Testosterone levels among men with spinal cord injury: relationship between time since injury and laboratory values

Evaluating Sex Steroid Hormone Neuroprotection in Spinal Cord Injury in Animal Models: Is It Promising in the Clinic?

The primary mechanism of traumatic spinal cord injury (SCI) comprises the initial mechanical trauma due to the transmission of energy to the spinal cord, subsequent deformity, and persistent compression. The secondary mechanism of injury, which involves structures that remained undamaged after the initial trauma, triggers alterations in microvascular perfusion, the liberation of free radicals and neurotransmitters, lipid peroxidation, alteration in ionic concentrations, and the consequent cell death by necrosis and apoptosis. Research in the treatment of SCI has sought to develop early therapeutic interventions that mitigate the effects of these pathophysiological mechanisms. Clinical and experimental evidence has demonstrated the therapeutic benefits of sex-steroid hormone administration after traumatic brain injury and SCI. The administration of estradiol, progesterone, and testosterone has been associated with neuroprotective effects, better neurological recovery, and decreased mortality after SCI. This review evaluated evidence supporting hormone-related neuroprotection over SCI and the possible underlying mechanisms in animal models. As neuroprotection has been associated with signaling pathways, the effects of these hormones are observed on astrocytes and microglia, modulating the inflammatory response, cerebral blood flow, and metabolism, mediating glutamate excitotoxicity, and their antioxidant effects. Based on the current evidence, it is essential to analyze the benefit of sex steroid hormone therapy in the clinical management of patients with SCI.

Sex hormone supplementation improves breathing and restores respiratory neuroplasticity following C2 hemisection in rats

In addition to loss of sensory and motor function below the level of the lesion, traumatic spinal cord injury (SCI) may reduce circulating steroid hormones that are necessary for maintaining normal physiological function for extended time periods. For men, who comprise nearly 80% of new SCI cases each year, testosterone is the most abundant circulating sex steroid. SCI often results in significantly reduced testosterone production and may result in chronic low testosterone levels. Testosterone plays a role in respiratory function and the expression of respiratory neuroplasticity. When testosterone levels are low, young adult male rats are unable to express phrenic long-term facilitation (pLTF), an inducible form of respiratory neuroplasticity invoked by acute, intermittent hypoxia (AIH). However, testosterone replacement can restore this respiratory neuroplasticity. Complicating the interpretation of this finding is that testosterone may exert its influence in three possible ways: 1) directly through androgen receptor (AR) activation, 2) through conversion to dihydrotestosterone (DHT) by way of the enzyme 5α-reductase, or 3) through conversion to 17β-estradiol (E2) by way of the enzyme aromatase. DHT signals via AR activation similar to testosterone, but with higher affinity, while E2 activates local estrogen receptors. Evidence to date supports the idea that exogenous testosterone supplementation exerts its influence through estrogen receptor signaling under conditions of low circulating testosterone. Here we explored both recovery of breathing function (measured with whole body barometric plethysmography) and the expression of AIH-induced pLTF in male rats following C2-hemisection SCI. One week post injury, rats were supplemented with either E2 or DHT for 7 days. We hypothesized that E2 would enhance ventilation and reveal pLTF following AIH in SCI rats. To our surprise, though E2 did beneficially impact overall breathing recovery following C2-hemisection, both E2 supplementation and DHT restored the expression of AIH-induced pLTF 2 weeks post-SCI.

A comprehensive look at the psychoneuroimmunoendocrinology of spinal cord injury and its progression: mechanisms and clinical opportunities

Spinal cord injury (SCI) is a devastating and disabling medical condition generally caused by a traumatic event (primary injury). This initial trauma is accompanied by a set of biological mechanisms directed to ameliorate neural damage but also exacerbate initial damage (secondary injury). The alterations that occur in the spinal cord have not only local but also systemic consequences and virtually all organs and tissues of the body incur important changes after SCI, explaining the progression and detrimental consequences related to this condition. Psychoneuroimmunoendocrinology (PNIE) is a growing area of research aiming to integrate and explore the interactions among the different systems that compose the human organism, considering the mind and the body as a whole. The initial traumatic event and the consequent neurological disruption trigger immune, endocrine, and multisystem dysfunction, which in turn affect the patient's psyche and well-being. In the present review, we will explore the most important local and systemic consequences of SCI from a PNIE perspective, defining the changes occurring in each system and how all these mechanisms are interconnected. Finally, potential clinical approaches derived from this knowledge will also be collectively presented with the aim to develop integrative therapies to maximize the clinical management of these patients.

Reversal of cold intolerance by testosterone in orchiectomized mice after tibial nerve transection

Cold intolerance is a debilitating effect of nerve injury, has a strong impact on the life of patients and no advisable treatment exists against it. Testosterone influences pain pathways and has analgesic effects. A recent study showed testosterone as being an agonist of TRPM8, the predominant ion channel that contributes to cold hypersensitivity after injury. We investigated the effect of testosterone on cold sensitivity after nerve injury. Specifically, using the double plate test (DPT) (thermo-neutral-plate: 31 ºC and cold-plate: 18 ºC) we determined the thermal preference of mice at different points during the study design consisting of: orchiectomy, tibial nerve transection (TNT) (30 days after orchiectomy), 15-days-repeated subcutaneous injections of testosterone enanthate (250 or 500 µg/kg/day) or vehicle (started 12 h after TNT surgery). Different parameters such as time spent on cold plates, distance traveled, animal speed on the cold- and thermo-neutral-plates were determined in naïve, sham and neuropathic animals. Neither orchiectomy nor sham TNT surgery generate effects on cold intolerance and animal activity while TNT surgery decreased the time spent on the cold-plate and the distance traveled during DPT. Testosterone administration reversed the effect of nerve injury, decreasing the cold hypersensitivity and increasing activity of TNT mice. However, the effect of testosterone on cold avoidance reduced with time and at 14 days after TNT surgery, a higher dose was needed to reverse the effect generated by nerve injury. This indicates that although testosterone administration has a positive effect on cold intolerance, it might not be suitable for prolongated treatment.

A Systematic Review of Testosterone Therapy in Men With Spinal Cord Injury or Traumatic Brain Injury

Spinal cord injuries (SCI) and traumatic brain injuries (TBI) increase the risk of testosterone deficiency and result in adverse changes in body composition and poor functional outcomes. The current systematic review aims to provide insights into the use of testosterone therapy for treating men with SCI and TBI. The PubMed and EMBASE databases were systematically reviewed using appropriate terms, and resulting manuscripts were screened using defined Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. The patient population included male patients with SCI or TBI. Further inclusion criteria were: a) human participants 18 years of age or older; b) manuscript published in English; c) study included an intervention with exogenous testosterone; and d) articles published in peer-reviewed journals with full text available. Two reviewers independently extracted data regarding injury type, intervention, and outcomes. Following screening for inclusion/exclusion criteria, a total of 12 primary research studies conducted over the last 30 years were included. Men with SCI were investigated in 11 articles. The combination of testosterone patches and resistance training with functional electrical stimulation (FES) for 16 weeks in men with SCI and an average baseline testosterone level above the cutoff for testosterone deficiency increased muscle mass, strength, bone quality, and basal metabolic rate while testosterone patches without exercise for 16 weeks produced no significant changes in these parameters. Testosterone patches for 12 months in men with SCI and testosterone deficiency also increased lean tissue mass (LTM) and resting energy expenditure (REE). In one study, men with TBI and testosterone deficiency receiving testosterone gel for eight weeks showed a non-statistically significant greater absolute change in functional independence measure (FIM) and grip strength compared to a placebo group. Testosterone therapy with exercise may help improve muscle mass, bone health, strength, energy expenditure, and cardiac health in men with SCI without major side effects. It is difficult to draw conclusions regarding the effects of testosterone therapy in men with TBI based on the limited available evidence. Further investigation is warranted to explore the relationship between testosterone therapy and recovery after SCI and TBI.

Early Changes in Androgen Levels in Individuals with Spinal Cord Injury: A Longitudinal SwiSCI Study

We aimed to explore longitudinal changes in androgen levels in individuals with spinal cord injury (SCI) within initial inpatient rehabilitation stay and identify clinical/injury characteristics associated with hormone levels. Linear regression analysis was applied to explore the association between personal/injury characteristics and androgen hormones (total testosterone, free testosterone, sex hormone-binding globulin (SHBG), dehydroepiandrosterone (DHEA), and dehydroepiandrosterone sulfate (DHEA-S)) at admission to rehabilitation. Longitudinal changes in androgen levels were studied using linear mixed models. Analyses were stratified by sex and by injury type. We included 70 men and 16 women with SCI. We observed a non-linear association between age, time since injury, and androgens at baseline. At admission to initial rehabilitation, mature serum SHBG (full-length, protein form which lacks the N-terminal signaling peptide) was higher, while DHEA and DHEA-S were lower among opioid users vs. non-users. Serum levels of total testosterone and DHEA-S increased over rehabilitation period [β 3.96 (95%CI 1.37, 6.56), p = 0.003] and [β 1.77 (95%CI 0.73, 2.81), p = 0.01], respectively. We observed no significant changes in other androgens. Restricting our analysis to men with traumatic injury did not materially change our findings. During first inpatient rehabilitation over a median follow up of 5.6 months, we observed an increase in total testosterone and DHEA-S in men with SCI. Future studies need to explore whether these hormonal changes influence neurological and functional recovery as well as metabolic parameters during initial rehabilitation stay.

