Journal of Dental Research, Vol 72, 1206-1214, Copyright © 1993 by International & American Associations for Dental Research Online Journals
Spatial and gender-dependent variations in perioral pinprick sensitivity
J. Lee and G. K. Essick
North Carolina School of Science and Mathematics, Durham 27705.
Twenty-eight right-handed young adults participated in a sensory testing
experiment to evaluate pinprick sensitivity at ten spatially matched sites
on the right and left sides of the face. Stimuli were provided by a
sharp-pointed dental explorer on which a rubber eraser had been positioned
to minimize variations in the extent to which the skin was indented.
Sharpness was defined as the magnitude at which abrupt, localized
pricking/stinging sensations were evoked. A magnitude matching procedure
was used to reduce among-subject variability in the data. Specifically,
each estimate of sharpness was adjusted (i.e., divided) by the subject's
mean estimate of the brightness of a visual stimulus. Prior to data
collection, subjects were carefully instructed on the use of a common
numerical scale for assignment of values of sharpness and brightness.
Repeated-measures analysis of variance of the adjusted estimates of
sharpness revealed a non-significant effect of gender (p > 0.4), a
highly significant effect of side (p < 0.0001), and a highly significant
effect of test site (p < 0.0001). Pinprick percepts were sharper on the
left side of the face than on the right. Moreover, the vermilion of the
upper lip exhibited the greatest sensitivity to pinprick; the vermilion of
the lower lip exhibited the least sensitivity. These results suggest that
use of a patient's sensitivity to pinprick during clinical neurosensory
examination must be undertaken in an informed manner. A conclusion of
pathological alteration in sensation can be made only after consideration
of the normal spatial variations in the percept of sharpness.
