Daytime sleepiness and its relationships to fatigue and autonomic dysfunction in adults with spinal cord injury

Autonomic Cardiovascular Control, Psychological Well-Being, and Cognitive Performance in People With Spinal Cord Injury

PURPOSE

To examine associations between parameters of psychological well-being, injury characteristics, cardiovascular autonomic nervous system (ANS) control, and cognitive performance in persons with spinal cord injury (SCI) compared with age-matched uninjured controls. This is an observational, cross-sectional study including a total of 94 participants (52 with SCI and 42 uninjured controls: UIC). Cardiovascular ANS responses were continuously monitored at rest and during administration of the Paced Auditory Serial Addition Test (PASAT). Self-report scores on the SCI-Quality of Life questionnaires are reported for depression, anxiety, fatigue, resilience, and positive affect. Participants with SCI performed significantly more poorly on the PASAT compared with the uninjured controls. Although not statistically significant, participants with SCI tended to report more psychological distress and less well-being than the uninjured controls. In addition, when compared with uninjured controls, the cardiovascular ANS responses to testing were significantly altered in participants with SCI; however, these responses to testing did not predict PASAT performance. Self-reported levels of anxiety were significantly related to PASAT score in the SCI group, but there was no significant relationship between PASAT and the other indices of SCI-Quality of Life. Future investigations should more closely examine the relationship among cardiovascular ANS impairments, psychological disorders, and cognitive dysfunction to better elucidate the underpinnings of these deficits and to guide interventions aimed at improving physiological, psychological, and cognitive health after SCI. Tetraplegia, paraplegia, blood pressure variability, cognitive, mood.

Pulse rate variability: An alternative to heart rate variability in adults with spinal cord injury

Pulse rate variability (PRV) is often used as an alternative to heart rate variability (HRV) to measure psychophysiological function. However, its validity to do so is unclear, especially in adults with spinal cord injury (SCI). This study compared PRV and HRV in adults with higher-level SCI (SCI-H, n = 23), lower-level SCI (SCI-L, n = 22), and able-bodied participants (AB n = 44), in a seated position as a function of performance in a reactivity task (Oxford Sleep Resistance Test: OSLER). PRV and HRV was measured using reflective finger-based photoplethysmography (PPG) and electrocardiography, respectively, at baseline, immediately post-OSLER, and after five-minute recovery. Agreement between PRV and HRV was determined by Bland-Altman analysis and differences between PRV and HRV over time by linear mixed effects model (LMM) analysis. Concurrent validity was assessed through correlation analyses between PRV and HRV. Additional correlation analyses were performed with psychosocial factors. Results indicated insufficient to moderate agreement between PRV and HRV. LMM analyses indicated no differences over time for standard deviation of normal-to-normal intervals and low-frequency power but significant differences for root mean square of successive differences and high frequency power. Nevertheless, PRV and HRV were highly correlated (Median r = .878 (.675-.990)) during all assessment periods suggesting sufficient concurrent validity. Similar correlation patterns were also found for PRV and HRV with psychosocial outcomes. While differences existed, results suggest PRV derived from reflective finger-based PPG is a valid proxy of HRV in tracking psychophysiological function in adults with SCI and could therefore be used as a more accessible monitoring tool.

Association between Daytime Sleepiness, Fatigue and Autonomic Responses during Head-Up Tilt Test in Multiple Sclerosis Patients

We aimed to assess dynamic changes in hemodynamic and autonomic function in response to the head-up tilt test (HUTT) in patients with multiple sclerosis (MS) compared to healthy controls (HCs) and evaluate its relationship with the patients' reported daytime sleepiness and fatigue symptoms. A total of 58 MS patients and 30 HCs were included in the analysis. Fatigue and sleepiness were evaluated using the Chalder Fatigue Scale (CFQ) and the Epworth Sleepiness Scale (ESS), respectively. Hemodynamic response, baroreflex sensitivity, heart rate variability, and systolic and diastolic blood pressure (BP) variability (SBPV, DBPV) parameters were calculated at rest, and in response to the HUTT. The MS patients displayed attenuated BP responses coupled with a more pronounced decrease in cardiac index as well as a reduced increase in the low frequency (LFnu) of DBPV (p = 0.021) and the sympathovagal ratio (p = 0.031) in the latter-phase orthostatic challenge compared to HCs. In MS patients, the ESS score showed no correlation with CFQ or clinical disease outcomes, but exhibited a moderate correlation with LFnu of BPVrest. Fatigue and disease variants predicted blood pressure response to HUTT. These findings underscore the importance of subjective daytime sleepiness and fatigue symptoms and their role in blood pressure regulation in MS patients.

The impact of sleep quality on health, participation and employment outcomes in people with spinal cord injury: Analyses from a large cross-sectional survey

BACKGROUND

Poor sleep is common in people with spinal cord injury (SCI), yet little is known about its impact on employment and participation outcomes.

