An evidence-based review of aging of the body systems following spinal cord injury

The use of intraoperative triggered electromyography to detect misplaced pedicle screws: a systematic review and meta-analysis

OBJECT

Insertion of instruments or implants into the spine carries a risk for injury to neural tissue. Triggered electromyography (tEMG) is an intraoperative neuromonitoring technique that involves electrical stimulation of a tool or screw and subsequent measurement of muscle action potentials from myotomes innervated by nerve roots near the stimulated instrument. The authors of this study sought to determine the ability of tEMG to detect misplaced pedicle screws (PSs).

METHODS

The authors searched the US National Library of Medicine, the Web of Science Core Collection database, and the Cochrane Central Register of Controlled Trials for PS studies. A meta-analysis of these studies was performed on a per-screw basis to determine the ability of tEMG to detect misplaced PSs. Sensitivity, specificity, and receiver operating characteristic (ROC) area under the curve (AUC) were calculated overall and in subgroups.

RESULTS

Twenty-six studies were included in the systematic review. The authors analyzed 18 studies in which tEMG was used during PS placement in the meta-analysis, representing data from 2932 patients and 15,065 screws. The overall sensitivity of tEMG for detecting misplaced PSs was 0.78, and the specificity was 0.94. The overall ROC AUC was 0.96. A tEMG current threshold of 10–12 mA (ROC AUC 0.99) and a pulse duration of 300 µsec (ROC AUC 0.97) provided the most accurate testing parameters for detecting misplaced screws. Screws most accurately conducted EMG signals (ROC AUC 0.98).

CONCLUSIONS

Triggered electromyography has very high specificity but only fair sensitivity for detecting malpositioned PSs.

SCI Longitudinal Aging Study: 40 Years of Research

BACKGROUND

The Spinal Cord Injury (SCI) Longitudinal Aging Study was initiated in 1973 and has conducted 8 assessments over the past 40 years. It was designed to help rehabilitation professionals understand the life situation of people with SCI, but it has developed into the most long-standing study of aging and SCI and has resulted in over 50 publications.

OBJECTIVE

Our purpose was to provide a detailed history of the study, response patterns, utilization of measures, and a summary of key findings reported in the literature.

METHODS

Five participant samples have been incorporated over the 40 years, with enrollment in 1973, 1984, 1993 (2 samples), and 2003. A total of 2,208 participants have completed 6,001 assessments, with a particularly large number of assessments among those who are more than 40 years post injury (n = 349).

RESULTS

The overall results have indicated changing patterns of outcomes over time as persons with SCI age, with some notable declines in participation and health. There has been a survivor effect whereby persons who are more active, well-adjusted, and healthier live longer.

CONCLUSIONS

This study has several important features that are required for longitudinal research including (a) consistency of follow-up, (b) consistency of measures over time, (c) addition of new participant samples to counteract attrition, and (d) inclusion of a large number of individuals who have reached aging milestones unparalleled in the literature. Data from this study can inform the literature on the natural course of aging with SCI.

Mortality and longevity after a spinal cord injury: systematic review and meta-analysis

BACKGROUND/AIMS

Mortality and longevity studies of spinal cord injury (SCI) are essential for informing healthcare systems and policies. This review evaluates the current evidence among people with SCIs worldwide in relation to the WHO region and country income level; demographic and lesion characteristics; and in comparison with the general population.

METHODS

A systematic review of relevant databases for original studies. Pooled estimates were derived using random effects meta-analysis, restricted to traumatic SCI.

RESULTS

Seventy-four studies were included. In-hospital mortality varied, with pooled estimates of 24.1% (95% confidence interval (CI) 14.1-38.0), 7.6% (95% CI 6.3-9.0), 7.0% (95% CI 1.5-27.4), and 2.1% (95% CI 0.9-5.0) in the WHO regions of Africa, the Americas, Europe and Western Pacific. The combined estimate for low- and middle-income countries was nearly three times higher than for high-income countries. Pooled estimates of first-year survival were 86.5% (95% CI 75.3-93.1), 95.6% (95% CI 81.0-99.1), and 94.0% (95% CI 93.3-94.6) in the Americas, Europe and Western Pacific. Pooled estimates of standardized mortality ratios in tetraplegics were 2.53 (2.00-3.21) and 2.07 (1.47-2.92) in paraplegics.