Endocrinological and inflammatory markers in individuals with spinal cord injury: A systematic review and meta-analysis

Spinal cord injury (SCI) can lead to dramatic physiological changes which can be a factor in developing secondary health conditions and might be reflected in biomarker changes in this elevated risk group. We focused specifically on the endocrine and inflammation profile differences between SCI and able-bodied individuals (ABI). Our aim was to determine the differences in inflammatory markers and endocrine profiles between SCI and ABI. We systematically searched 4 electronic databases for relevant studies. Human observational (cross-sectional, cohort, case-control) studies that compared biomarkers of interest between SCI and ABI population were included. Weighted mean difference between SCI and ABI was calculated using random-effects models. Heterogeneity was computed using I² statistic and chi-squared test. Study quality was evaluated through the Newcastle-Ottawa Scale. The search strategy yielded a total of 2,603 studies from which 256 articles were selected for full-text assessment. Sixty-two studies were included in the meta-analysis. SCI individuals had higher levels of pro-inflammatory C-reactive protein and IL-6 than ABI. Creatinine and 25-hydroxyvitamin D₃ levels were lower in SCI than ABI. Total testosterone levels and IGF-1 were also found to be lower, while cortisol and leptin levels were higher in SCI when compared to ABI. Accordingly, meta-regression, subgroup analysis, and leave-one-out analysis were performed, however, they were only able to partially explain the high levels of heterogeneity. Individuals with SCI show higher levels of inflammatory markers and present significant endocrinological changes when compared to ABI. Moreover, higher incidence of obesity, diabetes, osteoporosis, and hypogonadism in SCI individuals, together with decreased creatinine levels reflect some of the readily measurable aspects of the phenotype changes in the SCI group. These findings need to be considered in anticipating medically related complications and personalizing SCI medical care.

Energy expenditure and nutrient intake after spinal cord injury: a comprehensive review and practical recommendations

Many persons with spinal cord injury (SCI) have one or more preventable chronic diseases related to excessive energetic intake and poor eating patterns. Appropriate nutrient consumption relative to need becomes a concern despite authoritative dietary recommendations from around the world. These recommendations were developed for the non-disabled population and do not account for the injury-induced changes in body composition, hypometabolic rate, hormonal dysregulation and nutrition status after SCI. Because evidence-based dietary reference intake values for SCI do not exist, ensuring appropriate consumption of macronutrient and micronutrients for their energy requirements becomes a challenge. In this compressive review, we briefly evaluate aspects of energy balance and appetite control relative to SCI. We report on the evidence regarding energy expenditure, nutrient intake and their relationship after SCI. We compare these data with several established nutritional guidelines from American Heart Association, Australian Dietary Guidelines, Dietary Guidelines for Americans, Institute of Medicine Dietary Reference Intake, Public Health England Government Dietary Recommendations, WHO Healthy Diet and the Paralyzed Veterans of America (PVA) Clinical Practice Guidelines. We also provide practical assessment and nutritional recommendations to facilitate a healthy dietary pattern after SCI. Because of a lack of strong SCI research, there are currently limited dietary recommendations outside of the PVA guidelines that capture the unique nutrient needs after SCI. Future multicentre clinical trials are needed to develop comprehensive, evidence-based dietary reference values specific for persons with SCI across the care continuum that rely on accurate, individual assessment of energy need.

Total Testosterone and Cortisol During Wheelchair Rugby Training in Athletes With Cervical Spinal Cord Injury

CONTEXT

Hormonal assessment in the sport context is important to monitor the physiological adaptations of athletes. However, Paralympic athletes, especially with cervical spinal cord injury (CSCI), may have different hormonal responses than nondisabled athletes. Therefore, the aim of this study was to evaluate the blood concentrations of total testosterone (TT) and cortisol (C) during acute (one training session) and chronic (1 and 2 month) training of athletes with CSCI in wheelchair rugby (WCR).

DESIGN

Longitudinal and observational study.

METHODS

Eight high-performance athletes with CSCI (31 [3.9] y; 75.6 [15.8] kg; 22.9 [4.2] kg/m2 body mass index; 6.2 [2] y of experience in sport) were evaluated at 3 different intervals (evaluations 1, 2, and 3 [E1, E2, and E3]) over 2 months of training. TT and C blood were evaluated before (pre) and after (post) the training sessions at each training moment, as well as the training load through the ratings of perceived exertion.

RESULTS

Athletes with CSCI had low TT concentrations. In acute training sessions, at E3, C decreases after the training session, unlike the TT/C ratio, which increased after the session. Regarding hormonal changes during chronic training at the end of the training period, unlike C, which increased. The training load (arbitrary units) decreased in E3 when compared with the other evaluation moments.

CONCLUSION

It was concluded that in chronic training, TT concentrations decreased, while C increased at the end of the 2 months of training. These results may indicate that training volume was high throughout training and that a reduction in training volume could benefit athletes. On the other hand, in the acute training session with reduced training load, a decrease in C was observed after the training session. This indicates that athletes may be well recovered in this training session. Therefore, we suggest acute and long-term hormonal assessment for athletes with CSCI as a strategy to monitor anabolic/catabolic hormonal status during WCR training.

Visceral Adiposity, Inflammation, and Testosterone Predict Skeletal Muscle Mitochondrial Mass and Activity in Chronic Spinal Cord Injury

Background

Mitochondrial health is an important predictor of several health-related comorbidities including obesity, type 2 diabetes mellitus, and cardiovascular disease. In persons with spinal cord injury (SCI), mitochondrial health has been linked to several important body composition and metabolic parameters. However, the complex interplay of how mitochondrial health is affected has yet to be determined in this population.

Objective

In this study, we examined the contribution of visceral adiposity, inflammatory biomarkers, testosterone and circulating serum growth factors as predictors of mitochondrial health in persons with chronic SCI.

Participants

Thirty-three individuals with chronic SCI (n = 27 Males, n = 6 Females, age: 40 ± 13.26 years, level of injury: C4-L1, BMI: 23 ± 5.57) participated in this cross-sectional study.

Methods

Visceral adipose tissue (VAT) was measured via magnetic resonance imaging (MRI). After an overnight fast, serum testosterone, inflammatory biomarkers [interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), c-reactive protein (CRP)], and anabolic growth factors [insulin-like growth factor 1 (IGF-1), insulin-like growth factor binding protein 3 (IGFBP-3)] were measured. Skeletal muscle biopsies were obtained from the vastus lateralis muscle to measure citrate synthase (CS) and Complex III activity. Regression analyses were used to examine predictors of mitochondrial mass and activity.

Results

CS activity was negatively associated with VAT (r² = 0.360, p < 0.001), CRP (r² = 0.168, p = 0.047), and positively associated with testosterone (r² = 0.145, p = 0.042). Complex III activity was negatively associated with VAT relative to total lean mass (VAT:TLM) (r² = 0.169, p = 0.033), trended for CRP (r² = 0.142, p = 0.069), and positively associated with testosterone (r² = 0.224, p = 0.010). Multiple regression showed CS activity was significantly associated with VAT + CRP (r² = 0.412, p = 0.008) and VAT + Testosterone (r² = 0.433, p = 0.001). Complex III activity was significantly associated with VAT relative to total trunk cross-sectional area (CSA) + CRP (VAT:total trunk CSA + CRP; r² = 0.286, p = 0.048) and VAT + Testosterone (r² = 0.277, p = 0.024).

Conclusion

Increased visceral adiposity and associated inflammatory signaling (CRP) along with reduced testosterone levels predict mitochondrial dysfunction following SCI. Specifically, lower VAT_CSA and higher testosterone levels or lower VAT_CSA and lower CRP levels positively predict mitochondrial mass and enzyme activity in persons with chronic SCI. Future research should investigate the efficacy of diet, exercise, and potentially testosterone replacement therapy on enhancing mitochondrial health in chronic SCI.

Clinical Trial Registration

[www.ClinicalTrials.gov], identifier: [NCT02660073].

Men with spinal cord injury have a smaller prostate volume than age-matched able-bodied men: a meta-analysis of case-control studies

STUDY DESIGN

Meta-analysis OBJECTIVES: Denervation and androgen deficiency, peculiar to individuals with chronic spinal cord injury (SCI), could hinder, to some extent, both prostate growth and activity. To comprehensively assess the relationship between SCI and prostate volume, we carried out a meta-analysis of the available case-control studies.

METHODS

A thorough search of MEDLINE, Scopus and Web of Science was carried out to identify studies comparing prostate volume in men with and without SCI. Quality of the studies was assessed using the Newcastle-Ottawa Scale (NOS). Mean differences (MDs) in prostate volume were combined using a random effect model. Funnel plot was used to assess publication bias.

