Griffith Joyner was one of 25% of the population to have a congenital weakness of a blood vessel in the brain, called cavernous angioma, said Dr. Barbara Zaias, a forensic neuropathologist with the coroner’s office. She said 10% to 15% of those people suffer from seizures.

In most instances, though, the condition doesn’t cause problems, and many people live their lives unaware of it. Other times it may cause headaches, bleeding or seizures, Zaias said.

Fukumoto said he knew of nothing in the medical literature that showed this condition could be brought on by using performance-enhancing drugs, such as steroids.

Charles Yesalis, an expert on performance-enhancing drugs at Penn State, said the autopsy would not definitively show whether Griffith Joyner ever used steroids or human growth hormone. The most long-lasting steroids leave the body within a year, he said, and Griffith Joyner retired from competition nearly a decade ago.

Griffith Joyner had suffered a seizure previously, during a flight from Los Angeles to St. Louis in 1996, and she was hospitalized briefly. After her death, her brother said it was the result of stress. On Thursday, the Joyner family and coroner’s doctors declined to take questions about the athlete’s medical history.

Zaias said a cavernous angioma might show up during sophisticated imaging tests, such as an MRI or a CTI, but even then it might stay hidden.

The day she died, Griffith Joyner’s husband called paramedics from their Mission Viejo home at about 6:30 a.m. and said his wife was not breathing. Joyner told investigators when he had last checked on his wife at 1 a.m. she was sleeping.

Coroner’s office officials said Griffith Joyner had a healthy heart.

Griffith Joyner died almost 10 years after winning the 100-meter gold medal, the first of three she won in the 1988 Olympics.

She later won the 200 meters and was a member of the teams that won the 400-meter relay and came in second in the 1,600-meter relay. She became the first woman to win four medals in track at one Olympics and still holds the world record in the 100–10.49 seconds.

Because of her muscular build and dominance of the sport, Griffith Joyner came under suspicion for using steroids or human growth hormones, but she never failed a drug test. The Olympic champion credited her success to a new diet and extensive weightlifting.