Provocative hypothalamopituitary axis tests in severe head injury: correlations with severity and prognosis

Pituitary dysfunction after traumatic brain injury: prevalence and screening strategies

INTRODUCTION

Pituitary gland is vulnerable to traumatic brain injury (TBI). As a result a series of neuroendocrine changes appear after head injury; in many occasions they reverse with time, while occasionally new late onset changes may develop.

AREAS COVERED

In this review, we focus on the prevalence of anterior and posterior pituitary hormonal changes in the acute and chronic post-TBI period in both children and adults. Moreover, we present evidence supporting the need for evaluating pituitary function along with the current suggestions for the most appropriate screening strategies. We attempted to identify all published literature and we conducted an online search of PubMed, from January 1970 to June 2020.

EXPERT OPINION

Adrenal insufficiency and water metabolism disorders are medical emergencies and should be promptly recognized. Awareness for long-term hormonal derangements is necessary, as they may lead to a series of chronic health issues and compromise quality of life. There is a need for well-designed prospective long-term studies that will estimate pituitary function during the acute and chronic phase after head injury.

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

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

Traumatic brain injury induced neuroendocrine changes: acute hormonal changes of anterior pituitary function

PURPOSE

It is estimated that approximately 69 million individuals worldwide will sustain a TBI each year, which accounts for substantial morbidity and mortality in both children and adults. TBI may lead to significant neuroendocrine changes, if the delicate pituitary is ruptured. In this review, we focus on the anterior pituitary hormonal changes in the acute post-TBI period and we present the evidence supporting the need for screening of anterior pituitary function in the early post-TBI time along with current suggestions regarding the endocrine assessment and management of these patients.

METHODS

Original systematic articles with prospective and/or retrospective design studies of acute TBI were included, as were review articles and case series.

RESULTS

Although TBI may motivate an acute increase of stress hormones, it may also generate a wide spectrum of anterior pituitary hormonal deficiencies. The frequency of post-traumatic anterior hypopituitarism (PTHP) varies according to the severity, the type of trauma, the time elapsed since injury, the study population, and the methodology used to diagnose pituitary hormone deficiency. Early neuroendocrine abnormalities may be transient, but additional late ones may also appear during the course of rehabilitation.

CONCLUSIONS

Acute hypocortisolism should be diagnosed and managed promptly, as it can be life-threatening, but currently there is no evidence to support treatment of acute GH, thyroid hormones or gonadotropins deficiencies. However, a more comprehensive assessment of anterior pituitary function should be undertaken both in the early and in the post-acute phase, since ongoing hormone deficiencies may adversely affect the recovery and quality of life of these patients.

Cortisol evaluation during the acute phase of traumatic brain injury-A prospective study

BACKGROUND

Biochemical diagnosis of adrenal insufficiency (AI) is difficult in the context of traumatic brain injury (TBI).

AIM

To assess the frequency and predictive factors of AI in victims of TBI from Algiers.

METHODS

Between November 2009 and December 2013, TBI victims had a single 8-9 am serum cortisol measurement during the acute postinjury period (0-7 days). AI was defined according to basal cortisol levels of 83, 276 and 414 nmol/L. Variables studied were TBI severity according to Glasgow coma scale, duration of intubation and coma, pupillary status, hypotension, anaemia, brain imaging findings, diabetes insipidus and medication. Insulin tolerance test was performed during the recovery phase, defining AI as peak cortisol <500 nmol/L.

RESULTS

Cortisol samples were obtained at median 3 (1-7) days from 277 patients (257M: 20F) aged 32 (18-65) years. Acute AI frequency was 8 (2.8%), 20 (21%) and 35 (37%), respectively using the three cortisol cut-offs. Factors predicting AI were diastolic hypotension, sedative medication, diabetes insipidus, skull base fracture and intraparenchymal haematoma. Mortality was highest in patients with acute cortisol <276 nmol/L (44.6% with OR for death 1.64, 95% CI 0.92-3.0, P = .12). During the recovery phase, AI was present in 3 of 3, 12 of 24, 4 of 16 and 20 of 66 patients with week 1 cortisol <83, 83-276, 277-414 and >414 nmol/L.

CONCLUSION

Hydrocortisone replacement is advised in TBI patients with morning cortisol <276 nmol/L or those <414 nmol/L with additional risk factors for AI. As acute and subsequent AI are poorly correlated, patients with moderate/severe TBI require adrenal re-evaluation during the recovery phase.

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.

Hyponatremia in Neurotrauma: The Role of Vasopressin

Hyponatremia is frequent in patients suffering from traumatic brain injury, subarachnoid hemorrhage, or following intracranial procedures, with approximately 20% having a decreased serum sodium concentration to <125 mmol/L. The pathophysiology of hyponatremia in neurotrauma is not completely understood, but in large part is explained by the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). The abnormal water and/or sodium handling creates an osmotic gradient promoting the shift of water into brain cells, thereby worsening cerebral edema and precipitating neurological deterioration. Unless hyponatremia is corrected promptly and effectively, morbidity and mortality increases through seizures, elevations in intracranial pressure, and/or herniation. The excess mortality in patients with severe hyponatremia (<125 mmol/L) extends beyond the time frame of hospital admission, with a reported mortality of 20% in hospital and 45% within 6 months of follow-up. Current options for the management of hyponatremia include fluid restriction, hypertonic saline, mineralocorticoids, and osmotic diuretics. However, the recent development of vasopressin receptor antagonists provides a more physiological tool for the management of excess water retention and consequent hyponatremia, such as occurs in SIADH. This review summarizes the existing literature on the pathophysiology, clinical features, and management of hyponatremia in the setting of neurotrauma.

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.

Role and Importance of IGF-1 in Traumatic Brain Injuries

It is increasingly affirmed that most of the long-term consequences of TBI are due to molecular and cellular changes occurring during the acute phase of the injury and which may, afterwards, persist or progress. Understanding how to prevent secondary damage and improve outcome in trauma patients, has been always a target of scientific interest. Plans of studies focused their attention on the posttraumatic neuroendocrine dysfunction in order to achieve a correlation between hormone blood level and TBI outcomes. The somatotropic axis (GH and IGF-1) seems to be the most affected, with different alterations between the acute and late phases. IGF-1 plays an important role in brain growth and development, and it is related to repair responses to damage for both the central and peripheral nervous system. The IGF-1 blood levels result prone to decrease during both the early and late phases after TBI. Despite this, experimental studies on animals have shown that the CNS responds to the injury upregulating the expression of IGF-1; thus it appears to be related to the secondary mechanisms of response to posttraumatic damage. We review the mechanisms involving IGF-1 in TBI, analyzing how its expression and metabolism may affect prognosis and outcome in head trauma patients.

