Andrew T. Ng

Cephalometry and prediction of oral appliance treatment outcome

RationalePredicting which patients with obstructive sleep apnea (OSA) will be successfully treated with mandibular advancement splints (MAS) remains elusive. Developing simple daytime measurements and tests to predict treatment outcome would enhance MAS treatment.ObjectiveThe purpose of this study was to assess the clinical utility of anthropomorphic measurements and cephalometric X-rays in the prediction of MAS treatment outcome in OSA.MethodsAnthropomorphic measurements and cephalometric X-rays from 72 OSA patients who had presented to a tertiary referral sleep clinic were analyzed retrospectively.ResultsTreatment response was defined as ≥50% reduction in Apnea/Hypopnea Index (AHI; criterion 1); ≥50% reduction and residual AHI less than 20/h (criterion 2); ≥50% reduction in AHI and residual AHI less than 10/h (criterion 3); and ≥50% reduction in AHI and residual AHI less than 5/h (criterion 4). This was done to reflect the differences in the clinical definition of treatment success in the literature. A good response occurred in 56% (40 patients) according to criterion 1; 54% (39 patients) according to criterion 2; 46% (33 patients) according to criterion 3; or 39% (28 patients) according to criterion 4. Age and gender were found to be significant predictors for criteria 1 and 2. Age and soft palate length were found to be significant predictors for criteria 3 and 4. Equations to predict MAS treatment response were derived as equations were to predict final AHI.ConclusionsCertain cephalometric and anthropomorphic measurements impact on MAS treatment outcome. This study adds to the current literature and implies that MAS success is (to some degree) related to anatomical characteristics.

Oral Appliance Therapy for Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a common disorder characterized by repetitive, complete or partial closure of the upper airway during sleep, resulting in sleep fragmentation and oxygen desaturation. The disorder causes significant morbidity, particularly in terms of impairment of daytime functioning and the impact this has on quality of life. There is also evidence that links OSA to long-term cardiovascular morbidity, including hypertension, myocardial infarction, and stroke, and increased risk of motor vehicle accidents. There is clear evidence that effective treatment of OSA provides major benefit to patients.Nasal continuous positive airway pressure (CPAP) is the current treatment of choice, but its cumbersome nature makes tolerance and compliance less than optimal. This gives rise to the need for other alternatives that are equally effective, but more tolerable. There is growing interest in the use of oral appliances to treat snoring and OSA. The rationale is that advancement of the mandible and tongue impacts positively on upper airway caliber and function. There are many such types of appliances, and they have potential advantages over CPAP in that they are unobtrusive, make no noise, do not need a power source, and are potentially less costly.There is a growing evidence base to support the use of oral appliances in the management of OSA. Recent evidence from randomized controlled trials indicates that oral appliance therapy is effective in controlling OSA in up to 50% of patients, including some patients with more severe forms of OSA. This is associated with a significant improvement in symptoms, including snoring and daytime sleepiness. This evidence is strong for short term, and emerging for long-term treatment of OSA with oral appliances. Whilst direct comparisons with CPAP indicate the superiority of CPAP overall, similar outcomes between the two treatments appear to be achieved in a substantial subgroup of patients. Patient acceptance has, in general, been in favor of oral appliances.Notwithstanding the expanding role of oral appliance therapy, there are a number of limitations that are yet to be overcome. Key issues include the inability to reliably predict treatment outcome, the apparent need for an acclimatization period to attain maximal efficacy of treatment, uncertainty about selection of the appropriate ‘dosage’ of mandibular advancement required to control OSA in the individual patient, uncertainty about the influence of appliance design on treatment outcome and adverse effects, adherence to treatment, and potential long-term complications of therapy. These issues require resolution before oral appliance therapy can surpass CPAP as first-line treatment for OSA.

Oral Appliance Treatment Response and Polysomnographic Phenotypes of Obstructive Sleep Apnea.

STUDY OBJECTIVES Mandibular advancement splints (MAS) are an effective treatment for obstructive sleep apnea (OSA); however, therapeutic response is variable. Younger age, female gender, less obesity, and milder and supine-dependent OSA have variably been associated with treatment success in relatively small samples. Our objective was to utilize a large cohort of MAS treated patients (1) to compare efficacy across patients with different phenotypes of OSA and (2) to assess demographic, anthropometric, and polysomnography variables as treatment response predictors. METHODS Retrospective analysis of MAS-treated patients participating in clinical trials in sleep centers in Sydney, Australia between years 2000-2013. All studies used equivalent customized two-piece MAS devices and treatment protocols. Treatment response was defined as (1) apnea-hypopnea index (AHI) < 5/h, (2) AHI < 10/h and ≥ 50% reduction, and (3) ≥ 50% AHI reduction. RESULTS A total of 425 patients (109 female) were included (age 51.2 ± 10.9 years, BMI 29.2 ± 5.0 kg/m2). MAS reduced AHI by 50.3% ± 50.7% across the group. Supine-predominant OSA patients had lower treatment response rates than non-positional OSA (e.g., 36% vs. 59% for AHI < 10/h). REM-predominant OSA showed a lower response rate than either NREM or non-stage dependent OSA. In prediction modelling, age, baseline AHI, and anthropometric variables were predictive of MAS treatment outcome but not OSA phenotype. Gender was not associated with treatment outcome. CONCLUSION Lower MAS treatment response rates were observed in supine and REM sleep. In a large sample, we confirm that demographic, anthropometric, and polysomnographic data only weakly inform about MAS efficacy, supporting the need for alternative objective prediction methods to reliably select patients for MAS treatment.

Tubulointerstitial nephritis and uveitis: a rare cause of renal failure

Abstract We report two cases of tubulointerstitial nephritis and uveitis syndrome occurring in adults. Both patients had the characteristic marked constitutional symptoms, uveitis, and renal failure. After treatment with systemic corticosteroids, renal function improved. This is contrary to previous reports that have indicated a poor prognosis in adults.