An Unusual Case of Two Large Aneurysms Arising from Opposite Walls of Right Internal Carotid Artery Cavernous Segment and its Management

Sir, Intracranial aneurysms are found in 2%–5% of the population in the fifth and sixth decades of life. Aneurysms of the cavernous internal carotid artery represent less than 1% of intracranial aneurysms. These aneurysms can be idiopathic or result from trauma and infections.[1] They are often asymptomatic and are considered benign. Asymptomatic cavernous internal carotid aneurysms can be dangerous and may require aggressive treatment. They can present with either a carotico-cavernous fistula when it is ruptured in the cavernous sinus or subarachnoid hemorrhage when ruptured in the subarachnoid space. Other presentation includes cranial nerve palsy due to compression of the cavernous sinus.[2] Aneurysms arising from the opposite wall of the cavernous segment of the internal carotid artery are unusual. There are some cases in the literature of large bilateral aneurysms of the cavernous segment of the internal carotid artery; however, to date, no case has been reported of a dual large opposite walled aneurysm.[3] These unusual aneurysms can result from connective-tissue disorder, affecting the collagen and proteoglycans that construct the extracellular matrix, which causes the weakening of the vessel wall.[4] We report a unique case of two large aneurysms arising from the opposite wall of the cavernous segment of the right internal carotid artery and its management. A 40-year-male patient presented to the outpatient department with complaints of intermittent headaches for 6 months. The severity of the headache was mild to moderate and continuous, not subsiding with medications. The patient also complained about diplopia for the past 2 months. On examination, he was conscious and oriented to time, place, and person. His neurological examination revealed no abnormality except right sixth nerve palsy. There was no evidence to suggest the presence of other comorbidities. The presence of connective tissue disorders such as Ehlers–Danlos syndrome (EDS), Neurofibromatosis type-1 (NF1), and Marfan’s syndrome was also ruled out. CT scan was suggestive of mass lesion in the right cavernous sinus region [Figure 1a]. Magnetic resonance imaging (MRI) of the brain revealed a heterogeneously enhancing mass lesion measuring approximately 22 mm × 20 mm × 18 mm in the right cavernous sinus which was iso to hypointense on T2 weighted images. In addition, flow voids were noticed on T2-weighted images [Figure 1b-d]. Digital subtraction angiography (DSA) of the brain revealed two large aneurysms arising from the right petrous cavernous junction of the internal carotid artery. One of the aneurysms was 7.4 mm × 6.7 mm in size originating from the dorsal wall of the ICA and projecting posterosuperior direction. The other was approximately 17.31 mm × 9.7 mm in size arising from the ventral wall and projecting anterolateral direction [Figure 2a-c]. Three-dimensional rotational angiography revealed a better understanding of aneurysmal morphology [Figure 3a and b].Figure 1: CT scan brain plain study showing right cavernous sinus soft tissue mass lesion with calcified specks (a). Magnetic resonance imaging (MRI) of the brain showing a heterogeneously enhancing mass lesion measuring approximately 22 mm × 20 mm × 18 mm in the right cavernous sinus axial view (b) and coronal view (c) which was iso to hypointense on T2-weighted images (d). Flow voids noticed on T2-weighted imagesFigure 2: Digital subtraction angiography (DSA) of the brain showing two large size aneurysms arising from the petrous cavernous junction of the right internal carotid artery. One of the aneurysms was 7.4 mm × 6.7 mm in size originating from the dorsal wall of the ICA and projecting posterosuperior direction. The other was approximately 17.3 mm × 9.7 mm in size arising from the ventral wall and projecting anterolateral direction; lateral view (a), anteroposterior view (b), and magnified oblique view (c)Figure 3: Three-dimensional rotational angiography revealed a better understanding of the aneurysmal morphology (a and b). A pipeline shield (size: 4 mm × 25 mm) flow diverter (FD) with a microcatheter positioned across the neck of the aneurysms (c). Complete opening and wall opposition of FD (d)Given the symptomatic nature of the aneurysms, the decision was taken regarding intervention. The patient underwent flow diverter treatment for the right cavernous carotid aneurysms. He received antiplatelet medication (aspirin 150 mg and clopidogrel 75 mg) for 5 days before the procedure. The procedure was performed under general anesthesia. The right femoral artery was punctured, and an 8F arterial short sheath was inserted. Approximately 5000 units of heparin were given intraarterial at the start of the procedure, and 1000 units were repeated hourly intravenous. Under road map guidance, a 7F Neuronmax guiding catheter was placed in the proximal right internal carotid artery and through which a 6F Navion catheter was placed in the distal internal carotid artery. A phenom microcatheter was advanced over 0.014 Chikai microguide wire, and the lesion was crossed. A microwire was removed, and a pipeline shield (size: 4 mm × 25 mm) flow diverter (FD) was passed