Virial meningitis and tuberculous meningitis sometimes require additional differentiation in clinical practice because their treatment plans are significantly different.

Virial meningitis has a relatively abrupt onset and is caused by a viral infection, generally having a good prognosis. Patients with tuberculous meningitis usually exhibit symptoms of tuberculosis toxicity such as low fever, night sweats, and fatigue before the onset of the disease. Commonly, other forms of tuberculosis can be identified, such as pulmonary tuberculosis or intestinal tuberculosis.

An important diagnostic tool for differentiation is the lumbar puncture. In viral meningitis, the lumbar puncture pressure is generally not particularly high, whereas in tuberculous meningitis, the lumbar puncture pressure is very high, reaching over 400 mm of water column.

Additionally, the cerebrospinal fluid (CSF) in tuberculous meningitis is yellowish, and its protein levels are significantly elevated, as are its white blood cell counts, typically ranging from 50 to 500 × 10^6/L. In tuberculous meningitis, the levels of glucose and chloride in the cerebrospinal fluid are significantly decreased, especially chloride, which is a prominent indicator for diagnosing tuberculous meningitis. In contrast, such clear changes are not observed in the lumbar puncture for viral meningitis. Another aspect to consider is the treatment response; if antiviral treatment is ineffective, the possibility of tuberculous meningitis should be considered.