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.

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.

Systemic manifestations of traumatic brain injury

Traumatic brain injury (TBI) affects functioning of various organ systems in the absence of concomitant non-neurologic organ injury or systemic infection. The systemic manifestations of TBI can be mild or severe and can present in the acute phase or during the recovery phase. Non-neurologic organ dysfunction can manifest following mild TBI or severe TBI. The pathophysiology of systemic manifestations following TBI is multifactorial and involves an effect on the autonomic nervous system, involvement of the hypothalamic-pituitary axis, release of inflammatory mediators, and treatment modalities used for TBI. Endocrine dysfunction, electrolyte imbalance, and respiratory manifestations are common following TBI. The influence of TBI on systemic immune response, coagulation cascade, cardiovascular system, gastrointestinal system, and other systems is becoming more evident through animal studies and clinical trials. Systemic manifestations can independently act as risk factors for mortality and morbidity following TBI. Some conditions like neurogenic pulmonary edema and disseminated intravascular coagulation can adversely affect the outcome. Early recognition and treatment of systemic manifestations may improve the clinical outcome following TBI. Further studies are required especially in the field of neuroimmunology to establish the role of various biochemical cascades, not only in the pathophysiology of TBI but also in its systemic manifestations and outcome.

Neurosurgical Hyponatremia

Hyponatremia is a frequent electrolyte imbalance in hospital inpatients. Acute onset hyponatremia is particularly common in patients who have undergone any type of brain insult, including traumatic brain injury, subarachnoid hemorrhage and brain tumors, and is a frequent complication of intracranial procedures. Acute hyponatremia is more clinically dangerous than chronic hyponatremia, as it creates an osmotic gradient between the brain and the plasma, which promotes the movement of water from the plasma into brain cells, causing cerebral edema and neurological compromise. Unless acute hyponatremia is corrected promptly and effectively, cerebral edema may manifest through impaired consciousness level, seizures, elevated intracranial pressure, and, potentially, death due to cerebral herniation. The pathophysiology of hyponatremia in neurotrauma is multifactorial, but most cases appear to be due to the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Classical treatment of SIADH with fluid restriction is frequently ineffective, and in some circumstances, such as following subarachnoid hemorrhage, contraindicated. However, the recently developed vasopressin receptor antagonist class of drugs provides a very useful tool in the management of neurosurgical SIADH. In this review, we summarize the existing literature on the clinical features, causes, and management of hyponatremia in the neurosurgical patient.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The 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.

Acute neuro-endocrine profile and prediction of outcome after severe brain injury

OBJECT

The aim of the study was to evaluate the early changes in pituitary hormone levels after severe traumatic brain injury (sTBI) and compare hormone levels to basic neuro-intensive care data, a systematic scoring of the CT-findings and to evaluate whether hormone changes are related to outcome.

METHODS

Prospective study, including consecutive patients, 15-70 years, with sTBI, Glasgow Coma Scale (GCS) score ≤ 8, initial cerebral perfusion pressure > 10 mm Hg, and arrival to our level one trauma university hospital within 24 hours after head trauma (n = 48). Serum samples were collected in the morning (08-10 am) day 1 and day 4 after sTBI for analysis of cortisol, growth hormone (GH), prolactin, insulin-like growth factor 1 (IGF-1), thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), follicular stimulating hormone (FSH), luteinizing hormone (LH), testosterone and sex hormone-binding globulin (SHBG) (men). Serum for cortisol and GH was also obtained in the evening (17-19 pm) at day 1 and day 4. The first CT of the brain was classified according to Marshall. Independent staff evaluated outcome at 3 months using GOS-E.

RESULTS

Profound changes were found for most pituitary-dependent hormones in the acute phase after sTBI, i.e. low levels of thyroid hormones, strong suppression of the pituitary-gonadal axis and increased levels of prolactin. The main findings of this study were: 1) A large proportion (54% day 1 and 70% day 4) of the patients showed morning s-cortisol levels below the proposed cut-off levels for critical illness related corticosteroid insufficiency (CIRCI), i.e. <276 nmol/L (=10 ug/dL), 2) Low s-cortisol was not associated with higher mortality or worse outcome at 3 months, 3) There was a significant association between early (day 1) and strong suppression of the pituitary-gonadal axis and improved survival and favorable functional outcome 3 months after sTBI, 4) Significantly lower levels of fT3 and TSH at day 4 in patients with a poor outcome at 3 months. 5) A higher Marshall CT score was associated with higher day 1 LH/FSH- and lower day 4 TSH levels 6) In general no significant correlation between GCS, ICP or CPP and hormone levels were detected. Only ICPmax and LH day 1 in men was significantly correlated.

CONCLUSION

Profound dynamic changes in hormone levels are found in the acute phase of sTBI. This is consistent with previous findings in different groups of critically ill patients, most of which are likely to be attributed to physiological adaptation to acute illness. Low cortisol levels were a common finding, and not associated with unfavorable outcome. A retained ability to a dynamic hormonal response, i.e. fast and strong suppression of the pituitary-gonadal axis (day 1) and ability to restore activity in the pituitary-thyroid axis (day 4) was associated with less severe injury according to CT-findings and favorable outcome.

Impact of head trauma on pituitary function

There have been in the past decade a growing number of studies relating head trauma to hypopituitarism. This condition may affect the rehabilitation process, and identification of such patients is therefore required. However, the widely different methods used so far for this purpose have provided inconsistent results. The incidence rate of hypopituitarism has probably been overestimated. This review focuses on the impact of head trauma on pituitary function, the diagnostic method, risk factors, and treatment options.

