Anterior pituitary dysfunction in moderate-to-severe chronic traumatic brain injury patients and the influence on functional outcome

Neuroendocrine challenges and clinical outcomes in men with chronic traumatic brain injury: a cross-sectional study

BACKGROUND AND OBJECTIVES

Marked changes in the hypothalamic-pituitary axis have been documented in patients with traumatic brain injury (TBI). These enduring endocrine challenges could significantly influence the physical and psychological outcomes thereby impacting overall recovery. This study aimed to determine the prevalence and types of endocrine dysfunction in men with chronic TBI and to determine the association of endocrine dysfunction with clinical outcomes.

METHODOLOGY

A cross-sectional study that included male participants of 25-45 years (N = 66) with moderate to severe TBI within 6-24 months of injury. Serum Cortisol, Free T4, TSH, Luteinizing hormone, Testosterone, ACTH, Prolactin and IGF-1 were assessed. Glasgow Outcome Scale Extended (GOS-E) and Modified Barthel Index (MBI) scores were also assessed in them.

RESULTS

The study cohort comprised male patients with a mean ± age of 32.8 ± 5.7 years. Low IGF-1 levels were most commonly encountered, followed by hypogonadism. Hypopituitarism was present in 56.1%. The proportion of hypogonadism was significantly higher in the group with moderate-total dependence (13/26) as compared to the functionally independent (8/40) group (50% vs. 20%; P = 0.011). Univariate and multivariate logistic regression analysis was used to determine the factors associated with hypopituitarism, revealing that severity of injury (OR = 2.6;) and GOS-E (OR = 3.1) were significant (P < 0.10) on univariate analysis.

CONCLUSIONS

This study emphasizes the need to screen TBI patients for neuroendocrine dysfunction during the chronic phases and to establish screening criteria.

Acute neuroendocrine changes after traumatic brain injury

Introduction

Post-traumatic hypopituitarism (PTHP) is a significant, but often neglected consequence of traumatic brain injury (TBI).

Research question

We aimed to provide a comprehensive overview of epidemiology, pathophysiology, clinical features and diagnostic approaches of PTHP.

Materials and methods

MEDLINE, EMBASE, Cochrane Library and Web of Science were searched. 45 articles of human studies evaluating acute endocrine changes following mild, moderate and severe TBI were selected.

Results

Severity of TBI seems to be the most important risk factor of PTHP. Adrenal insufficiency (AI) was present in 10% of TBI patients (prevalence can be as high as 50% after severe TBI), and hypocortisolemia is a predictor of mortality and long-term hypopituitarism. Suppression of the thyroid axis in 2-33% of TBI patients may be an independent predictor of adverse neurological outcome, as well. 9-36% of patients with severe TBI exhibit decreased function of the somatotrophic axis with a divergent effect on the central nervous system. Arginine-Vasopressin (AVP) deficiency is present in 15-51% of patients, associated with increased mortality and unfavorable outcome. Due to shear and injury of the stalk hyperprolactinemia is relatively common (2-50%), but it bears little clinical significance. Sex hormone levels remain within normal values.

Discussion and conclusion

PTHP occurs frequently after TBI, affecting various axis and determining patients' outcome. However, evidence is scarce regarding exact epidemiology, diagnosis, and effective clinical application of hormone substitution. Future studies are needed to identify patients at-risk, determine the optimal timing for endocrine testing, and refine diagnostic and treatment approaches to improve outcome.

Epidemiology of Male Hypogonadism

The epidemiology of male hypogonadism has been understudied. Of the known causes of endogenous androgen deficiency, only Klinefelter syndrome is common with a likely population prevalence of greater than 5:10,000 men (possibly as high as 10-25:10,000). Mild traumatic injury might also be a common cause of androgen deficiency (prevalence 5-10:10,000 men), but large, long-term studies must be completed to confirm this prevalence estimation that might be too high. The classic causes of male androgen deficiency-hyperprolactinemia, pituitary macroadenoma, endogenous Cushing syndrome, and iron overload syndrome-are rare (prevalence < 10,000 men).

