"Browns running back Jamal Lewis was to see more specialists today to determine the cause for apparent brain abnormalities that appeared on a MRI, a source said.

Lewis was placed on injured reserve by the Browns on Wednesday night with "post-concussion symptoms," effectively ending his career five games short of the way he envisioned.

The source said Lewis had been experiencing headaches for some time and recently had vision problems.

Coach Eric Mangini said he was unaware of whether Lewis suffered a blow to the head in what proved to be the last game of his career Sunday in Cincinnati."