Pituitary dysfunction following traumatic brain injury or subarachnoid haemorrhage - in "Endocrine Management in the Intensive Care Unit"

Traumatic brain injury and subarachnoid haemorrhage are important causes of morbidity and mortality in the developed world. There is a large body of evidence that demonstrates that both conditions may adversely affect pituitary function in both the acute and chronic phases of recovery. Diagnosis of hypopituitarism and accurate treatment of pituitary disorders offers the opportunity to improve mortality and outcome in both traumatic brain injury and subarachnoid haemorrhage. In this article, we will review the history and pathophysiology of pituitary function in the acute phase following traumatic brain injury and subarachnoid haemorrhage, and we will discuss in detail three key aspects of pituitary dysfunction which occur in the early course of TBI; acute cortisol deficiency, diabetes insipidus and SIAD.

Acute gonadotroph and somatotroph hormonal suppression after traumatic brain injury

Hormonal dysfunction is a known consequence of moderate and severe traumatic brain injury (TBI). In this study we determined the incidence, time course, and clinical correlates of acute post-TBI gonadotroph and somatotroph dysfunction. Patients had daily measurement of serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone, estradiol, growth hormone, and insulin-like growth factor-1 (IGF-1) for up to 10 days post-injury. Values below the fifth percentile of a healthy cohort were considered abnormal, as were non-measurable growth hormone (GH) values. Outcome measures were frequency and time course of hormonal suppression, injury characteristics, and Glasgow Outcome Scale (GOS) score. The cohort consisted of 101 patients (82% males; mean age 35 years; Glasgow Coma Scale [GCS] score <or=8 in 87%). In men, 100% had at least one low testosterone value, and 93% of all values were low; in premenopausal women, 43% had at least one low estradiol value, and 39% of all values were low. Non-measurable GH levels occurred in 38% of patients, while low IGF-1 levels were observed in 77% of patients, but tended to normalize within 10 days. Multivariate analysis revealed associations of younger age with low FSH and low IGF-1, acute anemia with low IGF-1, and older age and higher body mass index (BMI) with low GH. Hormonal suppression was not predictive of GOS score. These results indicate that within 10 days of complicated mild, moderate, and severe TBI, testosterone suppression occurs in all men and estrogen suppression occurs in over 40% of women. Transient somatotroph suppression occurs in over 75% of patients. Although this acute neuroendocrine dysfunction may not be TBI-specific, low gonadal steroids, IGF-1, and GH may be important given their putative neuroprotective functions.

Hypogonadism after traumatic brain injury

Traumatic brain injury (TBI) is the most common cause of death and disability in young adults. Post-TBI neuroendocrine disorders have been increasingly acknowledged in recent years due to their potential contribution to morbidity and, probably, to mortality after trauma. Marked alterations of the hypothalamic-pituitary axis during the post-TBI acute and chronic phases have been reported. Prospective and longitudinal studies have shown that some abnormalities are transitory. On the other hand, there is a high frequency (15% to 68%) of pituitary hormone deficiency among TBI survivors in a long term setting. Post-TBI hypogonadism is a common finding after cranial trauma, and it is predicted to develop in 16% of the survivors in the long term. Post-TBI hypogonadism has been associated with adverse results in the acute and chronic phases after injury. These data reinforce the need for identification of hormonal deficiencies and their proper treatment, in order to optimize patient recovery, improve their life quality, and avoid the negative consequences of non-treated hypogonadism in the long term.

Acute Adrenal Insufficiency May Affect Outcome in the Trauma Patient

Acute adrenal insufficiency in the trauma patient is underrecognized and the impact poorly understood. Our hypothesis was that the identification and treatment of acute adrenal insufficiency reduces mortality in trauma patients. Institutional Review Board approval for the retrospective review of a prospective database from a Level 1 trauma center for 2002 to 2004 was obtained. The study population included patients receiving a cosyntropin stimulation test (250 μg) and/or random Cortisol level based on our practice management guideline and an intensive care unit stay longer than 24 hours. Demographic, acuity, and outcome data were collected. The nonresponders had baseline Cortisol levels less than 20 μg/dL or poststimulation rise less than 9 μg/dL. Independent t tests and χ2 statistics were used. One hundred thirty-seven patients had cosyntropin stimulation tests performed. Eighty-two (60%) patients were nonresponders of which 66 were treated with hydrocortisone and 16 went untreated as a result of the discretion of the attending physician. The 55 (40%) responders showed no statistical differences in outcome variables whether or not they received hydrocortisone. The untreated adrenal-insufficient patients had significantly higher mortality, longer hospital length of stay, intensive care unit days, and ventilator-free days. Conclusions were: 1) treatment of acute adrenal insufficiency reduces mortality by almost 50 per cent in the trauma patient; and 2) acute adrenal insufficiency recognized by low random Cortisol levels or nonresponse to a stimulation tests should be considered for treatment.

Clinical analysis of hyponatremia in acute craniocerebral injury

OBJECTIVE

To explore pathological mechanisms of central hyponatremia and its treatment.

METHODS

Synchronous assay was made for changes of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), endogenous digitalis-like substance (EDLS), antidiuretic hormone (ADH) in blood, and Na(+) concentrations in blood and urine, and plasma- and urine-osmolality in 68 patients with acute craniocerebral injury (ACI).

RESULTS

Of the 68 patients with ACI, 27 were found to have hyponatremia, and such illness was mostly concentrated on severe cases.

CONCLUSIONS

The central hyponatremia in patients with ACI may be related to the increase in the secretion of EDLS and ADH as the result of damaged functions of the hypothalamic-hypophysial system, and it seems that the decrease in blood ANP and BNP has no direct effect on Na(+) concentrations in blood. Inappropriate secretion of antidiuretic hormone syndrome and cerebral salt-wasting syndrome are the two main reasons for hyponatremia in patients with craniocerebral injury. The pathological mechanism, diagnostic standards, as well as treatment methods for the two, however, are not just the same. Intravenous injection of extrinsic thyrotropin-releasing hormone might inhibit dilutional hyponatremia arising from the increase in ADH secretion by patients with ACI.

