Which patient requires neuroendocrine assessment following traumatic brain injury, when and how?

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.

Endocrine Dysfunction After Traumatic Brain Injury: An Ignored Clinical Syndrome?

Traumatic brain injury (TBI) incurs substantial health and economic burden, as it is the leading reason for death and disability globally. Endocrine abnormalities are no longer considered a rare complication of TBI. The reported prevalence is variable across studies, depending on the time frame of injury, time and type of testing, and variability in hormonal values considered normal across different studies. The present review reports evidence on the endocrine dysfunction that can occur after TBI. Several aspects, including the pathophysiological mechanisms, clinical consequences/challenges (in the acute and chronic phases), screening and diagnostic workup, principles of therapeutic management, and insights on future directions/research agenda, are presented. The management of hypopituitarism following TBI involves hormonal replacement therapy. It is essential for health care providers to be aware of this complication because at times, symptoms may be subtle and may be mistaken to be caused by brain injury itself. There is a need for stronger evidence for establishing recommendations for optimum management so that they can be incorporated as standard of care in TBI management.

Screening for possible hypopituitarism following mild traumatic brain injury: The first all-female study. Who do we need to evaluate further?

BACKGROUND

Studies on hypopituitarism (HP) following mild traumatic brain injury (mTBI) have focused on male populations although women may be more susceptible to the sequelae of mTBI. This is, to the best of our knowledge, the first all-female study screening for HP following mTBI.

OBJECTIVE

Screening for possible HP in female athletes reporting a history of one or more mTBI.

METHODS

Pituitary hormone screening blood tests (SBT) were performed in 133 of the 151 female athletes included. Repeated results outside the reference value (O-RV) were considered abnormal necessitating further endocrinological evaluation.

RESULTS

Repeated SBT were O-RV in 88 women (66.2%). Decreased levels of serum insulin growth factor 1 (S-IGF1) were found in 55.6% of participants and elevated levels of serum prolactin (S-prolactin) in 22.6%. Serum cortisol levels were below the RV in 6.0% and thyroid hormonal levels in 11.3%. Lower age and increased number of mTBI symptoms correlated significantly with the risk of hormonal results O-RV.

CONCLUSION

The majority of the study population had SBT O-RV, warranting further workup of possible HP. Decreased levels of S-IGF1 were most commonly observed followed by elevated S-prolactin possibly indicating hypothalamic-pituitary impairment. Lower age and increased number of symptoms of mTBI may indicate the need to screen for HP.

Hypopituitary syndrome with pituitary crisis in a patient with traumatic shock: A case report

BACKGROUND

Shock is among the most common conditions that clinicians face in intensive care unit (ICU), of which hypovolemic shock is encountered most frequently; some patients instead suffer from neurogenic, cardiogenic, or infectious forms of shock. However, there are additional types of shock from unusual causes that are often undiagnosed. Here, we report the case of a patient who was initially misdiagnosed with hypovolemic shock, but exhibited persistent hypotension because of continuous fluid replacement and vasoactive drug administration, and was eventually diagnosed with hypopituitarism with crisis.

CASE SUMMARY

A 73-year-old Chinese man was admitted to the neurosurgery department following injury caused by a heavy object with symptoms of anemia and high fever. He was transferred to the ICU on the fourth day after hospitalization because of hypotension and unconsciousness. Blood analysis indicated that the patient was suffering from anemia and thrombocytopenia. Ultrasonography showed that there was no apparent abnormality in the cardiac structure but there was mild tricuspid regurgitation. Computed tomography revealed that there were signs of hemorrhage at the right basal ganglia; accordingly, hypovolemic shock, possibly septic shock, was initially considered. Even after routine treatment for shock, the hypotension remained severe. The patient was again thoroughly examined to investigate the underlying cause. The antishock therapy was supplemented with corticosteroids to counter potential hypopituitarism. The patient made a full recovery, and the blood pressure returned to normal.

CONCLUSION

A case of pituitary adenoma with multiple injuries was identified. Because of hypopituitarism, functionality of the corresponding endocrine system was restricted, with the most pronounced manifestation being unstable blood circulation requiring hormone replacement therapy. Such cases are relatively rare but may occur if multiple injuries are sustained. The present case represents a reference for the clinical treatment of patients with multiple injuries.

