Early Electrodiagnostic Findings in Guillain-Barré Syndrome

Abstract

The H reflex is the most sensitive test for early GBS. Upper extremity SNAPs are also frequently abnormal in early GBS. Absent H response, abnormal F wave, and abnormal upper extremity SNAP combined with a normal sural SNAP are characteristic of early GBS. If multiple nerves are tested, definite diagnosis is possible in half the patients, but not until the fifth day after the onset of symptoms.