RESULTS

Four studies met the inclusion criteria and provided information on 278 men with SCI and 1385 able-bodied controls. The overall difference in prostate volume between the two groups reached the statistical significance (pooled MD: -14.85 ml, 95% CI: -27.10 to -2.61, p = 0.02). In a subgroup analysis including only the studies with the highest NOS score, the pooled MD remained significant (pooled MD: -18.56, 95% CI: -33.14 to -3.99, p = 0.01). The shape of funnel plot did not allow to rule out a possible publication bias.

CONCLUSIONS

This meta-analysis suggests that in men with SCI, prostate volume tends to be smaller than in age-matched able-bodied men. Longitudinal studies of men with long-lasting SCI in advanced age are warranted to clarify whether this condition is associated with a lower risk of age-related prostate proliferative diseases.

Role of exercise on visceral adiposity after spinal cord injury: a cardiometabolic risk factor

PURPOSE

Visceral adipose tissue (VAT) is associated with cardiometabolic disease risk in able-bodied (AB) populations. However, the underlying mechanisms of VAT-induced disease risk are unknown in persons with spinal cord injury (SCI). Potential mechanisms of VAT-induced cardiometabolic dysfunction in persons with SCI include systemic inflammation, liver adiposity, mitochondrial dysfunction, and anabolic deficiency. Moreover, how exercise interventions impact these mechanisms associated with VAT-induced cardiometabolic dysfunction are still being explored.

METHODS

A search for relevant scientific literature about the effects of exercise on VAT and cardiometabolic health was conducted on the PubMed database. Literature from reference lists was also included when appropriate.

RESULTS

Both aerobic and resistance exercise training beneficially impact health and VAT mass via improving mitochondrial function, glucose effectiveness, and inflammatory signaling in SCI and AB populations. Specifically, aerobic exercise appears to also modulate cellular senescence in AB populations and animal models, while resistance exercise seems to augment anabolic signaling in persons with SCI.

CONCLUSIONS

The current evidence supports regular engagement in exercise to reduce VAT mass and the adverse effects on cardiometabolic health in persons with SCI. Future research is needed to further elucidate the precise mechanisms by which VAT negatively impacts health following SCI. This will likely facilitate the development of rehabilitation protocols that target VAT reduction in persons with SCI.

Neurogenic Obesity and Skeletal Pathology in Spinal Cord Injury

Spinal cord injury (SCI) results in dramatic changes in body composition, with lean mass decreasing and fat mass increasing in specific regions that have important cardiometabolic implications. Accordingly, the recent Consortium for Spinal Cord Medicine (CSCM) released clinical practice guidelines for cardiometabolic disease (CMD) in SCI recommending the use of compartmental modeling of body composition to determine obesity in adults with SCI. This recommendation is guided by the fact that fat depots impact metabolic health differently, and in SCI adiposity increases around the viscera, skeletal muscle, and bone marrow. The contribution of skeletal muscle atrophy to decreased lean mass is self-evident, but the profound loss of bone is often less appreciated due to methodological considerations. General-population protocols for dual-energy x-ray absorptiometry (DXA) disregard assessment of the sites of greatest bone loss in SCI, but the International Society for Clinical Densitometry (ISCD) recently released an official position on the use of DXA to diagnose skeletal pathology in SCI. In this review, we discuss the recent guidelines regarding the evaluation and monitoring of obesity and bone loss in SCI. Then we consider the possible interactions of obesity and bone, including emerging evidence suggesting the possible influence of metabolic, autonomic, and endocrine function on bone health in SCI.

Pathophysiology of Neurogenic Obesity After Spinal Cord Injury

Individuals with a spinal cord injury (SCI) have a unique physiology characterized by sarcopenia, neurogenic osteoporosis, neurogenic anabolic deficiency, sympathetic dysfunction, and blunted satiety associated with their SCI, all of which alter energy balance and subsequently body composition. The distinct properties of "neurogenic obesity" place this population at great risk for metabolic dysfunction, including systemic inflammation, hyperglycemia, dyslipidemia, and hypertension. The purpose of this article is to demonstrate the relationship between neurogenic obesity and the metabolic syndrome after SCI, highlighting the mechanisms associated with adipose tissue pathology and those respective comorbidities. Additionally, representative studies of persons with SCI will be provided to elucidate the severity of the problem and to prompt greater vigilance among SCI specialists as well as primary care providers in order to better manage the epidemic from a public health perspective.

Development of a quantitative method for determination of steroids in human plasma by gas chromatography-negative chemical ionization-tandem mass spectrometry

Sex steroids are involved in biological functions that encompass from the complete sexual development of individuals up to the deregulation of metabolic pathways leading to some pathologies. Steroids are present in blood at low concentration levels from pg mL^-1 to ng mL^-1. For this reason, a high sensitive and selective method based on gas chromatography-negative chemical ionization-tandem mass spectrometry (GC-NCI-MS/MS) is here proposed to quantify either androgens (androstenedione, dehydroepiandrosterone, dihydrotestosterone and testosterone), estrogens (estrone and estradiol) and a progestogen (progesterone) in human plasma. The sample preparation steps, protein precipitation and solid phase extraction, were optimized to ensure the sample matrix removal and to extract steroids with high efficiency. The NCI-MS/MS detection approach was compared with that based on electron impact to evaluate the incidence of the ionization source in the determination of steroids. The quantification limits for determination of these analytes were in a range from 10 pg mL^-1 to 5 ng mL^-1, with a high sensitivity for estrogens, typically found at low concentrations. The proposed method was tested for the determination of steroids in male blood samples, in which 6 out of 7 steroids were detected and quantified to report concentration values in agreement with those described in the literature.

Testosterone and Resistance Training Improve Muscle Quality in Spinal Cord Injury

PURPOSE

Spinal cord injury (SCI) negatively impacts muscle quality and testosterone levels. Resistance training (RT) has been shown to increase muscle cross-sectional area (CSA) after SCI, whereas testosterone replacement therapy (TRT) has been shown to improve muscle quality in other populations. The purpose of this pilot study was to examine if the combined effects of these interventions, TRT + RT, may maximize the beneficial effects on muscle quality after SCI.

METHODS

Twenty-two SCI subjects randomized into either a TRT + RT (n = 11) or TRT (n = 11) intervention for 16 wk. Muscle quality measured by peak torque (PT) at speeds of 0°·s (PT-0°), 60°·s (PT-60°), 90°·s (PT-90°), and 180°·s (PT-180°), knee extensor CSA, specific tension, and contractile speed (rise time [RTi], and half-time to relaxation [½TiR]) was assessed for each limb at baseline and postintervention using 2 × 2 mixed models.

RESULTS

After 16 wk, subjects in the TRT + RT group increased PT-0° (48.4%, P = 0.017), knee extensor CSA (30.8%, P < 0.0001), and RTi (17.7%, P = 0.012); with no significant changes observed in the TRT group. Regardless of the intervention, changes to PT-60° (28.4%, P = 0.020), PT-90° (26.1%, P = 0.055), and PT-180° (20.6%, P = 0.09) for each group were similar.

CONCLUSIONS

The addition of mechanical stress via RT to TRT maximizes improvements to muscle quality after complete SCI when compared with TRT administered alone. Our evidence shows that this intervention increases muscle size and strength while also improving muscle contractile properties.

Lifestyle modifications and pharmacological approaches to improve sexual function and satisfaction in men with spinal cord injury: a narrative review

STUDY DESIGN

A narrative review describing various components of sexual dysfunction in men with spinal cord injury (SCI), as well as addressing potential therapeutic approaches.

OBJECTIVES

Restoration of sexual function is considered one of the most important health priorities for individuals with SCI. The purpose of this review is to provide information regarding the factors that are less appreciated when considering changes to sexual function in men with SCI. We also propose therapeutic approaches, with a focus on lifestyle modifications, which have been shown to improve sexual function.

METHODS

A literature search was performed and limited evidence for therapeutic approaches in individuals with SCI was supplemented by consistent findings from the able-bodied population.

RESULTS

We evaluated the less addressed factors known to contribute to sexual dysfunction in men with SCI, including hormonal influences (i.e., testosterone deficiency, thyroid hormone, and cortisol), psychological factors (i.e., pain, fatigue, depression, and body image), and secondary SCI complications (i.e., urinary tract infection, pressure sores, and autonomic dysreflexia). To address these factors beyond standard medical treatments for sexual dysfunction, options include physical activity/exercise, diet, and specific medications for symptom relief (i.e., testosterone replacement therapy and selective serotonin reuptake inhibitors for depression).

CONCLUSIONS

Physical activity's potential application, efficacy across multiple aspects of sexuality, and the lack of side effects, suggests that long-term exercise is a viable solution to directly or indirectly improve sexual function in males with SCI. Diet and supplemental medications may further promote body composition changes, which more broadly affect sexuality.

