Discogenic compression of the cauda equina: a surgical emergency

The syndrome of cauda equina compression due to central disc rupture is uncommon but its importance greatly transcends its rarity. Key symptoms and signs are bilateral leg pain, weakness or numbness (although unilateral symptoms or even absence of leg pain do not exclude the diagnosis), perineal numbness and, in 60% of patients, bladder and bowel incompetence ranging from dysuria to vesical and anal sphincter paralysis. Diagnosis and treatment are often delayed due to lack of recognition of the condition and failure to appreciate the surgical imperative for its treatment. At the present time myelography is the one essential investigation, although this may become supplanted in time by magnetic resonance imaging. Arrangements for myelography should be planned so that immediate operation can be commenced following the procedure. The onset of disc rupture may be acute and massive and result in intradural sequestration of disc fragments in 7.5% of cases. Intradural exploration and/or transdural sequestrectomy avoids traction on already compromised nerve roots and is often safer than extradural sequestrectomy. The onset of bladder paralysis is a most important indication for immediate surgery. The cases presented show that there is a highly significant difference in the outcome of those cases operated on within 24h of bladder paralysis compared to those operated on after this period.