Cauda Equina Syndrome: Red Flags Every Physio Must Recognise

Why CES is a physio responsibility

Most patients with early CES present with low back pain and leg symptoms - exactly the picture we see every day. The symptoms that distinguish CES from a simple radiculopathy are often missed because they feel awkward to ask about. Normalising the questions, and asking them at every lumbar assessment, is what catches the small number of true positives.

The core CES red flags

Any of the following should trigger immediate escalation for same-day MRI:

• New urinary retention or loss of bladder sensation (not being able to tell when the bladder is full or emptying).
• Urinary or faecal incontinence of new onset.
• Saddle or perineal anaesthesia or paraesthesia.
• Loss of anal tone or sensation.
• New sexual dysfunction (loss of genital sensation, erectile dysfunction of neurological onset).
• Bilateral leg pain, weakness, or sensory change - particularly if progressive.

Subjective questions to ask every lumbar patient

Frame the questions matter-of-factly. Patients are more likely to disclose if you make it routine rather than alarming.

• Any change in your ability to feel when you need to pass urine?
• Any difficulty starting, stopping, or controlling urination?
• Any new numbness or pins-and-needles between your legs, around your back passage, or in the genital area?
• Any new loss of bowel control or change in bowel sensation?
• Any new sexual symptoms - loss of sensation or function?
• Are your leg symptoms on both sides, and are they getting worse?

Objective screen

If any subjective red flag is positive, add: light-touch and pinprick across the S2–S5 dermatomes (saddle area), lower-limb neurological screen (myotomes, reflexes, sensation), and gait. Anal tone assessment is the physician's role, not the physiotherapist's - its absence on your screen does not rule CES out.

When and how to refer

Suspected CES requires same-day emergency department referral for urgent MRI. Do not wait for clinic letters or imaging requests. Call the ED, hand over the specific red flags you identified, and give the patient written information so they can advocate for themselves on arrival. Document everything: the exact questions you asked, the answers, the time, and the referral pathway you used.

Err on the side of referral. A false-positive referral costs the system a scan; a missed CES costs the patient their independence.

Key takeaways

• CES is rare but time-critical - delay to decompression predicts permanent disability.
• Ask bladder, bowel, saddle, and sexual function questions at every lumbar assessment.
• Any positive red flag warrants same-day ED referral for emergency MRI.
• Document the exact questions, answers, and referral pathway.
• When in doubt, refer - the cost of a false positive is far smaller than a missed CES.

Frequently asked questions

What is cauda equina syndrome?

Cauda equina syndrome is compression of the lumbosacral nerve roots below the conus medullaris, most commonly from a large central disc herniation. It causes bladder, bowel, saddle, and sexual dysfunction and is a surgical emergency requiring urgent decompression.

What should a physiotherapist do if they suspect cauda equina?

Refer the patient to the emergency department the same day for urgent MRI. Do not wait for outpatient pathways. Call ahead, document the red flags identified, and give the patient written information to take with them.

Is back pain alone a red flag for cauda equina?

No. Back pain in isolation is extremely common and not a CES red flag. The red flags are new bladder, bowel, saddle, or sexual dysfunction, and bilateral progressive leg symptoms - usually on a background of back or leg pain.