History and exam

Key diagnostic factors

common

bladder dysfunction

Bladder dysfunction is always apparent at some stage in the progression of CES.[4][13] Urinary incontinence is due to overflow from retention. Earlier, more subtle signs of dysfunction 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.[7]

lower limb weakness

Varying degrees of lower limb muscle weakness are observed in patients with CES, but some patients never develop it.[4][7]

uncommon

saddle paraesthesia/anaesthesia

Saddle anaesthesia is typical of CES, and is a 'red flag'. More subtle alteration of saddle sensation (e.g., numbness, 'pins and needles') should be sought, especially in patients with low back pain and bilateral sciatica. In one study, objective saddle numbness was recorded in 59% of patients with CES, and normal saddle sensation in 29%.[7]

bowel dysfunction

Symptoms and signs include loss of sensation of rectal fullness, faecal incontinence, and laxity of the anal sphincter.[6] Across three studies, reduced anal tone was recorded in 22% of people with CES, and normal anal tone in 33%.[7]

Other diagnostic factors

common

low back pain

Back pain may be chronic (gradually worsening over time) or acute.[7] Usually present and can be severe if onset is acute, but may be resolving or even absent in some patients.[4]

sciatica

Bilateral sciatica is present in around 50% of patients with CES. However, sciatica may be unilateral, or absent altogether.[7]

uncommon

sexual dysfunction

Symptoms and signs include decreased sex drive, reduced sensation, erectile dysfunction, and reduced ability to achieve orgasm.[4] Estimates of the prevalence of sexual dysfunction vary; this is partly because it is often poorly documented.[36][20]

Risk factors

strong

lumbar disc herniation

The most common cause of CES overall. CES has been reported to be associated with 1% to 6% of all cases of lumbar disc herniation requiring surgery.[4]

spinal trauma

Vertebral fracture, disc rupture, or extra-axial haematoma due to trauma may result in CES.[2] This is usually an early development, but degenerative changes can slow symptom onset.

spinal surgery

Injury to the cauda equina can occur either during spinal surgery (from direct damage to the nerves) or postoperatively (due to haematoma). CES usually develops within 24 hours of surgery, but may not become apparent until later.[4]

spinal epidural abscess

Characterised by inflammation with accumulation of pus within the epidural space, which may compress the thecal sac and press on the cauda equina. Risk factors for spinal epidural abscess include diabetes mellitus, intravenous drug use, spinal trauma or surgery, indwelling spinal catheter, local or systemic infection, and immunosuppression (e.g., due to long-term systemic corticosteroid therapy).[11]

anticoagulation therapy

Anticoagulation therapy increases the risk of haematoma, particularly after neuraxial anaesthesia or spinal surgery.[4]

weak

spinal stenosis

The most common cause of thecal sac compression in older people. The progress of spinal stenosis is slow, and symptomatic CES affects only a relatively small number of patients with this condition.[2]

spinal tumour

A primary or (more commonly) metastatic spinal cord tumour below the first lumbar vertebra may compress the thecal sac and press on the cauda equina.[2] Typically, symptoms are of insidious onset, although this is not always the case (e.g., sudden vertebral body collapse due to weakening of bone by the tumour). 

aged under 50 years

Low back pain and other symptoms in a patient under 50 years is more likely to be indicative of acute CES than in older patients.[12]

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