Sleep Disorders in Spinal Cord Injury

Cardiac autonomic nervous activity during different sleep stages in individuals with spinal cord injury: The influence of physical training

OBJECTIVE

The present study assessed the influence of physical training on cardiac autonomic activity in individuals with spinal cord injury (SCI) during different sleep stages.

METHODS

Twenty-six volunteers were allocated into three groups: 9 sedentary individuals without SCI (control, CON); 8 sedentary tetraplegic individuals with chronic SCI (SED-SCI); 9 physically trained tetraplegic individuals with chronic SCI (TR-SCI). All participants underwent nocturnal polysomnography to monitor sleep stages: wakefulness, non-rapid eye movement (NREM) sleep (N1, N2, and N3 stages), and REM sleep. The electrocardiography data obtained during this exam were extracted to analyze the heart rate variability (HRV).

RESULTS

Sleep stages influenced HRV in the time [RR interval and root mean square of successive RR interval differences (RMSSD)] and frequency [low-frequency (LF) and high-frequency (HF) powers and LF-to-HF ratio] domains (P < 0.05). SED-SCI individuals showed unchanged HRV compared to CON (P > 0.05). When comparing the TR-SCI and SED-SCI groups, no significant differences in HRV were reported in the time domain (P > 0.05). However, in the frequency domain, more accentuated HF power was observed in TR-SCI than in SED-SCI individuals during the N2 and N3 stages and REM sleep (P < 0.05). Moreover, TR-SCI had higher HF power than CON during the N3 stage (P < 0.05).

CONCLUSIONS

TR-SCI individuals have greater HF power, indicative of parasympathetic modulation, than sedentary (injured or not injured) individuals during different sleep stages. Therefore, enhanced parasympathetic activity induced by physical training may improve cardiac autonomic modulation during sleep in individuals with chronic SCI.

Relating Spinal Injury-Induced Neuropathic Pain and Spontaneous Afferent Activity to Sleep and Respiratory Dysfunction

Abstract Spinal cord injury (SCI) can induce dysfunction in a multitude of neural circuits including those that lead to impaired sleep, respiratory dysfunction, and neuropathic pain. We used a lower thoracic rodent contusion SCI model of neuropathic pain that has been shown to associate with increased spontaneous activity in primary afferents and hindlimb mechanosensory stimulus hypersensitivity. Here we paired capture of these variables with chronic capture of three state sleep and respiration to more broadly understand SCI-induced physiological dysfunction and to assess possible interrelations. Noncontact electric field sensors were embedded into home cages to non-invasively capture the temporal evolution of sleep and respiration changes for six weeks after SCI in naturally behaving mice. Hindlimb mechanosensitivity was assessed weekly, and terminal experiments measured primary afferent spontaneous activity in situ from intact lumbar dorsal root ganglia (DRG). We observed that SCI led to increased spontaneous primary afferent activity (both firing rate and the number of spontaneously active DRGs) that correlated with increased respiratory rate variability and measures of sleep fragmentation. This is the first study to measure and link sleep dysfunction and variability in respiratory rate in a SCI model of neuropathic pain, and thereby provide broader insight into the magnitude of overall stress burden initiated by neural circuit dysfunction after SCI.

Perceived sleep problems after spinal cord injury: Results from a community-based survey in Switzerland