Neuroinflammation and Hypothalamo-Pituitary Dysfunction: Focus of Traumatic Brain Injury

The incidence of traumatic brain injury (TBI) has increased over the last years with an important impact on public health. Many preclinical and clinical studies identified multiple and heterogeneous TBI-related pathophysiological mechanisms that are responsible for functional, cognitive, and behavioral alterations. Recent evidence has suggested that post-TBI neuroinflammation is responsible for several long-term clinical consequences, including hypopituitarism. This review aims to summarize current evidence on TBI-induced neuroinflammation and its potential role in determining hypothalamic-pituitary dysfunctions.

Insights into non-classic and emerging causes of hypopituitarism

Hypopituitarism is defined as one or more partial or complete pituitary hormone deficiencies, which are related to the anterior and/or posterior gland and can have an onset in childhood or adulthood. The most common aetiology is a sellar or suprasellar lesion, often an adenoma, which causes hypopituitarism due to tumour mass effects, or the effects of surgery and/or radiation therapy. However, other clinical conditions, such as traumatic brain injury, and autoimmune and inflammatory diseases, can result in hypopituitarism, and there are also genetic causes of hypopituitarism. Furthermore, the use of immune checkpoint inhibitors to treat cancer is increasing the risk of hypopituitarism, with a pattern of hormone defects that is different from the classic patterns and depends on mechanisms that are specific for each drug. Moreover, autoantibody production against the pituitary and hypothalamus has been demonstrated in studies investigating the development or worsening of some cases of hypopituitarism. Finally, evidence suggests that posterior pituitary damage can affect oxytocin secretion. The aim of this Review is to summarize current knowledge on non-classic and emerging causes of hypopituitarism, so as to help clinicians improve early identification, avoid life-threatening events and improve the clinical care and quality of life of patients at risk of hypopituitarism.

Traumatic Brain Injury as Frequent Cause of Hypopituitarism and Growth Hormone Deficiency: Epidemiology, Diagnosis, and Treatment

Traumatic brain injury (TBI)-related hypopituitarism has been recognized as a clinical entity for more than a century, with the first case being reported in 1918. However, during the 20^th century hypopituitarism was considered only a rare sequela of TBI. Since 2000 several studies strongly suggest that TBI-mediated pituitary hormones deficiency may be more frequent than previously thought. Growth hormone deficiency (GHD) is the most common abnormality, followed by hypogonadism, hypothyroidism, hypocortisolism, and diabetes insipidus. The pathophysiological mechanisms underlying pituitary damage in TBI patients include a primary injury that may lead to the direct trauma of the hypothalamus or pituitary gland; on the other hand, secondary injuries are mainly related to an interplay of a complex and ongoing cascade of specific molecular/biochemical events. The available data describe the importance of GHD after TBI and its influence in promoting neurocognitive and behavioral deficits. The poor outcomes that are seen with long standing GHD in post TBI patients could be improved by GH treatment, but to date literature data on the possible beneficial effects of GH replacement therapy in post-TBI GHD patients are currently scarce and fragmented. More studies are needed to further characterize this clinical syndrome with the purpose of establishing appropriate standards of care. The purpose of this review is to summarize the current state of knowledge about post-traumatic GH deficiency.

Neuroendocrine Dysfunction in the Acute Setting of Penetrating Brain Injury: A Systematic Review

BACKGROUND

Data on neuroendocrine dysfunction (NED) in the acute setting of penetrating brain injury (PBI) are scarce, and the clinical approach to diagnosis and treatment remains extrapolated from the literature on blunt head trauma.

METHODS

Three databases were searched (PubMed, Scopus, and Cochrane). Risk of bias was computed using the Newcastle-Ottawa Scale, or the methodological quality of case series and case reports, as indicated. This systematic review was registered in PROSPERO (42020172163).

RESULTS

Six relevant studies involving 58 patients with PBI were included. Two studies were prospective cohort analyses, whereas 4 were case reports. The onset of NED was acute in all studies, by the first postinjury day. Risk factors for NED included worse injury severity and the presence of cerebral edema on imaging. Dysfunction of the anterior hypophysis involved the hypothalamic-pituitary-thyroid axis, treated with hormonal replacement, and hypocortisolism, treated with hydrocortisone. The prevalence of central diabetes insipidus was up to 41%. Most patients showed persistent NED months after injury. In separate reports, diabetes insipidus and hypocortisolism showed an association with higher mortality. The available literature for this review is poor, and the studies included had overall low quality with high risk of bias.

