PURPOSE: To elucidate the effects of surgical airway correction via mandibular distraction on alterations in IGF-1 and IGBP-3 levels in micrognathic patients.

MATERIALS AND METHODS: Forty six patients with OSAS were evaluated for nonsyndromic micrognathia. Patients were restricted to those with the Pierre Robin sequence without any associated endocrine or hormonal anomalies. These patients underwent a battery of tests, including morphometric analysis, sleep studies, 3-d CT, cephalometric analysis, and measurements of IGF-1 and IGFBP-3 levels. These were compared with age-matched controls who were otherwise healthy. Measurement of weight-for-height, body fat mass, body mass index and fat-free mass was performed. Blood serum levels of IGF and binding protein were performed using RIA reagents (IGFI-RIA CT; Cis Bio; Gif sur Yvette) The study population was selected from patients who were referred to the Craniomaxillofacial Unit at the Hospital Metropolitano del Norte in Valencia, Venezuela, Cincinnati Children’s Hospital, and the Hospital Infantil de Mexico for mandibular distraction. Initial heights and weights were measured while fasting. A standard breakfast with a 600kcal bolus was administered, and then venous samples were drawn for IGF-1 and IGFBP-3. The serum was extracted from samples, centrifuged, and stored at -20 centigrade. Repeat blood samples were obtained during the polysomnography test at midnight and again at 2 months after distraction. Surgery consisted of linear distraction, callus molding after completion of planned advancement, and no fixated consolidation period.

RESULTS: Preoperative IGF levels were compared, and there was a significant reduction in both peripheral IGF-1 and IGFBP-3 in the micrognathic group. (p<0.01) There were also significant reductions in weight-for height and BMI in the apneic group. There were no other significant differences in preoperative growth indices. After distraction, the treatment group underwent rapid growth, with increased relative BMI, fat free mass, weight-for-height, and relative height. These parameters remained unchanged in the control group. Mandibular size was corrected empirically based upon airway correction parameters. There as a mean sagittal advancement of 39 mm. Both IGF-1 and IGFBP-3 increased significantly after distraction, with mean IGF-1 level increasing from 50.40ng/ml to 83.31 ng/ml, representing a 65% increase. IGFBP-3 levels increased from a mean of 2129 ng/ml to 2725 ng/ml, a 28% difference. These were both significant increases. Postoperative levels reached normal ranges in all patients tested.

CONCLUSION: Micrognathia with associated obstructive sleep apnea causes derangements in sleep patterns. Disruption of REM sleep is a known factor in abnormal cortisol and growth hormone levels. By correcting airway obstruction with distraction, both growth hormone levels and overall growth patterns are normalized. Measurement of IGF levels may provide a sensitive measurement of airway impairment, and may provide another rationale for correction of micrognathia that does not cause frank respiratory failure.