NEW YORK -- Dirk Kaufman, 51, was riding his bike last March when he was hit by a car. He wound up in the emergency room at Bellevue hospital.
What happened was a concussion with memory loss and confusion. In Kaufman's case the injury did not show up on a CT scan. But less obvious cases of concussion are harder to diagnose, says neurosurgeon doctor Uzma Samadani.