In the wake of an off-kilter performance of the National Anthem at a televised auto race in March, country artist John Michael Montgomery has revealed that he suffers from acoustic neuroma, "which can seriously affect my hearing and balance," he explains on his official Web site.

Montgomery says he received many emails from fans about his "less than perfect performance" at the NASCAR event in Atlanta, many of which accused him of drunkenness.

"The side-effect of loss of balance that makes me feel like I am falling does not bother me all the time but is more noticeable when I am tired and fatigued," he says. "Better judgment might have been to notify the promoters instead of trying to perform the anthem. However, due to my contractual obligation I decided to go ahead with the performance. In hindsight, I shouldn't have."

The artist goes on to apologize to anyone his performance of the Anthem may have offended and pledges to work with his physicians to remedy his condition. "The good news is my doctors feel that there is a very good chance that the situation can be corrected and it should not affect any of the tour dates we have scheduled," he says.

Montgomery has dates scattered over the next few months, according to his site. The next one comes April 8 in Kennesaw, Ga. He's out supporting last year's "Letters From Home" (Warner Bros.), which debuted at No. 3 on Billboard's Top Country Albums chart and No. 31 on The Billboard 200.