Lumbar Disc Herniation
Displacement of nucleus pulposus material beyond the disc space, commonly causing radiculopathy through compression of a nerve root.
Overview
Lumbar disc herniation occurs when nucleus pulposus extrudes through a defect in the annulus fibrosus, most often posterolaterally into the lateral recess where it compresses the traversing nerve root. L4/5 and L5/S1 account for the majority of symptomatic herniations. Natural history is favourable, with most symptomatic herniations resorbing partially and producing symptom relief over weeks to months.
Epidemiology
Lifetime prevalence of sciatica is around 13 to 40 percent; symptomatic disc herniation accounts for a minority of these. Peak presentation is in the fourth and fifth decades. Heavy lifting, prolonged driving, smoking, and genetic factors are recognised risk factors.
Symptoms
Dermatomal leg pain typically exceeding the back pain component, often with positive straight leg raise (Lasègue) or crossed straight leg raise. Neurological examination may reveal a focal motor or sensory deficit corresponding to the affected root. Cauda equina syndrome, with saddle anaesthesia, bladder dysfunction, and bilateral leg symptoms, is a surgical emergency.