Viral Meningitis and Elevated Opening Pressure

Clinical Presentation and Diagnosis

The UK Joint Specialist Societies guidelines state that viral meningitis typically presents with normal or mildly raised opening pressure, with a normal range of 12-20 cm CSF, according to the Journal of Infection guidelines 1
The CSF white cell count in viral meningitis is typically raised with lymphocytic predominance, though neutrophils may predominate early in enteroviral meningitis, as reported in the Journal of Infection 1
CSF protein is mildly raised and glucose is normal or slightly low in viral meningitis, helping distinguish it from bacterial causes, as stated in the Journal of Infection guidelines 1

Opening pressure ≥250 mm H₂O represents a critical threshold requiring therapeutic intervention, based on guidelines from the management of fungal meningitis 2
For pressures ≥250 mm H₂O, CSF drainage should be performed to achieve closing pressure <200 mm H₂O or reduce by 50% of initial opening pressure, as recommended in the guidelines for managing elevated ICP 2
Brain imaging, such as CT or MRI, must be performed before lumbar puncture in patients with focal neurological signs or altered mental status to rule out mass lesions, according to the guidelines from Praxis Medical Insights 3, 4

The presence of significantly elevated opening pressure with viral CSF profile should prompt careful consideration of whether bacterial meningitis has been adequately excluded, particularly if antibiotics were given prior to lumbar puncture, as noted in the Journal of Infection guidelines 1
CSF sterilization may occur within 2 hours for meningococcus and 4 hours for pneumococcus after antibiotic administration, potentially leaving a "viral-appearing" CSF profile in partially treated bacterial meningitis, as reported in the Journal of Infection 1