Why do children vomit after minor head injury?

OBJECTIVE To determine factors associated with vomiting after minor head injury in a paediatric population with the intention of defining the role of vomiting in management decisions. METHODS A prospective study of all patients presenting with minor head injury to the Royal Hospital for Sick Children, Edinburgh, between 1 May and 30 June 1997. Information regarding basic demographics, features of the head injury and past and family history was noted on a proforma. This included mechanism of injury, site of impact, presence or absence of scalp haematoma, skull fracture or brain injury and intrinsic factors such as age, family history of migraine and a personal history of migraine, its childhood variants and associated conditions. The relation between vomiting and these features was analysed using chi2 and Fisher's exact tests. RESULTS 563 children aged from birth to 13 years presented with minor head injury. Complete data were obtained on 463 patients. Some 15.8% vomited after minor head injury. Comparing vomiters with non-vomiters the only associated factors that could be identified were a past history of recurrent vomiting or motion sickness (p= 0.0035, p=0.036 respectively). CONCLUSIONS Vomiting after minor head injury seems to be related to individual intrinsic factors rather than specific features of the head injury and its role in management decisions needs to be explored further.