Posterior pituitary dysfunction following traumatic brain injury: review

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.

Suspected cerebral salt wasting syndrome secondary to traumatic brain injury in a dog

OBJECTIVE

To describe a dog with suspected cerebral salt wasting syndrome (CSWS) secondary to traumatic brain injury (TBI).

CASE SUMMARY

A 2-month-old intact male Chihuahua-American Pitbull Terrier mix weighing 1.94 kg presented to a veterinary teaching emergency room after suffering bite wound-penetrating trauma to the head. Treatment was initiated with hyperosmotic agents, fluid resuscitation, and analgesia. The dog's neurologic dysfunction warranted hospitalization and continuous monitoring. Within 24 hours, the dog developed hyponatremia (133 mmol/L compared to 143 mmol/L on presentation [reference interval 142-149 mmol/L]). As the dog had concurrent tachycardia, increase in urine sodium concentration, polyuria, and weight loss, a diagnosis of cerebral salt wasting was suspected. A 2% hypertonic saline constant rate infusion was administered for volume replacement, and the patient showed improvement in clinical signs and blood sodium concentration. The dog was discharged on Day 5. Recheck examination showed significant neurologic improvement with sodium just below the low end of the reference range (141 mmol/L [reference interval 142-149 mmol/L]).

NEW OR UNIQUE INFORMATION PROVIDED

This is the first description of suspected CSWS in veterinary medicine. Hyponatremia is a common finding in critically ill neurologic people, including those with TBI, and is typically associated with either syndrome of inappropriate antidiuretic hormone or CSWS. As treatment recommendations for syndrome of inappropriate antidiuretic hormone and CSWS are diametrically opposed, identifying the presence of hyponatremia and distinguishing between these 2 clinical entities is critical for improving patient care for those with TBI. This case highlights the characteristics and clinical progression regarding the diagnosis and management of suspected CSWS.

Medical, Neurologic, and Neuromusculoskeletal Complications

For patients with disorders of consciousness (DoC), treating the medical, neurologic, and neuromuscular complications not only stabilizes their medical disturbances, but minimizes confounding factors that may obscure the ability to accurately identify the level of consciousness and increase the chance of patients' neurologic and functional recovery. Lack of reliable communication and low-level function of patients with DoC make it challenging to diagnose some of the complications. Skilled clinical observation will be imperative to appropriately care for the patients.

Paediatric perspectives in the diagnosis of polyuria-polydipsia syndrome

The elucidation of the underlying cause of polyuria-polydipsia syndrome (PPS) is a challenging-especially in the differentiation of partial defects of arginine vasopressin (AVP) secretion or action from primary polydipsia. The water deprivation test has been utilized for many decades, and its application in the paediatric population has been applied using parameters predominantly established in adult cohorts. In more recent times, the development of automated commercial assays for copeptin, a surrogate marker for AVP, has represented a significant advancement in the diagnostic approach to PPS. Measurement of copeptin concentrations has major advantages and has essentially superseded measurement of AVP in diagnostic protocols for PPS. Additionally, stimulated-copeptin protocols utilizing hypertonic saline infusion, arginine, and glucagon have been investigated, and are promising. However, further studies are required in the population-incorporating the differences in physiological regulation of water homeostasis, and safety requirements-before there is widespread adoption into clinical practice.

Diagnostic Significance of Combined Calcitoninogen, Platelet, and D-Dimer Assay in Severe Heatstroke: with Clinical Data Analysis of 70 Patients with Severe Heatstroke

