In the most recent DAN report, there is only one fatality that is assumed to be due to CNS toxicity. It is a bizarre case. The diver was an experienced technical diver who was planning a decompression dive using EANx 80--80% O2. He would have, of course, planned to use that only during the shallowest portion of his decompression schedule. He somehow got separated (I am doing this from memory) and was later found dead. The assumption of CNS is due to the fact that his regular tanks were full and his 80% tank was well used. He apparently somehow had mistakenly used 80% while at depth.
There were no O2 toxicity cases in the previous report.
The only other case I know of for sure is even more bizarre. In this case the diver was luckily enough to realize he was about to tox while next to the instructor (George Georgitsis) in a training dive. He was safely brought to the surface despite a seizure, suffering no ill effects. The diver was responsible for doing all the mixes for the dive the day before, and in the confusion he had accidentally put O2 into his tanks when he was supposed to be adding helium, so he got roughly twice the percentage of O2 he was expecting. He compounded the error by not analyzing.
Thus, in the only 2 cases I know, the divers had ridiculously high PPO2's, and they were diving them for a while before they took the hit.