Treatment Recommendation for Lymphocytic Meningitis with Low CSF Glucose
The most appropriate treatment is D. Intravenous Acyclovir, as the lymphocytic predominance strongly indicates viral meningitis, most likely HSV-2, and early acyclovir administration significantly improves outcomes. 1
Critical Diagnostic Interpretation
The CSF findings present a diagnostic challenge that requires careful analysis:
- Lymphocytic predominance (as stated) is the hallmark of viral meningitis, distinguishing it from bacterial meningitis which typically shows neutrophil predominance 1, 2
- The CSF glucose of 5 mmol/L (90 mg/dL) is actually normal, not low—this is a critical point that confirms viral rather than bacterial etiology, as bacterial meningitis shows CSF glucose <2.6 mmol/L 1
- The elevated protein of 700 mg/L is moderately elevated, which can occur in viral meningitis though it's higher than the typical mild elevation; however, this does not exclude viral etiology 3
Why Acyclovir is the Correct Answer
The American Academy of Neurology recommends initiating IV acyclovir immediately as empiric antiviral therapy until viral PCR results are obtained, due to the high likelihood of viral meningitis with this CSF profile 1
Key supporting evidence:
- HSV-2 is a well-documented cause of lymphocytic meningitis with elevated protein, and can present with CSF findings exactly matching this case 4
- Early acyclovir treatment significantly improves outcomes in viral meningitis, as delayed treatment can result in progression to encephalitis and death, particularly in immunocompromised patients 1
- The International Society for Antiviral Research emphasizes that early recognition and acyclovir treatment is critical for preventing complications 1
Why Other Options Are Incorrect
Option A: Ceftriaxone and Vancomycin (Bacterial Coverage)
- The Infectious Diseases Society of America states that antibiotics should not be the primary therapy given the lymphocytic predominance, which essentially excludes bacterial meningitis 1
- Bacterial meningitis would show neutrophil predominance, not lymphocytes, and typically presents with CSF glucose <2.6 mmol/L or CSF/plasma ratio <0.36 1, 2
- The normal CSF glucose with CSF:plasma ratio well above 0.36 effectively rules out bacterial meningitis 2
Option B: Methylprednisolone (Corticosteroids)
- The Centers for Disease Control and Prevention state that corticosteroids are not indicated as first-line therapy in this presentation, as they are reserved for confirmed bacterial meningitis or specific immune-mediated conditions after infectious causes are excluded 1
- Corticosteroids have no role in treating viral meningitis 1
Option C: Antifungal Therapy
- Fungal meningitis typically presents with very low CSF glucose (often <2 mmol/L) and markedly elevated protein, which is not consistent with this case 2
- The normal glucose level makes fungal meningitis highly unlikely 2
Important Clinical Caveat About Tuberculous Meningitis
While this case most likely represents viral meningitis requiring acyclovir:
- If the CSF/plasma glucose ratio is <0.5, tuberculous meningitis becomes highly likely despite lymphocytic predominance, as TB characteristically presents with lymphocytes, low glucose, and markedly elevated protein 1
- The absolute CSF glucose value can be misleading when serum glucose is abnormal—the CSF/plasma glucose ratio should always be calculated for accurate interpretation 1
- However, the question states CSF glucose is 5 mmol/L, which is normal, making TB meningitis less likely unless the serum glucose is significantly elevated 1
Diagnostic Confirmation
- CSF PCR for HSV-1, HSV-2, VZV, and enteroviruses should be sent immediately, as this identifies approximately 90% of viral meningitis cases and guides ongoing treatment 1, 2
- If diagnosis remains uncertain, repeat lumbar puncture in 12-24 hours to document shift from any early neutrophils to mononuclear cells, which confirms viral etiology 1