A study of neuroendocrine dysfunction in patients of tuberculous meningitis

Development and validation of a new model for the early diagnosis of tuberculous meningitis in adults based on simple clinical and laboratory parameters

BACKGROUND

The differential diagnosis between tuberculous meningitis (TBM) and viral meningitis (VM) or bacterial meningitis (BM) remains challenging in clinical practice, particularly in resource-limited settings. This study aimed to establish a diagnostic model that can accurately and early distinguish TBM from both VM and BM in adults based on simple clinical and laboratory parameters.

METHODS

Patients diagnosed with TBM or non-TBM (VM or BM) between January 2012 and October 2021 were retrospectively enrolled from the General Hospital (derivation cohort) and Branch Hospital (validation cohort) of Ningxia Medical University. Demographic characteristics, clinical symptoms, concomitant diseases, and cerebrospinal fluid (CSF) parameters were collated. Univariable logistic analysis was performed in the derivation cohort to identify significant variables (P < 0.05). A multivariable logistic regression model was constructed using these variables. We verified the performance including discrimination, calibration, and applicability of the model in both derivation and validation cohorts.

RESULTS

A total of 222 patients (70 TBM and 152 non-TBM [75 BM and 77 VM]) and 100 patients (32 TBM and 68 non-TBM [31 BM and 37 VM]) were enrolled as derivation and validation cohorts, respectively. The multivariable logistic regression model showed that disturbance of consciousness for > 5 days, weight loss > 5% of the original weight within 6 months, CSF lymphocyte ratio > 50%, CSF glucose concentration < 2.2 mmol/L, and secondary cerebral infarction were independently correlated with the diagnosis of TBM (P < 0.05). The nomogram model showed excellent discrimination (area under the curve 0.959 vs. 0.962) and great calibration (P-value in the Hosmer-Lemeshow test 0.128 vs. 0.863) in both derivation and validation cohorts. Clinical decision curve analysis showed that the model had good applicability in clinical practice and may benefit the entire population.

CONCLUSIONS

This multivariable diagnostic model may help clinicians in the early discrimination of TBM from VM and BM in adults based on simple clinical and laboratory parameters.

Unusual and lesser-known rare causes of adult growth hormone deficiency

Growth hormone is among the most common hormones to be deficient in pituitary insult. It can occur either in isolation or combined with other hormone deficiencies. Growth hormone deficiency in adults (AGHD) can be due to causes acquired in adulthood or have a childhood-onset etiology, but the former is about three times more common. Usual causes of AGHD include mass effects due to a pituitary tumour, and/or its treatment (surgery, medical therapy, or radiotherapy), or radiotherapy to the head and neck region for non-pituitary lesions. The unusual or lesser-known causes of AGHD, are usually due to non-tumoral etiology and range from vascular and infective to inflammatory and miscellaneous causes. These not only expand the spectrum of AGHD but may also contribute to increased morbidity, adverse metabolic consequences, and mortality due to the primary condition, if unrecognised. The review features these lesser-known and rare causes of AGHD and highlights their clinical and diagnostic implications.

Reversible Hypothalamic Obesity in a Girl with Suprasellar Tuberculoma

INTRODUCTION

Suprasellar tuberculoma are extremely rare in children and most of those patients present with headache, vomiting, visual disturbances, and hypofunction of the pituitary gland. In this case report, we present a girl with tuberculosis, who developed significant weight gain in combination with pituitary dysfunction, which recovered after antituberculosis treatment.

CASE PRESENTATION

An 11-year old girl presented with headache, fever and anorexia that progressively evolved into an encephalopathic status with cranial nerves III and VI paresis. Brain MRI showed meningeal contrast capture along cranial nerves II (including optic chiasm), III, V and VI bilaterally and multiple contrast enhancing brain parenchyma lesions. Tuberculin skin test was negative but interferon-gamma release assay was positive. The clinical and radiological working diagnosis was consistent with tuberculous meningoencephalitis. Pulse corticosteroids for 3 days and quadruple antituberculosis therapy were started and the girl demonstrated obvious improvement of her neurological symptoms. However, after a few months of therapy she developed remarkable weight gain (+20 kg in 1 year) and growth arrest. Her hormone profile revealed insulin resistance (homeostasis model assessment-estimated insulin resistance [HOMA-IR] 6.8) despite putative growth hormone deficiency (circulating insulin-like growth factor-I [IGF-I] 104 μg/L [-2.4 SD]). Follow-up brain MRI showed a decrease in basal meningitis, but increased parenchymal lesions in the suprasellar region extending medially into the nucleus lentiformis, with now a voluminous tuberculoma at this site. Antituberculosis treatment was continued for a total of 18 months. The patient improved clinically, she regained her pre-illness Body Mass Index (BMI) SDS and her growth rate increased slightly. On the hormonal side, disappearance of insulin resistance (HOMA-IR 2.5) and an increase in IGF-I (175 μg/L, -1.4 SD) was noted, and her last brain MRI showed a remarkable volume reduction of the suprasellar tuberculoma.

