Justine A. Aaronson

Obstructive sleep apnea is related to impaired cognitive and functional status after stroke

STUDY OBJECTIVES Obstructive sleep apnea (OSA) is a common sleep disorder in stroke patients and is associated with prolonged hospitalization, decreased functional outcome, and recurrent stroke. Research on the effect of OSA on cognitive functioning following stroke is scarce. The primary objective of this study was to compare stroke patients with and without OSA on cognitive and functional status upon admission to inpatient rehabilitation. DESIGN Case-control study. SETTING AND PATIENTS 147 stroke patients admitted to a neurorehabilitation unit. INTERVENTIONS N/A. MEASUREMENTS All patients underwent sleep examination for diagnosis of OSA. We assessed cognitive status by neuropsychological examination and functional status by two neurological scales and a measure of functional independence. RESULTS We included 80 stroke patients with OSA and 67 stroke patients without OSA. OSA patients were older and had a higher body mass index than patients without OSA. OSA patients performed worse on tests of attention, executive functioning, visuoperception, psychomotor ability, and intelligence than those without OSA. No differences were found for vigilance, memory, and language. OSA patients had a worse neurological status, lower functional independence scores, and a longer period of hospitalization in the neurorehabilitation unit than the patients without OSA. OSA status was not associated with stroke type or classification. CONCLUSIONS Obstructive sleep apnea (OSA) is associated with a lower cognitive and functional status in patients admitted for stroke rehabilitation. This underlines the importance of OSA as a probable prognostic factor, and calls for well-designed randomized controlled trials to study its treatability.

Effects of Continuous Positive Airway Pressure on Cognitive and Functional Outcome of Stroke Patients with Obstructive Sleep Apnea : A Randomized Controlled Trial

STUDY OBJECTIVES Obstructive sleep apnea (OSA) in stroke patients is associated with worse functional and cognitive status during inpatient rehabilitation. We hypothesized that a four-week period of continuous positive airway pressure (CPAP) treatment would improve cognitive and functional outcomes. METHODS We performed a randomized controlled trial in stroke patients admitted to a neurorehabilitation unit. Patients were assigned to rehabilitation treatment as usual (control group) or to CPAP treatment (CPAP group). Primary outcomes were cognitive status measured by neuropsychological examination, and functional status measured by two neurological scales and a measure of activities of daily living (ADL). Secondary measures included sleepiness, sleep quality, fatigue, and mood. Tests were performed at baseline and after the four-week intervention period. RESULTS We randomly assigned 20 patients to the CPAP group and 16 patients to the control group. The average CPAP compliance was 2.5 hours per night. Patients in the CPAP group showed significantly greater improvement in the cognitive domains of attention and executive functioning than the control group. CPAP compliance was associated with greater improvement in cognitive functioning. CPAP did not result in measurable improvement on measures of neurological status or ADL, or on any of the secondary measures. CONCLUSIONS CPAP treatment improves cognitive functioning of stroke patients with OSA. COMMENTARY A commentary on this article appears in this issue on page 467.

Diagnostic Accuracy of Nocturnal Oximetry for Detection of Sleep Apnea Syndrome in Stroke Rehabilitation

Background and Purpose— Sleep apnea syndrome (SAS) is a common sleep disorder in stroke patients and is associated with decreased recovery and increased risk of recurrent stroke and mortality. The standard diagnostic test for SAS is poly(somno)graphy, but this is often not feasible in stroke rehabilitation settings. This study investigated the diagnostic value of nocturnal oximetry for screening SAS in stroke rehabilitation. Methods— Fifty-six stroke patients underwent nocturnal polygraphy and oximetry. Sensitivity, specificity, and positive and negative predictive values for the oxygen desaturation index were calculated. Patient and sleep characteristics were used to develop a predictive model of apnea–hypopnea index. Results— Forty-six percent of the stroke patients had SAS. The majority of SAS patients was male, older, and had a higher body mass index than patients without SAS. Sensitivity, specificity, and positive and negative predictive values for the oxygen desaturation index ≥15 were, respectively, 77%, 100%, 100%, and 83%. Oxygen desaturation index predicted 87% of the variance in the apnea–hypopnea index. Patient characteristics did not add significantly to the prediction model. Conclusion— Nocturnal oximetry is an accurate diagnostic screening instrument for the detection of SAS in stroke patients.

Brain training improves recovery after stroke but waiting list improves equally : A multicenter randomized controlled trial of a computer-based cognitive flexibility training

Background Brain training is currently widely used in an attempt to improve cognitive functioning. Computer-based training can be performed at home and could therefore be an effective add-on to available rehabilitation programs aimed at improving cognitive functioning. Several studies have reported cognitive improvements after computer training, but most lacked proper active and passive control conditions. Objective Our aim was to investigate whether computer-based cognitive flexibility training improves executive functioning after stroke. We also conducted within-group analyses similar to those used in previous studies, to assess inferences about transfer effects when comparisons to proper control groups are missing. Methods We conducted a randomized controlled, double blind trial. Adults (30–80 years old) who had suffered a stroke within the last 5 years were assigned to either an intervention group (n = 38), active control group (i.e., mock training; n = 35), or waiting list control group (n = 24). The intervention and mock training consisted of 58 half-hour sessions within a 12-week period. Cognitive functioning was assessed using several paper-and-pencil and computerized neuropsychological tasks before the training, immediately after training, and 4 weeks after training completion. Results and conclusions Both training groups improved on training tasks, and all groups improved on several transfer tasks (three executive functioning tasks, attention, reasoning, and psychomotor speed). Improvements remained 4 weeks after training completion. However, the amount of improvement in executive and general cognitive functioning in the intervention group was similar to that of both control groups (active control and waiting list). Therefore, this improvement was likely due to training-unspecific effects. Our results stress the importance to include both active and passive control conditions in the study design and analyses. Results from studies without proper control conditions should be interpreted with care.

