The history and physical exam steer the clinician toward a diagnosis of lumbosacral pathology if radiculopathy is present, and primary clinicians are trained to search for red flag symptoms that would prompt a referral to a specialist. However, the diagnostic accuracy of history‐taking is low. Verwoerd et al. performed a cross‐sectional study investigating the ability of individual questions and a six‐question model to predict lumbosacral nerve root compression confirmed by MRI.¹ Questions pertaining to sensory loss were effective, with odds ratios of 2.31 (95% confidence interval [CI]: 1.10–4.85) for nerve root compression and 3.54 (1.64–7.64) for disc herniation. However, the six‐question model as a whole was poorly predictive of lumbosacral nerve root compression with an area under the receiver operator characteristic curve (AUC) of 0.65 (0.58–0.71) and 0.66 (0.58–0.74).

Earlier prospective studies argued that physical exam maneuvers and testing could sufficiently diagnose lumbar radiculopathy and even localize the vertebral level of pathology.² However, a subsequent Cochrane review concluded the role of diagnostic physical exam tests in lumbosacral radiculopathy was poorly substantiated after reviewing 18 studies on the subject.³ Iversen et al. performed a prospective study on the accuracy of the physical exam maneuvers recommended by the American Spinal Injury Association (ASIA) to predict nerve root impingement.⁴ They reported that no individual test was reliable at predicting the laterality or level of impingement, with low sensitivities and specificities and wide confidence intervals.

A systematic review by Wassenaar provided level I evidence on the role of MRI in diagnosing lumbosacral pathology.⁵ The pooled data calculated a sensitivity of 75% (95% CI: 65–83%) and specificity of 77% (95% CI: 61–88%) for diagnosing herniated nucleus pulposus (HNP). Likewise, for nerve root compression, two studies showed sensitivities of 81 and 92% with specificities of 52 and 100%. Importantly, clinicians must be aware that there is poor interrater agreement on MRI findings in degenerative lumbar conditions.⁶ A systematic review of the use of CT for diagnosing lumbosacral pathology concluded CT was useful for HNP but not other causes of lumbosacral radiculopathy.⁷