CONCLUSIONS

NED seems to be prevalent in the acute phase of PBI, equally involving both anterior and posterior hypophysis. Despite a potential association between NED and mortality, data on the optimal management of NED are limited. This situation defines the need for prospective studies to better characterize the clinical features and optimal therapeutic interventions for NED in PBI.

Traumatic brain injuries induced pituitary dysfunction: a call for algorithms

Traumatic brain injury affects many people each year, resulting in a serious burden of devastating health consequences. Motor-vehicle and work-related accidents, falls, assaults, as well as sport activities are the most common causes of traumatic brain injuries. Consequently, they may lead to permanent or transient pituitary insufficiency that causes adverse changes in body composition, worrisome metabolic function, reduced bone density, and a significant decrease in one's quality of life. The prevalence of post-traumatic hypopituitarism is difficult to determine, and the exact mechanisms lying behind it remain unclear. Several probable hypotheses have been suggested. The diagnosis of pituitary dysfunction is very challenging both due to the common occurrence of brain injuries, the subtle character of clinical manifestations, the variable course of the disease, as well as the lack of proper diagnostic algorithms. Insufficiency of somatotropic axis is the most common abnormality, followed by presence of hypogonadism, hypothyroidism, hypocortisolism, and diabetes insipidus. The purpose of this review is to summarize the current state of knowledge about post-traumatic hypopituitarism. Moreover, based on available data and on our own clinical experience, we suggest an algorithm for the evaluation of post-traumatic hypopituitarism. In addition, well-designed studies are needed to further investigate the pathophysiology, epidemiology, and timing of pituitary dysfunction after a traumatic brain injury with the purpose of establishing appropriate standards of care.

Long-term neuroendocrine consequences of traumatic brain injury and strategies for management

Introduction: Traumatic brain injuries (TBI) are reported to cause neuroendocrine impairment with a prevalence of 15% with confirmatory testing. Pituitary dysfunction (PD) may have detrimental effects on vital parameters as well as on body composition, cardiovascular functions, cognition, and quality of life. Therefore, much effort has been made to identify predictive factors for post-TBI PD and various screening strategies have been offered.Areas covered: We searched PubMed and reviewed the recent data on clinical perspectives and long-term outcomes as well as predictive factors and screening modalities of post-TBI PD. Inconsistencies in the literature are overviewed and new areas of research are discussed.Expert opinion: Studies investigating biomarkers that will accurately predict TBI patients with a high risk of PD are generally pilot studies with a small number of participants. Anti-pituitary and anti-hypothalamic antibodies, neural proteins, micro-RNAs are promising in this field. As severity of TBI has been the most commonly associated risk factor for post-TBI PD, we suggest prospective screening based on severity of head trauma until new evidence emerges. There is also a need for more studies investigating the clinical effects of hormone replacement in TBI patients with PD.

Prevalence of Anterior Pituitary Dysfunction Twelve Months or More following Traumatic Brain Injury in Adults: A Systematic Review and Meta-Analysis

The objective of this study is to systematically review clinical studies that have reported on the prevalence of chronic post-traumatic brain injury anterior pituitary dysfunction (PTPD) 12 months or more following traumatic brain injury (TBI). We searched Medline, Embase, and PubMed up to April 2017 and consulted bibliographies of narrative reviews. We included cohort, case-control, and cross-sectional studies enrolling at least five adults with primary TBI in whom at least one anterior pituitary axis was assessed at least 12 months following TBI. We excluded studies in which other brain injuries were indistinguishable from TBI. Study quality was assessed using the Newcastle-Ottawa Scale (NOS) score. We also considered studies that determined growth hormone deficiency and adrenocorticotrophic hormone reserve using provocation test to be at low risk of bias. Data were extracted by four independent reviewers and assessed for risk of bias using a data extraction form. We performed meta-analyses using random effect models and assessed heterogeneity using the I² index. We identified 58 publications, of which 29 (2756 participants) were selected for meta-analysis. Twelve of these were deemed to be at low risk of bias and therefore "high-quality," as they had NOS scores greater than 8 and had used provocation tests. The overall prevalence of at least one anterior pituitary hormone dysfunction for all 29 studies was 32% (95% confidence interval [CI] 25-38%). The overall prevalence in the 12 high-quality studies was 34% (95% CI 27-42%). We observed significant heterogeneity that was not solely explained by the risk of bias. Studies with a higher proportion of participants with mild TBI had a lower prevalence of PTPD. Our results show that approximately one-third of TBI sufferers have persistent anterior pituitary dysfunction 12 months or more following trauma. Future research on PTPD should differentiate between mild and moderate/severe TBI.

