Sleep apnea syndrome in chronic spinal cord injury: associated factors and treatment

Melatonin secretion and sleep disorders in patients with spinal cord injuries

STUDY DESIGN

Prospective observational study.

OBJECTIVES

To evaluate melatonin secretion, daytime sleepiness and sleep disorders in patients with spinal cord injuries (SCI), and their association with lesion level.

SETTING

Specialized neuro rehabilitation hospital in France METHODS: Prospective observational study of patients aged over 18 hospitalized in for spinal cord injury. Sleep quality was measured with the Pittsburgh Sleep Quality Index (PQSI), daytime sleepiness with the Epworth Sleepiness scale (ESS), and melatonin secretion by 24 h urinary dosage of 6-sulphatoxy-melatonin.

RESULTS

213 patients were screened, 21 patients were included: 17 complete (AIS A) and 4 lesions (AIS B), 76% of traumatic origin with 12 tetraplegic and 9 paraplegic, mean 10 (range 0.5-40) years after injury. Mean age was 46.8 ± 14.7 years, mean BMI 23.56 ± 4.1 and men outnumbered women (15 vs 6). Melatonin secretion was analyzed by 24 h secretion and by secretion profile. Comparing retained vs abolished secretion, only 23% (4/17) of patients with a lesion above T8 retained melatonin secretion, compared to 80% (4/5) with a lesion below T8 (p = 0.022). Non significant differences were found in secretion profile in patients who retained secretion: no patient with a lesion above T8 had a normal secretion profile compared to 50% with a lesion below T8 and in the impact of partial vs total lesions above T8 in whom 17% (2/12) of complete ASIA-A lesions and 50% (2/4) of incomplete lesions retained secretion.

CONCLUSION

Lesions of the spinal cord above T8 are strongly associated with abolition of melatonin secretion.

Primary Care in the Spinal Cord Injury Population: Things to Consider in the Ongoing Discussion

Purpose of Review

Spinal cord injury (SCI) creates unique needs that if not recognized and addressed timely can have detrimental effects on the health and quality of life (QOL) of people living with a SCI. Primary preventive health care is shown to decrease morbidity and mortality, yet the SCI population reportedly faces challenges getting access to this care. This area in SCI health care is still largely understudied with no consensus on the ideal way or which health care provider is best to provide primary care for this population.

Findings

Preventive care is generally provided by general primary care providers, but not all primary care providers are trained in recognizing and addressing spinal cord injury-specific needs. SCI providers generally are not trained in addressing all aspects of preventive care. Knowing the recommended preventive care screenings, recognizing and managing specific conditions seen after a SCI, and seamless coordination of care between general practitioners and SCI specialists are some of the interventions to help prevent health complications, decrease morbidity and mortality, improve health outcomes, and promote QOL in this patient population.

Summary

Prioritized focus on preventive care is necessary for a positive impact on the overall health and QOL in this population. Addressing the knowledge gap reported by primary care providers and SCI providers may help increase the probability of SCI patients getting their preventive and specialty care needs addressed. We present a "cheat sheet" of recommendations for the preventive care evaluation of a person living with a SCI.

Tetraplegic obstructive sleep apnoea patients dilate the airway similarly to able-bodied obstructive sleep apnoea patients

Context/objective: Obstructive sleep apnoea (OSA) develops soon after cervical spinal cord injury (SCI) at rates higher than the general population, but the mechanisms are not understood. This study aimed to determine whether OSA in SCI is associated with altered pharyngeal muscle dilatory mechanics during quiet breathing, as has been observed in the non-SCI injured with obstructive sleep apnoea.Design: Cross sectional imaging study.Setting: Medical research institute.Participants: Eight cervical SCI patients with OSA were recruited and compared to 13 able-bodied OSA patients and 12 able-bodied healthy controls of similar age and BMI.Interventions and outcome measures: 3T MRI scans of upper airway anatomy and tagged-MRI to characterize airway muscle motion during quiet breathing were collected for analysis.Results: Considerable variation in the patterns of inspiratory airway muscle motion was observed in the SCI group, with some participants exhibiting large inspiratory airway dilatory motions, and others exhibiting counterproductive narrowing during inspiration. These patterns were not dissimilar to those observed in the able-bodied OSA participants. The increase in airway cross-sectional area of able-bodied control participants was proportional to increase in BMI, and a similar, but not significant, relationship was present in all groups.Conclusion: Despite the limited sample size, these data suggest that SCI OSA patients have heterogeneous pharyngeal dilator muscle responses to the negative pressures occurring during inspiration but, as a group, appear to be more similar to able-bodied OSA patients than healthy controls of similar age and BMI. This may reflect altered pharyngeal pressure reflex responses in at least some people with SCI.

Sleep apnea and unilateral upper and lower extremity allodynia as a result of a large thoracic disc herniation: a case report

Background

Clinically significant disc herniations in the thoracic spine are rare accounting for approximately 1% of all disc herniations. In patients with significant spinal cord compression, presenting symptoms typically include ambulatory dysfunction, lower extremity weakness, lower extremity sensory changes, as well as bowl, bladder, or sexual dysfunction. Thoracic disc herniations can also present with thoracic radiculopathy including midback pain and radiating pain wrapping around the chest or abdomen. The association between thoracic disc herniation with cord compression and sleep apnea is not well described.

Case presentation

The following is a case of a young male patient with high grade spinal cord compression at T7-8, as a result of a large thoracic disc herniation. The patient presented with complaints of upper and lower extremity unilateral allodynia and sleep apnea. Diagnosis was only made once the patient manifested more common symptoms of thoracic stenosis including left lower extremity weakness and sexual dysfunction. Following decompression and fusion the patient’s allodynia and sleep apnea quickly resolved.

Conclusions

Thoracic disc herniations can present atypically with sleep apnea. We recommend taking into consideration that sleep symptoms may resolve when planning treatment for thoracic disc herniation.

Detection of Sleep-Disordered Breathing in Patients with Spinal Cord Injury Using a Smartphone

Patients with spinal cord injury (SCI) have an increased risk of sleep-disordered breathing (SDB), which can lead to serious comorbidities and impact patients’ recovery and quality of life. However, sleep tests are rarely performed on SCI patients, given their multiple health needs and the cost and complexity of diagnostic equipment. The objective of this study was to use a novel smartphone system as a simple non-invasive tool to monitor SDB in SCI patients. We recorded pulse oximetry, acoustic, and accelerometer data using a smartphone during overnight tests in 19 SCI patients and 19 able-bodied controls. Then, we analyzed these signals with automatic algorithms to detect desaturation, apnea, and hypopnea events and monitor sleep position. The apnea–hypopnea index (AHI) was significantly higher in SCI patients than controls (25 ± 15 vs. 9 ± 7, p < 0.001). We found that 63% of SCI patients had moderate-to-severe SDB (AHI ≥ 15) in contrast to 21% of control subjects. Most SCI patients slept predominantly in supine position, but an increased occurrence of events in supine position was only observed for eight patients. This study highlights the problem of SDB in SCI and provides simple cost-effective sleep monitoring tools to facilitate the detection, understanding, and management of SDB in SCI patients.

Relationship Between Sleep-Disordered Breathing and Neurogenic Obesity in Adults With Spinal Cord Injury

Spinal cord injury (SCI) substantially increases the risk of neurogenic obesity, diabetes, and metabolic syndrome. Much like in the general population, a discussion of these syndromes in SCI would be incomplete without acknowledging the association of SCI with sleep-disordered breathing (SDB). This article will outline the interplay between obesity and obstructive sleep apnea (OSA), discussing the pathophysiology of obesity in OSA both for the general population and SCI population. The role of insulin resistance in SDB and SCI will also be examined. The epidemiology and pathophysiology of OSA and central sleep apnea in SCI are discussed through an examination of current evidence, followed by a review of central sleep apnea in SCI. Principles of diagnosis and management of SDB will also be discussed. Because sleep deprivation in itself can be a risk factor for developing obesity, the significance of comorbid insomnia in SCI is explored. Ultimately, a thorough sleep history, testing, and treatment are key to improving the sleep of individuals with SCI and to potentially reducing the impact of neurogenic obesity and metabolic syndrome.

