The accuracy of subjective clinical assessments of the patellar reflex

Introduction: Measurement precision and accuracy of spinal reflexes plays an essential role in the clinical neurological examination. Reflexes are conventionally assessed either electromyographically or with rating scales. In this study we compared objective kinematic T-reflex and subjective assessments of patellar reflexes in 15 normal healthy subjects. Methods: Randomized recordings of objectively quantified reflexes were rated by 24 medical students, 16 general practitioners, and 12 neurologists, using a visual analog scale and the NINDS and Mayo clinical reflex scales. Results: For all groups of raters, Spearman rank correlations showed that subjective ratings significantly correlated with change of knee angle (R² = 0.72-0.79, P < 0.001) and maximum T-reflex amplitude (R² = 0.84-0.94, P < 0.001). Stepwise multiple regression analysis showed that all subjective rater groups relied most on the change of knee angle to assess the reflex. Conclusions: These findings show that subjective assessments of reflexes using reflex rating scales correlate strongly with biomechanical and electromyographic measures.