Locomotor training with adjuvant testosterone preserves cancellous bone and promotes muscle plasticity in male rats after severe spinal cord injury

Loading and testosterone may influence musculoskeletal recovery after spinal cord injury (SCI). Our objectives were to determine (a) the acute effects of bodyweight-supported treadmill training (TM) on hindlimb cancellous bone microstructure and muscle mass in adult rats after severe contusion SCI and (b) whether longer-term TM with adjuvant testosterone enanthate (TE) delivers musculoskeletal benefit. In Study 1, TM (40 min/day, 5 days/week, beginning 1 week postsurgery) did not prevent SCI-induced hindlimb cancellous bone loss after 3 weeks. In Study 2, TM did not attenuate SCI-induced plantar flexor muscles atrophy nor improve locomotor recovery after 4 weeks. In our main study, SCI produced extensive distal femur and proximal tibia cancellous bone deficits, a deleterious slow-to-fast fiber-type transition in soleus, lower muscle fiber cross-sectional area (fCSA), impaired muscle force production, and levator ani/bulbocavernosus (LABC) muscle atrophy after 8 weeks. TE alone (7.0 mg/week) suppressed bone resorption, attenuated cancellous bone loss, constrained the soleus fiber-type transition, and prevented LABC atrophy. In comparison, TE+TM concomitantly suppressed bone resorption and stimulated bone formation after SCI, produced near-complete cancellous bone preservation, prevented the soleus fiber-type transition, attenuated soleus fCSA atrophy, maintained soleus force production, and increased LABC mass. 75% of SCI+TE+TM animals recovered voluntary over-ground hindlimb stepping, while no SCI and only 20% of SCI+TE animals regained stepping ability. Positive associations between testosterone and locomotor function suggest that TE influenced locomotor recovery. In conclusion, short-term TM alone did not improve bone, muscle, or locomotor recovery in adult rats after severe SCI, while longer-term TE+TM provided more comprehensive musculoskeletal benefit than TE alone.

Low-Dose Testosterone and Evoked Resistance Exercise after Spinal Cord Injury on Cardio-Metabolic Risk Factors: An Open-Label Randomized Clinical Trial

The purpose of the work is to investigate the effects of low-dose testosterone replacement therapy (TRT) and evoked resistance training (RT) on body composition and metabolic variables after spinal cord injury (SCI). Twenty-two individuals with chronic motor complete SCI (ages 18-50 years) were randomly assigned to either TRT+RT (n = 11) or TRT (n = 11) for 16 weeks following a 4 -week delayed entry period. TRT+RT men underwent twice weekly progressive RT using electrical stimulation with ankle weights. TRT was administered via testosterone patches (2-6 mg/day). Body composition was tested using anthropometrics, dual energy x-ray absorptiometry, and magnetic resonance imaging. After an overnight fast, basal metabolic rate (BMR), lipid panel, serum testosterone, adiponectin, inflammatory and anabolic biomarkers (insulin-like growth factor-1 and insulin-like growth factor-binding protein 3 [IGFBP-3]), glucose effectiveness (Sg), and insulin sensitivity (Si) were measured. Total body lean mass (LM; 2.7 kg, p < 0.0001), whole muscle (p < 0.0001), and whole muscle knee extensor cross-sectional areas (CSAs; p < 0.0001) increased in the TRT+RT group, with no changes in the TRT group. Visceral adiposity decreased (p = 0.049) in the TRT group, with a trend in the TRT+RT (p = 0.07) group. There was a trend (p = 0.050) of a 14-17% increase in BMR following TRT+RT. Sg showed a trend (p = 0.07) to improvement by 28.5-31.5% following both interventions. IGFBP-3 increased (p = 0.0001) while IL-6 decreased (p = 0.039) following both interventions, and TRT+RT suppressed adiponectin (p = 0.024). TRT+RT resulted in an increase in LM and whole thigh and knee extensor muscle CSAs, with an increase in BMR and suppressed adiponectin. Low-dose TRT may mediate modest effects on visceral adipose tissue, Sg, IGFBP-3, and IL-6, independent of changes in LM.

Body composition changes with testosterone replacement therapy following spinal cord injury and aging: A mini review

Context Hypogonadism is a male clinical condition in which the body does not produce enough testosterone. Testosterone plays a key role in maintaining body composition, bone mineral density, sexual function, mood, erythropoiesis, cognition and quality of life. Hypogonadism can occur due to several underlying pathologies during aging and in men with physical disabilities, such as spinal cord injury (SCI). This condition is often under diagnosed and as a result, symptoms undertreated. Methods In this mini-review, we propose that testosterone replacement therapy (TRT) may be a viable strategy to improve lean body mass (LBM) and fat mass (FM) in men with SCI. Evidence Synthesis Supplementing the limited data from SCI cohorts with consistent findings from studies in non-disabled aging men, we present evidence that, relative to placebo, transdermal TRT can increase LBM and reduce FM over 3-36 months. The impact of TRT on bone mineral density and metabolism is also discussed, with particular relevance for persons with SCI. Moreover, the risks of TRT remain controversial and pertinent safety considerations related to transdermal administration are outlined. Conclusion Further research is necessary to help develop clinical guidelines for the specific dose and duration of TRT in persons with SCI. Therefore, we call for more high-quality randomized controlled trials to examine the efficacy and safety of TRT in this population, which experiences an increased risk of cardiometabolic diseases as a result of deleterious body composition changes after injury.

Activity-Based Physical Rehabilitation with Adjuvant Testosterone to Promote Neuromuscular Recovery after Spinal Cord Injury

Neuromuscular impairment and reduced musculoskeletal integrity are hallmarks of spinal cord injury (SCI) that hinder locomotor recovery. These impairments are precipitated by the neurological insult and resulting disuse, which has stimulated interest in activity-based physical rehabilitation therapies (ABTs) that promote neuromuscular plasticity after SCI. However, ABT efficacy declines as SCI severity increases. Additionally, many men with SCI exhibit low testosterone, which may exacerbate neuromusculoskeletal impairment. Incorporating testosterone adjuvant to ABTs may improve musculoskeletal recovery and neuroplasticity because androgens attenuate muscle loss and the slow-to-fast muscle fiber-type transition after SCI, in a manner independent from mechanical strain, and promote motoneuron survival. These neuromusculoskeletal benefits are promising, although testosterone alone produces only limited functional improvement in rodent SCI models. In this review, we discuss the (1) molecular deficits underlying muscle loss after SCI; (2) independent influences of testosterone and locomotor training on neuromuscular function and musculoskeletal integrity post-SCI; (3) hormonal and molecular mechanisms underlying the therapeutic efficacy of these strategies; and (4) evidence supporting a multimodal strategy involving ABT with adjuvant testosterone, as a potential means to promote more comprehensive neuromusculoskeletal recovery than either strategy alone.

Relationship Between Gonadal Function and Cardiometabolic Risk in Young Men With Chronic Spinal Cord Injury

BACKGROUND

We reported previously that young men with chronic spinal cord injury (SCI) have a greater prevalence of testosterone deficiency compared with an age-matched, healthy control population. Young men with SCI also are at increased risk for developing cardiometabolic dysfunction after injury. It is unclear whether testosterone deficiency is associated with heightened cardiometabolic risk in men with SCI.

OBJECTIVE

To investigate associations among levels of testosterone in young men with chronic SCI and surrogate markers of cardiometabolic risk.

DESIGN

Secondary cross-sectional analysis.

SETTING

Rehabilitation research centers in Washington, DC, and Miami, Florida.

PARTICIPANTS

Men (n = 58) aged 18-45 years with chronic (≥1 year), motor complete SCI without comorbidities or use of testosterone therapy.

METHODS

Plasma concentrations of testosterone, lipids, inflammatory markers (C-reactive protein and interleukin-6), percent hemoglobin A1c, glucose, and insulin were measured in a fasting state using standard assays. A 2-hour oral glucose tolerance test and Framingham Risk Score were assessed for each subject. Body composition was assessed by dual X-ray absorptiometry scan.

MAIN OUTCOME MEASUREMENTS

Surrogate markers of cardiometabolic risk among men based on the level of total testosterone (TT; ≤300, 301-500, or >500 ng/dL) and free testosterone (fT; ≤9 or >9 ng/dL). Comparisons were made between men with normal and low TT or fT.

RESULTS

Framingham Risk Score was significantly greater in men with low fT (P < .05). Percent body fat (P < .05) and waist-to-hip ratio (P < .05) but not body mass index (P > .08), were greater in men with low TT or low fT. Men with low TT or low fT had lower high-density lipoprotein cholesterol levels (P < .05) without differences in fasting triglycerides (P > .1) or low-density lipoprotein cholesterol (P > .07). Men with low TT had greater levels of inflammatory markers C-reactive protein (P < .05) and interleukin-6 (P < .05). Men with low TT or low fT had greater fasting glucose (P < .05) and greater insulin resistance (P < .04), without differences in percent hemoglobin A1c (P > .8).

CONCLUSIONS

In young men with chronic SCI who undergo an accelerated aging process postinjury, hypogonadism is associated with an unfavorable cardiometabolic risk profile. Further research is needed to determine whether a causal relationship exists between hypogonadism and heightened cardiometabolic risk in men with SCI and whether routine screening for testosterone deficiency is warranted in this population.

LEVEL OF EVIDENCE

IV.

Administration of increasing doses of gonadotropin-releasing hormone in men with spinal cord injury to investigate dysfunction of the hypothalamic-pituitary-gonadal axis

STUDY DESIGN

Prospective.

OBJECTIVES

To determine the optimum gonadotropin-releasing hormone (GnRH) dose to identify dysfunction of the hypothalamic-pituitary-gonadal axis in men with spinal cord injury (SCI).

