Shaken baby syndrome (SBS) is a form of child abuse resulting in an inflicted traumatic brain injury (TBI) thought to be secondary to a sudden deceleration which results in trauma to the brain of a young child. This sudden deceleration can occur when the child is violently shaken and the brain strikes the inner surface of the skull or when there is an impact where the head strikes or is struck by an object, such as a mattress, a fist, or a wall.
- Historical Perspective
- Social Factors
- Pathophysiology of Injuries
- Evaluation and Treatment
Shaken baby syndrome (SBS) is a form of child abuse resulting in an inflicted traumatic brain injury (TBI) thought to be secondary to a sudden deceleration which results in trauma to the brain of a young child. This sudden deceleration can occur when the child is violently shaken and the brain strikes the inner surface of the skull or when there is an impact where the head strikes or is struck by an object, such as a mattress, a fist, or a wall. The injuries which characterize the syndrome include some but not always all of the following: bleeding in and around the brain, bleeding in the retina of the eye, and fractures of the ribs and ends of the long bones. When there is an impact involved, additional injuries may include bruising to the body, often to the face and scalp, and skull fractures. In severely battered children, injury to abdominal organs, pancreas, liver, or intestines may occur, as well as mid-shaft fractures of the long bones and fractures of the spine.
As early as 1946, John Caffey, a pioneering pediatric radiologist in New York, noted the associated injuries of long bone fractures and hemorrhages on the surface of the brain (subdural hematomas) in infants. He was puzzled by the lack of history of trauma to these infants and described the causal mechanism as ‘‘obscure.’’ In only one case out of the six he reported did he describe the infant as being ‘‘unwanted’’ by the parents, raising the question of ‘‘intentional ill treatment.’’ As aware of child abuse as doctors and researchers are today, this seems an almost unbelievable conclusion; however, it is important to note that Henry Kempe, a pediatrician in Denver, Colorado, did not publish the landmark article on battered child syndrome until 1962. This was the first time that the concept of children receiving nonaccidental injuries at the hands of their parents was actually spelled out in the medical literature.
Further work by A. Norman Gulthkelch, a British neurosurgeon, identified whiplash shaking forces as a cause of subdural hematomas. Caffey later postulated that children who are violently shaken can develop the classic SBS triad of long bone fractures, subdural hematomas, and hemorrhages in the back of the eyes (retinal hemorrhages). More recently, the term shaken impact syndrome has been coined, as research has demonstrated that many victims of SBS also receive blows to the head that may be identifiable only at autopsy. Tina Duhaime, a pediatric neurosurgeon working with biomedical engineers at Children’s Hospital of Philadelphia, developed mechanical models to study SBS. The conclusion of that work was that shaking alone cannot generate forces high enough to cause the injuries seen in SBS. This concept remains controversial, as many pediatricians experienced in the diagnosis and management of SBS have had parents confess to violent shaking of their crying infants until the infants went limp and were quiet. This event was followed in many cases by death or evidence of serious brain injury in the infant. James Peinkofer has written a detailed and fascinating history of the gradual recognition and acceptance of SBS by the medical community.
By the middle 1980s Elaine Billmire and colleagues had established child abuse as the leading cause of serious trauma and death due to head trauma in infants. The majority of inflicted traumatic brain injury occurs in children younger than two years of age, with a mean age of four to eight months at the time of injury. Male children are more often victims than females. A recent population-based study in the United States has revealed an incidence of inflicted TBI of 17 cases per 100,000 person-years in children less than two years of age. The mortality rate for SBS ranges from 12 to 30 percent of those victimized. Fewer than 15 percent of the victims of SBS will have normal developmental outcomes. The remainder have moderate to severe problems which may include seizure disorder, cerebral palsy, loss of vision, cognitive impairment, emotional volatility, and living in a permanent vegetative state.
Several characteristics of infants are proposed as reasons they are the likely victims of SBS. Prolonged crying often triggers the abuse, and young infants cry a lot, up to three hours per day. They are small enough to be picked up and shaken and thrown by an adult. There are anatomical features that make them vulnerable: Their heads are large in proportion to their body size, they have relatively weak neck muscles, and the base of the skull is flatter than that of an adult, allowing the brain to move around more in the cranial cavity in response to shaking or direct blows as the head moves back and forth in a whiplash type movement.
Suzanne Starling has looked at characteristics of perpetrators of SBS. Male caretakers, including biologic fathers, stepfathers, and mothers’ boyfriends were perpetrators in 68 percent of the cases she studied. The preponderance of male caretakers as perpetrators of SBS has been confirmed in other studies.
Poverty, young maternal age, unmarried status at the time of the birth of the child, and low educational level of the mother have all been associated with increased risk of inflicting traumatic brain injury. Multiple births, premature births, and parents active in the military are other well-known risk factors for SBS.
Pathophysiology of Injuries
There are tiny blood vessels that course from the brain to the membranes overlying the brain and to a large vein coursing through the cranial cavity. With violent shaking or with a blow, the brain undergoes whiplash and rotational forces shearing through the blood vessels and at times through the brain tissue itself. There are membranes covering the brain. There is an outer dural membrane and an arachnoid membrane which is more tightly adherent to the brain. The resulting collection of blood pooling over the brain and under the dural membrane is called a subdural hematoma. Bleeding under the arachnoid membrane is called a subarachnoid hemorrhage. The brain itself may be bruised or sheared, resulting in damage to nerve cells. Subsequent brain swelling in response to injury can cause additional damage due to loss of normal blood circulation and lack of oxygen to brain tissues. The spinal cord may also experience bruising or hemorrhage secondary to whiplash forces.
