The Poison frontman was hospitalized Thursday in Nashville as the band toured with Def Leppard, Mötley Crüe and Joan Jett Bret Michaels has encountered a medical emergency while on tour. The Poison frontman, 59, was hospitalized Thursday in Nashville just before the band was set to perform as part of the Stadium Tour with Def Leppard, Mötley Crüe and Joan …