Does tongue size differ between patients with and without sleep-disordered breathing?

Respiratory internal kinematics of the tongue base and soft palate in obese minipigs with obstructive sleep apnea

It is largely unknown how the tongue base and soft palate deform to alter the configuration of the oropharyngeal airway during respiration. This study is to address this important gap. After live sleep monitoring of 5 Yucatan and 2 Panepinto minipigs to verify obstructive sleep apnea (OSA), 8 and 4 ultrasonic crystals were implanted into the tongue base and soft palate to circumscribe a cubic and square region, respectively. The 3D and 2D dimensional changes of the circumscribed regions were measured simultaneously with electromyographic activity (EMG) of the oropharyngeal muscles during spontaneous respiration under sedated sleep. The results indicated that both obese Yucatan and Panepinto minipigs presented spontaneous OSA, but not in 3 non-obese Yucatan minipigs. During inspiration, the tongue base showed elongation in both dorsal and ventral regions but thinning and thickening in the anterior and posterior regions respectively. The widths showed opposite directions, widening in the dorsal but narrowing in the ventral regions. The soft palate expanded in both length and width. Compared to normal controls, obese/OSA ones showed similar directions of dimensional changes, but the magnitude of change was two times larger in the tongue base and soft palate, and obese/OSA Panepinto minipigs presented 10 times larger changes in all dimensions of both the tongue base and the soft palate. The opposite direction of the respiratory spatial relationship between these two structures was seen in obese/OSA as compared to normal minipigs.

Do dental parameters predict severity of obstructive sleep apnea and mandibular advancement device therapy outcomes? A pilot study

BACKGROUND

Mandibular Advancement Devices (MAD's) are oral appliances commonly used in treatment of Obstructive Sleep Apnea (OSA). OSA severity and certain other factors, such as BMI and neck circumference, correlate with MAD therapy success. So far, the predictive value of dental parameters, such as dental profile, molar-classification, overjet, overbite, maximal retrusion, maximal protrusion and protrusive range, has not been fully investigated.

OBJECTIVES

We aimed to investigate whether dental parameters influence OSA severity and MAD therapy outcome and could therefore be helpful in phenotyping OSA patients. Furthermore, we studied the predictive power of dental parameters for OSA severity and successful MAD therapy. We hypothesise that specific dental parameters correlate with more severe OSA and with more successful MAD treatment.

METHODS

We performed a cohort study, including OSA patients diagnosed by polysomnography (PSG). Dental parameters were collected. Objective treatment outcome was collected by performing a PSG with MAD after three months of therapy. Differences between OSA severity groups and MAD treatment outcomes were analysed and dental parameters were correlated between groups.

RESULTS

The relation between dental parameters and OSA severity was analysed in 143 patients, fifty patients had a PSG with MAD in situ after a 3-month therapy. The median baseline Apnea Hypopnea Index (AHI) significantly reduced from 17.6 (8.7-29.3) to 11.1 (5.5-17.5). Overbite and maximal retrusion differed significantly between mild, moderate and severe OSA. Other dental parameters did not differ significantly between the groups, nor correlated with OSA severity or MAD treatment outcome.

CONCLUSION

In this study, no correlation between dental parameters and OSA severity or MAD treatment outcomes was found. Therefore, screening patients for OSA and MAD treatment outcome based on dental parameters is currently not possible.

Evaluation of volume change in oral cavity proper before and after mandibular advancement

OBJECTIVES

To evaluate the tongue and oral cavity proper volume in pre- and post-bilateral sagittal split osteotomy (BSSO) patients, and to establish whether there was a correlation between them.

MATERIALS AND METHODS

A retrospective study that evaluated 12 patients' pre- and post-surgical computed tomography records satisfying the inclusion criteria. Borders were defined for measurement of tongue and oral cavity proper volume. The volume assessment was carried out using 3D slice software.

RESULTS

The mean difference of tongue volume was 5.7 ± 1.7 cm3, which showed high statistical significance. The mean difference of oral cavity proper volume (OCVP) was 6.9 ± 3.4 cm3 and indicated high statistical significance. A very strong positive correlation existed between pre- and post-surgical tongue volume. Positive correlation was also evident between pre and post - surgical OCVP. Medium positive correlation was noted when the difference between pre- and post-surgical tongue and OCVP were assessed.

