Answer
Concussion, a head injury that can cause a range of symptoms including headaches, dizziness, and confusion, contributed to Lehner's health struggles. The injury, which can occur during contact sports like hockey, can have long-lasting effects on an individual's physical and mental well-being. In Lehner's case, the concussion may have exacerbated his existing health issues, making it more difficult for him to manage his symptoms and perform at his best.