The adrenocortical response to brain injury: correlation with the severity of neurologic dysfunction, effects of intoxication, and patient outcome

Alcohol intake before injury and functional and survival outcomes after traumatic brain injury: Pan-Asian trauma outcomes study (PATOS)

There are controversies about the effects of alcohol intake shortly before injury on prognosis of traumatic brain injury (TBI) patients. We investigated the association between alcohol intake and functional/survival outcomes in TBI patients, and whether this effect varied according to age and sex. This was a prospective international multicenter cohort study using the Pan-Asian trauma outcomes study registry in Asian-Pacific countries, conducted on adult patients with TBI who visited participating hospitals. The main exposure variable was alcohol intake before injury, and the main outcomes were poor functional recovery (modified Rankin Scale score, 4-6) and in-hospital mortality. Multivariable logistic regression analyses were conducted to estimate the effects of alcohol intake on study outcomes. Interaction analysis between alcohol intake and age/sex were also performed. Among the study population of 12,451, 3263 (26.2%) patients consumed alcohol before injury. In multivariable logistic regression analysis, alcohol intake was associated with lower odds for poor functional recovery [4.4% vs 6.6%, a odds ratio (95% confidence interval): 0.68 (0.56-0.83)] and in-hospital mortality (1.9% vs 3.1%, 0.64 [0.48-0.86]). The alcohol intake had interaction effects with sex for poor functional recovery: 0.59 (0.45-0.75) for male and 0.94 (0.60-1.49) for female (P for-interaction < .01), whereas there were no interaction between alcohol intake and age. In TBI patients, alcohol intake before injury was associated with lower odds of poor functional recovery and in-hospital mortality, and these effects were maintained in the male group in the interaction analyses.

Growth Hormone Deficiency following Traumatic Brain Injury in Pediatric and Adolescent Patients: Presentation, Treatment, and Challenges of Transitioning from Pediatric to Adult Services

Traumatic brain injury (TBI) is increasingly recognized, with an incidence of approximately 110 per 100,000 in pediatric populations and 618 per 100,000 in adolescent and adult populations. TBI often leads to cognitive, behavioral, and physical consequences, including endocrinopathies. Deficiencies in anterior pituitary hormones (e.g., adrenocorticotropic hormone, thyroid-stimulating hormone, gonadotropins, and growth hormone [GH]) can negatively impact health outcomes and quality of life post-TBI. This review focuses on GH deficiency (GHD), the most common post-TBI pituitary hormone deficiency. GHD is associated with abnormal body composition, lipid metabolism, bone mineral density, executive brain functions, behavior, and height outcomes in pediatric, adolescent, and transition-age patients. Despite its relatively frequent occurrence, post-TBI GHD has not been well studied in these patients; hence, diagnostic and treatment recommendations are limited. Here, we examine the occurrence and diagnosis of TBI, retrospectively analyze post-TBI hypopituitarism and GHD prevalence rates in pediatric and adolescent patients, and discuss appropriate GHD testing strategies and GH dosage recommendations for these patients. We place particular emphasis on the ways in which testing and dosage recommendations may change during the transition phase. We conclude with a review of the challenges faced by transition-age patients and how these may be addressed to improve access to adequate healthcare. Little information is currently available to help guide patients with TBI and GHD through the transition phase and there is a risk of interrupted care; therefore, a strength of this review is its emphasis on this critical period in a patient's healthcare journey.

Improved spatial memory, neurobehavioral outcomes, and neuroprotective effect after progesterone administration in ovariectomized rats with traumatic brain injury: Role of RU486 progesterone receptor antagonist

OBJECTIVES

The contribution of classic progesterone receptors (PR) in interceding the neuroprotective efficacy of progesterone (P4) on the prevention of brain edema and long-time behavioral disturbances was assessed in traumatic brain injury (TBI).

MATERIALS AND METHODS

Female Wistar rats were ovariectomized and apportioned into 6 groups: sham, TBI, oil, P4, vehicle, and RU486. P4 or oil was injected following TBI. The antagonist of PR (RU486) or DMSO was administered before TBI. The brain edema and destruction of the blood-brain barrier (BBB) were determined. Intracranial pressure (ICP), cerebral perfusion pressure (CPP), and beam walk (BW) task were evaluated previously and at various times post-trauma. Long-time locomotor and cognitive consequences were measured one day before and on days 3, 7, 14, and 21 after the trauma.

RESULTS

RU486 eliminated the inhibitory effects of P4 on brain edema and BBB leakage (P<0.05, P<0.001, respectively). RU486 inhibited the decremental effect of P4 on ICP as well as the increasing effect of P4 on CPP (P<0.001) after TBI. Also, RU486 inhibited the effect of P4 on the increase in traversal time and reduction in vestibulomotor score in the BW task (P<0.001). TBI induced motor, cognitive, and anxiety-like disorders, which lasted for 3 weeks after TBI; but, P4 prevented these cognitive and behavioral abnormalities (P<0.05), and RU486 opposed this P4 effect (P<0.001).

CONCLUSION

The classic progesterone receptors have neuroprotective effects and prevent long-time behavioral and memory deficiency after brain trauma.

The blockade of corticotropin-releasing factor 1 receptor attenuates anxiety-related symptoms and hypothalamus-pituitary-adrenal axis reactivity in mice with mild traumatic brain injury

Recent studies have shown that mild traumatic brain injury (mTBI) is associated with higher risk for anxiety-related disorders. Dysregulation in the hypothalamus-pituitary-adrenal (HPA) axis following mTBI has been proposed to be involved in the development of neurobehavioral abnormalities; however, the underlying mechanisms are largely unknown. The aim of this study was to determine whether the corticotropin-releasing-factor-1 (CRF-1) receptor is involved in the regulation of anxiety-related symptoms in a mouse model of mTBI. Animals with or without mTBI received intracerebroventricular injections of a CRF-1 receptor agonist (CRF; 0.01 nmol/mouse) or antagonist (antalarmin; 1 µg/mouse) for 5 days, and then the animals were subjected to anxiety tests (light-dark box and zero maze). The levels of adrenocorticotropic hormone and corticosterone, the most important markers of HPA axis, were also measured after behavioral tests. Our results indicated that mTBI-induced anxiety-related symptoms in mice through increased levels of adrenocorticotropic hormone and corticosterone, showing HPA axis hyperactivity. Interestingly, activation of CRF receptor by a subthreshold dose of CRF resulted in significant increases in anxiety-like behaviors and HPA axis response to stress, whereas blockade of CRF receptors by a subthreshold dose of antalarmin decreased anxiety-related symptoms and HPA axis response to stress in mTBI-induced mice. Collectively, these findings suggest that the CRF-1 receptor plays an important role in the regulation of anxiety-related behaviors following mTBI induction in mice and support the hypothesis that blockade of the CRF-1 receptor may be a promising therapeutic target for anxiety-related disorders in patients with TBI.

