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.
Post-concussion syndrome
If another blow to the head occurs after a concussion but before its symptoms have gone away, there is a slight risk of developing the serious second-impact syndrome (SIS). In SIS, the brain rapidly swells, greatly increasing intracranial pressure. People who have repeated mild head injuries over a prolonged period, such as boxers and Gridiron football players, are at risk for chronic traumatic encephalopathy (or the related variant dementia pugilistica), a severe, chronic disorder involving a decline in mental and physical abilities.