locations of the brain, then surgery is typically performed to clear the blood. If the size of the subdural is small, surgery may not be necessary, since the subdural blood will naturally be resorbed by the brain.
Another way that a subdural hemorrhage can occur is from a blow to the head or a direct impact. In this instance, it is known as a “contact subdural.” The mechanism for this to occur is often a fall onto a hard surface. Physics is brought into play here as well. The type of motion for a contact subdural is called a translational fall—from point A to point B in a straight line. When an infant or young child falls from an elevated surface and his or her head impacts a hard surface, a fracture may or may not occur. Beneath that fracture, a contact subdural may develop. The bleeding, especially in accidental falls, is typically epidural and necessitates immediate removal of the blood. Subdural bleeding in translational falls can be mass-occupying, meaning the hematoma expands and presses downward on the brain. Such bleeding needs surgical evacuation.
When an infant falls from an elevated surface down to a carpeted or hard floor, the chance of significant damage to the head is small. The greater the height (i.e. from a parent’s arms), the greater the potential for head injury.
If an infant was playing in a walker and happened to roll downstairs while he or she was still inside, then that would be a rotational event, where possible subdural bleeding occurs. There is the physical manifestation of acceleration/deceleration in rotational falls (similar to motor vehicle accidents) and bleeding in any rotational fall can be bilateral.
An interhemispheric subdural hemorrhage is very specific to shaken baby cases, as the blood actually cleaves between the hemispheres. Because of the whipping motion during shaking, blood goes right up the middle—between the left and right hemisphere of the brain. Interhemispheric bleeding is seen in the posterior (or back) section of the brain. In 1978, Dr. Robert A. Zimmerman first correlated interhemispheric subdurals with violent shaking.5 It is also not a good finding prognosis-wise, since subsequent CT scans of Zimmerman’s patients found that 100 percent had cerebral atrophy (brain shrinking).
EYE INJURIES
According to Dr. Alex Levin, “The overwhelming body of literature supports a conclusion that severe hemorrhagic retinopathy in otherwise previously well children without obvious history to the contrary (e.g. fatal head crush) suggests that the child has been submitted to abusive repetitive acceleration-deceleration trauma with or without head impact.”1
Retinal hemorrhages (RH) are the centerpiece of eye injuries that typically occur in SBS. Such hemorrhages cannot be seen with the naked eye. An ophthalmoscope is needed to view them, because the retina is situated at the very back of the eye, behind the globe. A normal retina includes an array of blood vessels and multilayered membranes. Retinal hemorrhages that result from violent shaking events can develop in front of the membranes (preretinal or subhyaloid), between the membranes (intraretinal) or below the membranes (subretinal).
The characteristics of retinal hemorrhages can be superficial and will manifest as splinter-type or flame-type hemorrhages or larger ones that are called dot or blot-type hemorrhages. Light retinal hemorrhages can disappear from anywhere within a few days to a few weeks. The larger hemorrhages can last several weeks. Retinal hemorrhage cannot be dated with any accuracy. When SBS retinal hemorrhages are present they are typically too numerous to count and extend from the back to the sides of the retina. This is the appearance of retinal patterns of SBS. On direct observation by an ophthalmologist or via a retinal camera, SBS retinal hemorrhages have been called centrifugal—as though blood has been splattered across the entire retina.
The majority of retinal hemorrhages in shaken children are bilateral (both sides effected). One eye may have more hemorrhages than the other; having an equal number of hemorrhages in both eyes is not needed to satisfy a diagnosis of SBS.
The posterior pole of the retina is stationed at the very back, in the area where the optic nerve leads to the brain. Retinal hemorrhages in SBS commonly extend throughout the entire retina, beginning at the posterior pole and going out to the periphery (the edge of the retina). Accidental falls may produce a few retinal hemorrhages. These do not spread out, are few in number and are very light in size and shape. They are also confined to the posterior pole.
Studies have shown that the mechanism for producing hemorrhages in the retina comes from a tractional pull on the eye globe during a shaking event. The globe of the eye pulls back and forth on the retina, thus producing extensive bleeding within the retina, as well as possibly other damage.
It is believed that approximately 80 to 85 percent of infants and children who are shaken have diffuse retinal hemorrhages. In lethal cases the retinal hemorrhages are typically more extensive. Some children who are severely shaken may not have retinal hemorrhages or the hemorrhages are few and are limited to the posterior pole.
Retinal hemorrhages can appear in other types of trauma (such as birth injuries and motor vehicle accidents) or disease (blood disorders, leukemia, meningitis, etc.). But the types of retinal hemorrhages that are seen in other situations are very different from the ones seen in SBS. They are fewer in number and confined to the posterior pole of the retina. This is important to note, especially when perpetrators of shaking incidents try to explain away infant injuries as “accidental,” such as a fall from a small height. The more violent the impact on the child, the more numerous the diffuse retinal hemorrhages.
When retinal hemorrhages are diagnosed, the discovery should be a part of a larger investigation of an abusive act. Such a diagnosis should not be the basis for an immediate judgment call of abuse. Other conditions need to be considered, laboratory testing performed and medical history checked within the child’s family.
Another ocular injury that is highly specific for SBS is optic nerve sheath hemorrhage. The optic nerve extends from the brain to the eye globe. It transmits visual messages from the retina to the brain, where it is converted into meaningful information. The optic nerve is the cornerstone of human sight. To protect it, the nerve is surrounded by a membranous sheath. When bleeding underneath the sheath is diagnosed in infants and children who are being assessed for abuse, the finding is highly suggestive of a shaking case.
Repetitive acceleration/deceleration injury can directly affect the optic nerve and may ultimately cause optic nerve atrophy, which leads to permanent blindness. One reason why optic nerve sheath hemorrhage is so unique in SBS findings is the lack of correlation to short falls. There are no documented cases in the medical literature of optic nerve sheath hemorrhage that connect it to short-distance falls. So when a baby is diagnosed with this particular ocular finding, or if it is noted on an autopsy, it then becomes problematic for a perpetrator’s defense if he or she is using the excuse that the baby “fell.”
There are three other optic injuries that correlate directly with severe shaking: retinoschisis, retinal folds and vitreous hemorrhages. These are consequences that are seen in so few other conditions in childhood that they are a clear association with abuse.
RETINOSCHISIS AND RETINAL FOLDS
What are retinoschisis and retinal folds? During shaking events, it has been previously noted that tractional pulling on the eye globe is thought to be the mechanism for causing retinal hemorrhages. That same pulling or tugging causes a splitting of the retina. This separation (or schisis) is a result of the retinal traction that severe shaking brings about. A retinal fold is caused by the same means, but instead of splitting, the retina folds onto itself. Though severe, injuries such as these can be surgically corrected but some infants and children can be permanently scarred with
