Thyroid function in the subacute phase of traumatic brain injury: a potential predictor of post-traumatic neurological and functional outcomes

Endocrine dysfunction post-traumatic brain injury: challenges and therapeutic approaches

Traumatic brain injury (TBI) is a widespread, serious public health concern with substantial lasting effects, such as impacting the endocrine system. Here, we review the complications and consequences of TBI on the hypothalamic-pituitary axis (HPA) and connected endocrine glands, which are essential for maintaining body balance. Endocrine dysfunctions caused by TBI, especially hypopituitarism, can result in hormonal imbalances that impact various physiological systems, such as growth, metabolism, reproduction, and stress responses. These dysfunctions can cause issues like adrenal insufficiency, hypothyroidism, and hypogonadism, greatly affecting the quality of life of survivors. In cases of moderate to severe TBI, up to 40% of individuals may suffer from post-TBI hypopituitarism, leading to extended morbidity. The introduced treatment methods concentrate on different therapeutic options, including hormone replacement therapies (HRTs) (corticosteroid, growth, thyroid, and sex hormones replacement therapies), emerging plant-based bioactive compounds, and other options to address particular deficiencies. Simultaneously, there is a growing interest in novel bioactive compounds derived from plants because of their neuroprotective and anti-inflammatory properties. In addition, certain populations, such as veterans and children, are more likely to develop endocrine dysfunction due to TBI. Comprehensive, cross-disciplinary care and individualized treatment plans are crucial to improve outcomes and long-term recovery for TBI patients. Further investigation is needed to enhance diagnostic instruments, explore novel therapies, and establish predictive biomarkers for early intervention in TBI-induced endocrine disorders.

The interplay between thyrotropic axis, neurological complications, and rehabilitation outcomes in patients with traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of mortality and long-term disability, with its pathophysiology encompassing both primary mechanical damage and secondary neuroinflammatory, metabolic, and biochemical alterations. These complex mechanisms contribute to the observed heterogeneous clinical outcomes, including neuroendocrine dysfunctions, post-traumatic seizures, and disorders of consciousness (DoC). Thyroid hormones (THs) play essential roles in synaptic plasticity, neurogenesis and neuronal homeostasis, and the hypothalamic-pituitary-thyroid (HPT) axis has recently emerged as a potential acute and chronic modulator of neurological and functional recovery following TBI, thereby hinting at the potential involvement of THs in post-TBI outcomes. While evidence suggests that alterations in the HPT axis may influence susceptibility to seizures, progression of DoC, and rehabilitation outcomes, an increased blood-brain barrier permeability in concert with dysregulated deiodinase activity and expanding oxidative stress have all been proposed as mechanisms linking THs to post-TBI neurological complications. This review aims to summarize current evidence on the potential role of the thyrotropic axis in neurological and rehabilitation outcomes following TBI.

Thyroid hormones and prognosis in adults with status epilepticus: a retrospective study

Objectives

Thyroid hormone levels have been indicated to be associated with the functional outcome in critical illness. However, the studies on thyroid hormones and status epilepticus (SE) are rare. This study aimed to evaluate the predictive value of serum thyroid hormone levels on admission for unfavorable outcome in adult patients with SE.

Methods

We investigated and validated the predictive value of serum thyroid hormone levels on admission for the prognosis of adult SE patients. We extracted the clinical information and outcomes of patients. Modified Rankin scale (mRS) scores were applied to assess the patients' functional outcome, and mortality at 30 days after SE onset was identified. Serum levels of thyroid hormones including free thyroxin (FT4), free triiodothyronine (FT3) and thyroid-stimulating hormone (TSH) were detected on admission.

Results

We first analyzed the discovery cohort of 87 patients with SE. We found that 35.6% (31/87) of the patients had a poor outcome at discharge, and 18.4% (16/87) of the patients died during hospital stay and at 30-day follow up. The serum FT3 levels in the non-survivors group were significantly lower than those in the survivors group. Low T3 syndrome occurred in 29.9% (26/87) of SE cases and patients with low T3 syndrome were more likely to have unfavorable outcomes. Furthermore, we observed similar results in the external cohort, which validated our findings.

Conclusions

Serum FT3 levels measured on admission are independently associated with 30-day mortality in SE patients. Additionally, low T3 syndrome may be a promising candidate for predicting SE prognosis.

