What are the key components of a physical exam for a patient presenting with sciatica?

Key Components of a Physical Examination for Sciatica

A comprehensive physical examination for sciatica should include neurological testing, specific provocative maneuvers, and assessment of psychosocial factors to accurately diagnose and guide treatment decisions. 1

Neurological Examination

Motor Testing

• L4 nerve root: Assess knee strength and patellar reflexes 2
• L5 nerve root: Evaluate great toe and foot dorsiflexion strength 2
• S1 nerve root: Test foot plantarflexion and ankle reflexes 2

Sensory Testing

• Evaluate distribution of sensory symptoms along dermatomal patterns 1
• Check for sensory loss in specific nerve root distributions:
  • L4: Medial calf
  • L5: Dorsum of foot, first web space
  • S1: Lateral foot, sole

Reflex Testing

• Patellar reflex (L4)
• Achilles reflex (S1)

Provocative Tests

Straight-Leg Raise Test (SLR)

• Position: Patient supine with knee extended
• Technique: Passively flex the hip while keeping knee extended
• Positive: Reproduction of the patient's sciatica between 30-70 degrees of leg elevation
• Diagnostic value: High sensitivity (91%) but modest specificity (26%) for diagnosing herniated disc 2

Crossed Straight-Leg Raise Test

• Technique: Perform SLR on the unaffected leg
• Positive: Reproduction of pain in the affected leg
• Diagnostic value: More specific (88%) but less sensitive (29%) than standard SLR 2

Additional Assessment Components

Spinal Mobility

• Assess range of motion of the lumbar spine
• Note any movement limitations or pain provocation with movement

Screening for Red Flags

• Cauda equina syndrome: Check for urinary retention, saddle anesthesia, bilateral leg weakness 2
• Cancer: History of cancer, unexplained weight loss, failure to improve after 1 month, age >50 years 2
• Infection: Fever, intravenous drug use, recent infection 2
• Vertebral fracture: Older age, history of osteoporosis, steroid use 2

Psychosocial Assessment

• Evaluate psychosocial factors as they are stronger predictors of outcomes than physical examination findings 2
• Screen for depression, passive coping strategies, job dissatisfaction, disability levels, disputed compensation claims, or somatization 2

Differential Diagnosis Considerations

Distinguishing Radiculopathy from Peripheral Neuropathy

• Radiculopathy: Typically unilateral, dermatomal distribution, often associated with disc herniation 1
• Peripheral neuropathy: Usually bilateral and symmetrical with "stocking-glove" distribution 1

Extraspinal Causes

• Consider piriformis syndrome which can compress the sciatic nerve outside the spinal canal 1

Common Pitfalls to Avoid

1. Overreliance on imaging: MRI findings often don't correlate with symptoms, with high rates of both false-positive and false-negative findings 1

2. Assuming all leg pain is radicular: Consider peripheral neuropathy when symptoms are bilateral and symmetrical 1

3. Missing red flags: Failure to identify serious underlying conditions requiring urgent evaluation 1

4. Neglecting psychosocial factors: These are stronger predictors of outcomes than physical examination findings 2

5. Incomplete neurological examination: Failing to systematically assess all relevant nerve roots can lead to misdiagnosis 2

The physical examination for sciatica should be thorough and systematic, focusing on neurological assessment and provocative tests while screening for red flags and psychosocial factors that may influence outcomes.