Clinical picture and the treatment of TBI-induced hypopituitarism

Traumatic brain injury (TBI) is an important public health problem with an increasing incidence in the last years. Relatively few cases are fatal; most individuals will survive and, in the long-term, the sequalae of TBI will include neuroendocrine dysfunctions with a much higher frequency than previously suspected. Patients who develop hypopituitarism after TBI present manifestations due to the number of deficient hormones, severity of hormonal deficiency, and the duration of hypopituitarism without diagnosis and treatment. The clinical spectrum of hypopituitarism is very large and many signs and symptoms of TBI survivors such as fatigue, concentration difficulties, depressive symptoms are nonspecific and overlap with symptoms of post-traumatic stress disorder and variably severe hypopituitarism related to brain damage remaining undiagnosed. This can explain why the diagnosis of hypopituitarism is often missed or delayed after this condition with potentially serious and hazardous consequences for the affected patients. Moreover, clinical experience cumulatively suggests that TBI-associated hypopituitarism is associated with poor recovery and worse outcome, since post-traumatic hypopituitarism is independently associated with cognitive impairment, poor quality of life, abnormal body composition, and adverse metabolic profile. In the present review, the current data related to clinical consequences of pituitary dysfunction after TBI in adult patients and therapeutic approaches are reported.

Chronic Hypopituitarism Associated with Increased Postconcussive Symptoms Is Prevalent after Blast-Induced Mild Traumatic Brain Injury

The most frequent injury sustained by US service members deployed to Iraq or Afghanistan is mild traumatic brain injuries (mTBI), or concussion, by far most often caused by blast waves from improvised explosive devices or other explosive ordnance. TBI from all causes gives rise to chronic neuroendocrine disorders with an estimated prevalence of 25-50%. The current study expands upon our earlier finding that chronic pituitary gland dysfunction occurs with a similarly high frequency after blast-related concussions. We measured circulating hormone levels and accessed demographic and testing data from two groups of male veterans with hazardous duty experience in Iraq or Afghanistan. Veterans in the mTBI group had experienced one or more blast-related concussion. Members of the deployment control (DC) group encountered similar deployment conditions but had no history of blast-related mTBI. 12 of 39 (31%) of the mTBI participants and 3 of 20 (15%) veterans in the DC group screened positive for one or more neuroendocrine disorders. Positive screens for growth hormone deficiency occurred most often. Analysis of responses on self-report questionnaires revealed main effects of both mTBI and hypopituitarism on postconcussive and posttraumatic stress disorder (PTSD) symptoms. Symptoms associated with pituitary dysfunction overlap considerably with those of PTSD. They include cognitive deficiencies, mood and anxiety disorders, sleep problems, diminished quality of life, deleterious changes in metabolism and body composition, and increased cardiovascular mortality. When such symptoms are due to hypopituitarism, they may be alleviated by hormone replacement. These findings suggest consideration of routine post-deployment neuroendocrine screening of service members and veterans who have experienced blast-related mTBI and are reporting postconcussive symptoms.

Post-Traumatic Hypopituitarism-Who Should Be Screened, When, and How?

Traumatic brain injury (TBI) remains a major, global public health concern. Over the last 15 years, a significant body of evidence has emerged demonstrating that post-traumatic hypopituitarism (PTHP) is a common and clinically significant consequence of TBI. Non-specific symptomology and the lack of an agreed approach to screening for PTHP has led to significant under-diagnosis of this debilitating disease. In this review, we will discuss the frequency and clinical significance of acute and chronic PTHP as described in the current literature highlighting the evidence base for screening and hormone replacement in these patients. We will also offer a pragmatic approach to identifying relevant anterior pituitary dysfunction after TBI and a follow-up strategy for those patients. Specific controversies and remaining unanswered questions will be addressed.

