Sunday, 5 September 2010

SBS: A Clinical, Pathological, And Biomechanical Study Of Shaken Baby Syndrome

September 3, 2010
Division of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania
Because a history of shaking is often lacking in the so-called “shaken baby syndrome,” diagnosis is usually based on a constellation of clinical and radiographic findings. Forty-eight cases of infants and young children with this diagnosis seen between 1978 and 1985 at the Children's Hospital of Philadelphia were reviewed. All patients had a presenting history thought to be suspicious for child abuse, and either retinal hemorrhages with subdural or subarachnoid hemorrhages or a computerized tomography scan showing subdural or subarachnoid hemorrhages with interhemispheric blood. The physical examination and presence of associated trauma were analyzed; autopsy findings for the 13 fatalities were reviewed. All fatal cases had signs of blunt impact to the head, although in more than half of them these findings were noted only at autopsy. All deaths were associated with uncontrollably increased intracranial pressure.
Models of 1-month-old infants with various neck and skull parameters were instrumented with accelerometers and shaken and impacted against padded or unpadded surfaces. Angular accelerations for shakes were smaller than those for impacts by a factor of 50. All shakes fell below injury thresholds established for subhuman primates scaled for the same brain mass, while impacts spanned concussion, subdural hematoma, and diffuse axonal injury ranges. It was concluded that severe head injuries commonly diagnosed as shaking injuries require impact to occur and that shaking alone in an otherwise normal baby is unlikely to cause the shaken baby syndrome.
The term “whiplash shaken baby syndrome” was coined by Caffey
3 to describe a clinicopathological entity occurring in infants characterized by retinal hemorrhages, subdural and/or subarachnoid hemorrhages, and minimal or absent signs of external trauma. Because a nursemaid admitted that she had held several such children by the arms or trunk and shaken them, the mechanism of injury was presumed to be a whiplash-type motion of the head, resulting in tearing of the bridging veins. Such an injury was believed to be frequently associated with fatalities in infantile child abuse and has been postulated as a cause of developmental delay in survivors.4,15
While the term “shaken baby syndrome” has become well entrenched in the literature of child abuse, it is characteristic of the syndrome that a history of shaking in such cases is usually lacking.12 Shaking is often assumed, therefore, on the basis of a constellation of clinical findings and on the computerized tomography (CT) picture of subarachnoid and subdural hematomas, particularly in the posterior interhemispheric fissure.17 Because of the ambiguous circumstances of such injuries, medicolegal questions are particularly troublesome, and the neurosurgeon is often consulted to give an opinion as to whether the findings are consistent with child abuse or accidental injury.
This paper reviews all cases of the shaken baby syndrome seen at the Children's Hospital of Philadelphia (CHOP) between January, 1978, and March, 1985. To better study the mechanism of injury, autopsy results in all fatal cases were reviewed, and the biomechanics of this injury were studied in a series of infant models. Based on these observations, we believe that shaking alone does not produce the shaken baby syndrome.

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