Sciatica — Causes, Diagnosis, Treatment & Exercises Guide — Symptoms, Causes & Treatment | MyMedicPlus

Sciatica (lumbar radiculopathy) is a symptom complex caused by compression, inflammation, or irritation of one or more of the lumbar or sacral nerve roots that form the sciatic nerve — the longest and thickest nerve in the human body, arising from nerve roots L4, L5, S1, S2, and S3, and running from the lower back through the buttock, posterior thigh, and down to the foot. True sciatica presents as radiating pain that travels from the lower back into the buttock, posterior or lateral thigh, calf, and foot — following the dermatomal distribution of the affected nerve root. It is associated with neurological symptoms including numbness, tingling (paraesthesia), and muscular weakness in the same distribution. Sciatica is common — with a lifetime incidence of 10-40% and annual prevalence of 2-3% in the adult population; peak age of onset is 40-60 years, correlating with the age of peak disc degeneration. The most common cause is lumbar disc herniation (prolapsed intervertebral disc) at L4-L5 or L5-S1 — accounting for 90% of sciatica cases. The prognosis is generally good — approximately 90% of patients with acute sciatica from disc herniation improve spontaneously within 6-12 weeks with conservative management. However, severe neurological deficit, rapid progression, or failure to improve warrants imaging and specialist referral. Cauda equina syndrome — bilateral leg weakness, saddle anaesthesia, and loss of bladder or bowel control from central disc prolapse — is a surgical emergency requiring same-day MRI.

Lumbar disc herniation (PIVD — prolapsed intervertebral disc): the most common cause, accounting for 90% of sciatica. The nucleus pulposus (the gelatinous inner core of the intervertebral disc) herniates through a tear in the annulus fibrosus and compresses the adjacent nerve root in the lateral recess or foramen — typically at L4-L5 (L5 nerve root — lateral foot and big toe symptoms) or L5-S1 (S1 nerve root — heel and lateral foot symptoms). Disc herniation is both mechanical (nerve compression) and chemical (nucleus pulposus material is inflammatory — produces phospholipase A2, TNF-alpha, IL-6 — explaining why inflammation-reducing treatments are effective even with persistent compression). Lumbar spinal stenosis: degenerative narrowing of the spinal canal from osteophytes, ligamentum flavum hypertrophy, and disc bulging — causes neurogenic claudication (bilateral leg pain and weakness on walking that is relieved by sitting or leaning forward — distinguishes from vascular claudication). Piriformis syndrome: entrapment of the sciatic nerve by the piriformis muscle in the deep buttock (through or below the muscle) — a diagnosis of exclusion when imaging of the spine is normal. Spondylolisthesis: forward slipping of one vertebra on the one below — L4/L5 or L5/S1 — causing foraminal stenosis and nerve root compression. Less common causes: epidural haematoma or abscess (emergency), sacroiliac joint dysfunction, pelvic tumours compressing the sciatic nerve, pregnancy (uterine pressure on the sciatic nerve — most common in the third trimester). Risk factors: occupational heavy lifting, bending, and whole-body vibration (lorry drivers, farmers); sedentary lifestyle; obesity; tall stature; smoking (reduces disc vascularity and accelerates degeneration); age 40-60 (peak disc degeneration); and prior episodes of sciatica.

The cardinal symptom of sciatica is radiating leg pain following a dermatomal distribution, typically described as sharp, shooting, electric, burning, or lancinating pain that travels from the lower back or buttock down the posterior or lateral thigh and calf to the foot. Pain typically unilateral (bilateral in central disc prolapse or spinal stenosis). Dermatomal patterns by nerve root: L4 nerve root (disc herniation at L3-L4) — medial lower leg and medial foot (medial malleolus); weakness of knee extension (quadriceps); reduced knee jerk reflex. L5 nerve root (L4-L5 disc — most common) — lateral lower leg, dorsum of foot, and big toe; weakness of foot dorsiflexion (foot drop) and big toe extension (extensor hallucis longus); no reflex change (L5 has no reliable reflex). S1 nerve root (L5-S1 disc — second most common) — posterior calf and heel, lateral foot and small toe; weakness of foot plantarflexion and toe standing; reduced or absent ankle jerk reflex. Neurological symptoms: numbness (anaesthesia) and tingling (paraesthesia) in the dermatomal territory; muscle weakness (motor deficit) in the myotomal territory — weakness worsens with fatigue. Examination findings: positive straight leg raise (SLR) test — raising the straight leg to 30-70 degrees reproduces leg pain below the knee (sensitivity 80%, specificity 40% for disc herniation); positive Lasegue's sign; positive crossed SLR (pain in the affected leg when contralateral leg raised — highly specific for disc herniation); lumbar paravertebral muscle spasm; scoliotic tilt away from the painful side; and limited lumbar flexion. Red flags for cauda equina syndrome: bilateral leg pain or weakness; saddle area (perineum, genitalia, inner thighs) numbness or paraesthesia; loss of bladder control (urinary retention or incontinence); loss of bowel control — requires same-day emergency MRI and neurosurgery referral.