MANAGEMENT OF ENDOCRINE DISEASE: Neuroendocrine surveillance and management of neurosurgical patients

Advances in the management of traumatic brain injury, subarachnoid haemorrhage and intracranial tumours have led to improved survival rates and an increased focus on quality of life of survivors. Endocrine sequelae of the acute brain insult and subsequent neurosurgery, peri-operative fluid administration and/or cranial irradiation are now well described. Unrecognised acute hypopituitarism, particularly ACTH/cortisol deficiency and diabetes insipidus, can be life threatening. Although hypopituitarism may be transient, up to 30% of survivors of TBI have chronic hypopituitarism, which can diminish quality of life and hamper rehabilitation. Patients who survive SAH may also develop hypopituitarism, though it is less common than after TBI. The growth hormone axis is most frequently affected. There is also accumulating evidence that survivors of intracranial malignancy, who have required cranial irradiation, may develop hypopituitarism. The time course of the development of hormone deficits is varied, and predictors of pituitary dysfunction are unreliable. Furthermore, diagnosis of GH and ACTH deficiency require dynamic testing that can be resource intensive. Thus the surveillance and management of neuroendocrine dysfunction in neurosurgical patients poses significant logistic challenges to endocrine services. However, diagnosis and management of pituitary dysfunction can be rewarding. Appropriate hormone replacement can improve quality of life, prevent complications such as muscle atrophy, infection and osteoporosis and improve engagement with physiotherapy and rehabilitation.

Voxel-based statistical analysis of brain metabolism in patients with growth hormone deficiency after traumatic brain injury

OBJECTIVE

The aim of this study was to investigate the regional cerebral metabolism related to growth hormone deficiency (GHD) after traumatic brain injury (TBI) using F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET) images.

METHODS

Twenty-three patients with diffuse axonal injury following TBI were enrolled. They underwent brain F-18 FDG PET study and an insulin tolerance test (ITT). According to the results of ITT, they were divided into two groups: patients with GHD and subjects with TBI but normal Growth Hormone (GH). Voxel-based statistical analysis was performed and the regional cerebral glucose metabolism shown on F-18 FDG PET from 10 patients with GHD was compared with those from 13 patients without GHD. Analysis was performed using SPM2 to identify regions where decreased changes in regional cerebral glucose metabolism were significantly related to GHD.

RESULTS

Compared with subjects with TBI but normal GH, patients with GHD after TBI showed decreased cerebral glucose metabolism in the Left superior frontal gyrus, Right angular gyrus, Right superior temporal gyrus, Left inferior temporal gyrus, Left anterior and middle cingulate gyrus and Right anterior and middle cingulate gyrus. (p_uncorrected < 0.005).

CONCLUSIONS

The findings are suggestive of the brain region influenced by GHD. These cortical areas are involved in regulation of intellectual function, executive function and working memory.

GH deficiency after traumatic brain injury: improvement in quality of life with GH therapy: analysis of the KIMS database

OBJECTIVE

Prevalence of GH deficiency (GHD) caused by traumatic brain injury (TBI) is highly variable. Short-term studies show improvement in quality of life (QoL) during GH replacement (GHR), but long-term data are lacking. The aim of this study was to analyse the clinical characteristics of post-traumatic hypopituitarism and the QoL effects of long-term GHR.

DESIGN/METHODS

Pfizer International Metabolic Database patients with GHD caused by TBI and by non-functioning pituitary adenoma (NFPA) were compared regarding: clinical characteristics at baseline and 1-year of GHR, and QoL response up to 8-years of GHR (QoL-AGHDA total scores and dimensions) in relationship with country-specific norms.

RESULTS

TBI patients compared with NFPA patients were younger, diagnosed with GHD 2.4 years later after primary disease onset (P<0.0001), had a higher incidence of isolated GHD, higher GH peak, a more favourable metabolic profile and worse QoL, were shorter by 0.9 cm (1.8 cm when corrected for age and gender; P=0.004) and received higher GH dose (mean difference: 0.04 mg/day P=0.006). In TBI patients, 1-year improvement in QoL was greater than in NFPA (change in QoL-AGHDA score 5.0 vs 3.5, respectively, P=0.04) and was sustained over 8 years. In TBI patients, socialisation normalised after 1 year of GHR, self-confidence and tenseness after 6 years and no normalisation of tiredness and memory was observed.

