Hypopituitarism following traumatic brain injury (TBI)

Context is key: glucocorticoid receptor and corticosteroid therapeutics in outcomes after traumatic brain injury

Traumatic brain injury (TBI) is a global health burden, and survivors suffer functional and psychiatric consequences that can persist long after injury. TBI induces a physiological stress response by activating the hypothalamic-pituitary-adrenal (HPA) axis, but the effects of injury on the stress response become more complex in the long term. Clinical and experimental evidence suggests long lasting dysfunction of the stress response after TBI. Additionally, pre- and post-injury stress both have negative impacts on outcome following TBI. This bidirectional relationship between stress and injury impedes recovery and exacerbates TBI-induced psychiatric and cognitive dysfunction. Previous clinical and experimental studies have explored the use of synthetic glucocorticoids as a therapeutic for stress-related TBI outcomes, but these have yielded mixed results. Furthermore, long-term steroid treatment is associated with multiple negative side effects. There is a pressing need for alternative approaches that improve stress functionality after TBI. Glucocorticoid receptor (GR) has been identified as a fundamental link between stress and immune responses, and preclinical evidence suggests GR plays an important role in microglia-mediated outcomes after TBI and other neuroinflammatory conditions. In this review, we will summarize GR-mediated stress dysfunction after TBI, highlighting the role of microglia. We will discuss recent studies which target microglial GR in the context of stress and injury, and we suggest that cell-specific GR interventions may be a promising strategy for long-term TBI pathophysiology.

Acute stress modulates the outcome of traumatic brain injury-associated gene expression and behavioral responses

Psychological stress and traumatic brain injury (TBI) result in long-lasting emotional and behavioral impairments in patients. So far, the interaction of psychological stress with TBI not only in the brain but also in peripheral organs is poorly understood. Herein, the impact of acute stress (AS) occurring immediately before TBI is investigated. For this, a mouse model of restraint stress and TBI was employed, and their influence on behavior and gene expression in brain regions, the hypothalamic-pituitary-adrenal (HPA) axis, and peripheral organs was analyzed. Results demonstrate that, compared to single AS or TBI exposure, mice treated with AS prior to TBI showed sex-specific alterations in body weight, memory function, and locomotion. The induction of immediate early genes (IEGs, e.g., c-Fos) by TBI was modulated by previous AS in several brain regions. Furthermore, IEG upregulation along the HPA axis (e.g., pituitary, adrenal glands) and other peripheral organs (e.g., heart) was modulated by AS-TBI interaction. Proteomics of plasma samples revealed proteins potentially mediating this interaction. Finally, the deletion of Atf3 diminished the TBI-induced induction of IEGs in peripheral organs but left them largely unaltered in the brain. In summary, AS immediately before brain injury affects the brain and, to a strong degree, also responses in peripheral organs.

Physical Health and Well-being: Updates and the Way Ahead

INTRODUCTION

The Women in Combat Summit 2021 "Forging the Future: How Women Enhance the Fighting Force" took place during February 9-11, 2021, via a virtual conference platform. The third and final day of the Summit regarded the physical health and well-being of military women and included the topics of urogenital health, nutrition and iron-deficiency anemia, unintended pregnancy and contraception, and traumatic brain injury.

MATERIALS AND METHODS

After presentations on the topics earlier, interested conference attendees were invited to participate in focus groups to discuss and review policy recommendations for physical health and well-being in military women. Discussions centered around the topics discussed during the presentations, and suggestions for future Women in Combat Summits were noted. Specifics of the methods of the Summit are presented elsewhere in this supplement.

RESULTS

We formulated research and policy recommendations for urogenital health, nutrition and iron-deficiency anemia, contraception and unintended pregnancy, and traumatic brain injury.

CONCLUSIONS

In order to continue to develop the future health of military women, health care providers, researchers, and policymakers should consider the recommendations made in this supplement as they continue to build on the state of the science and forge the future.

The dynorphin/kappa opioid receptor mediates adverse immunological and behavioral outcomes induced by repetitive blast trauma

BACKGROUND

Adverse pathophysiological and behavioral outcomes related to mild traumatic brain injury (mTBI), posttraumatic stress disorder (PTSD), and chronic pain are common following blast exposure and contribute to decreased quality of life, but underlying mechanisms and prophylactic/treatment options remain limited. The dynorphin/kappa opioid receptor (KOR) system helps regulate behavioral and inflammatory responses to stress and injury; however, it has yet to be investigated as a potential mechanism in either humans or animals exposed to blast. We hypothesized that blast-induced KOR activation mediates adverse outcomes related to inflammation and affective behavioral response.

