EFFICACY OF A HERBST MANDIBULAR ADVANCEMENT DEVICE IN OBSTRUCTIVE SLEEP-APNEA

Treatment options for obstructive sleep apnea (OSA) may involve potential side effects or discomfort; nasal continuous positive airway pressure (CPAP) may not be tolerated by 25% of patients. We therefore sought to determine the efficacy of mandibular advancement as a treatment for OSA, and to investigate whether clinical and radiographic parameters can predict the response to this treatment. Sixteen male and 3 female subjects with documented OSA who had failed or been unable to tolerate nasal CPAP underwent baseline polysomnography and cephalometry, and were then fitted with a removable Herbst appliance to achieve forward mandibular advancement during sleep. All subjects then underwent a second cephalometric evaluation and polysomnography with the appliance in place. Fourteen of 15 subjects demonstrated significant improvement in the degree of OSA, based on the apnea-hypopnia index (AHI) (34.7 +/- 5.3 to 12.9 +/- 2.4 events/h, p < 0.002). Comparison of pre- and posttreatment cephalometric values revealed no significant change in the posterior airway space (PAS) despite a reduction in mean AHI. There was a significant decrease in the mandible-hyoid distance (MP-H) with treatment for the group as a whole. When the study population was evaluated on the basis of a successful response to mandibular advancement (posttreatment AHI < 10), the baseline MP-H was found to be significantly shorter in the responders than in nonresponders. MP-H after mandibular advancement was likewise shorter in responders than in nonresponders. In addition, the soft palate length (PNS-P) showed a significantly greater shortening in responders after treatment. This suggests that the mechanism of treatment by mandibular advancement is more complex than a simple increase in airway caliber by anterior advancement of the mandible and tongue. Stepwise regression of baseline polysomnographic and cephalometric values allowed formulation of an equation predicting AHI after treatment. Temporary mandibular advancement is a useful modality to treat OSA. Prospective studies are needed to validate the ability to predict response to mandibular advancement on the basis of baseline polysomnographic and cephalometric indices.