THE CLINICAL VALUE OF THE POLLICO-MENTAL REFLEX IN NEUROPATHOLOGY

Abstract

A modification of the palmo-mental reflex of Marinesco and Radovici is reported. This modification is termed the pollico-mental reflex. The pollico-mental reflex is elicited by stroking the volar surface of the terminal phalange of the thumb with a firm pointed object, such as a Yale key, causing a brisk contraction of the mentalis muscle on the same side and sometimes on the other side as well. The sign is considered positive only if reproducible inexhaustibly. 1000 normal adults, 47 newborn infants and 962 neuropsychiatric patients were tested. None of the normal adults evinced a positive reflex. A negligible percentage of patients without disturbances of the frontal lobe showed a positive pollico-mental reflex. In contrast, 88% of the cases with affection of the frontal lobe had a positive pollico-mental reflex, as did 83% of newborn infants tested. The hypothesis is offered that the pollico-mental reflex is a pathognomonic sign of an organic lesion in the premotor area. It is suggested that the reflex may be due to insufficient inhibition in the motor cortex as a result of damage in the premotor area.