Back Pain — Causes, Symptoms, Diagnosis & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Back pain is the single leading cause of disability worldwide, affecting 619 million people globally (7.5% of the world population) and representing the largest contributor to years lived with disability (YLDs) in the Global Burden of Disease Study — accounting for estimated $635 billion in annual direct and indirect costs in the United States alone. It most commonly affects the lumbar spine (lower back — L1-S1 vertebral region) but can also involve the thoracic or cervical spine. Non-specific low back pain — defined as lumbar pain with no identifiable serious underlying pathological cause (no nerve root compression, fracture, infection, or malignancy) — accounts for 80-90% of all back pain presentations and has an excellent natural history; most acute episodes resolve within 4-6 weeks regardless of treatment, though 30-40% develop persistent or recurrent symptoms at 1 year. Specific (secondary) back pain: disc herniation with radiculopathy (6-7%), lumbar spinal stenosis (3-4%), vertebral compression fracture (especially in osteoporotic older women), spondylolisthesis (anterior slippage of one vertebra on another), and rare but serious 'red flag' pathology (malignant spinal cord compression, vertebral osteomyelitis/discitis, cauda equina syndrome — each less than 1% but requiring urgent diagnosis and treatment). Inflammatory back pain from ankylosing spondylitis or axial spondyloarthritis accounts for approximately 5% of all chronic low back pain presentations and is systematically underdiagnosed due to a diagnostic delay averaging 7-10 years.

Back pain results from structural, inflammatory, or psychosocial causes — often in combination. Most common structural causes: lumbar disc herniation (nucleus pulposus extrusion through an annular tear, compressing nerve root — causing radiculopathy); degenerative disc disease (loss of disc height, annular fissures, end-plate damage — from ageing, genetics, and mechanical loading); facet joint osteoarthritis (zygapophyseal joint degeneration — causing local back pain and referred buttock pain); lumbar spinal stenosis (narrowing of the spinal canal from spondylosis, facet hypertrophy, and ligamentum flavum thickening — causing neurogenic claudication in older adults); vertebral compression fracture (from osteoporosis, malignancy, or trauma — most commonly T12-L1 vertebrae); and spondylolisthesis (anterior displacement of a vertebral body on the one below — most commonly L4-L5 or L5-S1, due to spondylolysis in young athletes or degenerative instability in older adults). Muscle strain and paraspinal ligament sprain are the most common acute causes (typically resolving in 2-6 weeks). Psychosocial and lifestyle risk factors — 'yellow flags' predicting chronicity: fear-avoidance behaviour (catastrophising, fear of movement/re-injury), poor self-efficacy, job dissatisfaction, depression, and anxiety are stronger predictors of chronic disability than structural MRI findings. Modifiable risk factors: sedentary behaviour, poor core muscle conditioning, obesity (increases lumbar compressive load), smoking (impairs disc nutrition via reduced end-plate diffusion, reduces healing), heavy repetitive lifting with poor ergonomics, and vibration exposure (truck drivers, heavy machinery).

Non-specific low back pain: typically presents as dull or aching lumbar pain, sometimes with diffuse radiation into the buttocks or posterior thighs (somatic referral — not following a dermatomal pattern); worsens with sustained static postures (prolonged sitting or standing), bending or lifting, and often eases with rest, movement, or change in position. Lumbar disc herniation with radiculopathy (sciatica): sharp, burning, or electric pain radiating from the buttock down the leg following a specific dermatomal distribution — L4 dermatome (medial leg, big toe; quadriceps weakness, reduced knee reflex); L5 dermatome (dorsum of foot, first web space; extensor hallucis longus weakness, foot drop); S1 dermatome (lateral foot, little toe; gastrocnemius weakness, absent ankle reflex); the straight leg raise test (SLR) is positive when leg pain reproduces below 60 degrees of hip flexion. Lumbar spinal stenosis: neurogenic claudication — bilateral leg pain, heaviness, numbness, or weakness with standing or walking, characteristically relieved by sitting or leaning forward (spinal flexion opens the canal); the 'shopping trolley sign' — patients lean on a trolley to achieve lumbar flexion. Vertebral fracture: sudden-onset severe back pain following minimal or no trauma in an older adult with risk factors for osteoporosis; extremely localised vertebral tenderness to percussion. Red flag symptoms requiring urgent investigation: bladder or bowel dysfunction (urinary retention, incontinence — cauda equina syndrome — emergency); bilateral leg weakness or progressive neurological deficit; saddle anaesthesia (perineal numbness); systemic symptoms (fever, unexplained weight loss, night sweats — infection or malignancy); back pain in a patient with known malignancy; age above 50 with new back pain; or severe constant pain not relieved by rest or positional change.

