What are the incidence, causes, and treatment options for chronic meningitis presenting acutely?

Chronic Meningitis with Acute Presentation: Incidence and Causes

Chronic meningitis with acute presentation is most commonly caused by cryptococcal infection, tuberculosis, and other fungal pathogens, with approximately one-third of cases remaining undiagnosed despite extensive investigation. 1, 2

Definition and Epidemiology

• Chronic meningitis is defined as inflammation of the meninges with persistence of clinical symptoms, signs, and cerebrospinal fluid (CSF) abnormalities (elevated protein, pleocytosis) for more than 4 weeks 2, 3
• Chronic meningitis accounts for less than 10% of all meningitis cases 1
• In approximately 30-33% of cases, no definitive cause is identified despite extensive investigation 1, 2, 4

Common Etiologies

Infectious Causes:

• Fungal infections:
  • Cryptococcal meningitis (most common fungal cause, especially in immunocompromised patients) 5
  • Other fungi (Histoplasma, Coccidioides, Blastomyces) 6
• Mycobacterial infections:
  • Tuberculosis (M. tuberculosis) 2, 3
  • Atypical mycobacteria 6
• Spirochetal infections:
  • Neurosyphilis (Treponema pallidum) 2
  • Lyme disease (Borrelia burgdorferi) 2
• Partially treated bacterial meningitis 2

Non-infectious Causes:

• Neoplastic conditions:
  • Carcinomatous meningitis 3, 6
  • Lymphomatous meningitis 6
• Inflammatory/Autoimmune disorders:
  • Sarcoidosis 2, 6
  • Behçet's disease 2
  • Systemic lupus erythematosus 6
  • Vasculitis 2
• Drug-induced meningitis 2
• Chemical exposure 1

Clinical Presentation

• Symptoms are often insidious with gradual onset, but can present acutely with:
  • Headache (most common symptom) 7
  • Fever (present in 74-84% of cases) 7
  • Neck stiffness 7
  • Altered mental status 7
• Focal neurological deficits occur in up to 50% of adults with meningitis 8
• Seizures may occur in approximately 13% of cases 8
• Elderly patients often present atypically with more altered mental status and less neck stiffness or fever 7

Diagnostic Approach

• Lumbar puncture with CSF analysis is essential, examining:
  • Opening pressure (often elevated)
  • Cell count and differential (typically lymphocytic predominance)
  • Protein (elevated)
  • Glucose (often decreased)
  • Microbiological studies (cultures, PCR, serology) 7, 3
• Brain imaging (MRI preferred over CT) should be performed before lumbar puncture in patients with focal neurological deficits, new-onset seizures, or severely altered mental status 8
• Blood cultures should be obtained and empiric antibiotics started immediately if lumbar puncture is delayed 7
• Repeated lumbar punctures may be necessary in some cases, though routine repetition is not indicated 8

Treatment Approach

Empiric Treatment:

• For suspected bacterial etiology:
  • Adults aged 18-50 years: Ceftriaxone (2g IV q12h) or cefotaxime plus vancomycin or rifampicin 8, 7
  • Adults >50 years or immunocompromised: Add ampicillin/amoxicillin/penicillin G to cover Listeria 8, 7

Specific Treatment Based on Etiology:

• Cryptococcal meningitis:
  • Initial therapy: Fluconazole 400mg on first day, followed by 200-400mg daily for 10-12 weeks after CSF becomes culture negative 5
  • Suppressive therapy in AIDS patients: Fluconazole 200mg daily 5
• Tuberculous meningitis:
  • Combination therapy with isoniazid, rifampin, pyrazinamide, and ethambutol for extended duration (9-12 months) 6

Complications and Prognosis

• Neurological complications occur frequently:
  • Hearing loss (5-35% of patients) 8, 7
  • Seizures (13%) 8
  • Motor deficits (12%) 8
  • Cognitive defects (9%) 8
  • Hydrocephalus (7%) 8
  • Visual loss (6%) 8
• One in five children may have multiple sequelae 8
• Common sequelae in adults include neurologic deficits due to cerebral infarctions, hearing loss, and cognitive slowness 8

Follow-up Care

• Hearing evaluation should be performed during admission and at follow-up 8
• Neuropsychological evaluation should be considered for patients with cognitive symptoms 8
• Patients, family members, and caregivers should be informed about potential sequelae 8

Pitfalls to Avoid

• Delaying antibiotic treatment while awaiting diagnostic results 7
• Failing to recognize atypical presentations, especially in elderly patients 7
• Overlooking the need for ampicillin in older adults to cover Listeria 8, 7
• Neglecting to assess for hearing loss and other sequelae before discharge 8, 7
• Assuming a negative initial workup excludes serious pathology; repeated investigations may be necessary 4