Fractures of the skull result from blows to the head. Rib fractures are thought to be most likely secondary to compression as the adult hands circle the rib cage squeezing the child during the shaking maneuver. Fractures of the ends of the long bones, called metaphyseal fractures, occur from violent flailing or jerking of the limbs while the child is being shaken. The pathophysiology of retinal hemorrhages is not known, but actual separation of the layers of the retina during shaking has been proposed as the mechanism of this finding. Seventy-five percent or more of SBS victims will have hemorrhages within the layers of the retina or in the vitreous humor (the fluid within the globe of the eye). At times the retinal layers can be split and large collections of blood may layer out. This is called retinoschisis.
It is clear that the injuries of SBS are the result of violent acts and if witnessed by a layperson could not be seen as normal handling of a child and would be recognized as dangerous to the infant. Signs and Symptoms of Shaken Baby Syndrome Children with mild injury due to SBS may experience increased sleepiness, fussiness, and decreased interest in feeding. With more severe injury, the child may present with vomiting, seizures, apnea (cessation of breathing), and/or an altered level of consciousness. In many cases, infants are brought to emergency facilities when families call 911 because their infants have stopped breathing or have had seizures. Mild symptoms can be confused with a viral illness, and due to parents not providing accurate histories, as well as the young ages of the infants, the correct diagnosis may be missed. Carole Jenny has studied this phenomenon and has reported that missing the diagnosis often results in further injury, medical complications, and even death in these cases. Bruising of the face or head of an infant may be a clue to head injury and should call for further medical investigation.
Evaluation and Treatment
The development of computerized axial tomography (CAT scan) and magnetic resonance imaging (MRI scan) of the head have enabled physicians to more easily diagnose TBI in young children. Additional diagnostic techniques for SBS include a full skeletal survey, which is an x-ray of all the bones in the child’s body, looking for fractures. Small, hairline fractures may not be easily seen, and other studies such as imaging with a small amount of radioactive material that localizes in bone (bone scan) or repeat skeletal survey in two weeks may be helpful. Once fractures are healing, they may be more visible on an x-ray. An eye exam by an eye specialist after dilation of the pupils to look for retinal hemorrhages is essential in a suspected SBS case. Additional laboratory testing is often necessary because of the life-threatening nature of the injuries and in order to eliminate other possible causes of the clinical findings in the child. If a spinal tap is performed to look for infection, bloody spinal fluid will be found if a subarachnoid hemorrhage is present. In cases of subdural hematoma, the baby may be anemic from loss of blood into the subdural space. Both bloody spinal fluid and anemia can be clues which help the physician establish a correct diagnosis of SBS.
A detailed discussion of treatment is beyond the scope of this research paper, but each injury to the brain, eyes, skin, and skeleton is managed individually. In cases where SBS is suspected, appropriate reporting to the local department of social services and law enforcement is mandated by law. Willingness of the doctor to testify in both juvenile and criminal courts is an important part of the management of SBS. It will be the decision of social services and the courts to determine whether the child has been abused and to ensure a safe environment after the child’s discharge from the hospital. Law enforcement, district attorneys, and criminal courts are responsible for determining who the perpetrator is in an SBS case and what the punishment will be if there is a criminal prosecution and conviction.
Victims of SBS will need very careful follow-up for medical and developmental assessments. Appropriate services need to be provided to enable the child to reach full potential after injury.
The financial cost of SBS has been difficult to determine. Several research studies have shown that children with inflicted traumatic brain injury who survive have longer hospital stays and poorer outcomes than victims of accidental traumatic brain injury. In 1997, Jose Irazuzta and colleagues estimated charges for inflicted traumatic brain injury at an average of $35,641 per case seen in a pediatric intensive care unit. However, children left with severe disabilities may incur millions of dollars in medical costs over their lifetimes, and that cost is often borne by public programs instead of private insurance. These severe disabilities and accompanying financial costs, as well as loss of life, make attempts at prevention of SBS very desirable.
SBS prevention programs have been established in many communities. The idea behind these efforts is that if caretakers have knowledge of how dangerous it is to shake a baby, they would not do it, even in anger. Other experts working in the field believe that adults who shake infants are so angry and out of control that educational efforts may not be successful in many cases. There are other prevention efforts directed toward educating parents about how to understand and manage crying in a young infant, since crying is often a trigger of the shaking. In general, providing support to young families, particularly through home visitation by nurses, has been successful in preventing all types of child abuse.
- Alexander, R. C., C. J. Levitt, and W. L. Smith. ‘‘Abusive Head Trauma.’’ In Child Abuse Medical Diagnosis and Management, edited by Robert M. Reece and Stephen Ludwig. Philadelphia: Lippincott, Williams, and Wilkins, 2001, pp. 47–80.
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- Caffey, J. ‘‘Multiple Fractures in the Long Bones of Infants Suffering from Chronic Subdural Hematoma.’’ American Journal of Roentgenology 56, no. 2 (1946): 163–173.
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