this twisting was due to a "congential ganglionic fold" he was born with it.
They also come to the conclusion that he had a violent heart attack from the lab work and the evidence they reviewed.
Here is a quote form the man who did the official review of Elvis's autopsy in 1994.
In 1994, the autopsy into Presley's death was re-opened. Coroner Dr. Joseph Davis declared: "There is nothing in any of the data that supports a death from drugs [i.e. drug overdose]. In fact, everything points to a sudden, violent heart attack." However, there is little doubt that long-term drug misuse caused his premature death.