The newswire blub (here) doesn't really make clear what is being talked about with the "BOTOX deaths". The fatalities associated with have NOT been associated with cosmetic uses for wrinkles. The handful of deaths has mostly been in people being treated with high doses (MUCH in excess of cosmetic doses) for esophageal motility disorders and for spastic contractures in children with cerebral palsy.
Your esophagus is essentially a muscular tube, and botox has been used to relax overactive or chronically contracted muscle. A consequence of this is that you can facilitate aspiration of secretions into the lungs and cause acute repiratory distress. Like I mentioned before re. Donde West's death (see here) after cosmetic surgery, this type of aspiration was what I think was the reason she died suddenly.