Chronic post-surgical pain (CPSP)

Symptoms of chronic post-surgical pain

CPSP often feels different from ordinary healing pain. As well as ongoing pain around your surgical scar or the wider operated area, you might notice:

• allodynia, where things that shouldn't hurt, like light touch or clothing, become painful
• hyperalgesia, where things that are mildly painful feel much more painful than expected
• tingling or numbness around the scar
• unusual sensitivity or swelling, or a burning or stabbing quality to the pain.

Some people also notice their pain feels unusually sensitive to cold within the first couple of weeks after surgery. This can be an early sign that the pain is becoming persistent rather than settling as expected, so it's worth mentioning to your surgical team.

Causes and risk factors

CPSP happens when nerves are affected by an operation, either through direct injury, inflammation, or ongoing changes in how your nervous system processes pain signals, sometimes called sensitisation.

Not everyone with nerve damage during surgery goes on to develop CPSP, and not everyone with CPSP has clear nerve damage, so why it develops in one person and not another isn't fully understood.

Factors before your operation that raise your risk include:

• pain in the area before your operation, or another long-term pain condition such as headaches
• having had surgery before or needing repeat surgery
• being a younger adult or, for some procedures, being female
• anxiety, depression or a tendency to worry intensely about pain
• smoking, obesity or taking opioid painkillers before your operation.

Factors during and after your operation also matter:

• the type of surgery – amputation, thoracotomy (chest surgery) and breast surgery carry some of the highest risk
• surgery lasting longer than 3 hours, or involving major body cavities, large joints or deep tissue
• more severe or longer-lasting pain in the days after your operation
• complications such as infection or bleeding after surgery.

Types of chronic post-surgical pain

CPSP is often named after the operation that caused it. You might hear terms such as post-thoracotomy pain syndrome (after chest surgery), post-mastectomy pain syndrome (after breast surgery), or phantom limb pain (after an amputation), among others.

Doctors also distinguish between two broad qualities of pain, which often overlap:

• Nociceptive pain: This comes from ongoing tissue damage or inflammation
• Neuropathic pain: This comes from the nerves themselves being affected, and tends to include the tingling, numbness or allodynia described above. Around 30% of people with CPSP have a neuropathic component to their pain, though this varies depending on the type of surgery.

Diagnosing chronic post-surgical pain

There's no single test for CPSP. Instead, doctors diagnose it by checking that your symptoms fit a specific pattern:

• Your pain started, or got worse, after a surgical procedure
• It has lasted at least 3 months and is significantly affecting your quality of life
• It's located at or near the surgical site, or follows the path of a nerve running through that area
• Other possible causes, such as infection or a return of the original condition, have been ruled out.

Your doctor will also ask about the pattern and quality of your pain, since features like allodynia or tingling can point towards a neuropathic component, which may respond to different treatments than pain from ongoing tissue inflammation alone.

Treatment for chronic post-surgical pain

There's no single treatment that works for everyone with CPSP, and care usually works best when it combines several approaches from a team that might include your surgeon, an anaesthetist or pain specialist, a physiotherapist and a psychologist.

Medicines are often similar to those used for other types of nerve pain, and may include:

• anticonvulsant medicines such as gabapentin or pregabalin
• certain antidepressants, which can also help with nerve-related pain
• topical treatments applied directly to the skin, such as lidocaine or capsaicin
• paracetamol, anti-inflammatory painkillers or weak opioids for milder pain, with strong opioids used cautiously and only when necessary.

If medicines alone don't help enough, other options include nerve blocks and injections or, in specific cases, procedures such as pulsed radiofrequency treatment or a nerve stimulator, which aim to interrupt or calm the pain signals from the affected nerve.

Physiotherapy, cognitive behavioural therapy (CBT) and other psychological support are also valuable, helping you manage the impact of pain on daily life even where the pain itself can't be fully resolved.

In a small number of cases, if other treatments haven't worked, surgery may be considered. This might involve removing a painful nerve growth, called a neuroma, and allowing the nerve to retract into surrounding muscle, or repositioning an affected nerve. Surgery is generally a later option used once other treatments have been tried, since it carries its own risk of triggering further chronic pain.

When to see a doctor

Speak to your GP, surgeon or the pain team involved in your surgery if pain around your operation site hasn't settled after a few months, is getting worse rather than better, or is starting to affect your sleep, mood or daily activities. The sooner ongoing pain is recognised and addressed, the better your chances of managing it well.

Contact your surgical team promptly if you develop new swelling, redness, a fever or discharge from your wound, since these can be signs of infection rather than CPSP and need urgent assessment.