AKT · Musculoskeletal/Spine & back

Lower back pain & sciatica

Mechanical/non-specific back pain; sciatica = lumbosacral nerve-root compression

Overview

Low back pain is usually non-specific and self-limiting; sciatica is radicular leg pain from lumbosacral nerve-root compression (often a disc prolapse). The key skill is triage: recognise the red flags for a serious cause (cauda equina, malignancy, infection, fracture) while managing the large majority conservatively with the STarT Back risk-stratified approach.

Recognise

Non-specific: activity-related lumbar pain without radicular or systemic features; recovers in weeks
Sciatica: unilateral leg pain (below the knee) ± paraesthesia/weakness in a dermatomal/myotomal pattern; positive straight-leg raise
Red flags prompt urgent assessment (see below)

Red flags

Cauda equina syndrome: bilateral sciatica, saddle anaesthesia, urinary retention/incontinence, faecal incontinence, reduced anal tone → EMERGENCY MRI
Malignancy (age >50, history of cancer, weight loss, night pain, thoracic pain), infection (fever, IVDU), fracture (trauma, osteoporosis, steroids)

Differentials & how to tell them apart

Cauda equina syndromethe can't-miss — bilateral/saddle symptoms, bladder/bowel dysfunction → emergency

Spinal stenosisneurogenic claudication: pain on walking/standing relieved by sitting/flexion (older patient)

Vertebral fracture / malignancy / infectionred-flag features; abnormal imaging

Inflammatory back pain (AS)young, worse with rest/better with exercise, prolonged morning stiffness

Investigations

Clinical assessment + red-flag screen; STarT Back tool for prognostic stratification; NO routine imaging for non-specific low back pain. URGENT MRI if cauda equina/serious pathology suspected; MRI before considering surgery for persistent radiculopathy.

Management

Stay active + NSAID + STarT Back-guided physiotherapy; urgent MRI if red flags

1Screen for red flags first. For non-specific back pain/sciatica: encourage activity, reassure, and use the STarT Back tool to guide physiotherapy; NSAIDs at the lowest effective dose. No routine imaging.Gate: Cauda equina features (bilateral sciatica, saddle anaesthesia, bladder/bowel dysfunction, reduced anal tone) → EMERGENCY MRI and surgical decompression — this is the single most important not-to-miss.
2Persistent radicular pain → MRI and consider an epidural injection or surgical decompression/discectomy; investigate and treat any serious underlying cause (malignancy/infection/fracture).

Self-management: stay active, reassurance, education; STarT Back-guided physiotherapy — first-line — bed rest is harmful; most recover

NSAID at the lowest effective dose (+PPI) — first-line analgesia; do NOT offer paracetamol alone, and avoid routine opioids

Sciatica: neuropathic agents are NOT routinely recommended — NICE advises against gabapentinoids for sciatica; consider an epidural local-anaesthetic/steroid injection for acute severe radicular pain

Surgery (discectomy/decompression) — for radiculopathy not improving with conservative care, or for serious pathology

Key points

Most low back pain is non-specific → stay active + NSAID + STarT Back physio, no imaging. Sciatica = radicular leg pain (positive SLR). The emergency is cauda equina (bilateral sciatica + saddle anaesthesia + bladder/bowel dysfunction) → immediate MRI. NICE advises against gabapentinoids for sciatica.

Monitor & prognosis

Recovery/function, red-flag re-screening, response to physio.

Most non-specific back pain and sciatica resolve; cauda equina outcome depends on speed of decompression.

Source: NICE NG59 (low back pain & sciatica)