Does hypernatremia cause subdural hematoma in children?: two case reports and a meta-analysis of the literature.

Hypernatremia has been causally linked with subdural hematoma (SDH), but more recently this has been called into question. Conversely, there is a well-established link between SDH and injury. We wish to examine the evidence base that hypernatremia in infants and young children causes SDH.We present 2 cases of children with severe hypernatremia whose intracranial contents were assessed by imaging in the first case and postmortem examination in the second. Neither demonstrated SDH. The first case was important as the hypernatremia was iatrogenic occurring in a controlled hospital environment.We also searched the literature from 1950 to 2007, collecting data on all reported cases of hypernatremia in children younger than 7 years whose intracranial contents were examined by imaging, surgery, and/or postmortem examination. Of 124 cases reported in 31 articles, 112 cases developed hypernatremia in the community, and 12 in the hospital. Subdural hematoma was demonstrated in 7 cases, all of which had developed hypernatremia in the community under circumstances that would make it difficult to exclude nonaccidental injury. None of the 12 cases that developed hypernatremia in a controlled hospital environment had SDH.The evidence base supporting the hypothesis that hypernatremia causes SDH is poor, depending on isolated reports with uncertain histories.