METHODS

C57Bl/6 adult male mice were singly or repeatedly exposed to either sham (anesthesia only) or blast delivered by a pneumatic shock tube. The selective KOR antagonist norBNI or vehicle (saline) was administered 72 h prior to repetitive blast or sham exposure. Serum and brain were collected 10 min or 4 h post-exposure for dynorphin A-like immunoreactivity and cytokine measurements, respectively. At 1-month post-exposure, mice were tested in a series of behavioral assays related to adverse outcomes reported by humans with blast trauma.

RESULTS

Repetitive but not single blast exposure resulted in increased brain dynorphin A-like immunoreactivity. norBNI pretreatment blocked or significantly reduced blast-induced increase in serum and brain cytokines, including IL-6, at 4 h post exposure and aversive/anxiety-like behavioral dysfunction at 1-month post-exposure.

CONCLUSIONS

Our findings demonstrate a previously unreported role for the dynorphin/KOR system as a mediator of biochemical and behavioral dysfunction following repetitive blast exposure and highlight this system as a potential prophylactic/therapeutic treatment target.

The role of the stress system in recovery after traumatic brain injury: A tribute to Bruce S. McEwen

Traumatic brain injury (TBI) represents a major public health concern. Although the majority of individuals that suffer mild-moderate TBI recover relatively quickly, a substantial subset of individuals experiences prolonged and debilitating symptoms. An exacerbated response to physiological and psychological stressors after TBI may mediate poor functional recovery. Individuals with TBI can suffer from poor stress tolerance, impairments in the ability to evaluate stressors, and poor initiation (and cessation) of neuroendocrine stress responses, all of which can exacerbate TBI-mediated dysfunction. Here, we pay tribute to the pioneering neuroendocrinologist Dr. Bruce McEwen by discussing the ways in which his work on stress physiology and allostatic loading impacts the TBI patient population both before and after their injuries. Specifically, we will discuss the modulatory role of hypothalamic-pituitary-adrenal axis responses immediately after TBI and later in recovery. We will also consider the impact of stressors and stress responses in promoting post-concussive syndrome and post-traumatic stress disorders, two common sequelae of TBI. Finally, we will explore the role of early life stressors, prior to brain injuries, as modulators of injury outcomes.

Bidirectional Brain-Systemic Interactions and Outcomes After TBI

Traumatic brain injury (TBI) is a debilitating disorder associated with chronic progressive neurodegeneration and long-term neurological decline. Importantly, there is now substantial and increasing evidence that TBI can negatively impact systemic organs, including the pulmonary, gastrointestinal (GI), cardiovascular, renal, and immune system. Less well appreciated, until recently, is that such functional changes can affect both the response to subsequent insults or diseases, as well as contribute to chronic neurodegenerative processes and long-term neurological outcomes. In this review, we summarize evidence showing bidirectional interactions between the brain and systemic organs following TBI and critically assess potential underlying mechanisms.

Mild and Moderate Traumatic Brain Injury and Repeated Stress Affect Corticosterone in the Rat

Traumatic brain injury (TBI) survivors suffer from a range of morbidities, including post-traumatic endocrinopathies that can cause physical and mental changes in patients, greatly compromising quality of life. This study tested the hypothesis that mild and moderate diffuse TBI leads to chronic deficiencies in corticosterone (CORT) regulation following repeated exposure to restraint stress over time. Young adult male rats (n = 9–11/group) were subjected to mild or moderate TBI induced by midline fluid percussion injury (mFPI) or control sham surgery. At 6 and 24 h post-injury, both mild and moderate TBI resulted in elevated resting plasma CORT levels compared with uninjured shams. Independent of TBI severity, all rats had lower resting plasma CORT levels at 7, 14, 28, and 54 days post-injury compared with pre-surgery baseline CORT. Circulating levels of CORT were also evaluated under restraint stress and in response to dexamethasone (DEX), a synthetic glucocorticoid. Independent of TBI severity, restraint stress elevated CORT at 30, 60, and 90 min post-stressor initiation at all post-injury time-points. A blunted CORT response to restraint stress was observed with lower CORT levels after restraint at 28 and 54 days compared with 7 days post-injury (DPI), indicative of habituation to the stressor. A high dose of DEX lowered CORT levels at 90 min post-restraint stress initiation compared with low-dose DEX, independent of TBI severity. These results support TBI-induced CORT dysregulation at acute time-points, but additional studies that investigate the onset and progression of endocrinopathies, controlling for habituation to repeated restraint stress, are needed to inform the diagnosis and treatment of such morbidities in TBI survivors.

