Traumatic acute convexity interdural hematoma: a case report and literature review

Interdural hematoma (IDH) is an extremely rare hemorrhage between the outer periosteal dura mater and the inner meningeal dura mater. There are 8 cases of convexity IDH reported previously but none of them were acute post traumatic one. We report the case of a patient with an initial diagnosis of acute epidural hematoma (EDH) that was eventually revealed to be an acute convexity IDH.

A 57-year-old man presented to the emergency department with a complaint of falling from 2 meters. Imaging findings revealed an expanding intracranial hematoma with a linear skull fracture extending to sagittal suture, which was mistaken as an EDH. Emergent surgical evacuation was performed; the hematoma was lodged between two dural layers.

This is the first case of acute convexity IDH following trauma that has been reported. In chronic and sub-acute hematomas MRI scans could be very useful, but in acute cases under emergent circumstances, CT scan cannot make a proper differentiation between an EDH and IDH. IDH should be considered during craniotomy when extradural findings do not explain the CT scan findings. This case showed a linear skull fracture expanding to the sagittal suture, and this can be a possible explanation for IDH formation. Surgical evacuation of the hematoma without inner nor outer layer resection and leaving the outer layer open, to connect the interdural space to epidural space was first described in this report.