Delayed-onset subdural hematoma after mild head injury with negative initial brain imaging

Mild head injuries are commonly encountered in the neurosurgical field and emergency room (ER). The usual step is to discharge if the mental status of the patient is good and the initial brain computed tomography (CT) findings are normal. Here, we report a rare case of an 82-year-old male patient who developed delayed-onset bilateral subdural hematoma five weeks after a mild head injury. He was not on anticoagulant or antiplatelet therapy. The initial CT scan on the day of injury and magnetic resonance (MR) imaging performed seven days after the injury did not reveal any intracranial pathology or skull fracture. However, he presented with severe headaches and an unsteady ataxic gait five weeks later. Brain CT revealed bilateral subdural hematoma compressing the lateral ventricles with a midline shift to the right side. The possible pathophysiological mechanisms underlying this uncommon entity are discussed with a review of the relevant literature.