The significance of calcitoninogen detection among inpatients was discussed by analyzing the clinical characteristics of severe heatstroke (HS). HS patients who were admitted to the Second Hospital of Nantong University, Jiangsu Province, China, between July 1, 2015, and October 30, 2020, were reviewed. Patients' clinical characteristics and laboratory data were recorded, and they were divided into three groups, that is, a control group (heat cramps and heat exhaustion), an exertional HS (EHS) group, and a classical HS (CHS) group to compare the differences among them. Receiver operating characteristic (ROC) curves were plotted to evaluate patients' clinical utility. (1) The body temperatures in the EHS and CHS groups were significantly higher than in the control group (all p < 0.05). (2) The D-dimer (DD), procalcitonin (PCT), and Acute Physiology and Chronic Health Evaluation (APACHE) II score of the EHS group were significantly higher compared with the control and CHS groups (all p < 0.05); the platelets (PLT), C-reactive protein (CRP), blood sodium (Na), and intravenous glucose (GLU) of the EHS group were lower than in the control and CHS groups (all p < 0.05). (3) The ROC curve analysis showed the performance results for DD (area under the curve [AUC] 0.670, 95% confidence interval [CI] 0.547-0.777), PCT (AUC 0.705, 95% CI 0.584-0.808), and PLT (AUC 0.791, 95% CI 0.677-0.879). The sensitivity was 40.48%, 100%, and 73.81%, and the specificity was 96.43%, 32.14%, and 78.57%, respectively. Using three combined analyses, an elevated AUC of 0.838, 95% CI 0.731-0.916, with a sensitivity of 71.43% and a specificity of 85.71%, respectively, was revealed. Patients in the EHS group had higher DD, PCT, and APACHE II values, whereas PLT, CRP, Na, and GLU were reduced. The apparent decrease in the PLT, as well as the increase in PCT and DD values, could be considered as early sensitivity indicators of severe HS. A combined test of these three indicators presented significant diagnostic value for detecting severe cases of HS.

Diagnosis and Management of Central Diabetes Insipidus in Adults

Central diabetes insipidus (CDI) is a clinical syndrome which results from loss or impaired function of vasopressinergic neurons in the hypothalamus/posterior pituitary, resulting in impaired synthesis and/or secretion of arginine vasopressin (AVP). AVP deficiency leads to the inability to concentrate urine and excessive renal water losses, resulting in a clinical syndrome of hypotonic polyuria with compensatory thirst. CDI is caused by diverse etiologies, although it typically develops due to neoplastic, traumatic, or autoimmune destruction of AVP-synthesizing/secreting neurons. This review focuses on the diagnosis and management of CDI, providing insights into the physiological disturbances underpinning the syndrome. Recent developments in diagnostic techniques, particularly the development of the copeptin assay, have improved accuracy and acceptability of the diagnostic approach to the hypotonic polyuria syndrome. We discuss the management of CDI with particular emphasis on management of fluid intake and pharmacological replacement of AVP. Specific clinical syndromes such as adipsic diabetes insipidus and diabetes insipidus in pregnancy as well as management of the perioperative patient with diabetes insipidus are also discussed.

Brain Trauma, Glucocorticoids and Neuroinflammation: Dangerous Liaisons for the Hippocampus

Glucocorticoid-dependent mechanisms of inflammation-mediated distant hippocampal damage are discussed with a focus on the consequences of traumatic brain injury. The effects of glucocorticoids on specific neuronal populations in the hippocampus depend on their concentration, duration of exposure and cell type. Previous stress and elevated level of glucocorticoids prior to pro-inflammatory impact, as well as long-term though moderate elevation of glucocorticoids, may inflate pro-inflammatory effects. Glucocorticoid-mediated long-lasting neuronal circuit changes in the hippocampus after brain trauma are involved in late post-traumatic pathology development, such as epilepsy, depression and cognitive impairment. Complex and diverse actions of the hypothalamic–pituitary–adrenal axis on neuroinflammation may be essential for late post-traumatic pathology. These mechanisms are applicable to remote hippocampal damage occurring after other types of focal brain damage (stroke, epilepsy) or central nervous system diseases without obvious focal injury. Thus, the liaisons of excessive glucocorticoids/dysfunctional hypothalamic–pituitary–adrenal axis with neuroinflammation, dangerous to the hippocampus, may be crucial to distant hippocampal damage in many brain diseases. Taking into account that the hippocampus controls both the cognitive functions and the emotional state, further research on potential links between glucocorticoid signaling and inflammatory processes in the brain and respective mechanisms is vital.

