Association Between an Arachnoid Cyst and Intracranial Aneurysms
Association Between an Arachnoid Cyst and Intracranial Aneurysms
The authors report on a 63-year-old man initially admitted to an outside hospital for altered mental status and respiratory distress. A head computed tomography scan disclosed a right frontal cystic mass, suspected to be a neoplasm. An open biopsy was performed at an outside institution, and on visualization of the cyst, an aneurysm was found incidentally. Postoperatively, an angiogram and magnetic resonance image confirmed the presence of a distal right M1 segment aneurysm. The patient was transferred to our institution where, in addition to the middle cerebral artery lesion, a right anterior choroidal artery aneurysm was found intraoperatively; the necks of both aneurysms were clipped successfully. A review of the literature revealed 14 additional cases of intracranial aneurysms associated with arachnoid cysts. Data in the present report highlight the importance of considering an intracystic aneurysm in the differential diagnosis when reviewing cases that involve a cystic mass with a mural nodule. The authors provide a comprehensive summary of documented cases of aneurysms associated with arachnoid cysts. In addition, they include a discussion of prevailing thoughts on the origin and evolution of arachnoid cysts.
In General, when CT scans reveal a cystic mass with a mural nodule, a malignant glioma or other tumor is highly suspected. There have been sporadic reports of arachnoid cysts associated with aneurysms resembling a cystic mass with a mural nodule, but no review in which these findings are summarized. Arachnoid cysts have been previously associated with chronic subdural hematomas and less frequently with aneurysms. More arachnoid cysts are being diagnosed given the in creased frequency of neuroimaging procedures. On neuroimages, these lesions appear as smooth-bordered, noncalcified, extraparenchymal cystic masses with a density similar to CSF and no enhancement with the intravenous administration of contrast material. They can cause expansion and remodeling of nearby bone, which typically depicts its chronic nature. Most occur in the anterior half of the middle cranial fossa.
An arachnoid cyst is a leptomeningeal cyst, perhaps congenital, forming from the splitting of arachnoid membranes. It can be categorized as primary or secondary. Pri mary arachnoid cysts are developmental abnormalities, whereas secondary arachnoid cysts can result from trauma, infection, surgery, or previous hemorrhage. A num ber of hypotheses have evolved regarding the origins of arachnoid cysts and their potential relationship to in tracranial aneurysms. Here, we describe a case encountered at our institution and review the literature documenting additional institutional experiences with arach noid cysts associated with aneurysms.
Abstract and Introduction
Abstract
The authors report on a 63-year-old man initially admitted to an outside hospital for altered mental status and respiratory distress. A head computed tomography scan disclosed a right frontal cystic mass, suspected to be a neoplasm. An open biopsy was performed at an outside institution, and on visualization of the cyst, an aneurysm was found incidentally. Postoperatively, an angiogram and magnetic resonance image confirmed the presence of a distal right M1 segment aneurysm. The patient was transferred to our institution where, in addition to the middle cerebral artery lesion, a right anterior choroidal artery aneurysm was found intraoperatively; the necks of both aneurysms were clipped successfully. A review of the literature revealed 14 additional cases of intracranial aneurysms associated with arachnoid cysts. Data in the present report highlight the importance of considering an intracystic aneurysm in the differential diagnosis when reviewing cases that involve a cystic mass with a mural nodule. The authors provide a comprehensive summary of documented cases of aneurysms associated with arachnoid cysts. In addition, they include a discussion of prevailing thoughts on the origin and evolution of arachnoid cysts.
Introduction
In General, when CT scans reveal a cystic mass with a mural nodule, a malignant glioma or other tumor is highly suspected. There have been sporadic reports of arachnoid cysts associated with aneurysms resembling a cystic mass with a mural nodule, but no review in which these findings are summarized. Arachnoid cysts have been previously associated with chronic subdural hematomas and less frequently with aneurysms. More arachnoid cysts are being diagnosed given the in creased frequency of neuroimaging procedures. On neuroimages, these lesions appear as smooth-bordered, noncalcified, extraparenchymal cystic masses with a density similar to CSF and no enhancement with the intravenous administration of contrast material. They can cause expansion and remodeling of nearby bone, which typically depicts its chronic nature. Most occur in the anterior half of the middle cranial fossa.
An arachnoid cyst is a leptomeningeal cyst, perhaps congenital, forming from the splitting of arachnoid membranes. It can be categorized as primary or secondary. Pri mary arachnoid cysts are developmental abnormalities, whereas secondary arachnoid cysts can result from trauma, infection, surgery, or previous hemorrhage. A num ber of hypotheses have evolved regarding the origins of arachnoid cysts and their potential relationship to in tracranial aneurysms. Here, we describe a case encountered at our institution and review the literature documenting additional institutional experiences with arach noid cysts associated with aneurysms.
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