The effect of obstructive sleep apnea and treatment with continuous positive airway pressure on stroke rehabilitation: rationale, design and methods of the TOROS study

BackgroundObstructive sleep apnea is a common sleep disorder in stroke patients. Obstructive sleep apnea is associated with stroke severity and poor functional outcome. Continuous positive airway pressure seems to improve functional recovery in stroke rehabilitation. To date, the effect of continuous positive airway pressure on cognitive functioning in stroke patients is not well established. The current study will investigate the effectiveness of continuous positive airway pressure on both cognitive and functional outcomes in stroke patients with obstructive sleep apnea.Methods/DesignA randomized controlled trial will be conducted on the neurorehabilitation unit of Heliomare, a rehabilitation center in the Netherlands. Seventy stroke patients with obstructive sleep apnea will be randomly allocated to an intervention or control group (n = 2×35). The intervention will consist of four weeks of continuous positive airway pressure treatment. Patients allocated to the control group will receive four weeks of treatment as usual. Outcomes will be assessed at baseline, immediately after the intervention and at two-month follow-up.In a supplementary study, these 70 patients with obstructive sleep apnea will be compared to 70 stroke patients without obstructive sleep apnea with respect to cognitive and functional status at rehabilitation admission. Additionally, the societal participation of both groups will be assessed at six months and one year after inclusion.DiscussionThis study will provide novel information on the effects of obstructive sleep apnea and its treatment with continuous positive airway pressure on rehabilitation outcomes after stroke.Trial registrationTrial registration number: Dutch Trial Register NTR3412

The influence of computer-based cognitive flexibility training on subjective cognitive well-being after stroke: A multi-center randomized controlled trial

Background Stroke can result in cognitive complaints that can have a large impact on quality of life long after its occurrence. A number of computer-based training programs have been developed with the aim to improve cognitive functioning. Most studies investigating their efficacy used only objective outcome measures, whereas a reduction of subjective cognitive complaints may be equally important for improving quality of life. A few studies used subjective outcome measures but were inconclusive, partly due to methodological shortcomings such as lack of proper active and passive control groups. Objective The aim of the current study was to investigate whether computer-based cognitive flexibility training can improve subjective cognitive functioning and quality of life after stroke. Methods We performed a randomized controlled double blind trial (RCT). Adults (30–80 years old) who had a stroke 3 months to 5 years ago, were randomly assigned to either an intervention group (n = 38), an active control group (i.e., mock training; n = 35), or a waiting list control group (n = 24). The intervention and mock training consisted of 58 half-hour sessions within 12 weeks. The primary subjective outcome measures were cognitive functioning (Cognitive Failure Questionnaire), executive functioning (Dysexecutive Functioning Questionnaire), quality of life (Short Form Health Survey), instrumental activities of daily living (IADL; Lawton & Brody IADL scale), and participation in society (Utrecht Scale for Evaluation of Rehabilitation-Participation). Secondary subjective outcome measures were recovery after stroke, depressive symptoms (Hospital Anxiety Depression Scale—depression subscale), fatigue (Checklist Individual Strength—Fatigue subscale), and subjective cognitive improvement (exit list). Finally, a proxy of the participant rated the training effects in subjective cognitive functioning, subjective executive functioning, and IADL. Results and conclusions All groups improved on the two measures of subjective cognitive functioning and subjective executive functioning, but not on the other measures. These cognitive and executive improvements remained stable 4 weeks after training completion. However, the intervention group did not improve more than the two control groups. This suggests that improvement was due to training-unspecific effects. The proxies did not report any improvements. We, therefore, conclude that the computer-based cognitive flexibility training did not improve subjective cognitive functioning or quality of life after stroke.

Can a prediction model combining self-reported symptoms, sociodemographic and clinical features serve as a reliable first screening method for sleep apnea syndrome in patients with stroke?

OBJECTIVE To determine whether a prediction model combining self-reported symptoms, sociodemographic and clinical parameters could serve as a reliable first screening method in a step-by-step diagnostic approach to sleep apnea syndrome (SAS) in stroke rehabilitation. DESIGN Retrospective study. SETTING Rehabilitation center. PARTICIPANTS Consecutive sample of patients with stroke (N=620) admitted between May 2007 and July 2012. Of these, 533 patients underwent SAS screening. In total, 438 patients met the inclusion and exclusion criteria. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES We administered an SAS questionnaire consisting of self-reported symptoms and sociodemographic and clinical parameters. We performed nocturnal oximetry to determine the oxygen desaturation index (ODI). We classified patients with an ODI ≥15 as having a high likelihood of SAS. We built a prediction model using backward multivariate logistic regression and evaluated diagnostic accuracy using receiver operating characteristic analysis. We calculated sensitivity, specificity, and predictive values for different probability cutoffs. RESULTS Thirty-one percent of patients had a high likelihood of SAS. The prediction model consisted of the following variables: sex, age, body mass index, and self-reported apneas and falling asleep during daytime. The diagnostic accuracy was .76. Using a low probability cutoff (0.1), the model was very sensitive (95%) but not specific (21%). At a high cutoff (0.6), the specificity increased to 97%, but the sensitivity dropped to 24%. A cutoff of 0.3 yielded almost equal sensitivity and specificity of 72% and 69%, respectively. Depending on the cutoff, positive predictive values ranged from 35% to 75%. CONCLUSIONS The prediction model shows acceptable diagnostic accuracy for a high likelihood of SAS. Therefore, we conclude that the prediction model can serve as a reasonable first screening method in a stepped diagnostic approach to SAS in stroke rehabilitation.