Cognitive Impairment in Tuberculous Meningitis

Tuberculous meningitis as an underlying cause of rapid neurological deterioration in a patient with a history of psychiatric disorder: Clinical case report

Tuberculous meningitis (TBM), the least common of extrapulmonary tuberculosis presentations, one of the most severe. Highly prevalent in immunosuppressed individuals it is associated with high mortality and significant neurological sequelae. TBM main complications are hydrocephalus, increased intracranial pressure, and compromised blood flow with poor prognosis. The diagnostic approach is complex, as the manifestations of TBM are nonspecific. In the case reported here, the first symptoms of TBM were masked by clinical manifestations of depressive syndrome (previously diagnosed) and its management with antidepressants. The confirmatory diagnosis was based on GenXpert on cerebrospinal fluid and neuroimaging, as in our case, tools frequently delayed. The patient presented sudden neurological deterioration, probably due to dysregulation of the immune system associated with depression and smoking habits. In areas with a high incidence of TB, neurological manifestations, even in patients with psychiatric disorders, should be considered as a differential diagnosis or infectious comorbidity such as TBM.

Cognitive performance, neuropsychiatric symptoms, and cerebrospinal fluid viral control following programmatic switch from efavirenz-based to dolutegravir-based antiretroviral therapy in South Africa (CONNECT): a prospective cohort study

BACKGROUND

Both efavirenz and dolutegravir have been associated with neuropsychiatric side-effects and cognitive impairment. Furthermore, cerebrospinal fluid (CSF) HIV RNA escape has not been comprehensively studied in African populations. We aimed to examine changes in cognition, neuropsychiatric symptoms, and CSF viral control associated with the widespread switch from efavirenz-based to dolutegravir-based antiretroviral therapy (ART).

METHODS

This prospective cohort study of people with HIV and people without HIV recruited adults with HIV (aged 18-55 years) from the Gugulethu Community Health Centre in a low-income periurban area of Cape Town, South Africa. Eligible participants had been receiving efavirenz-based ART for at least 1 year and were identified by the clinic to switch to dolutegravir-based ART as part of the national programmatic switch. Participants were studied at baseline and followed up at 1 year after switch to dolutegravir. People without HIV were recruited from the same area, matched for age and gender, and followed up at the same time interval. People with HIV and people without HIV underwent comprehensive cognitive testing over seven domains and measures of functioning, mood, anxiety, and sleep. People with HIV had CSF sampling for HIV RNA quantification.

FINDINGS

Between Aug 12, 2019, and Sept 16, 2022, we recruited 178 people with HIV and 95 people without HIV. 145 (81%) of 178 people with HIV and 40 (66%) of 60 people without HIV who were offered underwent follow-up. Global cognitive performance was 2·57 T score points lower in people with HIV than in people without HIV at baseline (p=0·0008). At follow-up, cognition in people with HIV improved more than practice effects observed in people without HIV (coefficient 1·40, 95% CI 0·48-2·32, p=0·0028) and no significant difference in cognitive performance between groups was apparent (51·43 vs 52·73; p=0·22). Sleep quality improved following the switch (risk ratio 0·90, 95% CI 0·84-0·95; p=0·0002), driven mainly by indicators of disturbed sleep. There were nine incident cases of depression, although baseline differences were present. There was one case (1%) of CSF escape at baseline and three cases (4%) at follow-up; all were at low levels or resolved with repeated sampling.

INTERPRETATION

Improvements in cognition and sleep are probably related to switching from efavirenz. However, the possible increase in depression warrants further examination. Cognitive performance in virally supressed African people with HIV receiving dolutegravir-based therapy is similar to people without HIV. CSF escape is uncommon on both efavirenz-based and dolutegravir-based therapy.

FUNDING

South African Medical Research Council and UK Medical Research Council, Newton Fund.

Extracorporeal membrane oxygenation in acute respiratory distress syndrome caused by elderly tuberculous meningitis: a case report and review of the literature

Diagnosing and clinical management of tuberculous meningitis (TBM) are still challenging for clinicians. Analysis of cerebrospinal fluid (CSF) is an important diagnostic tool for patients with suspected central nervous system (CNS) diseases. Acute respiratory distress syndrome (ARDS), an inflammatory lung injury, can be treated by mechanical ventilation, fluid management, and even extracorporeal membrane oxygenation (ECMO). In addition, metagenomic next-generation sequencing (mNGS) can facilitate the detection of atypical, rare pathogens in clinical specimens. We report a case of a 65-year-old man with ARDS caused by TBM. He was admitted with a fever and shaking. Despite aggressive initial treatment, the patient progressed rapidly and developed ARDS. Without positive results of mNGS and culture, anti-tuberculosis (TB) treatment was started. In order to improve oxygenation levels, he was placed on veno-venous ECMO for 8 days. On day 47, the tracheotomy catheter was pulled out and sealed. The patient was conscious and could communicate with family members as normal.

