A subdural hematoma is a collection of blood that forms between the outer layer of the brain, called the dura mater, and the brain itself. This condition often occurs after a head injury, where blood vessels are torn, leading to bleeding in the space. Symptoms can include headaches, confusion, and changes in behavior, which may develop gradually. Diagnosis typically involves imaging tests like a CT scan or MRI to visualize the bleeding. Treatment may require monitoring or surgical intervention to remove the accumulated blood, especially if it causes pressure on the brain. Early detection is crucial for better outcomes.