A 44 year old with a headache and signs of meningitis has an LP performed1. Three causes:

Infection – partially treated bacterial/ aseptic

Autoimmune/ Malignancy

SAH

based on CSF – likely to be viral meningitis

1. Four  Abnormalities:

Low Polymorphs/ high lymphocytes/ high protein/ normal glucose/ no bacteria indicates viral

Against viral is turbid CSF

Against SAH is reducing RCC in 3 samples almost down to 0

Malignancy/ autoimmune unlikely based on above, but must be kept in mind.

1. Other tests:

CSF

• viral PCR/ nucleic acid detection test for HSV/ enterovirus/ VZV/ other (HIV/Cryptococcus etc)
• bacterial PCR/ nucleic acid detection test for Neisseria M/ Strep Pneumoniae
• India ink – cryptococcus
• Await culture
• Auto immune tests as indicated

Other

•  bloods, including cultures if indicated
• CXR
• Urine

This patient developed shingles  a couple of days later and her CSF had VZV