Gender Base Morphological Variations of the Upper Airway Space in Adult Non-Obstructive Sleep Apnea Patients

BACKGROUND & PURPOSE:

The prevalence of Obstructive Sleep Apnea (OSA) in female is less than male with reported ratio (male/female) between 4-2:1.With aging and after menopause the incidences of OSA increases in females and the ratio narrows. The upper airway of adult non-OSA individuals has been evaluated and normal values described for reference. The objective of this study is to evaluate the morphological difference between the upper airway space of adult non-OSA male and female patients through the aging process.

METHODS:
700 DICOM files from CBCT of 350 male and 350 female individuals in orthodontic treatment were evaluated for the upper-airway-space (UAS) using 3dMDvaultus software (Atlanta, GA). Patients were otherwise healthy and did not have symptoms or history of OSA. All patients had skeletal class I or a mild class II pattern with class I malocclusion or class II malocclusion whom did not require orthognathic surgery. Patients’ age ranged from 26 to 65 categorized into seven male and seven female age groups ranging from 26-30,31-35,36-40,41-45,46-50,51-55 and 56-65. The UAS identified from PNS-hyoid and divided into retropalatal (PNS-soft palate) and retroglossal (soft palate-hyoid) space. The total volume of the UAS, the surface area at the retropalatal (RP) and retroglossal (RG) choke points and the vertical length of the UAS all measured.  

RESULTS:

The total volume of the UAS was slightly larger in all male patients. This volume decreased with age in both genders. Statistical analysis with a Student’s t Test (0.295) did not show a significant difference in the total volume between the genders. The vertical length of the UAS was longer in male patients. The vertical length remained constant in all males and increased in all females with aging. The upper airway index (height/volume) was greater for females and decreased with age. There was a statistically significance in the vertical height using the Student’s t Test (0.00). The surface area at the RP choke point was larger in all female age groups, proven statistically with a Student’s t Test (0.018). The surface area of the RP choke point decreased in both genders with aging. The ratio (female/male) of RP choke point was 1.57 at 26-30 age group and progressively decreased to 1.02 at 56-65 age group. The surface area at the RG choke point was larger in in the female age groups of 26-30 to 36-40 then the male age groups of 41-45 to 56-65. There was no statistical significance in the RG surface area choke point between the genders using a Student’s t Test (0.468). The surface area of the RG choke point decreased in both male and female with aging.

CONCLUSIONS:

There is a morphological difference in the upper airway between genders. The surface area at the RP choke point is larger and vertical length of the upper airway is shorter in the females, this decreases the resistance to airflow. In females the surface area at choke points decreases and the vertical length of the upper airway increase with age. This change correlates with the date in the literature that females are less predisposed to OSA as to their male counterparts but with increased age and after menopause the incidence of OSA in females increase and the ratio narrows.

REFERRENCE:

Kapsimalis F,et al.Gender and obstructive sleep apnea syndrome, part 1: Clinical features. Sleep 2002:25(4); 409-416.

Schendel SA,et al.Airway growth and development: A computerized 3-dimensional analysis. J Oral & Maxillofac Surg 2012,Feb.9 [Epub ahead of print].