Sleep Disruption Exacerbates and Prolongs the Inflammatory Response to Traumatic Brain Injury

Traumatic brain injury (TBI) alters stress responses, which may influence neuroinflammation and behavioral outcome. Sleep disruption (SD) is an understudied post-injury environmental stressor that directly engages stress-immune pathways. Thus, we predicted that maladaptive changes in the hypothalamic-pituitary-adrenal (HPA) axis after TBI compromise the neuroendocrine response to SD and exacerbate neuroinflammation. To test this, we induced lateral fluid percussion TBI or sham injury in female and male C57BL/6 mice aged 8-10 weeks that were then left undisturbed or exposed to 3 days of transient SD. At 3 days post-injury (DPI) plasma corticosterone (CORT) was reduced in TBI compared with sham mice, indicating altered HPA-mediated stress response to SD. This response was associated with approach-avoid conflict behavior and exaggerated cortical neuroinflammation. Post-injury SD specifically enhanced neutrophil trafficking to the injured brain in conjunction with dysregulated aquaporin-4 (AQP4) polarization. Delayed and persistent effects of post-injury SD were determined 4 days after SD concluded at 7 DPI. SD prolonged anxiety-like behavior regardless of injury and was associated with increased cortical Iba1 labeling in both sham and TBI mice. Strikingly, TBI SD mice displayed an increased number of CD45+ cells near the site of injury, enhanced cortical glial fibrillary acidic protein (GFAP) immunolabeling, and persistent expression of Trem2 and Tlr4 7 DPI compared with TBI mice. These results support the hypothesis that post-injury SD alters stress-immune pathways and inflammatory outcomes after TBI. These data provide new insight to the dynamic interplay between TBI, stress, and inflammation.

Stress reactivity after traumatic brain injury: implications for comorbid post-traumatic stress disorder

Most people have or will experience traumatic stress at some time over the lifespan, but only a subset of traumatized individuals develop post-traumatic stress disorder (PTSD). Clinical research supports high rates of traumatic brain injury (TBI)-PTSD comorbidity and demonstrates TBI as a significant predictor of the development of PTSD. Biological factors impacted following brain injury that may contribute to increased PTSD risk are unknown. Heightened stress reactivity and dysregulated hypothalamic-pituitary-adrenal (HPA) axis function are common to both TBI and PTSD, and affect amygdalar structure and function, which is implicated in PTSD. In this review, we summarize a growing body of literature that shows HPA axis dysregulation, as well as enhanced fear and amygdalar function after TBI. We present the hypothesis that altered stress reactivity as a result of brain injury impacts the amygdala and defense systems to be vulnerable to increased fear and PTSD development from traumatic stress. Identifying biological mechanisms that underlie this vulnerability, such as dysregulated HPA axis function, may lead to better targeted treatments and preventive measures to support psychological health after TBI.

The history of pituitary dysfunction after traumatic brain injury

PURPOSE

To estimate the total number of articles on traumatic brain injury (TBI)-related hypopituitarism and patients (including children and adolescents) with such disorder that were published until now, particularly after the author's review published on April 2000.

METHODS

Review of the literature retrievable on PubMed.

RESULTS

TBI-related hypopituitarism accounts for 7.2% of the whole literature on hypopituitarism published during the 18 years and half between May 2000 and October 2018. As a result, the total number of patients with TBI-related hypopituitarism now approximates 2200. A number of patients, both adults and children, continue to be published as case reports. Articles, including reviews and guidelines, have been published in national languages in order to maximize locally the information on TBI-related hypopituitarism. TBI-related hypopituitarism has been also studied in animals (rodents, cats and dogs).