An integrated perspective linking physiological and psychological consequences of mild traumatic brain injury

Despite the often seemingly innocuous nature of a mild traumatic brain injury (mTBI), its consequences can be devastating, comprising debilitating symptoms that interfere with daily functioning. Currently, it is still difficult to pinpoint the exact cause of adverse outcome after mTBI. In fact, extensive research suggests that the underlying etiology is multifactorial. In the acute and early sub-acute stages, the pathophysiology of mTBI is likely to be dominated by complex physiological alterations including cellular injury, inflammation, and the acute stress response, which could lead to neural network dysfunction. In this stage, patients often report symptoms such as fatigue, headache, unstable mood and poor concentration. When time passes, psychological processes, such as coping styles, personality and emotion regulation, become increasingly influential. Disadvantageous, maladaptive, psychological mechanisms likely result in chronic stress which facilitates the development of long-lasting symptoms, possibly via persistent neural network dysfunction. So far, a systemic understanding of the coupling between these physiological and psychological factors that in concert define outcome after mTBI is lacking. The purpose of this narrative review article is to address how psychophysiological interactions may lead to poor outcome after mTBI. In addition, a framework is presented that may serve as a template for future studies on this subject.

The interplay between neuroendocrine and sleep alterations following traumatic brain injury

BACKGROUND

Sleep and endocrine disruptions are prevalent after traumatic brain injury (TBI) and are likely to contribute to morbidity.

OBJECTIVE

To describe the interaction between sleep and hormonal regulation following TBI and elucidate the impact that alterations of these systems have on cognitive responses during the posttraumatic chronic period.

METHODS

Review of preclinical and clinical literature describing long-lasting endocrine dysregulation and sleep alterations following TBI. The bidirectional relationship between sleep and hormones is described. Literature describing co-occurrence between sleep-wake disturbances and hormonal dysregulation will be presented. Review of literature describing cognitive effects of seep and hormones. The cognitive and functional impact of sleep disturbances and hormonal dysregulation is discussed within the context of TBI.

RESULTS/CONCLUSIONS

Sleep and hormonal alterations impact cognitive and functional outcome after TBI. Diagnosis and treatment of these disturbances will impact recovery following TBI and should be considered in the post-acute rehabilitative setting.

Initial free cortisol dynamics following blunt multiple trauma and traumatic brain injury: A clinical study

Objective

To determine free and total cortisol serum concentrations in the first 24 h after trauma and to evaluate the influence of traumatic brain injury (TBI) on their dynamics.

Methods

This prospective cohort study enrolled patients who had experienced multiple trauma and were admitted to a level 1 trauma centre. The patients were divided in two groups based on the presence of TBI according to clinical and radiological findings. Blood was collected initially as well as at 12 h and 24 h after the traumatic injury. Total cortisol, corticosteroid binding globulin (CBG) and free cortisol levels were determined.

Results

The study analysed data from 49 patients (36 males and 13 females) with a mean ± SD age of 45.0 ± 16.0 years. Of these, 36 presented with TBI and 13 had multiple injuries without TBI. Patients with TBI showed significantly lower concentrations of total cortisol and free cortisol compared with patients without TBI. Repeated measures analysis revealed different concentration dynamics in patients with TBI, with no increase in cortisol after trauma.

Conclusion

Multiple trauma patients with TBI are at risk of acute impaired cortisol secretion and show an attenuated stress response as early as 12 h after injury.

Role of Endogenous and Exogenous Corticosterone on Behavioral and Cognitive Responses to Low-Pressure Blast Wave Exposure

The complex interactions and overlapping symptoms of comorbid post-traumatic stress disorder (PTSD) and mild traumatic brain injury (mTBI) induced by an explosive blast wave have become a focus of attention in recent years, making clinical distinction and effective intervention difficult. Because dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is thought to underlie trauma-related (psycho)pathology, we evaluated both the endogenous corticosterone response and the efficacy of exogenous hydrocortisone treatment provided shortly after blast exposure. We employed a controlled experimental blast-wave paradigm in which unanesthetized animals were exposed to visual, auditory, olfactory, and tactile effects of an explosive blast wave produced by exploding a thin copper wire. Endogenous corticosterone concentrations were evaluated at different time points (before, and 3 h, 5 h and 17 days) after blast exposure. Subsequently, the efficacy of exogenous hydrocortisone (25 mg/kg^-1 or 125 mg/kg^-1) injected intraperitoneally 1 h after exposure was compared with that of a similarly timed saline injection. Validated cognitive and behavioral tests were used to assess both PTSD and mTBI phenotypes on days 7-14 following the blast. Retrospective analysis revealed that animals demonstrating the PTSD phenotype exhibited a significantly blunted endogenous corticosterone response to the blast compared with all other groups. Moreover, a single 125 mg/kg^-1 dose of hydrocortisone administered 1 h after exposure significantly reduced the occurrence of the PTSD phenotype. Hydrocortisone treatment did not have a similar effect on the mTBI phenotype. Results of this study indicate that an inadequate corticosteroid response following blast exposure increases risk for PTSD phenotype, and corticosteroid treatment is a potential clinical intervention for attenuating PTSD. The differences in patterns of physiological and therapeutic response between PTSD and mTBI phenotypes lend credence to the retrospective behavioral and cognitive classification criteria we designed, and is in keeping with the assumption that mTBI and PTSD phenotypes may reflect distinct underlying biological and clinical profiles.

