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ARTICLES: Timothy M. Miller and S. Claiborne Johnston Should the Babinski sign be part of the routine neurologic examination? Neurology 2005; 65: 1165-1168 [Abstract] [Full text] [PDF]

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Should the Babinski sign be part of the routine neurologic examination?

Steven R Brenner   (9 January 2006)

Reply from the Authors

Timothy M. Miller, MD, PhD, S. Claiborne Johnston, MD, PhD   (6 January 2006)

Should the Babinski sign be part of the routine neurologic examination?

Julien Bogousslavsky   (6 January 2006)

Should the Babinski sign be part of the routine neurologic examination?

Bhupendra O. Khatri, MD   (6 January 2006)

Should the Babinski sign be part of the routine neurologic examination?

Michael Ronthal, MBBCh, FRCP   (6 January 2006)

Should the Babinski sign be part of the routine neurologic examination?

J. van Gijn, MD, FRCP, FRCP(Edin)   (6 January 2006)

Should the Babinski sign be part of the routine neurologic examination? 9 January 2006
Steven R Brenner, Department of Neurology, St. Louis VA Medical Center 915 North Grand, St. Louis, MO 63106 Send Correspondence to journal: Re: Should the Babinski sign be part of the routine neurologic examination? SBren20979{at}aol.com Steven R Brenner	I read the article by Miller and Johnston with interest. [1] The plantar response is a reflex which involves not only the toes but all the muscles which shorten the leg. With lesions of the pyramidal system, flexion synergy may become disinhibited and the extensor hallucis longus muscle is recruited into the flexion reflex of the leg which is the sign of Babinski. A true Babinski sign should be clearly distinguished from upgoing toes which may not always be a part of the flexion synergy. [11] Correct interpretation of the plantar response depends only to a small degree on the method or site of stimulation of the foot; the response in the entire leg must be assessed. [11] Van Gijn interpreted the plantar response utilizing films of equivocal toe movements. Reports vary among neurologists so it is difficult to interpret when the history and the rest of the neurological examination are presented but conclusions regarding the Babinski sign conflict. [12] The methods utilized during Miller et al's study indicated the foot primarily was examined, and did not mention the examination of the entire leg in assessing for Babinski’s sign. In cases of spinal cord transaction and hemiplegia, there may be no toe tapping at all, while Babinski’s test is almost always positive in such a condition except during initial spinal shock when it may be absent. The toe tapping test is reliable in indicating abnormality and should be incorporated into the usual neurological exam. A strong Babinski sign is often associated with neurological impairment and can be regarded as a “red flag” requiring further investigation or explanation. As such, it should be included in the neurological examination when severe dysfunction of the nervous system is suspected. References 11. Van Gijn J. The Babinski reflex. Postgrad Med J. 1995; 71: 645-648. 12. Van Gijn J, Bonke B. Interpretation of plantar reflexes: biasing effect of other signs and symptoms. J Neurol Neurosurg Psychiatry. 1977; 40: 787-789. Disclosure: The author reports no conflicts of interest.
Reply from the Authors 6 January 2006
Timothy M. Miller, MD, PhD, University of California, San Diego 9500 Gilman Drive, MC 0670; La Jolla, CA 92093-0670, S. Claiborne Johnston, MD, PhD Send Correspondence to journal: Re: Reply from the Authors timiller{at}ucsd.edu Timothy M. Miller, MD, PhD, et al.	We demand rigorous science to justify most diagnostic studies and treatments. The same level of evidence should be required to justify specific components of the neurological examination. Relying on aphorisms from legendary neurologists or on expectations based on pathophysiological arguments is unscientific. In the end, any test should withstand rigorous empirical testing. Only by careful study of the reliability and the utility of different parts of the examination will we identify the most useful components, especially for non-neurologists who frequently do not perform the complete neurological examination. Our study of the Babinski sign and foot tapping [1] poses a practical question. As the Babinski sign and foot tapping are typically practiced, what is the reliability and accuracy of these two signs? When physicians were blinded to the history and the rest of the examination, we found that the Babinski sign was unreliable and a poor predictor of upper motor neuron weakness. Side-to-side comparison of rate of foot tapping was more reliable and more sensitive and specific. In order to evaluate the utility of the plantar response as it is performed by clinicians, we did not issue instructions regarding its interpretation or supervise how the sign was performed. We agree with Dr. van Gijn, one of the first to evaluate the sign, that interobserver variation would likely be improved by rigorously defining criteria for the Babinski sign before doing the study, but this is not is how the test is typically performed. In addition, the test may work very well in the