Early electrodiagnostic abnormalities in acute inflammatory demyelinating polyneuropathy: a retrospective study of 58 patients.

OBJECTIVE: Although patients with acute inflammatory demyelinating polyneuropathy (AIDP) are frequently admitted a few days after symptoms onset, electrodiagnostic (EDX) abnormalities in early AIDP are not well characterized. Our aim was to determine the EDX pattern of early AIDP, and, if needed, to propose new EDX diagnostic criteria.
METHODS: In this monocentric study, we retrospectively reviewed the clinical and EDX data of 58 consecutive AIDP patients in whom EDX studies had been performed within 7 days after disease onset, representing 46% of all GBS patients admitted in our hospital in an 11 years interval.
RESULTS: EDX abnormalities were observed in all patients. The most altered parameters were H reflexes (97% of cases), motor nerve conduction velocities (78%) and distal motor latencies (78%). Only 66% of patients fulfilled the most sensitive published AIDP EDX diagnosis criteria. When using a new set of EDX criteria, which require only one marked EDX abnormality, we observed that 81% of patients could be diagnosed with AIDP.
CONCLUSION: This study suggests that exhaustive EDX studies are always abnormal in early AIDP, and that existing EDX diagnosis criteria can be improved. SIGNIFICANCE: Our findings are useful for the interpretation of EDX studies in early AIDP.