Pain, differential diagnosis and avoiding the wrong rabbit hole

The idea that a patient’s pain is always trying to tell us something is an increasingly outdated notion.

These days, pain researchers — and much of the medical community — accept that pain can be a disease in its own right; and is not always justified by something physical.

As multi-award winning clinical consultant pharmacist and pain management educator Joyce McSwan puts it, “Pain is meant to serve a function — to alert us to keep away from its trigger. But sometimes our pain response can become dysregulated and out of proportion.

“The communication pathways in our body can become overprotective and tell us that a stimulus is harmful when it may not be,” she said.

In fact, McSwan — who is also the founder of PainWise — estimates that this misfiring of the body’s pain response accounts for around 40–50% of chronic pain cases.

She says events, like moving furniture, can cause a severe pain reaction in people living with chronic lower back pain, even if an injury did not occur.

“It can be debilitating and the patient can be convinced they have torn something — but nothing is coming up in imaging, and there are no other physical red flags, like signs of numbness or weakness of legs.

“In this case, it is likely due to musculoskeletal or nerve sensitivity that has caused the pain flare-up. It could also be a limbic response — a psychological trigger or somatic memory of a former injury or combination of both,” she said.

McSwan also says that pain is complex, meaning it can be challenging for healthcare workers to distinguish between pain with a physical cause, and a dysregulated sensitised pain response. Especially when the two can co-occur.

“The lines can become blurred and it is challenging for both clinician and patient to decipher what is going on,” she said.

“Likewise, you could have someone with a chronic disease like arthritis, who has also gained weight and become more sedentary, with mental health implications. Even the slightest of movement can set off a severe pain response in this individual — and that response can be disproportionate to the arthritic pain they previously lived with.”

Develop multidisciplinary pain expertise

To handle pain cases appropriately, McSwan says clinicians need to understand pain as an area of study “really well”.

“If you aren’t confident doing differential diagnosis for pain, you can easily go down the wrong rabbit hole and offer patients the wrong advice and treatment.

“Understanding the relationship between pain and lifestyle factors like smoking, weight gain and even a person’s gait keeps it holistic,” she said.

Next, the clinician should get to know the patient’s history intimately, she recommended.

“Once upon a time, they may have had an acute fall. Then, other insidious episodes might have made it more sensitive.

“Now, the patient avoids moving because it hurts too much. They are unable to work and their mental health has been affected.

“At this point, the flare-up is starting to sound like a pain syndrome. So, unless there are obvious red flags, there is little gained in doing an MRI,” she said.

Calm down the dysregulation

Assuming the patient has a chronic pain syndrome, and not an acute injury, McSwan says a few simple techniques can work.

“In place of opioids, patients with severe low back pain could be given low intensity heat wrap therapy for a prolonged period, prompted to walk regularly within their pain threshold and simple analgesia only if appropriate.

“Giving patients a plan is reassuring and will help them to self-monitor and only return to ED if they deteriorate or have red flag symptoms.”

Managing patient expectations

Even though this approach has been shown to work in ED settings, McSwan warns that denying people medication could cause distress.

“Most patients with severe pain expect medication, so it can be really hard to use a different approach,” she said.

Likewise, telling someone an MRI is unnecessary could be invalidating, she warned.

“It might come across as though you are not taking the pain seriously — or that you think it’s all in the patient’s head.

“No-one with a suspected slipped disk or torn ligament wants to hear that their agony is just pain syndrome or a limbic response.”

With this in mind, McSwan said good communication is essential, as is talking through the rationale for your diagnosis.

“After collecting their history, you might want to provide the evidence that explains the pain syndrome. At the same time, you should still acknowledge that their pain is very real and affecting them.

“Just because there isn’t a mechanical reason for it, it doesn’t make the pain any more tolerable. It just necessitates a different treatment approach,” she concluded.

Joyce McSwan

Top image credit: iStock.com/Cinefootage Visuals