CONCLUSION

This study found substantial variation in mortality and longevity within the SCI population, compared to the general population, and between WHO regions and country income level. Improved standardization and quality of reporting is needed to improve inferences regarding the extent to which mortality outcomes following an SCI are related to healthcare systems, services and policies.

Lower-extremity muscle atrophy and fat infiltration after chronic spinal cord injury

BACKGROUND

Atrophy and fatty-infiltration of lower-extremity muscle after spinal cord injury (SCI) predisposes individuals to metabolic disease and related mortality.

OBJECTIVES

To determine the magnitude of atrophy and fatty-infiltration of lower-extremity muscles and related factors in a group of individuals with chronic SCI and diverse impairment.

METHODS

Muscle cross-sectional area and density were calculated from peripheral quantitative computed tomography scans of the 66% site of the calf of 70 participants with chronic SCI [50 male, mean age 49 (standard deviation 12) years, C2-T12, AIS A-D] and matched controls. Regression models for muscle area and density were formed using 16 potential correlates selected a priori.

RESULTS

Participants with motor-complete SCI had ≈ 32% lower muscle area, and ≈ 43% lower muscle density values relative to controls. Participants with motor-incomplete SCI had muscle area and density values that were both ≈ 14% lower than controls. Body mass (+), tetraplegia (+), motor function (+), spasticity (+), vigorous physical activity (+), wheelchair use (-), age (-), and waist circumference (-) were associated with muscle size and/or density in best-fit regression models.

CONCLUSIONS

There are modifiable factors related to muscle size, body composition, and activity level that may offer therapeutic targets for preserving metabolic health after chronic SCI.

Lifetime prevalence of chronic health conditions among persons with spinal cord injury

OBJECTIVE

To assess lifetime prevalence of 7 chronic health conditions (CHCs) among a cohort of adults with chronic traumatic spinal cord injury (SCI).

DESIGN

Cross-sectional.

SETTING

Rehabilitation hospital.

PARTICIPANTS

Adults with SCI who were ≥18 years of age, were ≥1 year postinjury, and had residual neurologic effects impeding full recovery (n=1678).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

CHCs were measured using questions from the Behavioral Risk Factor Surveillance System for diabetes (not including gestational), heart attack (also called a myocardial infarction), angina or coronary artery disease, stroke, hypertension (not including during pregnancy), high blood cholesterol, or cancer.

RESULTS

Of participants, 49.5% reported having at least 1 CHC, with 23.2% reporting ≥2 CHCs. The most frequently reported CHC was high cholesterol (29.3%) followed by hypertension (28.7%) and diabetes (11.8%). Although the prevalence of CHCs significantly increased with increasing age, only hypertension and cancer were significantly associated with years postinjury. Four CHCs (diabetes, coronary artery disease, hypertension, high cholesterol) were significantly related to mobility status as measured by injury level and ambulatory status. However, after controlling for age, years postinjury, sex, and race, mobility status became nonsignificant in relation to coronary artery disease, but it remained significantly associated with diabetes, hypertension, and high cholesterol.

CONCLUSIONS

Clinicians should be aware of the risk of CHCs in persons with SCI and should screen for these conditions and regular maintenance activities related to SCI.