CONCLUSIONS

There was a significant change in volume of tongue and oral cavity proper after BSSO advancement surgery. The space around the tongue, position of tongue, and maxillary and mandibular relationship influence the volume of tongue and oral cavity proper.

Real-Time, Intraoperative, Ultrasound-Assisted Transoral Robotic Surgery for Obstructive Sleep Apnea

OBJECTIVES/HYPOTHESIS

To investigate the lingual artery (LA) position in the tongue base through intraoperative ultrasound (IOU) imaging during transoral robotic surgery (TORS) and evaluate bleeding complications with or without the assistance of IOU.

STUDY DESIGN

Cohort study with historical control.

METHODS

Patients with obstructive sleep apnea (OSA) who underwent TORS for tongue base resection were recruited since 2016. During surgery, ultrasound imaging was employed to identify anatomic parameters of the LA in the tongue base, including distance to the midline and arterial depth and diameter.

RESULTS

Ninety-three OSA patients (82 men, 88.2%) were analyzed. Mean age was 42.2 ± 10.0 years and body mass index was 29.2 ± 4.5 kg/m² . Average apnea-hypopnea index (AHI) was 58.1 ± 21.4 events/hour. Overall, 70 patients who underwent TORS with IOU had a shorter operation time (191.7 ± 3.8 vs. 220.1 ± 6.6 minutes), lower total blood loss (11.3 ± 10.8 vs. 19.6 ± 26.7 mL), and higher tongue base reduction volume (7.1 ± 2.5 vs. 3.9 ± 1.6 mL) than 23 patients who underwent TORS without IOU. Significant predictors of arterial depth included higher AHI level during the rapid eye movement sleep (P = .038), larger tonsil size (P = .034), and more elevated Friedman tongue position (P = .012). Postoperative complications associated with LA injury were not found in patients subjected to IOU.

CONCLUSIONS

With the assistance of IOU, surgeons can confidently determine LA position. The use of IOU can maximize efficiency and minimize catastrophic bleeding complications when OSA patients undergo TORS for tongue base resection.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E1383-E1390, 2021.

A Screening Algorithm for Obstructive Sleep Apnea in Pregnancy

Rationale: Obstructive sleep apnea (OSA) is common in pregnancy and associated with maternal and fetal complications. Early detection of OSA may have important implications for maternal-fetal well-being. A screening tool combining several methods of assessment may better predict OSA among pregnant women compared with tools that rely solely on self-reported information.Objectives: To develop a screening tool combining subjective and objective measures to predict OSA in pregnant women.Methods: This study is a secondary analysis using data collected from a completed cohort of pregnant women (n = 121 during the first and n = 87 during the third trimester). Participants underwent full polysomnography and completed the Multivariable Apnea Prediction Questionnaire. The Obstructive Sleep Apnea/Hypopnea Syndrome Score and Facco apnea predictive model were obtained. Logistic regression analysis and area under the curve (AUC) were used to identify models predicting OSA risk.Results: Participants' mean age was 27.4 ± 7.0 years. The prevalence of OSA during the first and third trimester was 10.7% and 24.1%, respectively. The final model predicting OSA risk consisted of body mass index, age, and presence of tongue enlargement. During the first trimester, the AUC was 0.86 (95% confidence interval [CI], 0.76-0.96). During the third trimester, the AUC was 0.87 (95% CI, 0.77-0.96). When the first-trimester data were used to predict third-trimester OSA risk, the AUC was 0.87 (95% CI, 0.77-0.97). This model had high sensitivity and specificity when used during both trimesters. The negative posttest probabilities (probability of OSA given a negative test result) ranged from 0.03 to 0.07.Conclusions: A new model consisting of body mass index, age, and presence of tongue enlargement provided accurate screening of OSA in pregnant women, particularly African-Americans. This tool can be easily and rapidly administered in busy clinical practices without depending on patients' awareness of experiencing apnea symptoms.

