In a tweet today, UFC heavyweight Stefan Struve announced his retirement from the sport. The Dutchman cited damage to his vestibular system in his ear as the reason; the vestibular system governs a person’s sense of balance. “I’ve had an inner ear issue that I’ve been battling since May last year. I caught a viral infection that damaged my vestibular system and the hearing nerve in my right ear… unfortunately after the fight, some of the issues came back after being hit by a punch on the right ear, it was a punch that should not be an issue normally.