New insights on the role of the insular cortex and habenula in OSA

A comparison of the outcomes of tonsillectomy and expansion sphincter pharyngoplasty operations in patients with obstructive sleep apnea

OBJECTIVE

To compare the efficacy of tonsillectomy and expansion sphincter pharyngoplasty (ESP) in the surgical treatment of obstructive sleep apnea (OSA).

METHODS

OSA patients with Friedman grade III-IV tonsil hypertrophy diagnosed with polysomnography were separated into two groups according to the surgery performed, as the classic tonsillectomy group (Group 1) and the ESP group (Group 2). The primary endpoint of the study was to determine the Apnea-Hypopnea Index (AHI) value.

RESULTS

Group 1 comprised 24 patients with median preoperative AHI of 19.7 and postoperative AHI of median 11.8 (p = .0001). Group 2 comprised 29 patients with median preoperative AHI of 25.1 and postoperative AHI of median 16.3 (p = .0001). Nine (37.5%) of the 24 patients in Group 1 accepted as cure (79.1%). Eight (27.5%) of the 29 patients in Group 2 accepted as cure (72.4%).

CONCLUSION

There was no superiority of ESP over tonsillectomy in patients with lateral pharyngeal obstruction.

Associations between body mass index, sleep-disordered breathing, brain structure, and behavior in healthy children

Pediatric overweight/obesity can lead to sleep-disordered breathing (SDB), abnormal neurological and cognitive development, and psychiatric problems, but the associations and interactions between these factors have not been fully explored. Therefore, we investigated the associations between body mass index (BMI), SDB, psychiatric and cognitive measures, and brain morphometry in 8484 children 9-11 years old using the Adolescent Brain Cognitive Development dataset. BMI was positively associated with SDB, and both were negatively correlated with cortical thickness in lingual gyrus and lateral orbitofrontal cortex, and cortical volumes in postcentral gyrus, precentral gyrus, precuneus, superior parietal lobule, and insula. Mediation analysis showed that SDB partially mediated the effect of overweight/obesity on these brain regions. Dimensional psychopathology (including aggressive behavior and externalizing problem) and cognitive function were correlated with BMI and SDB. SDB and cortical volumes in precentral gyrus and insula mediated the correlations between BMI and externalizing problem and matrix reasoning ability. Comparisons by sex showed that obesity and SDB had a greater impact on brain measures, cognitive function, and mental health in girls than in boys. These findings suggest that preventing childhood obesity will help decrease SDB symptom burden, abnormal neurological and cognitive development, and psychiatric problems.

The Effects of the Newest Palatopharyngeal Surgery (Barbed Pharyngoplasty) on Voice Quality

OBJECTIVES

This study aimed to examine the effects of barbed pharyngoplasty (BP) on voice quality in patients with Obstructive sleep apnea syndrome (OSAS) and to compare them with the anterior palatoplasty (AP) and expansion sphincter pharyngoplasty (ESP) surgeries.

METHODS

The study included 329 patients who came to the Otorhinolaryngology Clinic of our hospital with symptoms of snoring and sleep apnea between January 2020 and 2022 and were referred to the sleep laboratory for polysomnography (PSG). AP surgery was recommended for those with retropalatal stenosis in the anteroposterior direction, and ESP surgery for those with lateral stenosis. BP was recommended for those with both anteroposterior and lateral retropalatal stenosis. 60 patients who met the study criteria were included in the study. All surgeries were performed under general anesthesia by the same otolaryngologist within 1 month at the latest after sleep endoscopy. Acoustic voice analysis was performed using the Praat voice analysis program preoperatively and postoperatively at 6 months. F0, jitter, shimmer, and NHR (noise-to-harmonic ratio) were compared between groups pre and postoperatively.

RESULTS

F0 %, jitter %, shimmer %, and NHR % changes were highest in BP. Jitter, shimmer, and NHR decreased significantly in the BP group, whereas F0 increased significantly. Although the mean F0 increased in both AP and ESP groups, the greatest change was in the AP group following BP groups. Although the average jitter, shimmer, and NHR decreased in both groups, the greatest change was in the ESP group following BP groups.

