Validation of a Novel Provocative Examination Maneuver for the Diagnosis of Lumbar Foraminal Stenosis Through Selective Nerve Root Block Outcomes

Objective: Lumbar foraminal stenosis can lead radiculopathy in a subset of patients. Imaging findings have a high false-positive rate. The Kemp test is a provocative maneuver that has traditionally been used for diagnosing facet joint disease. However, it has shown an increased likelihood of concomitant foraminal stenosis. Thus we evaluated the diagnostic accuracy of a modified version of Kemp test (the Singh-Hartl foraminal compression test) in the diagnosis of symptomatic foraminal stenosis.Methods: Fifty consecutive patients with radiculopathy were enrolled. Participants were asked to perform the Singh-Hartl foraminal compression test, with a positive result if there was reproduction of radicular symptoms. Selective nerve root block (SNRB) was then performed at the suspected level. Visual analogue scores (VAS) were collected before and 15-minutes postprocedure. VAS improvement was calculated as a percentage. Various statistical analyses were conducted considering 2 different threshold (75% or 80% improvement in VAS).Results: Twenty-eight participants (56%) were women, with an average age of 47.3 years. L4 was most commonly involved (n=20). Using 75% improvement as the VAS threshold, the test had a sensitivity of 0.72 (95% confidence interval [CI], 0.53–0.87), specificity of 0.57 (95% CI, 0.34–0.78), PPV of 0.70 (95% CI, 0.56–0.79), and NPV of 0.60 (95% CI, 0.43–0.75). When using 80% improvement as the VAS threshold, the test had a sensitivity of 0.64 (95% CI, 0.41–0.83), specificity of 0.43 (95% CI, 0.24–0.63), PPV of 0.47 (95% CI, 0.36–0.58), and NPV of 0.60 (95% CI, 0.43–0.75).Conclusion: The Singh-Hartl maneuver exhibited moderate to strong ability to rule-in the diagnosis and a moderate ability to rule out the diagnosis of foraminal stenosis when using a threshold of 75% improvement in radicular symptoms post-SNRB. Further studies evaluating the result of this physical examination test in conjunction with severity of imaging findings are warranted.