Natriuretic Peptides, Antidiuretic Hormone and Hyponatraemia after Acute Craniocerebral Injury

We investigated the physiological mechanisms involved in central hyponatraemia in patients with acute craniocerebral injury (ACI). We measured blood concentrations of natriuretic peptides, antidiuretic hormone (ADH), and endogenous digitalis-like substance (EDLS), blood and urine sodium concentrations, and the plasma and urine osmolality in 68 patients with ACI and 24 healthy control subjects. A total of 27 ACI patients were hyponatraemic and the majority of these had grievous or severely grievous craniocerebral injuries. Blood concentrations of EDLS and ADH in hyponatraemic ACI patients were significantly higher compared with normonatraemic ACI patients and control subjects. Blood EDLS and sodium concentrations were negatively correlated with each other, whereas EDLS was positively correlated with urine sodium concentration and with urine osmotic pressure. Hyponatraemic ACI patients require different treatment based on the cause of their central hyponatraemia, so it is important to undertake a comprehensive analysis of each patient's physiological status.

Pituitary functions in the acute phase of traumatic brain injury: are they related to severity of the injury or mortality?

PRIMARY OBJECTIVE

There are only limited data regarding pituitary functions in the acute phase of traumatic brain injury (TBI) and previous studies have been conducted in only small cohorts of subjects. Therefore we have investigated the pituitary functions in the early acute phase, within 24 hours of trauma, in 104 patients with TBI. Additionally, the relationships between basal pituitary hormones, severity of the trauma and mortality due to trauma were also investigated.

METHODS AND PROCEDURES

One hundred and four TBI patients were included in the study consecutively. All patients underwent basal hormonal evaluation within the first 24 hours of admission. Twenty of 104 patients died during the acute phase.

MAIN OUTCOMES

Prolactin levels were negatively correlated with the Glasgow coma scale (GCS), cortisol levels were positively correlated with the GCS and cortisol levels were positively correlated with ACTH levels. Additionally there was a significant positive correlation between the total testosterone levels and the GCS in males. Logistic regression analysis revealed that mortality after TBI was unrelated to basal pituitary hormone levels. However age and GCS were significantly related to the mortality. The percentages of pituitary hormone deficiencies were as follows: 3.8% had TSH deficiency, 40.0% had gonadotrophin deficiency, 8.8% had ACTH deficiency and 20.0% had GH deficiency.

CONCLUSIONS

Present data clearly demonstrate that pituitary function is disturbed in TBI and the most frequently deficient pituitary hormones were gonadotrophins in the early acute phase of TBI. Basal hormone levels including cortisol, prolactin and total testosterone were related to the severity of the trauma. However there was no relation between basal hormones and mortality due to TBI. Age and GCS were significantly related to mortality.

Systemic illness

Systemic illnesses are associated with alterations in the hypothalamic-pituitary-peripheral hormone axes, which represent part of the adaptive response to stressful events and may be influenced by type and severity of illness and/or pharmacological therapy. The pituitary gland responds to an acute stressful event with two secretory patterns: adrenocorticotropin (ACTH), prolactin (PRL) and growth hormone (GH) levels increase, while luteinizing hormone (LH), follicle-stimulating hormone (FSH) and thyrotropin (TSH) levels may either decrease or remain unchanged, associated with a decreased activity of their target organ. In protracted critical illness, there is a uniformly reduced pulsatile secretion of ACTH, TSH, LH, PRL and GH, causing a reduction in serum levels of the respective target-hormones. These adaptations are initially protective; however, if inadequate or excessive they may be dangerous and may contribute to the high morbidity and mortality risk of these patients. There is no consensus regarding the type of approach, as well as the criteria to use to define pituitary axis function in critically ill patients. We here provide a critical approach to pituitary axis evaluation during systemic illness.

The effects of head trauma on hypothalamic-pituitary function in children and adolescents

PURPOSE OF REVIEW

Endocrine dysfunctions have been increasingly recognized following traumatic brain injury. Ever more numerous studies on acute head-injured adults have also raised concern about this risk in children and adolescents who have experienced head injury. The current review of the pediatric literature summarizes recent findings on acute-phase dysfunction and traumatic brain injury-associated hypopituitarism.

RECENT FINDINGS

The pathophysiologic mechanisms underlying acute-phase hyponatremic and hypernatremic disorders have been elucidated. Prospective studies on traumatic brain injury-associated hypopituitarism in pediatric patients are ongoing and preliminary data are available.

SUMMARY

Traumatic brain injury, a 'silent epidemic' that carries a considerable burden of disabilities, leads to a variety of endocrine dysfunctions in 28-69% of adult acute head-injured patients. In the acute posttraumatic phase, adrenal insufficiency and electrolyte disorders are critical conditions. Neurosurgical patients, particularly those prone to neurological damage, require prompt diagnosis. Hypopituitarism may be diagnosed months or years after a traumatic brain injury event. Since growth hormone and gonadotropin secretion are most frequently compromised, careful follow-up of growth and pubertal development is mandatory in children hospitalized for traumatic brain injury.

Hypopituitarism following traumatic brain injury (TBI)

Traumatic brain injury (TBI) is the commonest cause of death and disability in young adults living in industrialised countries. Recently, several studies have shown that hypopituitarism is a common complication of head trauma, with a prevalence of at least 25% among patients who were studied months or years following injury. This remarkably high frequency has changed the traditional concept of hypopituitarism being 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 have an important contribution to the high physical and neuropsychiatric morbidity seen in patients with head injury. This article discusses the published reports on neuroendocrine dysfunction in TBI patients and the natural history of this disorder. The potential impact of posttraumatic hypopituitarism on recovery and rehabilitation after injury will also be examined, as well as the need for the identification, and appropriate and timely management of hormone deficiencies in order to reduce morbidity, aid recovery, and avoid the long-term complications of pituitary failure.

Traumatic brain injury induced hypothalamic-pituitary dysfunction: a paediatric perspective

In survivors of traumatic brain injury (TBI), impairment in anterior pituitary hormone function may be an important cause of long-term morbidity. Histopathological evidence from post-mortem studies suggests that the hypothalamic-pituitary structures are vulnerable to damage following head injury. Pituitary dysfunction, present months or years after injury, is now well recognised in adults, however, little evidence is known about this potential complication in children and adolescents. This article reviews the available paediatric data, which shows that hypopituitarism may occur after both mild and severe TBI, with growth hormone and gonadotrophin deficiencies appearing to be most common abnormalities. Central precocious puberty has also been documented. There are, however, few published data within a population of children with TBI on the incidence or prevalence of hypopituitarism, nor on its natural history or response to hormone replacement, and prospective studies are needed. Given the critical role of anterior pituitary hormones in the regulation of growth, pubertal and neurocognitive development in childhood, early detection of hormone abnormalities following TBI is important. We propose that a multidisciplinary approach to follow-up and endocrine assessment is required for the long-term management and rehabilitation of children and adolescents who survive moderate to severe head injury.

