Changes in electrophysiological findings suggestive of demyelination following Guillain-Barré syndrome: A retrospective study.

Introduction/aims: Acute inflammatory demyelinating polyradiculoneuropathy (AIDP) is the most common form of Guillain-Barré syndrome (GBS) in Western countries. However, electrophysiological descriptions of changes in abnormalities suggestive of demyelination after an AIDP episode are rare. We aimed to describe the clinical and electrophysiological features of AIDP patients after the acute episode, to investigate changes in abnormalities suggestive of demyelination and to compare with electrophysiological features of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).

Methods: We reviewed the clinical and electrophysiological characteristics of 61 patients followed at regular intervals after the AIDP episode.

Results: We detected early electrophysiological abnormalities from the first nerve conduction studies (NCS) performed before 3 wk. Abnormalities suggestive of demyelination worsened on subsequent examinations. This worsening continued after more than 3 mo of follow-up for some parameters. We also found the persistence of abnormalities suggestive of demyelination for long periods after the acute episode, beyond 18 mo of follow-up, despite clinical improvement in most patients.

Discussion: In AIDP, NCS findings continue to worsen several weeks or even months after the onset of symptoms, and "CIDP-like" abnormalities suggestive of demyelination may persist for a long period of time, in contrast to the existing literature and the usually favorable clinical course. Thus, the discovery of conduction abnormalities on NCS performed long after an AIDP should always be interpreted according to the clinical context and not systematically lead to a diagnosis of CIDP.