Giant aneurysm associated with a large cyst

Abstract

ness in his upper and lower extremities and difficulty with speech and writing. He reported a history of subarachnoid hemorrhage that had occurred 30 years earlier, but could not provide detailed information. Contrast-enhanced computerized tomography scanning revealed a large cyst in the left temporal lobe with a heterogeneous roundish nodule in the lesion (Fig. 1). On magnetic resonance imaging, the cyst was isointense and the roundish nodule appeared to be a heterogeneous high-intensity lesion that was slightly enhanced on the T1-weighted image after addition of gadolinium–diethylenetriamine pentaacetic acid (Fig. 2). Digital subtraction angiography revealed an aneurysm arising from the horizontal portion of the left middle cerebral artery (Fig. 3). During the operation, the cyst, which contained serous xanthochromic fluid, was observed to occupy the space between the frontal lobe, the temporal lobe, and the wall of the aneurysm. No communication between the subarachnoid space and the cyst was found. Partial removal of the cyst was performed so that the fluid could continuously drain into the subarachnoid space. Postoperatively, the cyst remained collapsed. To our knowledge, there is no reported case of a giant aneurysm accompanying a cyst, although an arteriovenous malformation has been observed to coexist with a cyst.1,5 There are three possible causes of the cyst formation: 1) direct exudate from the aneurysm;2,3 2) hematoma formed by the initial subarachnoid hemorrhage, which expanded and resulted in a large cyst;4 and 3) infarction in this area, which enlarged gradually, perhaps due to the pulsation of the aneurysm, and resulted in the cyst.