Prevalence of sleep-disordered breathing in people with tetraplegia-a systematic review and meta-analysis

STUDY DESIGN

Systematic review with meta-analysis.

OBJECTIVES

To determine the prevalence of sleep-disordered breathing (SDB) in people with tetraplegia and to identify the characteristics associated with SDB.

METHODS

A systematic literature search using Medline, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL) and grey literature sources was conducted using a combination of spinal cord injury (SCI) and SDB related terms. Articles were restricted to publication dates between 1/1/2000 and 4/9/2020 and with objectively measured SDB with an overnight sleep study. The frequency of SDB stratified by the apnoea hypopnea index (AHI) was extracted and weighted averages, using a random effects model, were calculated with 95% confidence intervals. Sub-group analyses were performed where possible.

RESULTS

Twelve articles were included in the review; of these nine were included in meta-analysis (combined sample = 630). Sample sizes and case detection methods varied. Reported SDB prevalence rates ranged from 46 to 97%. The prevalence of at least mild (AHI ≥ 5), moderate (AHI ≥ 15) and severe (AHI ≥ 30) SDB were 83% (95% CI = 73-91), 59% (46-71) and 36% (26-46), respectively. Sub-group analyses found that prevalence increased with age (p < 0.001). There were no statistically significant differences in SDB prevalence by sex (p = 0.06), complete/incomplete SCI (p = 0.06), body mass index (p = 0.07), acute/chronic SCI (p = 0.73) or high/low level of cervical SCI (p = 0.90).

CONCLUSION

Our results confirm that SDB is highly prevalent in people with tetraplegia, and prevalence increases with age. The high prevalence suggests that routine screening and subsequent treatment should be considered in both acute and community care.

A review of sleep research in patients with spinal cord injury

Study design: Systematic review. Objectives: Sleep disturbances are a common complaint among individuals with spinal cord injury (SCI) and were not usually present before the SCI. Their sleep disturbances, including disrupted sleep, spasms, and problems with initiating and sustaining sleep through the night, affect SCI individuals' overall quality of life due to excessive tiredness and low energy levels during the day. Despite the high prevalence of sleep complaints in this population, current knowledge about sleep in the SCI population has not been systematically assessed. Setting: Capital Region of Denmark. Methods: We systematically reviewed literature identified from the PubMed and EMBASE databases following PRISMA guidelines.Thirty-seven articles met our inclusion criteria, as only controlled studies were included. This could be a comparison of (1) SCI individuals and able-bodied controls, (2) cervical with thoracolumbar SCI individuals, or (3) cervical, thoracolumbar SCI individuals and able-bodied controls. Results: Individuals with SCI have a higher prevalence of sleep-disordered breathing and periodic leg movements during sleep (PLMS), lower heart rate, but no nocturnal lowering of blood pressure. 24-hour energy expenditure and sleeping metabolic rate were significantly lower, and bowel movements were altered. Endocrine alterations were found in investigations of melatonin, cortisol and antidiuretic hormone. Questionnaires revealed a high prevalence of subjectively poorer sleep quality in individuals with SCI compared with able-bodied controls. Conclusions: There are significant differences between groups with SCI and able-bodied controls. SCI objectively and subjectively markedly affects an individual's sleep.

A Primary Care Provider's Guide to Managing Respiratory Health in Subacute and Chronic Spinal Cord Injury

Respiratory complications following spinal cord injury (SCI) have remained the leading cause of death across the lifespan and are one of the most common reasons for hospitalization. Complications from altered respiratory physiology after SCI include atelectasis, pneumonia, venous thromboembolic disease, and sleep-disordered breathing. The risk for complications is greater with higher SCI levels and severity, and mortality from pneumonia is heightened compared to the general population. Optimal primary care for individuals with SCI includes appropriate surveillance for SCI-specific respiratory disease, key preventive care including promotion of influenza immunization and respiratory muscle training, and early identification and treatment of pneumonia with institution of aggressive secretion management strategies. The respiratory physiology and specific management of respiratory complications after SCI is reviewed.

Acute intermittent hypoxia as a potential adjuvant to improve walking following spinal cord injury: evidence, challenges, and future directions

Purpose of Review

The reacquisition and preservation of walking ability are highly valued goals in spinal cord injury (SCI) rehabilitation. Recurrent episodes of breathing low oxygen (i.e., acute intermittent hypoxia, AIH) is a potential therapy to promote walking recovery after incomplete SCI via endogenous mechanisms of neuroplasticity. Here, we report on the progress of AIH, alone or paired with other treatments, on walking recovery in persons with incomplete SCI. We evaluate the evidence of AIH as a therapy ready for clinical and home use and the real and perceived challenges that may interfere with this possibility.

Recent Findings

Repetitive AIH is a safe and an efficacious treatment to enhance strength, walking speed and endurance, as well as, dynamic balance in persons with chronic, incomplete SCI.

Summary

The potential for AIH as a treatment for SCI remains high, but further research is necessary to understand treatment targets and effectiveness in a large cohort of persons with SCI.

Sleep-disordered breathing is associated with brain vascular reactivity in spinal cord injury

OBJECTIVE

To determine the population-level odds of individuals with spinal cord injury (SCI) experiencing fatigue and sleep apnea, to elucidate relationships with level and severity of injury, and to examine associations with abnormal cerebrovascular responsiveness.

METHODS

We used population-level data, meta-analyses, and primary physiologic assessments to provide a large-scale integrated assessment of sleep-related complications after SCI. Population-level and meta-analyses included more than 60,000 able-bodied individuals and more than 1,800 individuals with SCI. Physiologic assessments were completed on a homogenous sample of individuals with cervical SCI and matched controls. We examined the prevalence of (1) self-reported chronic fatigue, (2) clinically identified sleep apnea, and 3) cerebrovascular responsiveness to changing CO₂.

RESULTS

Logistic regression revealed a 7-fold elevated odds of chronic fatigue after SCI (odds ratio [OR] 7.9, 95% confidence interval [CI] 3.5-16.2), and that fatigue and trouble sleeping are correlated with the level and severity of injury. We further show that those with SCI experience elevated risk of clinically defined sleep-disordered breathing in more than 600 individuals with SCI (pooled OR 3.1, 95% CI 1.3-7.5). We confirmed that individuals with SCI experience a high rate of clinically defined sleep apnea using primary polysomnography assessments. We then provide evidence using syndromic analysis that sleep-disordered breathing is a factor strongly associated with impaired cerebrovascular responsiveness to CO₂ in patients with SCI.

CONCLUSIONS

Individuals with SCI have an increased prevalence of sleep-disordered breathing, which may partially underpin their increased risk of stroke. There is thus a need to integrate sleep-related breathing examinations into routine care for individuals with SCI.

Factors influencing adherence to continuous positive airway pressure devices in individuals with spinal cord injury and sleep apnea: Results of a qualitative study

BACKGROUND

In individuals with spinal cord injury (SCI) and sleep apnea (SA), adherence to continuous positive airway pressure (CPAP) therapy seems unsatisfactory despite technical and educational support implemented when starting treatment.

OBJECTIVE

We aimed to design comprehensive model of adherence to CPAP therapy in individuals with SCI and SA.

METHODS

This was a prospective qualitative study based on semi-directed interviews and using the grounded theory as an analytic method. The theoretical framework was the social cognitive theory of Bandura. Participants were recruited from an SCI referral centre. Individuals with SCI using or having used a CPAP device for SA were included. Data were collected by semi-directed interviews on the experience of individuals with SCI regarding SA and being fitted with a CPAP device and were coded and organized into categories of experience and category relationships.

