AKT · Musculoskeletal/Spine & backlow yield

Intervertebral disc prolapse

Herniation of nucleus pulposus through the annulus → nerve-root compression

Overview

Herniation of the disc's nucleus pulposus through the annulus fibrosus, compressing an adjacent nerve root and causing radicular pain (sciatica in the lumbar spine, brachialgia in the cervical spine). Most resolve with conservative management; the surgical concern is a large central prolapse causing cauda equina syndrome.

Recognise

Dermatomal radicular pain ± paraesthesia and myotomal weakness; lumbar (L5/S1 commonest) → sciatica, cervical → arm pain
Positive straight-leg raise (lumbar); specific root signs (e.g. L5 → weak big-toe dorsiflexion/foot drop; S1 → reduced ankle reflex)
Pain often worse on coughing/straining/sitting

Red flags

Central prolapse → cauda equina syndrome (bilateral symptoms, saddle anaesthesia, bladder/bowel dysfunction) → emergency MRI
Progressive motor weakness (e.g. foot drop) → earlier surgical referral

Differentials & how to tell them apart

Cauda equina syndromecentral prolapse with bilateral/saddle/bladder features — emergency

Spinal stenosisneurogenic claudication, older patient, flexion relieves

Peripheral nerve entrapment / hip pathologynon-dermatomal, local signs

Investigations

Clinical (dermatomal pattern, SLR, root signs); MRI is the imaging of choice but only if symptoms persist, there is progressive weakness, or surgery/serious pathology is being considered — not routinely early.

Management

Conservative (stay active + NSAID + physiotherapy); discectomy for persistent/progressive disease

1Diagnose from the dermatomal radicular pattern and root signs. Manage conservatively — stay active, NSAID analgesia and physiotherapy — as most resolve.Gate: A central prolapse causing cauda equina syndrome, or progressive motor weakness (foot drop), → urgent MRI and surgical referral, not conservative management.
2Persistent severe radicular pain → epidural injection; persistent radiculopathy or progressive deficit → discectomy/microdiscectomy after MRI.

Conservative: stay active, analgesia (NSAID), physiotherapy — first-line — most prolapses resolve over weeks; bed rest is harmful

Epidural local-anaesthetic/steroid injection — for acute severe radicular pain not settling

Surgical discectomy / microdiscectomy — for persistent/severe radiculopathy or progressive neurological deficit

Avoid routine gabapentinoids for sciatica — NICE advises against them for sciatica

Key points

Dermatomal radicular pain + positive SLR + a root sign (L5 foot drop, S1 reduced ankle jerk) = disc prolapse → mostly conservative (stay active, NSAID, physio). The surgical emergency is a central prolapse causing cauda equina; progressive weakness warrants earlier surgery.

Monitor & prognosis

Symptom resolution, neurological signs, response to conservative care.

Most resolve conservatively over weeks to months; surgery helps persistent radiculopathy.

Source: NICE NG59; cross-ref neurology