CONCLUSION

Compared with NFPA, TBI patients presented biochemically with less severe hypopituitarism and worse QoL scores. GHR achieved clinically relevant, long-term benefit in QoL.

Clinical outcomes, predictors, and prevalence of anterior pituitary disorders following traumatic brain injury: a systematic review

OBJECTIVES

To assess the clinical outcomes, predictors, and prevalence of anterior pituitary disorders following traumatic brain injury.

DATA SOURCES

We searched Medline, Embase, Cochrane Registry, BIOSIS, and Trip Database up to February 2012 and consulted bibliographies of narrative reviews and selected articles.

STUDY SELECTION

We included cohort, case-control, cross-sectional studies and randomized trials enrolling at least five adults with blunt traumatic brain injury in whom at least one anterior pituitary axis was assessed. We excluded case series and studies in which other neurological conditions were indistinguishable from traumatic brain injury.

DATA EXTRACTION

Two independent reviewers selected citations, extracted data, and assessed the risk of bias using a standardized form.

DATA SYNTHESIS

We performed meta-analyses using random effect models and assessed heterogeneity using the I index.

RESULTS

We included 66 studies (5,386 patients) evaluating prevalence, 14 evaluating clinical outcomes, and 27 evaluating predictors. Thirty studies were at low risk of bias. Anterior pituitary disorders were associated with a trend toward increased ICU mortality (risk ratio, 1.79; 95% CI, 0.99-3.21; four studies) and no difference in Glasgow Outcome Scale score (mean difference, -0.45; 95% CI, -1.10 to 0.20; three studies). Age (mean difference, 3.19; 95% CI, 0.31-6.08; 19 studies), traumatic brain injury severity (risk ratio, 2.15; 95% CI, 1.20-3.86 for patients with severe vs nonsevere traumatic brain injury; seven studies), and skull fractures (risk ratio, 1.73; 95% CI, 1.03-2.91; six studies) predicted anterior pituitary disorders. Over the long term, 31.6% (95% CI, 23.6-40.1%; 27 studies) of patients had at least one anterior pituitary disorder. We observed significant heterogeneity that was not solely explained by the risk of bias or traumatic brain injury severity.

CONCLUSIONS

Approximately one third of traumatic brain injury patients have persistent anterior pituitary disorder. Older age, traumatic brain injury severity, and skull fractures predict anterior pituitary disorders, which in turn may be associated with higher ICU mortality. Further high-quality studies are warranted to better define the burden of anterior pituitary disorders and to identify high-risk 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.

The negative impact of traumatic brain injury (TBI) on bone in a mouse model

INTRODUCTION

While it is well established that the brain produces hypothalamic hormones and neuropeptides that influence skeletal metabolism, the impact of traumatic brain injury (TBI) on bone is unknown. Based on the recognition from clinical studies that there is an association between TBI and long-term hypothalamic pituitary dysfunction, it was hypothesized that TBI exerts a negative impact on skeletal growth and maintenance.

METHODS

To test the hypothesis, this study employed a repetitive weight drop model for TBI. Four impacts were applied for four consecutive days on 5-week old female C57BL/6 J mice. Bone measurements were taken 2 weeks after the first impact.

RESULTS

Bone mineral content (BMC), bone area (B area) and bone mineral density (BMD) in the total body were reduced by 14.5%, 9.8% and 5.2%, respectively, in the impacted vs. control mice. There was a 17.1% reduction in total volumetric BMD (vBMD) and a 4.0% reduction in material vBMD in cortical bone. In trabecular bone, there was a 44.0% reduction in BV/TV. Although there was no change in the cross-sectional bone size, the tibial growth plate and the tibia itself were shortened.

CONCLUSION

The repetitive animal TBI model produced an immediate, strong negative impact on bone mass acquisition in young mice.