Update of Endocrine Dysfunction following Pediatric Traumatic Brain Injury

Traumatic brain injuries (TBI) are common occurrences in childhood, often resulting in long term, life altering consequences. Research into endocrine sequelae following injury has gained attention; however, there are few studies in children. This paper reviews the pathophysiology and current literature documenting risk for endocrine dysfunction in children suffering from TBI. Primary injury following TBI often results in disruption of the hypothalamic-pituitary-adrenal axis and antidiuretic hormone production and release, with implications for both acute management and survival. Secondary injuries, occurring hours to weeks after TBI, result in both temporary and permanent alterations in pituitary function. At five years after moderate to severe TBI, nearly 30% of children suffer from hypopituitarism. Growth hormone deficiency and disturbances in puberty are the most common; however, any part of the hypothalamic-pituitary axis can be affected. In addition, endocrine abnormalities can improve or worsen with time, having a significant impact on children’s quality of life both acutely and chronically. Since primary and secondary injuries from TBI commonly result in transient or permanent hypopituitarism, we conclude that survivors should undergo serial screening for possible endocrine disturbances. High indices of suspicion for life threatening endocrine deficiencies should be maintained during acute care. Additionally, survivors of TBI should undergo endocrine surveillance by 6–12 months after injury, and then yearly, to ensure early detection of deficiencies in hormonal production that can substantially influence growth, puberty and quality of life.

Prospective investigation of anterior pituitary function in the acute phase and 12 months after pediatric traumatic brain injury

PURPOSE

Although head trauma is common in childhood, there is no enough prospective study investigating both acute phase and 12 months after injury. Therefore, a prospective clinical trial was planned to evaluate the pituitary function in childhood in the acute and chronic phase after traumatic brain injury (TBI).

METHODS

Forty-one children (27 boys and 14 girls, mean age 7 ± 4.3), who were admitted to neurosurgery intensive care unit due to head trauma, were included. Twenty-one (51.2 %) patients had mild, 10 (24.4 %) had moderate, and 10 (24.4 %) had severe TBI. Twenty-two of them were reevaluated 12 months after TBI. Basal pituitary hormone levels were measured during acute (first 24 h) and chronic phase of TBI. Additionally, in the chronic phase, GHRH-arginine test was used for the diagnosis of growth hormone (GH) deficiency.

RESULTS

In the acute phase, 10 patients (24.4 %) had ACTH deficiency, and the overall 44.3 % of patients had at least one pituitary hormone dysfunction. All the pituitary hormone deficiencies during the acute phase were recovered after 12 months. Two patients (9.1 %) had new-onset GH deficiency in the chronic phase, and in one of them, ACTH deficiency was also present.

CONCLUSIONS

Present prospective data clearly demonstrated that most of the hormonal changes in the early acute phase were transient, suggesting an adaptive response, and these changes did not predict the hormone deficiencies after 1 year. In the chronic phase, although GH deficiency was present, the frequency of TBI-induced hypopituitarism was clearly lower than the adult patients.

The effect of different intensities of treadmill exercise on cognitive function deficit following a severe controlled cortical impact in rats

Exercise has been proposed for the treatment of traumatic brain injury (TBI). However, the proper intensity of exercise in the early phase following a severe TBI is largely unknown. To compare two different treadmill exercise intensities on the cognitive function following a severe TBI in its early phase, rats experienced a controlled cortical impact (CCI) and were forced to treadmill exercise for 14 days. The results revealed that the rats in the low intensity exercise group had a shorter latency to locate a platform and a significantly better improvement in spatial memory in the Morris water maze (MWM) compared to the control group (p < 0.05). The high intensity exercise group showed a longer latency and a mild improvement in spatial memory compared to the control group rats in the MWM; however, this difference was not statistically significant (p > 0.05). The brain-derived neurotrophic factor (BDNF) and p-CREB protein levels in the contralateral hippocampus were increased significantly in the low intensity exercise group. Our results suggest that 2 weeks of low intensity of treadmill exercise is beneficial for improving cognitive function and increasing hippocampal BDNF expression after a severe TBI in its early phase.

Endocrine changes after pediatric traumatic brain injury

Traumatic brain injury (TBI) is a very common occurrence in childhood, and can lead to devastating long term consequences. Recent research has focused on the potential endocrine consequences of TBI in adults. The research in children is less robust. This paper reviews current literature regarding TBI and possible hypothalamic and pituitary deficiencies in childhood. Acute endocrine changes are commonly found after TBI in pediatric patients, which can include changes in hypothalamic-pituitary-adrenal axis and antidiuretic hormone production and release. In the long term, both temporary and permanent alterations in pituitary function have been found. About 30% of children have hypopituitarism up to 5 years after injury. Growth hormone deficiency and disturbances in puberty are the most common, but children can also experience ACTH deficiency, diabetes insipidus, central hypothyroidism, and elevated prolactin. Every hormonal axis can be affected after TBI in children, although growth hormone deficiency and alterations in puberty are the most common. Because transient and permanent hypopituitarism is common after TBI, survivors should be screened serially for possible endocrine disturbances. These children should undergo routine surveillance at least 1 year after injury to ensure early detection of deficiencies in hormonal production in order to permit normal growth and development.

Differential effects of voluntary and forced exercise on stress responses after traumatic brain injury

Voluntary exercise increases levels of brain-derived neurotrophic factor (BDNF) after traumatic brain injury (TBI) when it occurs during a delayed time window. In contrast, acute post-TBI exercise does not increase BDNF. It is well known that increases in glucocorticoids suppress levels of BDNF. Moreover, recent work from our laboratory showed that there is a heightened stress response after fluid percussion injury (FPI). In order to determine if a heightened stress response is also observed with acute exercise, at post-injury days 0-4 and 7-11, corticosterone (CORT) and adrenocorticotropic hormone (ACTH) release were measured in rats running voluntarily or exposed to two daily 20-min periods of forced running wheel exercise. Forced, but not voluntary exercise, continuously elevated CORT. ACTH levels were initially elevated with forced exercise, but decreased by post-injury day 7 in the control, but not the FPI animals. As previously reported, voluntary exercise did not increase BDNF in the FPI group as it did in the control animals. Forced exercise did not increase levels of BDNF in any group. It did, however, decrease hippocampal glucocorticoid receptors in the control group. The results suggest that exercise regimens with strong stress responses may not be beneficial during the early post-injury period.

