Scintigraphic demonstration of intracranial communication between arachnoid cyst and associated subdural hematoma.

An arachnoid cyst found to have a communication to an associated subdural hematoma was demonstrated with the Tc-99m DTPA brain scintigraphy. Although arachnoid cysts are known to be silent, when a patient with an arachnoid cyst develops signs of increased intracranial pressure or neurological deficits, the presence of a complication, including subdural hematoma, intracystic hemorrhage or subdural hygroma, is highly suspected. In the present case, the patient with an arachnoid cyst had a subdural hematoma following minor head injury. Tc-99m DTPA brain scintigraphy showed abnormal accumulation of the tracer not only in the hematoma but in the arachnoid cyst. This observation suggested communication of the two lesions, which was confirmed at surgery.