Anterior pituitary dysfunction following traumatic brain injury (TBI)

Traumatic brain injury (TBI) is the commonest cause of death and disability in young adults living in industrialized countries. Several recent studies have convincingly shown that anterior hypopituitarism is a common complication of head trauma with a prevalence of at least 25% among long-term survivors. This is a much higher frequency than previously thought and suggests that most cases of post-traumatic hypopituitarism (PTHP) remain undiagnosed and untreated. These findings raise important questions about the potential contribution of PTHP to the high physical and neuropsychiatric morbidity seen in this group of patients. In this review, we examine the published reports on the neuroendocrine abnormalities in TBI patients and highlight new data that give novel insights into the natural history of this disorder. We discuss the potential contribution of PTHP to recovery and rehabilitation after injury and the need for the identification and the appropriate and timely management of hormone deficiencies to optimize patient recovery from head trauma, improve quality of life and avoid the long-term adverse consequences of untreated hypopituitarism.

Residual pituitary function after brain injury-induced hypopituitarism: a prospective 12-month study

CONTEXT

Traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH) are conditions at high risk for the development of hypopituitarism.

OBJECTIVE

The objective of the study was to clarify whether pituitary deficiencies and normal pituitary function recorded at 3 months would improve or worsen at 12 months after the brain injury.

DESIGN AND PATIENTS

Pituitary function was tested at 3 and 12 months in patients who had TBI (n = 70) or SAH (n = 32).

RESULTS

In TBI, the 3-month evaluation had shown hypopituitarism (H) in 32.8%. Panhypopituitarism (PH), multiple (MH), and isolated (IH) hypopituitarism had been demonstrated in 5.7, 5.7, and 21.4%, respectively. The retesting demonstrated some degree of H in 22.7%. PH, MH, and IH were present in 5.7, 4.2, and 12.8%, respectively. PH was always confirmed at 12 months, whereas MH and IH were confirmed in 25% only. In 5.5% of TBI with no deficit at 3 months, IH was recorded at retesting. In 13.3% of TBI with IH at 3 months, MH was demonstrated at 12-month retesting. In SAH, the 3-month evaluation had shown H in 46.8%. MH and IH had been demonstrated in 6.2 and 40.6%, respectively. The retesting demonstrated H in 37.5%. MH and IH were present in 6.2 and 31.3%, respectively. Although no MH was confirmed at 12 months, two patients with IH at 3 months showed MH at retesting; 30.7% of SAH with IH at 3 months displayed normal pituitary function at retesting. In SAH, normal pituitary function was always confirmed. In TBI and SAH, the most common deficit was always severe GH deficiency.

CONCLUSION

There is high risk for H in TBI and SAH patients. Early diagnosis of PH is always confirmed in the long term. Pituitary function in brain-injured patients may improve over time but, although rarely, may also worsen. Thus, brain-injured patients must undergo neuroendocrine follow-up over time.

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

BACKGROUND

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

DISCUSSION

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

CONCLUSIONS

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

Hypopituitarism after traumatic brain injury

Traumatic brain injury (TBI) is one of the main causes of death and disability in young adults, with consequences ranging from physical disabilities to long-term cognitive, behavioural, psychological and social defects. Post-traumatic hypopituitarism (PTHP) was recognized more than 80 years ago, but it was thought to be a rare occurrence. Recently, clinical evidence has demonstrated that TBI may frequently cause hypothalamic-pituitary dysfunction, probably contributing to a delayed or hampered recovery from TBI. Changes in pituitary hormone secretion may be observed during the acute phase post-TBI, representing part of the acute adaptive response to the injury. Moreover, diminished pituitary hormone secretion, caused by damage to the pituitary and/or hypothalamus, may occur at any time after TBI. PTHP is observed in about 40% of patients with a history of TBI, presenting as an isolated deficiency in most cases, and more rarely as complete pituitary failure. The most common alterations appear to be gonadotropin and somatotropin deficiency, followed by corticotropin and thyrotropin deficiency. Hyper- or hypoprolactinemia may also be present. Diabetes insipidus may be frequent in the early, acute phase post-TBI, but it is rarely permanent. Severity of TBI seems to be an important risk factor for developing PTHP; however, PTHP can also manifest after mild TBI. Accurate evaluation and long-term follow-up of all TBI patients are necessary in order to detect the occurrence of PTHP, regardless of clinical evidence for pituitary dysfunction. In order to improve outcome and quality of life of TBI patients, an adequate replacement therapy is of paramount importance.

Prevalence of hypopituitarism and growth hormone deficiency in adults long-term after severe traumatic brain injury

OBJECTIVE

Traumatic brain injury (TBI) has been associated with hypopituitarism and GH deficiency. However, TBI-mediated hypopituitarism may be more frequent than previously thought. The present work, performed in patients with severe TBI at least 1 year before, had three aims: (i) to evaluate the prevalence of hypopituitarism, (ii) in particular to evaluate the prevalence of GH deficiency, and (iii) to compare three different tests of GH reserve in this cohort.

DESIGN AND PATIENTS

From a nonselected group of 249 patients admitted to our Clinical Centre for severe TBI over the last 5 years, 200 of them answered a custom made questionnaire of symptoms of hypopituitarism enclosed in the invitation letter to participate in the study. A total of 170 (99 men and 14 women), accepted to participate in the study (study cohort); 57 had normal questionnaires and were not further studied, 14 discontinued the study, and 99 attended the hospital for dynamic tests of pituitary hormone deficiencies. From these, 44 subjects with IGF-I in the lower range were tested with GHRH+GHRP-6; ITT; and glucagon tests of GH reserve, on three different occasions.

MEASUREMENTS

Pituitary hormones plus IGF-I and target gland hormones were analysed.

RESULTS

With regard to the initial cohort of 170 subjects (100%), three (1.7%) showed diabetes insipidus; 10 (5.8%) TSH deficiency, 11 (6.4%) ACTH deficiency and 29 (17%) gonadotrophin deficiency. In 10 subjects (5.8%), GH deficiency was diagnosed by strict criteria. Finally, 15 (8.8%) showed combined deficit of several hormones.

