Role of dynamic sleep MRI in obstructive sleep apnea syndrome

Analysis of the cause of retrolingual obstruction in patients with moderate-severe obstructive sleep apnea

PURPOSE

To evaluate the percentage of obstructive sleep apnea (OSA) patients with retrolingual obstruction in all moderate-severe OSA patients and the proportions of different causes in all moderate-severe OSA patients with retrolingual obstruction and to discuss the accuracy of the Friedman tongue position (FTP) and retrolingual cross-sectional area (RCSA) in assessing the retrolingual obstruction.

METHODS

Two hundred and twenty moderate-severe OSA patients were enrolled. After retrolingual obstruction was diagnosed, the percentage of OSA patients with retrolingual obstruction in all moderate-severe OSA patients was calculated. After that, the different causes of retrolingual obstruction were diagnosed based on different diagnostic criteria, and the proportions of different causes in all moderate-severe OSA patients with retrolingual obstruction were calculated. Finally, the correlations between FTP, RCSA, and apnea-hypopnea index after nasopharyngeal tube insertion (NPT-AHI) were analyzed, and the proportions of different causes of retrolingual obstruction based on different FTP and RCSA were observed.

RESULTS

There were 128 patients with retrolingual obstruction, accounting for 58.2% of all moderate-severe OSA patients. In 128 patients with retrolingual obstruction, the proportions of glossoptosis (48.4%), palatal tonsil hypertrophy (28.1%), and lingual hypertrophy (8.6%) were relatively high. Both FTP and RCSA did not correlate with NPT-AHI. The proportion of lingual hypertrophy increased gradually with the increase of FTP and the proportions of glossoptosis in all FTP classifications were high. The patients with RCSA > 180 mm2 were mainly affected by glossoptosis and palatal tonsil hypertrophy, while patients with RCSA ≤ 180 mm2 were mainly affected by lingual hypertrophy.

CONCLUSION

The percentage of patients with retrolingual obstruction in all moderate-severe OSA patients is relatively high, mainly glossoptosis, palatal tonsil hypertrophy, and lingual hypertrophy. FTP classification and RCSA can only reflect the retrolingual anatomical stenosis, but cannot fully reflect the retrolingual functional stenosis, especially the presence of glossoptosis.

Association between nasal airway minimal cross-sectional areas and obstructive sleep apnoea

BACKGROUND/OBJECTIVES

Patients with obstructive sleep apnoea (OSA) frequently present with some form of upper airway anatomical impairment. Considerable research has been conducted on the role of the structures of the jaw and pharynx in the pathogenesis of OSA; however, the significance of the nose is somewhat unclear. Computed tomography is a widely used imaging modality for assessing the nasal cavity and paranasal sinuses, but only a small amount of the acquired data is used. Our aim was to ascertain whether the size of the cross-sectional areas of the nasal airway, measured from cone beam computed tomography (CBCT) images, is associated with OSA severity.

MATERIALS/METHODS

A total of 58 patients with OSA, without any major paranasal sinus inflammatory pathology, were included in this register-based study. Patients had previously undergone ambulatory polysomnography and CBCT. The cross-sectional areas of the nasal cavity were measured in CBCT coronal sections. Statistical analyses were performed to determine any correlation between the cross-sectional area measurements and apnoea-hypopnoea index (AHI) or any significant difference in cross-sectional areas between AHI severity groups.

RESULTS

No correlation was found between AHI and the smallest, total, or sum of the anterior cross-sectional areas of the nasal airway. Furthermore, there was no statistically significant difference in the cross-sectional areas between patients with the highest and lowest AHI.

CONCLUSIONS/IMPLICATIONS

The small cross-sectional area of the anterior nasal cavity in patients without any major nasal pathology does not appear to be associated with OSA severity.

Transverse Maxillary Deficiency Predicts Increased Upper Airway Collapsibility during Drug-Induced Sleep Endoscopy

OBJECTIVE

To examine the relationship between craniofacial skeletal anatomy and objective measures of pharyngeal collapse obtained during drug-induced sleep endoscopy. We hypothesized that transverse maxillary deficiency and an increased pharyngeal length will be associated with higher levels of pharyngeal collapsibility.

STUDY DESIGN

Cross-sectional analysis in a prospective cohort.

SETTING

University Hospital.

METHODS

A cross-sectional analysis was conducted in a cohort of consecutive patients from the positive airway pressure (PAP) alternatives clinic who underwent computed tomography (CT) analysis and drug-induced sleep endoscopy for characterization of upper airway collapsibility. PAP titration was used to determine pharyngeal critical pressure (PCRIT ) and pharyngeal opening pressure (PhOP). CT metrics included: Transverse maxillary dimensions (interpremolar and intermolar distances) and pharyngeal length (posterior nasal spine to hyoid distance).