RESULTS

Among the 17 individuals included; 9 had tetraplegia; the median age was 62 (Q1-Q3 47-66) years and median time since injury was 16 (Q1-Q3 1.75-21) years. Four categories of data were identified: 1) from symptoms to validation of SA diagnosis, 2) CPAP device fitting process, 3) representations of SA, and 4) level of adherence to the treatment. In addition to the factors already observed in the general population, the proposed model identified specific adherence factors in individuals with SCI, such as physical and relational dependence on a third party, increased daily care burden and increased presence of medical devices in the daily environment.

CONCLUSION

SA and its management present certain specificities in individuals with SCI that the physician must take into account to optimize therapeutic proposals, follow-up modalities and device adherence.

Positive airway pressure for sleep-disordered breathing in acute quadriplegia: a randomised controlled trial

RATIONALE

Highly prevalent and severe sleep-disordered breathing caused by acute cervical spinal cord injury (quadriplegia) is associated with neurocognitive dysfunction and sleepiness and is likely to impair rehabilitation.

OBJECTIVE

To determine whether 3 months of autotitrating CPAP would improve neurocognitive function, sleepiness, quality of life, anxiety and depression more than usual care in acute quadriplegia.

METHODS AND MEASUREMENTS

Multinational, randomised controlled trial (11 centres) from July 2009 to October 2015. The primary outcome was neurocognitive (attention and information processing as measure with the Paced Auditory Serial Addition Task). Daytime sleepiness (Karolinska Sleepiness Scale) was a priori identified as the most important secondary outcome.

MAIN RESULTS

1810 incident cases were screened. 332 underwent full, portable polysomnography, 273 of whom had an apnoea hypopnoea index greater than 10. 160 tolerated at least 4 hours of CPAP during a 3-day run-in and were randomised. 149 participants (134 men, age 46±34 years, 81±57 days postinjury) completed the trial. CPAP use averaged 2.9±2.3 hours per night with 21% fully 'adherent' (at least 4 hours use on 5 days per week). Intention-to-treat analyses revealed no significant differences between groups in the Paced Auditory Serial Addition Task (mean improvement of 2.28, 95% CI -7.09 to 11.6; p=0.63). Controlling for premorbid intelligence, age and obstructive sleep apnoea severity (group effect -1.15, 95% CI -10 to 7.7) did not alter this finding. Sleepiness was significantly improved by CPAP on intention-to-treat analysis (mean difference -1.26, 95% CI -2.2 to -0.32; p=0.01).

CONCLUSION

CPAP did not improve Paced Auditory Serial Addition Task scores but significantly reduced sleepiness after acute quadriplegia.

TRIAL REGISTRATION NUMBER

ACTRN12605000799651.

A randomised controlled trial of nasal decongestant to treat obstructive sleep apnoea in people with cervical spinal cord injury

STUDY DESIGN

Prospective, double-blind, randomised, placebo-controlled, cross-over trial of nasal decongestion in tetraplegia.

OBJECTIVES

Tetraplegia is complicated by severe, predominantly obstructive, sleep apnoea. First-line therapy for obstructive sleep apnoea is nasal continuous positive airway pressure, but this is poorly tolerated. High nasal resistance associated with unopposed parasympathetic activation of the upper airway contributes to poor adherence. This preliminary study tested whether reducing nasal decongestion improved sleep.

SETTING

Participants' homes in Melbourne and Sydney, Australia.

METHODS

Two sleep studies were performed in participants' homes separated by 1 week. Participants were given a nasal spray (0.5 mL of 5% phenylephrine or placebo) in random order and posterior nasal resistance measured immediately. Outcomes included sleep apnoea severity, perceived nasal congestion, sleep quality and oxygenation during sleep.

RESULTS

Twelve middle-aged (average (SD) 52 (12) years) overweight (body mass index 25.3 (6.7) kg/m²) men (C4-6, AIS A and B) participated. Nasal resistance was reduced following administration of phenylephrine (p = 0.02; mean between treatment group difference -5.20: 95% confidence interval -9.09, -1.32 cmH₂O/L/s). No differences were observed in the apnoea hypopnoea index (p = 0.15; -6.37: -33.3, 20.6 events/h), total sleep time (p = 0.49; -1.33: -51.8, 49.1 min), REM sleep% (p = 0.50; 2.37: -5.6, 10.3), arousal index (p = 0.76; 1.15: -17.45, 19.75), 4% oxygen desaturation index (p = 0.88; 0.63: -23.5, 24.7 events/h), or the percentage of mouth breathing events (p = 0.4; -8.07: -29.2, 13.0) between treatments. The apnoea hypopnoea index did differ between groups, however, all except one participant had proportionally more hypopnoeas than apnoeas during sleep after decongestion.

CONCLUSIONS

These preliminary data found that phenylephrine acutely reduced nasal resistance but did not significantly change sleep-disordered breathing severity.

Worth the effort? Weighing up the benefit and burden of continuous positive airway pressure therapy for the treatment of obstructive sleep apnoea in chronic tetraplegia

STUDY DESIGN

Mixed methods OBJECTIVES: Continuous positive airway pressure (CPAP) therapy is the recommended treatment for obstructive sleep apnoea (OSA). The aim of this study was to estimate CPAP adherence in people with tetraplegia and OSA, and to explore the barriers and facilitators to CPAP use.

SETTING

Hospital outpatient department in Melbourne, Australia METHODS: People with chronic tetraplegia and OSA were commenced with auto-titrating CPAP and supported for 1 month. Semi-structured interviews were conducted with participants at one month and analysed thematically. CPAP usage was measured at 1, 6 and 12 months, with "adherent" defined as achieving more than 4 h average per night.

RESULTS

Sixteen participants completed the study (80% male; mean age 56 (SD = 15)). Mean nightly CPAP use at one month was 3.1 h (SD = 2.5; 38% adherent), and at 6 months and 12 months were 2.6 h (SD = 2.8; 25% adherent) and 2.1 h (SD = 3.2; 25% adherent). The perceived benefit/burden balance strongly influenced ongoing use. Burden attributed to CPAP use was common, and included mask discomfort, and physical and emotional problems. Adherent participants were motivated by the immediate daytime benefits to mood, alertness and sleepiness. There was a tendency to not recognise symptoms of OSA until after they were treated.

CONCLUSION

CPAP use is challenging for people with tetraplegia, who experience substantial burden from using the device. When tolerated, the proximate benefits are substantial. People with tetraplegia need more intensive support for longer to help them overcome the burdens of CPAP and benefit from the treatment.

Sleep-Disordered Breathing and Spinal Cord Injury: A State-of-the-Art Review

Individuals living with spinal cord injury or disease (SCI/D) are at increased risk for sleep-disordered breathing (SDB), with a prevalence that is three- to fourfold higher than the general population. The main features of SDB, including intermittent hypoxemia and sleep fragmentation, have been linked to adverse cardiovascular outcomes including nocturnal hypertension in patients with SCI/D. The relationship between SDB and SCI/D may be multifactorial in nature given that level and completeness of injury can affect central control of respiration and upper airway collapsibility differently, promoting central and/or obstructive types of SDB. Despite the strong association between SDB and SCI/D, access to diagnosis and management remains limited. This review explores the role of SCI/D in the pathogenesis of SDB, poor sleep quality, the barriers in diagnosing and managing SDB in SCI/D, and the alternative approaches and future directions in the treatment of SDB, such as novel pharmacologic and nonpharmacologic treatments.

Genioglossus reflex responses to negative upper airway pressure are altered in people with tetraplegia and obstructive sleep apnoea

KEY POINTS

Protective reflexes in the throat area (upper airway) are crucial for breathing. Impairment of these reflexes can cause breathing problems during sleep such as obstructive sleep apnoea (OSA). OSA is very common in people with spinal cord injury for unknown reasons. This study shows major changes in protective reflexes that serve to keep the upper airway open in response to suction pressures in people with tetraplegia and OSA. These results help us understand why OSA is so common in people with tetraplegia and provide new insight into how protective upper airway reflexes work more broadly.

