Introduction: The Babinski sign is one of the most important clinical signs for detecting corticospinal tract (CST) lesions. However, due to variations in testing and interpretation, it has been associated with low interobserver agreement rates. In this study, the diagnostic value of finger and foot tapping in detecting CST lesions was compared to that of the Babinski sign.
Materials and methods: Three groups of participants were recruited: Group 1 - individuals having CST lesions diagnosed on the basis of clinical examination as well as neuroimaging; group 2 - individuals having a non-CST neurological illness; group 3 - normal individuals who were relatives of the patients recruited. The sensitivity and specificity of finger tapping, foot tapping, and Babinski sign were calculated.
Results: 375 patients, 125 in each group, were included. The overall sensitivity for Babinski sign was 49.6% and specificity was 85.8%. The overall sensitivity for finger and foot tapping was 79.5% and specificity was 88.4%. The interobserver agreement between the medical students and the neurologist was greater for finger and foot tapping (Kappa = 0.83) when compared to Babinski sign (Kappa = 0.45).
Conclusion: Finger and foot tapping is a valid and reliable test in the clinical diagnosis of corticospinal lesions. The reliability and validity of Babinski sign is variable and thus its ability to diagnose the manifestations of corticospinal lesions is less when compared to the finger and foot tapping test.
Keywords: Babinski sign; corticospinal tract; extra-pyramidal disorders; plantar reflex; pyramidal disorders.