RESULTS

The cohort (n = 103) of severe obstructive sleep apnea (Apnea and Hipopnea Index 32.1 ± 21.3 events/h) was predominantly male (71.8%), Caucasian (81.6%), middle-aged (54.4 ± 14.3 years), and obese (body mass index [BMI] = 30.0 ± 4.9 kg/m2 ). Reduced transverse maxillary dimensions were associated with higher PCRIT (intermolar distance: β [95% confidence interval, CI] = -.25 [-0.14, -0.36] cmH2 O/mm; p = .03) and PhOP (Interpremolar distance: β = -.25 [-0.14, -0.36] cmH2 O/mm; p = .02). Longer pharyngeal length was also associated with higher PCRIT (β = .11 [0.08, 0.14] cmH2 O/mm, p = .04) and PhOP (β [95% CI] = .06 [0.03, 0.09] cmH2 O/mm, p = .04). These associations persisted after adjustments for sex, age, height, and BMI.

CONCLUSION

Our results further the concept that skeletal restriction in the transverse dimension and hyoid descent are associated with elevations in pharyngeal collapsibility during sleep, suggesting a role of transverse deficiency in the pathogenesis of airway obstruction.

Down Syndrome children with obstructive sleep apnea

INTRODUCTION

Obstructive sleep apnea syndrome (OSAS) is a complex disorder with significant clinical consequences for people with Down Syndrome (DS). OSAS is frequently seen in individuals with DS and, when present, tends to be more severe than in individuals without this syndrome.

EVIDENCE ACQUISITION

The analysis was carried out on PubMed, Google Scholar and Cochrane library databases. The literature review identified nine studies suitable for our evaluations according to the established inclusion criteria.

EVIDENCE SYNTHESIS

The results of the study suggest that OSAS may be a common comorbidity in adolescents with DS; according to literature evidences a widespread screening and treatment in children with DS is undoubtedly useful. There is also evidence about an association between sleep disturbance and functional activities of daily living in children with DS.

CONCLUSIONS

The studies reviewed confirm that OSAS appears to occur at higher rates and greater severity in the population of children with DS. However, at present, there are no reliable clinical predictors of OSAS for this population of children.

Hyoid bone position as an indicator of severe obstructive sleep apnea

BACKGROUND

The objective of this study was to evaluate the relationship between hyoid bone position and severity of obstructive sleep apnea (OSA), and to investigate its value as a complementary diagnostic method.

METHODS

A total of 133 patients who were diagnosed as OSA with an apnea-hypopnea index ≥ 5 were included. Clinical examination, level I polysomnography (PSG) and lateral cephalographic analysis were done. Comprehensive PSG characteristics were compared according to hyoid bone position and the predictive power of the distance between the mandible and hyoid was assessed.

RESULTS

The distance between the hyoid bone and mandibular plane was significantly longer in the severe OSA group (p = 0.013). The distance from hyoid bone to third vertebrae (C3) and hyoid bone to mentum were also longer in the severe OSA group but the difference did not reach statistical significance. The distance between hyoid bone and mandibular plane was effective in predicting severe OSA, with a cut-off value of 19.45 mm (AUC = 0.623, p = 0.040). When grouped according to a distance cut-off value of 19.45 mm, those with a longer distance between the hyoid bone and mandibular plane showed more respiratory disturbance, lower oxygen saturation levels, less deep slow wave sleep, and more fragmented sleep with arousals.

CONCLUSIONS

The distance between the hyoid bone and mandibular plane derived from cephalometric analysis can be a valuable diagnostic parameter that can be easily applied in differentiating severe OSA patients.

Dynamic sleep MRI in obstructive sleep apnea: a systematic review and meta-analysis

PURPOSE

The objective of this study is to systematically review the international literature for dynamic sleep magnetic resonance imaging (MRI) as a diagnostic tool in obstructive sleep apnea (OSA), to perform meta-analysis on the quantitative data from the review, and to discuss its implications in future research and potential clinical applications.

STUDY DESIGN

A comprehensive review of the literature was performed, followed by a detailed analysis of the relevant data that has been published on the topic.

METHODS

Clinical key, Uptodate, Ovid, Ebscohost, Pubmed/MEDLINE, Scopus, Dynamed, Web of Science and The Cochrane Library were systematically searched. Once the search was completed, dynamic sleep MRI data were analyzed.

RESULTS

Nineteen articles reported on 410 OSA patients and 79 controls that underwent dynamic sleep MRI and were included in this review. For meta-analysis of dynamic sleep MRI data, eight articles presented relevant data on 160 OSA patients. Obstruction was reported as follows: retropalatal (RP) 98%, retroglossal (RG) 41% and hypopharyngeal (HP) in 5%. Lateral pharyngeal wall (LPW) collapse was found in 35/73 (48%) patients. The combinations of RP + RG were observed in 24% and RP + RG + LPW in 16%. If sedation was used, 98% of study participants fell asleep compared to 66% of unsedated participants.

CONCLUSIONS

Dynamic sleep MRI has demonstrated that nearly all patients have retropalatal obstruction, retroglossal obstruction is common and hypopharyngeal obstruction is rare. Nearly all patients (98%) who are sedated are able to fall asleep during the MRI. There is significant heterogeneity in the literature and standardization is needed.