ABSTRACT

More than 60% of people with tetraplegia have obstructive sleep apnoea (OSA). However, the specific causes are unknown. Genioglossus, the largest upper-airway dilator muscle, is important in maintaining upper-airway patency. Impaired genioglossus muscle function following spinal cord injury may contribute to OSA. This study aimed to determine if genioglossus reflex responses to negative upper-airway pressure are altered in people with OSA and tetraplegia compared to non-neurologically impaired able-bodied individuals with OSA. Genioglossus reflex responses measured via intramuscular electrodes to ∼60 brief (250 ms) pulses of negative upper-airway pressure (∼-15 cmH₂ O at the mask) were compared between 13 participants (2 females) with tetraplegia plus OSA and 9 able-bodied controls (2 females) matched for age and OSA severity. The initial short-latency excitatory reflex response was absent in 6/13 people with tetraplegia and 1/9 controls. Genioglossus reflex inhibition in the absence of excitation was observed in three people with tetraplegia and none of the controls. When the excitatory response was present, it was significantly delayed in the tetraplegia group compared to able-bodied controls: excitation onset latency (mean ± SD) was 32 ± 16 vs. 18 ± 9 ms, P = 0.045; peak excitation latency was 48 ± 17 vs. 33 ± 8 ms, P = 0.038. However, when present, amplitude of the excitation response was not different between groups, 195 ± 26 vs. 219 ± 98% at baseline, P = 0.55. There are major differences in genioglossus reflex morphology and timing in response to rapid changes in airway pressure in people with tetraplegia and OSA. Altered genioglossus function may contribute to the increased risk of OSA in people with tetraplegia. The precise mechanisms mediating these differences are unknown.

Positive airway pressure therapy for sleep-disordered breathing confers short-term benefits to patients with spinal cord injury despite widely ranging patterns of use

STUDY DESIGN

Prospective, cohort study.

OBJECTIVES

To evaluate the effectiveness of bi-level positive airway pressure (PAP) therapy and the patterns of use for sleep-disordered breathing (SDB) in individuals with spinal cord injury (SCI).

SETTING

Academic tertiary care center, USA.

METHODS

Overall, 91 adults with C1-T6 SCI for ≥3 months were recruited and 74 remained in the study to be evaluated for SDB and follow-up. Individuals with SDB but no nocturnal hypercapnia (NH) were prescribed auto-titrating PAP. Those with NH were prescribed PAP with volume-assured pressure support. Device downloads and overnight transcutaneous capnography were performed at 3, 6, and 12 months to quantify PAP use and effectiveness. Participants kept daily event logs, and quality of life (QOL) questionnaires were performed after 3, 6, and 12 months.

RESULTS

Overall, 45% of 91 participants completed the study. There was great diversity among SCI patients in PAP utilization; after 3 months, 37.8% of participants used PAP for ≥70% nights and ≥240 min per night, whereas 42.2% seldom used PAP and 20% used PAP sporadically or for short periods. PAP therapy was effective in improving OSA in 89% and nocturnal hypercapnia in 77%. Higher PAP pressures predicted higher levels of device use. There were marked reductions in symptoms of autonomic dysreflexia (AD) and orthostatic hypotension as well as some improved indices of QOL.

CONCLUSIONS

Despite widely diverse patterns of use, PAP therapy may have short-term benefits with regard to QOL and reducing episodes of dizziness and autonomic dysreflexia.

Poor sleep in adults with pediatric-onset spinal cord injury: associations with pain, health, and activity

OBJECTIVE

To investigate medical complications that increase risk for poor sleep in adults with pediatric-onset spinal cord injury (SCI) and explore the relation of poor sleep to psychosocial outcomes.

METHOD

This was a cross-sectional study of individuals with pediatric-onset SCI interviewed between 2011-2015. Participants were recruited from a pediatric specialty hospital and answered questions about demographics, injury characteristics, pain, and medical complications and completed standardized outcome measures, including: Pittsburgh Sleep Quality Index, SF12v2 Health Survey, Craig Handicap Assessment and Recording Technique (CHART), and Subjective Happiness Scale.

RESULTS

The study included 180 participants between the ages of 19 and 51 (M=34.20 y; SD=7.28) who sustained their SCI before the age of 19 (M=13.48y; SD=4.59). Participants were predominantly male (62%) and Caucasian (84%). A majority had tetraplegia (56%) and complete injuries (74%). Poor sleep occurred with greater frequency in those with tetraplegia and who were unemployed. Neck (OR=2.80, P = 0.001), shoulder (OR=2.15, P = 0.011), arm (OR=3.06, P = 0.004), and lower extremity pain (OR=2.72, P = 0.004) were associated with increased risk of poor sleep. In a logistic regression analysis, chronic medical conditions and continuous pain were most likely to be associated with poor sleep. Individuals with poor sleep reported lower levels of mobility, perceived health, and subjective happiness.

CONCLUSION

Pain and secondary complications significantly increase the odds of poor sleep. Furthermore, poor sleep is associated with decreased mobility and measures of well-being. Preventive measures to reduce risk factors and improve sleep quality after pediatric-onset SCI should be considered.

Nasal Resistance Is Elevated in People with Tetraplegia and Is Reduced by Topical Sympathomimetic Administration

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is common in individuals with tetraplegia and associated with adverse health outcomes. The causes of the high prevalence of OSA in this population are unknown, but it is important to understand as standard treatments are poorly tolerated in tetraplegia. Nasal congestion is common in tetraplegia, possibly because of unopposed parasympathetic activity. Further, nasal obstruction can induce OSA in healthy individuals. We therefore aimed to compare nasal resistance before and after topical administration of a sympathomimetic between 10 individuals with tetraplegia (T) and 9 able-bodied (AB) controls matched for OSA severity, gender, and age.

METHODS

Nasal, pharyngeal, and total upper airway resistance were calculated before and every 2 minutes following delivery of ≈0.05 mL of 0.5% atomized phenylephrine to the nostrils and pharyngeal airway. The surface tension of the upper airway lining liquid was also assessed.

RESULTS

At baseline, individuals with tetraplegia had elevated nasal resistance (T = 7.0 ± 1.9, AB = 3.0 ± 0.6 cm H2O/L/s), that rapidly fell after phenylephrine (T = 2.3 ± 0.4, p = 0.03 at 2 min) whereas the able-bodied did not change (AB = 2.5 ± 0.5 cm H2O/L/s, p = 0.06 at 2 min). Pharyngeal resistance was non-significantly higher in individuals with tetraplegia than controls at baseline (T = 2.6 ± 0.9, AB = 1.2 ± 0.4 cm H2O/L/s) and was not altered by phenylephrine in either group. The surface tension of the upper airway lining liquid did not differ between groups (T = 64.3 ± 1.0, AB = 62.7 ± 0.6 mN/m).

CONCLUSIONS

These data suggest that the unopposed parasympathetic activity in tetraplegia increases nasal resistance, potentially contributing to the high occurrence of OSA in this population.

Prevalence of depression, fatigue, and sleep disturbances in patients with myelopathy: Their relation with functional and neurological recovery

OBJECTIVES

To observe the prevalence of fatigue, depression, and sleep disturbance in patients with myelopathy and their correlation with neurological and functional recovery.

PATIENTS AND METHODS

Study conducted in a university tertiary research hospital with 127 patients with myelopathy (92 males) admitted to neurorehabilitation unit between January 2010 and December 2013. Mean age was 32.71 ± 13.08 years (range 15-65 years), and mean duration of injury was 76.22 ± 82.5 days (range 14-365 days). Functional status and impairments were assessed using Barthel Index and Spinal Cord Independence Measures. Depression, fatigue, and sleep disturbances were assessed using Hospital Anxiety and Depression Scale, Fatigue Severity Scale, and Pittsburgh Sleep Quality Index scales, respectively. Neurological recovery was assessed using American Spinal Injury Association's impairment scale.