CONCLUSION

After severe head trauma, gonadotrophin deficiency was the most common pituitary deficit. GH deficiency showed a prevalence similar to ACTH and TSH deficits, i.e. near 6% of the cohort. Taken together, 24.7% of the subjects studied showed any type of pituitary hormone deficiency.

Hypopituitarism and growth hormone deficiency in adult subjects after traumatic brain injury: who and when to test

Traumatic brain injury (TBI) was traditionally considered an infrequent cause of hypopituitarism. However recent reports strongly suggest that TBI-mediated pituitary hormones deficiency may well be more frequent than previously thought. As the prevalence of hypopituitarism is not dependent on the severity of the trauma and considering the high number of TBI events in all industrialized countries a screening procedure for detecting hormone deficiencies in all TBI patients is not possible. In the present work a suggestion for screening a subgroup of TBI patients is discussed in order to increase the effectiveness of the whole procedure.

Diabetes insipidus, secondary hypoadrenalism and hypothyroidism after traumatic brain injury: clinical implications

Adequate ADH secretion, adrenal and thyroid functions are vital during the acute and post-acute phases of TBI. Deficiencies of these functions as a result of TBI are increasingly recognized. During the acute phase of TBI the incidence of severe DI is 2.9%; the incidence of less severe forms of DI is 21.6-26%. The development of DI seems to correlate with the severity of trauma. In most occasions DI is transient, but persisting DI may develop with an incidence of 6.9-7.5% amongst TBI victims. The assessment of the adequacy of adrenal function during the acute phase of TBI remains a diagnostic challenge. A few studies demonstrated an incidence of hypoadrenalism of 15-16% during the early phase of TBI. It should be noted that early hypoadrenalism may be due to either a structural damage at the level of the hypothalamo-pituitary unit or it may develop in the context of the so-called "relative adrenal insufficiency", a functional abnormality that is currently increasingly recognized during the course of severe illness. Secondary hypoadrenalism during the late phases of TBI appears with an incidence of 7.1-12.7%. The "low-T3 syndrome" compromises the assessment of thyroid function during the acute phase of TBI; the incidence of TSH insufficiency during the recovery phase varies widely between 1-21%. In summary, diabetes insipidus, secondary hypoadrenalism and hypothyroidism may develop in a small albeit significant proportion of patients during the course of TBI. Therefore, assessment of the integrity of ADH secretion, hypothalamic-pituitary adrenal (HPA) axis and thyroid axis is crucial to ensure survival and optimal rehabilitation of TBI patients.

Occurrence of Pituitary Dysfunction following Traumatic Brain Injury

Traumatic brain injury (TBI) may be associated with impairment of pituitary hormone secretion, which may contribute to long-term physical, cognitive, and psychological disability. We studied the occurrence and risk factors of pituitary dysfunction, including growth hormone deficiency (GHD) in 50 patients (mean age 37.6 +/- 2.4 years; 40 males, age 20-60 years; 10 females, age 23-87 years) with TBI over 5 years. Cranial or facial fractures were documented in 12 patients, and neurosurgery was performed in 14. According to the Glasgow Coma Scale (GCS), 16 patients had suffered from mild, 7 moderate, and 27 severe TBI. Glasgow Outcome Scale (GOS) indicated severe disability in 5, moderate disability in 11, and good recovery in 34 cases. Basal pituitary hormone evaluation, performed once at times variable from 12 to 64 months after TBI, showed hypogonadotrophic hypogonadism in 7 (14%), central hypothyroidism in 5 (10%), low prolactin (PRL) levels in 4 (8%), and high PRL levels in 4 (8%) cases. All subjects had normal corticotrophic and posterior pituitary function. Seven patients showed low insulin-like growth factor-I (IGF-I) levels for age and sex. Results of GHRH plus arginine testing indicated partial GHD in 10 (20%) and severe GHD in 4 (8%) cases. Patients with GHD were older (p <0.05) than patients with normal GH secretion. Magnetic resonance imaging demonstrated pituitary abnormalities in 2 patients; altogether pituitary dysfunction was observed in 27 (54%) patients. Six patients (12%) showed a combination of multiple abnormalities. Occurrence of pituitary dysfunction was 37.5%, 57.1%, and 59.3% in the patients with mild, moderate, and severe TBI, respectively. GCS scores were significantly (p <0.02) lower in patients with pituitary dysfunction compared to those with normal pituitary function (8.3 +/- 0.5 vs. 10.2 +/- 0.6). No relationship was detected between pituitary dysfunction and years since TBI, type of injury, and outcome from TBI. In conclusion, subjects with a history of TBI frequently develop pituitary dysfunction, especially GHD. Therefore, evaluation of pituitary hormone secretion, including GH, should be included in the long-term follow-up of all TBI patients so that adequate hormone replacement therapy may be administered.

Neuroendocrine dysfunction in the acute phase of traumatic brain injury

BACKGROUND

Pituitary hormone abnormalities have been reported in up to 50% of survivors of traumatic brain injury (TBI) who were investigated several months or longer following the event. The frequency of pituitary dysfunction in the early post-TBI period is unknown.

AIM

To evaluate the prevalence of anterior and posterior pituitary dysfunction in the early phase following TBI.

SUBJECTS

Fifty consecutive patients admitted to the neurosurgical unit with severe or moderate TBI [initial Glasgow Coma Scale (GCS) score 3-13], and 31 matched healthy control volunteers were studied.

METHODS

The glucagon stimulation test (GST) was performed at a median of 12 days (range 7-20) following TBI. Baseline thyroid function, PRL, IGF-1, gonadotrophins, testosterone or oestradiol, plasma sodium, plasma and urine osmolalities or the standard observed water deprivation test were performed. The control subjects underwent the GST for GH and cortisol responses; other parameters were compared to locally derived reference ranges.