The effects of repeat traumatic brain injury on the pituitary in adolescent rats

Adolescents are one of the highest groups at risk for sustaining both traumatic brain injury (TBI) and repeat TBI (RTBI). Consequences of endocrine dysfunction following TBI have been routinely explored in adults, but studies in adolescents are limited, and show an incidence rate of endocrine dysfunction in 16-61% in patients, 1-5 years after injury. Similar to in adults, the most commonly affected axis is growth hormone (GH) and insulin-like growth hormone 1 (IGF-1). Despite TBI being the primary cause of morbidity and mortality among the pediatric population, there are currently no experimental studies specifically addressing the occurrence of pituitary dysfunction in adolescents. The present study investigated whether a sham, single injury or four repeat injuries (24 h interval) delivered to adolescent rats resulted in disruption of the GH/IGF-1 axis. Circulating levels of basal GH and IGF-1 were measured at baseline, 24 h, 72 h, 1 week, and 1 month after injury, and vascular permeability of the pituitary gland was quantified via Evans Blue dye extravasation. Changes in weight and length of animals were measured as a potential consequence of GH and IGF-1 disruption. The results from the current study demonstrate that RTBI results in significant acute and chronic decreases in circulation of GH and IGF-1, reduction in weight gain and growth, and an increase in Evans Blue dye extravasation in the pituitary compared with sham and single injury animals. RTBI causes significant disruption of the GH/IGF-1 axis that may ultimately affect normal cognitive and physical development during adolescence.

The impact of traumatic brain injury on pituitary function

It is paramount that clinicians who care for patients with traumatic brain injury (TBI) at any point in time, including neurosurgeons, rehabilitation physicians, internists, neurologists, and endocrinologists, are aware of the prevalence of posttraumatic hypopituitarism and its impacts on acute and long-term recovery. This article reviews the natural history, pathophysiology, and presenting features of hypopituitarism occurring after TBI. Proposed methodologies for screening, diagnosis, and initiation of treatment are discussed, as well as the effect of hormone replacement therapy on clinical outcomes.

Pituitary function and functional outcome in adults after severe traumatic brain injury: the long-term perspective

Post-traumatic hypopituitarism (PTHP) has been linked to disability and decreased quality of life. However, no studies have addressed the long-term consequences of PTHP in adults with severe traumatic brain injury (TBI) only. In this study, we evaluated the relationship between pituitary function, quality of life, and functioning in 51 patients (16-65 years of age) with severe TBI who were admitted to Sahlgrenska University Hospital, Gothenburg from 1999 to 2002. The patients were assessed once, 2-10 years after trauma. Data from the time of injury were collected retrospectively to adjust for injury severity. Outcome measures included hormonal testing, the Short Form-36 Health Survey, the Glasgow outcome scale-extended, and a self-report questionnaire specifically designed for this study and based on the International Classification of Functioning, Disability and Health. Of 51 patients, 14 (27.5%) presented with PTHP, and 11 (21.6%) had isolated growth hormone deficiency. Patients with PTHP were more often overweight at follow-up (p=0.01); the higher body mass index was partially explained by PTHP (R2 change=0.07, p=0.001). Otherwise no significant correlation was found among PTHP, functioning, or patient-reported quality of life. This study-which is unique in the homogeneity of the patients, the long follow-up time, and the use of injury severity as an outcome predictor-did not confirm results from previous studies linking PTHP to a worse outcome. Therefore, screening for PTHP might be restricted to specific subgroups such as overweight patients, indicating growth hormone deficiency.

Neuroendocrine consequences of traumatic brain injury

PURPOSE OF REVIEW

This article attempts to summarize findings of recent publications addressing the prevalence, effects, and treatment of pituitary hormone deficiency following traumatic brain injury (TBI).

RECENT FINDINGS

A number of recent studies of TBI victims offer larger samples and much longer follow-up times. However, the prevalence of pituitary hormone deficiency continues to vary widely, underscoring the influence of patient selection, differences in endocrine testing, and patient's comorbidities and age. Growth hormone deficiency (GHD) continues to be the most frequently detected type of pituitary dysfunction. Several reports show the influence of GHD on functional outcomes of TBI victims beyond what is predicted by trauma severity. Emerging data support the notion growth hormone (GH) replacement as a useful intervention to improve symptomatology and functional outcomes among adequately selected GH-deficient patients recovering from TBI.

SUMMARY

Pituitary dysfunction is prevalent following TBI. Pituitary dysfunction seems to influence functional outcomes in some patients recovering from brain injury. Adequately selected patients could benefit from hormonal replacement.

