Getting Toes To Go Up
Abstract & Commentary
By Michael Rubin, MD, FRCP(C), Professor of Clinical Neurology, Weill Cornell Medical College. Dr. Rubin reports he is involved with grants/research support for Pfizer and on the speaker's bureau for Athena Diagnostics.
Synopsis: The Babinski sign continues to be a valid bed-side test for pyramidal tract lesions.
Source: Singerman J, Lee L. Consistency of the Babinski reflex and its variants. Eur J Neurol 2008;15:960-964.
Joseph Francois Felix Babinski, a French neurologist of Polish descent, first described the phenomenon of the upgoing toe to the French Biological Society in 1896. By applying a noxious stimulus to the sole of the foot (a pinprick), he noted hallux dorsiflexion contralateral to pyramidal tract lesions, even in patients unable to voluntarily extend their toes. Improvement of the technique, by firmly stroking the lateral aspect of the sole, was reported in a second paper, that same year, by the same author, in the same journal.1 Oppenheim (1902) noted that firmly stroking the medial tibia could produce the same result; Gordon (1905) demonstrated that firm calf pressure did the same; and Chaddock (1911) added his own version, labeled the external malleolar sign, that is elicited by stroking the skin inferior to the lateral malleolus. How reliable are these various techniques, both compared to each other and when used by different examiners?
Between November 2006 and March 2007, 23 inpatients with a variety of neurological disorders, most commonly stroke, and 11 non-neurological inpatients serving as controls, were examined by six neurologists who each performed the Babinski, Oppenheim, Gordon, and Chaddock maneuvers on all subjects in a blinded fashion: patients were entirely hidden behind a curtain with only their feet exposed. Written and diagrammatic instructions were given to each examiner to maintain consistency but each could use their own tools to elicit the response (e.g., end of reflex hammer, ignition key of a Bentley). Re-examination of 6 subjects was performed one week later to determine intra-observer consistency. Each neurologist interpreted his/her own findings, repeating the test as often as needed. Equivocal responses were rejected. The kappa statistic was used for statistical analysis.
Not surprisingly, the Babinski reflex demonstrated the highest inter-observer consistency, with a kappa value indicative of moderate to substantial agreement. It was followed, in order, by the Chaddock, Oppenheim, and Gordon reflexes, all of which had kappa values indicative of fair to moderate agreement. Intra-observer consistency was best achieved by the Gordon reflex, followed by the Chaddock, Oppenheim, and Babinski reflexes. Amongst all responses, the Babinski and Chaddock were the most reliable pair and would be recommended as the preferred set at the bedside.
Commentary
Read about the Babinski sign and discover its remarkable history in the Puerto Rico Health Science Journal.2 Reported in a paralyzed animal by Czech anatomist and physiologist Jiri Prochaska as early as 1784, interpreted as a spinal reflex by Hall (1833) and Brigham (1840), and associated with hemiparesis by Karl Wernicke (1874), Babinski nevertheless merits the eponym as he was the first to interpret its clinical relevance and correlate it with central nervous system pathology. As the favorite student of Charcot, this is particularly remarkable, as the teacher rarely examined his patients. He maintained that the neurological examination had little to add to the medical history; however, his pupil was exceptional at clinical observation and will forever be remembered as demonstrating the significance of physical diagnosis. "Rabbi Hanina said: From my teachers I learned much, from my colleagues still more, but from my students most of all" (Babylonian Talmud, Tractate Ta'anit 7a).
References
1. Comptes Rendus des Seances et Memories de la Societe de Biologie. 1896:48:471-472.
2. Brau C, Brau RH. Babinski's signe de l'eventail: a turning point in the history of neurology. P R Health Sci J 2008;27:103-105.
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