wstrząśnienie mózgu in inglese:

The doctors think it's a concussion.

The little girl got concussion from falling on her head

This may result in a more serious head injury (e.g. concussion), which may make them feel sick or drowsy.

If a person suffers a blow to the head, the brain can be shaken inside the skull. This is called concussion. It tends to result in a short loss of consciousness.

I don't think she has a concussion. Her pupils react correctly to the light, for starters.

After that final in Champions League, Hospital in USA did examination on Karius and proved that he had concussion