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.

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.

Growth Hormone Deficiency Following Traumatic Brain Injury

Traumatic brain injury (TBI) is fairly common and annually affects millions of people worldwide. Post traumatic hypopituitarism (PTHP) has been increasingly recognized as an important and prevalent clinical entity. Growth hormone deficiency (GHD) is the most common pituitary hormone deficit in long-term survivors of TBI. The pathophysiology of GHD post TBI is thought to be multifactorial including primary and secondary mechanisms. An interplay of ischemia, cytotoxicity, and inflammation post TBI have been suggested, resulting in pituitary hormone deficits. Signs and symptoms of GHD can overlap with those of TBI and may delay rehabilitation/recovery if not recognized and treated. Screening for GHD is recommended in the chronic phase, at least six months to a year after TBI as GH may recover in those with GHD in the acute phase; conversely, it may manifest in those with a previously intact GH axis. Dynamic testing is the standard method to diagnose GHD in this population. GHD is associated with long-term poor medical outcomes. Treatment with recombinant human growth hormone (rhGH) seems to ameliorate some of these features. This review will discuss the frequency and pathophysiology of GHD post TBI, its clinical consequences, and the outcomes of treatment with GH replacement.

The frequency and the diagnosis of pituitary dysfunction after traumatic brain injury

PURPOSE

Clinical research studies over the last 15 years have reported a significant burden of hypopituitarism in survivors of traumatic brain injury (TBI). However, debate still exists about the true prevalence of hypopituitarism after head injury.

METHODS

We have reviewed the literature describing the frequency of post-traumatic hypopituitarism and discuss the factors which may explain the variable frequency of the reported deficits in clinical studies including research methodology and the natural history of the disease.

RESULTS

Pituitary hormone perturbations in the acute phase following injury are frequent but are difficult to attribute to traumatic pituitary damage due to physiological hormonal changes in acute illness, the confounding effect of medications, other co-morbidities and lack of appropriate control subjects. Nevertheless, a small number of studies have emphasised the clinical importance of acute, dynamic disturbance of the hypothalamic-pituitary-adrenal axis. There is a much larger evidence base examining the frequency of hypopituitarism in the chronic, recovery phase following head injury. These studies report a very broad prevalence of long-term pituitary hormone dysfunction in survivors of TBI. However, systematic review suggests the prevalence to be between 27 and 31%.

CONCLUSION

Survivors of head injury are at risk of pituitary hormone dysfunction and we suggest an approach to the diagnosis of post-traumatic hypopituitarism in routine clinical practice.

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.

A neurosurgical approach to traumatic brain injury and post-traumatic hypopituitarism

PURPOSE

Traumatic brain injury (TBI) is a common cause of mortality and major disability worldwide. The initial management often depends on the severity of the injury. Pituitary dysfunction can develop as a sequela of TBI, and can have long-term, debilitating impact on the patients. Early identification and prompt intervention of post-traumatic hypopituitarism (PTHP) is essential to prevent or minimize the adverse consequences of this condition. We hereby provide an overview of the current management of TBI from a neurosurgical standpoint. We then review the pathophysiology and risk factors of developing PTHP, as well as our recommendations for its management.

METHODS

A review of current literature on TBI and PTHP, including primary research articles, reviews and clinical guidelines.

RESULTS

The current neurosurgical approach to the management of TBI is presented, followed by the pathophysiology and risk factors of PTHP, as well as our recommendations for its management.

CONCLUSIONS

Post-traumatic hypopitutiarism is a serious and potentially debilitating condition that is likely under-recognised and under-diagnosed. From a neurosurgical perspective, we advocate a pragmatic approach, i.e. screening those considered at high risk of developing PTHP based on clinical features and biochemical/endocrinological testings; and referring them to a specialist endocrinologist for further management as indicated.

