The frequency of child abuse and unintentional injury as a cause of infant and toddler subdural hedmorrhage (SDH) was determined by a prospective study of 66 cases admitted to Harborview Medical Center, a level I pediatric trauma center, and the Children’s Hospital and Regional Medical Tertiary Care Center, Seattle, WA, from March 1995 through December 1998. The cause of SDH was confirmed abuse in 39 (59%), unintentional injury (motor vehicle accident or major trauma) in 15 (23%), and indeterminate in 12 (18%). The mean age at injury for abuse and accidental cases was 8.7 and 19.1 months, respectively. The presenting history for abuse injury was a minor fall or unknown reason in 33 (84%) of 39 patients, while that of unintentional injury was a motor vehicle accident or other major trauma in all cases. Chronic SDH or mixed acute and chronic SDH occurred only in abused children (17 [44%]), and in those with indeterminate injuries (8 [67%]). Long bone and/or rib fractures were present in 20 (51%) of abuse cases, and in only 1 of unintentional, accidental head injury cases. Retinal hemorrhages were diagnosed in 28 (72%) of abuse cases, none of 7 indeterminate cases, and in 1 of 3 accidental cases examined. The authors conclude that any infant or toddler with SDH or subdural effusion, in the absence of motor vehicle or other major trauma, should be checked for child abuse. 
COMMENT. Unintentional, accidental trauma accounts for almost one quarter of cases of subdural hemorrhage (SDH) in infants and toddlers, and 60% are related to a motor vehicle accident. Falls are an infrequent cause, occurring in only 4%, and always from heights greater than 10 feet on to hard surfaces. When obvious accidental cause is ruled out, abuse is most likely in 76% of cases. Associated reasons to suspect abuse include a younger age group, absence of a significant history of trauma, evidence of chronic SDH, retinal hemorrhages, long bone or rib fractures, and multiple injuries. An infant or young child presenting with a history of head injury following a minor fall and signs of bruising or other evidence of trauma should receive a head CT scan and be evaluated for child abuse.