Post-concussion syndrome
About 10% of people with PCS develop sensitivity to light or noise, about 5% experience a decreased sense of taste or smell, and about 14% report blurred vision. People may also have double vision or ringing in the ears, also called tinnitus. PCS may cause insomnia, fatigue, or other problems with sleep.
Concussions in sport
Playing through concussion makes people more vulnerable to getting hit again, and that is why most sports have test that trainers will perform to prevent getting hit a second time. A second blow can cause a rare condition known as second-impact syndrome, which can result in severe injury or death. Second-impact syndrome is when an athlete suffers a second head injury before the brain has adequate time to heal in between concussions.