Craniofacial morphology and head posture in Chinese subjects with obstructive sleep apnea

This study measured craniofacial and head posture variables from standardized lateral cephalometric radiographs in Chinese subjects with obstructive sleep apnea (OSA) referred to a university hospital. The investigation was performed in the Sleep Laboratory of the Department of Respiratory Medicine, National University of Singapore. The sample consisted of 61 Chinese male subjects, 25 with mild and 36 with moderate-to-severe OSA diagnosed using overnight polysomnographic studies. Standardized head posture lateral cephalometric radiographs were used to record linear and angular dimensions for head posture and morphology. The moderate-to-severe sample was compared with the mild group, as for ethical reasons no control group with standardized cephalometric radiographs was available. Significant differences were found between hyoid positions for the mild and moderate-to-severe samples with OPA. The hyoid was more caudally placed in the moderate-to-severe sample when measured to the mandibular border (ML; P < 0.05) and to the maxillary plane (NL; P < 0.01). No significant differences were found for other craniofacial variables measured, but the anterior cranial base was shorter, cranial base angle smaller, and gonial angle greater in the moderate-to-severe sample, but this did not reach a level of significance. There were also no significant differences between the values recorded for head posture variables, so the data for the mild and moderate-to-severe samples were pooled and compared with existing published control studies for both Chinese and white subjects. This revealed a marked increase in craniocervical angulation (P < 0.001) for the total OSA study sample for craniovertical (NSL/VER), craniocervical (NSL/OPT), and craniohorizontal (OPT/HOR) variables when compared with each of the various control groups. The study provides evidence that a more caudal hyoid bone position and greater craniocervical angulation are found in subjects with OSA