The palmomental reflex from mechanical stimulation in normal man: normative data.

The authors report normative data on the electrical response (EMG response) recorded from the mentoneal muscles by repetitive mechanical stimulation of the palmar and dorsal surface of the hand in 23 normal adults: the palmomental reflex (PMR). An early and late response was observed in 11 cases. The PMR potentials showed great variability in latency, amplitude and duration and were present in about 70% of the subjects in whom the PMR was undetectable by visual inspection. In 3 cases the reflex was also observed contralaterally to the side of stimulation. The afferent branch of the normal PMR is constituted of impulses originating mainly from the median nerve skin and muscle receptors. Such impulses could reach facial motor nuclei either through short-(paucisynaptic) or long-loop (thalamocortical) circuits.