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

Treatment options for obstructive sleep apnea (OSA) may involve potent ial side effects or discomfort; nasal continuous positive airway press ure (CPAP) may not be tolerated by 25% of patients. We therefore sough t to determine the efficacy of mandibular advancement as a treatment f or OSA, and to investigate whether clinical and radiographic parameter s can predict the response to this treatment. Sixteen male and 3 femal e subjects with documented OSA who had failed or been unable to tolera te 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 se cond cephalometric evaluation and polysomnography with the appliance i n 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 pos ttreatment cephalometric values revealed no significant change in the posterior airway space (PAS) despite a reduction in mean AHI. There wa s a significant decrease in the mandible-hyoid distance (MP-H) with tr eatment for the group as a whole. When the study population was evalua ted on the basis of a successful response to mandibular advancement (p osttreatment AHI < 10), the baseline MP-H was found to be significantl y shorter in the responders than in nonresponders. MP-H after mandibul ar advancement was likewise shorter in responders than in nonresponder s. In addition, the soft palate length (PNS-P) showed a significantly greater shortening in responders after treatment. This suggests that t he mechanism of treatment by mandibular advancement is more complex th an 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 mod ality to treat OSA. Prospective studies are needed to validate the abi lity to predict response to mandibular advancement on the basis of bas eline polysomnographic and cephalometric indices.