CONCLUSION

In patients with OSAS, BP surgery changed F0, jitter, shimmer and NHR more than AP and ESP surgeries, and effected the voice quality more positively.

Functional Connectivity Changes in the Insular Subregions of Patients with Obstructive Sleep Apnea after 6 Months of Continuous Positive Airway Pressure Treatment

This study was aimed at investigating the functional connectivity (FC) changes between the insular subregions and whole brain in patients with obstructive sleep apnea (OSA) after 6 months of continuous positive airway pressure (CPAP) treatment and at exploring the relationship between resting-state FC changes and cognitive impairment in OSA patients. Data from 15 patients with OSA before and after 6 months of CPAP treatment were included in this study. The FC between the insular subregions and whole brain was compared between baseline and after 6 months of CPAP treatment in OSA. After 6 months of treatment, OSA patients had increased FC from the right ventral anterior insula to the bilateral superior frontal gyrus and bilateral middle frontal gyrus and increased FC from the left posterior insula to the left middle temporal gyrus and left inferior temporal gyrus. Hyperconnectivity was found from the right posterior insula to the right middle temporal gyrus, bilateral precuneus, and bilateral posterior cingulate cortex, which mainly involved the default mode network. There are changes in functional connectivity patterns between the insular subregions and whole brain in OSA patients after 6 months of CPAP treatment. These changes provide a better understanding of the neuroimaging mechanisms underlying the improvement in cognitive function and emotional impairment in OSA patients and can be used as potential biomarkers for clinical CPAP treatment.

The Effects of Anterior Palatoplasty and Functional Expansion Sphincter Pharyngoplasty on Voice Quality in Patients with Obstructive Sleep Apnea

OBJECTIVES

We aimed to examine the effects of anterior palatoplasty (AP) and functional expansion sphincter pharyngoplasty (FESP) on voice quality in patients with OSAS and to compare them with each other.

MERHODS

The study included 380 patients who came to the Otorhinolaryngology Clinic of our hospital with symptoms of snoring and sleep apnea between April 2020 and April 2022 and were referred to the sleep laboratory for polysomnography (PSG).Forty patients who met the study criteria and underwent AP and 26 patients who underwent FESP were included in the study. All surgeries were performed under general anesthesia by the same otolaryngologist within 1 month at the latest after sleep endoscopy. Acoustic voice analysis was performed using the Praat voice analysis program preoperatively and postoperatively at 6 months. F0, jitter, shimmer, and NHR (noise-to-harmonic ratio) were compared between the groups pre and postoperatively.

RESULTS

There were 20 females and 20 males in the AP group, 12 females and 14 males in the FESP group, There was no statistically significant difference in sex distribution between the groups (P = 0.952). The difference between the preop and postop F0, jitter, shimmer, and NHR in both the AP and FESP groups was statistically significant (P < 0.01). After AP and FESP surgeries, F0 values ​​increased, jitter, shimmer and NHR values ​​decreased (P < 0.01).F0, jitter, shimmer, and NHR changes were the greatest in the FESP group.(P < 0.01).

CONCLUSION

Positive changes in F0, jitter, shimmer, and NHR were greatest in the FESP group significantly. FESP surgery affects voice quality more than AP surgery in patients with OSAS.

fMRI studies evaluating central respiratory control in humans

A plethora of neural centers in the central nervous system control the fundamental respiratory pattern. This control is ensured by neurons that act as pacemakers, modulating activity through chemical control driven by changes in the O2/CO2 balance. Most of the respiratory neural centers are located in the brainstem, but difficult to localize on magnetic resonance imaging (MRI) due to their small size, lack of visually-detectable borders with neighboring areas, and significant physiological noise hampering detection of its activity with functional MRI (fMRI). Yet, several approaches make it possible to study the normal response to different abnormal stimuli or conditions such as CO2 inhalation, induced hypercapnia, volitional apnea, induced hypoxia etc. This review provides a comprehensive overview of the majority of available studies on central respiratory control in humans.

