Toronto University.Canada: Up to 60 per cent of women experience chronic pain months after mastectomy. One in every three women undergoing a mastectomy could potentially be
spared chronic post-operative pain if anesthesiologists used a regional
anesthetic technique in combination with standard care, says Faraj Abdallah, an assistant professor in the department of anesthesia at the University of Toronto.
Standard care for mastectomies is a general anesthetic, whereby
anesthesiologists use gas to keep the patient asleep and narcotics to
control pain. Up to 60 per cent of women experience chronic pain three
months after they’ve had the surgery and at least half of those suffer
from this pain one year later.
“Sadly, the pain these women experience can be so severely debilitating
that it may require treatment by a pain specialist and pain killers,”
said Abdallah, who is also an anesthesiologist at St. Michael’s Hospital.
The regional anesthetic technique Abdallah added to standard care –
called ultrasound-guided paravertebral blocks – is similar to a dental
freeze. Trained anesthesiologists use a local anesthetic to freeze
nerves in the breast area.
Paravertebral blocks allow excellent pain control immediately after
surgery and help with long-term pain reduction, Abdallah said.
“Six months
after breast cancer surgery, we found that women who received
paravertebral blocks immediately before their mastectomies had more than
50 per cent lower risk of developing chronic pain compared to those who
received standard care,” said Abdallah.
The study, published in the journal PAIN,
showed that these nerve blocks most significantly reduced neuropathic
pain, which is the most common form of chronic pain affecting women
after mastectomies. Unlike the soreness and aching associated with
conventional pain – which may also affect these patients – neuropathic
pain also affects sensation.
“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,”
said Abdallah. “Grading pain on a scale of one to 10 fails to capture
neuropathic pain symptoms and frequently leads to under-diagnosis.”
Because each patient may experience different neuropathic symptoms
pain, Abdallah said clinicians needed a reliable tool to assess this
pain in women after breast cancer surgery and to measure how effective
their interventions are at preventing this pain.
In this same study, the researchers also showed that a pain assessment
test called the DN-4 can be used by clinicians to reliably identify
chronic neuropathic pain in women after breast cancer surgery.
The DN-4 combines interview questions with a physical assessment
performed by a clinician. It tests the patient’s sensation in the four
areas where post-mastectomy pain is likely to occur – the breast, the
chest, the shoulder and the arm.
“Breast cancer survival rates have improved significantly with advances
in diagnosis and management, but chronic pain management after breast
cancer surgery has not kept pace,” said Abdallah. “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.”
Abdallah began this randomized controlled trial while at Women’s
College Hospital. Since joining St. Michael’s Hospital, Abdallah has
continued this research and incorporated the paravertebral block
technique into his practice at the hospital.
Research was supported by a grant from the Ontario Ministry of Health
and Long Term Care’s Alternate Funding Plan Innovation Fund.
Geoff Koehler is a writer with St, Michael's Hospital, a partner of the University of Toronto.