Evaluation of tongue volume and oral cavity capacity using cone-beam computed tomography

The aims of this study were to reveal the usefulness of a newly developed method for measuring tongue volume (TV) and oral cavity capacity (OCC) and to assess the relationship between them. The tongue was coated with a contrast agent, and the TV and OCC were determined using cone-beam computed tomography (CBCT). We enrolled 20 adults who were scheduled to undergo CBCT to evaluate the relationship of the third molar roots to the alveolar nerve before molar extraction. Each participant’s tongue was coated with a contrast agent, and CBCT of the tongue and oral cavity was performed. Using computer software, we evaluated reconstructed 3D images of the TV, oral cavity proper volume (OCPV), and OCC. The mean TV was 47.07 ± 7.08 cm³. The mean OCPV and OCC were 4.40 ± 2.78 cm³ and 51.47 ± 6.46 cm³, respectively. There was a significant correlation between TV and OCC (r = 0.920; p < 0.01) but not between TV and OCPV. The mean TV/OCC ratio was 91 ± 5%. The proposed method produced CBCT images that enabled effective measurement of TV and OCC. This simple method of measuring TV and OCC will be useful in the diagnosis on the tongues with abnormal size.

Previsional space during direct laryngoscopy: Implication in the difficult laryngoscopy

The laryngoscope should displace oral soft tissues forward out of the operator's vision. Therefore, the space in front of the view may be critical for determining the laryngoscopic view. The aim was to investigate the difference in the previsional space during difficult versus easy laryngoscopy (EL).Under general anesthesia, digital photographs of the lateral view of the head and neck were taken in the horizontal sniffing position, after head extension, and during laryngoscopy with a defined force (50 N). Three points (thyroid notch (T), maxillary incisor (I), and mandibular mentum (M)) were marked on the photograph. The previsional space was defined as the TIM triangle. We compared these areas and other variables of the TIM triangle between male patients with difficult laryngoscopy (DL: Cormack-Lehane III-IV, n = 12) versus those of age- and body mass index-matched male patients with EL (Cormack-Lehane I-II, n = 12).When the head was extended, the areas TIM triangle in DL were significantly smaller than in EL. During laryngoscopy, all values of the TIM triangle in DL, including the TIM area (16.4 ± 3.7 vs 22.6 ± 2.8 cm, P < .01), were significantly smaller than the values in EL.The previsional space was smaller in patients with DL than in those with EL. The TIM triangle could suggest new way to explain the mechanism underlying DL.

Correlation between change of tongue area and skeletal stability after correction of mandibular prognathism

The purpose of this study was to investigate the correlation between postoperative stability and a change in tongue area after treatment of mandibular prognathism. Twenty-six patients, who were treated for mandibular prognathism using intraoral vertical ramus osteotomy, were evaluated cephalometrically. A set of three standardized lateral cephalograms were obtained from each participant preoperatively (T1), immediately postoperatively (T2), and after 2 years postoperatively (T3). Student t test and Pearson correlation coefficient were used for statistical analysis. Immediately after the surgery (T12), the setback of the menton (Me) was 12.9 mm (p<0.001) and the tongue area had significantly increased to 105.8 mm² (p=0.047). At a 2-year follow-up to examine postsurgical stability (T23), the Me exhibited a forward movement of 0.6 mm (p=0.363) and the tongue area had significantly decreased to 124.3 mm² (p=0.004). Pearson correlation coefficient test revealed no statistical significance between postoperative stability and change in tongue area. The tongue area significantly increased during the T12 period and decreased during the T23 period. There is no significant correlation between postoperative skeletal relapse and a change in tongue area.

Scalloped tongue is associated with nocturnal intermittent hypoxia among community-dwelling Japanese: the Toon Health Study

Scalloped tongue is considered as a possible clinical finding of obstructive sleep apnoea (OSA). There are few evidence of the association between scalloped tongue and OSA. To examine the association between scalloped tongue and nocturnal intermittent hypoxia (NIH), a surrogate marker of OSA, among a general Japanese population. Study participants were 398 men and 732 women aged 30-79 years who participated in the Toon Health Study from 2011 to 2014. Scalloped tongue was classified into three categories: none, mild and moderate-to-severe. Moderate-to-severe NIH was defined as the 3% oxygen desaturation index of ≥15 events/h during sleep for one night with pulse oximetry. The multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for moderate-to-severe NIH were calculated according to scalloped tongue categories using a logistic regression model. There were 69 (6·1%) moderate-to-severe NIH cases in this population. The multivariable-adjusted ORs (95% CIs) of moderate-to-severe NIH were 1·59 (0·85-2·95) for mild and 2·39 (1·10-5·17) for the moderate-to-severe scalloped tongue group compared with the group without scalloped tongues. When stratified by overweight status (BMI <25 or ≥25 kg m^-2 ), the respective ORs (95% CIs) were 2·83 (1·06-7·55) and 4·74 (1·28-17·49) among overweight individuals, and 0·94 (0·40-2·70) and 1·52 (0·57-4·05) among non-overweight individuals. Scalloped tongue was associated with higher prevalence of moderate-to-severe NIH among the general Japanese population and this association was more evident in overweight individuals.

