How has medical understanding of ‘shaken baby syndrome’ evolved?

Many health groups no longer use the term shaken baby syndrome – the Public Health Agency of Canada, for example, says traumatic head injury due to child maltreatment (THI-CM) better reflects the current language used by health professionals.

Here’s how the medical evidence has evolved in understanding what was previously called shaken baby syndrome.

WHAT IS SHAKEN BABY SYNDROME?

The term is considered outdated, but refers to head and brain injuries that result from violently shaking an infant.

It was coined in the 1970s to describe infant abuse cases in which there was internal brain and retinal bleeding, but no external signs of head trauma.

In 2011, Health Canada, along with a number of national agencies including the Canadian Paediatric Society, described injuries that characterize SBS as bleeding in and around the brain, in the retina, and rib fractures at the ends of the long bones.

“A baby’s demands, especially crying, can become the trigger for a frustrated parent or caregiver to shake a child,” a statement from Health Canada at the time said.

But in 2008, a committee was established in Ontario after a public inquiry found major errors in the work of Dr. Charles Smith, who conducted more than 1,000 child autopsies during his tenure as the head forensic pathologist at the Hospital for Sick Children in Toronto.

The committee was asked to review shaken-baby deaths dating back to the 1980s “in light of the evolving science,” which questioned the validity of these diagnoses and pointed to other potential causes of death. Joeseph’s death was among them, and eventually examined by an international panel of medical experts.

The panel determined there was uncertainty regarding the cause of Joeseph’s death and the timing of his injuries. His head injuries had been mischaracterized as bruising when experts said they were in fact infarcts, or strokes, and it wasn’t clear whether they had caused the boy’s death, the panel found.

EVOLVING TERMINOLOGY

The Public Health Agency of Canada released a joint statement with the Canadian Paediatric Society in 2020 revising its 2001 terminology to “reflect developments in knowledge, understanding and practice within and between sectors.”

In it, the recommended terminology of shaken baby syndrome changed to traumatic head injury due to child maltreatment (THI-CM). A similar term, abusive head trauma, is used in the United States.

Traumatic head injuries due to child maltreatment are “relatively uncommon” in Canada and account for a small proportion of cases involving child abuse, neglect and exposure to intimate partner violence. However, morbidity and mortality are significant, the PHAC statement said.

“The term, THI-CM, is believed to reflect the current language used by health professionals (traumatic head injury) and aids to separate the diagnosis (traumatic head injury) from opinion on the cause of injury (child maltreatment).”

The federal agency said THI-CM should not be communicated as a definitive diagnosis based solely on initial medical information.

“While some types of injuries have a higher likelihood of being the result of maltreatment, no one medical finding or constellation of findings is exclusively caused by THI-CM.”

DIFFERENTIAL DIAGNOSIS

Dr. Guillaume Sébire, a pediatric neurologist in Montreal who has served as a medical expert in about 100 legal cases in Canada, France and the United States, said many of the medical outcomes associated with THI-CM can be a result of rare diseases, such as a brain malformation, blood clotting disorder, or a non-traumatic hemorrhage.

Though it is rare, Sébire said in his 40 years as a neurologist he’s also seen babies who have suffered from a brain hemorrhage after a short fall, or severe viral or bacterial infection.

Sébire said “differential diagnosis,” in which a doctor distinguishes conditions that have overlapping symptoms, was not initially considered with many shaken-baby cases.

“There is a big grey zone,” Sébire said

Gerard Pals, director of a genetic testing lab in Amsterdam, who has served as an expert witness in Canadian cases, said medical imaging advancements, such as CT scan 3D imaging and MRIs, have made it possible to take a closer look at causes of brain damage.

As an example, he said imaging can help identify if a brain bleed is a result of a brittle bone disease called osteogenesis imperfecta. A lumbar puncture can also help to show that swelling of the brain is due to an infection like meningitis, rather than abuse.

“I have had at least 15 cases where I see this,” Pals, who has examined 150 cases in 10 countries, said about osteogenesis imperfecta.

“And in most of those cases, the extra sutures in the skull have been misdiagnosed by the accusing doctors as fractures, or they have not been mentioned at all and didn’t realize this could have caused intracranial bleeding.”

HOW TO ASSESS

Some health groups acknowledge that while there is risk in ignoring a differential diagnosis, there is also a risk in overlooking or delaying the identification of head trauma caused by abuse.

They say this could happen because of overlapping symptoms with other illnesses, and the absence or subtle signs of external injuries.

The Canadian Paediatric Society addresses this in its latest guidance for health providers assessing suspected cases.

CPS recommends health providers be on alert for “red flags,” such as an unreasonable delay in seeking medical care, or an injury that does not align with the child’s development.

It’s also critical for medical providers to take a comprehensive history, including information on the infant’s birth, development and circumstances of the injury, the group said in a document on medical assessment of suspected THI-CM.

“Cases of suspected THI-CM should be approached with an open mind, awareness of possible bias, and compassion for the child and family,” CPS said.

With files from Paola Loriggio in Toronto.

This report by The Canadian Press was first published Oct. 1, 2026.

Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.

Hannah Alberga, The Canadian Press

by The Canadian Press

How has medical understanding of ‘shaken baby syndrome’ evolved?

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