Takumi Ogawa

Soft palate length and upper airway relationship in OSA and non-OSA subjects

BACKGROUND The narrowest area of the airway between the posterior nasal opening and the epiglottis is usually located in the retro palatal area. Many consider this the most likely site of airway obstruction during an obstructive sleep apnea (OSA) event. The aim of this study was to investigate the differences in soft palate and airway length between OSA and non-OSA patients. METHODS In this study, we analyzed the ratio of the soft palate and the upper airway length in 45 consecutive patients. Twenty-five had an Apnea-Hypoapnea Index of more than five events per hour and were classified in the OSA group (male, 19; female, 6). These patients were compared with 20 normal controls (male, 12; female, 8). Controls who complained of snoring did have sleep studies (n=5). The other fifteen controls were clinically asymptomatic and did not have sleep studies. Medical computed tomography scans were taken to determine the length of the upper airway and the soft palate length measured in the midsagittal image. RESULTS Soft palate length was significantly larger in OSA patients compared to controls (p=0.009), and in men compared to women (p=0.002). However, there were no differences in airway length. The soft palate length, as a percent of oropharyngeal airway length, was significantly larger in OSA patients compared to controls (p= <0.0001) and in men compared to women (p=0.02). Soft palate length increases significantly with age by 0.3 mm per year in males (after adjustment for body mass index (BMI) and OSA). Soft palate length as a percent of airway length is larger in OSA patients and increases significantly with BMI in males only after adjusting for age. CONCLUSION In this study, OSA patients had a longer soft palate in proportion to their oropharyngeal airway compared to controls as well as men compared to women. This proportion could be used for identifying patients at risk for OSA in combination with age.

Correlation between retroglossal airway size and body mass index in OSA and non-OSA patients using cone beam CT imaging

Most obstructive sleep apnea (OSA) patients are overweight, and OSA is substantially more common in obese individuals. In morbidly obese patients, at least 70% suffer from OSA. However, the exact mechanism by which obesity causes OSA is unclear. The aim of this study is to evaluate the retroglossal airway configuration quantitatively and to make clear the relationship between Body mass index (BMI) and airway configuration. This retrospective study included 15 OSA patients (male = 11; female = 4) and 14 normal controls (male = 8; female = 6). We studied the airway configuration on an axial slice at the level of the anterior–inferior corner of the second cervical vertebra. Maximum anterior–posterior diameter (AP) and lateral width (LW) of the airway were measured, and the square area (SA) was calculated. The airway cross-section area (AWA) was also measured, and then the AWA/SA ratio was calculated. AP, LW, and AWA were not statistically significantly different between controls and OSA patients. On the other hand, the AWA/SA ratio in OSA patients was 8.8% statistically significantly smaller than in controls after adjusting for sex, age, and BMI. In this sample, there was a negative correlation between age and the AWA/SA ratio but only in the OSA group. The AWA/SA ratio was significantly negatively correlated with OSA status (R = −0.5; p = 0.008) after adjusting for BMI and age. In this present study, we could evaluate the retroglossal airway configuration quantitatively. The AWA/SA ratio was correlated with OSA status after adjusting for BMI and age.

Influence of tongue/mandible volume ratio on oropharyngeal airway in Japanese male patients with obstructive sleep apnea

OBJECTIVES The objective of this study was to investigate the influence on the upper airway of the size ratio of tongue and mandible (T/M ratio) with 3D reconstructed models from computed tomography (CT) data. STUDY DESIGN The subjects were 40 OSA male patients. The age of the patients ranged from 25 to 77 years, with an average age of 52.6 ± 12.5 years. The body mass index (BMI) of the patients ranged from 20.1 to 35.8 kg/m(2), with an average BMI of 25.4 ± 3.4 kg/m(2). All patients underwent a full-night polysomnography. The mean AHI for our subjects was 23.6 ± 18.3 events per hour. CT imaging examinations were carried out in each patient. The mandible and airway volume (between posterior nasal spine [PNS] and the tip of the epiglottis) were segmented based on Hounsfield units, automatically or semi-automatically, and their volume was calculated from the number of voxels. The tongue was carefully outlined, and the inside of the tongue was smeared on each of the axial, frontal, and sagittal planes with a semi-automatic segmentation tool. The tongue/mandible (T/M) ratio was calculated from the volume of the mandible and the tongue. In addition, we investigated simple correlations between our anatomical variables and BMI, age, and AHI. RESULTS In this study, the mean tongue and mandible volume were 79.00 ± 1.06 cm(3) and 87.80 ± 1.21 cm(3), respectively. As BMI increases, tongue volume increases (P = .004) and airway volume decreases (P = .021). However, no significant correlation was found between severity of OSA (AHI) and other variables. On the other hand, there was a negative correlation between airway volume and T/M ratio (P = .046). CONCLUSION As tongue volume increases with BMI, the posterior airway is affected, and thus is likely to be involved in the development of OSA; however, in this study there was no correlation between the severity of sleep apnea (AHI) and other variables in the study.