State of the art transoral robotic surgery for obstructive sleep apnea-hypopnea syndrome

Objective

To review the existing literature on the role of transoral robotic surgery (TORS) for tongue base reduction in the management of adult obstructive sleep apnea-hypopnea syndrome (OSAHS).

Methods

We searched PubMed, MEDLINE, and Scopus databases from the first literature report of this surgical technique to July 30, 2015 for studies investigating the use of TORS for tongue base reduction in treating adult OSAHS. Our primary outcome measures were Apnea– Hypopnea Index (AHI), lowest oxygen saturation (LSAT), Epworth Sleepiness Score (ESS), and the rates of surgical cure (AHI<5) and success (50% reduction in AHI accompanied by a postoperative AHI<20). Our secondary outcome measures were the volume of tissue resected and correlation to AHI, polysomnographic parameters, subjective outcomes, and body mass index. Complications of surgery were also analyzed.

Results

Thirteen articles were critically evaluated for this research. However, only four case series qualified for statistical analysis of postoperative polysomnographic outcomes and six case series for analysis of postoperative complications. They were case series with a total of 451 adult patients. Pooled analysis revealed statistically significant improvements in AHI, LSAT, and ESS after surgery by 26.83/hour, 5.28% and −8.03, respectively. The average rates of surgical cure and success were 23.8% and 66.7%, respectively. No study reported any deaths or complications related to the use of robotic equipment. The major complication rate was 6.9%, and the minor complication rate was 30.0%. Major complications included major bleeding (2.9%), severe odynophagia with dehydration (3.3%), and oropharyngeal stenosis (0.7%). Minor complications included transient bleeding (0.5%), transient dysphagia (3.8%), and dysgeusia (6.6%).

Conclusion

TORS for tongue base reduction, as a component of multilevel surgery, is an effective treatment option for OSAHS with an acceptable morbidity. This conclusion is based on the analysis of the results of multiple case series. Future studies should entail prospective randomized controlled trials with larger sample size for longer follow-up period.

Tongue volume in adults with skeletal Class III dentofacial deformities

Background

The size of the tongue is implicated as an essential etiological factor in the development of malocclusions. The aim of our study was to assess tongue size in skeletal Class III (SCIII) patients in comparison to adults with normal occlusion, using three-dimensional (3D) ultrasound.

Methods

The SCIII group consisted of 54 subjects; 34 females and 20 males and the control group contained 36 subjects, 18 from each gender with Class I relationship. 3D ultrasound images of the tongues were acquired, and then the tongues’ volumes were assessed.

Results

The males in both the SCIII and control groups had significantly larger tongue volumes than the female subjects (mean SCIII 100.8 ± 6.3 and control 92.4 ± 9.8 cm³ in males vs. SCIII 77.4 ± 10.2 and control 67.2 ± 5.6 cm³ in females). The highly significantly larger tongue volumes were in SCIII patients of both genders (p were less than 0.01 for female and 0.03 for male). The tongue volumes within the whole SCIII group were significantly larger with more negative Wits values.

Conclusion

The tongue volumes are significantly bigger in SCIII subjects than normal. Larger tongues correlate with more severe SCIII. The clinical importance of this data is that limited mandibular setback planning is necessary to prevent narrowing of respiratory airways.

The Effect of Glossectomy for Obstructive Sleep Apnea

Objective

Determine the effect of glossectomy as part of multilevel sleep surgery on sleep-related outcomes in patients with obstructive sleep apnea.

Data Sources

PubMED, Scopus.

Review Methods

Two independent researchers conducted the review using PubMed-NCBI and Scopus literature databases. Studies on glossectomy for obstructive sleep apnea that reported pre- and postoperative apnea-hypopnea index (AHI) score with 10 or more patients were included.

