Doctors called on Friday for a rethink of shaken-baby syndrome after researchers cast doubt on one of the symptoms used to identify it. The syndrome results from violently shaking an infant and is recognized by bleeding around the brain and from the eye, along with brain damage. It made international headlines in 1997 when British nanny Louise Woodward was convicted of killing a baby boy in Massachusetts by shaking him violently. Now British and American scientists said there are serious questions about the syndrome and how it is diagnosed.