Evaluation of a community reintegration outpatient program service for community-dwelling persons with spinal cord injury

Objective. To evaluate the effectiveness of a community reintegration outpatient (CROP) service for promoting well-being and community participation following spinal cord injury (SCI). Participants. Community-dwelling adults (N = 14) with traumatic and nontraumatic SCI. Interventions. The CROP service is a 12-week (1 × week; 120 minutes) interprofessional closed therapeutic education service. Main Outcome Measure(s). Moorong Self-Efficacy Scale (MSES); Impact on Participation and Autonomy (IPA); Positive Affect and Negative Affect Scale (PANAS); Coping Inventory of Stressful Situations (CISS); World Health Organization Quality of Life (WHOQOL-BREF); semistructured qualitative interviews. Methods. Twenty-one participants were recruited from two subsequent CROP services, with only 14 persons completing all data assessments. Data were collected at baseline (week 0), at exit (week 12), and at a three-month follow-up. Semistructured interviews were conducted at exit. Results. Self-efficacy (MSES) and positive affect (PANAS) improved from baseline to exit (P < .05), but the changes were not maintained at follow-up. Qualitative analysis identified four major themes related to therapeutic benefits: (1) role of self; (2) knowledge acquisition; (3) skill application; and (4) group processes. Conclusions. Participation in a therapeutic education service has the potential to improve well-being in persons with SCI, but there is a need to identify strategies to maintain long-term gains.

Gastric vagal motoneuron function is maintained following experimental spinal cord injury

BACKGROUND

Clinical reports indicate that spinal cord injury (SCI) initiates profound gastric dysfunction. Gastric reflexes involve stimulation of sensory vagal fibers, which engage brainstem circuits that modulate efferent output back to the stomach, thereby completing the vago-vagal reflex. Our recent studies in a rodent model of experimental high thoracic (T3-) SCI suggest that reduced vagal afferent sensitivity to gastrointestinal (GI) stimuli may be responsible for diminished gastric function. Nevertheless, derangements in efferent signals from the dorsal motor nucleus of the vagus (DMV) to the stomach may also account for reduced motility.

METHODS

We assessed the anatomical, neurophysiological, and functional integrity of gastric-projecting DMV neurons in T3-SCI rats using: (i) retrograde labeling of gastric-projecting DMV neurons; (ii) whole cell recordings from gastric-projecting neurons of the DMV; and, (iii) in vivo measurements of gastric contractions following unilateral microinjection of thyrotropin-releasing hormone (TRH) into the DMV.

KEY RESULTS

Immunohistochemical analysis of gastric-projecting DMV neurons demonstrated no difference between control and T3-SCI rats. Whole cell in vitro recordings showed no alteration in DMV membrane properties and the neuronal morphology of these same, neurobiotin-labeled, DMV neurons were unchanged after T3-SCI with regard to cell size and dendritic arborization. Central microinjection of TRH induced a significant facilitation of gastric contractions in both control and T3-SCI rats and there were no significant dose-dependent differences between groups.

CONCLUSIONS & INFERENCES

Our data suggest that the acute, 3 day to 1 week post-SCI, dysfunction of vagally mediated gastric reflexes do not include derangements in the efferent DMV motoneurons.

Cycles of adaptive strategies over the life course

An increasing number of Australia's ageing population are aging with long-term physical impairments. This study explored the life experiences of this group using a qualitative approach. In-depth interviews were conducted with 10 disabled Victorians, aged between 51 and 84 years, and an inductive thematic analysis undertaken. A relationship was found between the adaptive strategies that participants developed as they moved through life phases and the impairment stages. The implications of the emergence of a cyclical process of adaptation across the life course. and particularly in respect of aging, delivery of aged-care services and social workers in this sector are discussed.

Chronic thoracic spinal cord injury impairs CD8+ T-cell function by up-regulating programmed cell death-1 expression

Background

Chronic spinal cord injury (SCI) induces immune depression in patients, which contributes to their higher risk of developing infections. While defects in humoral immunity have been reported, complications in T-cell immunity during the chronic phase of SCI have not yet been explored.

Methods

To assess the impact of chronic SCI on peripheral T-cell number and function we used a mouse model of severe spinal cord contusion at thoracic level T9 and performed flow cytometry analysis on the spleen for T-cell markers along with intracellular cytokine staining. Furthermore we identified alterations in sympathetic activity in the spleen of chronic SCI mice by measuring splenic levels of tyrosine hydroxylase (TH) and norepinephrine (NE). To gain insight into the neurogenic mechanism leading to T-cell dysfunction we performed in vitro NE stimulation of T-cells followed by flow cytometry analysis for T-cell exhaustion marker.

