Joan Kennedy (search), the former wife of U.S. Sen. Edward M. Kennedy, was hospitalized with a concussion and a broken shoulder early Tuesday morning after a passer-by found her lying in a Boston street, said her son, U.S. Rep. Patrick Kennedy.

Kennedy, 68, was taken to Tufts New England Medical Center at about 3 a.m. on Tuesday, said Patrick Kennedy, D-R.I.

"We're indebted to some anonymous pedestrian who found her and picked her up and got her help," Patrick Kennedy told the Boston Herald. "I'm enormously grateful for whoever it is out there who did that. She wouldn't be here in this hospital, recuperating, if that person hadn't called and gotten someone to come."

Patrick Kennedy (search) was somber and visibly shaken at the hospital and said he was "very concerned" for the welfare of his mother, according to the newspaper.

Details of exactly what happened and how she ended up in the street were unclear. There was no police report on the incident. Joan Kennedy, who splits time between a home on Cape Cod and a Boston condominium, has struggled with alcoholism in the past.

"You want to make sure there is someone there for her all the time ... but at the same time you don't want to encroach on her privacy too much," Patrick Kennedy told the Herald. "When things like this happen, it makes you feel as though maybe you should have done more to make sure there is someone with her 24/7 and perhaps that might become necessary."