Objective: To investigate the burden of sleep problems within the Spinal Cord injured (SCI) community with respect to the general population (GP) in Switzerland. The study further explored potential predictors for receiving treatment for sleep problems after SCI.Design: Cross-sectional study.Setting: SCI community in Switzerland.Participants: Individuals diagnosed with an SCI, aged 16 years or older that permanently reside in Switzerland (N = 1549).Interventions: Not applicable.Outcome measures: Perceived sleep problems within the SCI community and GP. For those with sleep problems and SCI, an indicator for having received treatment was measured.Results: 58.8% of survey participants indicated having a sleep problem; 69.4% of those with a sleep problem did not indicate receiving treatment. Amongst people living with an SCI, individuals between the ages of 46-60 years (adjusted Odds Ratio, OR = 3.07; 95% CI 1.54-6.16), participants reporting severe financial hardship (OR = 2.90; 95% CI) 1.69-4.96, and those that indicated having pain (OR = 5.62; 95% CI 3.52-8.98) were more likely to have a chronic sleep problem. In comparison to the Swiss GP, the prevalence of having a sleep problem was 18% higher among persons with SCI, with the largest discrepancy for males with paraplegia between the ages of 46-60 years (Prevalence ratio, PR = 1.28; 95% CI, 1.21-1.36).Conclusion: Individuals with SCI experience more sleep problems compared to the Swiss GP. Findings from this study suggest that clinical screening for sleep issues targeting high risk groups is needed to reduce the large prevalence of non-treatment in individuals with SCI.

Sleep quality in individuals with short-duration chronic spinal cord injury

The aim of the study is to estimate the association between spinal cord injuries related medical factors and subjective sleep disturbance in individuals with short-duration chronic spinal cord injury. Seventy-nine individuals with traumatic spinal cord injuries were included in our study and evaluated using the Beck Depression Index for severity of depressive symptoms, Short-Form Health Survey for quality of life, Douleur Neuropathique 4 score for neuropathic pain severity, and the Pittsburgh Sleep Quality Index for subjective sleep disturbances in a tertiary rehabilitation center. Associated subjective sleep disturbance factors were predicted using multivariate binary logistic regression analysis. Subjective sleep disturbance frequency was 74.7 %, and significantly higher in individuals with paraplegia (P = 0.025, odds ratio, 9.74, 95% confidence interval, 1.21-78.14). Intermittent nighttime catheterization frequency and neuropathic pain severity levels were significantly higher in individuals with subjective sleep disturbance, and quality of life and depressive symptoms were significantly worse in individuals with subjective sleep disturbance. Poor-sleep quality was associated significantly with shorter spinal cord injury duration. The strongest associated factors for sleep disturbance were paraplegic involvement, severity of depressive symptoms (Beck Depression Index score), and quality of life (Short-Form Health Survey general health perceptions score) (odds ratio: 95% confidence interval, 29.75; 1.66-534.36, 1.47; 1.11-1.95, and 0.91; 0.85-0.97, respectively). Our study suggests that paraplegic involvement, low quality of life, and depressive mood are related to sleep disturbance in individuals with traumatic spinal cord injury.

Respiratory problems and management in people with spinal cord injury

Spinal cord injury (SCI) is characterised by profound respiratory compromise secondary to the level of loss of motor, sensory and autonomic control associated with the injury. This review aims to detail these anatomical and physiological changes after SCI, and outline their impact on respiratory function. Injury-related impairments in strength substantially alter pulmonary mechanics, which in turn affect respiratory management and care. Options for treatments must therefore be considered in light of these limitations.

KEY POINTS

Respiratory impairment following spinal cord injury (SCI) is more severe in high cervical injuries, and is characterised by low lung volumes and a weak cough secondary to respiratory muscle weakness.Autonomic dysfunction and early-onset sleep disordered breathing compound this respiratory compromise.The mainstays of management following acute high cervical SCI are tracheostomy and ventilation, with noninvasive ventilation and assisted coughing techniques being important in lower cervical and thoracic level injuries.Prompt investigation to ascertain the extent of the SCI and associated injuries, and appropriate subsequent management are important to improve outcomes.

EDUCATIONAL AIMS

To describe the anatomical and physiological changes after SCI and their impact on respiratory function.To describe the changes in respiratory mechanics seen in cervical SCI and how these changes affect treatments.To discuss the relationship between injury level and respiratory compromise following SCI, and describe those at increased risk of respiratory complications.To present the current treatment options available and their supporting evidence.