OBJECTIVES

This study aimed to (1) describe the sleep quality of a large sample of Australians with SCI and compare the results to data from an adult control and other clinical populations; (2) examine associations between sleep quality and participant characteristics; and (3) explore the relationship between sleep and outcomes.

METHODS

Cross-sectional data from the Australian arm of the International Spinal Cord Injury (Aus-InSCI) survey from 1579 community-dwelling people aged >18 years with SCI were analysed. Sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI). Relationships between participant characteristics, sleep quality and other outcomes were examined with linear and logistic regression.

RESULTS

The PSQI was completed by 1172 individuals; 68% reported poor sleep (global PSQI score >5). Subjective sleep quality in people with SCI was poor (mean PSQI = 8.5, SD 4.5) when compared to adults without SCI (PSQI = 5.00, SD 3.37) and with traumatic brain injury (PSQI = 5.54, SD 3.94). Financial hardship and problems with secondary health conditions were significantly associated with worse sleep quality (p < 0.05). Poor sleep quality was strongly associated with lower emotional wellbeing and energy, and greater problems with participation (p < 0.001). Individuals engaged in paid work reported better sleep quality (mean PSQI = 8.1, SD 4.3) than unemployed individuals (mean PSQI = 8.7, SD 4.6; p < 0.05). Following adjustment for age, pre-injury employment, injury severity and years of education, better sleep quality remained strongly associated with being employed (OR 0.95, 95% CI 0.92 to 0.98; p = 0.003).

CONCLUSIONS

This study demonstrated pervasive and impactful relationships between sleep quality and important SCI outcomes. Poor sleep quality was strongly associated with worse emotional wellbeing and vitality, unemployment and lower participation. Future studies should aim to determine whether treating sleep problems can improve outcomes for people living with SCI.

Factors Associated With Fatigue in People With Spinal Cord Injury: A Systematic Review and Meta-analysis

OBJECTIVE

To investigate the association between fatigue and clinical and demographic variables in people with spinal cord injury (SCI).

DATA SOURCES

Five databases (MEDLINE, Physiotherapy Evidence Database, Cochrane, Google Scholar, Cumulative Index to Nursing and Allied Health) were searched up to November 2021.

STUDY SELECTION

Observational studies that reported the association between fatigue and clinical and demographic variables in English or Spanish were eligible. Reviews, qualitative research studies, and nonoriginal articles were excluded. Twenty-three of the 782 identified studies met the inclusion criteria for the meta-analysis.

DATA EXTRACTION

Two researchers independently extracted the data. The strength of the association between each factor and fatigue was determined by the effect size. When the results of the effect size were expressed with different statistics, the correlation coefficient was the preferred estimation. The risk of bias was assessed using the Appraisal Tool for Cross-Sectional Studies and the Newcastle-Ottawa Scale.

DATA SUMMARY

A pooled analysis of the associations between fatigue and 17 factors was performed. A direct association was found between fatigue and 9 factors (sorted by effect size): anxiety (r=0.57; 95% CI, 0.29-0.75), stress (r=0.54; 95% confidence interval [CI], 0.26-0.74), depression (r=0.47; 95% CI, 0.44-0.50), pain (r=0.34; 95% CI, 0.16-0.50), analgesic medication (r=0.32; 95% CI, 0.28-0.36), assistive devices (r=0.23; 95% CI, 0.17-0.29), lesion level (r=0.15; 95% CI, 0.07-0.23), incomplete SCI (r=0.13; 95% CI, 0.05-0.22), and medication (r=0.12; 95% CI, 0.01-0.23). An inverse association was found with 3 factors (sorted by effect size): self-efficacy (r=-0.63; 95% CI, -0.81 to -0.35), participation (r=-0.32; 95% CI, -0.58 to -0.001), and physical activity (r=-0.17; 95% CI, -0.28 to -0.05). No association was found with age, sex, educational level, time since injury, and spasticity.

CONCLUSIONS

Several factors were associated with fatigue in people with SCI, with those related to mental health showing the strongest associations. These results should be interpreted with caution because of the high heterogeneity observed in some factors.

The role of arousal and motivation in emotional conflict resolution: Implications for spinal cord injury

Under many conditions, emotional information is processed with priority and it may lead to cognitive conflict when it competes with task-relevant information. Accordingly, being able to ignore emotional information relies on cognitive control. The present perspective offers an integrative account of the mechanism that may underlie emotional conflict resolution in tasks involving response activation. We point to the contribution of emotional arousal and primed approach or avoidance motivation in accounting for emotional conflict resolution. We discuss the role of arousal in individuals with impairments in visceral pathways to the brain due to spinal cord lesions, as it may offer important insights into the “typical” mechanisms of emotional conflict control. We argue that a better understanding of emotional conflict control could be critical for adaptive and flexible behavior and has potential implications for the selection of appropriate therapeutic interventions.

