgery pain. Expecting pain, though, doesn’t really prepare a patient for experiencing it. Fortunately, the future of surgery may include less postoperative pain. A new technique developed at the University of Birmingham in England can, in advance of their surgery, identify patients likely to have severe postoperative pain.
The novel process enables physicians to consider using preventive pain medication during surgery. These patients are likely to experience less pain immediately after surgery, and are less likely to suffer chronic symptoms.
This pilot study demonstrates how electroencephalography (EEG) can be used to measure brain activity in patients about to undergo chest surgery (thoracotomy.) The brain’s alpha waves may predict a patient’s response to pain.
Preoperatively, the team measured the patients’ alpha waves — brain signals which usually oscillate between 8 and 14 Hz. Then, at least 72 hours after surgery, patients were asked to score their pain on a scale from 1-10. The findings clearly demonstrate a link between the patients’ alpha waves and their responses to pain. People whose alpha waves oscillated at less than 9 Hz were much more vulnerable to severe post-operative pain.
“The experience of being in pain is complicated and subjective, but it’s clear that these alpha waves are a reliable indicator of how severely an individual will experience pain,” explains study leader Dr. Ali Mazaheri, of the University of Birmingham’s Centre for Human Brain Health and School of Psychology, in a statement. “That offers clinicians a really valuable biomarker that they can use to prevent pain becoming an issue, rather than treating it after it has taken hold and becomes a serious, and potentially chronic problem.”
The study consisted of 16 patients about to undergo surgery to treat lung cancer. The patients’ alpha waves, measured before surgery, predicted with 100 percent accuracy which patients would report higher pain scores after surgery.
More work is required to elucidate the nature of the link between alpha waves and pain. The team thought it was related to pathways in the brain known to relay sensory messages from the thalamus, a structure in the brain which is a kind of relay station for sensory information. The thalamus also has a role in regulating alpha waves, reflecting the balance between pathways which signal pain and other pathways which suppress it.
“The alpha waves were really specific and accurate. Using this technique we can make real advances in pain management, not only in surgery, but in other treatments such as chemotherapy, enabling both clinicians and patients to make more informed choices,” says Fan Gao-Smith, a professor in anesthesia at Birmingham.
Adds Babu Nadu, an academic thoracic surgeon on the research team: “Chronic pain is relatively common for patients who experience severe acute pain after surgery. Current guidelines recommend antidepressants and acceptance therapy for people in this position. If we limit acute pain in the period directly following surgery, there is a real chance they won’t go on to develop chronic symptoms.”
The research is published in the British Journal of Anaesthesia.
