Perioral somesthetic sensibility: do the skin of the lower face and the midface exhibit comparable sensitivity?

Studies of the perioral somatosensory capacities of neurologically normal adults were reviewed to determine whether sensitivities within the mental and infraorbital nerve distributions are comparable. It was found that tactile detection sensitivity, spatial acuity, and sensitivity to warmth are greater on skin sites located on the midface than on the lower face. In contrast, sensitivity to direction of motion and to differences in surface texture may be greater on skin sites located on the lower face. The literature further suggests that sensitivity within the distribution of each nerve varies appreciably. For example, the vermilion of the lips exhibits considerably greater vibrotactile detection sensitivity, spatial acuity, and sensitivity to direction of motion than does the perioral hairy skin. In addition, spatial acuity is notably greater on midline structures. These findings suggest that knowledge of the patterns of spatial variations in perioral tactile sensibilities can be effectively used during neurosensory examination to select control skin sites for comparison with areas of suspected neurosensory impairment and to distinguish apparent pathological alterations in tactile sensitivity from normal regional differences that characterize the perioral complex.