What is sciatica?

What is Sciatica?

Sciatica is defined as pain radiating down the leg below the knee in the distribution of the sciatic nerve, suggesting nerve root compromise due to mechanical pressure or inflammation. 1 It is a symptom rather than a specific diagnosis and represents the most common manifestation of lumbar radiculopathy.

Characteristics and Definition

• Sciatica is characterized by pain that radiates from the lower back down the leg below the knee following the distribution of the sciatic nerve 2, 1
• It typically affects the buttock and lateral thigh before extending below the knee into the foot and toes 1
• Both inflammation and compression of the nerve root are important factors in causing symptomatic sciatica 3
• The term "sciatica" is increasingly considered archaic and imprecise; "spine-related leg pain" is now recommended as a more appropriate umbrella term 4

Causes

• Herniated lumbar disc is the most common cause (90% of cases occur at L4/L5 and L5/S1 levels) 2, 5
• Other potential causes include:
  • Spinal stenosis causing compression of nerve roots 2
  • Piriformis syndrome (compression of the sciatic nerve by the piriformis muscle) 1
  • Less common extraspinal causes along the course of the sciatic nerve after it exits the sacral foramen 6

Clinical Presentation and Diagnosis

• Key clinical features include:

  • Pain radiating below the knee in a typical lumbar nerve root distribution 2
  • Positive straight-leg-raise test (91% sensitivity, 26% specificity for herniated disc) 2, 1
  • Positive crossed straight-leg-raise test (29% sensitivity, 88% specificity) 2, 1
  • Neurological deficits may include weakness, sensory changes, or diminished reflexes in the affected nerve root distribution 2

• Diagnosis is primarily based on history and physical examination 3

• Imaging is generally not required in the first 6-8 weeks unless there are red flags suggesting:

  • Cauda equina syndrome (urinary retention has 90% sensitivity) 2
  • Cancer (history of cancer has positive likelihood ratio of 14.7) 2
  • Infection 2
  • Severe or progressive neurological deficits 2

Clinical Course and Management

• The natural course of acute sciatica is generally favorable, with most patients improving within 2-4 weeks with or without treatment 5

• Initial management (first 6-8 weeks) should be conservative 3:

  • Remain active rather than resting 3
  • Physical therapy and exercise therapy 1
  • Pain management with analgesics 3
  • Spinal manipulation by appropriately trained providers 1

• For chronic sciatica, effective therapies include:

  • Exercise therapy 1
  • Acupuncture 1
  • Massage therapy 1
  • Cognitive-behavioral therapy 1
  • Spinal manipulation 1

• Surgical intervention (discectomy) should be considered when:

  • Severe symptoms persist after 6-8 weeks of conservative treatment 3, 5
  • There are progressive neurological deficits 2
  • Cauda equina syndrome is present (medical emergency) 1

Important Clinical Considerations

• Distinguish radicular pain (true sciatica) from referred pain from the lower back, as they have different treatment approaches 3
• Be alert for "red flag" symptoms suggesting cauda equina syndrome, which requires emergency evaluation 1
• Pain intensity can vary throughout the day and is influenced by body position and movement 1
• Patient preference is an important factor in clinical management decisions, especially regarding surgical versus conservative approaches 5