Prevalence of testosterone deficiency after spinal cord injury. PM R. 2011;3:929-932. [PMID: 22024324 DOI: 10.1016/j.pmrj.2011.07.008]

Effects of spinal cord injury on body composition and metabolic profile - part I

Several body composition and metabolic-associated disorders such as glucose intolerance, insulin resistance, and lipid abnormalities occur prematurely after spinal cord injury (SCI) and at a higher prevalence compared to able-bodied populations. Within a few weeks to months of the injury, there is a significant decrease in total lean mass, particularly lower extremity muscle mass and an accompanying increase in fat mass. The infiltration of fat in intramuscular and visceral sites is associated with abnormal metabolic profiles. The current review will summarize the major changes in body composition and metabolic profiles that can lead to comorbidities such as type 2 diabetes mellitus and cardiovascular diseases after SCI. It is crucial for healthcare specialists to be aware of the magnitude of these changes. Such awareness may lead to earlier recognition and treatment of metabolic abnormalities that may reduce the co-morbidities seen over the lifetime of persons living with SCI.

Systematic Literature Review of the Epidemiology of Nongenetic Forms of Hypogonadism in Adult Males

This study summarizes the literature on the prevalence, incidence, and proportion of patients receiving treatment for male hypogonadism and a systematic literature search was performed for articles published in the last 20 years. Of the 97 studies identified, 96 examined the prevalence, 2 examined the incidence, and 4 examined the proportion of males with hypogonadism patients receiving treatment. Based on studies conducted in Europe and USA, the prevalence of hypogonadism in the general population ranged from 2.1% to 12.8% of middle-aged to older men, with an estimated incidence of 12 new cases per 1,000 person-years. Prevalence was higher among patients with comorbid conditions, such as type 2 diabetes mellitus and obesity. Approximately 10–12% of men with hypogonadism were receiving testosterone treatment. This literature review suggests that there is potentially a significant burden of hypogonadism in the general population. Burden seems to increase with age and in the presence of certain disease conditions. Data suggests that many hypogonadal men who may benefit from testosterone replacement are not receiving treatment. This may be the result of underdiagnosis of the disease, lack of awareness by patients or physicians, irregularities surrounding the diagnostic criteria, and deficiency of long-term safety studies.

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.

SOD therapeutics: latest insights into their structure-activity relationships and impact on the cellular redox-based signaling pathways

SIGNIFICANCE

Superoxide dismutase (SOD) enzymes are indispensable and ubiquitous antioxidant defenses maintaining the steady-state levels of O2·(-); no wonder, thus, that their mimics are remarkably efficacious in essentially any animal model of oxidative stress injuries thus far explored.

RECENT ADVANCES

Structure-activity relationship (half-wave reduction potential [E1/2] versus log kcat), originally reported for Mn porphyrins (MnPs), is valid for any other class of SOD mimics, as it is dominated by the superoxide reduction and oxidation potential. The biocompatible E1/2 of ∼+300 mV versus normal hydrogen electrode (NHE) allows powerful SOD mimics as mild oxidants and antioxidants (alike O2·(-)) to readily traffic electrons among reactive species and signaling proteins, serving as fine mediators of redox-based signaling pathways. Based on similar thermodynamics, both SOD enzymes and their mimics undergo similar reactions, however, due to vastly different sterics, with different rate constants.

CRITICAL ISSUES

Although log kcat(O2·(-)) is a good measure of therapeutic potential of SOD mimics, discussions of their in vivo mechanisms of actions remain mostly of speculative character. Most recently, the therapeutic and mechanistic relevance of oxidation of ascorbate and glutathionylation and oxidation of protein thiols by MnP-based SOD mimics and subsequent inactivation of nuclear factor κB has been substantiated in rescuing normal and killing cancer cells. Interaction of MnPs with thiols seems to be, at least in part, involved in up-regulation of endogenous antioxidative defenses, leading to the healing of diseased cells.

FUTURE DIRECTIONS

Mechanistic explorations of single and combined therapeutic strategies, along with studies of bioavailability and translational aspects, will comprise future work in optimizing redox-active drugs.

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.

Spinal cord injury and male infertility: a review

Spinal cord injuries remain an important factor of morbimortality in current society, involving mainly males from adolescence to adulthood. Among the sequelae caused by spinal cord injuries, the impairment of the sexual system is highly relevant since it affects the quality of sexual life and paternity. Infertility is secondary to multiple events such as erectile dysfunction, anejaculation, seminal biochemical modification and morphology of spermatozoa. Current therapies for the infertile spinal cord injured patient focus on the ejaculation stimulus followed by intrauterine insemination, leaving seminal low quality as the major factor of infertility in these patients. In this scenario, therapy with hyperbaric oxygenation, which is still being studied, represents an alternative treatment since it focuses on the central nervous system injured by the trauma and the testicular tissue in order to decrease spinal damage and to preserve the physiological regulation of the urogenital system as a form of avoiding infertility.

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.