What is sciatica?

Sciatica: Definition, Causes, and Management

Sciatica is a symptom characterized by pain radiating along the sciatic nerve distribution from the lower back through the buttock and down the leg, typically below the knee and into the foot, most commonly caused by nerve root compression from a herniated lumbar disc. 1

Definition and Pathophysiology

Sciatica is not a specific diagnosis but rather a symptom complex that indicates nerve root compromise due to mechanical pressure or inflammation. Key characteristics include:

• Pain radiating from the back into the leg, typically below the knee
• Pain following a dermatomal pattern corresponding to a specific nerve root
• Pain that is often worse than any accompanying back pain
• May include sensory changes, weakness, or reflex abnormalities in the affected leg

The primary causes of sciatica include:

1. Herniated disc (most common cause - 90% of cases occur at L4/L5 and L5/S1 levels) 2, 1
2. Spinal stenosis (narrowing of the spinal canal)
3. Piriformis syndrome (compression of sciatic nerve by piriformis muscle)
4. Spondylolisthesis (slippage of one vertebra over another)
5. Tumors or infections (rare but serious causes requiring urgent evaluation) 1

Clinical Presentation and Diagnosis

Diagnosis of sciatica primarily relies on history and physical examination:

• History: Assess location, radiation, character, and timing of pain
• Physical examination:
  • Straight-leg-raise test: High sensitivity (91%) but modest specificity (26%) for herniated disc 2, 1
  • Crossed straight-leg-raise test: More specific (88%) but less sensitive (29%) 2
  • Neurological examination focusing on:
    • L4 nerve root: Knee strength and reflexes
    • L5 nerve root: Great toe and foot dorsiflexion strength
    • S1 nerve root: Foot plantarflexion and ankle reflexes 2, 1

Red Flags Requiring Urgent Evaluation

• Progressive neurological deficits
• Bladder or bowel dysfunction (cauda equina syndrome)
• Fever or recent infection suggesting spinal infection
• History of cancer, unexplained weight loss
• Severe, unrelenting pain unresponsive to conservative measures 1

Management Approach

First-Line Treatment (0-6 weeks)

• Activity: Continue normal daily activities as tolerated; avoid bed rest 1
• Medications:
  • NSAIDs as first-line pharmacological treatment
  • Muscle relaxants as adjunctive therapy for acute pain
  • Acetaminophen for patients who cannot tolerate NSAIDs 1
• Physical measures:
  • Heat application for pain relief
  • Core strengthening and flexibility exercises
  • Structured physical therapy programs 1

Second-Line Treatment (6-12 weeks)

For persistent symptoms after 6-8 weeks of conservative management:

• Imaging: MRI is preferred for patients with persistent symptoms 3
• Additional medications:
  • Duloxetine (SNRI) for persistent pain
  • Gabapentin for radicular symptoms
  • Limited use of opioids only for severe, unresponsive pain 1
• Interventional options:
  • Consider referral for epidural steroid injections
  • Spinal manipulation may provide moderate benefits 1

Surgical Considerations

Surgical evaluation should be considered for:

• Persistent severe pain despite conservative management
• Progressive neurological deficits
• Cauda equina syndrome (medical emergency) 1

Common Pitfalls to Avoid

• Misdiagnosis: "Sciatica" is often incorrectly used to describe any pain radiating from the back to the leg, but true sciatica involves nerve root compression 4, 5
• Premature imaging: Routine imaging is not recommended in the first 6 weeks unless red flags are present 1
• Prolonged bed rest: Can lead to deconditioning and delayed recovery 1
• Overreliance on opioids: Poses substantial risks with insufficient evidence for effectiveness 1
• Ignoring psychosocial factors: These are stronger predictors of outcomes than physical examination findings 2, 1
• Missing serious pathology: Cauda equina syndrome, infection, or malignancy require urgent evaluation 1

The natural course of sciatica is generally favorable, with most patients experiencing improvement within 2-4 weeks with or without treatment 3. However, proper diagnosis and appropriate management can significantly reduce suffering and prevent complications.