CONCLUSIONS

The interest for the damage suffered by anterior pituitary as a result of TBI continues to remain high both in the adulthood and childhood.

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.

Differential Responses of the HPA Axis to Mild Blast Traumatic Brain Injury in Male and Female Mice

Traumatic brain injury (TBI) affects 10 million people worldwide, annually. TBI is linked to increased risk of psychiatric disorders. TBI, induced by explosive devices, has a unique phenotype. Over one-third of people exposed to blast-induced TBI (bTBI) have prolonged neuroendocrine deficits, shown by anterior pituitary dysfunction. Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is linked to increased risk for psychiatric disorders. Not only is there limited information on how the HPA axis responds to mild bTBI (mbTBI), sex differences are understudied. We examined central and peripheral HPA axis reactivity, 7 to 10 days after mbTBI in male and female mice. Males exposed to mbTBI had increased restraint-induced serum corticosterone (CORT), but attenuated restraint-induced corticotropin-releasing factor (CRF)/c-Fos-immunoreactivity (ir) in the paraventricular nucleus of the hypothalamus (PVN). Females displayed an opposite response, with attenuated restraint-induced CORT and enhanced restraint-induced PVN CRF/c-Fos-ir. We examined potential mechanisms underlying this dysregulation and found that mbTBI did not affect pituitary (pro-opiomelanocortin and CRF receptor subtype 1) or adrenal (11β-hydroxylase, 11β-dehydrogenase 1, and melanocortin 2 receptor) gene expression. mbTBI did not alter mineralocorticoid or glucocorticoid gene expression in the PVN or relevant limbic structures. In females, but not males, mbTBI decreased c-Fos-ir in non-neuroendocrine (presumably preautonomic) CRF neurons in the PVN. Whereas we demonstrated a sex-dependent link to stress dysregulation of preautonomic neurons in females, we hypothesize that mbTBI may disrupt limbic pathways involved in HPA axis coordination in males. Overall, mbTBI altered the HPA axis in a sex-dependent manner, highlighting the importance of developing therapies to target individual strategies that males and females use to cope with mbTBI.

Sport Concussion and the Female Athlete

Sport concussion (SC) has emerged as a major health concern in the medical community and general public owing to increased research and media attention, which has primarily focused on male athletes. Female athletes have an equal, if not increased, susceptibility to SC. An ever-growing body of research continues to compare male and female athletes in terms of SC before and after an injury. Clinicians must be cognizant of this literature to make evidence-based clinical decision when providing care to female athletes and discern between dated and/or unsupported claims in terms of SC.

Functional Changes after Recombinant Human Growth Hormone Replacement in Patients with Chronic Traumatic Brain Injury and Abnormal Growth Hormone Secretion

We explored the effects of recombinant human growth hormone (rhGH) replacement on physical and cognitive functioning in subjects with a moderate-to-severe traumatic brain injury (TBI) with abnormal growth hormone (GH) secretion. Fifteen individuals who sustained a TBI at least 12 months prior to study enrollment were identified as having abnormal GH secretion by glucagon stimulation testing (maximum GH response less than 8 ng/mL). Peak cardiorespiratory capacity, body composition, and muscle force testing were assessed at baseline and one year after rhGH replacement. Additionally, standardized neuropsychological tests that assess memory, processing speed, and cognitive flexibility, as well as self-report inventories related to depression and fatigue, were administered at baseline and 1 year after rhGH replacement. Comparison tests were performed with proper post hoc analyses. All analyses were carried out at α < 0.05. Peak O₂ consumption, peak oxygen pulse (estimate of cardiac stroke volume), and peak ventilation all significantly increased (p < 0.05). Maximal isometric and isokinetic force production were not altered. Skeletal muscle fatigue did not change but the perceptual rating of fatigue was reduced by ∼25% (p = 0.06). Cognitive performance did not change significantly over time, whereas self-reported symptoms related to depression and fatigue significantly improved. The observed changes suggest that rhGH replacement has a positive impact on cardiorespiratory fitness and a positive impact on perceptual fatigue in survivors of TBI with altered GH secretion.

Post-traumatic hypopituitarism: report of a child case

Case

We report a case of post‐traumatic hypopituitarism in a 9‐year‐old boy who was injured in a car accident.

