Define Cauda Equina Syndrome. Describe its causes, clinical features and management.
Definition
Cauda equina syndrome (CES) is compression of the lumbosacral nerve roots below the conus medullaris (below ~L1), producing a characteristic pattern of bladder/bowel dysfunction, saddle anaesthesia and lower-limb weakness. It is a surgical emergency because delayed decompression risks permanent sphincter and sexual dysfunction.
Causes
The commonest cause is a large central lumbar disc prolapse (typically L4–L5 or L5–S1); other causes include tumour, epidural abscess or haematoma, spinal stenosis, and trauma.
Clinical Features (red Flags)
The warning features are urinary retention with overflow incontinence (or altered bladder sensation), faecal incontinence / loss of anal tone, saddle (perineal) anaesthesia, bilateral sciatica or leg weakness, and sexual dysfunction. Per-rectal examination assesses tone and perianal sensation. Painless urinary retention with a large post-void residual is a particularly ominous sign.
DANGER / REMEMBER
Bilateral sciatica with any bladder/bowel disturbance or saddle numbness is CES until proven otherwise. Do not wait for ‘complete’ signs — arrange an urgent MRI and emergency decompression; outcome depends on early surgery, ideally before retention becomes established.
Management
Urgent MRI of the whole lumbosacral spine confirms the level and cause. Treatment is emergency surgical decompression (e.g. Discectomy/laminectomy, or drainage of an abscess/haematoma). The bladder is catheterised; steroids are given if the cause is tumour. Earlier decompression gives better recovery of sphincter function.
Incomplete VS Complete & Prognosis
CES is described as incomplete (CES-I) — altered urinary sensation and difficulty voiding but without painless retention — or complete (CES-R), with painless retention and overflow incontinence. Outcome is markedly better when decompression is performed in the incomplete stage, before painless retention becomes established; this is why urgent recognition and imaging are stressed. Recovery of bladder, bowel and sexual function is the principal determinant of long-term disability.
A surgical emergency — delay causes permanent incontinence.
| Red flag | Finding |
|---|---|
| Saddle anaesthesia | Perineal sensory loss |
| Bladder dysfunction | Retention with overflow incontinence |
| Bowel dysfunction | Loss of anal tone, incontinence |
| Motor | Bilateral progressive leg weakness |
| Action | Urgent MRI + decompression within 48 hours |
KEY POINT
Key points TO remember
- CES = compression of lumbosacral roots below the conus; a surgical emergency.
- Commonest cause: large central lumbar disc prolapse.
- Red flags: retention/incontinence, saddle anaesthesia, bilateral sciatica, ↓ anal tone.
- Urgent MRI + emergency decompression; earlier surgery = better sphincter recovery.
EXAM TIP
Sources: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.
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