SETTING

Metropolitan Area Hospitals, New York and New Jersey, USA.

METHODS

SCI men (16 hypogonadal (HG = serum testosterone <12.1 nmol/l) and 14 eugonadal (EG)) and able-bodied (AB) men (27 HG and 11 EG) were studied. GnRH (10, 50, and 100 μg) was randomly administered intravenously on three separate visits. Blood samples were collected post-GnRH for serum-luteinizing hormone (LH) and follicular-stimulating hormone (FSH).

RESULTS

HG and EG men had a similar proportion of clinically acceptable gonadotropin responses to all three GnRH doses. The incremental gonadotropin responses to GnRH were not significantly different across the groups. However, in the SCI-HG group, GnRH of 100 μg resulted in the greatest integrated FSH response, and in the SCI-EG group, GnRH of 50 μg resulted in the greatest integrated LH response compared with the AB groups. A consistent, but not significant, absolute increase in gonadotropin release was observed in the SCI groups at all GnRH doses.

CONCLUSIONS

Lower doses of GnRH did not improve the ability to identify the clinical dysfunction of the hypothalamic-pituitary-gonadal axis. However, the absolutely higher SCI-HG FSH response to GnRH of 100 μg and a higher SCI-EG LH response to GnRH of 50 μg, along with a higher gonadotropin release at all GnRH doses, albeit not significant, suggests a hypothalamic-pituitary dysfunction in persons with SCI.

Associations of the trunk skeletal musculature and dietary intake to biomarkers of cardiometabolic health after spinal cord injury

PURPOSE

Skeletal muscle atrophy and poor dietary habits may contribute to increased adiposity and impaired metabolic health after spinal cord injury (SCI). The relative association of trunk muscle cross-sectional areas (CSA) versus dietary habits to central adiposity and impaired metabolic health after SCI remains unclear.

METHODS

Twenty-two men with motor complete SCI completed five-day dietary recalls for 4 weeks. Trunk muscle CSAs as well as visceral and subcutaneous adipose tissue (VAT and SAT, respectively) were quantified using magnetic resonance imaging. Basal metabolic rate (BMR), glucose effectiveness, insulin sensitivity and lipid profile were measured after overnight fast.

RESULTS

Antero-lateral trunk muscle (r = -0·79, P < 0·001) and posterior trunk muscle (r = -0·56, P = 0·008) CSAs normalized to total trunk CSA were negatively related to VAT. Antero-lateral trunk muscle ratio (TMR) was positively related to BMR (r = 0·54, P = 0·01), and posterior TMR was positively related to peak oxygen uptake (VO2 peak; r = 0·71, P = 0·003). After accounting for total TMR as a co-variate, total fat (r = 0·47, P = 0·04) and protein (r = 0·61, P = 0·004) intakes were positively related to fasting insulin levels.

CONCLUSION

Trunk muscle CSAs normalized to total trunk CSA were negatively associated with central adiposity. Both trunk muscles and dietary macro-nutrients are related to markers of metabolic health. The study highlights the significance of developing an exercise intervention with a healthy dietary regimen to attenuate the development of central adiposity associated metabolic disorders after SCI.

Testicular responses to hCG stimulation at varying doses in men with spinal cord injury

STUDY DESIGN

Prospective.

OBJECTIVES

To test whether provocative stimulation of the testes identifies men with chronic spinal cord injury (SCI), a population in which serum testosterone concentrations are often depressed, possibly due to gonadal dysfunction. To accomplish this objective, conventional and lower than the conventional doses of human chorionic gonadotropin (hCG) were administered.

METHODS

Thirty men with chronic SCI (duration of injury >1 year; 18 and 65 years old; 16 eugonadal (>12.1 nmol l-1) and 14 hypogonadal (⩽12.1 nmol l-1)) or able-bodied (AB) men (11 eugonadal and 27 hypogonadal) were recruited for the study. Stimulation tests were performed to quantify testicular responses to the intramuscular administration of hCG at three dose concentrations (ithat is, 400, 2000 and 4000 IU). The hCG was administered on two consecutive days, and blood was collected for serum testosterone in the early morning prior to each of the two injections; subjects returned on day 3 for a final blood sample collection.

RESULTS

The average gonadal response in the SCI and AB groups to each dose of hCG was not significantly different in the hypogonadal or eugonadal subjects, with the mean serum testosterone concentrations in all groups demonstrating an adequate response.

CONCLUSIONS

This work confirmed the absence of primary testicular dysfunction without additional benefit demonstrated of provocative stimulation of the testes with lower than conventional doses of hCG. Our findings support prior work that suggested a secondary testicular dysfunction that occurs in a majority of those with SCI and depressed serum testosterone concentrations.

Effects of Testosterone and Evoked Resistance Exercise after Spinal Cord Injury (TEREX-SCI): study protocol for a randomised controlled trial

INTRODUCTION

Individuals with spinal cord injury (SCI) are at a lifelong risk of obesity and chronic metabolic disorders including insulin resistance and dyslipidemia. Within a few weeks of injury, there is a significant decline in whole body fat-free mass, particularly lower extremity skeletal muscle mass, and subsequent increase in fat mass (FM). This is accompanied by a decrease in anabolic hormones including testosterone. Testosterone replacement therapy (TRT) has been shown to increase skeletal muscle mass and improve metabolic profile. Additionally, resistance training (RT) has been shown to increase lean mass and reduce metabolic disturbances in SCI and other clinical populations.

METHODS AND ANALYSIS

26 individuals with chronic, motor complete SCI between 18 and 50 years old were randomly assigned to a RT+TRT group (n=13) or a TRT group (n=13). 22 participants completed the initial 16-week training phase of the study and 4 participants withdrew. 12 participants of the 22 completed 16 weeks of detraining. The TRT was provided via transdermal testosterone patches (4-6 mg/day). The RT+TRT group had 16 weeks of supervised unilateral progressive RT using surface neuromuscular electrical stimulation with ankle weights. This study will investigate the effects of evoked RT+TRT or TRT alone on body composition (muscle cross-sectional area, visceral adipose tissue, %FM) and metabolic profile (glucose and lipid metabolism) in individuals with motor complete SCI. Findings from this study may help in designing exercise therapies to alleviate the deterioration in body composition after SCI and decrease the incidence of metabolic disorders in this clinical population.

ETHICS AND DISSEMINATION

The study is currently approved by the McGuire VA Medical Center and Virginia Commonwealth University. All participants read and signed approved consent forms. Results will be submitted to peer-reviewed journals and presented at national and international conferences.

TRIAL REGISTRATION NUMBER

Pre-result, NCT01652040.

Serum Prolactin Levels in Multiple Sclerosis, Neuromyelitis Optica, and Clinically Isolated Syndrome Patients

INTRODUCTION

Prolactin has been discussed as a factor likely to play a mediating role in multiple sclerosis (MS). Our aim was to investigate the possible association between prolactin production and clinical features of autoimmune demyelinating central nervous system disorders.

METHODS

Serum prolactin levels of 255 MS patients, 19 neuromyelitis optica (NMO) patients, 15 clinically isolated syndrome (CIS) patients, and 240 healthy controls were measured by a heterogeneous sandwich magnetic separation assay.

RESULTS

MS and NMO cohorts had a significantly higher number of patients with hyperprolactinemia than healthy controls. Sera obtained during attacks of both MS and NMO patients displayed higher prolactin levels than those collected during remission. Prolactin level elevations were found to be more prominent in myelitis attacks in MS. No significant correlation was found between prolactin levels and age, disease duration, disability status, number of attacks, and oligoclonal band positivity. CIS patients who converted to MS had higher prolactin levels than those who did not.

CONCLUSION

Our findings support the possible mediating role of prolactin in the immunopathogenesis of MS, NMO, and conversion from CIS to MS.

Prevalence and Etiology of Hypogonadism in Young Men With Chronic Spinal Cord Injury: A Cross-Sectional Analysis From Two University-Based Rehabilitation Centers

BACKGROUND

Spinal cord injury (SCI) triggers an "accelerated aging" process that may include development of hypogonadism, even among younger men with SCI; however, few studies have investigated the prevalence or etiology of hypogonadism in men with SCI. Young men with SCI also are at increased risk for developing metabolic dysfunction after injury, which may be exacerbated by concomitant testosterone (T) deficiency, thus identifying the prevalence and risk factors for T deficiency in men with SCI is important for their long-term health.

OBJECTIVE

To investigate the prevalence, risk factors, and etiology of T deficiency (hypogonadism) in otherwise-healthy men with chronic, motor complete SCI.

DESIGN

Secondary cross-sectional analysis.

SETTING

Rehabilitation research centers in Washington, DC, and Miami, Florida.

PARTICIPANTS

Men (n = 58) aged 18-45 years with chronic (≥1 year), motor complete SCI without comorbidities or use of testosterone therapy.

METHODS

Plasma concentrations of hormones were measured with standardized assays. Body composition was assessed with dual-energy x-ray absorptiometry scan.

MAIN OUTCOME MEASUREMENTS

Serum total T and calculated free T.