Results

Chronic SCI impaired both CD4⁺ and CD8⁺ T-cell cytokine production. The observed T-cell dysfunction correlated with increased expression of programmed cell death 1 (PD-1) exhaustion marker on these cells. Blocking PD-1 signaling in vitro restored the CD8⁺ T-cell functional defect. In addition, we showed that chronic SCI mice had higher levels of splenic NE, which contributed to the T-cell exhaustion phenotype, as PD-1 expression on both CD4⁺ and CD8⁺ T-cells was up-regulated following sustained exposure to NE in vitro.

Conclusions

These studies indicate that alteration of sympathetic activity following chronic SCI induces CD8⁺ T-cell exhaustion, which in turn impairs T-cell function and contributes to immune depression. Inhibition of the exhaustion pathway should be considered as a new therapeutic strategy for chronic SCI-induced immune depression.

Medication before and after a spinal cord lesion

OBJECTIVE

To map the impact of spinal cord lesion (SCL) on medication.

STUDY DESIGN

Registration of medication for 72 patients before SCL and at discharge from the Department for Spinal Cord Injuries.

SETTING

Department for Spinal Cord Injuries, East Denmark.

METHODS

The changes in medication for each Anatomical Therapeutic Chemical (ATC) Classification System group were registered for all patients, who were discharged from Department for Spinal Cord Injuries during 2010. The changes in medication per se were calculated for different parts of the population: non-traumatic, traumatic patients, men, women, paraplegia, tetraplegia, American Spinal Injury Association Impairment Scale (AIS) A, B or C, AIS D, age 0-45, 46-60 and 60+. In addition, comparisons of changes in medication were made between complementary parts of the population.

RESULTS

The overall increase in medication after SCL was 3.29 times (P<0.001). Statistically significant increases were seen for most medicine categories. When studying subgroups of the population, the increase was most constantly seen for the medicine in the groups 'Alimentary tract and metabolism' and 'Nervous system'. The highest overall increases were seen in patients with AIS A, B and C compared with AIS D (P<0.05). There was no difference between traumatic and non-traumatic SCL, men and women, and younger compared with older patients.

CONCLUSION

SCL elicits a general massive need for medicine. The relative increase is most pronounced for the more severely injured (AIS A, B and C). The increase in medication may have implications for side effects and for the economy of all involved.

Mortality and causes of death after traumatic spinal cord injury in Estonia

STUDY DESIGN

Retrospective population-based study with mortality follow-up.

OBJECTIVE

To study mortality, causes and risk factors for death in Estonian patients with traumatic spinal cord injury (TSCI).

SETTING

All Estonian hospitals.

METHODS

Medical records of patients with TSCI from all regional, central, general, and rehabilitation hospitals in Estonia from 1997 to 2007, were retrospectively reviewed. Mortality status was ascertained as of 31 December 2011. Causes of death were collected from the Estonian Causes of Death Registry. Standardized mortality ratios (SMRs) were calculated for the entire sample and for causes of death. A Cox proportional hazards modeling was used to identify the risk indicators for death.

RESULTS

During the observation period (1997-2011) 162 patients of 595 died. Nearly half of the patients (n = 76) died during the first year after TSCI. The main causes of death were external causes (30%), cardiovascular disease (29%). and suicide (8%). The overall SMR was 2.81 (95% confidence interval 2.40-3.28) and SMR was higher for women than for men (3.80 vs. 2.70). Cause-specific SMRs were markedly elevated for sepsis and suicide. Mortality was significantly affected by the age at the time of injury, neurological level, and extent of the injury as well as the year of TSCI and complications.

CONCLUSION

Life expectancy is significantly decreased in patients with TSCI in Estonia compared with the general population. Deaths during the first year after the injury have an important impact on statistics. Treatment of cardiovascular diseases, infections, and prevention of suicide are useful for reducing mortality in patients with TSCI.

Frequency and age effects of secondary health conditions in individuals with spinal cord injury: a scoping review

STUDY DESIGN

Scoping review.

