The value of F wave in early diagnosis of Guillian-Barre syndrome

Objective To explore the characteristics of electrodiagnostic abnormalities of Guillain-Barre syndrom(GBS) and to discuss the value of F wave in early diagnosis of GBS.Methods We retrospectively reviewed the neurophysiological studies of 47 patients with GBS discharged from our hospital in 2005 to 2009.We study the motor and sensory nerve conduction velocity and F wave.The total number of nerves studied was 329 for motor nerve,235 for sensory nerve,329 for F wave.Results In the first week from onset,the characteristics of electrodiagnostic abnormalities was 54% patients with abnomal F wave,6% patients with slowed motor nerve conduction velocity,38% patients with prolonged distal lantency,and 57% patients with declined amplitude of compound nerve action potention,30% patients with declined amplitude of sensory nerve action potential,21% patients with slowed sensory nerve conduction velocity.None of patient have conduction block.Conclusion In the early stage of GBS,especially with the pathology type of demyelination,F wave is more sensitive than nerve conduction velocity and distal lantency.The prolonged of F wave lantency and declined of frequency is helpful in the early diagnosis of GBS.