RESULTS

Forty-four out of 104 (42%) patients had borderline or confirmed depression, 36/108 (33%) had significant fatigue, and 62/106 (58%) had significant sleep disturbances at admission. Significant correlation was observed between change in fatigue and depression scores with change in functional status scores (P < 0.05) but no correlation (P > 0.05) between change in sleep disturbance scores and functional status score and neurological recovery (P > 0.05). Similarly, change in fatigue and depression scores had no correlation with neurological status improvement. Fatigue, depression, and sleep disturbance scores showed significant improvement, that is, admission vs. discharge scores (P < 0.05) with significant correlation between improvement in all three variables (P < 0.05).

CONCLUSIONS

Study variables showed significant improvement in the present study with myelopathy patients but not necessarily correlating with functional and neurological recovery.

High nasal resistance is stable over time but poorly perceived in people with tetraplegia and obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is highly prevalent in people with tetraplegia. Nasal congestion, a risk factor for OSA, is common in people with tetraplegia. The purpose of this study was to quantify objective and perceived nasal resistance and its stability over four separate days in people with tetraplegia and OSA (n=8) compared to able-bodied controls (n=6). Awake nasal resistance was quantified using gold standard choanal pressure recordings (days 1 and 4) and anterior rhinomanometry (all visits). Nasal resistance (choanal pressure) was higher in people with tetraplegia versus controls (5.3[6.5] vs. 2.1[2.4] cmH₂O/L/s, p=0.02) yet perceived nasal congestion (modified Borg score) was similar (0.5[1.8] vs. 0.5[2.0], p=0.8). Nasal resistance was stable over time in both groups (CV=0.23±0.09 vs. 0.16±0.08, p=0.2). These findings are consistent with autonomic dysfunction in tetraplegia and adaptation of perception to high nasal resistance. Nasal resistance may be an important therapeutic target for OSA in this population but self-assessment cannot reliably identify those most at risk.

Sleep onset hypoventilation in chronic spinal cord injury

A high prevalence of sleep-disordered breathing (SDB) after spinal cord injury (SCI) has been reported in the literature; however, the underlying mechanisms are not well understood. We sought to determine the effect of the withdrawal of the wakefulness drive to breathe on the degree of hypoventilation in SCI patients and able-bodied controls. We studied 18 subjects with chronic cervical and thoracic SCI (10 cervical, 8 thoracic SCI; 11 males; age 42.4 ± 17.1 years; body mass index 26.3 ± 4.8 kg/m²) and 17 matched able-bodied subjects. Subjects underwent polysomnography, which included quantitative measurement of ventilation, timing, and upper airway resistance (R_UA) on a breath-by-breath basis during transitions from wake to stage N1 sleep. Compared to able-bodied controls, SCI subjects had a significantly greater reduction in tidal volume during the transition from wake to N1 sleep (from 0.51 ± 0.21 to 0.32 ± 0.10 L vs. 0.47 ± 0.13 to 0.43 ± 0.12 L; respectively, P < 0.05). Moreover, end-tidal CO₂ and end-tidal O₂ were significantly altered from wake to sleep in SCI (38.9 ± 2.7 mmHg vs. 40.6 ± 3.4 mmHg; 94.1 ± 7.1 mmHg vs. 91.2 ± 8.3 mmHg; respectively, P < 0.05), but not in able-bodied controls (39.5 ± 3.2 mmHg vs. 39.9 ± 3.2 mmHg; 99.4 ± 5.4 mmHg vs. 98.9 ± 6.1 mmHg; respectively, P = ns). R_UA was not significantly altered in either group. In conclusion, individuals with SCI experience hypoventilation at sleep onset, which cannot be explained by upper airway mechanics. Sleep onset hypoventilation may contribute to the development SDB in the SCI population.

Simplified Approach to Diagnosing Sleep-Disordered Breathing and Nocturnal Hypercapnia in Individuals With Spinal Cord Injury

OBJECTIVE

To evaluate a strategy of home-based testing to diagnose sleep-disordered breathing and nocturnal hypercapnia in individuals with spinal cord injury (SCI).

DESIGN

Case series.

SETTING

Referral center.

PARTICIPANTS

Adults with C1-T6 SCI (N=81). Individuals were eligible if ≥ 18 years old, with SCI of ≥ 3 months' duration, living within 100 miles of the study site, and not meeting exclusion criteria. Of the 161 individuals recruited from the SCI Model System database who were not enrolled, reasons were not interested in participating, change of location, prior positive pressure ventilation use, or medical contraindication. Ten individuals did not complete the study.

INTERVENTIONS

Performance of an unsupervised home sleep apnea test combined with transcutaneous partial pressure of carbon dioxide/oxygen saturation by pulse oximetry monitoring.

MAIN OUTCOME MEASURES

Prevalence of sleep-disordered breathing and nocturnal hypercapnia. Clinical and physiological variables were examined to determine which, if any, correlate with the severity of sleep-disordered breathing.

RESULTS

Obstructive sleep apnea (OSA) was found in 81.3% of individuals, central sleep apnea (CSA) was found in 23.8%, and nonspecific hypopnea events, where respiratory effort was too uncertain to classify, were present in 35%. Nonspecific hypopnea events correlated strongly with CSA but weakly with OSA, suggesting that conventional sleep apnea test scoring may underestimate central/neuromuscular hypopneas. Nocturnal hypercapnia was present in 28% and oxygen desaturation in 18.3%. Neck circumference was the primary predictor for OSA, whereas baclofen use and obstructive apnea/hypopnea index weakly predicted CSA. Awake transcutaneous partial pressure of carbon dioxide and CSA were only marginally associated with nocturnal hypercapnia.

CONCLUSIONS

Unsupervised home sleep apnea testing with transcutaneous capnography effectively identifies sleep-disordered breathing and nocturnal hypercapnia in individuals with SCI.

Sleep apnea and periodic leg movements in the first year after spinal cord injury

BACKGROUND

Sleep disturbances are frequently reported by patients with spinal cord injury (SCI). Studies have shown an increased incidence of sleep-disordered breathing (SDB) and periodic leg movements during sleep (PLMS) in people with stable long-term SCI.

METHODS

This was a prospective observational study in order to evaluate the features and possible predisposing factors of SDB and PLMS in a heterogenic population of consecutive SCI patients admitted at the Spinal Unit of the Niguarda Hospital within the first year after injury. Each patient underwent a clinical assessment, full polysomnography, and arterial blood gas analysis before and immediately after sleep. Multiple logistic regressions were applied in order to evaluate factors associated with SDB and PLMS.

RESULTS

Thirty-five (15 tetraplegic and 20 paraplegic) patients were enrolled. Nine patients (25.7%) had an obstructive SDB and 10 (28.6%) had PLMS. The frequency of SDB was higher in tetraplegic with respect to paraplegic patients (Wald statistic: 7.71; P = 0.0055), whereas PLMs were significantly more frequent in patients with an incomplete motor lesion than in subjects with a complete motor lesion (Wald statistic: 6.14; P = 0.013).

CONCLUSION

This study confirms a high frequency of SDB and PLMS in SCI patients in the first year following injury. Independently from possible sub-acute and chronic clinical variables, the level and the completeness of the spinal cord lesion are the main factors associated respectively with an early development of SDB and PLMS.

Reprint of "Drawing breath without the command of effectors: the control of respiration following spinal cord injury"

The maintenance of blood gas and pH homeostasis is essential to life. As such breathing, and the mechanisms which control ventilation, must be tightly regulated yet highly plastic and dynamic. However, injury to the spinal cord prevents the medullary areas which control respiration from connecting to respiratory effectors and feedback mechanisms below the level of the lesion. This trauma typically leads to severe and permanent functional deficits in the respiratory motor system. However, endogenous mechanisms of plasticity occur following spinal cord injury to facilitate respiration and help recover pulmonary ventilation. These mechanisms include the activation of spared or latent pathways, endogenous sprouting or synaptogenesis, and the possible formation of new respiratory control centres. Acting in combination, these processes provide a means to facilitate respiratory support following spinal cord trauma. However, they are by no means sufficient to return pulmonary function to pre-injury levels. A major challenge in the study of spinal cord injury is to understand and enhance the systems of endogenous plasticity which arise to facilitate respiration to mediate effective treatments for pulmonary dysfunction.

