Central Sleep Apnea due to Other Medical Disorders

Diagnosis and management of central sleep apnea syndrome

Introduction: Central sleep apnea (CSA) syndrome has gained a considerable interest in the sleep field within the last 10 years. It is overrepresented in particular subpopulations such as patients with stroke or heart failure. Early detection and diagnosis, as well as appropriate treatment of central breathing disturbances during sleep remain challenging. Areas covered: Based on a systematic review of CSA in adults the clinical evidence and polysomnographic patterns useful for discerning central from obstructive events are discussed. Current therapeutic indications of CSA and perspectives are presented, according to the type of respiratory disturbances during sleep, alterations in blood gases and ventilatory control. Expert opinion: The precise identification of central events during polysomnographic recording is mandatory. Therapeutic choices for CSA depend on the typology of respiratory disturbances observed by polysomnography, changes in blood gases and ventilatory control. In CSA with normocapnia and ventilatory instability, adaptive servo-ventilation is recommended. In CSA with hypercapnia and/or rapid-eye movement sleep hypoventilation, non-invasive ventilation is required. Further studies are required as strong evidence is lacking regarding the long-term consequences of CSA and the long-term impact of current treatment strategies.

Sleep-Disordered Breathing in People with Multiple Sclerosis: Prevalence, Pathophysiological Mechanisms, and Disease Consequences

Sleep problems are common in people with multiple sclerosis (MS). Reported prevalence rates of sleep-disordered breathing (SDB) vary between 0 and 87%. Differences in recruitment procedures and study designs likely contribute to the wide variance in reported prevalence rates of SBD in MS. This can make attempts to compare SDB rates in people with MS to the general population challenging. Little is known about the pathophysiological mechanisms that contribute to SDB in people with MS or whether MS contributes to SDB disease progression. However, compared to the general obstructive sleep apnea (OSA) population, there are clear differences in the clinical phenotypes of SDB in the MS population. For instance they are typically not obese and rates of SDB are often comparable or higher to the general population, despite the high female predominance of MS. Thus, the risk factors and pathophysiological causes of SDB in people with MS are likely to be different compared to people with OSA who do not have MS. There may be important bidirectional relationships between SDB and MS. Demyelinating lesions of MS in the brain stem and spinal cord could influence breathing control and upper airway muscle activity to cause SDB. Intermittent hypoxia caused by apneas during the night can increase oxidative stress and may worsen neurodegeneration in people with MS. In addition, inflammation and changes in cytokine levels may play a key role in the relationship between SDB and MS and their shared consequences. Indeed, fatigue, neurocognitive dysfunction, and depression may worsen considerably if both disorders coexist. Recent studies indicate that treatment of SDB in people with MS with conventional first-line therapy, continuous positive airway pressure therapy, can reduce fatigue and cognitive impairment. However, if the causes of SDB differ in people with MS, so too may the optimal therapy. Thus, many questions remain concerning the relationship between these two disorders and the underlying mechanisms and shared consequences. Improved understanding of these factors has the potential to unlock new therapeutic targets.

Central sleep apnea in multiple sclerosis: a pilot study

PURPOSE

The purpose of the present study is to investigate sleep-disordered breathing and symptoms of sleepiness in a consecutive clinical cohort of multiple sclerosis (MS) patients.

METHODS

Twenty-one (16 females) community-dwelling adults aged 18-75 years with MS and an Expanded Disability Status Scale score between 2 and 6 were recruited consecutively from an academic teaching hospital MS clinic. Participants performed a home sleep study (ResMed ApneaLink Plus) to objectively quantify sleep-disordered breathing. Subjective sleepiness and its impact were assessed using the Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index, and Functional Outcomes of Sleep Questionnaire.

RESULTS

Three (one female) of the 19 participants who completed home overnight testing had central sleep apnea (median apnea-hypopnea index = 15 [range = 8-36] events/h sleep, median nadir SaO₂ = 88 % [range = 81-88]). There were no cases of obstructive sleep apnea. Thirty-three percent of participants reported excessive daytime sleepiness, and 71% reported poor sleep quality.

CONCLUSIONS

Home sleep testing was well tolerated, and a high proportion of central rather than obstructive sleep apnea was observed in a clinical MS sample. Possible reasons include brainstem or spinal cord lesions from MS affecting the control of breathing. Poor sleep quality and daytime sleepiness were common in this group.