Spontaneous Subdural Hematoma and Intracystic Hemorrhage in an Arachnoid Cyst

Abstract

We report the case of 22-year-old man with nontraumatic intracystic hemorrhage into a middle cranial fossa arachnoid cyst associated with a contiguous subacute subdural hematoma. Arachnoid cysts are benign intra-arachnoidal fluid collections frequently detected incidentally during neuroimaging. Rare complications of arachnoid cysts such as intracystic hemorrhage or subdural hematomas and subdural hygromas typically occur after head trauma. Our review of the literature identified fewer than 30 cases of arachnoid cysts with complicating intracystic hemorrhage and ipsilateral subdural hematomas.

Keywords: CT, computed tomography; MRI, magnetic resonance imaging.

Figure 1

22-year-old man with complicated arachnoid cyst. A, Initial non-contrast axial head CT at the level of the atria of the lateral ventricles. There is a left sided subdural hematoma (yellow arrow) that is of the same attenuation as the adjacent brain parenchyma. Both mass effect and midline shift are demonstrated. B, Inferiorly, a hemorrhagic, round, extra-axial mass (green arrow) is seen in the anterior aspect of the left middle cranial fossa on non-contrast axial head CT. C, CT bone window image at the same level as Fig. 1A demonstrates scalloping of the inner table of the calvarium (green arrow).

Figure 2

22-year-old man with complicated arachnoid cyst. A, Axial T2-weighted MR image. The lesion is transected in the middle by the arachnoid membrane (blue arrow). Both segments (green and yellow arrows) demonstrate signal that is isointense to the adjacent brain parenchyma. B, Axial T1-weighted MR imaging better demonstrates the lesion’s complex nature. The lesion represents an arachnoid cyst (green arrow) which shows evidence of hemorrhage as demonstrated by the presence of T1 shortening. The surrounding subdural hematoma (yellow arrow) shows well demarcated prominent T1 shortening indicative of hemorrhage. C, Contrast enhanced axial T1-weighted MR imaging shows enhancement of the dural membrane but does not show enhancement within the arachnoid cyst (green arrow). The arachnoid membrane (blue arrow) separates hemorrhage in the subdural compartment (yellow arrow) from hemorrhage inside the arachnoid cyst (green arrow). D, Coronal contrast enhanced T1-weighted MR imaging shows the arachnoid cyst (green arrow), arachnoid membrane (blue arrow), and subdural hematoma (yellow arrows).

Figure 3

22-year-old man with complicated arachnoid cyst. Intraoperative visualization of the subarachnoid space, arachnoid membrane, and sylvian fissure after evacuation of the subdural hematoma.

Figure 4

22-year-old man with complicated arachnoid cyst. Postoperative non-contrast axial head CT. The hypoattenuation in the anterior aspect of the left middle cranial fossa represents the fenestrated arachnoid cyst (green arrow). Air within the cyst reflects communication between the structure and the drained subdural hematoma.