Altered heart rate variability and pulse-wave velocity after spinal cord injury

BACKGROUND

Heart rate variability (HRV) and pulse-wave velocity (PWV), indicators of cardiac function, are altered in patients with spinal cord injury (SCI), suggesting that autonomic cardiac function and arterial stiffness may underlie the high risk of cardiovascular complications in these patients. No study has simultaneously investigated HRV and PWV in the same patients.

AIM

To evaluate cardiovascular complications in SCI patients by comparing HRV and PWV between patients with and without SCI.

METHODS

In this cross-sectional pilot study, patients with (n = 60) and without SCI (n = 60) were recruited from December 7, 2019 to January 21, 2020. Each participant received a five-minute assessment of HRV and the cardiovascular system using the Medicore HRV Analyzer SA-3000P. Differences in HRV and PWV parameters between participants with and without SCI were statistically examined.

RESULTS

We observed a significant difference between participants with and without SCI with respect to the standard deviation of all normal-to-normal intervals, square root of the mean sum of squared successive risk ratio interval differences, physical stress index, total power, very-low frequency, low frequency, high frequency, and arterial elasticity.

CONCLUSION

Patients with SCI have weaker sympathetic and parasympathetic activity as well as lower arterial elasticity compared to those without, suggesting that SCI may increase cardiac function loading.

Investigating Dynamics of the Spinal Cord Injury Adjustment Model: Mediation Model Analysis

Spinal cord injury (SCI) is a severe neurological injury that results in damage to multiple bodily systems. SCI rehabilitation requires a significant focus on improving adjustment to the injury. This paper presents a detailed description of the Spinal Cord Injury Adjustment Model (SCIAM), which clarifies how individuals adjust to SCI and contends that adjustment to SCI is a multifactorial process involving non-linear dynamic adaptation over time. Evidence supporting SCIAM is also discussed. Mediation analyses were conducted to test the mediator dynamics proposed by the model. The analyses tested the relationship between two moderators (self-care and secondary health conditions), mediators (two self-efficacy items and appraisal of quality of life or QoL), and positive versus negative vitality/mental health as outcomes. Results showed that higher self-efficacy and perceived QoL was related to greater independence in self-care and reduced negative impacts of secondary health conditions. This study supported the mediation role of self-efficacy and other appraisals such as perceived QoL in enhancing self-care and buffering the negative impact of health challenges. In conclusion, it is important to employ a holistic model such as SCIAM to conceptualise and increase understanding of the process of adjustment following a severe neurological injury such as SCI.

Psychophysiological impact of spinal cord injury: Depression, coping and heart rate variability

OBJECTIVES

The aim was to examine the association of post-injury heart rate variability (HRV), coping with injury (fighting-acceptance), and depression symptoms in individuals with spinal cord injury (SCI).

STUDY DESIGN

Cross-sectional study.

SETTING

Tertiary care spinal cord injury hospital.

PARTICIPANTS

Ninety-one individuals with SCI.

METHODS

All participants were assessed for HRV using polar heart rate monitor RS 800 CX and completed the Patient Health Questionnaire and Spinal Cord Lesion Coping Strategy questionnaire. Participants were grouped based on level of injury (tetraplegic, high paraplegia, and low paraplegia) and injury duration (early vs. late). Odds ratio calculated the risk of depression using HRV and coping as factors for early and late duration groups. Spearman rho estimated the correlation between three ratios: HRV (LF vs. HF), depression (somatic vs. cognitive), and coping (fighting spirit vs. acceptance) for each level of injury group for early and late duration.

RESULTS

Individuals with SCI with high HRV had lower odds of depression (OR = 0.14, CI = 0.03-0.78) than individuals with SCI with low HRV in the early duration group. Individuals with SCI with high acceptance had lower odds of depression (OR = 0.19, CI  = 0.44-0.79) than individuals with SCI with low acceptance in the later duration group. In the later duration, HRV ratio negatively correlated with coping ratio in individuals with low paraplegia and depression ratio in individuals with high paraplegia.

CONCLUSION

The aftermath of spinal cord injury might reflect a close association between the physiological response of autonomic variability and psychological response of coping and depression with implications for the level of injury and post-injury duration.

A neuro-cardiac self-regulation therapy to improve autonomic and neural function after SCI: a randomized controlled trial protocol

BACKGROUND

Spinal cord injury (SCI) is associated with autonomic imbalance and significant secondary conditions, including cardiac and brain dysfunction that adversely impact health and wellbeing. This study will investigate the effectiveness (intention-to-treat) of a neuro-cardiac self-regulation therapy to improve autonomic and neural/brain activity in adults with SCI living in the community.

