Three primitive reflexes in normal adults

Abstract

One or more of three primitive reflexes (palmomental, snout, and corneomandible) was elicited in 50.5% of 105 normal subjects in the third through the ninth decades of life. The reflexes appeared in a patterned fashion with advancing age. The palmomental reflex appeared earliest and was the most frequent reflex elicited at all ages. The snout and corneomandibular reflexes appeared at later ages and were elicited less frequently. The palmomental and snout reflexes often occurred alone, but the corneomandibular was elicited only when one or both of the other reflexes was also present. These reflexes appear to be normal phenomena in a significant proportion of the healthy population.

Usefulness of Primitive Reflexes in Demented and Non-Demented Cerebrovascular Patients in Daily Clinical Practice

“…This finding is in accordance with the literature: the occurrence of PRs has been demonstrated in healty elderly subjects, neurological patients and those with psychiatric disorders [2, 4, 7, 8, 9, 13, 14, 23, 24]. Their occurrence in normal adults has been interpreted as a normal phenomenon due to an age-related deafferentation of the brainstem nuclei and subcortical structures from ‘higher’ cortical control.…”

“…PRs are present in the neonatal period and infancy, and disappear later on as the result of cortical inhibition of brainstem activity [1, 2]. However, they may appear again in healthy elderly subjects as well as in neurological patients [3, 4, 5, 6, 7]. Their elicitability is strongly dependent on age [8, 9].…”

The Effects of Occupational Exposure to Chlorpyrifos on the Neurologic Examination of Central Nervous System Function: A Prospective Cohort Study

“…However, it is observed in approximately 25% of normal subjects, a frequency that compares favorably to our observation that 23% (12 chlorpyrifos and 13 referent subjects) of 111 subjects had palmomental reflexes at the second examination. 47,48 The reason we observed a lower frequency of palmomental reflexes at baseline (11%) is unclear, because the same neurologist examined all subjects. The frequency of palmomental reflexes at both examinations was similar in both groups, and chlorpyrifos exposure was not associated with increased frequency of a positive response.…”

Do Vietnam Veterans Suffer from Toxic Neurasthenia?

“…The neurological status of men who showed the reflex did not differ from that of men who did not. Jacobs and Gossman (1980) have replicated this finding by eliciting the reflex in 37% of normal volunteers. McDonald et ul.…”