Sports-related chronic repetitive head trauma as a cause of pituitary dysfunction

Traumatic brain injury (TBI) is recognized as a cause of hypopituitarism even after mild TBI. Although over the past decade, a growing body of research has detailed neuroendocrine changes induced by TBI, the mechanisms and risk factors responsible for this pituitary dysfunction are still unclear. Around the world, sports-especially combative sports-are very popular. However, sports are not generally considered as a cause of TBI in most epidemiological studies, and the link between sports-related head trauma and hypopituitarism has not been investigated until recently. Thus, there is a paucity of data regarding this important concern. Because of the large number of young sports participants with near-normal life expectancy, the implications of undiagnosed or untreated postconcussion pituitary dysfunction can be dramatic. Understanding the pathophysiological mechanisms and risk factors of hypopituitarism caused by sports injuries is thus an important issue that concerns both medical staff and sponsors of sports. The aim of this paper was to summarize the best evidence for understanding the pathophysiological mechanisms and to discuss the current data and recommendations on sports-related head trauma as a cause of hypopituitarism.

Lasting pituitary hormone deficiency after traumatic brain injury

Pituitary deficiencies have been reported after traumatic brain injury (TBI) and may contribute to lasting cognitive disorders in this context. In a population of TBI patients with persistent cognitive and/or behavioral disorders, we sought to determine the prevalence of lasting pituitary deficiency and relationships with TBI severity, cognitive disorders, and impairments in activities of daily living (ADL). Fifty-five patients were included (mean age 36.1 years; 46 men) at least 1 year after TBI. They underwent a comprehensive evaluation of pituitary function (basic tests and stimulation), initial TBI severity, and long-term outcomes (cognitive performance, Glasgow Outcome Scale score, impact on ADL, and quality of life [QoL]). We used chi-squared and Mann-Whitney tests to probe for significant (p≤0.05) relationships between pituitary disorders and other parameters. Thirty-eight (69%) patients had at least one pituitary hormone deficiency. Growth hormone deficiency was more prevalent (severe: 40.0%; partial: 23.6%) than corticotropin (27.3%) or thyrotropin (21.8%) deficiencies. Other deficiencies were rare. Growth hormone deficiency was associated with attention and verbal memory disorders and reduced involvement in ADL. We did not find any relationship between pituitary deficiency and the TBI's initial severity. In a multivariate analysis, the TBI severity was introduced as a first factor, and pituitary deficits as a secondary factor for explaining the late outcome (ADL and QoL). In conclusion, TBI patients with cognitive sequelae must undergo pituitary screening because growth hormone, corticotropin, and thyrotropin deficits are particularly common and can adversely affect ADL and reduce QoL.

High prevalence of chronic pituitary and target-organ hormone abnormalities after blast-related mild traumatic brain injury

Studies of traumatic brain injury from all causes have found evidence of chronic hypopituitarism, defined by deficient production of one or more pituitary hormones at least 1 year after injury, in 25–50% of cases. Most studies found the occurrence of posttraumatic hypopituitarism (PTHP) to be unrelated to injury severity. Growth hormone deficiency (GHD) and hypogonadism were reported most frequently. Hypopituitarism, and in particular adult GHD, is associated with symptoms that resemble those of PTSD, including fatigue, anxiety, depression, irritability, insomnia, sexual dysfunction, cognitive deficiencies, and decreased quality of life. However, the prevalence of PTHP after blast-related mild TBI (mTBI), an extremely common injury in modern military operations, has not been characterized. We measured concentrations of 12 pituitary and target-organ hormones in two groups of male US Veterans of combat in Iraq or Afghanistan. One group consisted of participants with blast-related mTBI whose last blast exposure was at least 1 year prior to the study. The other consisted of Veterans with similar military deployment histories but without blast exposure. Eleven of 26, or 42% of participants with blast concussions were found to have abnormal hormone levels in one or more pituitary axes, a prevalence similar to that found in other forms of TBI. Five members of the mTBI group were found with markedly low age-adjusted insulin-like growth factor-I (IGF-I) levels indicative of probable GHD, and three had testosterone and gonadotropin concentrations consistent with hypogonadism. If symptoms characteristic of both PTHP and PTSD can be linked to pituitary dysfunction, they may be amenable to treatment with hormone replacement. Routine screening for chronic hypopituitarism after blast concussion shows promise for appropriately directing diagnostic and therapeutic decisions that otherwise may remain unconsidered and for markedly facilitating recovery and rehabilitation.