The role of autoimmunity in pituitary dysfunction due to traumatic brain injury

PURPOSE

Traumatic brain injury (TBI) is one of the most common causes of mortality and long-term disability and it is associated with an increased prevalence of neuroendocrine dysfunctions. Post-traumatic hypopituitarism (PTHP) results in major physical, psychological and social consequences leading to impaired quality of life. PTHP can occur at any time after traumatic event, evolving through various ways and degrees of deficit, requiring appropriate screening for early detection and treatment. Although the PTHP pathophysiology remains to be elucitated, on the basis of proposed hypotheses it seems to be the result of combined pathological processes, with a possible role played by hypothalamic-pituitary autoimmunity (HPA). This review is aimed at focusing on this possible role in the development of PTHP and its potential clinical consequences, on the basis of the data so far appeared in the literature and of some results of personal studies on this issue.

METHODS

Scrutinizing the data so far appeared in literature on this topic, we have found only few studies evaluating the autoimmune pattern in affected patients, searching in particular for antipituitary and antihypothalamus autoantibodies (APA and AHA, respectively) by simple indirect immunofluorescence.

RESULTS

The presence of APA and/or AHA at high titers was associated with an increased risk of onset/persistence of PTHP.

CONCLUSIONS

HPA seems to contribute to TBI-induced pituitary damage and related PTHP. However, further prospective studies in a larger cohort of patients are needed to define etiopathogenic and diagnostic role of APA/AHA in development of post-traumatic hypothalamic/pituitary dysfunctions after a TBI.

The screening and management of pituitary dysfunction following traumatic brain injury in adults: British Neurotrauma Group guidance

Pituitary dysfunction is a recognised, but potentially underdiagnosed complication of traumatic brain injury (TBI). Post-traumatic hypopituitarism (PTHP) can have major consequences for patients physically, psychologically, emotionally and socially, leading to reduced quality of life, depression and poor rehabilitation outcome. However, studies on the incidence of PTHP have yielded highly variable findings. The risk factors and pathophysiology of this condition are also not yet fully understood. There is currently no national consensus for the screening and detection of PTHP in patients with TBI, with practice likely varying significantly between centres. In view of this, a guidance development group consisting of expert clinicians involved in the care of patients with TBI, including neurosurgeons, neurologists, neurointensivists and endocrinologists, was convened to formulate national guidance with the aim of facilitating consistency and uniformity in the care of patients with TBI, and ensuring timely detection or exclusion of PTHP where appropriate. This article summarises the current literature on PTHP, and sets out guidance for the screening and management of pituitary dysfunction in adult patients with TBI. It is hoped that future research will lead to more definitive recommendations in the form of guidelines.

Can early clinical parameters predict post-traumatic pituitary dysfunction in severe traumatic brain injury?

BACKGROUND

Post-traumatic hypopituitarism is a major complication after severe head trauma. The aim of our study was to evaluate the possible role of early clinical parameters in the development of endocrine deficits.

METHODS

Data on endocrine function, on-admission clinical-, laboratory-, and ICU-monitored parameters were available in 63 patients of the surviving 86 severe head injury patients (post-resuscitation GCS under 8) treated at one neurosurgical center during a 10-year period.

RESULTS

Hypopituitarism was diagnosed in 68.3 % of the patients. The most frequently affected pituitary axis was the growth hormone (GH): GH deficiency or insufficiency was present in 50.8 %. Central hypogonadism affected 23.8 % of male patients; hypothyroidism and secondary adrenal failure were found in 22.2 and 9.5 % of the investigated population, respectively. Early onset (within 1 year of brain injury) hypopituitarism was found in 24 patients. No connection was found between the development of hypopituitarism and any of the clinical parameters assessed on-admission or at ICU. Significant correlations were found between early endocrine dysfunctions and surgical intervention (OR: 4.64) and the diagnosis of subdural hematoma (OR: 12). In our population, after road traffic accidents, the development of late-onset hypopituitarism was less prevalent (OR: 0.22).

CONCLUSIONS

Since our results do not indicate any reliable predictive parameter for the development of endocrine dysfunction in a cohort of patients with severe traumatic brain injury, regular endocrine screening of this specific patient population seems obligatory.

