A Case of Cryptogenic Recurrent Cerebral Fusiform Aneurysms involving the Distal Anterior Circulation Arthur K Omuro, DO Department of Neurology, Desert Regional Medical Center, Palm Springs, California Case Report On outpatient follow up visit at the interventional clinic, the patient revealed that she had undergone intravascular stenting of an interval new right pericallosal artery fusiform aneurysm at a different facility approximately 9 months after her initial presentation. About 20 months after her initial presentation and 11 months after the stent placement, the patient was taken for a repeat diagnostic cerebral angiogram for further evaluation: Discussion Background Fusiform aneurysms are non-saccular dilatations involving the entire circumference of the arterial wall caused by traumatic dissections, infections, atherosclerotic disease, and collagen vascular disorders. One of the defining features includes the communication between the true lumen and false lumen through a defect of the internal elastic lamina1. This is thought to lead to a formation of an intramural hematoma, which may progress to disrupt the adventitia to result in subarachnoid hemorrhage. Conversely, hematoma expansion between the internal elastic lamina and the tunica media may lead to vascular stenosis/occlusion to cause ischemic stroke2. Amongst the other etiologies with saccular aneurysms being the most common type, fusiform aneurysms represent only a small proportion of intracranial aneurysms. Furthermore, when present, these aneurysms more commonly involve the vertebrobasilar system. However, there have been case reports of patients with distal anterior cerebral aneurysms in the setting of an azygous ACA3. Interestingly, patient’s with distal ACA territory lesions were found to have better outcomes following intervention compared to other location4. The following case is a discussion of a 22-year-old female who presented with a subarachnoid hemorrhage due to a ruptured distal anterior cerebral fusiform aneurysm found to have recurrence on follow up. A 22-year-old Vietnamese female with no significant past medical history presented to the emergency department with new onset seizure. Upon arrival, the patient was witnessed to have recurrent convulsions without return to baseline so she was intubated and sedated. Initial noncontrast CT head demonstrated diffuse subarachnoid hemorrhage (modified Fisher 3, Hunt & Hess 5), with an anterior interhemispheric intracerebral hemorrhage. The patient was taken for diagnostic cerebral angiogram shown below: This case discusses a rare type of intracranial aneurysm in the form of a fusiform aneurysm in a less commonly reported location of the callosomarginal branch of the ACA, further distinguished by the recurrence of a fusiform aneurysm in the pericallosal branch of the ACA. In this otherwise healthy 22-year-old female, a reasonable etiology for fusiform aneurysms could not be established despite her prolonged hospital course and continued outpatient follow up. Pertinent negatives included systemic/CNS infections, malignancies, and phenotypical manifestations of common collagen disorders. An argument could be made that the new pericallosal fusiform aneurysm may have been the result of surgical trauma from manipulation/clipping of the nearby vessels; however, the explanation for her presenting lesion still remains unknown and though a rare cause, genetic testing for collagen vascular disorders may be warranted in such patients5. a b a b Figure 2: (a) Lateral projection of right internal carotid injection (b) AP projection The repeat study demonstrated complete obliteration of the previously seen right callosomarginal fusiform aneurysm; however, an interval new stented right pericallosal artery with fusiform dilatation measuring 2.5 x 2.5 x 9.5 mm was also seen. Of note, the patient’s family history was negative for ischemic strokes, intracranial hemorrhages, or aneurysms. In addition, social history was largely negative with the exception of occasional marijuana; she otherwise denied any current or previous history of illicit drug abuse. References Figure 1: (a) Lateral projection of right internal carotid injection (b) AP projection Diagnostic cerebral angiogram demonstrated a 10.2 x 6.1 x 9.5 mm right callosomarginal branch aneurysm/pseudoaneurysm. Given the distal location of the vascular lesion, the patient went for emergent surgical clipping to secure the aneurysm. Pathology report of the surgically resected lesion reported evidence of a fusiform aneurysm with both acute and chronic inflammation suggestive of an mycotic/septic etiology, despite the lack of systemic infection during the course of the patient’s admission. After an extended and complex hospital course, the patient was transferred to acute rehab for further recovery. 1. Nakatomi H, Segawa H, et al. Clinicopathological Study of Intracranial Fusiform and Dolichoectatic Aneurysms: Insight on the Mechanism of Growth. Stroke 2000; 31:896-900. 2. Park SH, Yim MG, et al. Intracranial Fusiform Aneurysms: It’s Pathogenesis, Clinical Characteristics and Managements. J Korean Neurosurg Soc 2008; 44:116-123. 3. Saponiero R, Toriello A, et al. Distal Anterior Cerebral Artery Aneurysms: Endovascular or Surgical Treatment? Neuroradiology Journal 2008; 21:251-254. 4. Aguiar PHP, Estevao IA, et al. Distal Anterior Cerebral Artery (Pericallosal Artery) Aneurysms: Report of 19 Cases and Literature review. Turk Neurosurg 2017; 27(5):725-731. 5. Barletta EA, Ricci RL, et al. Fusiform aneurysms: A review from its pathogenesis to treatment options. Surgical Neurology International 2018; 9:189. Objective To discuss a unique case of recurrent fusiform aneurysms involving the distal anterior cerebral circulation.