Aberrant amplitude of low-frequency fluctuations in different frequency bands and changes after one-night positive airway pressure treatment in severe obstructive sleep apnea

Objective

This study was aimed to investigate the characteristics of the amplitude of low-frequency fluctuation (ALFF) at specific frequencies in severe obstructive sleep apnea (OSA) patients. A comparison was made between pre-CPAP treatment and one night after continuous positive airway pressure (CPAP) treatment.

Methods

30 severe OSA patients and 19 healthy controls (HC) were recruited. The ALFF method was used to assess the local features of spontaneous brain activity and calculated at different bands (slow-5 and slow-4). A correlation analysis was performed to evaluate the relationship between the changes of the ALFF and polysomnography data.

Results

Compared with HC, in slow-5 frequency band, OSA patients showed significantly decreased ALFF in the left inferior temporal gyrus, and significantly increased ALFF in the left middle frontal gyrus, left inferior frontal gyrus, triangular part, right superior frontal gyrus, dorsolateral and right middle temporal gyrus. In slow-4 frequency, there was significantly decreased ALFF in the right inferior temporal gyrus, and significantly increased ALFF in the left precuneus, right posterior cingulate gyrus and right median cingulate besides the slow-5 difference band showed. Compared with pre-CPAP, we found that after CPAP treatment, ALFF signals in the left insula in slow-5 and left caudate in slow-4 increased, but the calcarine in slow-4 significantly reduced. Correlation analysis showed that the left angular slow-4 band change was positively correlated with the slow wave sleep change (r = 0.4933, p = 0.0056). The left cerebellum 6 slow-5 band change was positively correlated with the duration of the REM sleep change (r = 0.4563, p = 0.0113), and the left cerebellum 6 slow-4 band change was also positively correlated with the mean blood oxygen change in the REM (r = 0.4591, p = 0.0107) and NREM sleep (r = 0.4492, p = 0.0128).

Conclusion

We found that the use of slow-4 was more specific in OSA studies. These results suggested that the severe OSA patients have frequency-related abnormal spontaneous neural activity, which may contribute to a better understanding of the pathological basis of OSA-related diseases and provide a potential therapeutic target for OSA patients.

Optimal application of soft-palate webbing flap pharyngoplasty combined with nasal surgery for surgical treatment of primary snoring and obstructive sleep apnea

Background

Excessive collapse of the soft palate and lateral pharyngeal wall narrowing are established causes of loud snoring and sleep apnea in subjects with obstructive sleep apnea (OSA). Therefore, delicate surgical techniques are needed to reshape the soft palate and create sufficient tension in the lateral pharyngeal wall. This study aimed to determine the therapeutic outcome and favorable indications of soft-palate webbing flap pharyngoplasty in subjects with OSA and primary snoring.

Methods

A total of 174 subjects who underwent soft-palate webbing flap pharyngoplasty combined with uvulopalatal flap and septoturbinoplasty from August 2015 to February 2020 were included in this study. Medical records, including pre- and postoperative sleep parameters, were retrospectively reviewed. The primary outcome measure was the degree of improvement in AHI after surgery. Other outcomes were differences in surgical response rates, subjective visual analog score (VAS) for snoring, sleep quality, and complications.

Results

Polysomnographic results showed that apnea–hypopnea index (AHI) scores were significantly reduced from 39.6 ± 6.1 to 22.9 ± 3.6 following soft-palate webbing flap pharyngoplasty in 59 subjects, and overall success and response rates of this technique were analyzed with 71%. We found that the successful outcomes were observed in 50% of mild (n = 12) and 56% of moderate (n = 16) subjects with OSA subjects due to lateral pharyngeal wall collapse. The success rate of soft-palate webbing flap pharyngoplasty was relatively higher in subjects with mild and moderate OSA than those with severe OSA. Additionally, the mean VAS snoring scale was 4.7 and subjects’ primary snoring intensity significantly improved to 2.9 after soft-palate webbing flap pharyngoplasty. Subjective symptoms such as daytime sleepiness and sleep quality also showed improvement. Most complications were found to be minimal and improved by 1 month after the operation.

