Which CSF finding is classically seen in Guillain-Barré syndrome?

• A. Low CSF protein
• B. Elevated CSF protein
• C. Elevated CSF glucose
• D. Decreased opening pressure

Answer: (B)

In Guillain-Barré syndrome, the CSF often shows albuminocytologic dissociation: a high protein level with a normal white blood cell count. This happens because demyelination of the peripheral nerves increases permeability of the blood-nerve barrier, allowing proteins to leak into the CSF, while there isn’t an accompanying inflammatory cell influx in the CSF. Glucose stays normal and opening pressure is typically normal as well. The protein rise usually appears after about a week from symptom onset, though it can be absent early on. So the classic finding is elevated CSF protein.