Respiratory motor function in seated and supine positions in individuals with chronic spinal cord injury

This case-controlled clinical study was undertaken to investigate to what extent pulmonary function in individuals with chronic spinal cord injury (SCI) is affected by posture. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), maximal inspiratory pressure (PImax) and maximal expiratory pressure (PEmax) were obtained from 27 individuals with chronic motor-complete (n=13, complete group) and motor-incomplete (n=14, incomplete group) C2-T12 SCI in both seated and supine positions. Seated-to-supine changes in spirometrical (FVC and FEV1) and airway pressure (PImax and PEmax) outcome measures had different dynamics when compared in complete and incomplete groups. Patients with motor-complete SCI had tendency to increase spirometrical outcomes in supine position showing significant increase in FVC (p=.007), whereas patients in incomplete group exhibited decrease in these values with significant decreases in FEV1 (p=.002). At the same time, the airway pressure values were decreased in supine position in both groups with significant decrease in PEmax (p=.031) in complete group and significant decrease in PImax (p=.042) in incomplete group. In addition, seated-to-supine percent change of PImax was strongly correlated with neurological level of motor-complete SCI (ρ=-.77, p=.002). These results indicate that postural effects on respiratory performance in patients with SCI can depend on severity and neurological level of SCI, and that these effects differ depending on respiratory tasks. Further studies with adequate sample size are needed to investigate these effects in clinically specific groups and to study the mechanisms of such effects on specific respiratory outcome measures.

Human factors/usability barriers to home medical devices among individuals with disabling conditions: in-depth interviews with positive airway pressure device users

BACKGROUND

Evidence suggests that medical equipment often fails to accommodate the needs of individuals with disabling conditions. Few studies have focused on the accessibility of home medical devices such as positive airway pressure (PAP), which is a type of home medical equipment prescribed for long-term therapy.

OBJECTIVE

The purpose of this study was to explore in detail the types of difficulties experienced by patients with physical/sensory impairments who use PAP devices, as an initial step in designing a questionnaire to survey users about this topic.

METHODS

In this descriptive study, in-depth interviews were conducted with 19 participants (9 patients with physical/sensory impairment and 10 health care providers). Interviews were coded and analyzed for major topics.

RESULTS

Participants detailed the numerous ways in which current PAP devices fail to meet the needs of individuals with physical/sensory impairments (e.g., tremor, poor depth perception, paresis), by requiring patients to perform manually difficult tasks, such as inserting PAP parts through small apertures, attaching parts using a twisting motion, and lifting arms overhead to apply PAP headgear. These demands contributed to patients' frustration with and reduced usage of the home medical device.

CONCLUSIONS

Our findings suggest that home medical devices such as PAP may not be currently designed to meet the needs of some users with physical/sensory impairments. Additional studies are needed to measure the prevalence and impact of impairment-related barriers on PAP adherence for this common medical equipment.

Sleep disordered breathing in chronic spinal cord injury

STUDY OBJECTIVES

Spinal cord injury (SCI) is associated with 2-5 times greater prevalence of sleep disordered breathing (SDB) than the general population. The contribution of SCI on sleep and breathing at different levels of injury using two scoring methods has not been assessed. The objectives of this study were to characterize the sleep disturbances in the SCI population and the associated physiological abnormalities using quantitative polysomnography and to determine the contribution of SCI level on the SDB mechanism.

METHODS

We studied 26 consecutive patients with SCI (8 females; age 42.5 ± 15.5 years; BMI 25.9 ± 4.9 kg/m2; 15 cervical and 11 thoracic levels) by spirometry, a battery of questionnaires and by attended polysomnography with flow and pharyngeal pressure measurements. Inclusion criteria for SCI: chronic SCI (> 6 months post injury), level T6 and above and not on mechanical ventilation. Ventilation, end-tidal CO2 (PETCO2), variability in minute ventilation (VI-CV) and upper airway resistance (RUA) were monitored during wakefulness and NREM sleep in all subjects. Each subject completed brief history and exam, Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), Berlin questionnaire (BQ) and fatigue severity scale (FSS). Sleep studies were scored twice, first using standard 2007 American Academy of Sleep Medicine (AASM) criteria and second using new 2012 recommended AASM criteria.

RESULTS

Mean PSQI was increased to 10.3 ± 3.7 in SCI patients and 92% had poor sleep quality. Mean ESS was increased 10.4 ± 4.4 in SCI patients and excessive daytime sleepiness (ESS ≥ 10) was present in 59% of the patients. Daytime fatigue (FSS > 20) was reported in 96% of SCI, while only 46% had high-risk score of SDB on BQ. Forced vital capacity (FVC) in SCI was reduced to 70.5% predicted in supine compared to 78.5% predicted in upright positions (p < 0.05). Likewise forced expiratory volume in first second (FEV1) was 64.9% predicted in supine compared to 74.7% predicted in upright positions (p < 0.05). Mean AHI in SCI patients was 29.3 ± 25.0 vs. 20.0 ± 22.8 events/h using the new and conventional AASM scoring criteria, respectively (p < 0.001). SCI patients had SDB (AHI > 5 events/h) in 77% of the cases using the new AASM scoring criteria compared to 65% using standard conventional criteria (p < 0.05). In cervical SCI, VI decreased from 7.2 ± 1.6 to 5.5 ± 1.3 L/min, whereas PETCO2 and VI-CV, increased during sleep compared to thoracic SCI.

CONCLUSION

The majority of SCI survivors have symptomatic SDB and poor sleep that may be missed if not carefully assessed. Decreased VI and increased PETCO2 during sleep in patients with cervical SCI relative to thoracic SCI suggests that sleep related hypoventilation may contribute to the pathogenesis SDB in patients with chronic cervical SCI.

Auto-titrating continuous positive airway pressure treatment for obstructive sleep apnoea after acute quadriplegia (COSAQ): study protocol for a randomized controlled trial

Background

Quadriplegia is a severe, catastrophic injury that predominantly affects people early in life, resulting in lifelong physical disability. Obstructive sleep apnoea is a direct consequence of quadriplegia and is associated with neurocognitive deficits, sleepiness and reduced quality of life. The usual treatment for sleep apnoea is nasal continuous positive airway pressure (CPAP); however, this is poorly tolerated in quadriplegia. To encourage patients to use this therapy, we have to demonstrate that the benefits outweigh the inconvenience. We therefore propose a prospective, multinational randomized controlled trial of three months of CPAP for obstructive sleep apnoea after acute quadriplegia.

Methods/design

Specialist spinal cord injury centres across Australia, New Zealand, the UK and Canada will recruit medically stable individuals who have sustained a (new) traumatic quadriplegia (complete or incomplete second cervical to first thoracic level lesions). Participants will be screened for obstructive sleep apnoea using full, portable sleep studies. Those with an apnoea hypopnoea index greater than 10 per hour will proceed to an initial three-night trial of CPAP. Those who can tolerate CPAP for at least 4 hours on at least one night of the initial trial will be randomized to either usual care or a 3-month period of auto-titrating CPAP. The primary hypothesis is that nocturnal CPAP will improve neuropsychological functioning more than usual care alone. The secondary hypothesis is that the magnitude of improvement of neuropsychological function will be predicted by the severity of baseline sleepiness measures, sleep fragmentation and sleep apnoea. Neuropsychological tests and full polysomnography will be performed at baseline and 3 months with interim measures of sleepiness and symptoms of autonomic dysfunction measured weekly. Spirometry will be performed monthly. Neuropsychological tests will be administered by blinded assessors. Recruitment commenced in July 2009.

Discussion

The results of this trial will demonstrate the effect of nocturnal CPAP treatment of obstructive sleep apnoea in acute quadriplegia. If CPAP can improve neurocognitive function after injury, it is likely that rehabilitation and subsequent community participation will be substantially improved for this group of predominantly young and severely physically disabled people.

