Very early electrodiagnostic findings in Guillain-Barré syndrome.

Electrodiagnostic studies play a key role in the evaluation of patients with Guillain-Barré syndrome (GBS). However, at early stages patients may not meet current neurophysiologic criteria. We report electrodiagnostic findings for 18 patients with suspected GBS within 4 days of clinical onset. Fifteen patients (83%) showed abnormality in the motor nerve conduction study. Prolonged distal motor latency (DML) was the most frequent demyelinating parameter (seen in 55% of patients). Abnormal late responses were noted in 14 patients (77%). Electrodiagnostic study of cranial nerves was abnormal in eight (44%), and motor nerve conduction velocity was abnormal in only six patients (23%). The study shows a predominant motor neuropathy pattern followed by a sural-sparing pattern; no patients showed a strictly normal electrodiagnostic study. Reduced distal compound muscle action potential and prolonged DML in the demyelinating range were associated with severity of GBS on admission. After the electrodiagnostic study, 5 patients (27%) already fulfilled electrodiagnostic criteria for acute inflammatory demyelinating polyneuropathy (AIDP), 1 (5%) for the axonal variant of GBS, and 13 (72%) were classified as equivocal. We conclude that exhaustive electrodiagnostic studies of patients with suspected GBS in very early stages are useful in the diagnosis and management of the condition.