Acute infections of the central nervous system in children and adults: diagnosis and management

Central nervous system infections are due to different microorganisms such as viruses, bacteria, mycobacteria, fungi, amoebas, and other parasites. The etiology depends on multiple risk factors, and it defines the infection location because some microorganisms prefer meninges, brain tissue, cerebellum, brain stem or spinal cord. The microorganisms induce diseases in the nervous system through direct invasion, neurotoxin production, and the triggered immune response. To determine the infection etiology, there are several diagnostic tests which may be conducted with cerebrospinal fluid, blood, respiratory and stool samples. These tests include but are not limited to direct microscopic examination of the sample, stains, cultures, antigenic tests, nucleic acid amplification tests, metagenomic next-generation sequencing, immunologic biomarker and neuroimaging, especially contrast-enhanced magnetic resonance imaging. The treatment may consist of specific antimicrobial treatment and supportive standard care. Since viruses have no specific antiviral treatment, antimicrobial treatment is mainly targeted at non-viral infections. This article will focus on diagnosis and treatment of acute acquired infections of the central nervous system beyond the neonatal period. The discussion defines the disease, provides the clinical presentation, explains the etiology and risk factors, and briefly mentions potential complications. This updated review aims to provide the reader with all the elements needed to adequately approach a patient with a central nervous system infection. Mycobacterium tuberculosis infection, Cryptococcus spp. infection and vaccines are not within the scope of this article.

Potential of Neuroinflammation-Modulating Strategies in Tuberculous Meningitis: Targeting Microglia

Tuberculous meningitis (TBM) is the most severe complication of tuberculosis (TB) and is associated with high rates of disability and mortality. Mycobacterium tuberculosis (M. tb), the infectious agent of TB, disseminates from the respiratory epithelium, breaks through the blood-brain barrier, and establishes a primary infection in the meninges. Microglia are the core of the immune network in the central nervous system (CNS) and interact with glial cells and neurons to fight against harmful pathogens and maintain homeostasis in the brain through pleiotropic functions. However, M. tb directly infects microglia and resides in them as the primary host for bacillus infections. Largely, microglial activation slows disease progression. The non-productive inflammatory response that initiates the secretion of pro-inflammatory cytokines and chemokines may be neurotoxic and aggravate tissue injuries based on damages caused by M. tb. Host-directed therapy (HDT) is an emerging strategy for modulating host immune responses against diverse diseases. Recent studies have shown that HDT can control neuroinflammation in TBM and act as an adjunct therapy to antibiotic treatment. In this review, we discuss the diverse roles of microglia in TBM and potential host-directed TB therapies that target microglia to treat TBM. We also discuss the limitations of applying each HDT and suggest a course of action for the near future.

Acute ischemic stroke in tuberculous meningitis

Background

The underlying mechanism for stroke in patients with tuberculous meningitis (TBM) remains unclear. This study aimed to investigate the predictors of acute ischemic stroke (AIS) in TBM and whether AIS mediates the relationship between inflammation markers and functional disability.

Methods

TBM patients admitted to five hospitals between January 2011 and December 2021 were consecutively observed. Generalized linear mixed model and subgroup analyses were performed to investigate predictors of AIS in patients with and without vascular risk factors (VAFs). Mediation analyses were performed to explore the potential causal chain in which AIS may mediate the relationship between neuroimaging markers of inflammation and 90-day functional outcomes.

Results

A total of 1,353 patients with TBM were included. The percentage rate of AIS within 30 days after admission was 20.4 (95% CI, 18.2-22.6). A multivariate analysis suggested that age ≥35 years (OR = 1.49; 95% CI, 1.06-2.09; P = 0.019), hypertension (OR = 3.56; 95% CI, 2.42-5.24; P < 0.001), diabetes (OR = 1.78; 95% CI, 1.11-2.86; P = 0.016), smoking (OR = 2.88; 95% CI, 1.68-4.95; P < 0.001), definite TBM (OR = 0.19; 95% CI, 0.06-0.42; P < 0.001), disease severity (OR = 2.11; 95% CI, 1.50-2.90; P = 0.056), meningeal enhancement (OR = 1.66; 95% CI, 1.19-2.31; P = 0.002), and hydrocephalus (OR = 2.98; 95% CI, 1.98-4.49; P < 0.001) were associated with AIS. Subgroup analyses indicated that disease severity (P for interaction = 0.003), tuberculoma (P for interaction = 0.008), and meningeal enhancement (P for interaction < 0.001) were significantly different in patients with and without VAFs. Mediation analyses revealed that the proportion of the association between neuroimaging markers of inflammation and functional disability mediated by AIS was 16.98% (95% CI, 7.82-35.12) for meningeal enhancement and 3.39% (95% CI, 1.22-6.91) for hydrocephalus.