OBJECTIVES

To gain a better understanding of the prevalence, course and association with age of secondary health conditions in individuals with spinal cord injury (SCI).

SETTING

Seattle, Washington, USA.

METHODS

We performed searches of electronic databases for studies published from 1986-2011 that provided information regarding the prevalence, course or associations with age and duration of secondary health conditions in individuals with SCI.

RESULTS

Ninety-two studies were included. The findings indicate that: (1) individuals with SCI experience a number of secondary health conditions, many of which occur at a higher rate in those with SCI than the normative population; (2) the most common conditions or symptoms are pain, bowel and bladder regulation problems, muscle spasms, fatigue, esophageal symptom and osteoporosis; (3) a number of conditions, including cardiovascular disease, diabetes, bone mineral density loss, fatigue and respiratory complications or infections, occur with higher frequency in older individuals or those with longer SCI duration, relative to younger individuals or those with shorter SCI duration; and (4) there is a marked lack of longitudinal research examining the natural course of health conditions in individuals aging with SCI.

CONCLUSIONS

The findings support the conclusion that individuals with SCI show signs of 'premature aging' in different organ systems. Longitudinal research is needed to understand when problems are most likely to emerge, and to develop and test the efficacy of interventions to prevent these health conditions and their negative impact.

Changes in traditional chronic disease risk factors over time and their relationship with leisure-time physical activity in people living with spinal cord injury

This study examined whether levels of chronic disease risk factors change over time, and whether leisure-time physical activity (LTPA) can explain any of the variation in those risk factors that change, in a sample of community-dwelling people living with spinal cord injury (SCI) in or near Hamilton, Ontario, Canada. LTPA was measured using the Physical Activity Recall Assessment for People with SCI at baseline (n = 76 adults with chronic (≥1 year) paraplegia or tetraplegia), at 6 months (n = 71) and at 18 months (n = 63). Body mass index, waist circumference at the lowest rib (WClowest rib) and iliac crest (WCiliac crest), fat mass, blood pressure, and biochemical data were collected at all 3 time points. Women’s BMI was higher at baseline (least square means (LSM) = 26.2 ± SE = 1.56 kg·m–2, p = 0.0004) and 6 months (25.9 ± 1.6, p = 0.0024) than at 18 months (22.1 ± 1.72). Men’s WClowest ribincreased from baseline (92.1 ± 1.87 cm) to 18 months (93.6 ± 1.87, p = 0.0253). Women who were active vs. inactive at baseline had a lower BMI at 6 months (23.1 ± 2.91 vs. 29.7 ± 2.52, p = 0.0957) and WCiliac crestat 6 months (82.8 ± 6.59 vs. 97.7 ± 5.10, p = 0.0818). Women who were active vs. inactive at 6 months had a lower WCiliac crestat 18 months (73.4 ± 14.3 vs. 102.5 ± 6.41, p = 0.0723). There was little change in traditional risk factors over 18 months. Future studies should extend beyond 18 months in a larger sample, and explore traditional vs. novel risk factors and onset of cardiovascular disease and diabetes in the SCI population.

International spinal cord injury musculoskeletal basic data set

OBJECTIVES

To develop an International Spinal Cord Injury (SCI) Musculoskeletal Basic Data Set as part of the International SCI Data Sets to facilitate consistent collection and reporting of basic musculoskeletal findings in the SCI population.

SETTING

International.

METHODS

A first draft of an SCI Musculoskeletal Basic Data Set was developed by an international working group. This was reviewed by many different organizations, societies and individuals over 9 months. Revised versions were created successively.

RESULTS

The final version of the International SCI Musculoskeletal Basic Data Set contains questions on neuro-musculoskeletal history before spinal cord lesion; presence of spasticity/spasms; treatment for spasticity within the last 4 weeks; fracture(s) since the spinal cord lesion; heterotopic ossification; contracture; the location of degenerative neuromuscular and skeletal changes due to overuse after SCI; SCI-related neuromuscular scoliosis; the method(s) used to determine the presence of neuromuscular scoliosis; surgical treatment of the scoliosis; other musculoskeletal problems; if any of the musculoskeletal challenges above interfere with activities of daily living. Instructions for data collection and the data collection form are freely available on the International Spinal Cord Society (ISCoS) website (www.iscos.org.uk).