The pathophysiology of concussions in youth

Mild traumatic brain injury, especially sport-related concussion, is common among young persons. Consequences of transient pathophysiologic dysfunction must be considered in the context of a developing or immature brain, as must the potential for an accumulation of damage with repeated exposure. This review summarizes the underlying neurometabolic cascade of concussion, with emphasis on the young brain in terms of acute pathophysiology, vulnerability, alterations in plasticity and activation, axonal injury, and cumulative risk from chronic, repetitive damage, and discusses their implications in the context of clinical care for the concussed youth, highlighting areas for future investigation.

Ethanol intoxication is associated with a lower incidence of admission coagulopathy in severe traumatic brain injury patients

The aim of this study was to determine the impact of ethanol (ETOH) on the incidence of severe traumatic brain injury (sTBI)-associated coagulopathy and to examine the effect of ETOH on in-hospital outcomes in patients sustaining sTBI. Patients admitted to the surgical intensive care unit from June 2005 through December 2008 following sTBI, defined as a head Abbreviated Injury Scale (AIS) score ≥3, were retrospectively identified. Patients with a chest, abdomen, or extremity AIS score >3 were excluded to minimize the impact of extracranial injuries. Criteria for sTBI-associated coagulopathy included thrombocytopenia and/or elevated International Normalized Ratio (INR) and/or prolonged activated partial thromboplastin time (aPTT). The incidence of admission coagulopathy, in-hospital complications, and mortality were compared between patients who were ETOH positive [ETOH (+)] and ETOH negative [ETOH (-)]. During the study period, there were 439 patients with ETOH levels available for analysis. Overall, 46.5% (n=204) of these patients were ETOH (+), while 53.5% (n=235) were ETOH (-). Coagulopathy was significantly less frequent in the ETOH (+) patients compared to their ETOH (-) counterparts (5.4% versus 15.3%; adjusted p<0.001). In the forward logistic regression analysis, a positive ETOH level proved to be an independent protective factor for admission coagulopathy [OR (95% CI)=0.24 (0.10,0.54; p=0.001]. ETOH (+) patients had a significantly lower in-hospital mortality rate than ETOH (-) patients [9.8% versus 16.6%; adjusted p=0.011; adjusted OR (95% CI)=0.39 (0.19,0.81)]. For brain-injured patients arriving alive to the hospital, ETOH intoxication is associated with a significantly lower incidence of early coagulopathy and in-hospital mortality. Further research to establish the pathophysiologic mechanisms underlying any potential beneficial effect of ETOH on the coagulation system following sTBI is warranted.

Loss of cortisol circadian rhythm in patients with traumatic brain injury: a microdialysis evaluation

BACKGROUND

Traumatic brain injury (TBI) is commonly associated with disturbances of the hypothalamic-pituitary-adrenal axis secretion. Cerebral microdialysis techniques have been recently applied to measure brain interstitial cortisol levels.

METHODS

We evaluated for the first time the circadian rhythm of cortisol secretion at 08:00, 16:00, and 24:00 h in the acute phase of TBI by determination of total serum and brain interstitial cortisol levels (microdialysis samples) in 10 patients with TBI. Non-parametric Friedman's two way analysis of variance test was used.

RESULTS

Mean age was 29.8 ± 13.6 years. Median Glasgow Coma Scale score after resuscitation was 5 (range 3-10). No differences were found in total serum (P = 0.26) and brain interstitial cortisol (P = 0.77) in the whole sample. Intraindividual analysis showed that circadian variability was lost in all patients, both in serum and brain interstitial cortisol samples in the acute phase after TBI.

CONCLUSION

In our series, circadian variability of cortisol evaluated by serum and cerebral microdialysis samples seems to be lost in TBI patients.

Heightening of the stress response during the first weeks after a mild traumatic brain injury

The effects of a mild traumatic brain injury range from white matter disruption to affective disorders. We set out to determine the response to restraint-induced stress after a mild fluid-percussion injury (FPI), an experimental model for brain injury. Hypothalamic-pituitary-adrenal (HPA) axis regulation of corticosterone (CORT) and adrenocorticotropic hormone (ACTH) was determined during the first post-injury weeks, which corresponds to the same time period when rehabilitative exercise has been shown to be ineffective after a mild FPI. Adult male rats underwent either an FPI or sham injury. Additional rats were only exposed to anesthesia. HPA regulation was evaluated by measuring the effects of dexamethasone (DEX) treatment on CORT and ACTH. Tail vein blood was collected following 30-min restraint stress, at post-injury days (PID) 1, 7 and 14, prior to (0 min) and at 30, 60, 90 and 120 min after stress onset. Results from these studies indicate that the stress response was significantly more pronounced after FPI in that CORT and ACTH restraint-induced increases were more pronounced and longer lasting compared to controls. DEX suppression of CORT and ACTH was observed in all groups, suggesting that stress hyper-responsiveness after mild FPI is not attributable to reduced sensitivity of CORT feedback regulation. The increased sensitivity to stressful events in the first two post-injury weeks after a mild FPI may have a negative impact on early rehabilitative therapies.

Serum ethanol levels: predictor of survival after severe traumatic brain injury

BACKGROUND

Recent studies have suggested that moderate doses of ethanol (ETOH) before traumatic brain injury (TBI) may have a neuroprotective role.

OBJECTIVE

: The objective of this study is to investigate the effects of serum ETOH levels on outcomes after TBI. Our hypothesis was that ETOH exposure is associated with improved survival in severe TBI patients and that the serum ETOH levels on admission correlate with survival.