Trial registration

Australian New Zealand Clinical Trial Registry ACTRN12605000799651

The impact of spinal cord injury on breathing during sleep

The prevalence of sleep disordered breathing (SDB) following spinal cord injury (SCI) is considerably greater than in the general population. While the literature on this topic is still relatively small, and in some cases contradictory, a few general conclusions can be drawn. First, while both central and obstructive sleep apnea (OSA) has been reported after SCI, OSA appears to be more common. Second, SDB after SCI likely reflects a complex interplay between multiple factors including body mass, lung volume, autonomic function, sleep position, and respiratory neuroplasticity. It is not yet possible to pinpoint a "primary factor" which will predispose an individual with SCI to SDB, and the underlying mechanisms may change during progression from acute to chronic injury. Given the prevalence and potential health implications of SDB in the SCI population, we suggest that additional studies aimed at defining the underlying mechanisms are warranted.

Decentralized cardiovascular autonomic control and cognitive deficits in persons with spinal cord injury

Spinal cord injury (SCI) results in motor and sensory impairments that can be identified with the American Spinal Injury Association (ASIA) Impairment Scale (AIS). Although, SCI may disrupt autonomic neural transmission, less is understood regarding the clinical impact of decentralized autonomic control. Cardiovascular regulation may be altered following SCI and the degree of impairment may or may not relate to the level of AIS injury classification. In general, persons with lesions above T1 present with bradycardia, hypotension, and orthostatic hypotension; functional changes which may interfere with rehabilitation efforts. Although many individuals with SCI above T1 remain overtly asymptomatic to hypotension, we have documented deficits in memory and attention processing speed in hypotensive individuals with SCI compared to a normotensive SCI cohort. Reduced resting cerebral blood flow (CBF) and diminished CBF responses to cognitive testing relate to test performance in hypotensive non-SCI, and preliminary evidence suggests a similar association in individuals with SCI. Persons with paraplegia below T7 generally present with a normal cardiovascular profile; however, our group and others have documented persistently elevated heart rate and increased arterial stiffness. In the non-SCI literature there is evidence supporting a link between increased arterial stiffness and cognitive deficits. Preliminary evidence suggests increased incidence of cognitive impairment in individuals with paraplegia, which we believe may relate to adverse cardiovascular changes. This report reviews relevant literature and discusses findings related to the possible association between decentralized cardiovascular autonomic control and cognitive dysfunction in persons with SCI.

Continuous positive airway pressure requirements in patients with tetraplegia and obstructive sleep apnoea

STUDY DESIGN

Clinic-based retrospective case-control study.

OBJECTIVES

To compare continuous positive airway pressure (CPAP) requirements between patients with tetraplegia and able-bodied patients with obstructive sleep apnoea (OSA).

SETTING

Melbourne, Australia.

METHODS

Diagnostic and CPAP titration polysomnograms of 219 able-bodied, and 25 patients with tetraplegia and OSA were compared for apnoea hypopnoea index (AHI) and CPAP levels required to effectively treat OSA. Demographics and body mass index (BMI) were obtained for each patient. ASIA score and injury date were obtained for patients with tetraplegia.

RESULTS

There was no significant difference in AHI (P=0.102) between the two groups; however, able-bodied patients were significantly older (P=0.003), required significantly higher levels of CPAP to control their OSA (P<0.001) and had higher BMIs (P=0.009) than patients with tetraplegia. In the tetraplegia group, there was no significant correlation between AHI and effective CPAP (r=0.022, P=0.92) or between AHI and BMI (r=-0.196, P=0.35). There was a significant correlation between effective CPAP and BMI (r=0.411, P=0.041). Among able-bodied patients, over two-thirds (68.8%) required 10-16 cm H(2)0 to control their OSA and nearly one-third required over 16 cm H(2)0. In contrast, over two-thirds (68.8%) in the tetraplegia group required less than 10 cm H(2)0 of CPAP to control their OSA.

CONCLUSION

This retrospective study suggests that OSA patients with tetraplegia require significantly less CPAP to treat their OSA at any given AHI than those who are able-bodied. This suggests that additional unknown factors may contribute to the high prevalence of OSA in tetraplegia.

Dysfunctional sleep in persons with spinal cord injuries and disorders

STUDY DESIGN

Cross-sectional survey of veterans with spinal cord injuries and disorders (SCI/D).

OBJECTIVES

To describe sleep dysfunction (independent of sleep apnea) in persons with traumatic and non-traumatic SCI/D, and to examine characteristics and health outcomes independently associated with sleep dysfunction unrelated to sleep apnea.

SETTING

Seven Veterans Affairs SCI care facilities in the United States.

METHODS

Mailed cross-sectional survey with follow-up calls completed by end of 2008. Bivariate analyses to compare measures outcomes in persons with SCI/D who were dysfunctional sleepers vs those who were not. Multivariate logistic regression used to identify variables independently associated with dysfunctional sleep in veterans with SCI/D.

RESULTS

Overall, 49% of the sample had sleep dysfunction unrelated to sleep apnea. In this subgroup, bivariate analyses showed that a greater proportion of dysfunctional sleepers than non-dysfunctional sleepers were current smokers, had problems with drinking alcohol, hypertension, asthma, chronic obstructive pulmonary disease (COPD) and problematic weight gain. Variables independently associated with higher odds of dysfunctional sleep included white race, being a current smoker, problems with drinking alcohol, asthma, COPD and problematic weight gain.

CONCLUSION

Consistent with epidemiological evidence for the general population, we found significant associations of sleep dysfunction with weight gain, smoking, alcohol misuse and select chronic conditions (COPD, asthma). Sustained sleep dysfunction may contribute to health deterioration and mortality, highlighting the need to address the high prevalence of sleep dysfunction (independent of sleep apnea) in persons with SCI/D. In particular, efforts aimed at modifying problematic weight gain, alcohol misuse and smoking are warranted in this cohort to improve sleep.

Complete absence of evening melatonin increase in tetraplegics

Individuals with a spinal cord injury (SCI), especially with tetraplegia, experience poor sleep quality, and this may be related to impaired control of circadian rhythmicity. Here, we examined the evening onset of melatonin secretion, an important hormone for the initiation of sleep, in people with a complete cervical (tetraplegia) and thoracic (paraplegia) SCI, and age- and sex-matched able-bodied control participants. Multiple samples of salivary melatonin were obtained during the evening hours and analyzed by ELISA methods in 10 control partcipants, 9 individuals with paraplegia, and 6 individuals with tetraplegia. Sleep quality was assessed using questionnaires. Interactive effects of group and time were found for melatonin levels (P=0.022). In the control and paraplegia groups, the mean melatonin level increased significantly from 2.59 ± 1.04 and 4.28 ± 3.28 pg/ml at 7 PM to 10.62 ± 4.59 and 13.10 ± 7.39 pg/ml at 11 PM, respectively (P<0.001). In the tetraplegia group, melatonin level was 5.25 ± 3.72 at 7 PM but only 2.41 ± 1.25 pg/ml at 11 PM (P>0.05). Decreased sleep quality was more prevalent in individuals with tetraplegia (83%) and paraplegia (75%) compared with controls (20%; P=0.02). Unlike in the control and paraplegia groups, the evening increase in melatonin concentration was completely absent in the tetraplegia group. This provides biological insight into sleep regulation in humans and provides better understanding of the poor sleep quality in people with tetraplegia.

Relationships between objective sleep indices and symptoms in a community sample of people with tetraplegia

OBJECTIVE

To examine the relationships between injury severity, quality of life, sleep symptoms, objectively measured sleep, and sleep disorders in chronic tetraplegia.

DESIGN

Cross-sectional survey.

SETTING

Community.

PARTICIPANTS

People with tetraplegia (N=78; 59 men, 35 with motor and sensory complete tetraplegia; mean age ± SD, 43±12.1; age range 18-70y), living in the state of Victoria, Australia, who were not currently being treated for sleep disorders and who completed both questionnaires and sleep studies comprised the study cohort.

INTERVENTION

Questionnaire battery mailed to potential participants. Returned questionnaires were followed with full, home-based polysomnography.