Advances in serum thyroid hormone levels and seizures

Epilepsy, a common neurological disorder, is characterized by paroxysmal, short-term, repetitive, and stereotypical features, significantly impacting patients' quality of life. Currently, the pathogenesis of epilepsy remains incompletely understood. Changes in neuronal excitability, imbalances in glutamate and gamma-aminobutyric acid (GABA) levels, alterations in the activity of GABA receptors, and dysfunction of GABA receptors are considered closely related to its occurrence. Thyroid hormones, vital for human growth and development, also play a crucial role in the nervous system. They mediate oxidative stress, influence reactive oxygen species production, affect mitochondrial function and neuronal excitability, and modulate glutamate and GABA levels. Also, they combine with thyroid hormone receptors and exert genomic effects by regulating the expression of numerous genes. However, once there are defects in thyroid hormone signaling, these defects may lead to severe neurodevelopmental disorders that are associated with an increased frequency of seizures. The impact of antiseizure medications (ASMs) on serum thyroid hormone levels, particularly traditional ASMs, has been extensively studied. It is reported that conventional ASMs such as phenobarbital, phenytoin sodium, carbamazepine, and valproate sodium were more likely to induce subclinical hypothyroidism (elevated TSH with normal FT4) or isolated hypothyroidism (decreased FT4 with normal TSH). However, the new ASMs, such as levetiracetam, have no effect on thyroid hormone levels. Together, seizures not only affect thyroid hormone levels, but abnormal thyroid hormone levels can also influence seizures. However, the precise mechanism underlying the interaction between serum thyroid hormone levels and seizures remains unclear. This review aims to explore the relationship between thyroid hormone levels and seizures, along with the underlying mechanisms.

Management of Medical Complications during the Rehabilitation of Moderate-Severe Traumatic Brain Injury

According to the Centers for Disease Control, in 2019, there were approximately 223,135 hospitalizations in the United States related to traumatic brain injury (TBI). If not managed properly, these patients can suffer complications with significant negative implications with respect to morbidity, mortality, and long-term functional prognosis. It is imperative that medical providers who care for patients with TBI across the entire spectrum of care readily diagnose and treat the sequela associated with moderate-severe brain trauma. This article will focus on some of the key medical issues that providers may encounter during acute inpatient rehabilitation.

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.

Neuroprotection or Sex Bias: A Protective Response to Traumatic Brain Injury in the Females

Traumatic brain injury (TBI) is a major healthcare problem and a common cause of mortality and morbidity. Clinical and preclinical research suggests sex-related differences in short- and longterm outcomes following TBI; however, males have been the main focus of TBI research. Females show a protective response against TBI. Female animals in preclinical studies and women in clinical trials have shown comparatively better outcomes against mild, moderate, or severe TBI. This reflects a favorable protective nature of the females compared to the males, primarily attributed to various protective mechanisms that provide better prognosis and recovery in the females after TBI. Understanding the sex difference in the TBI pathophysiology and the underlying mechanisms remains an elusive goal. In this review, we provide insights into various mechanisms related to the anatomical, physiological, hormonal, enzymatic, inflammatory, oxidative, genetic, or mitochondrial basis that support the protective nature of females compared to males. Furthermore, we sought to outline the evidence of multiple biomarkers that are highly potential in the investigation of TBI's prognosis, pathophysiology, and treatment and which can serve as objective measures and novel targets for individualized therapeutic interventions in TBI treatment. Implementations from this review are important for the understanding of the effect of sex on TBI outcomes and possible mechanisms behind the favorable response in females. It also emphasizes the critical need to include females as a biological variable and in sufficient numbers in future TBI studies.

Critically ill patients: Histopathological evidence of thyroid dysfunction

PURPOSE

Critical illness is characterized by severe biphasic physical and metabolic stress as result of systemic inflammatory response syndrome and/or multiple organ dysfunction syndrome, and is frequently associated with non-thyroidal illness. Purpose of this study is to better understand the cytomorphological basis of NTI by performing histopathological examinations of thyroid gland on autopsies of patients who died from critical illness.

METHODS

Histopathological examination of thyroid gland of 58 critically ill patients was performed in our hospital. The cases included 24 cases of burn injury, 24 cases of traumatic brain injury, and 10 cases of cerebral stroke. Thyroid samples obtained during autopsy were preserved in formol saline and stained with hematoxylin and eosin. The sections were visualized under light microscopy.

RESULTS

Out of 58 cases examined, 21 patients showed normal thyroid findings, and rest of the cases had unusual thyroid findings in the histopathological study. The principal finding was distortion of thyroid follicular architecture. Other findings include mononuclear cell infiltration, clumping of thyroglobulin, and exhaustion of thyroid follicles.

CONCLUSION

Critical illness produces metabolically damaging effects on thyroid gland, which functionally corresponds to a state of low T3 syndrome. These changes are more pronounced in BI and cerebral stroke than in TBI.

