Lesson Plan – Back Pain (Induction)

It’s really important to ask about the red flag symptoms that might point towards a serious diagnosis such as cauda equina syndrome. In a patient of this age cancer (primary or metastatic) is less likely, but some simple screening questions such as unexplained weight loss, history of cancer and night pain are quick to ask and easy for the patient to answer.

If there is concern about cauda equina syndrome (and we must always rule out the serious diagnoses in the ED) ask about a history of difficulty emptying the bladder or bowels, pain and/or weakness in both legs and saddle-area anaesthesia over dermatomes S2, S3, S4 and S5 (a late sign).

There aren’t really any features of the clinical examination that can rule out cauda equina. The only feature that had a useful likelihood ratio in one series^​2,3​ was urinary retention (LR+16.5). It always performed, but the PR examination isn’t really that discriminative at all.

Once cauda equina enters the differential diagnosis there is really only one investigation to rule out (or rule in) the diagnosis: MRI. Discuss with your facilitator how this would take place in your Trust.

Firstly, don’t be distracted by this patient’s urge to leave or that he is in the Minors area. Stick to ruling out the “worst case scenario”. At this chap’s age his back pain really could be anything, including a ruptured AAA. Ask a detailed history about when the pain came on. Does he have a history of ischaemic heart disease or vascular disease?

Ask for (or measure yourself) a set of vital signs. Be even more suspicious if the patient is tachycardic or hypotensive (remember a fall in blood pressure may be relative and what’s “normal” for a 25 year old could be very low for a 76 year old). Gently feel his abdomen – is there a pulsatile mass?

If AAA still hasn’t been ruled out, urgently talk to your senior Emergency Physician on shift. This patient needs a point of care ultrasound, which should be possible in most Emergency Departments

If you haven’t already move the patient to the resuscitation room and ask your senior to join you at the bedside. You will manage this patient’s care together from now on.

Ensure the patient has adequate intravenous access and that a sample has been sent to the blood bank to type and cross match his blood. Give him pain relief, but be cautious so ask not to drop his blood pressure or make him feel sick (vomiting will increase his intraabdominal pressure and also make an anaesthetic more hazardous).

If this patient’s ultrasound confirms a AAA and the patient has other signs, especially hypotension, the surgical team may want to take him straight to theatre. If the ED team, anaesthetics and surgery think he is going to remain haemodynamically normal he may go for a CT scan prior to theatre for operative planning.

The immediate thought is that this patient has musculoskeletal back and he probably has. BUT, we need to actively consider the serious diagnoses in all patients. A quick run through the “red flags” will help…

• neurological symptoms (especially altered sensation, disturbance of bladder and bowel function)
• weight loss
• known cancer (especially those which commonly metastatise to bone)
• fever or night sweats (consider infection especially TB)
• coagulopathy including patients on warfarin or DOACs
• immonosuppression

Double check that the patient’s neurology is normal in their legs.

Do a range of motion test of the patient to assess how restricting their pain is.

Not every patient with back pain needs a PR examination – only do this if you truly think there is a chance the patient may have neurological involvement.

If you think this pain is muscular and there are no red flags the answer is none

This patient needs analgesia and sensible advice about how to manage their pain.

They should start with paracetamol and a NSAID (if no contraindications) and if severe you may want to add in a opiod such as dihydrocodeine.

Benzodiazepines such as diazepam are often given as ‘muscle relaxants’ (sic) but if you remember the pharmocology they are really ‘patient relaxants (via GABA receptors). If the patient is acutely distressed by the pain these drugs may help to settle the situation down, but must only be used short term.

There are many excellent advice sheets available for patients. This one from Oxford is a good example.