Snapshot A 76-year-old man presents to the emergency department with increasing somnolence and lethargy. His symptoms developed on the day of admission. His symptoms are associated with a headache with mild nausea but no vomiting. He tripped over a carpet and hit his head on the floor. A head CT without contrast demonstrates a crescent-shaped hyperdensity that crosses the suture lines. Introduction Definition venous bleeding in the potential space between the brain parenchyma Epidemiology Risk factors cerebral atrophy, which can be seen in aging chronic alcohol use previous tramautic brain injury anti-thrombotic medication use Pathogenesis Head injury results in tearing of the bridging veins Presentation Symptoms/physical exam acute subdural hematoma coma symptoms of increased intracranial pressure if the bleeding occurs in the posterior fossa headache nausea and vomiting cranial nerve palsies chronic subdural hematoma headache cognitive impairment somnolence Imaging CT head without contrast indication imaging study of choice in the evaluation of a subdural hematoma findings crescent-shaped and concave hyperdensity that can extend across suture line Differential Epidural hematoma differentiating factors lens-shaped and biconvex hyperdensity that does not cross the suture lines Subarachnoid hemorrhage differentiating factors thunderclap headache hyperdensity in the subarachnoid space on CT head without contrast Treatment Operative surgical evacuation indication treatment of choice in symptomatic (e.g., cranial nerve palsies, midline shift, and symptoms of increased intracranial pressure) subdural hematomas Complications Brain herniation Seizures Hydrocephalus