A call to reevaluate cardiac autonomic assessment after spinal cord injury.

This "Perspectives" article puts forward the notion that measuring heart rate variability, or other forms of cardiac autonomic regulation, after spinal cord injury must be performed during a test of autonomic stress. Resting values of heart rate variability are often similar to those obtained from able-bodied individuals, which may therefore be falsely interpreted as normal or healthy autonomic regulation. However, evidence shows that despite normal resting values, cardiac autonomic control is impaired when individual with spinal cord injury are subjected to a cold face test, head-up tilt, or recovery from exercise. Accordingly, examination of cardiac autonomic function must be performed during an autonomic challenge, as resting measures do not accurately reflect the state of cardiovascular regulation after spinal cord injury and can provide false information.

Suppression of Serum Prolactin Levels after Sports Concussion with Prompt Resolution Upon Independent Clinical Assessment To Permit Return-to-Play.

A significant outflow of neurotransmitters and metabolites with associated enhanced cortical excitation occurs after concussive head trauma. Cellular changes in the acute post-injury period cannot be observed directly in humans, and as such, require indirect evidence from systems sufficiently sensitive to central neuronal cellular excitation. Dopamine is a neurotransmitter with numerous targets in the central and peripheral nervous system. Changes to central dopaminergic tone result in reciprocal responses to the level of serum prolactin (PRL). Thus, a concussion may lead to abnormal dopaminergic tone, resulting in dynamic perturbations in the serum PRL concentration. To determine the effect of concussion on serum PRL concentrations, venipuncture was performed in the morning in four male intercollegiate athletes (age, 20 ± 1 years; height, 71 ± 5 inches; weight, 174 ± 21 pounds) within 48 h of concussion and again at 7 and 14 days post-injury. Serum PRL concentrations for each visit were categorized by quartile within the normal range. In all athletes, serum PRL concentrations increased from the lower quartiles in samples obtained closer to the time of injury to the higher quartiles at 14 days post-injury. These serum PRL changes accompanied the resolution of symptoms and the clinical decision to permit return-to-play. It may be postulated that transient augmentation of central dopaminergic tone resulted in inhibition of PRL secretion early after concussion and that disinhibition of PRL release occurred when central dopaminergic tone subsequently returned to baseline levels. This novel observation provides evidence for dopaminergic dysfunction after concussion that may be tracked by determination of serum PRL levels.

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.