METHODS

All patients sustaining severe TBI (head abbreviated injury score >or=3) admitted to the Surgical Intensive Care Unit at the Los Angeles County + University of Southern California Medical Center from January 2000 to December 2005 who had a serum ETOH level measured on admission were analyzed. Patients were classified into ETOH-positive and ETOH-negative groups, according to the serum ETOH levels and compared for differences in outcomes using logistic regression to adjust for clinically and statistically relevant confounding factors.

RESULTS

During the 5-year study period, 482 severe TBI patients admitted to the Surgical Intensive Care Unit at Los Angeles County + University of Southern California Medical Center had a serum ETOH level measured on admission. A total of 47% of severe TBI patients were tested for ETOH. ETOH levels were positive in 37% (179) and negative in 63% (303) of the TBI patients. The ETOH-positive group had a higher percentage of males (91% vs. 79%, p = 0.001), lower percentage of penetrating injuries (9% vs. 20%, p = 0.002), and lower injury severity score (25.7 +/- 11.5 vs. 28.4 +/- 14.1, p = 0.05). Overall mortality was significantly lower in the ETOH-positive group at 27% versus 40% (odds ratio = 0.55, 95% confidence interval: 0.37-0.82; p = 0.004). This survival benefit remained significant after multivariable analysis (adjusted odds ratio = 0.54, 95% confidence interval: 0.31-0.92; adjusted p = 0.02). The mean serum ETOH level was significantly higher for survivors than for nonsurvivors (0.11 +/- 0.21 vs. 0.05 +/- 0.10, p < 0.001). The serum ETOH levels significantly correlated with the probability of survival (r = 0.21, p < 0.001), but this correlation was not strong as shown by the low r value.

CONCLUSION

The results of this study suggest that elevated ETOH serum levels are independently associated with higher survival in patients with severe traumatic brain injuries. Additional research is required to further investigate the mechanism and potential therapeutic implications of this association.

Relationship between plasma adrenocorticotropin hormone and intensive care unit survival in early traumatic brain injury

BACKGROUND

Hypothalamic pituitary adrenal response has been recently evaluated in patients with traumatic brain injury (TBI) with different results. Our objective was to study this response and its relationship with outcome in the early stage after TBI.

METHODS

We conducted a prospective observational clinical study in the intensive care unit of a tertiary level university hospital. The study included 50 consecutive patients who suffered isolated TBI. Intracranial pressure (ICP) was measured by an intraparenchymal probe. All patients were sedated and mechanically ventilated. Second-level measures were provided as per protocol, when needed. We measured plasma adrenocorticotropin hormone (ACTH) levels, as well as baseline and stimulated serum cortisol after a high-dose corticotrophin stimulation test, within 2 days after TBI for all patients.

RESULTS

Mean age was 36 +/- 18 (range 16-77) years. Forty-four (88%) were male. Median Glasgow Coma Scale score was 7. Mean ACTH was 15.4 +/- 19.8 pg/mL. Mean baseline cortisol was 14.8 +/- 9.0 microg/dL and mean stimulated cortisol was 27.1 +/- 7.3 microg/dL and 30.5 +/- 7.2 microg/dL at 30 and 60 minutes, respectively. Baseline and stimulated cortisol were not correlated with mortality. Logistic regression analysis revealed that, either plasma ACTH levels <9 pg/mL or lack of indication to provide second-level measures to control ICP were significant independent predictors of survival.

CONCLUSIONS

The presence of a low plasma ACTH concentration at an early stage of TBI and lack of indication to provide second-level measures to control ICP were associated with a higher intensive care unit survival.

One-year follow-up of patients with mild traumatic brain injury: occurrence of post-traumatic stress-related symptoms at follow-up and serum levels of cortisol, S-100B and neuron-specific enolase in acute phase

OBJECTIVE

To investigate serum levels of cortisol (a biochemical marker of stress), S-100B and neuron-specific enolase (two biochemical markers of brain tissue injury), in acute phase in mild traumatic brain injury patients and the occurrence of post-traumatic stress-related symptoms 1 year after the trauma.

METHODS

Blood samples were taken in patients (n = 88) on admission and approximately 7 hours later for analysis. Occurrence of post-traumatic stress-related symptoms was assessed for 69 patients using items from the Impact of Event Scale questionnaire (IES) at follow-up at 15 +/- 4 months after the injury.

RESULTS

Serum levels of cortisol were more increased in the first sample (cortisol/1, 628.9 +/- 308.9 nmol L-1) than in the second blood sample (cortisol/2, 398.2 +/- 219.4 nmol L-1). The difference between these samples was statistically significant (p < 0.001). Altogether 12 patients (17%) showed post-traumatic stress related symptoms at the time of the follow-up. Stepwise forward logistic regression analysis of symptoms and serum concentrations of markers revealed that only S-100B in the second sample was statistically significantly (p < 0.05) associated to symptoms (three symptoms of the avoidance sub-set of IES).

CONCLUSION

A major increase in serum concentrations of cortisol indicates that high stress levels were reached by the patients, in particular shortly ( approximately 3 hours) after the trauma. The association between the occurrence of post-traumatic stress related symptoms and serum levels of S-100B (generally considered as a biochemical marker of brain injury) seem to reflect the complexity of interactions between brain tissue injury and the ensemble of stress reactions.

Acute secondary adrenal insufficiency after traumatic brain injury: a prospective study

OBJECTIVE

To determine the prevalence, time course, clinical characteristics, and effect of adrenal insufficiency (AI) after traumatic brain injury (TBI).

DESIGN

Prospective intensive care unit-based cohort study.

SETTING

Three level 1 trauma centers.

PATIENTS

A total of 80 patients with moderate or severe TBI (Glasgow Coma Scale score, 3-13) and 41 trauma patients without TBI (Injury Severity Score, >15) enrolled between June 2002 and November 2003.

MEASUREMENTS

Serum cortisol and adrenocorticotropic hormone levels were drawn twice daily for up to 9 days postinjury; AI was defined as two consecutive cortisols of < or =15 microg/dL (25th percentile for extracranial trauma patients) or one cortisol of < 5 microg/dL. Principal outcome measures included: injury characteristics, hemodynamic data, usage of vasopressors, metabolic suppressive agents (high-dose pentobarbital and propofol), etomidate, and AI status.