METHODS

A two-arm parallel, randomised controlled trial in which adults with SCI living in the community post-rehabilitation will be randomly assigned to a treatment or control group. The treatment group (N = 60) aged 18-70 years with a chronic traumatic or non-traumatic SCI, will receive intervention sessions once per week for 10 weeks, designed to regulate autonomic activity using computer-based feedback of heart rate variability and controlled breathing (called HRV-F). Comprehensive neurophysiological and psychological assessment will occur at baseline, immediate post-treatment, and 6 and 12-months post-treatment. Primary outcome measures include electrocardiography/heart rate variability (to assess autonomic nervous system function) and transcranial doppler sonography (to assess cerebral blood circulation in basal cerebral arteries). Secondary outcomes measures include continuous blood pressure, electroencephalography, functional near-infrared spectroscopy, respiration/breath rate, electrooculography, cognitive capacity, psychological status, pain, fatigue, sleep and quality of life. Controls (N = 60) will receive usual community care, reading material and a brief telephone call once per week for 10 weeks and be similarly assessed over the same time period as the HRV-F group. Linear mixed model analysis with repeated measures will determine effectiveness of HRV-F and latent class mixture modelling used to determine trajectories for primary and selected secondary outcomes of interest.

DISCUSSION

Treatments for improving autonomic function after SCI are limited. It is therefore important to establish whether a neuro-cardiac self-regulation therapy can result in improved autonomic functioning post-SCI, as well as whether HRV-F is associated with better outcomes for secondary conditions such as cardiovascular health, cognitive capacity and mental health.

TRIAL REGISTRATION

The study has been prospectively registered with the Australian and New Zealand Clinical Trial Registry ( ACTRN12621000870853 .aspx). Date of Registration: 6th July 2021. Trial Sponsor: The University of Sydney, NSW 2006. Protocol version: 22/07/2021.

Evidence on definitions, concepts, outcome instruments, and interventions for chronic fatigue in spinal cord injury: a scoping review protocol

OBJECTIVE

The objective of this review is to review the existing evidence on definitions, concepts, measurement instruments, and interventions for chronic fatigue in spinal cord injury.

INTRODUCTION

Chronic fatigue in people with spinal cord injury is an under-studied issue that affects between 25% and 56.6% of people with spinal cord injury. There are questions about how it is defined and managed due to its complex, multifactorial nature and relationship with related conditions. No overview of chronic fatigue in spinal cord injury exists and we are in need of a shared definition of chronic fatigue, as well as a comprehensive review of concepts and evidence supporting outcome instruments and interventions.

INCLUSION CRITERIA

This review will include empirical and non-empirical studies that focus on definitions, concepts, measurement instruments, and interventions for chronic fatigue in spinal cord injury. Studies that focus on peripheral muscle fatigue will only be included if they include chronic fatigue as a secondary outcome.

METHODS

This review will be done in three phases. Phase I will provide an overview of definitions of chronic fatigue in spinal cord injury and will include a qualitative analysis of concept attributes and characteristics. Phase II will focus on factors related to chronic fatigue and measurement instruments used to measure chronic fatigue, and phase III will focus on interventions. Full texts will be screened by two independent reviewers against inclusion criteria. Results will be presented in tabular form with a narrative summary.

Excessive daytime sleepiness in adults with spinal cord injury and associations with pain catastrophizing and pain intensity

STUDY DESIGN

Pre-post cohort mixed factorial design.

OBJECTIVE

Excessive daytime sleepiness (EDS) and chronic pain are major problems for people with spinal cord injury (SCI). However, the relationship between chronic pain and EDS requires clarification. The goal of the study was to determine associations between pain catastrophizing (PC) and pain intensity (PI) with EDS in adults with SCI.

SETTING

New South Wales, Australia.

METHODS

Participants included 45 adults with SCI and 44 able-bodied controls. The relationship between PI, PC, and EDS was explored by determining the influence of PC and PI on the performance of both groups in a behavioral test of EDS called the Oxford Sleep Resistance Test. PC and PI were assessed by self-report. The association between EDS, pain, and other relevant factors like fatigue and mood was established using multidimensional scaling in the SCI group data.

RESULTS

PC was found to have a significant association with EDS, with 33.3% falling asleep in the SCI group with low PC, compared with 70% in those with high PC. Only 10% of the controls fell asleep regardless of PC. PI did not significantly influence EDS in either group. Multidimensional scaling showed EDS was closely related to PC, PI, pain interference, fatigue, and mood.

CONCLUSIONS

PC appears to be strongly associated with EDS in SCI. Findings suggest significant sleep benefits may occur in adults with SCI by treating cognitive biases like PC, as well as addressing associated factors like fatigue, pain interference, low mood, and so on.