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|Year : 2018 | Volume
| Issue : 5 | Page : 1377-1380
Accuracy and reliability of Babinski sign versus finger and foot tapping in the diagnosis of corticospinal tract lesions
Prabhakar T Appasamy, Teddy A Dan, Vedavati Bandyopadhyay, Vivek Mathew, Visalakshi Jeyaseelan, Suresh Babu, Sanjith Aaron, Mathew Alexander
Department of Neurology, Christian Medical College, Vellore, Tamil Nadu, India
|Date of Web Publication||17-Sep-2018|
Dr. Prabhakar T Appasamy
Department of Neurology, Christian Medical College, Vellore - - 632 004, Tamil Nadu
Source of Support: None, Conflict of Interest: None
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
Key Message: The validity and reliability of the finger and foot tapping test in the clinical diagnosis of corticospinal lesions is more than that of the Babinski sign.
|How to cite this article:|
Appasamy PT, Dan TA, Bandyopadhyay V, Mathew V, Jeyaseelan V, Babu S, Aaron S, Alexander M. Accuracy and reliability of Babinski sign versus finger and foot tapping in the diagnosis of corticospinal tract lesions. Neurol India 2018;66:1377-80
|How to cite this URL:|
Appasamy PT, Dan TA, Bandyopadhyay V, Mathew V, Jeyaseelan V, Babu S, Aaron S, Alexander M. Accuracy and reliability of Babinski sign versus finger and foot tapping in the diagnosis of corticospinal tract lesions. Neurol India [serial online] 2018 [cited 2019 May 20];66:1377-80. Available from: http://www.neurologyindia.com/text.asp?2018/66/5/1377/241370
The plantar response is an important part of the complete neurological examination. It was first described by Joseph Babinski in 1896. The pathological response of the plantar reflex is well-known by its eponym “Babinski sign,” and is characterized by the dorsiflexion of the big toe and recruitment of the extensor hallucis longus muscle. The Babinski sign has been one of the most valued 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.,,, This variation has been explained by the varying levels of clinical experience, clinical expertise, and available clinical information.,,,,, Hence, alternative clinical methods to elicit the plantar response and alternate clinical signs have been attempted to increase agreement in the diagnosis of CST lesions., Slowness of movements in the extremities and loss of dexterity are well-recognized signs of CST lesions. Foot tapping and finger tapping (FFT) are tests used to demonstrate slowness of movement., There is emerging evidence that these tests are more reliable and sensitive than the Babinski sign in detecting CST lesions., Hence, we studied the diagnostic value of finger and foot tapping as compared to Babinski sign in detecting CST lesions and the differences in interpretation between a neurologist and medical students.
| » Materials and Methods|| |
Participants were recruited from patients presenting to the department of neurosciences of a tertiary care hospital in south India. After obtaining informed consent, three groups of participants were recruited. Group 1 – having CST lesions diagnosed based on clinical examination as well neuroimaging; group 2 – non-CST neurological illness; group 3 – normal individuals who were relatives of the patients recruited. The examiners were blinded to the allotment of groups. The participants included were more than 18 years old. Patients with joint pathologies, unconscious patients, patients unable to cooperate for the examination, and patients with motor power in the limbs of less than Medical Research Council (MRC) Grade 3 were excluded from the study.
Two medical students and a neurologist served as the examiners. The examiners did not know the history or other clinical findings before examining the participants for Babinski sign and finger and foot tapping. A complete neurological examination was done by the neurologist at the end of the testing. The plantar reflex was tested while the patient was lying in a supine position. A standardized key was used to produce an innocuous stimulus along the lateral border of the sole of the foot from the heel till the metatarsal pads. A normal response was defined as a downward movement of the great toe and flexion of the other toes. Upward movement of the big toe, fanning out of the lateral four digits, flexion of the knee, or contraction of the tensor fascia lata was taken as pathological, and thus, a positive Babinski sign. Finger and foot tapping were assessed while the patient was sitting. Finger tapping was tested by asking the patient to tap as rapidly as possible on a desk using his index and middle finger. Foot tapping was assessed by asking the patient to tap on the floor as rapidly as possible using the forefoot while the heel remained in contact with the floor. Prior to the commencement of the study, the two medical students who served as examiners were given a demonstration of the procedure and were taught the interpretation of finger and foot tapping and the Babinski sign.
