P634: The electrophysiological differences between acquired inflammatory demyelinating polyneuropathies

Abstract

Question: Acquired inflammatory demyelinating polyneuropathies (AcIDP) are the most common autoimmune neuropathies. AcIDPs are categorized into 3groups as acute (GBS), sub-acute (SIDP) and chronic (CIDP). The electrophysiological differences between the AcIDPs have not been defined in the literature clearly. The purpose of this study is to reveal the electrophysiological differences between 3 groups AcIDPs. Methods: GBS was diagnosed when the progression period is less than 4 weeks, SIDP was diagnosed when the period was between 4 and 8 weeks, and CIPD was diagnosed when the period was longer than 8 weeks and the history of previous episodes. Results: Within the study, 129 GBS, 123 CIDP and 31 SIDP patients were included. Whereas mean sensory nerve amplitudes of GBS patients were statistically significantly higher than the CIDP and SIDP patients, motor nerve amplitudes were lower. Both mean sensory and motor NCV of GBS patients were higher than the CIDP and SIDP patients. Mean F wave latency of SIDP patients were significantly longer than the CIDP and GBS patients. Mean motor distal latencies were slightly longer in SIDP patients, but the difference was not statistically significant. Conclusion: Nerve conduction studies of GBS patients were better than other AcIDPs except from the motor amplitudes. Changes in nerve potential amplitudes indicate nerve regeneration, nerve degeneration, or the presence of conduction block. The lower motor amplitudes of GBS patients can be arisen from the conduction block.