History and exam
Key diagnostic factors
common
bladder dysfunction
Bladder dysfunction is a red-flag symptom for CES in any patient who presents with leg pain and/or back pain. If symptoms are of recent onset (<14 days) or deteriorating, this warrants immediate referral for emergency MRI scanning.[14][15][16][17][18]
A cohort study of 621 UK patients with CES found that 83% had bladder dysfunction symptoms at presentation.[22]
Early signs of dysfunction may be subtle and include: reduced awareness of full bladder; loss of urge to urinate; urgency; difficulty in starting or stopping the urine stream; reduced awareness that urination is occurring; recent-onset or progressively worsening weak urine stream.[8]
Urinary incontinence is due to overflow from retention and is an indicator of late-stage, potentially irreversible CES. Palpation may reveal a full bladder due to urinary retention.
Practical tip
When patients have acute back and/or leg pain, they often emphasise this and overlook subtle symptoms of CES such as early bladder symptoms (e.g., mild changes in urinary sensation, flow, and/or frequency).[4][25]
It is therefore vital to ask very specific, direct questions. Explain why you are asking these questions as patients are usually not aware of the possible link between back pain and urinary symptoms.
Practical tip
Urinary dysfunction is very common in older people, making it challenging to distinguish possible CES from other age-related symptoms. Impaired sensation is a strong pointer to consider the possibility of CES. Good discriminatory questions to ask the patient are:
Do you know when you need to pass urine?
Can you stop and start the flow of urine without trouble?
Does it feel normal when you pass urine?
saddle paraesthesia/anaesthesia
A change in perianal, perineal, or genital sensation is a red-flag symptom for CES in any patient who presents with leg and/or back pain. If symptoms are of recent onset (<14 days) or deteriorating, this warrants immediate referral for emergency MRI scanning.[14][15][16][17][18]
A cohort study of 621 UK patients with CES found that 81% reported saddle numbness at presentation.[22]
Altered sensation of these 'saddle' areas (S2-S5 dermatomes) may be subjectively reported by the patient or objectively tested on examination. The affected area may be small or as large as a horse's saddle.[14][15]
Practical tip
When patients have acute back and/or leg pain, they often emphasise this and overlook subtle symptoms of CES such as perineal numbness.[4][25]
It is vital to ask specific, direct questions about the presence or absence of each red-flag symptom. For example, if a patient presents with low back pain and sciatica, ask if they have any 'pins and needles' around their back passage, buttocks, or genitals.
lower limb weakness
A severe or progressive neurological deficit affecting both legs (e.g., major motor weakness of foot dorsiflexion, ankle eversion, or knee extension) is a red-flag symptom for CES in any patient who presents with back and/or leg pain. If symptoms are of recent onset (<14 days) or deteriorating, this warrants immediate referral for emergency MRI scanning.[14][15][16][17][18]
diminished or absent lower limb reflexes
Assess for any reflex changes (ankle, knee, plantar). There may be diminished reflexes, depending on the nerve root affected.
uncommon
bowel dysfunction
Bowel dysfunction is a red-flag symptom for CES in any patient who presents with leg and/or back pain. If symptoms are of recent onset (<14 days) or deteriorating, this warrants immediate referral for emergency MRI scanning.[14][15][16][17][18]
A cohort study of 621 UK patients with CES found that 39% had bowel dysfunction at presentation.[22]
Symptoms and signs include loss of sensation of rectal fullness, changed sensation when passing a bowel movement, and laxity of the anal sphincter. Faecal incontinence is an indicator of late-stage CES.
A digital rectal examination (DRE) is not necessary for a community-based presentation of suspected CES.[15] It is important, however, to document the patient's subjective assessment of perianal sensation. In the hospital setting, a DRE can be considered for assessment of anal tone and presence of voluntary anal contraction but is not essential.
The value of DRE in the acute diagnosis of CES has been questioned, and it is not required to meet the index of suspicion that justifies an emergency request for MRI.[14]
Other diagnostic factors
common
sciatica (radicular pain)
Sciatica (i.e., pain that radiates from the lower back to the buttock and leg) is a typical but non-specific presenting symptom of CES.[14][15][16]
A cohort study of 621 UK patients with CES found that sciatica was recorded in 93% of patients at presentation.[22]
If a patient presents with sciatica together with recent onset (<14 days) of, or deterioration of, any one or more of the following CES red-flag symptoms, an immediate referral for emergency MRI is warranted:[14][15][16][17][18]
Disturbance of bladder function
Disturbance of bowel function
Altered sensation around the perianal, perineal, or genital ('saddle') areas, either subjectively reported or objectively observed
Severe or progressive neurological deficits affecting both legs
Sexual dysfunction
If a patient has bilateral sciatica but without any red-flag symptoms or signs for CES, UK guidelines recommend an urgent referral to the musculoskeletal medicine service (to be seen within 2 weeks).[14][15][16]
low back pain
Back pain is a typical but non-specific presenting symptom of CES.[14][15][16]
A cohort study of 621 UK patients with CES found that 97% had back pain at presentation, making it the most frequently reported symptom.[22]
If a patient presents with back pain together with recent onset (<14 days) of, or deterioration of, any one or more of the following CES red-flag symptoms, an immediate referral for emergency MRI is warranted:[14][15][16][17][18]
Disturbance of bladder function
Disturbance of bowel function
Altered sensation around the perianal, perineal, or genital ('saddle') areas, either subjectively reported or objectively observed
Severe or progressive neurological deficits affecting both legs
uncommon
sexual dysfunction
Sexual dysfunction is a red-flag symptom for CES in any patient who presents with sciatica. If symptoms are of recent onset (<14 days) or deteriorating, this warrants immediate referral for emergency MRI scanning.[14][15][16][17][18]
Estimates of the prevalence of sexual dysfunction vary; this is partly because it is often poorly documented.[31][32] A cohort study of 621 UK patients with CES found that sexual dysfunction was recorded as a presenting symptom for 38%.[22]
Symptoms and signs include reduced sensation, erectile dysfunction, and reduced ability to achieve orgasm.[6]
Practical tip
Low back pain with sexual dysfunction as the only other feature is unlikely to be due to CES.[15]
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