In Guillain-Barré syndrome, what laboratory finding is typically noted in lumbar puncture?

In Guillain-Barré syndrome (GBS), the characteristic finding in a lumbar puncture is albuminocytologic dissociation. This refers to a situation in which there is a high protein concentration in the cerebrospinal fluid (CSF) with a normal white blood cell (WBC) count. This finding is significant because it helps differentiate GBS from other conditions that may present with similar symptoms, such as infections or inflammatory processes within the central nervous system, where typically both the protein levels and WBC counts would be elevated.

The presence of albuminocytologic dissociation indicates that there is damage to the nerve roots and peripheral nervous system, leading to the increased permeability of the blood-nerve barrier, which allows protein to leak into the CSF without a corresponding increase in WBCs. This finding is one of the hallmark diagnostic criteria for GBS and is important for clinicians when evaluating patients with suspected neurological conditions.