Using the composite of the complete neurological examination and neuroimaging as the reference standard for the diagnosis of CST lesions, the sensitivity and specificity of finger tapping, foot tapping, and Babinski sign was calculated. The kappa statistic, which reflects the proportion of agreement between examiners that is greater than that which is expected by chance, was used as a measure of inter-observer reliability between the medical students and the neurologist for the various tests.
| » Results|| |
A total of 375 patients, 125 in each group, were included in the study. Their characteristics are presented in [Table 1]. Among the patient with CST lesions, 90 (72%) patients were men and their mean age was 47. Stroke (40%), mass lesions affecting the CST (22.4%), cervical myelopathy (16%), thoracic myelopathy (2.4%), and nonstructural lesions of the CST (19.2%) were the diseases included in the group with CST lesions. The diseases included in the non-CST neurological lesions group are presented in [Table 1]. The overall sensitivity for Babinski sign was 49.6% and specificity was 85.8%. The sensitivity and specificity for the Babinski sign as tested by the two medical students and the neurologist are presented in [Table 2]. The overall sensitivity for finger and foot tapping was 79.5% and specificity was 88.4%. The sensitivity for finger and foot tapping as tested by the two medical students and the neurologist is presented in [Table 2]. The comparison of the sensitivity, specificity, and the interobserver agreement for Babinski sign and finger and foot tapping is presented in [Table 3]. 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).
|Table 2: Comparison of the accuracy of the medical students and neurologist in the diagnosis of CST lesions using Babinski sign and finger and foot tapping test|
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|Table 3: Comparison of the accuracy and interobserver agreement of Babinski sign and finger and foot tapping test in the diagnosis of CST lesions|
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| » Discussion|| |
In our study, we found that the Babinski sign was unreliable in predicting CST lesions. In addition, its validity depended on the clinical experience of the observer. However, finger and foot tapping was much more reliable, sensitive, and specific in detecting CST lesions, which did not depend on the clinical experience or expertise of the examiner. The interobserver agreement was found to be greater with foot tapping and finger tapping (FFT) as compared to Babinski sign. The sensitivity and specificity of Babinski sign found in our study was similar to the results of Miller et al., who found that the sensitivity and specificity of Babinski sign was 35% and 77%, respectively. However, Isaza Jaramillo et al., found that Babinski sign had a low sensitivity (50.8%) but high specificity (99%). Studies examining the interobserver agreement of Babinski sign found Kappa values ranging from 0.15 to 0.73.[6-8, 15, 16] The range of Kappa values obtained can be explained partly by methodological variations as well as the differences in clinical experience and expertise. Studies that included medical students and residents have had a lower reliability than the studies that include only neurologists., Foot tapping and finger tapping are tests used to demonstrate the slowness of movement and are capable of predicting CST lesions.,,, However, the studies on reliability and validity of these tests are limited.,,, Miller et al., compared Babinski sign with foot tapping and found that the interobserver reliability was higher (kappa 0.73) and the sensitivity and specificity (86% and 84%, respectively) was greater for foot tapping. Our results show that the slowness of the speed of FFT is a sensitive and specific sign in the clinical diagnosis of CST lesions. However, slowness of finger and foot tapping can be seen in extrapyramidal disorders and joint pathologies.,, The reduction of amplitude is more suggestive of an extrapyramidal disorder whereas decrease in the speed is suggestive of a CST lesion. However, clinical expertise may be required to differentiate between the two entities. Hence, the positivity of the FFT in both pyramidal and extra-pyramidal disorders and the difficulties encountered in differentiating them will be a limitation of the FFT test. Though patients with joint pathologies were excluded from this study, it is likely that interpretation of FFT in the setting of joint pathologies will be a limitation. In this study, we used a composite of clinical signs as well as neuroimaging as the gold standard for the diagnosis of CST lesions. The clinical signs included were spasticity, pattern of weakness, loss of dexterity, and exaggerated deep tendon reflexes. Among these clinical signs, spasticity was found to have a high sensitivity and specificity in the diagnosis of CST lesions. However, because it was not part of the study design, we did not measure the interobserver reliability of spasticity.
| » Conclusion|| |
In conclusion, finger and foot tapping is a valid and reliable test in the clinical diagnosis of CST lesions. The reliability and validity of Babinski sign is variable and is dependent on clinical experience, and hence, its clinical value must not be overemphasized.
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Conflicts of interest
There are no conflicts of interest.
| » References|| |
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[Table 1], [Table 2], [Table 3]