Facial altered sensation and sensory impairment after orthognathic surgery

The aim of this study was to determine whether impairment of sensory functions after trigeminal nerve injury differs in severity among patients who report qualitatively different altered sensations. Data were obtained from 184 patients. Before and at 1, 3 and 6 months after orthognathic surgery, patients were grouped as having no altered sensation, negative sensations only (hypoaesthetic), mixed sensations (negative + active), or active sensations only (paraesthetic or dysaesthetic). Bias-free estimates of contact detection and two-point discrimination were obtained to assess, via ANOVA, whether patients in the four groups exhibited different levels of sensory impairment. Impairment in contact detection and two-point discrimination was found to differ significantly among the groups at 6 months but not at 1 month. At 6 months, patients who reported negative sensations only exhibited the greatest impairment, on average, in contact detection; in contrast, patients who reported mixed sensations exhibited the greatest impairment in two-point discrimination. The least residual impairment at 6 months was observed in patients who reported no altered sensation. It is recommended that clinical judgments regarding nerve injury-associated sensory dysfunction should not be based on threshold testing results without consideration of patients’ subjective reports of altered sensation.