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Difficulty: HardPhysical Examination Findings

An occupational medicine physician evaluates a 42-year-old warehouse worker who developed acute-onset, severe lower back pain after lifting a heavy crate the previous day. The pain radiates down the posterior aspect of the right thigh and calf to the lateral aspect of the foot. The patient denies any history of malignancy, recent weight loss, fever, or bowel and bladder incontinence. The physician suspects an acute lumbosacral disc herniation and wishes to use bedside maneuvers to clinically confirm the diagnosis, aiming to avoid immediate magnetic resonance imaging. Which of the following elicited physical examination findings, if present, demonstrates the highest specificity for confirming this patient's suspected diagnosis?

  1. Exacerbation of the right-sided radiating leg pain when the asymptomatic left leg is passively elevatedAnswer
  2. B
    Reproduction of the right-sided radiating leg pain when the symptomatic right leg is passively elevated to 45 degrees
  3. C
    Alleviation of the right-sided radiating leg pain when the patient flexes the lumbar spine while in a seated position
  4. D
    Diminished sensation to pinprick over the dorsum of the right foot and the first web space
  5. E
    Focal point tenderness upon deep palpation of the right lower lumbar paraspinous musculature

Answer

The correct physical examination finding is the exacerbation of the right-sided radiating leg pain when the asymptomatic left leg is passively elevated (Crossed Straight Leg Raise).
The correct answer identifies the crossed straight leg raise. When elevating the asymptomatic leg causes radiating pain down the symptomatic leg, it indicates central disc herniation or severe nerve root irritation. Because very few other pathologies cause this contralateral neural tension sign, it boasts a specificity of approximately 90%, making it the most reliable physical examination maneuver listed to confidently rule in a lumbosacral disc herniation.

Step-by-Step Solution

1
Analyze the patient's clinical presentation.
The patient has acute, unilateral, radiating lower back pain following a lifting injury, without red flag symptoms.
This presentation is classic for a lumbosacral radiculopathy (sciatica), most commonly caused by an acute herniated nucleus pulposus at the L4-L5 or L5-S1 levels.
2
Evaluate the clinical utility of diagnostic bedside maneuvers.
The physician needs a physical examination maneuver with high specificity to 'rule in' the diagnosis of a herniated disc.
Accurate bedside diagnosis prevents the unnecessary utilization of costly imaging modalities like MRI in the acute setting when red flags are absent.
3
Compare the statistical properties of the physical examination findings provided in the options.
The standard straight leg raise (symptomatic leg) is sensitive (~90%) but not specific (~40%). The crossed straight leg raise (asymptomatic leg) is highly specific (~90%) but less sensitive (~25%).
Because the physician is specifically looking for the highest specificity to confirm (rule in) the suspected diagnosis, the crossed straight leg raise is the statistically superior clinical finding.

Key Concept

The crossed straight leg raise (Fajersztajn sign) has high specificity for identifying lumbosacral nerve root compression by a herniated disc, whereas the standard straight leg raise has high sensitivity but low specificity.
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Physical Examination Findings

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