Results

A total of 18 articles with 522 patients treated with 3 glossectomy techniques (midline glossectomy, lingualplasty, and submucosal minimally invasive lingual excision) met inclusion criteria. Pooled analyses (baseline vs post surgery) showed a significant improvement in AHI (48.1 ± 22.01 to 19.05 ± 15.46, P < .0001), Epworth Sleepiness Scale (ESS; 11.41 ± 4.38 to 5.66 ± 3.29, P < .0001), snoring visual analog scale (VAS; 9.08 ± 1.21 to 3.14 ± 2.41, P < .0001), and Lowest O2 saturation (76.67 ± 10.58 to 84.09 ± 7.90, P < .0001). Surgical success rate was 59.6% (95% CI, 53.0%-65.9%) and surgical cure was achieved in 22.5% (95% CI, 11.26%-36.26%) of cases. Acute complications occurred in 16.4% (79/481) of reported patients. Glossectomy was used as a standalone therapy in 24 patients. In this limited cohort, significant reductions in AHI (41.84 ± 32.05 to 25.02 ± 20.43, P = .0354) and ESS (12.35 ± 5.05 to 6.99 ± 3.84, P < .0001) were likewise observed.

Conclusion

Glossectomy significantly improves sleep outcomes as part of multilevel surgery in adult patients with OSA. Currently, there is insufficient evidence to analyze the role of glossectomy as a standalone procedure for the treatment of sleep apnea, although the evidence suggests positive outcomes in select patients.

Craniofacial characteristics related to daytime sleepiness screened by the paediatric daytime sleepiness scale

The present cross-sectional study aimed to assess daytime sleepiness in Chinese adolescents using the Paediatric Daytime Sleepiness Scale (PDSS) and to identify associations between PDSS answers and craniofacial characteristics. A group of 265 Chinese adolescents aged 11-17 years self-completed the PDSS, and their extra- and intra-oral craniofacial characteristics were recorded. Among the participants, 59.7% (157) experienced one or more daytime sleepiness events. No significant associations were found between total PDSS scores and the craniofacial parameters, but when PDSS answers were assessed at the item level, several craniofacial characteristics were found to be positively associated with daytime sleepiness, such as hypertrophic tonsils (P = 0.05), a relatively large tongue (P < 0.01), a bilateral Class II molar relationship (P < 0.05) and increased overjet (P < 0.05). A short lower face (P < 0.01) and a convex profile (P < 0.01) were found to be negatively associated with daytime sleepiness. Daytime sleepiness is commonly reported among Chinese adolescents seeking orthodontic treatment and there are potential associations between the condition and craniofacial characteristics. An assessment of daytime sleepiness is recommended to orthodontists in young patients presenting with hypertrophic tonsils, relative large tongues and Class II tendency malocclusions, and appropriate medical referrals should also be considered.

Submucosal Lingualplasty for Adult Obstructive Sleep Apnea

Objective

To measure quality-of-life outcomes, polysomnographic outcomes, and adverse effects for a new technique of tongue reduction in obstructive sleep apnea.

Study Design

Case series.

Setting

Tertiary hospital.

Subjects and Methods

Consecutively treated adult patients (N = 27) with obstructive sleep apnea having submucosal lingualplasty in 2007 were studied. All had concurrent or previous uvulopalatoplasty ± palatal advancement. Full polysomnography preoperatively and 3.7 ± 0.4 months postoperatively, scored using the American Academy of Sleep Medicine 2007 criteria, was recorded. Snoring severity score, Epworth Sleepiness Scale, and complication data were collected at a 2.61 ± 0.08-year follow-up via questionnaire.

Results

Mean snoring severity score fell from 7.1 ± 0.4 to 2.3 ± 0.6 ( P < .05). Epworth Sleepiness Scale score fell from 8.3 ± 1.1 to 5.8 ± 1.0 ( P < .05). The apnea-hypopnea index (AHI) fell from 44.0 ± 4.3 to 12.5 ± 2.3 ( P < .05). Success, defined as achieving an AHI <15 postoperatively, was observed in 74% (20/27), with each of these patients achieving a reduction in AHI >50%. Lowest oxygen saturation improved from 84 ± 1 to 88 ± 1 ( P < .05). Pain was mild to moderate. Short-term postoperative complications included bleeding (3.7%) and infection (14.8%). Some minor long-term (6 months) alteration in tongue function was reported with regard to speech (47%), swallow (33%), and taste (33%).

Conclusion

Submucosal lingualplasty with concurrent palatal surgery is a promising treatment option in adult patients with obstructive sleep apnea with macroglossia.

