Background
Child abuse is often misdiagnosed and under recognized by physicians and caregivers. Child abuse occurs in many forms and is best defined as purposeful infliction of physical or emotional harm, sexual exploitation, and/or neglect of basic needs (eg, nutrition, education, medical care). Child abuse is an important cause of death in children. Among child abuse fatalities, head injury is the leading cause of death in infancy.
Shaken baby syndrome (SBS) is of particular interest to the neurologist, as it affects the nervous system. Shaken baby syndrome may cause long-term sequelae in the developing nervous system, and the effects may even be lethal. See the image below.
In 1946, Caffey reported a series of patients with multiple fractures and chronic subdural hematoma, which fit the profile of what is now defined as shaken baby syndrome. [1] Kempe et al coined the term battered child syndrome. [2] In 1967, Gilkes and Mann first reported the funduscopic findings of battered babies. [3] In 1972, Caffey wrote about the syndrome of shaken infants. His report brought attention to this form of child abuse. [4]
The term "shaken baby syndrome" has been commonly used to describe symptoms consistent with shaking an infant, which produces bilateral retinal hemorrahge and diffuse brain injury. However, the term shaken impact syndrome is used for injuries that exceed those just from shaking and have evidence of blunt head trauma. "Abusive head trauma" is now the recommended term by the American Academy of Pediatrics. This term describes the type of injury rather than the mechanism of injury.
The American Academy of Pediatrics in 2009 recommended the use of the term "abusive head trauma," rather than shaken baby syndrome or non-accidental injury. [5]
Abusive head trauma (AHT) is a well-recognized brain injury associated with the direct application of force to an infant that results in physical injury to the brain and/or its contents. [6]
Pathophysiology
Anatomic features make infants especially prone to neurologic injury from excessive shaking or trauma. Infants have a large head compared with their body size, and the cervical paraspinal muscles are weak. (This accounts for head lag observed during the first month of life.) The infant brain has a higher water content than that of the adult brain, and it is incompletely myelinated. The subarachnoid spaces are also larger in infants than in adults, given the small size of their brains.
When the infant is shaken, movement of the immature brain in relation to the skull and the poor muscle tone in the neck cause the bridging vessels to tear, resulting in the classic finding of a subdural hematoma. Retinal hemorrhages are produced when venous congestion causes rupture of the retinal vasculature. Therefore, shaken baby syndrome is defined by subdural hemorrhage and retinal hemorrhage. One additional feature is occult fractures, particularly of ribs and long bone metaphyses.
The mechanism by which brain damage occurs is controversial. Traditionally, shearing forces from direct trauma were believed to cause axonal damage. Geddes et al suggested hypoxia-ischemia as the mechanism rather than axonal injury that is seen in older children and adults with lethal head trauma. [7, 8] They also thought that acceleration and deceleration forces may damage the neuraxis to cause apnea, with consequent ischemia and cerebral edema.
Biomechanical studies of infant trauma injuries have shown that the magnitude of angular deceleration is 50 times greater when the infant's head strikes a surface than when he or she is only shaken. This force is distinct from those of other accidental traumas that occur in infants. This evidence suggests that the term shaking-impact syndrome is more accurate than shaken baby syndrome.
Epidemiology
Frequency
Nationally in 2015, an estimated 1670 children died from abuse and neglect in the United States. Nearly 700,000 children are abused in the United States annually. An estimated 683,000 children (unique incidents) were victims of abuse and neglect in 2015, the most recent year for which there is national data. The youngest children were most vulnerable to maltreatment. Children in the first year of their life had the highest rate of victimization—24.2 per 1000 children in the national population of the same age. [9]
Mortality/Morbidity
Abuse and neglect account for 5–14% of all deaths of children. The youngest children were most vulnerable to maltreatment. Children in the first year of their life had the highest rate of victimization—24.2 per 1000 children nationwide. [9]
In Missouri in 2015, 35 deaths as a result of abuse or neglect were reported. [10] In Illinois in 2015, 77 child deaths as a result of abuse or neglect were reported. [11]
In children younger than 1 year, homicide is the leading cause of death. This is the only cause of death in children that is increasing in frequency. [12]
Sex
Boys are affected more often than girls.
The perpetrator is usually alone with the victim. Men are the abusers in 90% of cases. The abuser is usually the biologic father or, in some cases, the mother's boyfriend. The most common female attacker is a babysitter.
According to a Philadelphia-based study, 1 in 7 mothers who were abused as children admitted to using corporal punishment on their children. [13]
Age
In 2009, 3.3 million cases of child abuse and neglect were reported. Of these, 331,500 cases were substantiated. About 20.282% of the affected children were younger than 3 years, and 20.6% were younger than 1 year. [14] The typical abused child is younger than 6 months.
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CT scan shows a subdural hematoma.
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CT scan shows cerebral edema with loss of gray matter–white matter distinction.
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T1-weighted MRIs reveal bilateral chronic subdural hematomas as well as severe encephalomalacia involving the parietal, occipital, and temporal lobes.
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T1-weighted MRIs show chronic bilateral subdural hematomas.
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T2-weighted MRIs show encephalomalacia after shaken baby syndrome.
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Sagittal MRIs show chronic subdural hematoma.
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Funduscopic image shows intraretinal hemorrhages, subhyaloid hemorrhages, localized hemorrhagic choroid detachments, and thin retinal folds.
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Flair and T2 images reveal intrahemispheric bleeding.