hands of master clinicians or when used for purposes other than screening for upper motor neuron weakness. Our study does not impugn the sign itself; just the sign the way it is currently practiced by a sample of physicians. However, we were surprised to find that the sign was no more useful as practiced by neurologists compared to non-specialists. If training were the sole cause of poor reliability, we would have expected some increase in reliability among the neurologists. Even if training were the problem, wouldn’t it be more practical to focus attention of clinicians on signs that are more easily taught and reliably used? We acknowledge that the lack of comparison of the Babinski from side to side may have decreased its accuracy, though this should not have affected its reliability. We also acknowledge that the Babinski sign and foot tapping are testing entirely different anatomic pathways; we are comparing them only as signs of upper motor neuron weakness in awake patients. We agree with Dr. Ronthal that it is likely that a Babinski sign does not accompany some upper motor neuron syndromes. Our study is consistent with this point. However, our study also suggests that a group of physicians testing the same group of patients may not agree on who has a positive Babinski sign since the reliability was poor. We are intrigued by the modified Babinski sign reported by Dr. Khatri and look forward to seeing it studied systematically with blinding. Dr. Bogousslavsky has examined an impressive number of healthy controls and provides a valuable perspective. However, it is difficult to extrapolate his personal experience with young, healthy males to that of other physicians and the more typical, older neurology patient population. We agree with Dr. Brenner that the Babinski sign should remain an important tool for expert neurologists, especially in patients that are unable to participate in the examination, where the sign may serve as a “red flag.” However, our study suggests that busy clinicians (especially non-neurologists) might do better to focus on other aspects of the neurological examination, such as speed of foot tapping. In clinical practice, how often is the plantar response retested until it agrees with the expectation in a particular patient? Why is the sign so difficult to teach our residents and students? Why do we tolerate equivocal responses and create complex rules to differentiate withdrawal from a true Babinski sign? Bias is everywhere. Disclosure: The authors report no conflicts of interest.
Should the Babinski sign be part of the routine neurologic examination? 6 January 2006
Julien Bogousslavsky, University Hospital Lausanne 1011, Switzerland Send Correspondence to journal: Re: Should the Babinski sign be part of the routine neurologic examination? julien.bogousslavsky{at}chuv.ch Julien Bogousslavsky	Iconoclastic studies are necessary and useful when they force clinicians to revisit routine practices. As a remnant of the rapidly extinguishing species of the 20th century "neurology clinician", I was surprised by Miller and Johnston's article. [1] However, I concluded that this article supports the high standard neurological examination. As Landau points out in the accompanying editorial [9], "I have too often observed bizarrely faulty performance by house officers, medical and neurologic (…) "of the plantar reflex, not uncommonly resembling to an attempt at surgical exploration of the foot sole. It may be important to follow Babinski's instructions, although written in French, to obtain a Babinski sign. As a lieutenant-colonel in the Swiss army, I conducted a prospective, "epidemiological" study of the plantar reflex in 3850 men aged 18 to 19 years. [10] After observing close to 8000 healthy feet, I concluded that a Babinski sign was never present in normal young, subjects (except in the newborn). Yes, a Babinski sign, performed lege artis, is always pathological! But as Baudelaire once said "art is long, and time is short". Reference 9. Landau WM. Plantar reflex amusement. Miruse, ruse, disuse, and abuse. Neurology 2005;65:1150-1151. 10. Bogousslavsky J. The Babinski sign. Practical Neurology 2002;2:126. Disclosure: The author reports no conflicts of interest.
Should the Babinski sign be part of the routine neurologic examination? 6 January 2006
Bhupendra O. Khatri, MD, Center for Neurological Disorders 2801 W. KK River Parkway, Suite 630, Milwakee WI 53215 Send Correspondence to journal: Re: Should the Babinski sign be part of the routine neurologic examination? bokhatri{at}aol.com Bhupendra O. Khatri, MD	The slowness of foot tapping described by Miller et al [1] may be abnormal in a variety of neurological disorders and therefore is not a useful localizing clinical tool. The Babinski sign, if definitely present, is always an indicator of an upper motor neuron dysfunction. [8] However, it is not always an easy task to elicit a response. Sometimes the response to plantar stimulation is weak or absent and the term “equivocal Babinski sign” is frequently recorded. A modified Babinski sign as described below is easy to elicit even in patients with ticklish feet. The examiner first holds the patient’s big toe by placing the left index and second fingers on the