Clinical Presentation:
Subdural hematomas typically result from extensive head injury and may be seen in 30% of patients with severe closed head trauma. In younger patients, automobile accidents account for the extensive head injury whereas elders experience the injury from a fall. Rarely, subdural hematomas result from metastases or aneurysms. In this case, the hematoma was spontaneous due to the factor IX deficiency.
Pathology:
The subdural hematoma is caused by a stretching and tearing of cortical veins as a result of the rotational movement of the brain and is located between the dura and subarachnoid spaces.
Image Findings:
CT scans show acute subdural hematomas as, high density concave extracerebral mass with a variable thickness. Mass effect is commonly associated with significant hematomas. Chronic hematomas show low density and may have peripheral enhancement and subacute hematomas are isodense to the brain. If the lesions are bilateral and isodense, look at the gray-white matter interface. If the interface is "buckled inward" from the normal location, consider isodense subdurals.
MR scans show acute subdural hematomas as isointense on T1WI and hypointense on T2WI while subacute subdural hematomas show high intensity on T1WI and dark or bright on T2WI. As the chronic hematoma ages, it becomes isointense to CSF.
Differential Diagnosis:
Differential diagnosis includes epidural hematomas, which are confined by the cranial sutures and subdural empyema. Both the subdural empyema and chronic subdural hematoma enhance however, empyema is usually bright on diffusion weighted images.
Treatment:
Surgical evaluation of hematoma.