RESULTS

Control data indicated that peak serum GH of > 5 ng/ml and cortisol > 450 nmol/l following glucagon stimulation should be taken as normal. Nine TBI patients (18%) had GH response < 5 ng/ml (12 mU/l). Eight patients (16%) had peak cortisol responses < 450 nmol/l. Compared to controls, basal cortisol values were significantly lower in patients with subnormal cortisol responses to glucagon and significantly higher in patients with normal cortisol responses (P < 0.05). GH and cortisol deficiencies were unrelated to patient age, BMI, initial GCS or IGF-1 values (P > 0.05). Forty patients (80%) had gonadotrophin deficiency, with low sex steroid concentrations, which was unrelated to the presence of hyperprolactinaemia. In males there was a positive correlation between serum testosterone concentration and GCS (r = 0.32, P = 0.04). One patient had TSH deficiency. Hyperprolactinaemia was present in 26 patients (52%) and serum PRL levels correlated negatively with the GCS score (r =-0.36, P = 0.011). Thirteen patients (26%) had cranial diabetes insipidus (DI) and seven (14%) had syndrome of inappropriate ADH secretion.

CONCLUSION

Our data show that post-traumatic neuroendocrine abnormalities occur early and with high frequency, which may have significant implications for recovery and rehabilitation of TBI patients.

Endocrine abnormalities in critical care patients with moderate-to-severe head trauma: incidence, pattern and predisposing factors

OBJECTIVE

To investigate the incidence and type of endocrine abnormalities in critical care patients with traumatic brain injury (TBI) and to examine their relationships to possible predisposing factors.

DESIGN

Prospective study.

SETTING

General intensive care unit in a university hospital.

PATIENTS AND PARTICIPANTS

Thirty-four TBI patients (27 men, 7 women), having a mean age of 37+/-16 years, were studied after weaning from mechanical ventilation.

INTERVENTIONS

Baseline endocrine assessment was carried out by measuring cortisol, corticotropin, dehydroepiandrosterone sulfate, free thyroxine, thyrotropin (TSH), testosterone, oestradiol, follicle stimulating hormone (FSH), luteinizing hormone, prolactin, growth hormone and insulin-like growth factor I. Dynamic evaluation was performed by human corticotropin releasing hormone and growth hormone releasing hormone in all patients. Male patients underwent additional investigation with gonadotropin-releasing hormone. Severity of neurological derangement was graded according to Glasgow Coma Scale (GCS), Marshall Computerized Tomographic Classification and intracranial pressure (ICP) levels.

MEASUREMENTS AND RESULTS

Eighteen of the 34 patients (53%) had an abnormal result in at least one hormonal axis tested, with cortisol hyporesponsiveness and gonadal dysfunction being equally common, affecting 24% of patients. Endocrine abnormalities were associated with a higher brain CT-scan classification score ( p=0.02). The GCS on admission correlated positively with baseline FSH (r=0.37, p=0.03), peak FSH (r=0.41, p=0.03), testosterone (r=0.44, p=0.02) and TSH (r=0.39, p=0.03). There were no relations between ICP(max) and any baseline or dynamic hormone measurements.

CONCLUSIONS

Patients with TBI receiving critical care show changes in their neuroendocrine responses, which depend upon clinical and radiological measures of head injury severity. Most common abnormalities include cortisol hyporesponsiveness and hypogonadism.

Hypothalamic-pituitary-adrenal axis dysfunction in critically ill patients with traumatic brain injury: incidence, pathophysiology, and relationship to vasopressor dependence and peripheral interleukin-6 levels

OBJECTIVE

To investigate hypothalamic-pituitary-adrenal axis function in patients requiring mechanical ventilation for traumatic brain injury and to assess the relation of hypothalamic-pituitary-adrenal axis abnormalities with vasopressor dependence and peripheral cytokine levels.

DESIGN

Prospective study.

SETTING

General intensive care unit in a university teaching hospital.

PATIENTS

Forty patients (33 men and 7 women) with moderate to severe traumatic brain injury (mean age, 37 +/- 16 yrs) were studied the day after termination of mechanical ventilation (7-60 days after trauma).

INTERVENTIONS

First, a morning blood sample was obtained to measure baseline cortisol, corticotropin, interleukin-6, and tumor necrosis factor alpha. Subsequently, 1 microg of synthetic corticotropin was injected intravenously, and 30 mins later, a second blood sample was drawn to determine stimulated plasma cortisol. Based on data derived from healthy volunteers, patients having stimulated cortisol levels <18 microg/dL were defined as nonresponders to the low-dose stimulation test. Thirty-one patients underwent also a human corticotropin releasing hormone test.

MEASUREMENTS AND MAIN RESULTS

In traumatic brain injury patients, mean baseline and low-dose stimulation test-stimulated cortisol levels were 17.2 +/- 5.4 microg/dL and 24.0 +/- 6.6 microg/dL, respectively. The median increment in cortisol was 5.9 microg/dL. Basal corticotropin levels ranged from 3.9 to 118.5 pg/mL. Six of the 40 patients (15%) failed the low-dose stimulation test. The human corticotropin releasing hormone test (performed in 26 responders and five nonresponders) revealed diminished cortisol release only in the low-dose stimulation test nonresponder patients. Corticotropin responses to corticotropin releasing hormone were consistent with both primary (three patients) and/or secondary (two patients) adrenal dysfunction. In retrospect, nonresponders to the low-dose stimulation test more frequently required vasopressors (6/6 [100%] vs. 16/34 [47%]; p =.02) and for a longer time interval (median, 0 vs. 293 hrs; p =.006) compared with responders. Furthermore, nonresponders had higher interleukin-6 levels compared with responders (56.03 vs. 28.04 pg/mL; p =.01), whereas tumor necrosis factor alpha concentrations were similar in the two groups (2.42 vs. 1.55 pg/mL; p =.53).

CONCLUSIONS

Adrenal cortisol secretion after dynamic stimulation is deficient in a subset of critically ill patients with moderate to severe head injury. This disorder is associated with prior vasopressor dependency and higher interleukin-6 levels.