MAIN RESULTS

AI occurred in 42 TBI patients (53%). Adrenocorticotropic hormone levels were lower at the time of AI (median, 18.9 vs. 36.1 pg/mL; p = .0001). Compared with patients without AI, those with AI were younger (p = .01), had higher injury severity (p = .02), had a higher frequency of early ischemic insults (hypotension, hypoxia, severe anemia) (p = .02), and were more likely to have received etomidate (p = .049). Over the acute postinjury period, patients with AI had lower trough mean arterial pressure (p = .001) and greater vasopressor use (p = .047). Mean arterial pressure was lower in the 8 hrs preceding a low (< or =15 microg/dL) cortisol level (p = .003). There was an inverse relationship between cortisol levels and vasopressor use (p = .0005) and between cortisol levels within 24 hrs of injury and etomidate use (p = .002). Use of high-dose propofol and pentobarbital was strongly associated with lower cortisol levels (p < .0001).

CONCLUSIONS

Approximately 50% of patients with moderate or severe TBI have at least transient AI. Younger age, greater injury severity, early ischemic insults, and the use of etomidate and metabolic suppressive agents are associated with AI. Because lower cortisol levels were associated with lower blood pressure and higher vasopressor use, consideration should be given to monitoring cortisol levels in intubated TBI patients, particularly those receiving high-dose pentobarbital or propofol. A randomized trial of stress-dose hydrocortisone in TBI patients with AI is underway.

Hypothalamic-pituitary dysfunction in critically ill patients with traumatic and nontraumatic brain injury

BACKGROUND

A significant number of studies have shown that critically ill patients with brain injury (BI) frequently exhibit abnormal pituitary hormonal responses during the immediate postinjury period.

DISCUSSION

The elucidation of endocrine alterations depends on the criteria used, the diagnostic tests applied, and the timing of testing in relation to BI. The pattern of the detected hormonal abnormalities shows considerable variability. Altered endocrine responses are due mostly to hypothalamic changes rather than to pituitary dysfunction. Several studies have examined the correlation between hormonal alterations and BI severity, but the results are inconsistent. Furthermore, it remains currently unclear whether and how pituitary abnormalities adversely affect the clinical course of BI patients during the period of critical illness. On the basis of current knowledge, with the exception of clinically significant relative adrenal deficiency and diabetes insipidus, the other endocrine alterations do not seem to require any therapeutic intervention in severely ill BI patients. It is also uncertain whether hormonal abnormalities detected in the early post-BI period persist for the rest of these patients' lives.

CONCLUSIONS

In view of current evidence indicating a high incidence of pituitary dysfunction even years following BI it is recommended that repetition of endocrine evaluation should be performed during the rehabilitation phase in all patients.

Impact of a unilateral brain lesion on cortisol secretion and emotional state: anterior/posterior dissociation in humans

The main goal of this study was to evaluate whether a unilateral brain lesion in a human population is associated with a modification of the circadian cortisol secretion profile, and/or patient's emotional state. The second goal of this study was to assess whether there would be differences in both the pattern of cortisol secretion and emotional state in brain-damaged patients as a function of side of lesion, and localization (anterior vs posterior) of lesion. Eight patients with a left cortical lesion, six patients with a right cortical lesion, four patients with basal ganglia lesions (2 left and 2 right) and ten healthy volunteers were evaluated daily on measures of salivary cortisol levels and subjective feelings of joy and sadness at 0700, 1200, 1600 and 1900 hours over a 15-day period. Patients with cortical brain lesions presented higher cortisol levels and higher scores of sadness at the time of the morning peak (7:00 am), when compared to healthy volunteers and patients with basal ganglia lesions. Laterality of the lesion was not related to cortisol secretion, but frontal damage (anterior lesion) was associated with higher cortisol levels at the time of the morning peak (7:00 am) when compared to more posterior damage. There was no significant correlation between basal circulating levels of cortisol and emotional states in patients and healthy subjects. The results of this study suggest that hypothalamic-pituitary-adrenal (HPA) axis dysregulation is associated with unilateral injury particularly in frontal areas. These results, obtained in a human population, go along with recent animal studies reporting an implication of frontal regions in HPA activity.

Acute ethanol intake attenuates inflammatory cytokines after brain injury in rats: a possible role for corticosterone

It has been reported that acute ethanol intoxication exerts dose-dependent effects, both beneficial and detrimental, on the outcome of traumatic brain injury (TBI), although the mechanism(s) has not been determined. Given that pro-inflammatory cytokines are either neuroprotective or neurotoxic, depending on their tissue levels, ethanol-induced alterations in brain cytokine production may be involved in determining the recovery after TBI. The present study was undertaken to examine the effect of acute ethanol pretreatments (producing blood alcohol concentrations of 100+/-16 mg/dL, and 220+/-10 mg/dL, considered low and intoxicating doses, respectively) on interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) levels in discrete brain regions. In addition, serum corticosterone levels were also examined because the hormone is a modulator of cytokine production, its secretion is stimulated by ethanol, and it has been associated with the severity of post-injury neurologic dysfunction. The data presented in this report demonstrate that moderate cortical impact brain injury elicits a marked increase in IL-1beta and TNF-alpha in the injured cortex as well as in the hippocampus ipsilateral to the injury. Ethanol pretreatment lowered cytokine levels in the cortex, hippocampus and hypothalamus in a dose-dependent manner after TBI compared to the untreated injured rats. Serum corticosterone levels were markedly increased in the injured rats, and were further augmented in the ethanol-pretreated injured animals in a dose-dependent manner. Our findings suggest that ethanol-induced decrease in pro-inflammatory cytokine production may be linked to increased circulating corticosterone, both of which may contribute to the outcome of brain injury.

