Diagnostic performance of the medial hamstring reflex in L5 radiculopathy.

Background: An avalanche of literature exists on almost every aspect of lumbar disc pathology but very limited studies have quantified the diagnostic performance of elements of clinical examination in predicting disc level, meticulously collated the reflex changes in lumbar disc herniation (LDH) as well as assessed the diagnostic performance of the medial hamstring reflex (MHR). Our study underscores the diagnostic performance of the MHR in L5 radiculopathy comparing its diagnostic power to that of the knee and ankle reflexes.

Methods: One hundred consecutive patients operated for de novo LDH in our department between January and December 2011 were prospectively followed-up. A nested case control study was designed from our cohort to assess the performance of the MHR in L5 sciatica. All patients were examined by two independent examiners pre-operatively for the MHR and the results collated and correlated to MRI and intra-operative findings.

Results: The MHR has a diagnostic performance intermediate to that of knee and ankle reflexes. The percentages correctly classified were respectively: 86%, 79% and 67% for the knee, MHR and ankle reflexes. The MHR is highly precise with an intra-rater reliability of 100% and inter-rater repeatability of above 90% and test-retest reproducibility of 100%.

Conclusion: The MHR hitherto described as elusive has a high diagnostic performance and is a valid neurologic test that should be included in the routine neurologic examination of patients with suspected L5 radiculopathy.