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

Seizures and epilepsy associated with central nervous system tuberculosis

Central nervous system (CNS) tuberculosis is a life-threatening condition that usually presents with seizures, particularly in children and HIV-infected patients. Tuberculous meningitis (TBM) and tuberculomas are the two forms of CNS tuberculosis that can present with seizures. Seizures usually resolve after successful treatment of the underlying infection. However, the success of the treatment is usually based on an early diagnosis. Delay in the treatment of CNS tuberculosis increases the risk of its associated complications, such as stroke. This would lead to the development of epilepsy. Early seizures may be related to meningeal irritation and cerebral edema, whereas late seizures are often associated with structural brain lesions that generally require more advanced and prolonged treatment. Risk factors associated with the development of epilepsy include young age, refractory seizures, tuberculoma, cortical involvement, epileptiform discharges, and residual lesions. Treatment of CNS tuberculosis is based on early initiation of appropriate anti-tuberculous drugs, antiseizure medications, and correction of associated predisposing factors. Finally, further research into the mechanisms of seizures and the development of epilepsy in CNS tuberculosis could help improve management of these conditions.

Impact of surgical factors on delayed hyponatremia in patients with nonfunctioning pituitary adenoma after endonasal endoscopic transsphenoidal procedure

PURPOSE

Delayed hyponatremia can occur after pituitary surgery, resulting in prolonged hospitalization. However, the influence of surgical factors after such a procedure has not been well established. The impact of surgery and related factors on delayed hyponatremia was investigated.

METHODS

This was a retrospective analysis of 137 consecutive patients who underwent transsphenoidal surgery for a nonfunctioning pituitary adenoma between 2008 and 2019. Preoperative (demographics, comorbidities), intraoperative (resection extent, operation time, blood loss volume, cerebrospinal fluid leak, tumor consistency), and postoperative [hematoma, meningitis, diabetes insipidus (DI), hormonal assessment] data were collected, with statistical analysis of each factor performed.

RESULTS

Among the 137 patients, delayed hyponatremia occurred in 31 (22.6%). Multivariate analysis revealed that those with hypertension had a significantly higher likelihood of avoiding delayed hyponatremia (p = 0.004). Although no correlations of direct surgical factors with delayed hyponatremia were found, multivariate analysis of indirect surgical factors showed that presence of a firm tumor, transient DI, and meningitis were significantly associated with delayed hyponatremia (p = 0.014, 0.001, and 0.047, respectively). There was also a significant association of severe hyponatremia with appearance of symptoms (p = 0.002).

CONCLUSION

There was a tendency for hypertension to be associated with delayed hyponatremia avoidance, with indirect surgical factors including tumor consistency, transient DI, and meningitis found to have an influence on delayed hyponatremia. It was concluded that attention should be given to non-hypertensive patients with a firm tumor, transient DI, or meningitis after pituitary surgery, as delayed hyponatremia may occur.

Stroke in Tuberculous Meningitis and Its correlation with Magnetic Resonance Angiography Manifestations

Objective  The primary objective of the study was to assess the location of cerebral infarction and look for corresponding magnetic resonance angiography (MRA) changes in patients with tuberculous meningitis (TBM). We also evaluated the predictors of ischemic stroke in TBM and the impact of these infarctions on patient's outcome.

Methods  This was a single-center prospective study between September 2018 and September 2020. Demographic and laboratory parameters were noted. Cranial magnetic resonance imaging and MRA were performed at the time of admission to the hospital.

Results  Among 120 patients with TBM, 46 had stroke. Nineteen (15.8%) patients died, of which 12 (10%) suffered from stroke. The most common site of infarction was the basal ganglia (54.3%). The commonest site of MRA abnormalities was the middle cerebral artery (39.1%). British Medical Research Council (BMRC) stage 3, cerebrospinal fluid (CSF) sugar, CSF adenosine deaminase (ADA) level, basal exudates, hydrocephalus, and hyponatremia were found to be predictors of stroke in TBM, while BMRC stage 3, CSF cell count, CSF ADA level, and anemia were found to be significantly associated with mortality in TBM patients with stroke.