The hypothalamo-pituitary-adrenal axis response to experimental traumatic brain injury

Alterations in the hypothalamo-pituitary-adrenal (HPA) axis following traumatic brain injury have not been documented in detail. We used fluid percussion injury (FPI) to evaluate the early changes in components of the HPA axis following experimental traumatic brain injury. Wistar rats were sacrificed at 2 or 4 h following sham or FPI surgery. In situ hybridization histochemistry was used to determine the expression of mRNAs of corticotrophin releasing hormone (CRH) and arginine vasopressin (AVP) in the hypothalamus and pro-opiomelanocortin (POMC) in the pituitary. A group of animals undergoing no surgery were used as control. Repeated blood sampling from an indwelling catheter demonstrated that plasma corticosterone (CORT) levels peaked 30 min following surgery in sham and FPI animals but there was no significant difference in CORT concentration between these groups at any time. Pituitary POMC expression was increased following sham and FPI surgery (compared with control non-operated animals) but with no significant difference between the two groups undergoing surgery. Hypothalamic CRH mRNA expression was significantly higher in animals undergoing FPI compared with sham surgery. Hypothalamic AVP mRNA expression was not significantly increased when compared with control nonoperated animals. These data indicate that the anaesthesia and/or surgery associated with FPI or sham surgery induces a generalised activation of the HPA axis. The selective increase in CRH mRNA in animals undergoing FPI may be due to specific effects of traumatic brain injury rather than a general stress response and may suggest an additional neurotransmitter role for CRH following head injury. The absence of an AVP response suggests that the effects of FPI may be mediated through the CRH-alone-containing subpopulation of neurons.

Traumatic brain injury reduces hippocampal alpha7 nicotinic cholinergic receptor binding

Changes in the expression of central nervous system (CNS) neurotransmitter receptors may contribute to behavioral and physiological deficits that occur following traumatic brain injury (TBI). Studies investigating the neurochemical basis for the protracted cognitive dysfunction that follows TBI have focused in part on cholinergic mechanisms. The present study compared the effects of mild and moderate cortical contusion injury (CCI) on the density of cholinergic receptor subtypes, NMDA-type glutamate receptors, and calcium channel expression. Quantitative autoradiography was used to determine the effects of CCI on receptor expression, 48 h following injury. The most robust and consistent change in receptor binding was in the density of alpha7 nicotinic receptors as determined by alpha-[125I]-bungarotoxin (BTX) binding. Bilateral deficits in BTX binding were present following both mild and moderate levels of injury. In contrast, changes in the density of alpha3/alpha4 nAChr's, muscarinic AChr's, NMDA-type glutamate receptors, and L-type calcium channel expression were more regionally restricted and lower in magnitude, as compared to changes in BTX binding. The high calcium permeability of the alpha7 nAChr may be related to the extensive decrease in BTX binding that occurs following TBI.

Regulation of the hypothalamic-pituitary-adrenal axis by cytokines: actions and mechanisms of action

Glucocorticoids are hormone products of the adrenal gland, which have long been recognized to have a profound impact on immunologic processes. The communication between immune and neuroendocrine systems is, however, bidirectional. The endocrine and immune systems share a common "chemical language," with both systems possessing ligands and receptors of "classical" hormones and immunoregulatory mediators. Studies in the early to mid 1980s demonstrated that monocyte-derived or recombinant interleukin-1 (IL-1) causes secretion of hormones of the hypothalamic-pituitary-adrenal (HPA) axis, establishing that immunoregulators, known as cytokines, play a pivotal role in this bidirectional communication between the immune and neuroendocrine systems. The subsequent 10-15 years have witnessed demonstrations that numerous members of several cytokine families increase the secretory activity of the HPA axis. Because this neuroendocrine action of cytokines is mediated primarily at the level of the central nervous system, studies investigating the mechanisms of HPA activation produced by cytokines take on a more broad significance, with findings relevant to the more fundamental question of how cytokines signal the brain. This article reviews published findings that have documented which cytokines have been shown to influence hormone secretion from the HPA axis, determined under what physiological/pathophysiological circumstances endogenous cytokines regulate HPA axis activity, established the possible sites of cytokine action on HPA axis hormone secretion, and identified the potential neuroanatomic and pharmacological mechanisms by which cytokines signal the neuroendocrine hypothalamus.

[Is the metabolic response self-limited in head trauma? Analysis of acute phase proteins and glycemia]

There are many reports supporting a self-limitation mechanism involved with hypermetabolic response after severe cranial injury. It was proposed a study with severe head injury patients, in three stages of the evolution. The first 7 days after admission (moment 1-M1), the second three days latter (M2) and the last 7 days after the first (M3). Among male patients with severe head injury, attended between January 1992 and December 1993 in University Hospital of Botucatu, UNESP, were selected 28 male patients, with Glasgow severity scale between 4 and 6, with pO2 < 70 mm Hg, weighting 60 kg or more. Among these patients, 6 finished the study, including analysis of the excretion of N, acute phase proteins, glycemia, triglycerides and amine nitrogen. During the study there were no changes in nitrogen balance and there was a decrease in protein C-reative. Glycemia tends to fall within two weeks after injury. The authors make some considerations about possible mechanisms involved in brain modulation associated with the period of dependence of hypermetabolism and hypercatabolism after closed brain injury. There are some evidences that the brain responds to head trauma with a gobal non specific way, which tends to be reorganized beyond the first two weeks after lesion. The study does not show any influence of the type and severity of head trauma.

Stress and Critical Illness: The Integrated Immune/Hypothalamic-Pituitary-Adrenal Axis Response

Critical illness leads to a coordinated reaction that is categorized as the stress response; activation of the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system leads to metabolic and cardiovascular changes that are generally directed toward maintenance of homeostasis. The HPA axis and the sympathetic nervous system are linked via reciprocally activating brainstem pathways. The immune system acts via cytokines, which are hormones, to activate the HPA axis. Glucocorticoid secretion suppresses immune activity, thus completing an immune-HPA feedback loop. Restraint of immune activity may be a major function of glucocorticoids during stress, thus averting the potential for immune-mediated damage to healthy tissues. Cortisol also acts to produce adaptive metabolic, cardiovascular, and cognitive changes. Activation of the stress system is also associated with inhibition of thyroid, gonadal, and growth axes through neuroendocrine and peripheral mechanisms; such effects can be seen as directed toward conservation of energy. There is growing evidence that hyperfunction and hypofunction of the integrated stress system may lead to a variety of previously unexplained disorders. Recently, a more detailed understanding of the stress system combined with astute clinical observation of critically ill patients has led to promising new avenues for therapeutic investigation.

