A syndrome of neurologic and other injuries, of variable presentation, induced by the violent shaking of an infant.
SBS is the leading cause of death and of long-term disability and permanent damage in physically abused infants and children. Vigorous shaking of an infant, with or without direct violence to the head, can result in spinal cord injury or intracranial bleeding, with irreversible brain damage, blindness, hearing loss, seizures, learning disabilities, paralysis, or death. SBS occurs most often before the age of 1 and seldom after age 2. Infants under 6 months are particularly vulnerable because of their disproportionately heavy heads, weak neck muscles, and thin skulls. The higher water content of the infant brain and its incomplete myelination render it more compressible during a shaking episode and more vulnerable to contusion and vascular injury with subdural or diffuse subarachnoid hemorrhages. Shearing of retinal blood vessels (uncommon in other types of head injury) can lead to intraocular hemorrhage, often bilateral. Death usually results from steadily increasing intracranial pressure due to subdural hemorrhage and cerebral edema. About 1,000 babies are hospitalized annually in the U.S. with this diagnosis. About 25% of them die and more than 50% of the survivors suffer irreversible residual neurologic or visual impairment. Long-term studies show that 25% of survivors initially considered symptom-free eventually display severe disorders of development. Men are more likely than women to inflict injury by shaking, as are people with a history of depression, anxiety, or substance abuse. Other risk factors are poor prenatal care, low family income, close child spacing, disappointment in the gender of the infant, and a family history of abuse or neglect. Boys are more likely than girls to be victims, and twins are at higher risk than singletons. Very-low-birth-weight and premature infants and those with disabilities or chronic illnesses are also at greater risk. Most shaking occurs as an impulsive response of the caregiver to a child's persistent crying. In the typical incident, no one is present but the caregiver and the victim. There may be a prior history of abuse or evidence of previous injury. The perpetrator may invent a story of accidental injury to explain the findings. Presenting signs of SBS vary widely, from a flulike condition, poor feeding, irritability, or lethargy to vomiting, respiratory arrest, seizures, or coma. The classical triad of subdural hematoma, cerebral edema, and retinal or subhyaloid hemorrhage is often absent. Finger marks may be found on the chest wall or around the shoulders, but typically there are no external signs of injury. One half of patients with subdural hematoma have no skull fracture. CT without intravenous contrast may show subarachnoid hemorrhages, mass effect, and subtle skull fractures missed by plain radiography. MRI and lumbar puncture may also help to refine or confirm the clinical diagnosis. Prevention of SBS requires education of parents and others entrusted with the care of small children as to the grave danger of shaking a baby. New parents should be informed that a normal infant cries a total of 1.5–3 hours each day and that shaking is never an appropriate response. Alternative ways of coping with the stress of a crying baby need to be planned. Parents must also exercise caution in selecting babysitters, day-care centers, or child-care agencies. All caregivers should be enjoined never to touch a child in anger. Health care professionals must be alert for subtle signs of SBS and other forms of child abuse.
Reference: Stedman's Medical Dictionary