Conclusion

Our data demonstrate that soft-palate webbing flap pharyngoplasty is an effective treatment for OSA and primary snoring and may be a promising technique to reduce lateral pharyngeal wall collapse.

Aberrant Resting-State Functional Brain Connectivity of Insular Subregions in Obstructive Sleep Apnea

The insular cortex is a cortical regulatory area involved in dyspnea, cognition, emotion, and sensorimotor function. Previous studies reported that obstructive sleep apnea (OSA) shows insular tissue damage and abnormal functional connections for the whole insula. The insula can be divided into different subregions with distinct functional profiles, including the ventral anterior insula (vAI) participating in affective processing, dorsal anterior insula (dAI) involved in cognitive processing, and posterior insula (PI) involved in the processing of sensorimotor information. However, the functional connectivity (FC) of these insular subregions in OSA has yet to be established. Hence, the purpose of this study was to explore the resting-state FC of the insular subregions with other brain areas and its relationship with clinical symptoms of OSA. Resting-state functional magnetic resonance imaging data from 83 male OSA patients and 84 healthy controls were analyzed by whole-brain voxel-based FC using spherical seeds from six insular subregions, namely, the bilateral vAI, dAI, and PI, to identify abnormalities in the insular subregions network and related brain regions. Ultimately, the Pearson correlation analysis was carried out between the dysfunction results and the neuropsychological tests. Compared with the healthy control group, the OSA patients exhibited disturbed FC from the dAI to areas relevant to cognition, such as the bilateral cerebellum posterior lobe, superior frontal gyrus, right middle frontal gyrus and middle temporal gyrus; decreased FC from the vAI to areas linked with emotion, such as the bilateral fusiform gyrus, superior parietal lobule, precuneus and cerebellum posterior lobe; and abnormal FC from the PI to the brain regions involved in sensorimotor such as the bilateral precentral gyrus, right superior/middle temporal gyrus and left superior frontal gyrus. The linear regression result showed that the apnea-hypopnea index was positively correlated with the increased FC between the right PI and the right precuneus (after Bonferroni correlation, P < 0.001) In conclusion, the abnormal FC between insular subregions and other brain regions were related to cognitive, emotional and sensorimotor networks in OSA patients. These results may provide a new imaging perspective for further understanding of OSA-related cognitive and affective disorders.

Lateral pharyngoplasty vs. traditional uvulopalatopharyngoplasty for patients with OSA: systematic review and meta-analysis

OBJECTIVES

To compare the efficacy and success rates of lateral pharyngoplasty techniques (LP) vs. uvulopalatopharyngoplasty (UPPP) among adult patients surgically treated for obstructive sleep apnea.

METHODS

A systematic literature review of the last 20 years' papers was conducted using PubMed/Medline, Embase, Web of Science, Scholar, and the Cochrane Library until April 2021. Only full-text English articles comparing LP and UPPP outcomes in adult patients with objective outcomes were included in the study.

RESULTS

We included 9 articles for a total of 312 surgically treated patients with OSA. LP techniques for obstructive sleep apnea were used on 186 (60%) subjects, while 126 patients (40%) were treated with UPPP. Both surgical procedures resulted in significant improvements in apnea-hypopnea index (AHI), Epworth Sleepiness Scale (ESS) score, and lowest oxygen saturation (LOS) (p < 0.001 in all cases). Although better outcomes were reported with lateral pharyngoplasty, the differences were not significant compared to UPPP post-operative results (p > 0.05 in all cases).

CONCLUSIONS

UPPP and LP are both effective surgical procedures in treating OSA in adults. Although not significant, LPs demonstrated improved post-operative outcomes. However, further evidence comparing the surgical effect on patients with OSA is needed to discriminate post-operative outcomes.

Brain function in children with obstructive sleep apnea: a resting-state fMRI study

OBJECTIVE

To explore the neural difference between children with obstructive sleep apnea (OSA) and healthy controls, together with the relation between this difference and cognitive dysfunction of children with OSA.