RESULTS

T deficiency was more common in men after SCI than in a matched cohort of similarly-aged men without SCI (25%, SCI versus 6.7%, non-SCI, P < .001). The risk of hypogonadism appeared to be increased in men with more extensive injury and with higher percent body fat. The majority of men with SCI with low T had low serum LH levels, suggesting that central suppression of the hypothalamic-pituitary-gonadal axis may be the most common etiology of hypogonadism after SCI.

CONCLUSIONS

Hypogonadism is more common in young men with SCI than in similarly aged men without SCI, suggesting that SCI should be identified as a risk factor for T deficiency and that routine screening for hypogonadism should be performed in the SCI population.

LEVEL OF EVIDENCE

II.

Male fertility following spinal cord injury: an update

Spinal cord injury (SCI) occurs most often in young men at the peak of their reproductive health. The majority of men with SCI cannot father children naturally. Three major complications contribute to infertility in men with SCI: erectile dysfunction, ejaculatory dysfunction, and abnormal semen quality. Erectile dysfunction can be managed by regimens available to the general population, including oral administration of phosphodiesterase-5 (PDE-5) inhibitors, intracavernosal injections, vacuum devices, and penile prostheses. Semen may be obtained from anejaculatory men with SCI via the medically assisted ejaculation methods of penile vibratory stimulation (PVS) or electroejaculation (EEJ). Sperm retrieval is also possible via prostate massage or surgical sperm retrieval. Most men with SCI have abnormal semen quality characterized by normal sperm concentrations but abnormally low sperm motility and viability. Accessory gland dysfunction has been proposed as the cause of these abnormalities. Leukocytospermia is evident in most SCI patients. Additionally, elevated concentrations of pro-inflammatory cytokines and elevated concentrations of inflammasome components are found in their semen. Neutralization of these constituents has resulted in improved sperm motility. There is a recent and alarming trend in the management of infertility in couples with SCI male partners. Although many men with SCI have sufficient motile sperm in their ejaculates for attempting intrauterine insemination (IUI) or even intravaginal insemination, surgical sperm retrieval is often introduced as the first and only sperm retrieval method for these couples. Surgical sperm retrieval commits the couple to the most advanced, expensive, and invasive method of assisted conception: in vitro fertilization with intracytoplasmic sperm injection (IVF/ICSI). Couples should be informed of all options, including semen retrieval by PVS or EEJ. Intravaginal insemination or IUI should be considered when indicated.

Sclerostin inhibition prevents spinal cord injury-induced cancellous bone loss

Spinal cord injury (SCI) results in rapid and extensive sublesional bone loss. Sclerostin, an osteocyte-derived glycoprotein that negatively regulates intraskeletal Wnt signaling, is elevated after SCI and may represent a mechanism underlying this excessive bone loss. However, it remains unknown whether pharmacologic sclerostin inhibition ameliorates bone loss subsequent to SCI. Our primary purposes were to determine whether a sclerostin antibody (Scl-Ab) prevents hindlimb cancellous bone loss in a rodent SCI model and to compare the effects of a Scl-Ab to that of testosterone-enanthate (TE), an agent that we have previously shown prevents SCI-induced bone loss. Fifty-five (n = 11-19/group) skeletally mature male Sprague-Dawley rats were randomized to receive: (A) SHAM surgery (T8 laminectomy), (B) moderate-severe (250 kilodyne) SCI, (C) 250 kilodyne SCI + TE (7.0 mg/wk, im), or (D) 250 kilodyne SCI + Scl-Ab (25 mg/kg, twice weekly, sc) for 3 weeks. Twenty-one days post-injury, SCI animals exhibited reduced hindlimb cancellous bone volume at the proximal tibia (via μCT and histomorphometry) and distal femur (via μCT), characterized by reduced trabecular number and thickness. SCI also reduced trabecular connectivity and platelike trabecular structures, indicating diminished structural integrity of the remaining cancellous network, and produced deficits in cortical bone (femoral diaphysis) strength. Scl-Ab and TE both prevented SCI-induced cancellous bone loss, albeit via differing mechanisms. Specifically, Scl-Ab increased osteoblast surface and bone formation, indicating direct bone anabolic effects, whereas TE reduced osteoclast surface with minimal effect on bone formation, indicating antiresorptive effects. The deleterious microarchitectural alterations in the trabecular network were also prevented in SCI + Scl-Ab and SCI + TE animals, whereas only Scl-Ab completely prevented the reduction in cortical bone strength. Our findings provide the first evidence indicating that sclerostin inhibition represents a viable treatment to prevent SCI-induced cancellous and cortical bone deficits and provides preliminary rationale for future clinical trials focused on evaluating whether Scl-Ab prevents osteoporosis in the SCI population.

Lean tissue mass and energy expenditure are retained in hypogonadal men with spinal cord injury after discontinuation of testosterone replacement therapy

OBJECTIVE

To determine whether favorable changes to lean tissue mass (LTM), resting energy expenditure (REE), and testosterone (T) that occurred with 12 months of physiological testosterone replacement therapy (TRT) were retained 6 months after discontinuing treatment.

DESIGN

Prospective, open-label, controlled drug intervention trial.

SETTING

Metropolitan area hospitals.

SUBJECTS

Eugonadal (n = 11) and hypogonadal (n = 13) men with chronic spinal cord injury (SCI).

INTERVENTIONS

Hypogonadal subjects received a 5 or 10 mg transdermal T patch daily for 12 months, with adjustment of the dose to normalize the serum T concentration; TRT was discontinued after 12 months (TRT-12M) and subjects were followed for an additional 6 months and re-evaluated (Post-TRT). Total body dual energy X-ray absorptiometry and blood draws were performed at baseline (BL) prior to TRT, TRT-12M, and Post-TRT. Eugonadal subjects did not receive treatment and were evaluated at comparable time points.

RESULTS

There were no significant differences between groups prior to TRT at BL for any of the study endpoints. In the hypogonadal group, a significant increase in LTM was observed from BL to TRT-12M (50.2 ± 7.4 vs. 52.9 ± 6.8 kg, P < 0.01), which persisted Post-TRT compared to BL (52.2 ± 7.8 kg, P < 0.05). The increase in REE from BL to TRT-12M (1283 ± 246 vs. 1410 ± 250 kcal/day) was also retained at Post-TRT (1393 ± 220 kcal/day). These sustained improvements in LTM and REE after termination of anabolic hormonal therapy may be associated with persistent beneficial effects on health and physical function of hypogonadal men with chronic SCI.

Testosterone dose dependently prevents bone and muscle loss in rodents after spinal cord injury

Androgen administration protects against musculoskeletal deficits in models of sex-steroid deficiency and injury/disuse. It remains unknown, however, whether testosterone prevents bone loss accompanying spinal cord injury (SCI), a condition that results in a near universal occurrence of osteoporosis. Our primary purpose was to determine whether testosterone-enanthate (TE) attenuates hindlimb bone loss in a rodent moderate/severe contusion SCI model. Forty (n=10/group), 14 week old male Sprague-Dawley rats were randomized to receive: (1) Sham surgery (T9 laminectomy), (2) moderate/severe (250 kdyne) SCI, (3) SCI+Low-dose TE (2.0 mg/week), or (4) SCI+High-dose TE (7.0 mg/week). Twenty-one days post-injury, SCI animals exhibited a 77-85% reduction in hindlimb cancellous bone volume at the distal femur (measured via μCT) and proximal tibia (measured via histomorphometry), characterized by a >70% reduction in trabecular number, 13-27% reduction in trabecular thickness, and increased trabecular separation. A 57% reduction in cancellous volumetric bone mineral density (vBMD) at the distal femur and a 20% reduction in vBMD at the femoral neck were also observed. TE dose dependently prevented hindlimb bone loss after SCI, with high-dose TE fully preserving cancellous bone structural characteristics and vBMD at all skeletal sites examined. Animals receiving SCI also exhibited a 35% reduction in hindlimb weight bearing (triceps surae) muscle mass and a 22% reduction in sublesional non-weight bearing (levator ani/bulbocavernosus [LABC]) muscle mass, and reduced prostate mass. Both TE doses fully preserved LABC mass, while only high-dose TE ameliorated hindlimb muscle losses. TE also dose dependently increased prostate mass. Our findings provide the first evidence indicating that high-dose TE fully prevents hindlimb cancellous bone loss and concomitantly ameliorates muscle loss after SCI, while low-dose TE produces much less profound musculoskeletal benefit. Testosterone-induced prostate enlargement, however, represents a potential barrier to the clinical implementation of high-dose TE as a means of preserving musculoskeletal tissue after SCI.

Testosterone recovery after polytrauma and scrotal injury in patients from Operation Enduring Freedom and Operation Iraqi Freedom

PURPOSE

We examined the long-term natural history of testosterone recovery in patients with complex battle injuries.

MATERIALS AND METHODS

We retrospectively reviewed the charts of patients who participated in Operation Enduring Freedom and Operation Iraqi Freedom, and underwent urological surgical consultation at Walter Reed Army Medical Center, Washington, D.C. or the National Naval Medical Center, Bethesda, Maryland, from 2001 to August 2011. Of the 192 patient charts reviewed 138 (72%) had testosterone values available. The study inclusion criterion of at least 2 testosterone measurements, including 1 made within 40 days of injury, was met by 84 patients (61%) with testosterone data available. Those treated with bilateral orchiectomy were not required to meet this criterion.