Conclusion  The basal ganglia were the most common site of ischemic stroke in TBM, and middle cerebral artery was the most often involved intracranial blood vessel. BMRC stage 3 was significantly associated with both stroke and mortality in TBM patients with stroke.

First Reported Case of Reverse Pott’s Disease

Tuberculosis, while rare, is a disease that can have several extrapulmonary manifestations. One such known extrapulmonary manifestation of disseminated TB is vertebral osteomyelitis, often referred to as “Pott’s Disease.” We present the case of a patient who underwent back surgery with allogenic bone graft who developed vertebral osteomyelitis and subsequently had disseminated tuberculosis, from an infected bone graft. We review current guidelines for allograft tissue screening and discuss the possible need for standardizing tuberculosis screening for bone allografts.

The Impact of Hyponatremia on the Severity of Childhood Tuberculous Meningitis

Introduction: Hyponatremia and/or hypoglycorrhachia are commonly encountered biochemical derangements during the acute stage of childhood tuberculous meningitis (TBM). Few studies have explored the correlation between these derangements and the staging of TBM disease (severity), or explored their role as biomarkers for vascular ischemic events, hydrocephalus, or seizures. Methods: We aimed to identify the prevalence and the correlation between serum hyponatremia (mild, moderate and severe) and/or hypoglycorrhachia in relation to clinical TBM features such as stage of disease, seizures and stroke in children diagnosed with definite and probable TBM, between 1985 and 2015, at Tygerberg Hospital, Cape town, South Africa. Results: The prevalence of hyponatremia was 344 out of 481 (71.5%) patients; 169 (49.1%) had mild hyponatremia, 146 (42.4%) moderate hyponatremia and 29 (8.4%) severe hyponatremia. Children with severe hyponatremia had higher frequency of stroke [odds ratio (OR) 4.36, 95% confidence interval (CI) 1.24-15.35; p = 0.01], brainstem dysfunction (OR 7.37, 95% CI 2.92-18.61; p < 0.01), cranial nerve palsies (OR 2.48, 95% CI 1.04-5.91; p = 0.04) and non-communicating hydrocephalus (OR 2.66, 95% CI 1.09-6.44; p = 0.03). Children with moderate hyponatremia and mild hyponatremia compared to those without hyponatremia similarly were more likely to exhibit signs of brainstem dysfunction (OR 1.91, 95% CI 1.11-3.28; p = 0.02) and hydrocephalus (OR 3.18, 95% CI 1.25-8.09; p = 0.01), respectively. On multivariable analysis only brainstem dysfunction was significantly associated with severe hyponatremia [adjusted odds ratio (aOR) 4.46, 95% CI 1.62-12.30; p < 0.01]. Children with hypoglycorrhachia compared to normoglycorrhachia were more likely to have had longer symptom duration prior to admission (OR 1.87, 95% CI 1.09-3.20; p = 0.02), non-communicating hydrocephalus (OR 1.64, 95% CI 0.99-2.71; p = 0.05), higher cerebrospinal white cell counts (OR 3.00, 95% CI 1.47-6.12; p < 0.01) and higher CSF protein concentrations (OR 2.51, 95% CI 1.49-4.20; p < 0.01). On multivariable analysis raised CSF protein concentration >1 g/L was significantly associated with hypoglycorrhachia (aOR 2.52, 95% CI 1.44-4.40; p < 0.01). Death rates did not differ by sodium level category or presence of hypoglycorrachia, however an increasing trend of children that had demised was noted the more severe the sodium category. Conclusion: Hyponatremia and/or hypoglycorrhachia occur in more than two-thirds of children with TBM. Severe TBM disease complications such as brainstem dysfunction was associated with moderate hyponatremia, while severe hyponatremia was associated with brainstem dysfunction, stroke, cranial nerve palsies and non-communicating hydrocephalus. Cerebrospinal fluid (CSF) glucose depletion correlated with non-communicating hydrocephalus and increased CSF inflammation.

