It's a subject that has polarized the international community of child-abuse experts, confronted jurors at murder trials and led to a review of the deaths of hundreds of British babies.

The controversy over shaken baby syndrome has gained urgency in Canada after Ontario's top forensic pathologist cast doubt on the diagnosis at the inquiry into the actions of disgraced pathologist Charles Smith.

Diagnosis of the syndrome, typically made when pathologists find a combination of brain swelling, retinal bleeding and tissue damage to brain linings, has won broad acceptance since it was first coined in the early 1970s.

But in recent years, some researchers have come to believe that symptoms thought to be the hallmarks of shaken baby syndrome, considered a deadly form of child abuse, can be caused accidentally.

Skepticism about SBS is now so great that Ontario should review the 142 baby deaths attributed to shaking since 1986, Ontario's chief pathologist, Michael Pollanen, testified at the Goudge inquiry last week.
That would follow Britain's massive rev

iew of 297 baby-death convictions - ordered after Angela Cannings, a British mother convicted of murdering her two infant sons, was freed on appeal in December, 2003. At the conclusion of Britain's Goldsmith review last February, three convictions were ordered to be reconsidered by the courts.

But some high-profile experts say there is no need for a similar review in Canada and argue that skepticism surrounding the diagnosis has been overstated.

Such a review "would be a complete waste of money," said Ronald Barr, a child-abuse expert and professor of pediatrics at the University of British Columbia and adviser to the National Centre on Shaken Baby Syndrome, based in Utah.

SBS remains a solid diagnosis when accompanied by the proper detective work, Dr. Barr said.

"There is no significant segment of the scientific community that has come to believe that the same symptoms can be found in babies with accidental falls," he said. "That's absolutely not true. There are a few."

The diagnosis is recognized by several leading medical bodies.

"SBS is a condition that occurs when an infant or child is shaken violently, usually by a parent or caregiver," the Canadian Paediatric Society wrote in a 2005 joint statement on SBS, co-signed by Health Canada, the Child Welfare League of Canada and the Canadian Association of Chiefs of Police, among other bodies.

"Shaken baby syndrome is a serious and clearly definable form of child abuse," the American Academy of Pediatrics states on its website.

Still, some doctors have concluded that the symptoms associated with SBS can be found in babies who suffer an accidental blow to the head or an innocent fall.
John Plunkett, an American pathologist, has published research showing that small children get the same types of brain injuries by falling from as low as one metre.
Dr. Plunkett cites several studies by other researchers that have shown the "triad" of symptoms associated with SBS can also be caused by accident or illness - short falls, genetic conditions and viral infections.

Dr. Plunkett and a co-author listed those findings in an editorial published in a 2004 issue of the British Medical Journal, concluding that "we need to reconsider the diagnostic criteria, if not the existence, of shaken baby syndrome."

That editorial elicited a harsh response letter signed by 106 pediatricians and medical experts. Among them were Carole Jenny, professor of pediatrics at Brown University School of Medicine in Rhode Island, who is studying the biomechanics of accidental and inflicted head trauma in infants, using crash test dummies.

While she agrees that research has shown that some other things may cause the same symptoms as those shown in SBS, she says the dangers of shaking are real.
"Shaking hurts babies. There's no doubt about that," said Dr. Jenny, an internationally known expert in child-abuse prevention and infant head trauma. "And there tends to be a triad of symptoms."

"It's not to say that every child that has those three things has been shaken - some of them have been hit, and there will be some rare diseases that need to be ruled out," she said.

"That's our job as professionals, to make sure that we consider all the options and make sure we come up with the right diagnosis," Dr. Jenny said.

Cases that may be the result of abuse are extremely difficult to judge, said Dr. Barr, who holds a Canada research chair in community child health. Victims can't talk, and in the vast majority of cases there are no witnesses.

"None of us who work in SBS or child abuse in general would say that you can just take the pathology and say: 'That's SBS,' " he said.

"You have to have the history, the circumstances and timing ... you'd never make it on the basis of the pathology alone."