Diffuse traumatic brain injury affects chronic corticosterone function in the rat

As many as 20-55% of patients with a history of traumatic brain injury (TBI) experience chronic endocrine dysfunction, leading to impaired quality of life, impaired rehabilitation efforts and lowered life expectancy. Endocrine dysfunction after TBI is thought to result from acceleration-deceleration forces to the brain within the skull, creating enduring hypothalamic and pituitary neuropathology, and subsequent hypothalamic-pituitary endocrine (HPE) dysfunction. These experiments were designed to test the hypothesis that a single diffuse TBI results in chronic dysfunction of corticosterone (CORT), a glucocorticoid released in response to stress and testosterone. We used a rodent model of diffuse TBI induced by midline fluid percussion injury (mFPI). At 2months postinjury compared with uninjured control animals, circulating levels of CORT were evaluated at rest, under restraint stress and in response to dexamethasone, a synthetic glucocorticoid commonly used to test HPE axis regulation. Testosterone was evaluated at rest. Further, we assessed changes in injury-induced neuron morphology (Golgi stain), neuropathology (silver stain) and activated astrocytes (GFAP) in the paraventricular nucleus (PVN) of the hypothalamus. Resting plasma CORT levels were decreased at 2months postinjury and there was a blunted CORT increase in response to restraint induced stress. No changes in testosterone were measured. These changes in CORT were observed concomitantly with altered complexity of neuron processes in the PVN over time, devoid of neuropathology or astrocytosis. Results provide evidence that a single moderate diffuse TBI leads to changes in CORT function, which can contribute to the persistence of symptoms related to endocrine dysfunction. Future experiments aim to evaluate additional HP-related hormones and endocrine circuit pathology following diffuse TBI.

Neuroendocrine Disturbances One to Five or More Years after Traumatic Brain Injury and Aneurysmal Subarachnoid Hemorrhage: Data from the German Database on Hypopituitarism

Neuroendocrine disturbances are common after traumatic brain injury (TBI) and aneurysmal subarachnoid hemorrhage (SAH), but only a few data exist on long-term anterior pituitary deficiencies after brain injury. We present data from the Structured Data Assessment of Hypopituitarism after TBI and SAH, a multi-center study including 1242 patients. We studied a subgroup of 351 patients, who had sustained a TBI (245) or SAH (106) at least 1 year before endocrine assessment (range 1-55 years) in a separate analysis. The highest prevalence of neuroendocrine disorders was observed 1-2 years post-injury, and it decreased over time only to show another maximum in the long-term phase in patients with brain injury occurring ≥5 years prior to assessment. Gonadotropic and somatotropic insufficiencies were most common. In the subgroup from 1 to 2 years after brain injury (n = 126), gonadotropic insufficiency was the most common hormonal disturbance (19%, 12/63 men) followed by somatotropic insufficiency (11.5%, 7/61), corticotropic insufficiency (9.2%, 11/119), and thyrotropic insufficiency (3.3%, 4/122). In patients observed ≥ 5 years after brain injury, the prevalence of somatotropic insufficiency increased over time to 24.1%, whereas corticotropic and thyrotrophic insufficiency became less frequent (2.5% and 0%, respectively). The prevalence differed regarding the diagnostic criteria (laboratory values vs. physician`s diagnosis vs. stimulation tests). Our data showed that neuroendocrine disturbances are frequent even years after TBI or SAH, in a cohort of patients who are still on medical treatment.

Circulating MicroRNAs as Potential Biomarkers for Traumatic Brain Injury-Induced Hypopituitarism

Traumatic brain injury (TBI), a worldwide public health problem, has recently been recognized as a common cause of pituitary dysfunction. Circulating microRNAs (miRNAs) present in the sera are characteristically altered in many pathological conditions and have been used as diagnostic markers for specific diseases. It is with this goal that we planned to study miRNA expression in patients with TBI-induced hypopituitarism. Thirty-eight patients (27 male, 11 female; mean age, 43 ± 18 years) who had been admitted to the neurosurgery intensive care unit due to TBI were included in the acute phase of the study. In the chronic phase, miRNA expression profile blood samples were drawn from 25 patients who had suffered TBI 5 years ago. In the acute phase (on Days 1, 7, and 28), a substantial amount of patients (26%, 40%, and 53%; respectively) had hypopituitarism (acute adrenocorticotropic hormone deficiency). In the chronic phase eight of 25 patients (32%) had TBI-induced-hypopituitarism. Forty-seven age-gender-similar healthy controls (25 male, 22 female, mean age: 41 ± 14 years) were included in the study. In order to identify potential candidate miRNA/miRNAs whose levels had been altered in response to TBI-induced hypopituitarism, 740 miRNA expression analyses were performed in the sera of TBI patients by high throughput real-time polymerase chain reaction. Statistical analyses showed that miRNA-126-3p (miR-126-3p) and miRNA-3610 (miR-3610) were detected in the sera of patients who developed hypopituitarism on the 1st, 7th, and 28th days, and in the 5th year following TBI. In addition, miRNA-3907 showed statistically significant and constant dynamic changes on the 1st, 7th, and 28th days, and in the 5th year in the patients with TBI. Our results indicated that altered expression of miR-126-3p and miR-3610 may play an important role in the development of TBI-induced hypopituitarism.

