Daniel A. Barone

A randomised controlled trial on the effect of mask choice on residual respiratory events with continuous positive airway pressure treatment

INTRODUCTION It has been found that mask style can affect the amount of continuous positive airway pressure (CPAP) required to reduce an apnoea/hyponoea index (AHI) to < 5/h on a titration study. However, it was not previously known whether switching from one CPAP mask style to another post titration could affect the residual AHI with CPAP. The purpose of this study was to investigate the differences in residual AHI with CPAP treatment between oronasal and nasal masks. METHODS Twenty-one subjects (age mean (M)=62.9, body mass index (BMI) M=29.6 kg/m2) were randomised (14 subjects completed the protocol) to undergo an in-laboratory CPAP titration with either a nasal mask or an oronasal mask. Subjects were then assigned this mask for 3weeks of at-home CPAP use with the optimal treatment pressure determined on the laboratory study (CPAP M=8.4 cm of H2O). At the end of this 3-week period, data were collected from the CPAP machine and the subject was given the other mask to use with the same CPAP settings for the next 3weeks at home (if the nasal mask was given initially, the oronasal one was given later and vice versa). On completion of the second 3-week period, data on residual AHI were again collected and compared with the first 3-week period on CPAP. RESULTS A Wilcoxon Signed-Rank Test (two-tailed) revealed that residual AHI with CPAP treatment was significantly higher with the oronasal compared with the nasal mask (z = -3.296, p<0.001). All 14 subjects had a higher residual AHI with the oronasal versus nasal mask, and 50% of the subjects had a residual AHI >10/h in the oronasal mask condition, even though all of these subjects were titrated to an AHI of < 5/h in the laboratory. CONCLUSION A higher residual AHI was seen in all patients with the use of an oronasal mask compared with a nasal mask. Switching to an oronasal mask post titration results in an increase in residual AHI with CPAP treatment, and pressure adjustment may be warranted.

Stroke and Obstructive Sleep Apnea: A Review

Obstructive sleep apnea (OSA) has been found to be an independent risk factor for stroke in large epidemiological studies. The mechanisms underlying this relationship have been investigated over the past 2–3 decades, with a particular focus on identifying pathophysiological pathways and risk modification strategies. Despite the advancements made, the specific understanding of the implicated mechanisms is still limited. This brief review focuses on presenting some of the epidemiological evidence of the linkage between OSA and stroke, discussing mechanistic pathways and the potential effect of OSA treatment in modulating the risk for stroke in these patients. Future directions for research in this field are also discussed.

Autonomic dysfunction in isolated rapid eye movement sleep without atonia

OBJECTIVES Autonomic dysfunction has been demonstrated in patients with rapid eye movement sleep behavior disorder utilizing heart rate variability parameters. We hypothesized that isolated rapid eye movement sleep without atonia is similarly associated with autonomic dysfunction as demonstrated by a reduction in heart rate variability. METHODS An evaluation of 120 records demonstrating rapid eye movement sleep without atonia during polysomnography was performed. Many (n=99) were discarded owing to factors potentially affecting heart rate variability. The remaining 21 records were matched with 21 records of patients demonstrating normal REM atonia, and subjected to electrocardiogram analysis. The parameters measured included R to R interval (RR) length, RR standard deviation, heart rate variability power, and very low frequency, low frequency, and high frequency bands. RESULTS Autonomic dysfunction was seen in patients with isolated rapid eye movement sleep without atonia as denoted by a reduction in heart rate variability compared to those with normal REM atonia. Significant differences between the groups were demonstrated in RR standard deviation (mean difference=0.1502 ± 0.317, 95% confidence interval [95% CI]=0.006, 0.295, p=0.042), heart rate variability power (mean difference=0.3005 ± 0.635, 95% CI=0.011, 0.589, p=0.042), and the low frequency band (mean difference=0.3166 ± 0.616 ms(2), 95% CI=0.036, 0.597, p=0.029), and a borderline significant reduction in the high frequency band (mean difference=0.3121 ± 0.686 ms(2), 95% CI=0.000, 0.624, p=0.050). CONCLUSIONS Our data confirms the hypothesis that heart rate variability is reduced in patients with isolated rapid eye movement sleep without atonia. The values obtained are consistent with previous findings in rapid eye movement behavior sleep disorder patients. SIGNIFICANCE This is the first report of autonomic dysfunction in isolated rapid eye movement sleep without atonia, revealing the need for further evaluation of the clinical significance and potential implications of this finding.