dorsum of the toe and the thumb on the plantar aspect of the toe. The toe is gently semidorsiflexed and held in that position while the lateral plantar surface of the foot is stimulated with a blunt point object--from the heel upwards. The plantar response will cause the toe to exert plantar pressure perceived by the examiner’s thumb, whereas an extensor response is felt by the fingers. The pressure response obtained as a result of this method is striking and easily demonstrable in otherwise sensitive patients. By using this technique, I have not provoked an abnormal response in individuals who do not have CNS abnormalities. Conversely, I have successfully demonstrated the sign in those whom conventional Babinski was absent (and the CT or MRI demonstrated appropriate CNS pathology). Furthermore, the modified Babinski sign can be performed in total darkness. Acknowledgement: I thank my teacher, Dr. Enrique Bravo- Fernandez, MD who developed the modified Babinski sign while an army surgeon on active duty and passed it on to his residents. Reference 8. Nathan PW, Smith MC. The Babinski response: a review and new observations. J Neurol Neurosurg Psychiatry 1955;18:250–259. Disclosure: The author reports no conflicts of interest.
Should the Babinski sign be part of the routine neurologic examination? 6 January 2006
Michael Ronthal, MBBCh, FRCP, Harvard Medical School Beth Israel Deaconess Medical Center, 330 Brookline, Boston, MA 02215 Send Correspondence to journal: Re: Should the Babinski sign be part of the routine neurologic examination? mronthal{at}bidmc.harvard.edu Michael Ronthal, MBBCh, FRCP	The title of Miller and Johnston’s paper on the Babinski sign is provocative. [1] The upper motor neuron syndrome (weakness, spasticity, hyperrreflexia) may or may not be accompanied by a Babinski sign. The sign itself simply implies a pyramidal tract lesion and may not be associated with any of the upper motor neuron signs which are extrapyramidal in origin, so there is some truth to the statement that it cant be used to predict weakness. A lesion of the pyramidal tract in isolation results in a flaccid hemiplegia and extensor plantar response both in monkeys when the the tract is lesioned in the pyramid and in man when spasticity may follow later, perhaps because the lesion is not “clean”. [5,6] Pseudoscience contaminates the art of the clinical examination which with experience can be finely honed. Gordon Holmes wrote: “The plantar reflex is so important that the clinician should never be satisfied with failure to elicit it by ordinary means.” [7] When we use the terms “upper motor neuron syndrome” or “pyramidal syndrome” we should be precise in what we mean and our understanding of the labels. References 5. Tower SS. The pyramidal tract. Chap 6 in: Bucy PC The Precentral Motor Cortex. Iniv Illinois Press, 1944. 6. Ropper AH, Fisher CM, Kleinman GM. Pyramidal infarction in the medulla: a cause of pure motor hemiplegia sparing the face. Neurology 1979;29:91-95. 7. Holmes Gordon. Introduction to Clinical Neurology 1946. pp: 101. E&SLivingstone, Edinburgh. Disclosure: The author reports no conflicts of interest.
Should the Babinski sign be part of the routine neurologic examination? 6 January 2006
J. van Gijn, MD, FRCP, FRCP(Edin), Department of Neurology, University Medical Centre Utrecht Room G03.228, UMCU, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands Send Correspondence to journal: Re: Should the Babinski sign be part of the routine neurologic examination? jan{at}vangijn.com J. van Gijn, MD, FRCP, FRCP(Edin)	Drs. Miller and Johnston have neglected a vital methodological issue in their efforts to debunk the Babinski sign, [1] an aspect that has also been overlooked by previous detractors. In the Methods section, they describe elaborate measures to eliminate bias, but there is not a word about the criteria for a Babinski sign. The upgoing toe sign is not an oracle, but part of a released withdrawal reflex of the leg. It is often, but not always accompanied by slowed foot tapping, [2] as Drs. Miller and Johnston have confirmed. The pathophysiological background should be considered in the interpretation of the plantar reflex. [3] In brief, the following criteria should be applied: 1) the upgoing toe movement should be caused by contraction of the extensor hallucis longus muscle; 2) the movement should be accompanied by activity in other muscles that shorten the leg; 3) the response should be reproducible. It has been shown in medical students that application of these criteria improves interobserver agreement. [4] In conclusion, the study of Drs. Miller and Johnston was not about the Babinski sign, but about the level of medical education of the physicians who participated in their study. References 1. Miller TM, Johnston SC. Should the Babinski sign be part of the routine neurologic examination? Neurology 2005;65:1165-1168. 2. van Gijn J. The Babinski sign and the pyramidal syndrome. J Neurol Neurosurg Psychiatry 1978;41:865-873. 3. van Gijn J. The Babinski sign. Pract Neurology 2002;2:42-44. 4. Raijmakers PGHM, Castro Cabezas M, Smal JA, van Gijn J. Teaching the plantar reflex. Clin Neurol Neurosurg 1991;93:201-204. Disclosure: The author reports no conflicts of interest.