The development of treatment emergent central sleep apnea (CSA) has been described after almost all obstructive sleep apnea (OSA) therapies. While the course of positive airway pressure (PAP) emergent CSA, is better established; little is known about the natural course of mandibular advancement device (MAD) emergent CSA. Previous reports failed to comment on its natural course or report treatment with advanced ventilator modes such as adaptive servoventilation. We describe spontaneous resolution of MAD emergent CSA in a patient with moderate OSA who refused PAP. We also highlight the need for follow up polysomnography (PSG) after maximal advancement with a MAD and the possible association between MAD emergent CSA and atrial fibrillation. The exact pathophysiology of this phenomenon remains unclear but may relate to high loop gain of the respiratory system resulting in ventilatory overshoot after treatment and atrial fibrillation associated increased susceptibility to periodic ventilation.
Mohan A, Henderson J, Mador MJ. Mandibular advancement device—emergent central sleep apnea can resolve spontaneously: a case report. J Clin Sleep Med 2016;12(1):137–138.
Central sleep apnea (CSA) can be primary (idiopathic) or secondary.1 OSA treatment emergent central sleep apnea has been described after PAP therapy, MAD, and OSA surgeries such as maxillofacial surgery and tracheostomy.2–6 Three prior reports on MAD emergent CSA3–5 failed to comment on its natural course or report treatment with advanced ventilator modes such as adaptive servo ventilation. We report spontaneous resolution of these events in a patient with moderate OSA who refused PAP. We hypothesize that with continued MAD treatment these CSA events can resolve spontaneously, and expectant management may be an option in such cases. We also highlight the need for close clinical and PSG follow up after maximal MAD advancement.
REPORT OF CASE
A 69-year-old male with a past medical history of diabetes, hypertension, coronary artery disease, and atrial fibrillation requiring multiple ablations was referred to our sleep clinic for OSA evaluation. On presentation, he reported poor sleep quality and constant daytime fatigue. His body mass index was 36.5 and neck size was 17.5 inches. His cardiopulmo-nary examination was remarkable for an irregularly irregular heartbeat. His home medications included glipizide, lisinopril, metoprolol, simvastatin, warfarin, and aspirin. His last echo-cardiogram showed mild concentric left ventricular hypertrophy with an ejection fraction > 55%, bi-atrial enlargement, and normal right ventricular size and function with no evidence for pulmonary hypertension. A level 1 polysomnogram demonstrated moderate OSA with associated hypoxemia but no central events (Table 1). Despite strong recommendations, the patient refused PAP due to concerns of claustrophobia. He was subsequently offered a MAD (SomnoDent; SomnoMed, Denton TX). He tolerated maximal mandibular advancement to 7.5 mm (53.7% of total protrusion) over a 3-month period. At this point, a PSG with his MAD showed an AHI that was not significantly different from baseline, but 49% of the respiratory events were central, consistent with treatment-emergent central sleep apnea (Table 1). PAP was offered again, but the patient again refused this therapy as he felt his symptoms had largely resolved with use of his MAD. He was monitored closely for an additional year and a third PSG with his MAD was repeated (Table 1). This showed very mild residual OSA with complete resolution of his central events. Of note, his BMI was stable during this period (lowest noted was 35.5 at the end of 1 year). He was in sinus rhythm during all 3 PSGs. However, long-term Holter monitoring prior to his first study had shown intermittent bouts of atrial fibrillation. The patient had no clinical episodes of paroxysmal atrial fibrillation during the year of treatment with his MAD.
Summary of sleep study reports.
Recurrent apneic events occurring in the absence of respiratory effort is called central sleep apnea.1 MAD-emergent central apneas have been described in the literature since 2006.3 The prevalence and natural history of MAD-emergent central sleep apnea is unknown. Our report highlights that these apneas, similar to those seen with PAP therapy, can resolve over time. Given that spontaneous resolution is noted in 50% to 75% of PAP-emergent central apneas2 after several months of PAP therapy, we suspect spontaneous resolution of MAD-emergent central apneas occurs more frequently than anticipated. Since MADs are advanced slowly, repeat sleep studies documenting their efficacy are not usually performed for at least 3 months after treatment initiation. Thus, if MAD-emergent CSA behaves similarly to PAP-emergent CSA, central events may have occurred and resolved by the time the MAD efficacy study is performed. However, unlike PAP therapy which is effective immediately, the gradual advancement of MAD devices means that treatment effectiveness may not occur for some time after therapy is initiated. This likely explains why central events were still present after 3 months of therapy and why they resolved spontaneously after more time at effective therapy. The key to resolution with PAP therapy appears to be strict adherence with therapy.
Furthermore, we postulate an association with comorbid cardiac disease especially atrial fibrillation. Atrial fibrillation has been a comorbid disease in most reported cases.4,5 However, its association with treatment-emergent CSA development has not been well established, although it is a well-established risk factor for the development of non-treatment emergent CSA. It may work in conjunction with other possible mechanisms, such as high loop gain of the respiratory system resulting in ventilatory overshoot after treatment.
Reports such as ours are needed to understand the phenomenon of MAD emergent central sleep apnea, as MAD becomes a first line therapy for treatment of mild to moderate sleep apnea.
This was not an industry supported study. The authors have indicated no financial conflicts of interest.