Common Pathways of Epileptogenesis in Patients With Epilepsy Post-Brain Injury: Findings From a Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVES

Epilepsy may result from various brain injuries, including stroke (ischemic and hemorrhagic), traumatic brain injury, and infections. Identifying shared common biological pathways and biomarkers of the epileptogenic process initiated by the different injuries may lead to novel targets for preventing the development of epilepsy. We systematically reviewed biofluid biomarkers to test their association with the risk of post-brain injury epilepsy.

METHODS

We searched articles until January 25, 2022, in MEDLINE, Embase, PsycInfo, Web of Science, and Cochrane. The primary outcome was the difference in mean biomarker levels in patients with and without post-brain injury epilepsy. We used the modified quality score on prognostic studies for risk of bias assessment. We calculated each biomarker's pooled standardized mean difference (SMD) and 95% CI. Molecular interaction network and enrichment analyses were conducted in Cytoscape (PROSPERO CRD42021297110).

RESULTS

We included 22 studies with 1,499 cases with post-brain injury epilepsy and 7,929 controls without post-brain injury epilepsy. Forty-five biomarkers in the blood or CSF were investigated with samples collected at disparate time points. Of 22 studies, 21 had a moderate-to-high risk of bias. Most of the biomarkers (28/45) were investigated in single studies; only 9 provided validation data, and studies used variable definitions for early-onset and late-onset seizures. A meta-analysis was possible for 19 biomarkers. Blood glucose levels in 4 studies were significantly higher in patients with poststroke epilepsy (PSE) than those without PSE (SMD 0.44; CI 0.19-0.69). From individual studies, 15 biomarkers in the blood and 7 in the CSF were significantly associated with post-brain injury epilepsy. Enrichment analysis identified that the significant biomarkers (interleukin [IL]-6, IL-1β]) were predominantly inflammation related.

DISCUSSION

We cannot yet recommend using the reported biomarkers for designing antiepileptogenesis trials or use in the clinical setting because of methodological heterogeneity, bias in the included studies, and insufficient validation studies. Although our analyses indicate the plausible role of inflammation in epileptogenesis, this is likely not the only mechanism. For example, an individual's genetic susceptibilities might contribute to his/her risk of epileptogenesis after brain injury. Rigorously designed biomarker studies with methods acceptable to the regulatory bodies should be conducted.

An Approach to Traumatic Brain Injury-Related Hypopituitarism: Overcoming the Pediatric Challenges

Traumatic brain injury (TBI)-related hypopituitarism is a rare polymorphic complication of brain injury, with very little data, particularly concerning children and teenagers. This is a comprehensive review of the literature regarding this pathology, starting from a new pediatric case. The research was conducted on PubMed and included publications from the last 22 years. We identified nine original studies on the pediatric population (two case reports and seven studies; only four of these seven were prospective studies). TBI-related hypopituitarism is associated with isolated hormonal deficits ranging from 22.5% to 86% and multiple hormonal deficiencies from 5.9% to 50% in the studied pediatric population. Growth hormone (GH) deficiency is most often found, including the form with late occurrence after TBI; it was described as persistent in half of the studies. Thyroid-stimulating hormone (TSH) deficiency is identified as a distant complication following TBI; in all three studies, we identified this complication was found to be permanent. Adrenocorticotropic hormone (ACTH) deficiency did not relate to a certain type of brain trauma, and it was transient in reported cases. Hyperprolactinemia was the most frequent hormonal finding, also occurring late after injury. Central diabetes insipidus was encountered early post-TBI, typically with a transient pattern and did not relate to a particular type of injury. TBI-related hypopituitarism, although rare in children, should be taken into consideration even after a long time since the trauma. A multidisciplinary approach is needed if the patient is to safely overcome any acute condition.

Protective effects of curcumin against thyroid hormone imbalance after gas explosion-induced traumatic brain injury via activation of the hypothalamic-pituitary-thyroid axis in male rats

Gas explosion (GE)-induced traumatic brain injury (TBI) can affect thyroid hormone (TH) homeostasis in miners. This study evaluated the effects of hepatic transthyretin and hypothalamic-pituitary-thyroid (HPT) axis on thyroids and explored the protective effect and mechanism of curcumin on GE-induced TBI. Thirty rats were randomly divided into three groups (10 per group): first group (control group)-rats received GE treatment once; second group (GE group)-rats received GE treatment (200 m from the source of the explosion once); third group (GE + Cur group)-rats received curcumin (Cur) by lavage at a dose of 100 mg/kg/day once every other day for 7 days after receiving GE. After GE, the pathological changes were analyzed by hemotoxylin and eosin staining, and the levels of serum reactive oxygen species (ROS), urine iodine (UI), THs, nuclear factor-kappa B (NF-κB), superoxide dismutase (SOD), glutathione peroxidase (Gpx), and malondialdehyde (MDA) were analyzed using ELISA. Expression of proteins in the HPT axis of rats was examined by immunohistochemistry and Western blotting. We found that GE could induce pathologic changes in rat thyroid and liver. Serum levels of THs, NF-κB and serum redox state became unbalanced in rats after GE. GE could inhibit the biosynthesis and biotransformation of THs by affecting key HPT axis proteins. Additionally, GE reduced the level of hepatic transthyretin. Serum THs levels and thyroid sections were almost recovered to normal after curcumin treatment. The aforementioned key HPT axis proteins in the curcumin group showed opposite expression trends. In summary, GE affected THs balance while curcumin can protect against these injury effects by affecting TH biosynthesis, biotransformation, and transport, and inducing oxidative stress and inflammatory responses.

