(HealthDay News) -- A concussion is a brain injury caused by a violent blow to the head.

The American Association of Neurological Surgeons says common warning signs of concussion include:

• Persistent headache.
• Vision problems.
• Dizziness, nausea or vomiting.
• Impaired balance, confusion, trouble concentrating or memory loss.
• Ringing in the ears.
• Sensitivity to light.
• Diminished senses of taste or smell.