Tonsil volume, tonsil grade and obstructive sleep apnea: is there any meaningful correlation?

OBJECTIVES

The aims of this study were to evaluate the correlation between oropharyngeal examination and objective palatine tonsil volume in snoring adults and verify the influence of the oropharyngeal anatomy, body mass index, age, and severity of obstructive sleep apnea on actual tonsil volume. In addition, we aimed to assess the influence of tonsil size on obstructive sleep apnea in adults.

INTRODUCTION

Pharyngeal wall geometry is often altered in adults who have obstructive sleep apnea, and this might influence the findings of the oropharyngeal examination that, in turn, are the key factors when considering surgical management for this condition. Furthermore, the correlation between the actual tonsil volume and the severity of obstructive sleep apnea in adults is currently unknown.

METHODS

We prospectively studied 130 patients with obstructive sleep apnea or primary snoring who underwent pharyngeal surgery with intraoperative measurement of tonsil volume. We compared tonsil volume with preoperative polysomnography, oropharyngeal examination, and anthropometric data.

RESULTS

We found a significant correlation between actual tonsil volume and subjective tonsil grade. We also found a significant correlation between tonsil volume and the apnea-hypopnea index. Using a multivariate linear regression model, tonsil volume was found to be significantly correlated with age, body mass index, and oropharyngeal examination, but not with polysomnography. Clinically, only the rare tonsil grade IV was indicative of more severe obstructive sleep apnea.

CONCLUSIONS

There is a strong correlation between clinical tonsil grade and objective tonsil volume in snoring adults, and this correlation exists regardless of the presence or severity of obstructive sleep apnea. Pharyngeal tissue volume likely reflects the body mass index rather than obstructive sleep apnea severity.

Classification of sleep apnea through sub-band energy of abdominal effort signal using Wavelets + Neural Networks

Detection and classification of sleep apnea syndrome (SAS) is a critical problem. In this study an efficient method for classification sleep apnea through sub-band energy of abdominal effort using a particularly designed hybrid classifier as Wavelets + Neural Network is proposed. The Abdominal respiration signals were separated into spectral sub-band energy components with multi-resolution Discrete Wavelet Transform (DWT). The energy content of these spectral components was applied to the input of the artificial neural network (ANN). The ANN was configured to give three outputs dedicated to SAS cases; obstructive sleep apnea (OSA), central sleep apnea (CSA) and mixed sleep apnea (MSA). Through the network, satisfactory results that rewarding 85.62% mean accuracy in classifying SAS were obtained.

[Update on upper airway evaluation in obstructive sleep apnea]

During the past two decades, different methods of upper airway evaluation for patients with obstructive sleep apnea (OSA) have been investigated. Although clinical assessment is the basis of any diagnostic workflow in OSA, the Mueller maneuver is apparently of no importance. Imaging techniques have increased our knowledge of the pathophysiology of OSA. Cephalometry is done only if maxillomandibular advancement is planned; dynamic investigations such as computed tomography and magnetic resonance imaging are able to picture the pharyngeal collapse and have the capacity to simulate the effect of interventions on OSA severity. So far, video endoscopy under sedation can only predict the success of oral appliances. Multichannel pressure recordings depict the distribution of obstructive events in the upper or lower pharyngeal segment during the entire night. The impact of sophisticated upper airway evaluation remains limited compared with standard clinical assessment. Further research is needed to develop valuable tools for the diagnostic workup of patients with OSA.

Lingual fat at autopsy

OBJECTIVES/HYPOTHESIS

Obesity as measured by body mass index (BMI) has been shown to correlate with incidence and severity of sleep disordered breathing (SDB), but the actual mechanism underlying this relationship has not been defined. Pharyngeal obstruction from posterior displacement of a large, fat laden tongue is one mechanism that may explain this link. The objective of this study is to characterize the fat content within the tongue and then to determine whether tongue weight and percent of fat correlate with BMI and other metrics of obesity.

STUDY DESIGN

This is a cross-sectional anatomic study performed at autopsy in 121 consecutive medical examiner cases.

METHODS

Tongues were harvested, weighed, and sectioned. A standardized photograph was taken of each tongue in the midsagittal plane. The image was imported into ImageJ (NIH) and then digitally analyzed to estimate fat distribution and percent within the tongue. The measurements were divided into age and sex subsets and then examined for correlation with height, weight, BMI, organ weight, and abdominal subcutaneous fat thickness.

