Kinematic and kinetic analysis of the inter- and intra-applicator assessment of the Babinski reflex

The first aim was to quantify variability in the mechanical technique used by neurologists to elicit the Babinski reflex. The second aim of the study was to assess if the mechanical technique is an important determinant of the subsequent reflex response.

In this study, twelve neurologists elicited the Babinski reflex five times on the same foot of the same participant using a special reflex hammer which recorded the force and duration of the stroke. Hallux movement, tibialis anterior maximum EMG amplitude and pain felt by the participant for each stroke were recorded.

A large inter- and intra-applicator variability was shown amongst the neurologists. The change in hallux angle was significantly correlated with the duration of the stroke (R(2)=0.18, P<0.01), maximum (R(2)=0.14, P=0.01) and average (R(2)=0.17, P<0.01) force used to elicit the reflex. No correlations were shown between the hammer forces and duration and the maximum amplitude of the tibialis anterior. Significant correlations were shown between the pain score and the maximum (R(2)=0.15, P<0.01) and average (R(2)=0.17, P=0.001) force used to elicit the Babinski reflex.

These results indicate that there was substantial variation when performing the Babinski reflex test within and between neurologists which could lead to differences in the resultant reflex and therefore may affect subsequent diagnoses.