Permanent central diabetes insipidus after traumatic brain injury. Case report and literature review

The authors report permanent central diabetes insipidus (CDI) in a patient after severe traumatic brain injury (TBI) in traffic accident. A 16-year-old boy entered to a medical facility in coma (GCS score 6) with the following diagnosis: acute TBI, severe cerebral contusion, subarachnoid hemorrhage, depressed comminuted cranial vault fracture, basilar skull fracture, visceral contusion. CDI was diagnosed in 3 days after injury considering polyuria and hypernatremia (155 mmol/l). Desmopressin therapy was initiated through a feeding tube. Thirst appeared when a patient came out of the coma after 21 days despite ongoing desmopressin therapy. Considering persistent thirst and polyuria, we continued desmopressin therapy in a spray form. Under this therapy, polyuria reduced to 3-3.5 liters per a day. Symptoms of CDI persisted in long-term period (2 years after TBI) while function of adenohypophysis was intact. This case demonstrates a rare development of permanent diabetes insipidus after TBI. CDI manifested only as polyuria and hypernatremia in coma. Thirst joined after recovery of consciousness. Probable causes of CDI were damage to neurohypophysis and partially injury of pituitary stalk because of extended basilar skull fracture and/or irreversible secondary lesion of hypothalamus following diffuse axonal damage after TBI.

Diabetes insipidus

Diabetes insipidus (DI) is a disorder characterized by a high hypotonic urinary output of more than 50ml per kg body weight per 24 hours, with associated polydipsia of more than 3 liters a day [1,2]. Central DI results from inadequate secretion and usually deficient synthesis of Arginine vasopressin (AVP) in the hypothalamus or pituitary gland. Besides central DI further underlying etiologies of DI can be due to other primary forms (renal origin) or secondary forms of polyuria (resulting from primary polydipsia). All these forms belong to the Polyuria Polydipsia Syndrom (PPS). In most cases central and nephrogenic DI are acquired, but there are also congenital forms caused by genetic mutations of the AVP gene (central DI) [3] or by mutations in the gene for the AVP V2R or the AQP2 water channel (nephrogenic DI) [4]. Primary polydipsia (PP) as secondary form of polyuria includes an excessive intake of large amounts of fluid leading to polyuria in the presence of intact AVP secretion and appropriate antidiuretic renal response. Differentiation between the three mentioned entities is difficult [5], especially in patients with Primary polydipsia or partial, mild forms of DI [1,6], but different tests for differential diagnosis, most recently based on measurement of copeptin, and a thorough medical history mostly lead to the correct diagnosis. This is important since treatment strategies vary and application of the wrong treatment can be dangerous [7]. Treatment of central DI consists of fluid management and drug therapy with the synthetic AVP analogue Desmopressin (DDAVP), that is used as nasal or oral preparation in most cases. Main side effect can be dilutional hyponatremia [8]. In this review we will focus on central diabetes insipidus and describe the prevalence, the clinical manifestations, the etiology as well as the differential diagnosis and management of central diabetes insipidus in the out- and inpatient setting.

Role of copeptin in the diagnosis of traumatic neuroendocrine dysfunction

Traumatic neuroendocrine dysfunction may present with diabetes insipidus (DI) or with the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Both these pathologies involve a disturbance in the antidiuretic hormone (ADH) secretion, causing dysnatremias. Diagnosis of posttraumatic ADH dysfunction is hampered by technical difficulties in ADH assessment, and relies mostly on non-specific serum sodium, serum and urine osmolality and diuresis, often leading to misdiagnosis in the acute care setting. Research now focuses on the diagnostic role of copeptin, a peptide secreted together with ADH in an equimolar fashion, and which can be accurately evaluated. Recent studies identified cut-off values of 2.6 pmol/L for baseline copeptin and of 4.9 and 3.8 pmol/L for hypertonic saline infusion and arginine infusion stimulated copeptin, respectively, for the diagnosis of DI in patients with polyuria-polydipsia syndrome. Although SIADH is more difficult to be explored due to its heterogeneity, a ratio of copeptin to urinary sodium below 30 pmol/mmol identifies euvolemic hyponatremia. Exploring the role of copeptin assessment in patients with traumatic brain injury (TBI) in the acute phase may improve their diagnosis accuracy, management and outcome.