Sciatica is primarily a clinical diagnosis based on history (typical radiating leg pain in a dermatomal pattern with neurological symptoms) and physical examination (positive SLR, neurological deficit). Imaging is not routinely required for acute sciatica — 90% resolve within 6-12 weeks regardless of the specific cause, and imaging findings (disc bulges, degeneration) are extremely common in asymptomatic individuals. MRI lumbar spine (without contrast): the gold standard imaging modality for sciatica — directly visualises disc herniation, nerve root compression, foramen narrowing, spinal stenosis, spondylolisthesis, and canal dimensions; T2-weighted sagittal and axial sequences are most diagnostic. Indicated for: failure to improve with 6 weeks of conservative treatment; progressive neurological deficit; suspected cauda equina syndrome (emergency); severe or worsening weakness; suspected alternative diagnosis (malignancy, infection, inflammatory arthritis); and pre-surgical planning. CT lumbar spine: used when MRI is contraindicated (pacemaker, claustrophobia); good for bony detail (spinal stenosis, facet arthropathy, spondylolisthesis); less accurate than MRI for soft tissue and disc assessment. Plain X-ray: not useful for diagnosis of disc herniation or nerve compression — may show loss of disc height and osteophytes but cannot identify nerve root compression. Electromyography (EMG) and nerve conduction studies (NCS): assess the neurophysiological integrity of the affected nerve root — identifies denervation and axonal loss; useful when the clinical picture is uncertain or when chronic neuropathy must be distinguished from radiculopathy; typically performed after 3-6 weeks from onset to allow time for electrophysiological changes to develop. Blood tests: not routinely needed for typical sciatica; ESR and CRP for suspected infective or inflammatory cause; PSA in older men (prostate cancer metastases).

Most acute sciatica resolves within 6-12 weeks with conservative management. Reassurance and education: patients should be reassured that sciatica from disc herniation almost always improves; advice to remain as active as possible rather than bed rest (evidence clearly supports activity over rest in improving outcomes). Analgesics: NSAIDs (ibuprofen 400-800 mg three times daily with food, naproxen 500 mg twice daily, or diclofenac 75 mg twice daily — most effective analgesic class for sciatica; co-prescribe PPI); paracetamol (limited evidence for neuropathic pain but safe to add for background pain relief). Neuropathic pain agents: pregabalin (75-150 mg twice daily) or gabapentin (300-900 mg three times daily) — reduce neuropathic shooting and burning pain; cause sedation and dizziness (particularly in elderly). Tricyclic antidepressants: amitriptyline 10-25 mg at night — off-label but effective for chronic neuropathic pain. Short course of oral corticosteroids: prednisolone 40-60 mg daily for 5-7 days — reduces acute nerve root inflammation; more effective for chemical radiculitis from nucleus pulposus inflammatory mediators; evidence mixed for long-term benefit. Physiotherapy: McKenzie method (directional preference exercises — repeated movements in the direction that centralises leg pain); nerve mobilisation (sciatic nerve flossing/neural tensioning — reduces adhesions around the nerve root); core muscle strengthening (transversus abdominis, multifidus); and postural correction. Spinal epidural corticosteroid injection: transforaminal or interlaminar epidural injection of corticosteroid (methylprednisolone 80 mg or triamcinolone 40 mg) plus local anaesthetic (lidocaine) under fluoroscopic or CT guidance — provides short-term (4-12 weeks) pain relief in 50-60% of patients with confirmed disc herniation; most effective for acute severe sciatica to allow engagement with physiotherapy; does not treat the underlying cause but reduces inflammation and pain. Surgery: microdiscectomy (surgical removal of the herniated disc fragment through a 2-3 cm incision with microscopic assistance): indicated for failure of 6-12 weeks of conservative treatment with ongoing significant pain and functional disability; confirmed disc herniation on MRI correlating with clinical deficit; or progressive neurological deficit (worsening foot drop). Microdiscectomy is highly effective — 85-90% of patients experience immediate relief of leg pain; mean hospital stay 24-48 hours. Laminectomy or laminotomy for spinal stenosis. Spinal fusion for spondylolisthesis. Cauda equina syndrome: emergency surgery (within 6 hours of onset for best neurological recovery).

