Westerfield, 53, was riding her Harley past Indian Hills Golf Club in Murfreesboro, Tenn., when she was struck in the face by an unidentified golfer's ball.
Amazingly, she was able to keep from crashing even though the ball knocked out several of her teeth and sliced her lip,WKRN-TV reported.
Although she was wearing a helmet, it did not have a protective face guard.
Westerfield was taken to Middle Tennessee Medical Center, where she was treated and released, but told authorities that the moment the ball hit was like having her teeth pushed backwards, the Daily Mail reported.
Westerfield's nerve damage is so severe that she cannot feel anything in her mouth, including pain, and that pains golfers like Jeff Hall, who told WKRN-TV that he didn't see the ball hit Westerfield, but heard screams and ran to her location.
"It's terrible. I feel bad for her. I can't imagine it," Hall said.
No charges have been filed, and a source at Indian Hills Golf Club said this is the first time someone has been injured by a flying golf ball at the course.