Okoye revealed to Rainer Sabin of The Dallas Morning News that he was put in a medically induced coma in early April of 2013 after contracting anti-NMDA receptor encephalitis, a rare and potentially fatal disease.
The autoimmune syndrome causes brain inflammation, as antibodies interfere with cell communication, causing damage to the neurons.
Okoye doesn't remember anything that happened from March 15, 2013, to Aug. 7 of that year. When awakened from his coma in early July of 2013, he had lost 78 pounds and -- according to Sabin -- "spoke gibberish" at times and "laughed for no apparent reason."
As motor functions gradually returned, Okoye began having moments of lucidity while his mother stayed by his side on a daily basis.
"Pretty much getting back to the mix of things," Okoye explained. "Walking, eating, all that stuff."
It wasn't until October that he began to feel like himself again. By December, he knew he wanted to play football during the 2014 season.
At defensive coordinator Rod Marinelli's behest, the Cowboys signed Okoye to a two-year contract with no guarantees in May. On the non-football illness list, he has been doing conditioning work away from his teammates.
In today's football culture, any injury or condition involving the brain is handled with extreme caution. The team's medical staff has been neuro-site testing to create a baseline for Okoye.
"He's not ready to get in the game yet," Cowboys head athletic trainer Jim Maurer said. "But he's taking these baby steps to come back."
Okoye was cleared to participate in contact drills Thursday. The youngest player ever selected in the first round of the NFL draft could see game action a year after his faculties returned.