Face and neck dimensions could predict who is at increased risk of obstructive sleep apnoea, according to a new study.

Bahn Agha, an orthodontist and clinical postgraduate researcher at Queen Mary University of London, conducted a systematic review and meta-analysis on the relationship between facial and neck dimensions and the presence of obstructive sleep apnoea.

The review found that adults with obstructive sleep apnoea-hypopnoea syndrome (OSAHS) tended to share some distinct features, such as significantly increased neck circumference.

‘The key finding of my systematic review [was that] surface facial morphology could have a potential role in the identification of OSA, particularly the morphology of the mandible,’ said Dr Agha.

More research

While researchers have attempted to predict the presence of OSAHS through questionnaires and facial measurements in the past, Dr Agha felt there was no previously published systematic reviews of surface facial assessment studies in individuals with OSAHS. She also sought to identify study limitations and explore where more research is needed.

For the review, Dr Agha searched medical research databases for studies that used imaging modalities to make surface craniofacial assessments in adults with OSAHS. The review identified eight relevant case-control studies, six of which were judged to be of moderate quality while two provided only low-level evidence.

The results of five studies with 906 participants indicated that adults with OSA had increased weighted mean differences in neck circumference of 1.26mm (p = 0.0001). However, there was extensive heterogeneity among the studies, which Dr Agha said included ill-defined samples, failure to confirm the absence of OSAHS in controls, lack of evaluation of head and neck posture during imaging acquisition, and wide variability in the methods used, such as imaging acquisition.

Two studies provided parameters on mandible length, lower facial height, mandible width, and anterior mandible height. Overall, pooled results found larger parameters in individuals with OSAHS than in controls.

Multifactorial

Dr Agha noted that sleep apnoea is a multifactorial condition that is affected, among other things, by age, ethnicity, gender, alcohol and medication use, and head posture.

‘Neck circumference alone could not predict OSA, as sleep apnoea could affect subjects with normal weight and neck circumference,’ she said. ‘Therefore, combining the craniofacial morphology with other contributing factors, such as hypertension, obesity, male gender, extended head posture, and aging, could improve the prediction of OSA.’

An extended head posture or forward head posture refers to the anterior positioning of the cervical spine in which the neck appears to be extending forward.

Dr Agha believes general dentists could help predict OSA by taking a patient’s history of sleep-related respiratory problems, administering subjective sleep apnoea questionnaires, and using anthropometric measurements, such as neck circumference and body mass index. Identifying a specific facial morphology will help dentists to refer suspected OSA patients to respiratory consultants, which will improve patient care and decrease the economic impact of OSA, she noted.