[Craniofacial anatomical characteristics of patients with catathrenia]

Objective: To analyze whether the upper airway of patients with catathrenia has obstructive manifestations using nasal resistance, craniofacial, and upper airway imaging methods, which could benefit the exploration of the etiology and treatment options. Methods: From August 2012 to September 2019, a total of 57 patients with catathrenia in the Department of Orthodontics at Peking University Hospital of Stomatology were included in the study, including 22 males and 35 females, aged (31.1±10.9) years, with a body mass index of (21.7±2.7) kg/m². All the patients were diagnosed by full-night polysomnography at the Sleep Division, Peking University People's Hospital, of which 10 patients were combined with obstructive sleep apnea hypopnea syndrome (OSAHS). The median groaning index of patients was 4.8 (1.8, 13.0) events/h. Nasal resistance and cone-beam CT were conducted on the patients, and measurements were performed on the craniofacial structures, upper airway, and surrounding soft tissues, compared with non-snoring normal occlusion individuals' references published by the same research team (144 college students recruited at Peking University and 100 non-snoring young adults with normal occlusion recruited at six universities in Beijing). Results: The total nasal resistance of patients with catathrenia was (0.26±0.08) Pa·cm^-3·s^-1. The patients had overall well-developed mandibular hard tissues. However, the patients were found with increased FH/BaN (steep anterior cranial base plane), increased MP/FH (forward rotation of the mandible); increased U1/NA and L1/MP (proclined upper and lower incisors). The sagittal diameter of the velopharynx [(19.2±4.5) mm] was significantly larger than the normal reference (t=8.44, P<0.001), while the sagittal diameter at the hypopharynx [(17.4±6.4) mm] was statistically smaller than the normal reference (t=-2.79, P=0.006). Catarhrenia patients combined with OSAHS presented longer soft palate, tongue, and lower hyoid bone than those with primary catathrenia. Conclusions: In patients with catathrenia, the overall craniofacial characteristics are well-developed skeletal structures, lower nasal resistance, proclined upper and lower incisors, wide upper sagittal development of the upper airway and narrow hypopharynx. Groaning sounds might be related to the narrowing of the hypopharynx during sleep.