MAIN OUTCOME MEASURES

Demographics and questionnaire responses.

RESULTS

Quality of life (Assessment of Quality of Life instrument) was worse in the group with complete lesions compared with incomplete lesions (P=.001; median=16; interquartile range, 9 vs 12 [12]), and the Apnea-Hypopnea Index was higher (P=.002; interquartile range, 32.0 [25.2] vs 13.2 [24.8]). Ninety-one percent of those with complete lesions had obstructive sleep apnea (Apnea-Hypopnea Index >10) versus 55.8% of those with incomplete tetraplegia. No effect of lesion level on the Apnea-Hypopnea Index was observed (r=-.04, P=.73). In the complete group, the time taken from sleep onset until the first rapid eye movement sleep period was significantly delayed at over 2 hours. Multiple regression analyses showed substantially stronger relationships between daytime sleep complaints and abnormalities observed in the sleep study in those with complete lesions.

CONCLUSIONS

Obstructive sleep apnea is a major problem, particularly in those with complete tetraplegia, and this single comorbidity is associated with reduced quality of life. In those with incomplete cervical lesions, the relationships between sleepiness, other sleep symptoms, and polysomnography indices are less precise.

Sleep problems in individuals with spinal cord injury: frequency and age effects

OBJECTIVES

The two objectives of this study were (a) to replicate the previous finding of more severe sleep difficulties in a sample of individuals with spinal cord injury (SCI) compared with normative samples, and (b) to examine the associations between aging variables (specifically, chronological age, duration of SCI, age at SCI onset) and the severity of sleep difficulties.

DESIGN

Cross-sectional survey.

RESEARCH METHOD

A survey was administered to 620 individuals with SCI that included measures of demographic characteristics and sleep difficulties.

RESULTS

The findings indicated that sleep problems are more common in individuals with SCI than in normative samples. In addition, younger participants in our sample reported more sleep problems than did older participants. Duration of SCI and age at onset, however, were not significantly associated with sleep difficulties.

CONCLUSION

The analyses used in this study provide a model for examining age effects using concurrent survey data that may be useful for other investigators interested in studying the associations between age-related variables and important health-related domains.

The feasibility of using auto-titrating continuous positive airway pressure to treat obstructive sleep apnoea after acute tetraplegia

STUDY DESIGN

A prospective cohort with acute tetraplegia.

OBJECTIVES

Obstructive sleep apnoea (OSA) is common within weeks of tetraplegia. This study aimed at determining the feasibility of auto-titrating continuous positive airway pressure (CPAP) to treat OSA after acute tetraplegia.

SETTING

The Victorian Spinal Cord Service, Melbourne, Australia.

METHODS

Participants underwent full, portable polysomnography. Those with an apnoea hypopnoea index of more than 10 events per hour were defined as having OSA and were offered treatment with CPAP. Treatment adherence was objectively monitored, and measures of quality of life, sleepiness and functional outcomes were determined at enrollment and 3 months later at study conclusion.

RESULTS

A total of 44 patients were admitted to our Spinal Cord Service over 9 months, and 19 participated. Fourteen of them had OSA and seven were adherent with therapy for 3 months. Compared with those who did not have OSA, and with those with OSA who were not adherent with CPAP, those who adhered to CPAP were older (mean (s.d.) age 54 years (13) versus non-adherent 28 years (15) and no OSA 29 years (10)) and heavier (body mass index (BMI) 32.5 (11.7), 24.1 (3.7) and 20.6 (3.1), respectively). CPAP-adherant patients and those without OSA showed a 50% or greater improvement in their state sleepiness over the 3 months. Patients with OSA who did not tolerate CPAP had no improvement in sleepiness.

CONCLUSION

Auto-titrating CPAP is a feasible treatment for OSA in acute tetraplegia. Intensive clinical support was required initially, and a tolerance of therapy for at least 4 h for one of the first 3 days was predictive of good CPAP usage.

SPONSORSHIP

Transport Accident Commission.

Pulmonary function and spinal cord injury

Injury to the cervical and upper thoracic spinal cord disrupts function of inspiratory and expiratory muscles, as reflected by reduction in spirometric and lung volume parameters and static mouth pressures. In association, subjects with tetraplegia have decreased chest wall and lung compliance, increased abdominal wall compliance, and rib cage stiffness with paradoxical chest wall movements, all of which contribute to an increase in the work of breathing. Expiratory muscle function is more compromised than inspiratory muscle function among subjects with tetraplegia and high paraplegia, which can result in ineffective cough and propensity to mucus retention and atelectasis. Subjects with tetraplegia also demonstrate heightened vagal activity with reduction in baseline airway caliber, findings attributed to loss of sympathetic innervation to the lungs. Significant increase in airway caliber following inhalation of ipratropium bromide, an anticholinergic agent, suggests that reduction in airway caliber is not due to acquired airway fibrosis stemming from repeated infections or to abnormal hysteresis secondary to chronic inability of subjects to inhale to predicted total lung capacity. Reduced baseline airway caliber possibly explains why subjects with tetraplegia exhibit airway hyperresponsiveness to methacholine and ultrasonically nebulized distilled water. While it has been well demonstrated that bilateral phrenic nerve pacing or stimulation through intramuscular diaphragmatic electrodes improves inspiratory muscle function, it remains unclear if inspiratory muscle training improves pulmonary function. Recent findings suggest that expiratory muscle training, electrical stimulation of expiratory muscles and administration of a long-acting beta(2)-agonist (salmeterol) improve physiological parameters and cough. It is unknown if baseline bronchoconstriction in tetraplegia contributes to respiratory symptoms, of if the chronic administration of a bronchodilator reduces the work of breathing and/or improves respiratory symptoms. Less is known regarding the benefits of treatment of obstructive sleep apnea, despite evidence indicating that the prevalence of this condition in persons with tetraplegia is far greater than that encountered in able-bodied individuals.

Cardiomyopathy presenting as severe fatigue in a person with chronic spinal cord injury

BACKGROUND/OBJECTIVE

To describe a case of fatigue associated with cardiomyopathy in a man with spinal cord injury.

STUDY DESIGN

Case report.

SUBJECT

An obese 35-year-old man with long-term ASIA A L2 paraplegia, accompanied by a 2-year history of progressive severe fatigue.

METHODS

Physical examination showed obesity, hypertension, tachycardia, and pitting edema. An echocardiogram showed a 20% ejection fraction, severe dilation, and global hypokinesis in the left ventricle and mild to moderate mitral regurgitation.

RESULTS

Symptoms improved after treatment with furosemide, warfarin, ramipril, and continuous positive airway pressure for obstructive sleep apnea.

CONCLUSION

Severe progressive fatigue in a patient with chronic SCI may signal cardiomyopathy. Diagnostic studies may be warranted in patients with progressive fatigue.

Clinical assessment and management of obesity in individuals with spinal cord injury: a review

BACKGROUND

Diagnosing and managing obesity in individuals with spinal cord injury (SCI) remain challenging.

METHODS

Literature on the epidemiology, impact, and management of obesity in individuals with SCI was reviewed.

FINDINGS

Although nearly 66% of individuals with SCI are either overweight or obese, little guidance is available to measure and monitor obesity in the clinical setting. The use of anthropometric indices and specific cut points available for able-bodied persons is limited by the body composition changes that follow SCI. Indices of upper body obesity warrant examination in SCI because they provide an index of central obesity, which is more closely linked to some obesity-related conditions than is overall obesity. Investigations into the sequelae of excess body fat and its distribution are also needed in SCI because past research in this area has been inconclusive. Although limited, evidence regarding obesity interventions in SCI may be promising.

CONCLUSIONS

The best anthropometric tool to define obesity in the clinical setting remains unknown. SCI-specific assessment tools and a better understanding of the sequelae of excess body weight will lead to better targeting of prevention and treatment efforts. More research is needed on the individual components of a weight management program unique to SCI. Until then, providers are urged to use a team approach and draw on existing resources and applicable research in able-bodied individuals to facilitate weight management in individuals with SCI.