Pituitary and/or hypothalamic dysfunction following moderate to severe traumatic brain injury: Current perspectives

There is an increasing deliberation regarding hypopituitarism following traumatic brain injury (TBI) and recent data have suggested that pituitary dysfunction is very common among survivors of patients having moderate-severe TBI which may evolve or resolve over time. Due to high prevalence of pituitary dysfunction after moderate-severe TBI and its association with increased morbidity and poor recovery and the fact that it can be easily treated with hormone replacement, it has been suggested that early detection and treatment is necessary to prevent long-term neurological consequences. The cause of pituitary dysfunction after TBI is still not well understood, but evidence suggests few possible primary and secondary causes. Results of recent studies focusing on the incidence of hypopituitarism in the acute and chronic phases after TBI are varied in terms of severity and time of occurrence. Although the literature available does not show consistent values and there is difference in study parameters and diagnostic tests used, it is clear that pituitary dysfunction is very common after moderate to severe TBI and patients should be carefully monitored. The exact timing of development cannot be predicted but has suggested regular assessment of pituitary function up to 1 year after TBI. In this narrative review, we aim to explore the current evidence available regarding the incidence of pituitary dysfunction in acute and chronic phase post-TBI and recommendations for screening and follow-up in these patients. We will also focus light over areas in this field worthy of further investigation.

Pituitary dysfunction after traumatic brain injury: a clinical and pathophysiological approach

Traumatic brain injury (TBI) is a growing public health problem worldwide and is a leading cause of death and disability. The causes of TBI include motor vehicle accidents, which are the most common cause, falls, acts of violence, sports-related head traumas, and war accidents including blast-related brain injuries. Recently, pituitary dysfunction has also been described in boxers and kickboxers. Neuroendocrine dysfunction due to TBI was described for the first time in 1918. Only case reports and small case series were reported until 2000, but since then pituitary function in TBI victims has been investigated in more detail. The frequency of hypopituitarism after TBI varies widely among different studies (15-50% of the patients with TBI in most studies). The estimates of persistent hypopituitarism decrease to 12% if repeated testing is applied. GH is the most common hormone lost after TBI, followed by ACTH, gonadotropins (FSH and LH), and TSH. The underlying mechanisms responsible for pituitary dysfunction after TBI are not entirely clear; however, recent studies have shown that genetic predisposition and autoimmunity may have a role. Hypopituitarism after TBI may have a negative impact on the pace or degree of functional recovery and cognition. What is not clear is whether treatment of hypopituitarism has a beneficial effect on specific function. In this review, the current data related to anterior pituitary dysfunction after TBI in adult patients are updated, and guidelines for the diagnosis, follow-up strategies, and therapeutic approaches are reported.

Neuroendocrine Disturbances after Brain Damage: An Important and Often Undiagnosed Disorder

Traumatic brain injury (TBI) is a common and significant public health problem all over the world. Until recently, TBI has been recognized as an uncommon cause of hypopituitarism. The studies conducted during the last 15 years revealed that TBI is a serious cause of hypopituitarism. Although the underlying pathophysiology has not yet been fully clarified, new data indicate that genetic predisposition, autoimmunity and neuroinflammatory changes may play a role in the development of hypopituitarism. Combative sports, including boxing and kickboxing, both of which are characterized by chronic repetitive head trauma, have been shown as new causes of neuroendocrine abnormalities, mainly hypopituitarism, for the first time during the last 10 years. Most patients with TBI-induced pituitary dysfunction remain undiagnosed and untreated because of the non-specific and subtle clinical manifestations of hypopituitarism. Replacement of the deficient hormones, of which GH is the commonest hormone lost, may not only reverse the clinical manifestations and neurocognitive dysfunction, but may also help posttraumatic disabled patients resistant to classical treatment who have undiagnosed hypopituitarism and GH deficiency in particular. Therefore, early diagnosis, which depends on the awareness of TBI as a cause of neuroendocrine abnormalities among the medical community, is crucially important.