CONCLUSION

Suprasellar tuberculoma can have a very dynamic presentation during the active stage of the disease, which can be reversed by prolonged antituberculosis treatment. Previous studies showed that the tuberculous process can also cause long term and irreversible changes in the hypothalamic-pituitary axis. Prospective studies are however needed in the pediatric population to know the exact incidence and type of pituitary dysfunction.

Approach to a case with an unusual cause of hypopituitarism

Hypopituitarism refers to insufficiency of one or more hormones of the pituitary and can be due to myriad causes. The clinical and radiological spectrum of the condition is heterogeneous, based on the age, gender, clinical setting and/or other past medical history. Hypopituitarism includes central hypocortisolism, hypothyroidism, hypogonadism and growth hormone deficiency. Both hypo- and hyperprolactinemia can be associated with hypopituitarism, with low prolactin signifying more extensive pituitary damage. Posterior pituitary insufficiency (arginine vasopressin deficiency), occurs either in isolation or with anterior pituitary hormone deficiency. Clinical symptomatology of hypopituitarism is usually non-specific and insidious in onset and progression. Overall, the most common cause of hypopituitarism is a pituitary adenoma and/or its management (surgery, radiotherapy, pharmacotherapy or a combination of these). However, it is this subset of patients which is more likely to be identified and managed timely, possibly alleviating the premature mortality associated with hypopituitarism. What is more challenging is the recognition of hypopituitarism in less common settings, which may be either due to direct involvement of the pituitary (infection, traumatic brain injury, or infiltrative causes) or indirectly as a consequence of the primary process (thalassemia, vasculotoxic snakebite, subarachnoid hemorrhage). These entities are often under-recognised, and increased awareness can help in greater recognition of the problem burden. Further, pituitary insufficiency in most of these settings is dynamic, which may progress, or rarely, show recovery of function. This renders complexity to the problem, but makes it even more imperative to suspect, screen and appropriately manage patients with less common causes of hypopituitarism.

Associations of hyponatremia and SIADH with increased mortality, young age and infection parameters in patients with tuberculosis

BACKGROUND AND OBJECTIVE

Hyponatremia and the syndrome of inappropriate antidiuretic hormone secretion (SIADH) are associated with and can be caused by tuberculosis (TB) through meningitis by locally invading the hypothalamus, adrenal, or pituitary glands or possibly through ectopic ADH production. This study assessed the association of TB mortality with hyponatremia and SIADH in a large cohort of a university hospital in Austria.

METHODS

This retrospective study enrolled patients with hyponatremia and patients diagnosed with TB from 01/2001-11/2019 to assess the prevalence of TB in hyponatremia and TB morbidity and mortality in patients with and without hyponatremia. Sex, age, microbiological results, laboratory tests and comorbidities were analysed and used to calculate survival rates.

RESULTS

Of 107.532 patients with hyponatremia (0.07%) and 186 patients with TB (43%), 80 patients were diagnosed with both-hyponatremia and TB. Only three TB patients had SIADH, precluding further SIADH analysis. In hyponatremia, young age and high CRP levels showed significant associations with TB diagnosis (p<0.0001). Survival rates of patients diagnosed with TB with moderate to profound hyponatremia were significantly lower than those without hyponatremia (p = 0.002).

CONCLUSION

In this study of a large cohort from a tertiary care hospital in a non-endemic area of TB, 0.07% of patients presenting with hyponatremia, but especially younger patients and patients with high CRP values, were diagnosed with TB. Crucially, patients with moderate to profound hyponatremia had a significantly higher mortality rate and thus required increased medical care.

Global Frequency and Clinical Features of Stroke in Patients With Tuberculous Meningitis: A Systematic Review

IMPORTANCE

Stroke in tuberculous meningitis (TBM) is associated with significant morbidity and mortality.

OBJECTIVE

To determine the country-specific, regional, and overall prevalence of stroke among patients with TBM, including their clinical manifestations, stroke locations, and outcomes.

EVIDENCE REVIEW

This systematic review searched records in MEDLINE by PubMed, Scopus, and EMBASE until July 2020 for relevant articles on the occurrence and characteristics of stroke in TBM. Randomized clinical trials and cohort studies that included a population of patients with TBM were analyzed for clinical manifestations, type of stroke, area of stroke, vascular territory, and outcomes. Studies that did not report the occurrence of stroke, reported as abstract only with no full-texts available, and articles not in English were excluded. The country-specific, regional, and overall frequencies of stroke among patients with TBM were determined; secondary analysis enumerated the summary estimates of the clinical presentations, common locations of stroke, and outcomes. The Murad tool was used to assess methodological quality.

FINDINGS

From 852 articles identified, 71 studies involving 2194 patients with stroke in TBM were included. The sample size for each study ranged from 17 to 806 patients. The frequency of stroke in TBM showed an estimate of 0.30 (95% CI, 0.26-0.33). The most common clinical manifestations were fever and headache. The lateral striate, middle cerebral, and medial striate arteries were typically affected. The basal ganglia, cortex and lobar, and internal capsule were the frequently involved areas of the brain. The pooled proportions of mortality and poor outcomes were 0.22 (95% CI, 0.16-0.29) and 0.51 (95% CI, 0.37-0.66), respectively.

