giant serpentine aneurysm was described in 1977 by segel and mclaurin14 ) as a subcategory of giant aneurysms , distinct from the saccular variety .
patients with a large or giant aneurysm of the internal carotid artery ( ica ) located in the paraclinoid area often present with cranial nerve symptoms .
cavernous ica aneurysms can have a mass effect on the oculomotor , trochlear , or abducens nerve , resulting in internal or external ophthalmoplegia .
it is most likely associated with carotid ophthalmic or hypophyseal aneurysms , but rarely occurs with a cavernous ica aneurysm .
we report a patient with a serpentine cavernous ica aneurysm who presented with visual symptoms that progressively improved after endovascular coil trapping .
a 44-year - old woman presented with decreased right visual acuity of 1-month duration . two weeks previously , she had complained of dry eye and was diagnosed with optic neuritis at a private clinic .
the examination showed a decrease in her right visual acuity to 0.04 compared to 1.0 on the left side .
the right visual field showed a 3/4 defect involving all but the right lateral upper quadrant . on magnetic resonance imaging ( mri ) of the brain , a large aneurysm , 19  12 mm in size , well marginated , and oval - shaped , with a heterogeneous signal void was seen in the right parasellar region , probably in the cavernous sinus ( fig .
computed tomography angiography ( cta ) showed fusiform dilatation of the right cavernous ica , suggestive of a fusiform aneurysm with an approximate size of 30  20 mm ( fig .
fundus photography showed right optic nerve atrophy with a pale neural rim on the right optic disc ( fig .
the findings on transfemoral catheter angiography ( tfca ) were similar to those obtained with mri and cta .
4a ) , followed by observation of the collateral flow during temporary occlusion of the parent artery . after 20 min , the collateral flow was deemed tolerable .
the patient was then evaluated by single - photon emission computed tomography ( spect ) . because the results showed well - maintained vascular reserve ( fig .
4b ) , we chose to perform coil embolization of the large serpentine aneurysm with occlusion of the parent artery ( fig .
postoperatively , the patient had no obvious neurological deficits . a second round of mri and spect 24 h after the embolization showed no abnormalities .
nine months after coil embolization , the patient 's visual field and visual acuity had improved considerably ( table 1 , fig .
radiologically these aneurysms may be serpentine , whereas macroscopically they may be referred to as large fusiform aneurysms , and pathologically as dissecting , atherosclerotic , or dysplastic .
this confusion about the exact nature of the aneurysm can be resolved by considering the natural history , clinical presentation , and treatment rationale .
patients with dissecting intracranial aneurysms typically present with subarachnoid hemorrhage and have a high incidence of early rebleeding.12 ) however , patients with large fusiform lesions present with a progressive mass effect and are at less risk of suffering hemorrhage.1)16 ) the imaging features of large serpentine aneurysms are also characteristic.1)11 ) computed tomography shows an extra - axial mass originating from the artery with intramural thrombosis .
magnetic resonance imaging shows a heterogeneous oval mass , indicative of thrombi of different ages , and a " flow - void " lesion with an enhanced rim .
there are several reports of surgical ( hunterian ) ligation , trapping , resection , and thrombectomy with and without vascular bypass.2)4)8)14)16 ) surgical removal alone is a direct , attractive treatment .
several therapeutic options have been reported.1)3)9)13)14 ) however , the perioperative morbidity and mortality are 30 - 35% .
one reason is the difficulty preserving the surrounding vessels during surgical dissection and excluding the aneurysm from the normal cerebral vasculature .
in addition , the functionally distal areas of the brain are supplied by the channel within the serpentine aneurysm .
therefore , the goal of surgical treatment is the elimination of the blood flow to the aneurysm and maintenance of the blood flow to the distal cerebral territory .
first , the surgical dissection to expose the aneurysm may require aggressive retraction , resulting in brain injury .
second , adjacent important neurovascular structures can be compressed by the aneurysm and may adhere tightly to its surface .
third , the neck of a serpentine aneurysm can be difficult to identify in the surgical field .
some large serpentine aneurysms have been managed successfully using endovascular procedures intended to induce thrombosis and shrinkage of the mass.1 ) this is an indirect treatment strategy compared with surgical removal , but it has several advantages .
an endovascular treatment does not require extensive retraction that can cause injury of the normal cerebral tissue due to microsurgical dissection .
furthermore , an endovascular treatment can be used to obtain clear angiographic images to visualize the serpentine vascular channels on the aneurysm surface .
clinical improvement following endovascular occlusion of an aneurysm causing a mass effect has been reported in > 75% of cases.5)6)7)10)11 ) a dramatic decrease in aneurysm size is a common finding on mri after successful endovascular occlusion.15)17 ) one report suggested that occlusion of the parent artery is more effective at decreasing the volume and relieving the mass effect than is endosaccular occlusion,17 ) which may result in the accumulation of embolic material in the aneurysm , thereby limiting shrinkage of the aneurysm .
nevertheless , endosaccular obliteration has been effective in reducing the mass effect.10 ) it has the advantage of preserving the normal brain and vascular structures .
, we did not clearly differentiate whether the pathogenesis of the visual disturbance involved embolism from the aneurysm itself or pulsatile compression by the aneurysm sac .
however , our patient with a serpentine aneurysm presenting as a visual disturbance was treated by endovascular trapping .
this was a better therapeutic choice than proximal occlusion because trapping can block both anterograde and retrograde flow , potentially reducing intra - aneurysmal pressure and promoting thrombogenesis .
careful studies were performed before trapping , using cross - compression and balloon occlusion to evaluate the cerebral hemodynamics .
however , in patients with poor collateral flow , extracranial - intracranial bypass surgery should be considered .
nonetheless , even in those cases , endovascular trapping is a useful option , particularly when performed in combination with bypass surgery .
we described the case of a patient with a large serpentine aneurysm who presented with visual disturbances .
this patient was treated successfully with coil embolization after careful studies of the intracranial hemodynamics .
 this report describes a case of a serpentine fusiform aneurysm of the internal carotid artery in a patient who presented with visual disturbances . 
 the serpentine aneurysm was treated successfully by coil trapping and occlusion of the parent artery , accompanied by balloon dilation . 
 nine months post - operatively , the patient 's visual acuity had improved considerably . 
INTRODUCTION
CASE REPORT
DISCUSSION
CONCLUSION