Hypopituitarism after traumatic brain injury

The prevalence of hypopituitarism after traumatic brain (TBI) injury is widely variable in the literature; a meta-analysis determined a pooled prevalence of anterior hypopituitarism of 27.5%. Growth hormone deficiency is the most prevalent hormone insufficiency after TBI; however, the prevalence of each type of pituitary deficiency is influenced by the assays used for diagnosis, severity of head trauma, and time of evaluation. Recent studies have demonstrated improvement in cognitive function and cognitive quality of life with substitution therapy in GH-deficient patients after TBI.

Pituitary dysfunction following traumatic brain injury: clinical perspectives

Traumatic brain injury (TBI) is a well recognized public health problem worldwide. TBI has previously been considered as a rare cause of hypopituitarism, but an increased prevalence of neuroendocrine dysfunction in patients with TBI has been reported during the last 15 years in most of the retrospective and prospective studies. Based on data in the current literature, approximately 15%-20% of TBI patients develop chronic hypopituitarism, which clearly suggests that TBI-induced hypopituitarism is frequent in contrast with previous assumptions. This review summarizes the current data on TBI-induced hypopituitarism and briefly discusses some clinical perspectives on post-traumatic anterior pituitary hormone deficiency.

Treatment of endocrine disorders in the neuroscience intensive care unit

OPINION STATEMENT

This review discusses concepts and treatments associated with the most clinically relevant areas of acute endocrine dysfunction amongst patients with common diseases in neuroscience intensive care units (Neuro ICUs). We highlight the following points:• While a thorough work-up for hyponatremia when it is present is always warranted, subarachnoid hemorrhage (SAH) patients who are in a time window concerning for cerebral vasospasm and who are hyponatremic with high urine output are generally thought to have cerebral salt wasting. These patients are typically treated with a combination of continuous hypertonic saline infusion and fludrocortisone.• Diabetes insipidus (DI) is often seen in patients fulfilling death by neurological criteria, as well as in patients with recent pituitary surgery and less often in SAH and traumatic brain injury patients who are not brain dead. Patients with DI in the Neuro ICU often cannot drink to thirst and may require a combination of desmopression/vasopressin administration, aggressive fluid repletion, and serum sodium monitoring.• Diagnosing adrenal insufficiency immediately following pituitary injury is complicated by the fact that the expected atrophy of the adrenal glands, due to lack of a stimulus from pituitary adrenocorticotropic hormone, may take up to 6 weeks to develop. Cosyntropin testing can be falsely normal during this period.• Both hyperglycemia (glucose >200 mg/dL) and hypoglycemia (glucose <50 mg/dL) are strongly associated with neurological morbidity and mortality in ICUs and should be avoided. Glucose concentrations between 120-160 mg/dL can serve as a reasonable target for insulin infusion protocols.• There is no data to suggest that treatment of abnormal thyroid function tests in nonthyroidal illness syndrome/sick euthyroid leads to benefits in either mortality or morbidity. True myxedema coma is a rare clinical diagnosis that is treated with intravenous levothyroxine accompanied by stress-dose steroids.