through the microcatheter and positioned across the neck of the aneurysms [Figure 3c]. FD was deployed to cover the neck of the aneurysms. The post-deployment run showed stagnation of the contrast material in the aneurysms with a good distal flow. Complete wall opposition of FD was confirmed [Figure 3d]. The procedure was uneventful, and the total procedure time was around 100 min. The patient recovered well from anesthesia without any new neurological deficit. Oral antiplatelet medication (tab aspirin 150 mg and clopidogrel 75 mg daily) was started the next day, and the patient was discharged on the 4th postoperative day. His headache was reduced at the time of discharge, but his diplopia was persistent. At the 6-month follow-up, MRI brain post-contrast images showed near-complete resolution of right cavernous aneurysms [Figure 4a]. Follow-up DSA revealed almost near-complete obliteration of both the aneurysms [Figure 4b and c]. In addition, the right lateral rectus palsy completely improved [Figure 4d].Figure 4: At the 6-month follow-up, MRI brain post contrast images showing near-complete resolution of right cavernous aneurysms (a). Follow-up DSA showing almost near complete obliteration of both the aneurysms (b,c). Clinical photograph showing right lateral rectus palsy completely improved (d)Cavernous internal carotid artery aneurysms constitute 1% of all intracranial aneurysms. They form mostly due to type I collagen and fibronectin loss in the adventitia and muscularis mucosa, respectively. Due to continuous, pulsatile blood flow, the vessel wall gets weakened and causes stretching of the aneurysm dome.[5] These aneurysms are less likely to rupture due to their close location to the anterior clinoid process and the dura of the cavernous sinus. These structures partially shield the aneurysm dome and buttress it against hemodynamic forces.[6] The cavernous internal carotid artery aneurysms are usually asymptomatic. Symptomatic patients present with diplopia, decreased vision, facial pain, or numbness due to the compression of cranial nerves.[7] Our patient had right-sided lateral rectus palsy due to compression of the 6th nerve by the aneurysms and headache. Though the natural history of cavernous carotid aneurysms and their bilateral occurrence are very well documented in the literature,[8,9] we have not found any case of two aneurysms arising from the opposite wall of the same artery. These types of aneurysms can be associated with connective tissue disorders such as Marfan syndrome, NF1, and EDS. Marfan syndrome is caused by a defect in fibrillin, a glycoprotein that is a structural component of microfibrils found in many tissues. There is an association between fibrillin defects in the pathogenesis of intracranial aneurysms.[10] EDS is also a common connective tissue disorder associated with aneurysms, commonly EDS Type 4. The extreme fragility of arteries is related to multiple aneurysm formation, spontaneous rupture, and dissection.[11] Neurofibromatosis type 1 presents with mesodermal dysplasia, affecting arteries and resulting in stenosis or aneurysmal degeneration.[12] We evaluated our patient for connective tissue diseases, but none of these disorders were detected. This suggests that there may be some other mechanism responsible for such an occurrence. Management of cavernous carotid aneurysms is a topic of interest. Usually, asymptomatic patients do not require treatment. However, when the aneurysm arises from the genu of the cavernous segment of the internal carotid artery, the aneurysm extends into the subarachnoid space or the sphenoid sinus, and in the case of the radiological evidence of a progressive increase in the size of the aneurysm, one should consider the treatment in even asymptomatic patients. Symptomatic patients always require treatment; symptoms include subarachnoid hemorrhage, epistaxis, unbearable ipsilateral facial or retro-orbital pain, diplopia, and progressive visual loss.[13] The treatment options include micro neurosurgery in the form of bypass and endovascular procedures. Mortality rates in microsurgery such as a superficial temporal artery–middle cerebral artery bypass are reported to be 6%–22%.[14] Endovascular approaches include parent artery occlusion, stent-coil embolization, balloon-assisted coiling, and flow diverters. Since their introduction, flow diverters have become the modality of choice for endovascular management of these aneurysms. Flow diverters have provided a promising alternative for repairing multiple aneurysms in a single artery.[15] In our case, we had thought about both flow diverter and stent graft as options, but there was concern about the trackability of the stent graft as there were two significant bands and tortuosity in the proximal cervical internal carotid artery. Thus, a flow diverter treatment was chosen to manage such kinds of dual aneurysms. Our case highlights two opposite-wall aneurysms arising from the cavernous internal carotid artery. Multiple aneurysms in the same artery or arterial segment can be due to connective tissue disorders. The use of flow diverters for such aneurysms can be an ideal technique for the complete exclusion of aneurysms from circulation with good clinical outcomes. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.