Influence of Maxillary Constriction on Nasal Resistance and Sleep Apnea Severity in Patients With Marfan's Syndrome* Peter A. Cistulli, MBBS, PhD; Glenn N. Richards, MBChB; Richard G. Palmisano, BDS, MDSc; Gunnar Unger, MSc; Michael Berthon-Jones; MBBS, PhD; and Colin E. Sullivan, MBBS, PhD Background: Marfan's syndrome is associated with a high prevalence of obstructive sleep apnea (OSA). As this syndrome is associated with a characteristic constricted maxilla and high-arched pal- ate, we reasoned that nasal airway constriction and resultant high nasal airway resistance (NAR) may contribute to the development of OSA. Therefore, the aim of this study was to measure NAR in pa- tients with Marfan's syndrome. In addition, we aimed to examine the influence of maxillary morphology on both NAR and the severity of OSA. Method: We measured NAR in 13 consecutive patients with Marfan's syndrome and 13 control sub- jects. NAR was measured by posterior rhinomanometry, and expressed as the inspiratory resistance at a flow of 0.5 Us. Dental impressions were taken to evaluate maxillary arch morphology, allowing measurement of the following distances: intercuspid (lCD ), interpremolar (IPD), intermolar (IMD), and maximum hard palate height (MPH). Ten of the patients and four of the control subjects had previously undergone noctumal polysomnography. Results: Mean NAR for the Marfan group was more than twice that in the control group (7.7:±:1.2 vs 2.9±0.4 em H20/1Js; p<0.005). The patients also had marked constriction of the maxillary arch compared with control subjects. Two of the lateral maxillary measurements were significantly inversely correlated with NAR. There were significant correlations between various maxillary arch measurements (MPH/lCD, MPHIIPD, MPHIIMD) and the apnealhypopnea index. Conclusion: These data suggest that high NAR is a common feature of Marfan's syndrome. Maxil- lary constriction with a relatively high hard palate appears to be a major reason for the high NAR. The significant correlations between indexes of maxillary constriction and sleep apnea severity suggest that maxillary morphology may play an important role in the pathophysiology of OSA in Marfan's syndrome. (CHEST 1996; 110:1184-88) Key words: hard palate; Marlan's syndrome; maxillary constriction; nasal ahway resistance; obstructive sleep apnea Abbreviations: AHI=apnea!hypopnea index; ICD=intercuspid distance; IMD=intermolar distance; IPD=interpremolar distance; MPH=maximum palate height; NAR=nasal airway resistance; OSA=ohstructive sleep apnea M arfan's syndrome, which is inherited as an auto- somal dominant trait, is defined on the basis of characteristic changes in three major connective tissue systems: the musculoskeletal, the eyes, and the car- diovascular system. 1 - 3 More recently, the skin, CNS, and respiratory system have been shown to have char- acteristic involvement. 3 Respiratory involvement is usually in the form of spontaneous pneumothorax. 3 *From the Centre for Respiratory Failure and Sleep Disorders, Royal Prince Alfred Hospital, and Department of Medicine, Uni- versity of Sydney, NSW, Australia. . Supported by a National Health and Medical Research Council of Australia Scholarship and the Australian Lung Foundation/Sen- sormedics Fellowshtp in Sleep Disorders (Dr. Cistulli). Manuscript received Dctober 4, 1995; revision accepted May 15, 1996. !Jeprint requests: Dr. Cistulli, The St. George Hospital, 36 Belgrave St, Kngarah 2217, NSW Australia 1184 We have previously reported a high prevalence of obstructive sleep apnea ( OSA) among patients with Marfan's syndrome. 4 · 5 The typical patient with OSA is a middle-aged, centrally obese male. 6 In marked con- trast, patients with Marfan's syndrome are tall, thin, and generally young. The precise mechanisms ac- counting for the high prevalence of OSA in patients with Marfan's syndrome are not certain. We have re- cently reported excessive upper airway collapsibility during sleep in this group of patients, and postulate that this relates to the known connective tissue defect of the syndrome. 7 A further possibility is that these patients have high nasal airway resistance (NAR) Clinical Investigations