Outcome

Post‐traumatic hypopituitarism might be caused by moderate to severe head trauma, and while this possibility has recently drawn attention in adults, few reports are available regarding children. Our patient experienced head and facial injury, resulting in post‐traumatic hypopituitarism. Six hours after injury he suffered from diabetes insipidus and hormone replacement therapy was started. On day 12 he underwent facial fracture reduction under general anesthesia. On day 24 he was discharged from the hospital. One year after the injury, secretory function and water dehydration tests suggested the possibility of post‐traumatic hypopituitarism.

Conclusion

We experienced a child case of post‐traumatic hypopituitarism. Emergency physicians should pay attention to the possibility of post‐traumatic hypopituitarism in cases of traumatic brain injury.

Differences according to Sex in Sociosexuality and Infidelity after Traumatic Brain Injury

OBJECTIVE

To explore differences according to sex in sociosexuality and infidelity in individuals with TBI and in healthy controls.

PARTICIPANTS

Forty-two individuals with mild, moderate, and severe TBI having completed a postacute TBI rehabilitation program, at least six months after injury, and 47 healthy controls.

MAIN MEASURES

Sociosexual Orientation Inventory-Revised (SOI-R) and Attitudes toward Infidelity Scale.

RESULTS

Overall, men score significantly higher than women in sociosexuality. However, there was a nonsignificant trend towards a reduction of sociosexuality levels in men with TBI. Infidelity levels were comparable in healthy controls and individuals with TBI. In individuals with TBI, less acceptance of infidelity was significantly associated with an unrestricted sociosexual orientation, but not in healthy controls.

CONCLUSIONS

As documented in previous cross-cultural studies, men have higher levels of sociosexuality than women. However, men with TBI showed a tendency towards the reduction of sociosexuality. The possibility of a latent explanatory variable is suggested (e.g., post-TBI neuroendocrinological changes). TBI does not seem to have an impact on infidelity, but individuals with TBI who express less acceptance of infidelity also report a more promiscuous mating strategy regarding their behavior, attitudes, and desire. Theoretical implications are discussed in terms of evolutionary theories of human sexuality and neuropsychology.

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.

Impaired Pituitary Axes Following Traumatic Brain Injury

Pituitary dysfunction following traumatic brain injury (TBI) is significant and rarely considered by clinicians. This topic has received much more attention in the last decade. The incidence of post TBI anterior pituitary dysfunction is around 30% acutely, and declines to around 20% by one year. Growth hormone and gonadotrophic hormones are the most common deficiencies seen after traumatic brain injury, but also the most likely to spontaneously recover. The majority of deficiencies present within the first year, but extreme delayed presentation has been reported. Information on posterior pituitary dysfunction is less reliable ranging from 3%-40% incidence but prospective data suggests a rate around 5%. The mechanism, risk factors, natural history, and long-term effect of treatment are poorly defined in the literature and limited by a lack of standardization. Post TBI pituitary dysfunction is an entity to recognize with significant clinical relevance. Secondary hypoadrenalism, hypothyroidism and central diabetes insipidus should be treated acutely while deficiencies in growth and gonadotrophic hormones should be initially observed.

Adrenal inhibition following a single dose of etomidate in intubated traumatic brain injury victims

Background:

Etomidate is frequently used to intubate traumatic brain injury (TBI) victims, even though it has been linked to adrenal insufficiency (AI) in some populations. Few studies have explored the risk of prolonged etomidateinduced AI among TBI victims.

Objective:

To determine the risk and the length of AI induced by etomidate in patients intubated for moderate and severe TBI.

Methods:

Participants in this observational study were moderate to severe intubated TBI victims aged ≥ 16 years. The anesthetic used (etomidate versus others) was determined solely by the treating emergency physician. Adrenocorticotropic hormone (ACTH) stimulation tests (250 µg) were performed 24, 48, and 168 hours after intubation. AI was defined as an increase in serumcortisol 1 hour post–ACTH test (delta cortisol) of less than 248.4 nmol/L.

Results:

Forty subjects (participation 42.6%) underwent ACTH testing. Fifteen received etomidate, and 25 received another anesthetic. There were no statistically significant differences between groups as to the cumulative incidence of AI at any measurement time. However, at 24 hours, exploratory post hoc analyses showed a significant decrease in delta cortisol (adjusted means: etomidate group: 305.1 nmol/L, 95% CI 214.7–384.8 versus other anesthetics: 500.5 nmol/L, 95% CI 441.8–565.7). This decrease was not present at 48 and 168 hours.

