Plantar reflex amusement

Every century-old truism of clinical neurology is worthy of critical review. But not every critical review is worthy. Miller and Johnston’s¹ kappa statistical demise of the Babinski sign invites the prescription of C.R.A.P. (Circular Reasoning or Anti-intellectual Pomposity) detectors.² In regard to upper motor neuron impairment (UMNI), they test the competitive reliability in the neurologic examination between elicitation of a hyperactive spinal reflex and impaired performance of a voluntary motor task. Validation is by correlation with the gold standard deficient performance of another voluntary task. The three phenomena are 1) extensor plantar reflex (Babinski sign), 2) slowed foot tapping, and 3) leg weakness.

The standard physical examination is a menu with varied normative standards, some quantitative, like body temperature. For each organ/system the data range from passive anatomic/physiologic observation to active functional tests/tasks that require varying degrees of conscious cooperation. Thus for cardiac function, routine observations may include systolic and diastolic arterial pressure, recumbent and standing, pulse rate and regularity, respiratory rate, pedal edema, and auscultation sounds of turbulent flow and valvular dysfunction. But there is no simple bedside quantitative measure of cardiac …