Which CSF finding is classic in Guillain-Barré syndrome?

• A. Elevated protein with normal cell count
• B. Elevated protein with increased cell count
• C. Low protein with normal cell count
• D. Normal protein with normal cell count

Answer: (A)

In Guillain-Barré syndrome, the CSF often shows albuminocytologic dissociation: elevated protein with a normal white blood cell count. This happens because immune-mediated demyelination of peripheral nerves increases the permeability of the blood-nerve barrier, allowing proteins to leak into the CSF, while the meninges and central inflammatory cell response are not involved, so cells stay low. Timing matters—protein may be normal early and rise over the first week or two. Other patterns, like elevated protein with many cells or low protein, do not fit the classic GBS picture, making this combination the best clue.