Conclusion:

In TBI victims, although a single dose of etomidate does not increase the cumulative incidence of AI as defined, it seems to decrease the adrenal response to an ACTH test for 24 hours. The clinical impacts of this finding remain to be determined.

Role of hormonal levels on hospital mortality for male patients with severe traumatic brain injury

INTRODUCTION

Changes in hormone blood levels during the acute phase of traumatic brain injury (TBI) have been described in the literature. The objective was to investigate the association among several hormones plasma levels in the acute phase of severe TBI and the hospital mortality rate of male patients.

METHODS

The independent association among plasma levels of TSH, LH, FSH, GH, free T4, cortisol, IGF-1 and total testosterone was measured 10 hours and 30 hours after severe TBI and the hospital mortality of 60 consecutive male patients was evaluated.

RESULTS

At least one hormonal level abnormality was demonstrated in 3.6-73.1% of patients. The multiple logistic regressions showed a trend for an independent association among hospital mortality and normal or elevated LH levels measured at 10 hours (OR = 3.7, 95% CI = 0.8-16.3, p = 0.08) and 30 hours (OR = 3.9, 95% CI = 0.9-16.7, p = 0.06). Admission with abnormal pupils and a lower Glasgow Coma Score also were independently associated with hospital mortality.

CONCLUSION

The hormonal changes are frequent in the acute phase of severe TBI. The hormones plasma levels, excepting the LH, are not highly consistent with the hospital mortality of male patients.

Hypothalamic-pituitary dysfunction following traumatic brain injury affects functional improvement during acute inpatient rehabilitation

OBJECTIVE

To evaluate the occurrence of hypothalamic-pituitary dysfunction following a traumatic brain injury (TBI) and to determine its effect on functional improvement in acute inpatient rehabilitation.

METHODS

A retrospective chart review identified male patients with a primary diagnosis of TBI with or without a skull fracture, an onset date within 6 months prior to admission, and were 16 years of age or older. The percentage of individuals in this population with abnormal hormone levels was determined on the basis of the established normal reference range for each hormone assay. The functional independence measure, which assesses functional outcomes in acute inpatient rehabilitation, was used to examine the relationship between hormone levels and functional improvement.

RESULTS

Hypothalamic-pituitary dysfunction was identified in nearly 70% of men following TBI. Hypogonadism, or low testosterone levels, was observed in 66% of the patients, followed by low levels of free T4 in 46% and low levels of insulin growth factor-1 in 26% of patients. Hypopituitarism associated with impaired functional recovery. Specifically, the functional independence measure change per day was significantly lower in patients with low levels of testosterone and insulin growth factor-1.

CONCLUSIONS

These findings suggest the importance of testosterone and insulin growth factor-1 activity in the early stages of physical and cognitive rehabilitation.

Hormonal dysfunction in neurocritical patients

PURPOSE OF REVIEW

Acute brain injury results in widespread systemic endocrine dysfunction and affects how we care for patients. We review the existing literature on incidence, type and duration of endocrine dysfunction with special focus on the pituitary dependent function.

RECENT FINDINGS

Acute studies document widespread alterations of the hypothalamic-pituitary-adrenal axis, disruption of the anterior hypothalamus related hormones, and alteration of regulation of sodium and fluid balance. Diagnostic testing and therapeutic intervention are outlined in this review. Relative adrenal insufficiency and cerebral salt wasting are the two main forms of endocrine dysfunction in neurocritical care patients.

SUMMARY

Surveillance for endocrine dysfunction and early treatment with hormonal replacement may be life-saving in neurologic critically ill patients.

