What is Cauda Equina Syndrome?
A rare but serious complication in which a large central lumbar disc herniation (or other compressive lesion) presses on the bundle of nerves at the bottom of the spinal canal (the cauda equina). A medical emergency that requires urgent assessment and usually surgery.
Causes
Most commonly a large central lumbar disc herniation. Less commonly severe canal stenosis, epidural haematoma or abscess, tumour, or trauma.
Symptoms
Warning signs include: numbness around the saddle or groin area, loss of bladder or bowel control (or new difficulty passing urine), severe leg weakness (often bilateral), and sexual dysfunction. If you develop sudden severe leg weakness, loss of bowel or bladder control, or saddle numbness, attend the nearest emergency department straight away — these symptoms need urgent assessment.
Diagnosis
Urgent clinical assessment of perianal sensation, anal tone, lower-limb power and reflexes, and bladder function (including post-void residual). Any suspicion warrants immediate imaging.
Imaging
Urgent MRI of the lumbar spine to confirm compression and identify the cause. CT or CT myelography is used if MRI is unavailable.
Treatment
Urgent surgical decompression — usually within hours rather than days of presentation. Catheterisation and supportive care; bladder, bowel and sexual rehabilitation are often required afterwards.