The authors of a new study found that adding a technique called ultrasound-guided paravertebral blocks (PVB) to standard anesthesia care could help prevent chronic pain after the operation. In PVB, a local anesthetic like what is used in dentistry is used to “freeze” nerves in the breast area.
Also, these researchers tested the use of a pain assessment tool to help identify women who had chronic neuropathic pain after breast cancer surgery.
Dr. Faraj W. Abdallah, an anesthesiologist at St. Michael’s Hospital in Toronto, said in a press release, "Sadly, the pain these women experience can be so severely debilitating that it may require treatment by a pain specialist and pain killers.”
Joseph R. Holtman, MD, PhD, an anesthesiologist who specializes in pain management with Loyola Medicine in Chicago, told dailyRx News that PVB could represent an important development in pain management after breast cancer surgery.
"It certainly could be an important tool to help identify chronic neuropathic pain in post-mastectomy patients," Dr. Holtman said.
When a woman has breast cancer surgery, general anesthetics are administered to put her to sleep. After surgery, her pain is typically managed with narcotic pain medications. Dr. Abdallah’s team wanted to see if PVB added to routine care would relieve women’s pain immediately after surgery and prevent chronic pain later.
Women are typically asked to rate their pain on a scale of 1 to 10, with 10 being the most severe pain. However, this scale may not be specific enough to determine whether a woman has neuropathic pain. Neuropathic pain results from damage to the nervous system and can be caused by surgery.
Symptoms vary widely, according to Dr. Abdallah, who said, “One patient will lose sensation and not be able to feel a pin prick, another will experience severe pain if the skin is even lightly touched and the next patient may feel constant tingling or pins and needles. Grading pain on a scale of one to 10 fails to capture neuropathic pain symptoms and frequently leads to under-diagnosis."
Dr. Abdallah and team chose 66 women who were scheduled for breast surgery and divided them into two groups. All the women received general anesthesia and other routine care.
Half the women received PVB. The other half received what seemed like PVB to both patients and doctors but was really a placebo, or fake medication.
These researchers found that PVB decreased the risk of postsurgical chronic pain by half compared to women who received the placebo. PVB may also help provide effective pain reduction immediately after the surgery, according to Dr. Abdallah and colleagues.
Dr. Abdallah’s team also tested the DN-4, a series of very specific questions about pain. The DN-4 is a tool to help doctors assess chronic pain, but this was the first time it had been used to assess chronic pain after breast cancer surgery.
They found that the DN-4 was useful in identifying neuropathic pain in women who had had breast surgery.
"Proving that the DN-4 is a reliable test for this patient group is important because it gives clinicians a diagnostic tool to identify this pain, monitor its progress and measure the success of treatment," Dr. Abdallah said.
This study was published Feb. 25 in the journal PAIN.
A grant from the Ontario Ministry of Health and Long Term Care's Alternate Funding Plan Innovation Fund funded this research. Drs. Abdallah and Pamela J. Morgan received funding from the University of Toronto.
Study co-author Dr. Vincent W. Chan received equipment support from BK Medical Systems, Philips Medical Systems, SonoSite and Ultrasonix, which manufacture or distribute medical equipment.