Cervical CT derived neck fat tissue distribution differences in Japanese males and females and its effect on retroglossal and retropalatal airway volume

OBJECTIVE The objective of this study was to investigate the difference of neck fat tissue distribution by sex and its correlation with retropalatal and retroglossal airway. STUDY DESIGN A total of 38 consecutive patients (male: 19; female: 19) who received a CT scan were compared in the retroglossal region and at the narrowest cross section of the airway. Retroglossal fat tissue volume (FV) was segmented with Amira software and separated into subcutaneous and internal fat volume (SFV, IFV). These volumes were normalized by retroglossal neck volume (NV). RESULTS Men had 51.9% more IFV/NV and 64.4% less SFV/NV compared with women. Age-adjusted BMI was negatively correlated with retroglossal airway volume (normalized by NV) and with the lateral width of the smallest cross-section airway (LW) in females. In males the IFV/NV was negatively correlated with LW, after adjusting for BMI and age. CONCLUSION Upper airway collapsibility analysis is needed to rule out whether increased BMI or IFV causes an increase in airway collapsibility.

A case of obstructive sleep apnoea with anterior cervical osteophytes.

Osteophytes of the cervical spine are usually seen in elderly adults. When prominent, they have been blamed for dysphagia, cough, dysphonia and dyspnoea. This paper reports on an obstructive sleep apnoea (OSA) patient with cervical spinal osteophytes, one cause of airway obstruction. A 75-year-old male complained of pronounced snoring. The diagnosis was mild OSA, apnoea hypopnoea index was 9.4. Patient reported no restrictions in neck movements, experiences of neck pain or neck trauma. Previously, patient underwent a tonsillectomy due to discomfort in the pharyngeal region. A lateral cephalometric image was taken to observe airway before oral appliance therapy. The image revealed the presence of large osteophytes or sclerotic enthesopathy, lying on anterior surfaces from the fourth to seventh cervical vertebrae. A computed tomography (CT) image revealed the relationship of airway position to the spine. In the reconstructed three-dimensional (3D) image, the airway appeared displaced to the right of the craniomandiblar bone, with the hyoid bone similarly displaced in a manner to that of the airway. The spine also appeared displaced to the left side ofcraniomandiblar bone. Additionally, the 3D image revealed calcification of the stylohyoideum ligament and ligamentum nuchae. This present case highlights the necessity of CT examination for OSA patients. There were several ligament calcifications in the head and neck region. Cervical spine osteophytes, as a component of Forestiers or cervical spine disease, have been associated with dysphagia and dysphonia. It was reported that bilateral vocal cord paralysis was caused by osteophytes compressing the post-cricoid area of larynx.

Investigation of trends and characteristics in patients with obstructive sleep apnea

BackgroundOral appliance (OA) therapy for obstructive sleep apnea (OSA) has only been part of Japan’s National Health care coverage plan since 2004. Subsequently, not enough time has passed to establish the medical trends and characteristics of OSA patients in Japanese Dental Hospitals.AimThe aim of this study was to investigate the medical trends and the characteristics in patients with OSA who visited our clinic, and to compare our findings with previous studies.Setting and designEpidemiological survey (retrospective study).Materials and methodsTwo hundred and one patients were recruited at the Internal Medicine Division in the Tsurumi University Dental Hospital from February 2006 to December 2008, consecutively. Patients received a medical interview, and a detailed sleep analysis that included a polysomnography (PSG) to verify the exact nature of their condition. The efficacy of OA was assessed in 49 patients who wore an OA and underwent PSG.ResultsOf all subjects, 141 patients visited the Prosthodontic Division to receive OA therapy, 38 patients were treated or received a follow up examination in the Internal Medicine Division. The dropout rate was 10.4% in the all subjects, 17.0% in patients who visited the Prosthodontic Division. The male-to-female ratio was 3.3:1, 3.0:1 in patients who visited the Prosthodontic Division. In addition, females had a lower rate of OAS severity than males. In our patients, the major complication was hypertension and cardiac disease. The success rate of OA was 75.5%.ConclusionThis approach allowed us to reveal some of the trends and characteristics in our patients.