METHODS

Twenty children with OSA (7.2 ± 3.1 years, apnea hypopnea index (AHI): 16.5 ± 16.6 events/h) and 29 healthy controls (7.7 ± 2.8 years, AHI: 1.7 ± 1.2 events/h) were recruited and matched with age, gender, and handedness. All children underwent resting-state fMRI (rs-fMRI) and T1-wighted imaging. Some children were sedated for MRI scanning. We compared amplitude of low frequency fluctuation (ALFF) and regional homogeneity (ReHo) of children with OSA with those of healthy controls. During resting-state, the former reflects the intensity of the spontaneous neural activities, whereas the latter reflects temporal similarity of the spontaneous neural activities within a local brain region. Pearson correlation analysis was performed between these features of rs-fMRI and cognitive scores among children with OSA.

RESULTS

Compared with controls, children with OSA showed decreased ALFF in the left angular gyrus but increased ALFF in the right insula, and decreased ReHo in the left medial superior frontal gyrus, right lingual gyrus, and left precuneus. Additionally, among children with OSA, the ReHo value in the right lingual gyrus was negatively correlated with FIQ and VIQ, whereas that in the left medial superior frontal gyrus was positively correlated with VIQ.

CONCLUSIONS

Children with OSA presented abnormal neural activities in some brain regions and impaired cognitive functions with the former possibly being the neural mechanism of the latter.

Indications for and Outcomes of Expansion Sphincter Pharyngoplasty to Treat Lateral Pharyngeal Collapse in Patients With Obstructive Sleep Apnea

Importance

The lateral pharyngeal wall is recognized as an important site of upper airway collapse during sleep in patients with obstructive sleep apnea (OSA), and expansion sphincter pharyngoplasty (ESP) may have promising clinical utility in patients with OSA and lateral pharyngeal wall collapse.

Objectives

To evaluate the therapeutic outcomes of ESP in conjunction with other surgical procedures and to investigate indications for ESP in patients with OSA.

Design, Setting, and Participants

Cohort study of 63 patients with OSA diagnosed with lateral pharyngeal collapse under drug-induced sleep endoscopy who underwent ESP combined with tonsillectomy, uvuloplasty, or nasal surgery at Seoul National University Hospital in Seoul, Korea, between March 1, 2015, and December 1, 2016.

Main Outcomes and Measures

The primary outcome measure was the change in the apnea-hypopnea index (AHI) after surgery (AHI represents the number of apnea-hypopnea events per hour). Other outcome measures were differences in the surgical response rates, lowest oxygen saturation, subjective visual analog scale scores for snoring and apnea, and Epworth Sleepiness Scale score.

Results

Fifty of the 63 patients (79%) were male; the mean age was 42.1 (range, 20-54) years, and the mean body mass index (calculated as weight in kilograms divided by height in meters squared) was 27.6 (range, 19.0-32.1). Expansion sphincter pharyngoplasty was performed in patients with OSA with an AHI greater than 15 events per hour, more than 75% retropalatal circumferential narrowing when awake, and narrowed oropharynx due to bulky soft tissue around the lateral pharyngeal wall. In 42 of the 63 patients (67%), ESP was objectively successful in correcting lateral pharyngeal collapse; there was a significant reduction in mean AHI from 35.5 to 17.3 (mean difference, 18.1; 95% CI, 16.3-20.0) and improvement of the lowest mean (SD) oxygen saturation measurement from 78.2% (21.3%) to 86.4% (10.6%) (mean difference, 8.60%; 95% CI, 6.60%-10.60%) 6 months after the operation. The rate of postoperative complications, including pain and bleeding, was minimal after ESP, and a few patients reported an abnormal sensation around the soft palate and swallowing difficulty after ESP.

Conclusions and Relevance

Expansion sphincter pharyngoplasty appears to be a promising surgical technique to reduce lateral pharyngeal collapse in patients with moderate or severe OSA. Clinical data suggest that both severe palatal circumferential narrowing and bulky lateral pharyngeal tissue are favorable surgical indications for ESP in patients with OSA.