Prognostic indicators in medical rehabilitation of traumatic brain injury: a commentary and review

The National Information System (NIS) project is developing consensus opinion regarding a proposed structural framework for the prognostic data to be collected as part of this proposed multicenter research effort on severe traumatic brain injury (TBI). This article provide a brief history of the process, examines challenges facing rehabilitation research in this particular area, discusses reasons for identifying prognostic data within the research context of the NIS project, and describes methodologies for use of mathematical models in predicting outcome from TBI. The literature regarding prognostic parameters in severe TBI is briefly reviewed, utilizing three broad parameter categorizations: preinjury, injury, and postinjury. The implications of this research and directions for further study within the NIS project are discussed.

Stress hormones in accident patients studied before admission to hospital

OBJECTIVE

To assess stress hormone response in traumatised patients studied at the site of injury and on their way to hospital.

METHODS

The study was prospective. Blood samples were taken from 77 patients immediately after the arrival of the emergency physician at the site of the accident (t1) and shortly before patients' admission to hospital (t2). Plasma concentrations of beta endorphin, cortisol, adrenocorticotrophic hormone (ACTH), prolactin, and growth hormone were measured.

RESULTS

Trauma in out-of-hospital patients resulted in remarkably increased concentration of growth hormone within minutes. ACTH, cortisol, and prolactin were only moderately increased. No significant correlations were found between hormone levels and blood pressure or heart rate. The plasma ACTH concentration was significantly lower before admission to hospital than immediately after the accident. Plasma cortisol, prolactin, and growth hormone concentrations were not significantly different between the two points of observation. In samples taken immediately after the accident (t1), there was a positive correlation between both beta endorphin and prolactin and the injury severity score, whereas cortisol levels were negatively correlated with injury severity score, suggesting impaired cortisol release from the adrenal cortex after severe injury. At t1 ACTH was correlated with cortisol and beta endorphin. Patients with head injuries had hormone concentrations similar to those without head injuries but with a similar injury severity score from injuries in other parts of the body.

CONCLUSIONS

Lower cortisol concentrations in the very severely injured might be due to failure of the adrenal cortex to respond normally to ACTH stimulation. Growth hormone seems to play a major role in the response to trauma, reflecting an immediate stress response.

Post-traumatic apallic syndrome following head injury. Part 1: clinical characteristics

Epidemiological studies made within the western countries indicate an incidence of 200-300 traumatic head injuries per 100 000 residents each year. Severe head injuries account for 5-25% of all head injuries; 10-14% of all severe head-injured patients develop into a vegetative state, in which a sleep-wake rhythm is apparent, but however in which there is no evidence of awakeness or reactivity to the environment. The most commonly used labels, in the German and international literature, for these patients are 'vegetative state', 'apallic syndrome' and 'coma vigile'. This clinical characterization is not sufficient. It is necessary to employ additional criteria to distinguish subsets of vegetative patients e.g. computerized tomography, magnetic resonance imaging, single photon emission tomography, electroencephalography, brainstem reflexes, evoked potentials, assessment scales, age, premorbid brain disorders. Diagnostic and prognostic parameters must form the basis for various decisions relating to patients' care and intervention.

Chronic corticosterone treatment potentiates deficits following traumatic brain injury in rats: implications for aging

The present study examined the effect of chronic corticosterone exposure on motor and cognitive deficits following traumatic brain injury (TBI). Adults rats were treated with either corticosterone acetate (15 ug/ml) added to their drinking water or vehicle (0.5% alcohol) for 3 months. Following this 3-month treatment, corticosterone-treated rats (n = 8) and vehicle-treated rats (n = 10) were injured at a mild level of fluid percussion injury (1.7-1.8 atm). Additional corticosterone-treated (n = 8) and vehicle-treated rats (n = 8) were surgically prepared for injury but were not injured. Both motor (beam balance and beam walking) and cognitive (Morris water maze) performances were assessed following injury. Motor deficits were transiently enhanced following injury in rats treated with corticosterone. Rats treated with corticosterone were also slower in learning the Morris water maze than vehicle-treated rats. These findings demonstrate that elevated corticosterone levels potentiate the behavioral deficits observed after traumatic brain injury. Applied to aging research, these results suggest that the elevated basal levels of corticosterone present in aged animals may mediate the enhanced vulnerability of aged animals to traumatic brain injury.

Abnormalities at different levels of the hypothalamic-pituitary-adrenocortical axis early after stroke

BACKGROUND AND PURPOSE

Hypercortisolism is common in stroke patients. The aim of this study was to investigate possible disturbances at different sites within the hypothalamic-pituitary-adrenal axis. We also studied possible associations between hypercortisolism and clinical manifestations of brain dysfunction.

METHODS

Patients with an acute ischemic stroke (n = 16; mean +/- SD age, 71 +/- 11 years) were compared with healthy elderly subjects (n = 9). We performed a short adrenocorticotropic hormone (ACTH) test with 0.25 mg 1-24 ACTH injected intravenously and an overnight dexamethasone suppression test with 1 mg dexamethasone given orally at 11 PM.

RESULTS

Serum cortisol levels after dexamethasone at 8 AM were significantly higher in stroke patients (p = 0.003). The area under the curve for the cortisol response to ACTH was elevated in seven (47%) of stroke patients, and the centered cumulative cortisol response was elevated in three (20%) patients. The area under the curve response correlated significantly to the presence of an acute confusional state and male sex in stroke patients (rs = 0.63 and rs = 0.62, respectively; p < 0.05), whereas the centered cumulative cortisol response diminished with increasing age (rs = -0.62; p < 0.05). Postdexamethasone cortisol levels were significantly correlated to the presence of an acute confusional state and to extensive limb paresis (rs = 0.66 and rs = 0.62, respectively; p < 0.05).

CONCLUSIONS

There are abnormalities in the cortisol axis both at the central level and at the adrenal level early after stroke. Hypercortisolism is closely associated with cognitive disturbances and extensive motor impairment.