RESULTS

Initial patient testosterone after injury in the testosterone recovery group was inversely proportional to the degree of scrotal injury. In patients in whom testosterone recovered to at least 250 ng/dl the recovery occurred a mean of 4.5 months after injury. Patients who required testosterone replacement had lower initial testosterone (p = 0.0063) and lower testosterone velocity (p <0.0001).

CONCLUSIONS

Monitoring the velocity of testosterone recovery is a viable approach in male patients who receive significant genitourinary trauma. In patients in whom testosterone recovered the recovery occurred within a mean of 5 months after injury. It is reasonable to observe patients with scrotal injuries since testosterone may recover in many of them without intervention.

Osteoporosis in individuals with spinal cord injury

The pathophysiology, clinical considerations, and relevant experimental findings with regard to osteoporosis in individuals with spinal cord injury (SCI) will be discussed. The bone loss that occurs acutely after more neurologically motor complete SCI is unique for its sublesional skeletal distribution and rate, at certain skeletal sites approaching 1% of bone mineral density per week, and its resistance to currently available treatments. The areas of high bone loss include the distal femur, proximal tibia, and more distal boney sites. Evidence from a study performed in monozygotic twins discordant for SCI indicates that sublesional bone loss in the twin with SCI increases for several decades, strongly suggesting that the heightened net bone loss after SCI may persist for an extended period of time. The increased frequency of fragility fracture after paralysis will be discussed, and a few risk factors for such fractures after SCI will be examined. Because vitamin D deficiency, regardless of disability, is a relevant consideration for bone health, as well as an easily reversible condition, the increased prevalence of and treatment target values for vitamin D in this deficiency state in the SCI population will be reviewed. Pharmacological and mechanical approaches to preserving bone integrity in persons with acute and chronic SCI will be reviewed, with emphasis placed on efficacy and practicality. Emerging osteoanabolic agents that improve functioning of WNT/β-catenin signaling after paralysis will be introduced as therapeutic interventions that may hold promise.

Correlates of low testosterone in men with chronic spinal cord injury

Although high rates of serum testosterone deficiency have been reported in men with spinal cord injury (SCI), its determinants and attributes are not yet established. The aim of this study was to recognize, among putative determinants and attributes of androgen deficiency, those significantly associated to low testosterone after adjustment for confounders recognizable in men with chronic SCI. A biochemical androgen deficiency (total testosterone <300 ng/dL) was exhibited by 18 of 51 patients (35.3%). Significant correlates of testosterone levels were as follows: weekly leisure time physical activity (LTPA) explored by the LTPA Questionnaire for people with SCI, body mass index (BMI), homeostatic model assessment of insulin resistance (HOMA-IR), triglycerides and sexual symptoms, explored by the aging males' symptom (AMS) questionnaire. At the multiple linear regression analysis, among putative determinants of low testosterone, only weekly LTPA and BMI exhibited a significant association with testosterone levels, explaining 54.2 and 9.0% of testosterone variability respectively. At the linear regression models, among various putative attributes of androgen deficiency, only lower sexual desire and, at a lesser extent, higher HOMA-IR, exhibited significant associations with lower testosterone levels, after adjustment for BMI, age, comorbidities and weekly LTPA. In conclusion, poor LTPA, high BMI and low sexual desire are independent predictors of low testosterone in men with chronic SCI. This is relevant to clinical practice, as all these features are routinely assessed in rehabilitation settings for SCI. As poor LTPA and high BMI are modifiable life-style related risk factors, prospective studies could clarify whether life-style modification could increase the level of testosterone and improve the low sexual desire, relevant clinical attribute of low testosterone in men with SCI.

Establishment of quantitative severity evaluation model for spinal cord injury by metabolomic fingerprinting

Spinal cord injury (SCI) is a devastating event with a limited hope for recovery and represents an enormous public health issue. It is crucial to understand the disturbances in the metabolic network after SCI to identify injury mechanisms and opportunities for treatment intervention. Through plasma 1H-nuclear magnetic resonance (NMR) screening, we identified 15 metabolites that made up an "Eigen-metabolome" capable of distinguishing rats with severe SCI from healthy control rats. Forty enzymes regulated these 15 metabolites in the metabolic network. We also found that 16 metabolites regulated by 130 enzymes in the metabolic network impacted neurobehavioral recovery. Using the Eigen-metabolome, we established a linear discrimination model to cluster rats with severe and mild SCI and control rats into separate groups and identify the interactive relationships between metabolic biomarkers in the global metabolic network. We identified 10 clusters in the global metabolic network and defined them as distinct metabolic disturbance domains of SCI. Metabolic paths such as retinal, glycerophospholipid, arachidonic acid metabolism; NAD-NADPH conversion process, tyrosine metabolism, and cadaverine and putrescine metabolism were included. In summary, we presented a novel interdisciplinary method that integrates metabolomics and global metabolic network analysis to visualize metabolic network disturbances after SCI. Our study demonstrated the systems biological study paradigm that integration of 1H-NMR, metabolomics, and global metabolic network analysis is useful to visualize complex metabolic disturbances after severe SCI. Furthermore, our findings may provide a new quantitative injury severity evaluation model for clinical use.

Long-term facilitation of ventilation in humans with chronic spinal cord injury

RATIONALE

Intermittent stimulation of the respiratory system with hypoxia causes persistent increases in respiratory motor output (i.e., long-term facilitation) in animals with spinal cord injury. This paradigm, therefore, has been touted as a potential respiratory rehabilitation strategy.

OBJECTIVES

To determine whether acute (daily) exposure to intermittent hypoxia can also evoke long-term facilitation of ventilation after chronic spinal cord injury in humans, and whether repeated daily exposure to intermittent hypoxia enhances the magnitude of this response.

METHODS

Eight individuals with incomplete spinal cord injury (>1 yr; cervical [n = 6], thoracic [n = 2]) were exposed to intermittent hypoxia (eight 2-min intervals of 8% oxygen) for 10 days. During all exposures, end-tidal carbon dioxide levels were maintained, on average, 2 mm Hg above resting values. Minute ventilation, tidal volume, and breathing frequency were measured before (baseline), during, and 30 minutes after intermittent hypoxia. Sham protocols consisted of exposure to room air and were administered to a subset of the participants (n = 4).

MEASUREMENTS AND MAIN RESULTS

Minute ventilation increased significantly for 30 minutes after acute exposure to intermittent hypoxia (P < 0.001), but not after sham exposure. However, the magnitude of ventilatory long-term facilitation was not enhanced over 10 days of intermittent hypoxia exposures.

CONCLUSIONS

Ventilatory long-term facilitation can be evoked by brief periods of hypoxia in humans with chronic spinal cord injury. Thus, intermittent hypoxia may represent a strategy for inducing respiratory neuroplasticity after declines in respiratory function that are related to neurological impairment. Clinical trial registered with www.clinicaltrials.gov (NCT01272011).

Sex steroids and neuroprotection in spinal cord injury: a review of preclinical investigations

Spinal cord injury (SCI) is a debilitating condition that affects motor, sensory and autonomic functions. Subsequent to the first mechanical trauma, secondary events, which include inflammation and glial activation, exacerbate tissue damage and worsen functional deficits. Although these secondary injury mechanisms are amenable to therapeutic interventions, the efficacy of current approaches is inadequate. Further investigations are necessary to implement new therapies that can protect neural cells and attenuate some of the detrimental effects of inflammation while promoting regeneration. Studies on different animal models of SCI indicated that sex steroids, especially 17β-estradiol and progesterone, exert neuroprotective, anti-apoptotic and anti-inflammatory effects, ameliorate tissue sparing and improve functional deficits in SCI. As sex steroid receptors are expressed in a variety of cells including neurons, glia and immune system-related cells which infiltrate the injury epicenter, sex steroids could impact multiple processes simultaneously and in doing so, influence the outcomes of SCI. However, the translation of these pre-clinical findings into the clinical setting presents challenges such as the narrow therapeutic time window of sex steroid administration, the diversity of treatment regimens that have been employed in animal studies and the lack of sufficient information regarding the persistence of the effects in chronic SCI. The current review will summarize some of the major findings in this field and will discuss the challenges associated with the implementation of sex steroids as a promising treatment in human SCI.

Age-related prevalence of low testosterone in men with spinal cord injury

OBJECTIVE

To describe the relationship of advancing age in persons with chronic spinal cord injury (SCI) on the prevalence of low testosterone in men with SCI compared to historical normative data from able-bodied men in the general population.

DESIGN

Retrospective, cross-sectional study. Two hundred forty-three healthy, non-ambulatory outpatient men with chronic SCI from age of 21 to 78 years were included in this retrospective analysis.

RESULTS

Forty-six percent of men with SCI were identified as having low serum total testosterone concentrations (total testosterone <11.3 nmol/l). The age-related decline in SCI for total serum testosterone concentration was 0.6%/year compared to 0.4%/year in the Massachusetts Male Aging Study. Between the third and eighth decade of life, men with SCI had a 15, 39, 50, 53, 58, and 57% prevalence rate of low serum total testosterone, which is higher than values reported for each decade of life for able-bodied men in the Baltimore Longitudinal Study on Aging.

