Extensor Plantar Response: The Examination Technique Makes a Crucial Difference.

Sir,

I read with interest the article titled “Differentiating extensor plantar response in pathological and normal population” by Loo et al. in the AIAN journal.[1] The authors systematically studied this important question in 156 individuals and found that extensor responses were seen in 18.6% of feet of normal individuals. This included withdrawal response and Babinski response in nearly equal proportion. They must be commended for this meticulous work leading to a new observation, but some technical issues in the elicitation of the reflex are of concern:

The authors have not specified the stimulus object that was used to elicit the reflex

They have not mentioned how rapidly or slowly the stimulus was delivered. The textbook description of the test specifies that the stimulus must be delivered over 3–5 s[2]

How superficial or deep was the stimulus applied? Plantar reflex is a superficial reflex and applying deeper pressure results in elicitation of a muscular reflex

What is meant by great toe extension? Is it at interphalangeal joint or metatarsophalangeal joint of the great toe? Again, the textbook description is to observe the movement at metatarsophalangeal joint

Was tensor fasciae latae contraction looked for? Even in the absence of great toe movement, tensor fasciae latae contraction may be observed in Babinski response.

In the absence of these important details of methodology of elicitation of the reflex, it may be premature and potentially erroneous to state that Babinski sign could be elicited in such a significant proportion of healthy individuals. It would be helpful if the authors could make videos of Babinski sign in some of their normal subjects available for review in the online version of the journal.

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Conflicts of interest

There are no conflicts of interest.