The "bedsheet" Babinski.

ABSTRACT

Background. Babinski's reflex (dorsiflexion of the hellus and fanning of the toes in response to planter stimulation) is a classic sign in neurology. Although typically elicited by stroking the plantar surface of the foot with a firm object, other means of obtaining the response have been described.

Methods. We assessed the frequency of the Babinski response after planter stimulation by exposing the feet by removal of the bedsheet or socks in 10 patients with neurologic disease and 10 control subjects. These results were compared with those obtained by traditional means of stimulation.

Results. We found a high correlation between the two responses (sensitivity of 80% and specifity of 90%).

Conclusion. Although this study is small and requires a larger study to verify its accuracy, it appears that simple observation of the toe response at the time that the feet are exposed frequently provides evidence of pyramidal tract dysfunction.

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BABINSKI'S REFLEX has been regarded as the most important sign in clinical neurology1 and is perhaps the best known eponym in this discipline. (2) Although the toe response to plantar stimulation had been recognized earlier, (2) the difference between normal and pathologic responses and their clinical implications were first described by Joseph Babinski in two papers published in 1896 and 1898, respectively. (3) Subsequently, many variants of the reflex have been reported. Among the names attached to these variants are those of Chaddock, Oppenheim, Bing, Gordon, Schaefer, Moniz, Strumpell, Cornell, Cleclkey, Gonda, and Allen. (1)

We were impressed with the frequency with which the characteristic features of Babinski's reflex, namely, dorsiflexion of the hallux and fanning of the toes, is elicited simply by removing the bedsheets covering a patient's feet or by removing a patient's socks. Although this "spontaneous Babinski" has been noted on similar manipulation of the feet of infants and children, (1) we believe it has not been reported in adults.

METHODS

We compared the toe response to brisk removal of the bedsheets (done in one quick motion with sheets tucked under the heels or bed) (Figure) and the removal of socks (pulled off the foot from the toes) to that of the standard method of eliciting the Babinski reflex in 10 hospitalized patients with neurologic disease and 10 control subjects. These methods permit stimulation of the soles of the feet by the moving fabric. Patients ranged in age from 25 to 81 years. Six had cerebrovascular disease, two had multiple sclerosis, one had viral encephalitis, and one had Guillain Barre syndrome.

The sign was regarded as positive if dorsiflexion of the hallux was observed after the stimulus. In the event that the response was mute or there was disagreement between the examiners, the response was recorded as indeterminate. For purposes of calculating sensitivity and specificity, all indeterminate responses observed during bedsheet withdrawal were regarded as the opposite of the Babinski response elicited by the classical method of stroking the sole of the foot.

RESULTS AND DISCUSSION

Despite that modification, a surprisingly high correlation was seen between a Babinski reflex elicited by removing bedsheets and that elicited in a classical fashion. In this small series, the sensitivity of these simple observations was 80% and the specificity was 90%, though these results need to be interpreted cautiously given the small sample size and the frequency of a false-positive sign of 10%. Although this observation was made in a small number of patients and requires a larger study to ascertain validity, it emphasizes the value of simple careful observation in the performance of the physical examination.

References

(1.) DeJong RN: Pyramidal tract responses. The Neurological Examination. Hagerstown, Md, Harper & Row Publishers, 1979, pp 451-481

(2.) Bassetti c: Babinski and Babinski sign. Spine 1995; 20:2591-2594

(3.) Sternbach G: Joseph Babinski: the phenomenon of the toes. J Emerg Med 1984; 1:263-266

RELATED ARTICLE: KEY POINTS

* Babinski's reflex has been observed on removal of bedsheets or socks.

* We performed a small study (20 subjects) to compare the response to bedsheet or sock removal with the standard method of eliciting Babinski's reflex.

* The correlation between the two methods was high; sensitivity was 80% and specificity was 90%.

From the Departments of Neurology and Internal Medicine, University of Kentucky college of Medicine, Lexington.

Reprint requests to Joseph R. Berger, MD, University of Kentucky college of Medicine, Department of Neurology, Kentucky Clinic L-445, 800 Rose St, Lexington, KY 40536-0284.