Conclusion

Neuroimaging markers of inflammation were predictors of AIS in TBM patients. AIS mediates < 20% of the association between inflammation and the functional outcome at 90 days. More attention should be paid to clinical therapies targeting inflammation and hydrocephalus to directly improve functional outcomes.

Interactions between CNS and immune cells in tuberculous meningitis

The central nervous system (CNS) harbors its own special immune system composed of microglia in the parenchyma, CNS-associated macrophages (CAMs), dendritic cells, monocytes, and the barrier systems within the brain. Recently, advances in the immune cells in the CNS provided new insights to understand the development of tuberculous meningitis (TBM), which is the predominant form of Mycobacterium tuberculosis (M.tb) infection in the CNS and accompanied with high mortality and disability. The development of the CNS requires the protection of immune cells, including macrophages and microglia, during embryogenesis to ensure the accurate development of the CNS and immune response following pathogenic invasion. In this review, we summarize the current understanding on the CNS immune cells during the initiation and development of the TBM. We also explore the interactions of immune cells with the CNS in TBM. In the future, the combination of modern techniques should be applied to explore the role of immune cells of CNS in TBM.

A preclinical model of TB meningitis to determine drug penetration and activity at the sites of disease

Tuberculosis meningitis (TBM) is essentially treated with the first-line regimen used against pulmonary tuberculosis, with a prolonged continuation phase. However, clinical outcomes are poor in comparison, for reasons that are only partially understood, highlighting the need for improved preclinical tools to measure drug distribution and activity at the site of disease. A predictive animal model of TBM would also be of great value to prioritize promising drug regimens to be tested in clinical trials, given the healthy state of the development pipeline for the first time in decades. Here, we report the optimization of a rabbit model of TBM disease induced via inoculation of Mycobacterium tuberculosis into the cisterna magna, recapitulating features typical of clinical TBM: neurological deterioration within months post-infection, acid-fast bacilli in necrotic lesions in the brain and spinal cord, and elevated lactate levels in cerebrospinal fluid (CSF). None of the infected rabbits recovered or controlled the disease. We used young adult rabbits, the size of which allows for spatial drug quantitation in critical compartments of the central nervous system that cannot be collected in clinical studies. To illustrate the translational value of the model, we report the penetration of linezolid from plasma into the CSF, meninges, anatomically distinct brain areas, cervical spine, and lumbar spine. Across animals, we measured the bacterial burden concomitant with neurological deterioration, offering a useful readout for drug efficacy studies. The model thus forms the basis for building a preclinical platform to identify improved regimens and inform clinical trial design.

Validation of a quantitative liquid chromatography tandem mass spectrometry assay for linezolid in cerebrospinal fluid and its application to patients with HIV-associated TB-meningitis

Tuberculous meningitis treatment outcomes are poor and alternative regimens are under investigation. Reliable methods to measure drug concentrations in cerebrospinal fluid are required to evaluate distribution into the cerebrospinal fluid. A simple and quick method was developed and validated to analyse linezolid in human cerebrospinal fluid. Samples were prepared by protein precipitation followed by isocratic liquid chromatography and tandem mass spectrometry. The run time was 3.5 min. Accuracy and precision were assessed in three independent validation batches with a calibration range of 0.100-20.0 μg/mL. The method was used to analyse cerebrospinal fluid samples from patients with tuberculous meningitis enrolled in a clinical trial. Potentially infective patient samples could be decontaminated using Nanosep® nylon and Costar® nylon filter tubes under biosafety level 3 conditions before analysis. The filtration process did not significantly affect the quantification of linezolid. Linezolid concentration in cerebrospinal fluid obtained from tuberculous meningitis patients ranged from 0.197 μg/mL to 15.0 μg/mL. The ratio between average CSF and plasma linezolid concentrations varied with time, reaching a maximum of 0.9 at 6 h after dosing.