[Chronic meningitis: aetiologies, diagnosis and treatment]

Diagnostic importance of eosinophilic meningitis in HIV-positive and HIV-negative patients

The presence of eosinophils in the cerebrospinal fluid (CSF) should always be considered abnormal. This study aimed to evaluate the causes of eosinophils in the CSF of patients who are HIV positive and HIV negative. This is the first study of eosinophils in the CSF of patients who are HIV-positive. This was a retrospective study of CSF reports from 1996 to 2005, patients were selected based on the presence of eosinophils in the CSF. We analyzed 20,008 CSF reports; eosinophils were present in 5%. The median and interquartile range (IQR) of eosinophils was 2% (1%, 4%). Eosinophilic meningitis (CSF eosinophils ≥ 10%) was present in 12% of the samples. The main etiologies were infectious diseases as follows: neurocysticercosis, Cryptococcus sp. meningitis, and acute bacterial meningitis. In HIV-positive cases, all causes were by infectious disease, the main pathogen being Cryptococcus sp. The probability of neurocysticercosis in a patient from an endemic region who is HIV-negative and has CSF eosinophils more than 10% was five times higher compared to a person without eosinophilic meningitis. There was a weak positive correlation between CSF eosinophils and increased serum eosinophils. Among the HIV-negative cases, the most frequent non-infectious causes were cerebrovascular syndromes, of these hemorrhage (91.5%). In the HIV-positive group, there were no cases of non-infectious cerebral disease. CSF eosinophils are suggestive of disease. The causes must be investigated, considering the most prevalent infectious diseases in the region.

Chronic meningitis

Chronic meningitis is an inflammation of the meninges with subacute onset and persisting cerebrospinal fluid (CSF) abnormalities lasting for at least one month. Several non-infectious and infectious etiologies are known to be causative. The wide range of different etiologies renders the approach to patients with this syndrome particularly difficult. There is no standardized diagnostic procedure, thus, taking an in depth history combined with a complete physical examination is mandatory in every patient.This review aims to present the current knowledge on etiology, neurological course of disease, diagnostic and therapeutic management steps of patients presenting with clinical signs and symptoms of chronic meningitis and meningoencephalitis. Still, the etiology of one third of patients remains unclear, reflecting the diagnostic challenge of this syndrome for each physician or neurologist, respectively. However, most patients with idiopathic chronic meningitis have a relatively good outcome.

An unusual case of chronic meningitis

BACKGROUND

Chronic meningitis is defined as symptoms and signs of meningeal inflammation and persisting cerebrospinal fluid abnormalities such as elevated protein level and pleocytosis for at least one month.

CASE PRESENTATION

A 62-year-old woman, of unremarkable past medical history, was admitted to hospital for investigation of a four-week history of vomiting, malaise an associated hyponatraemia. She had a low-grade pyrexia with normal inflammatory markers. A CT brain was unremarkable and a contrast MRI brain revealed sub-acute infarction of the right frontal cortex but with no evidence of meningeal enhancement. Due to increasing confusion and patient clinical deterioration a lumbar puncture was performed at 17 days post admission. This revealed gram-negative coccobacilli in the CSF, which was identified as Neisseria meningitidis group B. The patient made a dramatic recovery with high-dose intravenous ceftriaxone antibiotic therapy for meningococcal meningitis.

CONCLUSIONS

1) Chronic bacterial meningitis may present highly atypically, particularly in the older adult. 2) There may be an absent or reduced febrile response, without a rise in inflammatory markers, despite a very unwell patient. 3) Early lumbar puncture is to be encouraged as it is essential to confirm the diagnosis.4) Despite a delayed diagnosis appropriate antibiotic therapy can still lead to a good outcome.