sciatica; lumbosacral radiculopathy; sciatic neuropathy

Etiology

• entrapment neuropathy
  • herniated disc (L5 or S1 most comon) 85%
• inflammation compromising the L5 or S1 root
• spinal cord tumor or abscess, spinal stenosis
• myofascial pain syndromes
• trochanteric bursitis
• vascular malformations
• diabetic neuropathy
• shingles
• entrapment of sciatic nerve by piriformis muscle
• endometriosis

Clinical manifestations

• pain in the lower back & hip radiating down posterior aspect of thigh, posterior & anterior aspect of leg & into foot along the distribution of the sciatic nerve
  • leg pain as severe or more severe than low back pain
• paresthesias, numbness
• hyporeflexia on affected extremity (L2, L3, L4)
  • L5, S1 lesions: reflexes seldom affected
• pain aggravated by:
  • spinal movement, i.e. bending
  • sneezing
  • coughing
  • straining
• pain on straight leg raising
  • pain below the knee at < 70 degrees
  • indicates nerve root compression at L5-S1
  • crossed straight leg raising
    • pain elicited on affected side with contralateral straight leg raising
    • specific for lumbar radiculopathy
    • not as sensitive as ipsilateral straight leg raising
• loss of sensation in a dermatomal distribution
• decreased to absent deep tendon reflexes, especially ankle jerk
• dermatomal signs & reflex changes may be absent when only a single nerve root is affected
• local muscle weakness & atrophy may be present
  • differential circumference of > 2 cm at the right versus left calf &/or thigh suggests atrophy
  • weakness of ankle & great toe dorsiflexion
• dorsiflexion at the ankle aggravates pain, plantar flexion relieves the pain
• sensory loss in foot

Laboratory

• electromyography
• sensory evoked potential

Radiology

• plain radiographs of lumbosacral spine
  • standing flexion-extension radiographs of lumbar spine if suspected lumbar spondylolisthesis
• magnetic resonance imaging to delineate anatomy of nerve root compression & herniated disc
  • adding a coronal short T1 inversion recovery (STIR) MRI sequence might help in difficult diagnostic cases (short acquisition time & low cost)
  • repeat MRI at 1 year does not distinguish reliably patients who have improved from those who have not

Differential diagnosis

• lumbar spondylolisthesis

Management

• physical therapy
  • early referral to physical therapy improves outcomes at 6 months
• lumbar spinal manipulation may be of benefit
• oral agents
  • non-steroidal anti-inflammatory agents (NSAIDs)
  • amitriptyline 10 mg PO QHS
  • glucocorticoid
    • methylprednisolone
    • prednisone for 15 days
      • start 60 mg/day, taper to 20 mg/day
      • modest improvements in function
      • no improvement in pain
  • gabapentin
    • non-inferior to epidural steroid injection
    • no randomized trials
  • pregabalin (Lyrica) does not improve pain of sciatica
• parenteral agents
  • epidural steroids
    • of no value; of value [NEJM Knowledge+]
    • consider if associated with herniated disc
    • small short-term benefit not clinically significant
    • no long-term benefit; no benefit > 6 months
    • uncertainty about which patients might benefit
    • risks likely exceed benefits
    • may be treatment of choice if renal insufficiency, physical therapy of no benefit & surgery not an option [NEJM Knowledge+]
  • nerve root injections under fluoroscopic guidance
    • betamethasone plus bupivicaine
  • trigger point injection with bupivicaine
  • etanercept no better than epidural steroids or saline
  • pulsed radiofrequency, delivered into the back with a thin needle (anesthesia not required)
    • relief of back pain & sciatica pain >= 1 year
• surgery for disk herniation & nerve root impingement/compression
  • diskectomy may have initial benefits that decline with time
    • at 1 year, surgery comparable to conservative management for sciatica due to disc herniation
  • consider microdiskectomy if documented nerve-root compression with persistent sciatic pain for 4-12 months
  • consider spinal cord stimulation if persistent pain after surgery
    • a closed-loop spinal cord stimulator that measures & adjusts to neural response is associated with greater pain reduction compared with a fixed-output, open-loop system at 3 & 12 months
• prognosis:
  • 50-70% of patients spontaneously improve within 4 weeks

More general terms

• radiculopathy
• sciatic neuropathy

More specific terms

• lumbosacral radiculoplexus neuropathy

Additional terms

• low back pain (LBP)
• sciatic nerve
• straight leg raising (SLR)