Serial electromyographic findings in Guillain-Barré syndrome patients

Abstract

We sought to investigate electromyographic characteristics of Guillain-Barré syndrome (GBS) patients in the recovery phase by using serial electromyography (EMG). We included seven GBS patients and assessed their neurologic function at admission and 2, 3 and 6 months post onset using Hughes Functional Grading Scale scores. All patients underwent serial electromyographic assessment of compound muscle action potentials (CMAPs), mean conduction velocity (MCV), and distal motor latency (DML) of peripheral nerves. F wave was recorded of the median nerve and ulnar nerve. All seven patients had a Hughes Functional Grading Scale score between 3 and 6 at admission, while three patients at 2 months, one patient at 3 months, and no patient at 6 months post GBS onset had a Hughes Functional Grading Scale score between 3 and 6 ( P < 0.05). No F wave was elicited in 41.7% (20/48) of the motor nerves examined at admission, which declined to 25% at 6 months post GBS onset. Decreased amplitude in CMAPs was seen in 50% (24/48) of the motor nerves examined at admission, which decreased to 25% at 6 months ( P < 0.05). Moreover, 60.4% (29/48) of the motor nerves showed abnormal abduction velocity, which declined to 0% at 3 and 6 months post GBS onset ( P < 0.01). In conclusion, GBS patients exhibit a variable course in recovery of electromyographic parameters, and amplitude in CMAPs cannot fully reflect recovery of muscle tone. Conduction block is reversible and in line with rapid muscle tone recovery.