Potential Use of Pharmacogenetics to Reduce Drug-Induced Syndrome of Inappropriate Antidiuretic Hormone (SIADH)

Syndrome of inappropriate antidiuretic hormone (SIADH) is a common cause of hyponatremia, and many cases represent adverse reactions to drugs that alter ion channel conductance within the peptidergic nerve terminals of the posterior pituitary. The frequency of drug-induced SIADH increases with age; as many as 20% of patients residing in nursing homes have serum sodium levels below 135 mEq/L. Mild hyponatremia is associated with cognitive changes, gait instability, and falls. Severe hyponatremia is associated with cerebral edema, seizures, permanent disability, and/or death. Although pharmacogenetic tests are now being deployed for some drugs capable of causing SIADH (e.g., antidepressants, antipsychotics, and opioid analgesics), the implementation of these tests has been based upon the prior known association of these drugs with other serious adverse drug reactions (e.g., electrocardiographic abnormalities). Work is needed in large observational cohorts to quantify the strength of association between pharmacogene variants and drug-induced SIADH so that decision support can be developed to identify patients at high risk.

Late magnetic resonance imaging findings in trauma-induced central diabetes insipidus: Case report and review of literature

We presented the late magnetic resonance imaging characteristics in a 47-year-old male who diagnosed with a permanent trauma-induced diabetes insipidus. The patient developed polyuria following a deceleration injury which has been diagnosed as central diabetes insipidus based on the water deprivation test. Computed tomography or magnetic resonance evaluation of the pituitary gland is usually normal in such cases. Therefore, negative imaging studies do not exclude the diagnosis. However, MRI is more sensitive and can depict subtle injuries of the hypothalamus-pituitary axis in acute and late phases. The late MR imaging findings are not well established. To the best of our knowledge, this will be the first report to describe the late MR imaging features in a permanent case of trauma-induced diabetes insipidus.

Prognostic value of admission serum glucose-phosphate ratio in predicting the 6-month outcome of patients with severe traumatic brain injury: A retrospective study

BACKGROUND

Serum glucose-phosphate ratio has been revealed to be associated with severity and prognosis of aneurysmal subarachnoid hemorrhage. Objective of this study was to investigate the relationship between serum glucose-phosphate ratio and severe traumatic brain injury outcome.

METHODS

Patients with severe traumatic brain injury were stratified in quartiles according to their serum glucose-phosphate ratio. Outcome parameters included mortality, overall survival and poor outcome defined as Glasgow outcome scale score of 1-3 at post-traumatic 6 months. Multiple logistic regression analysis was performed to evaluate the association between quartiles of serum glucose-phosphate ratio and outcome.

RESULTS

Data from 105 patients were retrospectively reviewed. Glasgow coma scale score declined, Glasgow outcome scale score decreased, Rotterdam computed tomography classification were raised, mortality increased, overall survival probability reduced and percentage of poor outcome rose significantly with each quartile of serum glucose-phosphate ratio. After adjusting for other confounding factors, serum glucose-phosphate ratio according to quartiles was substantially related to 6-month mortality, overall survival and poor outcome. Under receiver operating characteristic curve, serum glucose-phosphate ratio showed a significantly high prognostic predictive capability.

CONCLUSIONS

Serum glucose-phosphate ratio might be a potential variable that can reflect trauma severity and prognosis in patients with severe traumatic brain injury.

Management of central diabetes insipidus

The treatment of central diabetes insipidus has not changed significantly in recent decades, and dDAVP and replacement of free water deficit remain the cornerstones of treatment. Oral dDAVP has replaced nasal dDAVP as a more reliable mode of treatment for chronic central diabetes insipidus. Hyponatraemia is a common side effect, occurring in one in four patients, and should be avoided by allowing a regular break from dDAVP to allow a resultant aquaresis. Hypernatraemia is less common, and typically occurs during hospitalization, when access to water is restricted, and in cases of adipsic DI. Management of adipsic DI can be challenging, and requires initial inpatient assessment to establish dose of dDAVP, daily fluid prescription, and eunatraemic weight which can guide day-to-day fluid targets in the long-term.