Upregulation of iNOS expression and phosphorylation of eIF-2alpha are paralleled by suppression of protein synthesis in rat hypothalamus in a closed head trauma model

When the inducible form of nitric oxide synthase (iNOS) is expressed after challenge to the nervous system, it results in abnormally high concentrations of nitric oxide (NO). Under such conditions, NO could phosphorylate the eukaryotic translation initiation factor (eIF)-2alpha, thus suppressing protein synthesis in neurons that play a role in endocrine and autonomic functions. Using the Marmarou model of traumatic brain injury (TBI), we observed a rapid increase (at 4 h after TBI) of iNOS mRNA in magno- and parvocellular supraoptic and paraventricular neurons, declining gradually by approximately 30% at 24 h and by approximately 80% at 48 h. Western analysis indicated a trend towards increased iNOS protein synthesis at 4 h, which peaked at 8 h, and tended to decrease at the later time points. At the same time points, we detected immunocytochemically the phosphorylated form of eIF-2alpha (eIF-2alpha[P]) as cytoplasmic and more often as nuclear labeling. The incidence of double-labeled [iNOS and eIF-2alpha(P)] neuronal profiles, particularly at 24 h and 48 h after TBI, was high. De novo protein synthesis assessed quantitatively after infusion of 35S methionine/cysteine was reduced by approximately 20% at 4 h, remained depressed at 24 h, and did not return to control levels up to 48 h following the trauma. The results suggest that iNOS may trigger phosphorylation of eIF-2alpha, which in turn interferes with protein synthesis at the translational (ribosomal complex) and transcriptional (chromatin) levels. The depression in protein synthesis may include downregulation of iNOS itself, which could be an autoregulatory inhibitory feedback mechanism for NO synthesis. Excessive amounts of NO may also participate in dysfunction of hypothalamic circuits that underlie endocrine and autonomic alterations following TBI.

The nutritional management of patients with head injuries

Severe head injuries tend to be associated with hypermetabolism and hypercatabolism resulting in negative nitrogen balances which may exceed 30 grams day-1. Enteral feeding should begin as soon as the patient is hemodynamically stable, attempting to reach a non-protein caloric intake of at least 30-35 kcal kg-1 day-1 and a protein intake of 2.0-2.5 g kg-1 day-1 as soon as possible. With severe head injuries (Glasgow Coma Scale < 8), there is an increased tendency for gastric feeding to regurgitate into the upper airway. Keeping the patient upright and checking residuals is important in such patients. Jejunal feedings are less apt to be aspirated. If it is apparent that the gastro-intestinal tract cannot be used to reach the nutritional goals within three days, total parental nutrition is begun within 24-48 h so as to reach these nutrition goals by either one or both routes by the third or fourth day. Blood glucose levels exceeding 150-200 mg dl-1 tend to increase the severity of the neurologic problems and efforts should be made to prevent hyperglycemia by carefully regulating the glucose and insulin intake. Indirect calorimetry to determine the respiratory quotient and resting energy expenditure should be determined twice weekly. To determine N2 balance, urinary urea nitrogen should be measured in 24-h specimens. These tests should be performed once or twice weekly until it is clear that the nutrition is adequate.

Hypopituitarism following traumatic brain injury and aneurysmal subarachnoid hemorrhage: a preliminary report

OBJECT

Recognition of pituitary hormonal insufficiencies after head injury and aneurysmal subarachnoid hemorrhage (SAH) may be important, especially given that hypopituitarism-related neurobehavioral problems are typically alleviated by hormone replacement. In this prospective study the authors sought to determine the rate and risk factors of pituitary dysfunction after head injury and SAH in patients at least 3 months after insult.

METHODS

Patients underwent dynamic anterior and posterior pituitary function testing. Results of the tests were compared with those of 18 age-, sex-, and body mass index-matched healthy volunteers. The 22 head-injured patients included 18 men and four women (mean age 28+/-10 years at the time of injury) with initial Glasgow Coma Scale (GCS) scores of 3 to 15. Eight patients (36.4%) had a subnormal response in at least one hormonal axis. Four were growth hormone (GH) deficient. Five patients (four men, all with normal testosterone levels, and one woman with a low estradiol level) exhibited an inadequate gonadotroph response. One patient had both GH and thyrotroph deficiency and another had both GH deficiency and borderline cortisol deficiency. At the time of injury, all eight patients with pituitary dysfunction had an initial GCS score of 10 or less and, compared with the 14 patients without dysfunction, were more likely to have had diffuse swelling, seen on initial computerized tomography scans (p < 0.05), and to have sustained a hypotensive or hypoxic insult (p = 0.07). Of two patients with SAH who were studied (Hunt and Hess Grade IV) both had GH deficiency.

CONCLUSIONS

From this preliminary study, some degree of hypopituitarism appears to occur in approximately 40% of patients with moderate or severe head injury, with GH and gonadotroph deficiencies being most common. A high degree of injury severity and secondary cerebral insults are likely risk factors for hypopituitarism. Pituitary dysfunction also occurs in patients with poor-grade aneurysms. Postacute pituitary function testing may be warranted in most patients with moderate or severe head injury, particularly those with diffuse brain swelling and those sustaining hypotensive or hypoxic insults. The neurobehavioral effects of GH replacement in patients suffering from head injury or SAH warrant further study.

Limits of intermittent jugular bulb oxygen saturation monitoring in the management of severe head trauma patients

OBJECTIVE

To evaluate, in a prospective, observational study, whether bilateral monitoring of jugular bulb oxyhemoglobin saturation (SjO2), in addition to standard monitoring, results in modification of the management of severe head trauma.

METHODS

The patients underwent bilateral jugular bulb cannulation and observation at 8-hour intervals, during which SjO2 was measured and the neurological condition and physiological variables were assessed. The study group was responsible for evaluating whether the physician's decision-making process was influenced by the detection of SjO2 abnormalities. The SjO2 discrepancy in simultaneous bilateral samples was also evaluated to determine whether it interfered with the interpretation of data and with clinical decision-making. The SjO2-related complications were monitored.

RESULTS

Thirty patients underwent 319 observations. In 96% of patients, SjO2 was normal or high and had no influence on the diagnostic or therapeutic strategies. Treatment decisions were dictated by changes in clinical status and in intracranial and cerebral perfusion pressure. When these parameters were abnormal, treatment was administered, even if SjO2 was normal (101 observations). Conversely, when SjO2 was the only detected abnormality (34 observations), no treatment was administered. Abnormally low SjO2 values, caused by hypovolemia and hypocapnia, were detected in 3.4% of observations and actually modified the management. The discrepancies in simultaneous bilateral samples were substantial and gave rise to relevant interpretation problems. Fifteen percent of jugular catheters showed evidence of bacterial colonization.

CONCLUSION

Intermittent SjO2 monitoring did not substantially influence the management of severe head trauma. Therefore, recommendation for its routine use in all patients seems inadvisable, and indications for this invasive method should no longer be defined on the basis of experts' opinions, but rather on randomized, prospective studies.