Restoration of neuroendocrine stress response by glucocorticoid receptor or GABA(A) receptor antagonists after experimental traumatic brain injury

We previously reported that traumatic brain injury (TBI) produced by moderate controlled cortical impact (CCI) attenuates the stress response of the hypothalamic-pituitary-adrenal (HPA) axis between 21 and 70 days postinjury and enhances the sensitivity of the stress response to glucocorticoid negative feedback. In the current study, we investigated two possible mechanisms for the CCI-induced attenuation of the HPA stress response-i.e, glucocorticoid receptor (GR) and GABA-mediated inhibition of the HPA axis, with the GR antagonist, mifepristone (RU486), or the GABA(A)-receptor antagonist, bicuculline. In addition, we examined the effect of moderate CCI on GR and inhibitory neurons histologically in subfields of the hippocampus, medial prefrontal cortex, and amygdala. We show that at 30-min after onset of restraint stress, GR as well as GABA antagonism with MIFE or BIC, respectively, reversed the attenuating effects of moderate CCI on the stress-induced HPA response. Our histological results demonstrate that moderate CCI led to a loss of glutamic acid decarboxylase 67 or parvalbumin-positive inhibitory neurons within regions of the hippocampus and amygdala but did not lead to significant increases in GR in these regions. These findings indicate that suppression of the stress-induced HPA response after moderate CCI is mediated by the inhibitory actions of both GR and GABA, with a corresponding loss of inhibitory neurons within brain regions with neural pathways affecting limbic stress-integrative pathways.

Hypopituitarism and sphenoid surgery

A middle-aged white man underwent sphenoid and ethmoid surgery for rhinitis with polyposis. Within days, he developed severe fatigue, myalgias and arthralgias. Initial testing demonstrated central hypogonadism, followed by a low normal insulin-like growth factor-1 and an abnormal L-dopamine growth hormone stimulation test result. As years past, the patient would have such recurrent symptoms when ill with the addition of nausea and vomiting. Testing, 7 years after his initial surgery, confirmed inappropriate thyroid and cortisol responses. His clinical symptoms have resolved with appropriate medical therapy. A review of the literature demonstrated no descriptions of hypopituitarism from sphenoid surgery.

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.

Neuroendocrine dysfunctions and their consequences following traumatic brain injury

Posttraumatic hypopituitarism is of major public health importance because it is more prevalent than previously thought. The prevalence of hypopituitarism in children with traumatic brain injury is unknown. Most cases of posttraumatic hypopituitarism remain undiagnosed and untreated in the clinical practice, and it may contribute to the severe morbidity seen in patients with traumatic brain injury. In the acute phase of brain injury, the diagnosis of adrenal insufficiency should not be missed. Determination of morning serum cortisol concentration is mandatory, because adrenal insufficiency can be life threatening. Morning serum cortisol lower than 200 nmol/L strongly suggests adrenal insufficiency. A complete hormonal investigation should be performed after one year of the trauma. Isolated growth hormone deficiency is the most common deficiency after traumatic brain injury. Sports-related chronic repetitive head trauma (because of boxing, kickboxing, football and ice hockey) may also result in hypopituitarism. Close co-operation between neurosurgeons, endocrinologists, rehabilitation physicians and representatives of other disciplines is important to provide better care for these patients. Orv. Hetil., 2012, 153, 927–933.

Effect of growth hormone replacement therapy on cognition after traumatic brain injury

Traumatic brain injury (TBI) is a major public health issue, and yet medical science has little to offer for the persistent symptoms that prevent many of these individuals from fully re-entering society. Post-traumatic hypopituitarism, and specifically growth hormone deficiency (GHD), has been found in a large percentage of individuals with chronic moderate to severe TBI. Presently, there are no published treatment studies of hormone replacement in this population. In this study, 83 subjects with chronic TBI were screened for hypopituitarism. Forty-two subjects were found to have either GHD or GH insufficiency (GHI), of which 23 agreed to be randomized to either a year of GH replacement or placebo. All subjects completed the study with no untoward side effects from treatment. A battery of neuropsychological tests and functional measures were administered before and after treatment. Improvement was seen on the following tests: Dominant Hand Finger Tapping Test, Wechsler Adult Intelligence Scale III-Information Processing Speed Index, California Verbal Learning Test II, and the Wisconsin Card Sorting Test (executive functioning). The findings of this pilot study provide preliminary evidence suggesting that some of the cognitive impairments observed in persons who are GHD/GHI after TBI may be partially reversible with appropriate GH replacement therapy.

