Quantitative computed tomographic scan and polysomnographic analysis of patients with syndromic midface hypoplasia before and after Le Fort III distraction advancement.

BACKGROUND Distraction advancement has been advocated for treatment of obstructive sleep apnea associated with congenital midface hypoplasia. The purpose of this study was to relate changes in maxillary position to changes in obstructive sleep apnea measures on polysomnography in a consecutive series of patients. METHODS Among 26 syndromic pediatric patients undergoing Le Fort III distraction over a 5-year period, 15 had documented obstructive sleep apnea with an apnea hypopnea index greater than 5. Linear and angular displacement of key bone landmarks were measured using quantitative computed tomographic scan analysis before and after distraction. Differences of linear and angular movements of maxillary landmarks were tested between those patients with improvement of obstructive sleep apnea (apnea hypopnea index <5) after treatment, and those with no improvement. RESULTS Mean postoperative apnea hypopnea index was 9.5 (range, 2.1 to 22.7). Eight patients had a decrease in apnea hypopnea index following distraction (improved group) and three additional patients had resolution of symptoms but declined postoperation polysomnography. Four had no improvement or worsening of apnea hypopnea index (no improvement group). Comparison of changes in maxillary position between the improved group and the no improvement group revealed no significant difference in magnitude or direction of linear displacement of key landmarks. Postdistraction change in sella-nasion-point A angle was the only measure significantly (p = 0.02) greater in the improved group. CONCLUSIONS Based on the authors' comparison of quantitative bone measurements and associated polysomnography changes, an angular increase in sella-nasion-point A angle on presurgical planning of maxillary movement for the treatment of sleep apnea may be more important than absolute linear changes in maxillary position alone.