Most back pain is diagnosed clinically — a thorough history (onset, character, radiation pattern, aggravating and relieving factors, neurological symptoms, red flags, psychosocial yellow flags) and physical examination (inspection for scoliosis or kyphosis, paraspinal muscle spasm, range of motion testing, palpation for vertebral tenderness, SLR test, neurological examination of L4/L5/S1 myotomes and reflexes) provide sufficient information to guide management in the absence of red flags. Investigations should be reserved for clinical need: MRI of the lumbar spine is the gold standard for disc herniation with radiculopathy (demonstrating nerve root compression at the relevant level), spinal stenosis (central or lateral recess narrowing), cord and conus pathology, vertebral osteomyelitis, and malignant infiltration — the NICE 2016 guideline cautions against routine imaging in non-specific low back pain as it does not improve outcomes and may increase unnecessary intervention; cauda equina syndrome is an MRI emergency (same-day scan and neurosurgical review). CT myelography: useful when MRI is contraindicated or post-operative assessment. X-ray (plain lumbar radiographs): detects vertebral compression fractures, spondylolisthesis, gross scoliosis, and advanced spondylosis — not appropriate for disc or soft tissue pathology; still appropriate as initial investigation in suspected fracture or spondylolisthesis. DEXA scan: indicated in vertebral fracture to assess bone mineral density and guide osteoporosis treatment. Blood tests (FBC, CRP, ESR, protein electrophoresis, PSA, Ca2+, ALP): for suspected infection, malignancy, or inflammatory back pain — CRP and ESR are elevated in vertebral osteomyelitis, malignancy, and axial SpA.

Acute non-specific low back pain: the key principle is to stay active and avoid bed rest (bed rest worsens outcomes and delays recovery). Analgesia: paracetamol 1 g four times daily (weak evidence for isolated use in LBP); NSAIDs (naproxen 500 mg BD, ibuprofen 400-800 mg TDS, diclofenac 75 mg BD) — most effective analgesics for acute LBP; add PPI gastroprotection with regular NSAID use; short courses of diazepam 2-5 mg for acute muscle spasm. Heat therapy (heat packs or hot water bottle) provides short-term pain relief. Manual therapy: physiotherapy, spinal manipulation (osteopathy, chiropractic), and massage — provide equivalent short-term relief to NSAIDs for acute LBP. Reassurance and education — advising that most acute LBP will resolve within 6 weeks regardless of treatment is a powerful therapeutic intervention. Chronic low back pain: structured exercise programme (the most evidence-based intervention overall) — core strengthening (targeting transversus abdominis, multifidus), aerobic exercise, yoga, Tai Chi, and Pilates all have equivalent efficacy; physiotherapy-led programmes are more effective than home exercises alone. Pain neuroscience education and cognitive behavioural therapy (CBT) — reduces pain catastrophising, fear-avoidance, and disability more effectively than drugs for chronic LBP; recommended in NICE LBP guidelines as primary treatment. Pharmacological: duloxetine 60-120 mg/day (licensed for chronic LBP; moderate evidence); low-dose amitriptyline (10-25 mg nocte) for neuropathic or sleep-disrupted LBP; weak opioids (tramadol 50-100 mg QDS) — short-term, monitor carefully; strong opioids not recommended for long-term LBP (risk outweighs benefit). Epidural corticosteroid injections: effective short-term (4-12 weeks) pain relief in lumbar radiculopathy from disc herniation or stenosis; typically up to 3 injections per year per level; guided by fluoroscopy or CT. Lumbar medial branch blocks and facet joint injections for confirmed facet arthropathy. Surgery: microdiscectomy (removal of herniated disc fragment causing persistent radiculopathy after 6-12 weeks) — equivalent long-term outcomes to conservative care but provides faster symptom relief; lumbar decompression (laminectomy or foraminotomy) for confirmed spinal stenosis with neurogenic claudication; spinal fusion — reserved for instability, spondylolisthesis, or deformity; lower evidence base for fusion in degenerative disc disease. Cauda equina syndrome: emergency neurosurgical decompression within hours of symptom onset — every hour of delay worsens prognosis for bladder and bowel recovery.

Untreated cauda equina syndrome — compression of the cauda equina nerve roots from a massive disc herniation — causes permanent paralysis, bladder and bowel incontinence, and sexual dysfunction if not decompressed within hours. Chronic back pain leads to depression, anxiety, sleep disturbance, opioid dependence, and significant disability. Progressive disc disease and spinal stenosis can worsen neurological function over time. Untreated vertebral osteomyelitis (spinal infection) can cause spinal instability, abscess formation, and sepsis. Early diagnosis and appropriate treatment prevent serious long-term complications.

Regular core strengthening and back extension exercises are the most effective prevention strategy — yoga, Pilates, and swimming are particularly beneficial. Maintain healthy weight: obesity increases lumbar load significantly. Correct lifting technique: bend at the knees, keep the load close to the body, avoid twisting while loaded. Ergonomic workplace setup: adjustable chair with lumbar support, monitor at eye level, regular standing breaks. Quit smoking — nicotine impairs disc nutrition and healing. Stay active — sedentary behaviour is a major risk factor for chronic back pain.

Seek emergency care immediately (call 999 or go to A&E) for back pain with: bilateral leg weakness, numbness in both legs, or saddle anaesthesia (numbness around the genitals and inner thighs) — possible cauda equina syndrome requiring emergency neurosurgery; and new loss of bladder or bowel control. Seek urgent GP review (within 24-48 hours) for back pain red flags: fever with back pain (possible spinal infection or vertebral osteomyelitis); history of cancer with new back pain (possible spinal metastasis); severe constant back pain at rest and at night (not relieved by position change); unexplained weight loss with back pain; back pain following significant trauma (fall from height, road traffic accident — possible spinal fracture); immunocompromise or IV drug use (increased infection risk). Most acute low back pain (without red flags) is mechanical and does not require urgent investigation — reassure, maintain activity, use NSAIDs or paracetamol, and see a GP if not improving within 4-6 weeks.