Neurologic Diseases and Sleep

Sleep disorders and neurologic illness are common and burdensome in their own right; when combined, they can have tremendous negative impact at an individual level as well as societally. The socioeconomic burden of sleep disorders and neurologic illness can be identified, but the real cost of these conditions lies far beyond the financial realm. There is an urgent need for comprehensive care and support systems to help with the burden of disease. Further research in improving patient outcomes in those who suffer with these conditions will help patients and their families, and society in general.

Sleep disturbances in voltage-gated potassium channel antibody syndrome

Voltage-gated potassium channels (VGKCs) are a family of membrane proteins responsible for controlling cell membrane potential. The presence of antibodies (Ab) against neuronal VGKC complexes aids in the diagnosis of idiopathic and paraneoplastic autoimmune neurologic disorders. The diagnosis of VGKC Ab-associated encephalopathy (VCKC Ab syndrome) should be suspected in patients with subacute onset of disorientation, confusion, and memory loss in the presence of seizures or a movement disorder. VGKC Ab syndrome may present with sleep-related symptoms, and the purpose of this communication is to alert sleep and neurology clinicians of this still-under-recognized condition. In this case, we are presenting the VGKC Ab syndrome which improved after treatment with solumedrol. The prompt recognition and treatment of this condition may prevent the morbidity associated with cerebral atrophy and the mortality associated with intractable seizures and electrolyte disturbances.

Rapid eye movement sleep behavior disorder and the link to alpha-synucleinopathies

Rapid eye movement (REM) sleep behavior disorder (RBD) involves REM sleep without atonia in conjunction with a recurrent nocturnal dream enactment behavior, with vocalizations such as shouting and screaming, and motor behaviors such as punching and kicking. Secondary RBD is well described in association with neurological disorders including Parkinsons disease (PD), multiple system atrophy (MSA), and other conditions involving brainstem structures such as tumors. However, RBD alone is now considered to be a potential harbinger of later development of neurodegenerative disorders, in particular PD, MSA, dementia with Lewy bodies (DLB), and pure autonomic failure. These conditions are linked by their underpinning pathology of alpha-synuclein protein aggregation. In RBD, it is therefore important to recognize the potential risk for later development of an alpha-synucleinopathy, and to investigate for other potential causes such as medications. Other signs and symptoms have been described in RBD, such as orthostatic hypotension, or depression. While it is important to recognize these features to improve patient management, they may ultimately provide clinical clues that will lead to risk stratification for phenoconversion. A critical need is to improve our ability to counsel patients, particularly with regard to prognosis. The ability to identify who, of those with RBD, is at high risk for later neurodegenerative disorders will be paramount, and would in addition advance our understanding of the prodromal stages of the alpha-synucleinopathies. Moreover, recognition of at-risk individuals for neurodegenerative disorders may ultimately provide a platform for the testing of possible neuroprotective agents for these neurodegenerative disorders.

Improvement of Sleepiness in Connective Tissue Disorders Following H1/H2 Blockade

Improvement of Sleepiness in Connective Tissue Disorders Following H1/H2 Blockade This report describes two patients with connective tissue disorders, Ehlers-Danlos syndrome and systemic lupus erythematosus (SLE), presenting with excessive daytime sleepiness. It has been suggested that these conditions involve activation of mast cells, which in turn is at least partially responsible for the symptoms of sleepiness. The two patients described were treated with H1 and H2 histamine blockers, and had experienced profound improvement in their subjective symptoms. These cases will hopefully inspire further research and discussion in this area.

A 45-Year-Old Man With Delayed Onset of OSA Events During Polysomnography

A 45-year-old man with a medical history that included asthma and chronic nasal congestion presented for an evaluation of possible OSA. He reported loud snoring, witnessed apneas in sleep, and daytime sleepiness. The patients score on the Epworth Sleepiness Scale was 12 of 24, indicating excessive sleepiness. His nasal congestion had been treated with frequent use of an over-the-counter nasal decongestant.

Alternative devices for obstructive sleep apnea

Obstructive sleep apnea (OSA) is a relatively common condition which is most often treated with continuous positive airway pressure (CPAP). Given the compliance issues associated with CPAP, it is important for neurologists (and anyone who treats OSA) to be aware of what other treatment devices exist for this disease. This article reviews mandibular advancement devices, nasal expiratory airway pressure devices, hypoglossal nerve stimulators, and oral pressure therapy devices in terms of their mechanism of action, efficacy, and practicality.