Sciatica

“Symptoms of pain, tingling, and numbness which arise from nerve root compression or irritation in the lumbosacral spine”

Risk Factors

• Increased risk of developing sciatica:
  • Strenuous physical activity, for example, heavy lifting or jogging.
  • Whole-body vibration, for example, driving.
• Modifiable factors associated with the first onset of sciatica:
  • Smoking
  • Obesity
  • Occupational factors
  • General health

Aetiology

• A herniated intervertebral disc (90% of cases), Spondylolisthesis, Spinal stenosis.
• Cancer and infection (rare).

Pathophysiology

• Sciatic nerve L4-S3 can be damaged by pelvic tumours or fractures to pelvis or femur.
• Lesions affect the hamstrings and all muscles below the knee (> foot drop), with loss of sensation below the knee laterally

Clinical Presentation

• Unilateral leg pain radiating below the knee to the foot or toes.
• Low back pain, numbness, tingling (paraesthesia), and muscle weakness in the distribution of a nerve root (dermatome).
• Red flags:
  • Cauda equina syndrome
  • Spinal fracture
  • Cancer
  • Infection (such as discitis, vertebral osteomyelitis, or spinal epidural abscess)

Investigations

• Positive straight leg raising test, Extensor plantar response
• XRay of the lumbar spine
• CT and MRI imaging only to be requested if serious underlying pathology is suspected

Management

• Admission or urgent referral to a neurosurgeon or orthopaedic surgeon if:
  • Red flag symptoms are present
  • There is a progressive, persistent, or severe neurological deficit
• Adequate analgesia (an NSAID first-line, or codeine with or without paracetamol if an NSAID is contraindicated or not tolerated).
  • If analgesia is not effective, drugs to treat neuropathic pain can be prescribed.
• Assess the risk of back pain disability using a risk stratification tool.
  • Offer higher risk patients referral for group exercise, and/or cognitive behavioural therapy, and/or physiotherapy.
• Consider referral to low back pain specialist referral for an epidural corticosteroid/ local anaesthetic injection.
• Assessment for radiofrequency denervation, or spinal decompression if non-surgical treatment has not improved pain or function.
• Provide information about its expected time course, self-help measures, advice about staying active, resuming normal activities, and returning to work as soon as possible.

Complications

• Permanent nerve damage
• Psychosocial problems eg Anxiety, depression, and impact on family
• Loss of employment from time off work, reduced productivity