Teaching the plantar reflex* P.G.H.M.
R a i j m a k e r s , M. C a s t r o C a b e z a s , J . A . S m a l , a n d J. v a n G i j n * *
Introduction Summary
The plantar response is a frequently performed diagnostic test in general practice. In the judgement of this response major interobserver variation and bias has been demonstrated. 1,2 In teaching the technique and interpretation of the plantar response a videotape might be particularly useful. We introduced an instructional videotape for medical students in which three main criteria for recognizing a Babinski sign were demonstrated. 3 1) There must be a contraction of the extensor hallucis longus muscle ( E H L ) . This can be reliably checked by inspection of the E H L tendon, which clearly protrudes under the skin when the muscle is active. A n upgoing big toe without E H L contraction can be produced if the foot dorsiflexes as a whole, or can be falsely suggested if the little toes go down. 2) The response should be part of a flexion synergy. The Babinski sign is part of a primitive withdrawal reflex which is seen in full degree during the first year of life and which may again include the upgoing toe response after injury of the pyramidal tract. 4 E H L contraction is therefore pathological only if it occurs synchronously with activity in other (physiological) flexor muscles of the leg. In some subjects the flexion synergy is weak, but usually the tensor fasciae latae can be seen to tighten as a reference.
The efficacy of an instructional videotape about the interpretation of the plantar response was evaluated during a two week neurological clerkship. Experimental groups saw the videotape, control groups did not. All students (n = 65) assessed plantar responses of two to four different patients. Their judgement was compared with that of one senior neurologist. Only the students who had seen the videotape showed a significant improvement in performance on a second test (t-test, t=-2.26, p=0.031). In addition, these students more frequently took account of the flexion synergy (Fisher exact test, p
R a i j m a k e r s , M. C a s t r o C a b e z a s , J . A . S m a l , a n d J. v a n G i j n * *
Introduction Summary
The plantar response is a frequently performed diagnostic test in general practice. In the judgement of this response major interobserver variation and bias has been demonstrated. 1,2 In teaching the technique and interpretation of the plantar response a videotape might be particularly useful. We introduced an instructional videotape for medical students in which three main criteria for recognizing a Babinski sign were demonstrated. 3 1) There must be a contraction of the extensor hallucis longus muscle ( E H L ) . This can be reliably checked by inspection of the E H L tendon, which clearly protrudes under the skin when the muscle is active. A n upgoing big toe without E H L contraction can be produced if the foot dorsiflexes as a whole, or can be falsely suggested if the little toes go down. 2) The response should be part of a flexion synergy. The Babinski sign is part of a primitive withdrawal reflex which is seen in full degree during the first year of life and which may again include the upgoing toe response after injury of the pyramidal tract. 4 E H L contraction is therefore pathological only if it occurs synchronously with activity in other (physiological) flexor muscles of the leg. In some subjects the flexion synergy is weak, but usually the tensor fasciae latae can be seen to tighten as a reference.
The efficacy of an instructional videotape about the interpretation of the plantar response was evaluated during a two week neurological clerkship. Experimental groups saw the videotape, control groups did not. All students (n = 65) assessed plantar responses of two to four different patients. Their judgement was compared with that of one senior neurologist. Only the students who had seen the videotape showed a significant improvement in performance on a second test (t-test, t=-2.26, p=0.031). In addition, these students more frequently took account of the flexion synergy (Fisher exact test, p