Chronic sciatica: approximately 10% of patients develop chronic persistent leg pain lasting beyond 6 months despite conservative treatment; this leads to chronic neuropathic pain syndromes, sleep disturbance, depression (50% of chronic pain patients), and significant occupational disability. Permanent neurological deficit: progressive or unrecognised nerve root compression can cause permanent foot drop (inability to dorsiflex the foot from L5 or L4 radiculopathy) — which impairs gait; or permanent sensory loss; or chronic neurogenic pain persisting even after decompression surgery. Muscle wasting: denervation of the myotomal muscle group from prolonged nerve root compression causes atrophy of the calf, tibialis anterior, or quadriceps — affecting balance, walking, and stair climbing. Cauda equina syndrome (CES) from untreated central disc prolapse: permanent bladder dysfunction (neurogenic bladder requiring self-catheterisation — affects 50% of delayed presentations beyond 48 hours), bowel dysfunction (faecal incontinence or constipation), saddle anaesthesia, sexual dysfunction, and permanent leg weakness — CES outcomes are dramatically better with surgical decompression within 6 hours vs. beyond 24 hours. Psychological complications: anxiety, depression, fear-avoidance behaviour (catastrophising about pain — a major driver of chronification), and social isolation significantly worsen outcomes in chronic sciatica. Post-operative complications after microdiscectomy: dural tear (1-3%), infection (0.5-1%), nerve injury (0.5%), and disc reherniation (5-10%).

Core muscle strengthening and lumbar stabilisation exercises are the most evidence-based strategies for preventing recurrence of sciatica — the transversus abdominis and multifidus muscles provide dynamic stability to the lumbar spine and reduce loading on intervertebral discs; Pilates, yoga, and dedicated physiotherapy-directed core strengthening programmes reduce sciatica recurrence rates by 30-50%. Maintain a healthy body weight: obesity increases mechanical loading on lumbar discs, accelerates degeneration, and increases the force on nerve roots during activities. Adopt correct lifting technique: lift with the knees bent and back straight, keeping the load close to the body; avoid twisting while lifting. Ergonomic workplace adjustments: standing desks, lumbar-supported chairs (maintaining the natural lordotic curve), adequate monitor height, and regular positional changes reduce sustained disc pressure. Smoking cessation: smoking reduces blood supply to lumbar discs (via arterial disease), accelerating degeneration and increasing disc herniation risk — smokers have 2-fold higher risk of sciatica. Regular low-impact aerobic exercise (walking, swimming, cycling — 30 minutes daily): improves disc nutrition (discs are avascular and depend on cyclic loading and diffusion for nutrient delivery), maintains muscle strength, and reduces obesity. For individuals with previous sciatica, a maintenance exercise programme (physiotherapy-directed) significantly reduces recurrence rates. Identify and address psychosocial risk factors (yellow flags) — fear-avoidance beliefs, job dissatisfaction, and catastrophising significantly predict chronification.

Call 999 or go to A&E immediately for: any symptoms suggesting cauda equina syndrome — these constitute an emergency requiring same-day MRI and neurosurgical assessment: bilateral leg weakness or numbness; numbness or tingling in the saddle area (perineum, inner thighs, genitalia, anus); loss of bladder control — inability to pass urine (urinary retention) or losing urine without control (incontinence); or loss of bowel control. These symptoms indicate central disc prolapse compressing the cauda equina and require surgical decompression within hours to prevent permanent bladder, bowel, and sexual dysfunction. Seek urgent GP appointment (same day or next day) for: rapidly worsening or severe leg weakness (foot drop — unable to lift the front of the foot when walking); sciatica that becomes dramatically worse over 24-48 hours with new neurological symptoms; fever with severe back and leg pain (possible spinal epidural abscess or discitis). See your GP within 1-2 weeks for: sciatica lasting more than 2 weeks that is significantly affecting sleep and daily activities; or sciatica in an elderly patient (spinal stenosis common) or in a person with cancer history (metastatic disease). Physiotherapy referral is appropriate for most new sciatica without red flags — early physiotherapy within the first 2 weeks reduces chronification risk.