Methods using preventive analgesia to treat pain after surgery before it develops

York University Professor Joel Katz is studying methods of preventing or significantly reducing pain after surgery by employing preemptive or preventive analgesia to treat pain before it develops.

“Basically, we are trying to block surgically-induced noxious signals that can cause a state of central nervous system hypersensitivity in the spinal cord,” says Katz, “We do this by administering analgesic drugs via the epidural route before surgery.” He distinguishes between preemptive analgesia that involves pre-operative treatment only and preventive analgesia which is a broader concept.

“Chronic post-surgical pain is a tremendous problem,” says Katz, York’s Canada Research Chair in Health Psychology, “Many patients experience pain long after they are supposed to have healed.”

Katz says studies show that injuries, including surgical procedures, can cause a state of central nervous system hypersensitivity that leads to a heightened experience of pain and even pain arising from a stimulus that normally is not painful.

“A common example of pain in response to a normally non-painful stimulus occurs after sunburn,” says Katz, “where a gentle pat on the shoulder or a warm shower can provoke a powerful pain response.” Katz adds that the phenomenon of central nervous system hypersensitivity has only relatively recently been shown to contribute to post-operative pain.

Currently, Katz notes, about one quarter of patients who are seen at specialty pain clinics are referred because of chronic post-surgical pain problems. He says that 80 per cent of amputees experience chronic ‘phantom limb’ pain years after amputation, while 30 per cent to 50 per cent of chest surgery patients report chronic post-surgical pain more than one year after the operation. Even a relatively minor procedure such as a hernia repair has a significant incidence of chronic post-surgical pain. Almost 30 per cent per cent of hernia patients report pain one year after surgery, although this number drops to nine per cent after five years.

Recent studies by Katz and his colleagues at the University Health Network in Toronto have demonstrated that patients who have preemptive or preventive pain control show significantly less intense post-surgical pain. In one study pain disability was reduced three weeks after surgery. “The beneficial effect is no longer apparent after six months,” says Katz, “but this approach leads to less pain in the days immediately after surgery which may help patients recover more quickly when they leave the hospital and return home.” He hopes this research will ultimately provide major benefits both for patients and the entire healthcare community.