The Association Between FT3 With the Outcome and Inflammation/Coagulopathy/Fibrinolysis of COVID-19

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has caused substantial threats to people's physical health and lives, claiming the lives of over 5 million people worldwide. It is imperative to identify the disease severity and intervene with effective therapy as early as possible. Previous studies have shown that low free triiodothyronine (FT3) may possess the predictive value on COVID-19 prognosis.

METHODS

In this retrospective cohort study, 15-day clinical and laboratory data of 186 hospitalized patients of COVID-19 after admission were analyzed. Groups were based on the disease severity of COVID-19, survival or non-survival, and presence or absence of euthyroid sick syndrome (ESS). Categorical variables were compared with the chi-square test or Fisher's exact test. Continuous variables were tested by Wilcoxon rank-sum test for the non-normal distribution. Spearman correlations were used to assess the correlations between FT3 with clinic parameters of multiple time points.

RESULTS

The non-survival patients had significant lower levels of FT3 (3.24 ± 0.42 vs. 4.19 ± 0.08 pmol/L, p < 0.05) and thyroid-stimulating hormone (TSH) (0.69 ± 0.19 vs. 2.32 ± 0.2 uIU/ml, p < 0.05), and the FT3 of severe patients was significantly lower than that of non-severe patients (3.67 ± 0.14 vs. 4.33 ± 0.09 pmol/L, p < 0.05). Fifty-nine cases of COVID-19 patients were diagnosed with ESS. Compared with non-ESS patients, those with ESS were older and had higher proportions of fever, shortness of breath, hypertension, diabetes, severe disease, and mortality. In addition, the correlation analysis between FT3 and clinical parameters showed that FT3 were positively related to the lymphocyte count and albumin and negatively correlated with C-reactive protein, erythrocyte sedimentation rate, and D-dimer at all time points in the first 15 days after admission.

CONCLUSION

Low FT3 had a significant predictive value on the prognosis of COVID-19 patients, and FT3 was significantly related with clinic parameters of inflammation/coagulopathy/fibrinolysis.

Thyrotropic Axis and Disorders of Consciousness in Acquired Brain Injury: A Potential Intriguing Association?

PURPOSE

A potential involvement of thyrotropic axis in influencing the state of consciousness could be hypothesized. We aimed at investigating thyroid function tests as predictors of disorders of consciousness (DoC) and relating recovery in a large cohort of patients with DoC secondary to acquired brain injury (ABI).

METHODS

This retrospective, multicenter, cohort study included 151 patients with DoC following ABI, consecutively admitted for a 6-month neurorehabilitation program. Data on etiology of brain injury, evolution of DoC, disability and rehabilitation assessments, and death during rehabilitation were collected at baseline and on discharge. Thyroid function tests (serum TSH, fT4 and fT3 levels) were assessed on admission in all patients and at final discharge in 50 patients.

RESULTS

Lower baseline TSH levels and greater TSH increments (ΔTSH) after neurorehabilitation predicted a favorable change in DoC independent of age, sex, BMI, etiology of brain injury and initial DoC subtype (TSH: OR=0.712, CI 95% 0.533-0.951, p=0.01; ΔTSH: OR=2.878, CI 95% 1.147-7.223, p=0.02). On the other hand, neither fT4 nor fT3 or their variations appeared to play any role on DoC changes after 6-months inpatient neurorehabilitation. A lower magnitude of ΔfT4 acted as a strong predictor of improved functional disability level (β=0.655, p=0.002) and cognitive functions (β=-0.671, p=0.003), implying that smaller changes in fT4 were associated with higher outcomes.

CONCLUSIONS

Serum TSH levels assessed in the subacute post-ABI phase and its variation during neurorehabilitation could represent a potential biomarker of DoC evolution, while variations in fT4 levels seem to be associated with rehabilitation and cognitive functions. Further studies are needed to investigate the mechanisms underlying these associations.