SBS 101
Subdurals
Retinal Hemorrhages
Fractures
Anatomy of an Autopsy
Neuro-Anatomy 101
Biomechanics 101
SBS Myths
Alternate Explanations
Annotated Bibliography
Glossary
Subdural hematomas and retinal hemorrhages can only be caused by shaking even in the absence of other injuries.
Truth:
Many things produce subdural hematomas and retinal hemorrhages. Biomechanical research and human case material has disproven the theory that shaking alone can cause subdural hematomas and retinal hemorrhages, without causing other injuries (neck damage, rib fractures, etc.)
In many cases with allegations of nonaccidental trauma, the child has a subdural hematoma and the requisite retinal hemorrhages without any appreciable damage to the outside of the head. In these cases, the child often lacks an impact site (contusions or fractures). This pattern of injuries can be diagnostically puzzling for physicians. State's experts have traditionally regarded these as "Pure Shaking" cases. If the child has an old subdural hematoma or a preexisting injury, then shaking alone is likely enough force to create a rebleed or spontaneous bleed, but the question remains whether shaking alone, of a previously healthy infant, can cause SDH and retinal hemorrhages, and if so, how does that kind of force compare to a short fall?
Prosecution experts testify that shaking alone of an otherwise healthy infant, can cause the symptoms seen in these cases, but that the impact of a short fall cannot. In 1987, Duhaime, Genarelli, Thibault, Bruce, Marguiles and Wiser (1) conducted an experiment where an accelerometer was placed on a model of an infant. Triathletes experimented with shaking versus impact injuries. The study found that angular accelerations for shaking was less than that for impact by a factor of 50. Duhaime et al. determined that shaking alone of an otherwise healthy infant could not cause the constellation of injuries generally associated with SBS. They determined that impact was needed. This study has been replicated several times with similar results.
A recent study by Ommaya, Goldsmith and Thibault showed that impact loading creates a force 50-100 times greater than what can be created by human shaking. The article shows deformation of an infant's skull makes him or her much more vulnerable to head injuries than adults and that a short fall can adequately produce the requisite force to create a subdural hematoma.
Citations
1.
Duhaime, A.C., Gennarelli, T., Tibualt, L.E. Bruce, D.A., Margulies, S.S.,
and Wiser R. (1987). The Shaken Baby Syndrome: A clinical, pathological,
and biomechanical study. Journal of Neurosurgery 66:409-415.
2. Ommaya, Goldsmith, and Thibault. Biomechanics and neuropathology
of adult and pediatric head injury. British Journal of Neurosurgery 2002;16(3):
220-242.