In patients being evaluated for brain death, which abnormal movements are definitively known to still be consistent with brain death and which are possibly consistent with brain death but lack definitive evidence?

This is indeed a challenging question, one that I continue to grapple with as a neurointensivist. Fortunately, most brain-dead patients do not exhibit any movements in response to noxious stimuli, but some case series report reflexive movement in up to 75% of cases. The classic teaching is that only...