Screening for hypopituitarism in 509 patients with traumatic brain injury or subarachnoid hemorrhage

We performed a screening on patients with traumatic brain injury (TBI) or subarachnoid hemorrhage (SAH) to determine the prevalence of post-traumatic hypopituitarism in neurorehabilitation in a cross-sectional, observational single-center study. In addition, the therapeutic consequences of our screening were analyzed retrospectively. From February 2006 to August 2009, patients between 18 and 65 years (n=509) with the diagnosis of TBI (n=340) or SAH (n=169) were screened within two weeks of admittance to neurorehabilitation as clinical routine. Blood was drawn to determine fasting cortisol, free thyroxine (fT4), prolactin, testosterone or estradiol, and insulin-like growth factor I (IGF-I). Patients with abnormalities in the screening or clinical signs of hypopituitarism received further stimulation tests: growth hormone releasing hormone -L-arginine-test and adrenocorticotrophic hormone (ACTH)-test (n=36); ACTH-test alone (n=26); or insulin tolerance test (n=56). In our screening of 509 patients, 28.5% showed lowered values in at least one hormone of the hypothalamus-pituitary axis and 4.5% in two or more axes. The most common disturbance was a decrease of testosterone in 40.7% of all men (in the following 13/131 men were given substitution therapy). Low fT4 was detected in 5.9% (n=3 were given substitution therapy). Low IGF-I was detected in 5.8%, low cortisol in 1.4%, and low prolactin in 0.2%; none were given substitution therapy. Further stimulation tests revealed growth hormone deficiency in 20.7% (n=19/92) and hypocortisolism in 23.7% (n=28/118). Laboratory values possibly indicating hypopituitarism (33%) were common but did not always implicate post-traumatic hypopituitarism. Laboratory values possibly indicating hypopituitarism were common in our screening but most patients were clinically not diagnosed as pituitary insufficient and did not receive hormone replacement therapy. A routine screening of all patients in neurorehabilitation without considering the time since injury, the severity of illness and therapeutic consequences seems not useful.

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.

Diabetes insipidus contributes to traumatic brain injury pathology via CD36 neuroinflammation

Each year, over one million people in the United States are affected by traumatic brain injury (TBI). Symptoms of both acute and chronic neuroinflammation follow TBI, coinciding with a robust immune response and activation of the brain's endogenous repair mechanisms. TBI can lead to endocrine failure as a result of damage to the thalamic region of the brain, evidenced by excessive thirst and polyuria often accompanying TBI. These symptoms indicate the presence of diabetes insipidus (DI), a disruption of water homeostasis due to antidiuretic hormone deficiency. This deficiency accompanies a mechanical or neuroinflammatory damage to the thalamic region during TBI, evidenced by increased expression of inflammatory microglial marker MHCII in this brain region. Excessive thirst and urinations, which are typical DI symptoms, in our chronic TBI rats also suggest a close connection between TBI and DI. We seek to bridge this gap between TBI and DI through investigation of the Cluster of Differentiation 36 (CD36) receptor. This receptor is associated with Low-Density Lipoprotein (LDL) deregulation, pro-inflammatory events, and innate immunity regulation. We posit that CD36 exacerbates TBI through immune activation and subsequent neuroinflammation. Indeed, scientific evidence already supports pathological interaction of CD36 in other neurological disorders including stroke and Alzheimer's disease. We propose that DI contributes to TBI pathology via CD36 neuroinflammation. Use of CD36 as a biomarker may provide insights into treatment and disease pathology of TBI and DI. This unexplored avenue of research holds potential for a better understanding and treatment of TBI and DI.

Approach to testing growth hormone (GH) secretion in obese subjects

Identification of adults with GH deficiency (GHD) is challenging because clinical features of adult GHD are not distinctive and because clinical suspicion must be confirmed by biochemical tests. Adults are selected for testing for adult GHD if they have a high pretest probability of GHD, ie, if they have hypothalamic-pituitary disease, if they have received cranial irradiation or central nervous system tumor treatment, or if they survived traumatic brain injury or subarachnoid hemorrhage. Testing should only be carried out if a decision has already been made that if deficiency is found it will be treated. There are many pharmacological GH stimulation tests for the diagnosis of GHD; however, none fulfill the requirements for an ideal test having high discriminatory power; being reproducible, safe, convenient, and economical; and not being dependent on confounding factors such as age, gender, nutritional status, and in particular obesity. In obesity, GH secretion is reduced, GH clearance is enhanced, and stimulated GH secretion is reduced, causing a false-positive result. This functional hyposomatotropism in obesity is fully reversed by weight loss. In conclusion, GH stimulation tests should be avoided in obese subjects with very low pretest probability.