Lumbar Radiculopathy

Lumbar radiculopathy is dysfunction of one or more lumbar or upper sacral nerve roots, causing radiating pain in a root distribution with sensory loss, weakness or reflex change, produced by mechanical compression, inflammation or ischaemia of the root.

• Most often caused by disc herniation (age 30 to 50) or by foraminal and lateral recess stenosis from degenerative spondylosis, facet hypertrophy and ligamentum flavum thickening (age over 60).
• Less common causes: spondylolisthesis, synovial cyst, epidural abscess or haematoma, spinal tuberculosis, metastasis, lymphoma, herpes zoster, diabetic lumbosacral radiculoplexus neuropathy, sarcoidosis, Lyme disease and arachnoiditis.
• The L5 and S1 roots are affected in over 90 percent of cases; L3 and L4 radiculopathy is more common in older adults with stenosis.

• L2 to L3: pain in the anterior thigh and groin; weakness of hip flexion and adduction; reduced knee jerk in L3.
• L4: pain over anteromedial thigh, knee and medial leg; weakness of quadriceps and ankle dorsiflexion; reduced knee jerk; femoral stretch test positive.
• L5: pain in the lateral leg and dorsum of foot; weakness of great toe extension, ankle dorsiflexion and eversion, foot drop and Trendelenburg gait; no reflex change.
• S1: pain in the posterior calf, lateral foot and sole; weakness of plantar flexion (difficulty rising on tiptoe), reduced ankle jerk.
• Neurogenic claudication (stenosis): leg pain, heaviness and weakness on standing or walking, relieved by sitting or flexing forward, and with normal foot pulses.
• Provocation tests: straight leg raise, crossed straight leg raise, slump test, femoral stretch test.
• Cauda equina warning features: bilateral symptoms, saddle numbness, urinary retention or incontinence, faecal incontinence, erectile dysfunction.

• Clinical examination with myotomal, dermatomal and reflex mapping.
• MRI lumbar spine without contrast for persistent symptoms beyond 6 to 12 weeks, severe or progressive deficit, or before intervention; with contrast if infection, tumour or previous surgery.
• CT or CT myelography when MRI is contraindicated.
• Electromyography and nerve conduction studies after 3 weeks to confirm root involvement and exclude peripheral neuropathy, plexopathy and entrapment.
• Blood tests when indicated: FBC, ESR, CRP, HbA1c, vitamin B12, calcium, alkaline phosphatase, serum protein electrophoresis.
• Differentials: peripheral neuropathy, lumbosacral plexopathy, hip disease, peripheral arterial disease, motor neurone disease, common peroneal neuropathy (foot drop with preserved inversion), sacroiliac pain, myopathy.

Emergency

• Cauda equina syndrome, rapidly progressive weakness (power 3 out of 5 or less in a major muscle group), or suspected epidural abscess: same day hospital admission and urgent MRI and surgical review.

Conservative (at least 6 to 12 weeks if deficit is mild and stable)

• Remain active; avoid prolonged bed rest; short term modification of lifting; heat.
• Physiotherapy: neural mobilisation, core stabilisation, extension or flexion based exercise according to symptoms (flexion based for stenosis).
• Analgesia: ibuprofen 400 mg three times daily or naproxen 500 mg twice daily with food and omeprazole 20 mg daily for up to 2 to 3 weeks; paracetamol 1 g up to four times daily; neuropathic agents as needed: amitriptyline 10 to 50 mg at night, duloxetine 30 to 60 mg daily, gabapentin 300 mg at night titrated to 300 to 600 mg three times daily, or pregabalin 75 to 150 mg twice daily. Reduce renally excreted drugs by creatinine clearance.
• Glycaemic control in diabetes; stop smoking; weight reduction.

Injection therapy

• Epidural or selective nerve root steroid injection (for example triamcinolone 40 mg or methylprednisolone 40 to 80 mg with local anaesthetic) for radicular pain not controlled after 4 to 6 weeks; maximum 3 injections in 6 months and 4 in a year; monitor glucose in diabetes.

Surgical

• Discectomy or microdiscectomy for: disc herniation with persistent disabling radicular pain beyond 6 to 12 weeks; progressive or severe motor deficit; cauda equina syndrome.
• Decompressive laminectomy or foraminotomy (with or without fusion for instability) for stenosis with neurogenic claudication that limits walking and does not respond to 3 months of conservative treatment.

Follow up

• Review at 2, 6 and 12 weeks; re-examine power at each visit.
• Safety advice: attend urgently for new bladder or bowel dysfunction, saddle numbness, increasing weakness or bilateral symptoms.