Central diabetes insipidus in children: Diagnosis and management

Central diabetes insipidus (CDI) is a complex disorder in which large volumes of dilute urine are excreted due to arginine-vasopressin deficiency, and it is caused by a variety of conditions (genetic, congenital, inflammatory, neoplastic, traumatic) that arise mainly from the hypothalamus. The differential diagnosis between diseases presenting with polyuria and polydipsia is challenging and requires a detailed medical history, physical examination, biochemical approach, imaging studies and, in some cases, histological confirmation. Magnetic resonance imaging is the gold standard method for evaluating the sellar-suprasellar region in CDI. Pituitary stalk size at presentation is variable and can change over time, depending on the underlying condition, and other brain areas or other organs - in specific diseases - may become involved during follow up. An early diagnosis and treatment are preferable in order to avoid central nervous system damage and the risk of dissemination of germ cell tumor, or progression of Langerhans Cell Histiocytosis, and in order to start treatment of additional pituitary defects without further delay. This review focuses on current diagnostic work-up and on the role of neuroimaging in the differential diagnosis of CDI in children and adolescents. It provides an update on the best approach for diagnosis - including novel biochemical markers such as copeptin - treatment and follow up of children and adolescents with CDI; it also describes the best approach to challenging situations such as post-surgical patients, adipsic patients, patients undergoing chemotherapy and/or in critical care.

Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH): Optimal Management

Hyponatremia, defined as serum sodium concentration <135 mEq/l, is the most common electrolyte balance disorder in clinical practice. Many causes are listed, but syndrome of inappropriate antidiuretic hormone secretion (SIADH) is certainly the most relevant, mainly in oncological and hospitalized patients. In this review, the pathophysiological and clinical aspects are described in detail. Patients’ extensive medical history and structured physical and biochemical tests are considered the milestones marking the way of the SIADH management as to provide early detection and proper correction. We focused our attention on the poor prognostic role and negative effect on patient’s quality of life of SIADH-induced hyponatremia in both malignant and non-malignant settings, stressing how optimal management of this electrolyte imbalance can result in improved outcomes and lower health costs.

Psychogenic Adipsia Presenting as Recurrent Functional Vomiting and Hypernatremia

Hypernatremia is caused by a disproportionate balance of inadequate free water relative to sodium level. Frequent causes of hypernatremia include renal or gastrointestinal fluid loss, hypothalamic injury, and endocrine abnormalities. The authors describe a rare case of hypernatremia that manifested secondary to psychogenic adipsia in a 46-year-old woman presenting with intractable vomiting. Her presenting symptoms and laboratory abnormalities resolved after treatment was initiated for major depression. This case highlights the need for a holistic approach when confronted with a case of unexplained hypernatremia.

Successful Treatment of Transient Central Diabetes Insipidus following Traumatic Brain Injury in a Dog

An 11-year-old female spayed Maltese presented comatose, half an hour after vehicular trauma, and was treated for traumatic brain injury and pulmonary contusions. The dog developed severe hypernatremia within six hours of presentation, which responded poorly to the administration of five percent dextrose in water. As central diabetes insipidus was suspected, desmopressin was trialled and resolution of hypernatremia was achieved six days later. Transient trauma-induced central diabetes insipidus has been described previously in two dogs; in the first, serum sodium concentrations were evaluated three days after injury and the other developed hypernatremia seven days after injury. To the authors' knowledge, this is the first report of rapid onset, transient, and trauma-induced central diabetes insipidus in a dog that encompasses the complete clinical progression of the syndrome from shortly after injury through to resolution.

Permanent central diabetes insipidus after mild head injury

We report a case of a patient with mild traumatic brain injury (TBI) who was diagnosed with permanent central diabetes insipidus (DI). A 21-year-old man was admitted to our outpatient clinic with polyuria and polydipsia 1 week after a mild head injury. He was well, except for these complaints. The initial laboratory workup was consistent with DI. There was no abnormality with other laboratory and hormone values. MRI showed lack of neurohypophyseal hyperintensity with no other abnormal findings. The patient responded well to desmopressin therapy. At the first year of the diagnosis, the patient still needed to use desmopressin treatment as we concluded that DI is permanent. DI is not uncommon after TBI, but it is often seen after severe TBI. We present here an extraordinary case of developing permanent DI after mild TBI with the absence of neurohypophyseal bright spot on MRI with no other abnormal findings.