Bruschi, 31, was admitted Wednesday night after complaining of persistent headaches. Initial tests revealed the stroke-like symptoms he suffered likely were caused by a broken blood vessel in his head, according to the Boston Globe.
The paper also reported Bruschi suffered blurred vision and partial paralysis.
The paralysis reportedly is gone and he is said to be in good condition.
The Patriots said in a statement, "Tedy is in good condition and will be held for further evaluations."
The nine-year veteran out of Arizona was a key factor in the Patriots' recently winning their third Super Bowl in four years.
Last Sunday, he played in the annual season-ending Pro Bowl for the first time in his career.
During his week-long stay in Honolulu, he did not complain of having any health difficulties.