Complications

Potential complications of concussion include:

• Post-traumatic headaches. Some people experience concussion-related headaches up to seven days after a brain injury.
• Post-traumatic vertigo. Some people experience a sense of spinning or dizziness for days, weeks or months after a brain injury.
• Post-concussion syndrome. A small proportion of people (15% to 20%) may have symptoms including headaches, dizziness and thinking difficulties that persist beyond three weeks. If these symptoms persist beyond three months, this becomes characterized as post-concussion syndrome.
• Cumulative effects of multiple brain injuries. Active research is currently underway to study the effects of repeated head injuries that don't cause symptoms (subconcussive injury). At this time, there's no conclusive evidence indicating that repeated brain injuries contribute to cumulative effects.

• Second impact syndrome. Rarely, experiencing a second concussion before signs and symptoms of a first concussion have resolved may result in rapid and usually fatal brain swelling.

  It's important for athletes never to return to sports while they're still experiencing signs and symptoms of concussion.