Restricted diffusion in a thrombosed anterior cerebral artery aneurysm mimicking a dermoid cyst

Ring enhanced aneurysm due to vasa vasorum of aneurysm wall mimicking a metastatic brain tumor

Background

A spherical intracranial mass can be occasionally misdiagnosed due to the lack of typical radiographic features. Completely thrombosed intracranial aneurysms (CTIA) are uncommon, but a possible differential diagnosis must be considered to guarantee the best surgical approach for these lesions.

Case Description

Here, we report an extremely rare case of a right frontal mass mimicking a brain tumor, in which the surgery unveiled a CTIA of the right middle cerebral artery (MCA). A 56-year-old woman presented with right hemiparesis and mild headache. Magnetic resonance imaging (MRI) revealed a right frontal mass with peripheral edema. The lesion enhanced on initial and follow-up MRI of the brain. Subsequent vascular studies and metastatic workup were negative. A temporal craniotomy with neuronavigation (Brain Lab AG, Germany) was performed and an intraoperative diagnosis of a thrombosed aneurysm along the branch of the MCA was established. The aneurysm was successfully trapped and resected. The patient did not exhibit any postoperative neurological deficits.

Conclusion

This is the rare report of a ring enhanced completely thrombosed aneurysm due to vasa vasorum which is misdiagnosed as metastatic brain tumor. In case of an intracranial ring enhanced mass with signs of intralesional hemorrhage and peripheral edema, CTIA should be considered as a possible differential diagnosis.

Distal middle cerebral artery dissection with concurrent completely thrombosed aneurysm manifesting as cerebral ischemia. A case report and review of the literature

We report the case of a 70-year-old woman who presented with an acute ischemic stroke involving the left frontal operculum secondary to an M2 dissection and a concomitant completely thrombosed aneurysm of the left distal middle cerebral artery. Initial imaging work-up was inconclusive due to the lack of typical radiographic features and only repeated imaging studies pointed towards the presence of an arterial dissection combined with a completely thrombosed aneurysm. The aneurysm was partially clipped and wrapped with excellent clinical result at 1-year follow-up. The clinical, imaging and therapeutic challenges of this rare entity are discussed.

Completely Thrombosed Distal Middle Cerebral Artery Aneurysm Mimicking a Cavernous Angioma: Case Report and Review of the Literature

BACKGROUND

Distal middle cerebral artery (MCA) aneurysms originate from branches of MCA distal to its main bifurcation or the peripheral branches. Distal MCA aneurysms are uncommon compared with saccular aneurysms, which develop along the proximal trunks of MCA. However, thrombotic aneurysms, characterized by organized intraluminal thrombus and solid mass, are frequently in the large and giant size range, whereas complete thrombosis of non-giant MCA aneurysms is very rare.

CASE PRESENTATION

We present the clinical case of a 53 years-old woman with a completely thrombosed medium distal MCA aneurysm mimicking a cavernous angioma. She came to our emergency department after the onset of tinnitus and persistent headache. Magnetic resonance imaging performed subsequently showed a nodular mass surrounded by edema located in the temporal lobe with a homogeneous peripheral contrast enhancement. Furthermore, angiography showed regular flow in the MCA and confirmed the diagnosis of cavernous angioma. The patient underwent surgery, and the lesion was found to be a thrombosed aneurysm originating from the distal temporal branch of the left MCA (M2 segment).

CONCLUSIONS

To our knowledge, this is the first report of a thrombosed distal medium MCA aneurysm that mimicked a cavernous angioma. The completely thrombosed aneurysm can be confused with intracranial lesions or cavernous malformations, which can have similar radiographic features without angiographic anomalies, so it is mandatory to consider the possibility of a thrombosed aneurysm for a correct differential diagnosis.

Discrepancy between Angiography and Operative Findings of Small Side Wall Aneurysms in Atherosclerotic Parent Arteries

Preoperative evaluation of precise aneurysmal geometry is important for the treatment of intracranial aneurysms. We present two cases of unclippable side wall aneurysms due to their extremely low dome height, which appeared as saccular in the preoperative image because of a comparatively narrow atherosclerotic parent arterial lumen. In both cases, a calcified vessel wall was noted preoperatively. Lack of a definitive neck and abrupt discrepancy between the fragile aneurysmal wall and the atherosclerotic parent arterial wall was confirmed intraoperatively in both cases. This study describes an illustrative mechanism for the finding with emphasis on the importance of its preoperative diagnosis. Intracranial atherosclerosis associated with small side walled aneurysms may lead to overestimation of aneurysm height on preoperative imaging of the intravascular compartment.

Thrombosed large middle cerebral artery aneurysm mimicking an intra-axial brain tumor: case report and review of literature

This case report presents a fully thrombosed large aneurysm of middle cerebral artery mimicking an intra-axial brain tumor in a 54-year-old male patient. A small mass like lesion was found incidentally in right frontal area. Brain magnetic resonance image showed dark signal intensity on T2-weighted images and peripheral high signal intensity on T1-weighted images with peripheral rim enhancement. We considered intra-axial tumors such as glioma or metastatic tumor as a differential diagnosis. The lesion was approached transcortically, and intraoperatively, the lesion was found to be a large thrombosed aneurysm originating from the lateral lenticulostriate artery of right middle cerebral artery. One vascular clip was applied at the parent artery, and the thrombosed aneurysm was totally removed. There have been many reports of other intracranial lesions wrongly diagnosed as intracranial neoplasms. And thrombosed aneurysms mimicking intracranial neoplasm have been reported in 4 cases previously. According to those case reports, there were no efficient imaging tools to differentiate between these thrombosed aneurysms and intracranial neoplasms. We reviewed those reports and considered about the efficient method to diagnosed accurately before surgery. To sum up, when a patient presents with an intracranial lesion lying on the course of major or distal cerebral arteries, the surgeon should have thrombosed aneurysm in mind as one of the differential diagnosis and be prepared when surgically treating such lesions.