[Mechanism of F-wave conduction delay in acute Guillain-Barré syndrome].
We measured M-wave and F-wave conduction time between the wrist and the elbow in 16 median nerves of acute phase of Guillain-Barré syndrome. Studies were carried out within 14 days after the onset of the weakness. In 20 healthy subjects, conduction times of M- and F-waves were almost similar, while F-wave conduction time was longer than the corresponding M-wave conduction time in the acute phase of the illness. This dissociation between the F-wave and the M-wave conduction time was exaggerated when the minimal F-latency was longer. The results suggest that an F-wave with the minimal latency does not always conduct through the fastest motor fiber which determines the onset of M-wave, but may represent a conduction through motor fibers with slower velocity. This disproportionately-prolonged conduction time of the F-wave was never seen during the recovery phase, 12 weeks after the onset of the illness. A conduction block of the fastest motor fiber in the proximal segment is supposed to be a cause of the conduction delay of the F-wave with minimal latency in the acute stage of the Guillain-Barré syndrome.
Baba
M
M
Department of Neurology, Hirosaki University School of Medicine.
Matsunaga
M
M
D000208:Acute Disease; D000328:Adult; D004568:Electrodiagnosis; D006801:Humans; D008475:Median Nerve / Q000503:physiopathology; D008875:Middle Aged; D009431:Neural Conduction; D011129:Polyradiculoneuropathy / Q000503:physiopathology*; D011930:Reaction Time