Value of Babinski Sign Questioned

NEW YORK (Reuters Health) -
The Babinski sign is not a reliable tool for identifying upper motor neuron weakness and should not be part of the routine neurologic examination, say two neurologists from the University of California, San Francisco. "For the routine neurological examination, when the clinician is looking for evidence of upper motor neuron weakness, the Babinski sign is not a very useful screen, but foot tapping is," Dr. S. Claiborne Johnston, coauthor of the report in the October 25th issue of Neurology, told Reuters Health. Dr. Johnston and Dr. Timothy M. Miller tested the reliability and accuracy of the Babinski sign and the evaluation of foot tapping by 10 physicians (5 neurologists and 5 non-neurologists) who examined 10 subjects. Overall 199 independent tests were performed. Interobserver reliability was only fair for testing the Babinski sign, but it was substantial for evaluation of the rate of foot tapping, the authors report. Interobserver reliability did not differ significantly between neurologists and non-neurologists. Using the Babinski sign, physicians correctly identified the presence of weakness in 40% to 65% of evaluations, the results indicate. In contrast, slow foot tapping correctly predicted upper motor neuron weakness in 75% to 95% of evaluations. The sensitivity of foot tapping was greater than for the Babinski sign, the researchers note, but the specificity of the two signs was similar. "We found that the Babinski sign was unreliable and a poor predictor of the presence of upper motor neuron weakness," the authors conclude. "These findings are at odds with a current emphasis on testing for the Babinski sign as part of the routine neurologic examination; contrarily, foot tapping is not recommended as part of a standard neurologic examination." "Every century-old truism of clinical neurology is worthy of critical review," writes Dr. William M. Landau from Washington University School of Medicine, St. Louis, Missouri in a related editorial. "But not every critical review is worthy." He points out that Miller and Johnston evaluated the plantar reflex, an involuntary physiologic test, which is quantitatively different and can not properly be compared with foot tapping, a voluntary task. "Most established neurologists will have difficulty changing their thinking about it," Dr. Johnston commented. "Old ideas die hard." "As physicians, we spend hours on physical examination and this profoundly affects healthcare costs," Dr. Johnston said. "It is no longer acceptable to rely on expert opinion and physiological arguments to justify performance of components of the physical examination. We must work toward developing the evidence to show these components actually add value. Our work must be based on science and not on respect for traditions." "Rather than discarding or de-emphasizing the plantar reflex (Miller and Johnston) or concluding that such a study is junk science (Landau), this study and editorial should prompt clinicians, educators, and researchers to work together to define how elements of the neurological examination (including the plantar reflex) are used in clinical practice, and to determine how they can be properly assessed and compared with other examination approaches," writes Dr. Robert Holloway in a separate commentary.

Neurology 2005;65:1147,1150-1151,1165-1168.
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