Spontaneous Acute Subdural Hematoma Associated with Arachnoid Cyst and Intra-cystic Hemorrhage

Abstract

Arachnoid cysts (ACs) are congenital, extra-axial lesions containing fluid similar to the composition of cerebrospinal fluid. Usually found incidentally, these lesions are observed with serial imaging to document their growth patterns and stability, and are then followed conservatively until clinical symptoms develop. Surgical options for symptomatic arachnoid cysts include cyst aspiration, cyst evacuation with fenestration into the subarachnoid space, and shunt procedures including cysto-peritoneal and cysto-ventricular shunts. Intra-cystic hemorrhage and subdural hematoma are rare and more emergent sequelae of ACs that may require an emergent craniotomy. This case report further documents a rare cause of spontaneous subdural hematoma, as well as serves as a pivot point for further discussion into whether continued neuroimaging surveillance in patients with ACs would prove to be beneficial.

Keywords: arachnoid cyst; intra-cystic hemorrhage; spontaneous subdural hematoma.

Figure 1. Magnetic resonance imaging of the brain without contrast

MRI obtained two years prior to admission. A: Coronal T1-weighted image demonstrating a left frontal hypointense extra-axial lesion. B: Coronal T2-weighted image demonstrating a left frontal hyperintense extra-axial lesion. Both images are suggestive of an arachnoid cyst. MRI: Magnetic resonance imaging

Figure 2. Admission computed tomography of the head

A: Coronal view bone window sequence demonstrating scalloping of the calvarium (arrow) in the region of the known left frontal arachnoid cyst. B: Coronal view demonstrating an isodense left frontal extra-axial fluid collection {arrow) with mass effect upon the left cerebral hemisphere with resultant left-to-right midline shift. C: Axial view demonstrating a loculated hyperdense (up-arrow) and isodense extra-axial fluid collection in the region of prior AC, suspicious for intra-cystic hemorrhage (down-arrow) and subdural hematoma.

Figure 3. Postoperative noncontrast head computed tomography

Axial view demonstrating the evacuation of a subdural hematoma and an arachnoid cyst with intra-cystic hemorrhage. A subdural drain (arrow) was placed intraoperatively to drain the residual subdural hematoma.

Figure 4. Noncontrast head computed tomography two months after craniotomy

A: Coronal view demonstrating resolution of subdural hematoma as well as no residual arachnoid cyst (arrow). B: Axial head computed tomography demonstrating resolution of left cerebral convexity subdural hematoma (arrow).