CONCLUSION

The International SCI Musculoskeletal Basic Data Set will facilitate consistent collection and reporting of basic musculoskeletal findings in the SCI population.

Alterations in mouse hypothalamic adipokine gene expression and leptin signaling following chronic spinal cord injury and with advanced age

Chronic spinal cord injury (SCI) results in an accelerated trajectory of several cardiovascular disease (CVD) risk factors and related aging characteristics, however the molecular mechanisms that are activated have not been explored. Adipokines and leptin signaling are known to play a critical role in neuro-endocrine regulation of energy metabolism, and are now implicated in central inflammatory processes associated with CVD. Here, we examine hypothalamic adipokine gene expression and leptin signaling in response to chronic spinal cord injury and with advanced age. We demonstrate significant changes in fasting-induced adipose factor (FIAF), resistin (Rstn), long-form leptin receptor (LepRb) and suppressor of cytokine-3 (SOCS3) gene expression following chronic SCI and with advanced age. LepRb and Jak2/stat3 signaling is significantly decreased and the leptin signaling inhibitor SOCS3 is significantly elevated with chronic SCI and advanced age. In addition, we investigate endoplasmic reticulum (ER) stress and activation of the uncoupled protein response (UPR) as a biological hallmark of leptin resistance. We observe the activation of the ER stress/UPR proteins IRE1, PERK, and eIF2alpha, demonstrating leptin resistance in chronic SCI and with advanced age. These findings provide evidence for adipokine-mediated inflammatory responses and leptin resistance as contributing to neuro-endocrine dysfunction and CVD risk following SCI and with advanced age. Understanding the underlying mechanisms contributing to SCI and age related CVD may provide insight that will help direct specific therapeutic interventions.

An evidence-based review on the influence of aging with a spinal cord injury on subjective quality of life

STUDY DESIGN

Systematic review.

OBJECTIVES

To identify changes in subjective quality of life (QoL) as one ages with a spinal cord injury (SCI).

SETTING

Vancouver, Canada.

METHODS

Electronic databases were searched for studies reporting on age-related QoL changes over time. Data from relevant studies were transcribed into data extraction forms and analyzed by years post injury (YPI) and chronologic age. Each study was assigned a level of evidence based on a modified Sackett scale.

RESULTS

In all, 21 studies, each with a low level of evidence, were included for review. The results indicated that regardless of chronologic age, individuals with relatively new SCI have the potential to improve their QoL. Among individuals with advanced YPI, overall QoL is consistently reported as good or excellent over time, however, with variations in different QoL domains.

CONCLUSION

The QoL of individuals aging with a SCI has the potential to improve, and remain high and stable over time. As the identified studies provide low levels of evidence, more longitudinal research with greater methodological and measurement rigor is needed to corroborate the findings and conclusions of this review.

Spinal cord injury and physical activity: preservation of the body

SETTING

Spinal cord injury (SCI) causes devastating loss of function and can result in serious secondary complications. Although significant advances are being made to develop cellular and molecular therapies to promote regeneration, it is important to optimize physical interventions.

OBJECTIVES

The objective of this review was to examine the evidence for the effects of physical rehabilitation strategies on health and fitness, and maintenance of target systems below the level of injury (for example, muscle, bone, circulation).

RESULTS

Exercise appears to be a potent means of achieving these goals, using a variety of strategies.

CONCLUSION

Physical rehabilitation after SCI needs to move beyond the goal of maximizing independence to focus on maintenance of optimum health and fitness as well as maintenance of target system function below the level of injury. Issues requiring further investigation include identification of the optimum dosage of interventions to achieve specific goals, for example, prevention of muscle atrophy and osteoporosis, and development and validation of simple clinical measures to monitor the changes in body composition. Adoption of a classification system for physical interventions and standardized outcome measures would facilitate large-scale observational studies to identify the critical variables contributing to better outcomes.