targeting different pain key to improving treatment

Nerve pain

Until recently, no research had looked into whether people with endometriosis actually have neuropathic pain. But there are a couple of theories why sufferers can experience this kind of pain.

First, the bits of tissue which begin growing outside the uterus – called “endometriotic lesions” – have new nerves inside them. These new nerves could be more sensitive, or they could be being squashed by other tissue, both of which can cause neuropathic pain.

Second, the only definitive way to diagnose endometriosis is through laparoscopy (where a small camera is inserted into the pelvis through a small incision in the belly button). This naturally involves cutting through nerves, which can lead to post-surgical neuropathic pain.

We carried out an online survey of 1,417 people who had reported having endometriosis that had been diagnosed by laparoscopic surgery. We used a screening tool for neuropathic pain called painDETECT, which is made up of nine questions that ask about the characteristics of pain – such as whether the pain is “burning” or “like electric shocks”. It also asks about how the pain varies over time and whether it radiates to other areas of the body. Depending on the answers the person provided, we were able to categorise people into having either nociceptive pain or neuropathic pain – or a mixture of both.

We found that 40% of respondents had neuropathic pain. A further 35% had a mixture of neuropathic and nociceptive pain. We also found that those with neuropathic pain experience greater pain in general (both during their period, throughout their menstrual cycle or during sex), greater anxiety and depression, and greater fatigue and cognitive dysfunction (such as having trouble thinking and remembering things).

We also found that the greater the number of endometriosis or other abdominal surgeries a person had had, the more likely they were to have neuropathic pain. Surgery is not only used to diagnose endometriosis, but to cut or burn away endometriotic lesions in the hope of relieving symptoms.