CSF Metabolomics of Tuberculous Meningitis: A Review

From the World Health Organization's global TB report for 2020, it is estimated that in 2019 at least 80,000 children (a particularly vulnerable population) developed tuberculous meningitis (TBM)-an invariably fatal disease if untreated-although this is likely an underestimate. As our latest technologies have evolved-with the unprecedented development of the various "omics" disciplines-a mountain of new data on infectious diseases have been created. However, our knowledge and understanding of infectious diseases are still trying to keep pace. Metabolites offer much biological information, but the insights they permit can be difficult to derive. This review summarizes current metabolomics studies on cerebrospinal fluid (CSF) from TBM cases and collates the metabolic data reported. Collectively, CSF metabolomics studies have identified five classes of metabolites that characterize TBM: amino acids, organic acids, nucleotides, carbohydrates, and "other". Taken holistically, the information given in this review serves to promote the mechanistic action of hypothesis generation that will drive and direct future studies on TBM.

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.

Central nervous system tuberculosis

PURPOSE OF REVIEW

Central nervous system (CNS) tuberculosis is the most devastating form of tuberculosis (TB), with mortality and or neurological sequelae in over half of individuals. We reviewed original research and systematic reviews published since 1 January 2019 for new developments in CNS TB pathophysiology, diagnosis, management and prognosis.

RECENT FINDINGS

Insight in the pathophysiology is increasing steadily since the landmark studies in 1933, focussing on granuloma type classification, the relevance of the M. tuberculosis bacterial burden and the wide range of immunological responses. Although Xpert/RIF has been recommended by the WHO for extrapulmonary TB diagnosis, culture is still needed to increase the sensitivity of TB meningitis diagnosis. Sequential MRIs can improve understanding of neurological deficits at baseline and during treatment. Pharmacokinetic/pharmacodynamic modelling suggests that higher doses of rifampicin and isoniazid in TB meningitis could improve survival.

SUMMARY

Recent studies in the field of CNS-TB have largely focussed on TB meningitis. The outcome may improve by optimizing treatment dosing. This needs to be confirmed in clinical trials. Due to the important role of inflammation, these trials should be used as the platform to study the inflammatory and metabolomic responses. This could improve understanding of the biology of this disease and improve patient outlook by enabling individualised host-directed therapy.

The association between serum sodium level and tuberculous meningitis compared with viral and bacterial meningitis

We evaluated the association between hyponatremia and tuberculous meningitis (TBM) with the aim of providing additional information for differential diagnosis from other types of infectious meningitis, especially viral meningitis (VM). Cross-sectional and longitudinal data involving 5026 participants older than 18 years were analyzed in the total population and a propensity-matched population. The initial and lowest sodium levels and longitudinal changes in TBM, bacterial meningitis (BM), and VM patients were compared. Participants in the TBM group were enrolled when they were diagnosed as possible, probable, or definite TBM according to the Marais' criteria. The initial serum sodium level was significantly lower in TBM patients than in BM and VM patients (136.9 ± 5.9 vs. 138.3 ± 4.7 mmol/L, p < 0.001 for TBM vs. BM, and 139.0 ± 3.1, p < 0.001 for TBM vs. VM), and it decreased significantly more steeply to lower levels in both the TBM and BM patients compared with VM patients. The lowest serum sodium level was in the order of TBM < BM < VM patients, and the change was statistically significant in all subgroups (131.8 ± 6.4, 133.1 ± 5.1, 137.4 ± 3.7, respectively, p < 0.001). Participants with lower serum sodium level were more likely to have a diagnosis of TBM rather than VM, and this association was more pronounced for the lowest sodium level than the initial sodium level [OR 4.6 (95% CI 2.4-8.8, p < 0.001)]. These findings indicate that baseline and longitudinal evaluation of serum sodium level can provide information for differential diagnosis of TBM from BM or VM.