CONCLUSIONS AND RELEVANCE

The results of this systematic review suggest that stroke is considerably frequent among patients with TBM. The reported frequencies of stroke in TBM and its clinical features vary across the studies and populations.

Mechanism, spectrum, consequences and management of hyponatremia in tuberculous meningitis

Hyponatremia is the commonest electrolyte abnormality in hospitalized patients and is associated with poor outcome. Hyponatremia is categorized on the basis of serum sodium into severe (< 120 mEq/L), moderate (120-129 mEq/L) and mild (130-134mEq/L) groups. Serum sodium has an important role in maintaining serum osmolality, which is maintained by the action of antidiuretic hormone (ADH) secreted from the posterior pituitary, and natriuretic peptides such as atrial natriuretic peptide and brain natriuretic peptide. These peptides act on kidney tubules via the renin angiotensin aldosterone system. Hyponatremia <120mEq/L or a rapid decline in serum sodium can result in neurological manifestations, ranging from confusion to coma and seizure. Cerebral salt wasting (CSW) and syndrome of inappropriate secretion of ADH (SIADH) are important causes of hyponatremia in tuberculosis meningitis (TBM). CSW is more common than SIADH. The differentiation between CSW and SIADH is important because treatment of one may be detrimental for the other; evidence of hypovolemia in CSW and euvolemia or hypervolemia in SIADH is used for differentiation. In addition, evidence of dehydration, polyuria, negative fluid balance as assessed by intake output chart, weight loss, laboratory evidence and sometimes central venous pressure are helpful in the diagnosis of these disorders. Volume contraction in CSW may be more protracted than hyponatremia and may contribute to border zone infarctions in TBM. Hyponatremia should be promptly and carefully treated by saline and oral salt, while 3% saline should be used in severe hyponatremia with coma and seizure. In refractory patients with hyponatremia, fludrocortisone helps in early normalization of serum sodium without affecting polyuria or functional outcome. In SIADH, V2 receptor antagonist conivaptan or tolvaptan may be used if the patient is not responding to fluid restriction. Fluid restriction in SIADH has not been found to be beneficial in TBM and should be avoided.

Mechanism, spectrum, consequences and management of hyponatremia in tuberculous meningitis

Hyponatremia is the commonest electrolyte abnormality in hospitalized patients and is associated with poor outcome. Hyponatremia is categorized on the basis of serum sodium into severe (< 120 mEq/L), moderate (120-129 mEq/L) and mild (130-134mEq/L) groups. Serum sodium has an important role in maintaining serum osmolality, which is maintained by the action of antidiuretic hormone (ADH) secreted from the posterior pituitary, and natriuretic peptides such as atrial natriuretic peptide and brain natriuretic peptide. These peptides act on kidney tubules via the renin angiotensin aldosterone system. Hyponatremia <120mEq/L or a rapid decline in serum sodium can result in neurological manifestations, ranging from confusion to coma and seizure. Cerebral salt wasting (CSW) and syndrome of inappropriate secretion of ADH (SIADH) are important causes of hyponatremia in tuberculosis meningitis (TBM). CSW is more common than SIADH. The differentiation between CSW and SIADH is important because treatment of one may be detrimental for the other; evidence of hypovolemia in CSW and euvolemia or hypervolemia in SIADH is used for differentiation. In addition, evidence of dehydration, polyuria, negative fluid balance as assessed by intake output chart, weight loss, laboratory evidence and sometimes central venous pressure are helpful in the diagnosis of these disorders. Volume contraction in CSW may be more protracted than hyponatremia and may contribute to border zone infarctions in TBM. Hyponatremia should be promptly and carefully treated by saline and oral salt, while 3% saline should be used in severe hyponatremia with coma and seizure. In refractory patients with hyponatremia, fludrocortisone helps in early normalization of serum sodium without affecting polyuria or functional outcome. In SIADH, V2 receptor antagonist conivaptan or tolvaptan may be used if the patient is not responding to fluid restriction. Fluid restriction in SIADH has not been found to be beneficial in TBM and should be avoided.

The pathogenesis of tuberculous meningitis

Tuberculosis (TB) remains a leading cause of death globally. Dissemination of TB to the brain results in the most severe form of extrapulmonary TB, tuberculous meningitis (TBM), which represents a medical emergency associated with high rates of mortality and disability. Via various mechanisms the Mycobacterium tuberculosis (M.tb) bacillus disseminates from the primary site of infection and overcomes protective barriers to enter the CNS. There it induces an inflammatory response involving both the peripheral and resident immune cells, which initiates a cascade of pathologic mechanisms that may either contain the disease or result in significant brain injury. Here we review the steps from primary infection to cerebral disease, factors that contribute to the virulence of the organism and the vulnerability of the host and discuss the immune response and the clinical manifestations arising. Priorities for future research directions are suggested.