RESULTS

This study includes data from 88 males, 27 females, and 6 children. The average tongue weight for males was 99 g, range 71 to 143 g; for females, 79 g, range 51 to 135 g; and for children, (mean age 4 yr) 38 g, range 15 to 81 g. Tongue weight correlated with BMI (r = 0.6, P < .0001). Percent of fat in the posterior tongue averaged 30 +/- 12% and correlated with BMI (r = 0.5, P < .0001) for both men and women. Percent of fat in the anterior tongue averaged 10 +/- 5% and correlated with BMI for males (P < .001). Anterior tongue fat percent did not correlate with BMI in females.

CONCLUSION

Increase in tongue weight and percentage of fat, and therefore tongue volume, may explain why patients with weight gain have higher rates of SDB. Tongue weight, fat, and volume may also correlate with and explain Mallampati grades.

Physiology of Sleep Disordered Breathing

Obstructive sleep apnea (OSA) results from complex interactions between anatomy and physiology. A structurally small and abnormally collapsible upper airway predisposes to disease, and interacts with normal and pathologic physiologic mechanisms to determine severity of disease. Understanding the pathophysiology provides insight into airway collapse, and may improve treatment and lead to potential new medical and surgical treatments for OSA.

Evaluating the upper airway with standardized magnetic resonance imaging

OBJECTIVES/HYPOTHESIS

Magnetic resonance imaging (MRI) potentially offers various advantages in assessing the upper airway. The aims of the presented study were 1) to evaluate which anatomical parameters of upper airway soft tissue morphology (distances, areas, volumes) could be defined using MRI scans, 2) to examine the stability or variability of these parameters over time and between different investigators, and 3) to develop a standardized protocol for MRI measurements of the upper airway.

STUDY DESIGN

Prospective clinical trial.

METHODS

Twenty-four scans were performed on six healthy subjects over a period of 4 weeks. Various parameters such as tongue dimensions, volumes and spaces, posterior airway spaces, and soft palate dimensions were established, and their variation over time between different investigators and with repeated analysis was assessed.

RESULTS

All the parameters were of high stability and reproducibility. The time of day had no significant influence on the results. An abbreviated method for the evaluation of the tongue volume was developed. Four-millimeter slices with a conventional MRI scan generate pictures of high quality in a maintainable acquisition time.

CONCLUSIONS

We were able to evaluate which anatomical parameters of upper airway could be defined using MRI scans. The variability of these parameters over time and between different investigators was assessed. We developed a standardized protocol for MRI measurements of the upper airway. Standardized protocols are mandatory, and the variability of the measurements must be taken into account if results of different clinical centers must be compared or if changes after therapeutic interventions are to be investigated.

Prediction formulae for sleep-disordered breathing

Prediction formulae for sleep-disordered breathing can be useful for excluding a diagnosis, establishing an a priori probability of having a positive test, and for prioritizing patient testing. In general, prediction models have high sensitivity but low specificity. In a study analyzing the performance of four previously described prediction models, sensitivities ranged from 76% to 96%, specificities ranged from 13% to 54%, while positive predictive values ranged between 69% and 77%. The models were useful in identifying patients with a respiratory disturbance index of > or = 20 so that these patients could undergo alternative diagnostic testing strategies. The Berlin Questionnaire was tested in primary care settings and was able to identify high-risk patients fairly accurately. A regression neural network performed well with a sensitivity of 99%, a specificity of 80%, a positive predictive value of 88%, and a negative predictive value of 98%. In obese snorers, a regression model utilizing daytime arterial O2 saturation and specific respiratory conductance was effective for excluding obstructive sleep apnea (OSA). In congestive heart failure patients, risk factors for central sleep apnea include male gender, atrial fibrillation, age >60 years, and wake time PaCO2 <38 mm Hg. In children, risk factors for sleep apnea include obesity, African-American race, sinus problems, and persistent wheezing. There are also racial anthropomorphic differences in OSA patients, with whites having a tendency towards brachycephaly facial types (reduced anterior-posterior cranial dimension) and African-Americans having a tendency toward leptoproscopic facial types (longer facial height and decreased facial width). Further refinement of prediction formulae will improve diagnostic accuracy.