Phenotypic interaction of simultaneously administered isoniazid and phenytoin in patients with tuberculous meningitis or tuberculoma having seizures

Reasons for re-hospitalization in patients with tuberculous meningitis, and its impact on outcome: a prospective observational study

BACKGROUND

Patients with tuberculous meningitis may worsen despite being treated adequately with anti-tuberculosis drugs. This worsening may lead to re-hospitalization. The exact frequency and causes of re-hospitalization have not been studied previously. We aimed to study the causes of clinical worsening leading to re-hospitalization and its impact on prognosis.

METHODS

This was a prospective observational study. Newly diagnosed patients with tuberculous meningitis (N = 150) were enrolled. Baseline clinical evaluation, neuroimaging, and cerebrospinal fluid examination were performed. Anti-tuberculosis drug regimen and corticosteroids were given as per WHO guidelines. Patients were followed for 6 months. Re-hospitalized patients were worked up and clinical evaluation, neuroimaging, and cerebrospinal fluid examination were performed again. Outcome assessment was done at the end of 6 months, and a modified Barthel index of ≤ 12 was considered a poor outcome.

RESULTS

Twenty-three (15.3%) out of 150 patients needed re-hospitalization. The median time between discharge after the first hospitalization and re-hospitalization was 60 days. The common reasons for re-hospitalization were paradoxical neurological deterioration seen in 19 (82.6%) out of 23 patients, followed by drug toxicities (N = 2) and systemic involvement (N = 2). Paradoxically developed spinal arachnoiditis and opto-chiasmatic arachnoiditis were amongst the predominant reasons for re-hospitalization. At six months, re-hospitalization was an independent predictor of poor outcome (OR = 7.39, 95% CI 2.26-24.19).

CONCLUSION

Approximately 15% of tuberculous meningitis patients needed re-hospitalization. Paradoxically developed spinal arachnoiditis and opto-chiasmatic arachnoiditis were predominant reasons for re-hospitalization. Re-hospitalization adversely affected the outcome.

Additional considerations for "checklists to guide the supportive and critical care of tuberculous meningitis"

Checklists are pivotal in the systematic assessment of critically ill patients, pre-operative assessments and for patients with multisystem involvements. Management of tuberculous meningitis is challenging due to prolonged hospital stay, multiple neurological complications like seizures, stroke, raised intracranial tension, stroke, neurosurgical interventions, multiple invasive procedures, health-care-associated sepsis, and ventilation. All these complications are managed by separate checklists to avoid treatment-related errors. The current manuscript aims to ensure completeness of inpatient care addressing issues addressing diagnostic issues, supportive care, and intensive care related issues.

The prevalence, characteristics and outcome of seizure in tuberculous meningitis

Seizures are a common finding in patients with tuberculous meningitis (TBM), and associate with four times increased risk of death and neurological disability, especially in children. It has been reported that brain inflammation, diffuse neuronal injury, and reactive gliosis may all contribute to the pathogenesis of seizures in TBM. Early seizure onset may be associated with meningeal irritation and cerebral oedema; while, the late seizures are usually due to infarction, hydrocephalus, tuberculoma and paradoxical response. Moreover, recurrent uncontrolled seizures can evolve to status epileptics resulting in an increased risk of chronic epilepsy and poor prognosis. Therefore, this review aimed to assess the frequency of seizures in patients with TBM, and discuss the etiologies, mechanisms, and characteristics of seizures in TBM. Besides, we have searched the literature to identify the prognostic factors for chronic epilepsy after TBM.

The neurocritical care of tuberculous meningitis

Tuberculous meningitis is the most severe form of tuberculosis and often causes critical illness with high mortality. Two primary management objectives are reducing intracranial pressure, and optimising cerebral perfusion, while killing the bacteria and controlling intracerebral inflammation. However, the evidence base guiding the care of critically ill patients with tuberculous meningitis is poor and many patients do not have access to neurocritical care units. Invasive intracranial pressure monitoring is often unavailable and although new non-invasive monitoring techniques show promise, further evidence for their use is required. Optimal management regimens of neurological complications (eg, hydrocephalus and paradoxical reactions) and of hyponatraemia, which frequently accompanies tuberculous meningitis, remain to be elucidated. Advances in the field of tuberculous meningitis predominantly focus on diagnosis, inflammatory processes, and antituberculosis chemotherapy. However, clinical trials are required to provide robust evidence guiding the most effective supportive, therapeutic, and neurosurgical interventions for tuberculous meningitis that will improve morbidity and mortality.

N-acetyltransferase 2 (NAT2) gene polymorphism as a predisposing factor for phenytoin intoxication in tuberculous meningitis or tuberculoma patients having seizures - A pilot study

Background & objectives:

Simultaneous administration of phenytoin and isoniazid (INH) in tuberculous meningitis (TBM) or tuberculoma patients with seizures results in higher plasma phenytoin level and thus phenytoin intoxication. N-acetyltransferase 2 (NAT2) enzyme catalyses two acetylation reactions in INH metabolism and NAT2 gene polymorphism leads to slow and rapid acetylators. The present study was aimed to evaluate the effect of allelic variants of N-acetyltransferase 2 (NAT2) gene as a predisposing factor for phenytoin toxicity in patients with TBM or tuberculoma having seizures, and taking INH and phenytoin simultaneously.

Methods:

Sixty patients with TBM or tuberculoma with seizures and taking INH and phenytoin simultaneously for a minimum period of seven days were included in study. Plasma phenytoin was measured by high performance liquid chromatography. NAT2 gene polymorphism was studied using restriction fragment length polymorphism and allele specific PCR.

Results:

The patients were grouped into those having phenytoin intoxication and those with normal phenytoin level, and also classified as rapid or slow acetylators by NAT2 genotyping. Genotypic analysis showed that of the seven SNPs (single nucleotide polymorphisms) of NAT2 gene studied, six mutations were found to be associated with phenytoin intoxication. For rs1041983 (C282T), rs1799929 (C481T), rs1799931 (G857A), rs1799930 (G590A), rs1208 (A803G) and rs1801280 (T341C) allelic variants, the proportion of homozygous mutant was higher in phenytoin intoxicated group than in phenytoin non-intoxicated group.

Interpretation & conclusions:

Homozygous mutant allele of NAT2 gene at 481site may act as a predisposing factor for phenytoin intoxication among TBM or tuberculoma patients having seizures.