Complex sentence: Despite aggressive chelation therapy, her condition rapidly deteriorated; three weeks after the first neurological symptoms appeared, Wetterhahn lapsed into what appeared to be a vegetative state punctuated by periods of extreme agitation.
Split into simpler sentences: Despite aggressive chelation therapy, her condition rapidly deteriorated. Three weeks after the first neurological symptoms appeared, Wetterhahn lapsed into what appeared to be a vegetative state punctuated by periods of extreme agitation.