The clinical efficacy of relocation pharyngoplasty to improve retropalatal circumferential narrowing in obstructive sleep apnea patients

Lateral pharyngeal wall appears to be a critical culprit of obstructive sleep apnea (OSA) subjects and relocation pharyngoplasty has been expected to be a promising surgical option to correct retropalatal circumferential narrowing in OSA patients. The purpose of our study is to evaluate the therapeutic outcomes of relocation pharyngoplasty and its clinical effectiveness in OSA patients with retropalatal circumferential narrowing. We performed relocation pharyngoplasty combined with nasal surgery in 133 OSA patients with the following characteristics: apnea-hypopnea index (AHI) over 10, retropalatal circumferential narrowing greater than grade I when awake, and redundant soft tissue around the lateral pharyngeal wall. The analysis of surgical success rate was performed with the data of 68 subjects who underwent pre and postoperative polysomnography. The objective success rate of relocation pharyngoplasty was 52.9%, and significant reduction of mean AHI with improvement of lowest SpO2 was seen in 69% of patients 3 months after the surgery. The median AHI was decreased from preoperative 37.3 to postoperative 21.4. Median lowest SpO2 changed from 78.4 to 84.1%. Total sleep time, daytime sleepiness, and visual analogue scale for snoring showed improvement as well. Postoperative complications including pain or bleeding were minimal in 133 subjects and a few patients complained of subtle taste loss. Our data demonstrate that relocation pharyngoplasty can be a favorable surgical option fighting against retropalatal circumferential narrowing.

Changes in insular cortex metabolites in patients with obstructive sleep apnea syndrome

The aim of this study was to investigate the changes in insular cortex metabolites and the correlation with clinical manifestations in patients with obstructive sleep apnea syndrome (OSA). Lateral insular metabolite levels were measured and relevant ratios were calculated in OSA patients and healthy individuals, including N-acetyl aspartate/creatine (NAA/Cr), choline/creatine (Cho/Cr), inositol/creatine (Ins/Cr), glutamate compound/creatine (Glx/Cr), N-acetyl aspartate/choline (NAA/Cho), and lactic acid (Lac). Participants' scores on the Hamilton Anxiety Scale (HAMA), the Hamilton Depression Scale (HAMD), the Pittsburgh Sleep Quality Index (PSQI), and the Epworth Sleepiness Scale (ESS) were also evaluated. Apnea-Hypopnea Index, the lowest arterial oxygen saturation, and the mean arterial oxygen saturation (MSaO2) values were monitored by polysomnography. NAA/Cr, Glx/Cr, and NAA/Cho values in the insular cortex were significantly decreased, whereas HAMA, HAMD, PSQI, and ESS scores were significantly higher in OSA patients compared with the control participants. HAMA and HAMD scores showed a significant negative correlation with the NAA/Cho value in the insular cortex and a positive correlation with PSQI and ESS scores. PSQI scores were correlated positively with the Cho/Cr and Ins/Cr ratios in the left insular cortex, but correlated negatively with the NAA/Cho ratio. The symptoms of anxiety and depression in OSA patients may be associated with insular neuron damage or dysfunction; proton magnetic resonance spectroscopy can provide an objective imaging basis for the early diagnosis and treatment of OSA in clinical practice.

Effects of Habenular Stimulation Frequencies on Obstructive Sleep Apnea Induced by Stimulation of Insular Cortex

Objective

To investigate the effects of high-frequency stimulation of the habenula (Hb) on obstructive sleep apnea (OSA) induced by stimulation of the insular cortex Method. After OSA was induced by stimulating the insular cortex (Ic) with concentric stimulating electrodes at 100 Hz in rats, the Hb was stimulated at different frequencies (50 Hz, 120 Hz, 130 Hz, and 280 Hz). The changes of apnea events and electromyography (EMG) of the genioglossus were compared before and after stimulation of the Hb.

Results

With stimulation of the Ic at 100 Hz, apnea events were successfully induced with disappearance of EMG of the genioglossus. After stimulation of the Hb at 130 Hz, apnea events disappeared with significantly increased genioglossal EMG. However, such a change failed to be found at the stimulation frequencies of 50 Hz, 120 Hz, and 280 Hz.

Conclusion

Stimulation of the Hb at the frequency of 130 Hz could effectively inhibit OSA events induced by stimulation of the Ic.