Functional Outcomes of Cleft Lip Surgery. Part IV: Between- and Within-Participant Variables Affecting Lip Vermilion Sensory Thresholds

Abstract

Compare neurosensory assessments for participants with and without a cleft lip; identify between- and within-participant variables affecting sensory thresholds on the vermilion of participants with cleft lip. A parallel group, nonrandomized clinical trial. There were 56 participants with cleft lip and 37 noncleft participants. Two-point perception and warmth and cool detection thresholds were measured on the right and left sides of the upper and lower vermilion. A cotton-tip stick, stroked across the skin, was used to identify altered sensation. Linear mixed effects modeling was used to examine the effects of between- and within-participant variables on the thresholds. Threshold values on the upper and lower vermilion were similar for cleft and noncleft participants and were unaffected by the presence of a cleft on the side tested. Participants with cleft lip who reported hyposensitive altered sensations had higher two-point thresholds on the upper lip than those who reported hypersensitivity. Participants with cleft lip who reported altered midface sensation had lower warmth detection, but higher cool detection thresholds, on the lower vermilion than participants with cleft lip who did not report altered sensation. Participants with bilateral cleft lip had lower warmth detection thresholds on the upper vermilion than participants with unilateral cleft lip. Although participants with cleft lip and noncleft participants exhibit similar thermal and two-point discrimination, on average, differences exist among subgroups of participants with cleft lip that may reflect central disturbances in the processing of somatosensory stimuli.