Injury severity differentially alters sensitivity to dexamethasone after traumatic brain injury

We have reported differential short- and long-term dysregulation of the neuroendocrine stress response after traumatic brain injury (TBI) produced by controlled cortical impact (CCI). We have now investigated three possible mechanisms for this TBI-induced dysregulation: (1) effects on the sensitivity of negative-feedback systems to glucocorticoids; (2) effects on the sensitivity of pituitary corticotrophs to corticotropin-releasing hormone (CRH); and (3) effects on neuronal loss in the hilar region of the dentate gyrus and in the CA3b layer of the dorsal hippocampus. TBI was induced to the left parietal cortex in adult male rats with a pneumatic piston, at two different impact velocities and compression depths, to produce either moderate or mild CCI. At 7 and 35 days after surgery, the rats were injected SC with the synthetic glucocorticoid analog dexamethasone (DEX; 0.01, 0.10, or 1.00 mg/kg) or saline, and 2 h later were subjected to 30 min of restraint stress and tail vein blood collection. Whereas all doses of DEX suppressed corticosterone (CORT) and adrenocorticotropic hormone (ACTH) responses to stress on both days, CORT and ACTH were significantly more suppressed after 0.01 mg/kg DEX in the moderate TBI group than in the mild TBI or sham groups. At both 7 and 35 days post-TBI, CRH (1.0 and 10.0 microg/kg IP) stimulated CORT and ACTH in all rats, regardless of injury condition. Hippocampal cell loss was greatest at 48 days after moderate TBI. Enhanced sensitivity to glucocorticoid negative feedback and greater hippocampal cell loss, but not altered pituitary responses to CRH, contribute to the short- and long-term attenuation of the neuroendocrine stress response following moderate TBI. The role of TBI-induced alterations in glucocorticoid receptors in limbic system sites in enhanced glucocorticoid feedback sensitivity requires further investigation.

Hypopituitarism following traumatic brain injury: prevalence is affected by the use of different dynamic tests and different normal values

OBJECTIVE

Traumatic brain injury (TBI) has emerged as an important cause of hypopituitarism. However, considerable variations in the prevalence of hypopituitarism are reported. These can partly be explained by severity of trauma and timing of hormonal evaluation, but may also be dependent on endocrine tests and criteria used for diagnosis of hypopituitarism.

METHODS

Systematic review of studies reporting prevalence of hypopituitarism in adults >or=1 year after TBI focusing on used (dynamic) tests and biochemical criteria.

RESULTS

We included data from 14 studies with a total of 931 patients. There was considerable variation in definition of hypopituitarism. Overall, reported prevalences of severe GH deficiency varied between 2 and 39%. Prevalences were 8-20% using the GHRH-arginine test (cutoff <9 microg/l), 11-39% using the glucagon test (cutoff 1-5 microg/l), 2% using the GHRH test (no cutoff), and 15-18% using the insulin tolerance test (ITT; cutoff <3 microg/l). Overall, the reported prevalence of secondary adrenal insufficiency had a broad range from 0 to 60%. This prevalence was 0-60% with basal cortisol (cutoff <220 or <440 nmol/l), 7-19% using the ACTH test, and 5% with the ITT as first test (cutoff <500 or <550 nmol/l). Secondary hypothyroidism was present in 0-19% (free thyroxine) or 5-15% (thyroid-releasing hormone stimulation). Secondary hypogonadism was present in 0-29%.

CONCLUSION

The reported variations in the prevalence rates of hypopituitarism after TBI are in part caused by differences in definitions, endocrine assessments of hypopituitarism, and confounding factors. These methodological issues prohibit simple generalizations of results of original studies on TBI-associated hypopituitarism in the perspective of meta-analyses or reviews.

Endocrine consequences of adult traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) is the most common cause of death and disability in young adults living in industrialised countries. Over the last few years, there has been an increasing awareness that hypopituitarism can complicate TBI in a significant proportion of survivors: at least 25% of TBI survivors develop one or more pituitary hormone deficiencies. This remarkably high frequency has changed the traditional concept that hypopituitarism was a rare complication of TBI and suggests that most cases of posttraumatic hypopituitarism remain undiagnosed and untreated in clinical practice. It is therefore reasonable to infer that posttraumatic hypopituitarism may make an important contribution to the high rates of physical and neuropsychiatric morbidity in patients with head injury.

CONCLUSIONS

There is clearly a need for identification as well as appropriate and timely management of hormone deficiencies in TBI patients to reduce morbidity, aid recovery and rehabilitation and avoid the long-term complications of pituitary failure.