When do you redose IVIG in GBS patients who were under-treated and are worsening?

Based on recently published data from the randomized SID-GBS trial, this approach is not a good idea. A second course of IVIG not only did not clearly benefit patients with GBS with poor prognosis, but it was associated with a significantly higher risk of adverse events including thromboembolism.

Walgaard et al., PMID 33743237

PLEX is in my opinion, the way to go with intractable GBS or any type of demyelinating or primarily demyelinating neuropathy that is going through an acute worsening with threatening presentation including bulbar symptoms or signs. This maybe followed by IVIg but only if the patient is out of the critical phase. Repeating PLEX may have to be done again with steroids intravenously and supportive care in the hospital to get the "flare-up" under control then move into second line treatments like IVIg. Overall, no room for IVIg in this case.