Analysis of perpetrator admissions to inflicted traumatic brain injury in children. 
Scientific and courtroom debate exists regarding the timing of onset of symptoms and the mechanism of injury in infants and children with inflicted traumatic brain injury (ITBI).  To determine the time interval between ITBI and the onset of symptoms and to explore the mechanism of ITBI.  Retrospective review of all cases of pediatric ITBI admitted between January 1, 1981, and July 31, 2001, to a large academic medical center and cases admitted to 2 additional academic institutions between January 1, 1996, and August 31, 2000, and January 1, 2001, and July 31, 2001, comparing 81 cases of ITBI in which perpetrators admitted to abuse with 90 cases in which no abuse admission was made.  The patients with perpetrator admissions to ITBI consisted of 53 boys (65%) and 28 girls (35%).  Their ages ranged from 2 weeks to 52 months.  Characteristics associated with perpetrator admissions to ITBI in children.  Shaking was the most common mechanism of injury among all cases with perpetrator admissions: 55 (68%) of the 81 perpetrators admitted to shaking the children.  Impact was not described in 44 (54%) of the 81 cases.  In cases in which only impact was described, 60% (12/20) of the children showed skull or scalp injury, compared with 12% (4/32) with skull or scalp injury in the shake only group.  In 52 (91%) of 57 cases in which the time to the onset of symptoms was described, symptoms appeared immediately after the abuse.  In 5 cases (9%), the timing of symptoms was less clear, but they occurred within 24 hours.  None of the children were described as behaving normally after the event.  The symptoms of inflicted head injury in children are immediate.  Most perpetrators admitted to shaking without impact.  These data, combined with the relative lack of skull and scalp injury, suggest that shaking alone can produce the symptoms seen in children with ITBI.