CONCLUSION

Compared with the general population, low serum total testosterone concentration occurs earlier in life in men with SCI, at a higher prevalence by decade of life, and their age-related decline in circulating total testosterone concentration is greater. Studies of T replacement therapy in men with SCI should assist in determining the possible functional and clinical benefits from reversing low serum total testosterone concentration.

Subcutaneous pellet testosterone replacement therapy: the "first steps" in treating men with spinal cord injuries

The authors describe the case of a 36-year-old man who presented with hormone level concerns 6 months after a rock climbing accident that resulted in paraplegia. Hypogonadism was diagnosed, and the patient received subcutaneous pellet testosterone replacement therapy. Within 6 months, the patient had substantial improvement in muscle function and was able to take several steps with the assistance of crutches or a walker. This case highlights the potential improvement in quality of life and overall prognosis resulting from the subcutaneous pellet form of testosterone when used as part of the overall treatment plan in such patients. Considering the overwhelming preponderance of hypogonadism in men with spinal cord injuries, the standard of care for such patients should include screening, laboratory hormone evaluation, and prompt treatment for testosterone deficiency.

Risk of prostate and bladder cancers in patients with spinal cord injury: a population-based cohort study

OBJECTIVE

To evaluate the risk of prostate and bladder cancers in patients with spinal cord injury (SCI).

MATERIALS AND METHODS

We used data obtained from the National Health Insurance system of Taiwan for this study. The SCI cohort contained 54,401 patients with SCI, and each patient was randomly frequency matched with 4 people from the general population (without SCI) based on age, sex, and index date. Incidence rates, SCI cohort to non-SCI cohort rate ratios, and hazard ratios were measured to evaluate the cancer risks.

RESULTS

Patients with SCI showed a significantly lower risk of developing prostate cancer compared with subjects without SCI (adjusted hazard ratio = 0.73; 95% confidence interval = 0.59, 0.90), after accounting for the competing risk of death. No significant difference in the risk of bladder cancer emerged between the SCI and control groups. Further analyses found a higher spinal level of SCI tended to predict a lower risk for prostate cancer.

CONCLUSIONS

Patients with SCI incurred a lower risk for prostate cancer compared with people without SCI. The risk for bladder cancer did not differ between people with or without SCI.

The association of opioid use with incident lower extremity fractures in spinal cord injury

OBJECTIVE

To determine the association between opioid use and lower extremity fracture risk in men with spinal cord injury (SCI).

DESIGN

Retrospective cohort study.

SETTING

Veterans Affairs Healthcare System.

PARTICIPANTS

In total, 7447 male Veterans with a history of a traumatic SCI identified from the Veterans Affairs (VA) Spinal Cord Dysfunction Registry (SCD) from September 2002 through October 2007 and followed through October 2010.

OUTCOME MEASURES

Incident lower extremity fractures by use of opioids.

RESULTS

In individuals identified from the VA SCD Registry 2002-2007, opioid use was quite common, with approximately 70% of the cohort having received a prescription for an opioid. Overall, there were 892 incident lower extremity fractures over the time period of this study (597 fractures in the opioid users and 295 fractures in the non-opioid users). After adjusting for covariates, there was a statistically significant relationship between opioid use and increased risk for lower extremity fractures (hazard ratio 1.82 (95% confidence interval 1.59-2.09)). Shorter duration of use (<6 months) and higher doses were positively related to fracture risk (P < 0.0001).

CONCLUSIONS

Opioid use is quite common in SCI and is associated with an increased risk for lower extremity fractures. Careful attention to fracture prevention is warranted in patients with SCI, particularly upon initiation of an opioid prescription and when higher doses are used.

Impact of spinal cord injury on sexuality: broad-based clinical practice intervention and practical application

This study focuses on the impact a spinal cord injury may have on achieving physical and emotional intimacy, and potential to maximize sexual ability and quality of life. Spinal cord injury is a traumatic, life-altering event that is usually associated with loss of motor and sensory function, as well as sexual impairment. At the time of injury, the individual is faced with devastating loss and an abundance of new information in a setting of extreme stress and challenge. In the acute rehabilitation setting, there is often a considerable void in providing education and resources regarding sexual concerns and needs. There is a positive relationship between sexual education and sexual activity. The impact of inadequate sexual counseling and education as a part of rehabilitation can be deleterious.

31st g. Heiner sell lectureship: secondary medical consequences of spinal cord injury

Persons with spinal cord injury (SCI) have secondary medical consequences of paralysis and/or the consequences of extreme inactivity. The metabolic changes that result from reduced activity include insulin resistance with carbohydrate disorders and dyslipidemia. A higher prevalence of coronary artery calcification was found in persons with SCI than that in matched able-bodied controls. A depression in anabolic hormones, circulating testosterone and growth hormone, has been described. Adverse soft tissue body composition changes of increased adiposity and reduced skeletal muscle are appreciated. Immobilization is the cause for sublesional disuse osteoporosis with an associated increased risk of fragility fracture. Bowel dysmotility affects all segments of the gastrointestinal tract, with an interest in better defining and addressing gastroesophageal reflux disease and difficulty with evacuation. Developing and testing more effective approaches to cleanse the bowel for elective colonoscopy are being evaluated. The extent of respiratory dysfunction depends on the level and completeness of SCI. Individuals with higher spinal lesions have both restrictive and obstructive airway disease. Pharmacological approaches and expiratory muscle training are being studied as interventions to improve pulmonary function and cough strength with the objective of reducing pulmonary complications. Persons with spinal lesions above the 6th thoracic level lack both cardiac and peripheral vascular mechanisms to maintain blood pressure, and they are frequently hypotensive, with even worse hypotension with upright posture. Persistent and/or orthostatic hypotension may predispose those with SCI to cognitive impairments. The safety and efficacy of anti-hypotensive agents to normalize blood pressure in persons with higher level cord lesions is being investigated.

Prevalence of prostate cancer in patients with chronic spinal cord injury

OBJECTIVE

To determine the prevalence of prostate cancer in patients with chronic spinal cord injury (SCI), with regard to the duration, level, and severity of injury.

DESIGN

Retrospective chart review study.

SETTING

Inpatient and outpatient Veterans Affairs spinal cord unit.

PARTICIPANTS

The electronic medical records of 350 veterans with chronic SCI and 344 veterans without SCI as a control group were reviewed.

MAIN OUTCOME MEASURE

Prevalence of prostate cancer in patients with chronic SCI with regard to the duration, level, and severity of injury.

RESULTS

Of 350 veterans with chronic SCI, 7 individuals (2%) had prostate cancer. In comparison, of 344 age-matched veterans without SCI, 18 (5.2%) had prostate cancer. In SCI group with prostate cancer, 2 patients had motor complete injury (American Spinal Cord Injury Association Impairment Scale [AIS] A and B), and 5 patients had motor incomplete injury (AIS C, D, and E). Patients with SCI and with prostate cancer were slightly older (mean [SD] age, 72.14 ± 8.25 years) than the control group (mean [SD] age, 69.83 ± 8.79 years) with cancer.

CONCLUSION

Findings from this study indicate a lower prevalence of prostate cancer among veterans with chronic SCI in comparison with age-matched veterans without SCI. Given the small number of patients with SCI and with prostate cancer in this study, we did not find any statistically significant correlation between the prevalence of prostate cancer and the level, duration, and severity of injury.

Effect of endogenous androgens on 17beta-estradiol-mediated protection after spinal cord injury in male rats

Several groups have recently shown that 17beta-estradiol is protective in spinal cord injury (SCI). Testosterone can be aromatized to 17beta-estradiol and may increase estrogen-mediated protection. Alternatively, testosterone has been shown to increase excitotoxicity in models of central nervous system (CNS) injury. These experiments test the hypothesis that endogenous testosterone in male rats alters 17beta-estradiol-mediated protection by evaluating a delayed administration over a clinically relevant dose range and manipulating testicular-derived testosterone. Adult male Sprague Dawley rats were either gonadectomized or left gonad-intact prior to SCI. SCI was produced by a midthoracic crush injury. At 30 min post SCI, animals received a subcutaneous pellet of 0.0, 0.05, 0.5, or 5.0 mg of 17beta-estradiol, released over 21 days. Hindlimb locomotion was analyzed weekly in the open field. Spinal cords were collected and analyzed for cell death, expression of Bcl-family proteins, and white-matter sparing. Post-SCI administration of the 0.5- or 5.0-mg pellet improved hindlimb locomotion, reduced urinary bladder size, increased neuronal survival, reduced apoptosis, improved the Bax/Bcl-xL protein ratio, and increased white-matter sparing. In the absence of endogenous testicular-derived androgens, SCI induced greater apoptosis, yet 17beta-estradiol administration reduced apoptosis to the same extent in gonadectomized and gonad-intact male rats. These data suggest that delayed post-SCI administration of a clinically relevant dose of 17beta-estradiol is protective in male rats, and endogenous androgens do not alter estrogen-mediated protection. These data suggest that 17beta-estradiol is an effective therapeutic intervention for reducing secondary damage after SCI in males, which could be readily translated to clinical trials.