In late 1997 while on a publicity tour for Kull the Conqueror and between the fourth and fifth seasons of Hercules, the newly engaged Sorbo experienced an aneurysm in his shoulder which caused four strokes. As a result, he was weakened for the next several years, a condition kept secret from the public while he recovered. During the last two seasons of Hercules (the fifth and sixth, which aired in 1998 and 1999), Sorbo had a reduced filming schedule to accommodate his condition, and more guest stars were featured in the show in order to reduce Sorbo's duties. The strokes, thought to be triggered when chiropractic manipulation of his shoulder released blood clots from the aneurysm, left Sorbo with a permanent 10 percent vision loss, weakness, impaired balance, and migraines. In his 2011 autobiography True Strength, Sorbo revealed the details of his injury and how his wife Sam helped him recover.