2025 Volume 19 Issue 1 Article ID: cr.2025-0023
Objective: We report a case of subarachnoid hemorrhage (SAH) due to the ruptured dissection aneurysm of the frontopolar artery (FPA), which was successfully treated with parent artery occlusion (PAO).
Case Presentation: A 42-year-old woman was brought to our hospital suffering from sudden severe headache and vomiting. Four days prior to admission, she experienced a mild frontal headache. Head computed tomography (CT) revealed SAH with a right medial frontal lobe hematoma. On the day of admission, we performed cerebral angiography, and a fusiform aneurysm was found in the FPA branching from the proximal right anterior cerebral artery (A1), which was suspected to be the dissection. We performed PAO for the right FPA. The patient was discharged with mRS:0 on the 27th day of admission. Several reports describe that the FPA usually bifurcate from the A2 segment, and it is rarely dissected. However, in our case, the FPA originated from the distal part of the A1 segment, and the dissection aneurysm of FPA ruptured.
Conclusion: To the best of our knowledge, this is the first reported case of SAH due to a ruptured dissection aneurysm of FPA treated by PAO.
Subarachnoid hemorrhage (SAH) is commonly caused by ruptured aneurysms, but it is also known to be caused by the dissection of cerebral arteries.1) In Japan, the vertebral artery (VA) and anterior cerebral artery (ACA) are known to be the most common sites of cerebral artery dissection.2) Several cases of SAH due to ruptured aneurysms of frontopolar artery (FPA) treated surgically and endovascularly were found,3–6) but we did not find reports of FPA dissection and parent artery occlusion (PAO) for FPA. Here, for the first time, we describe a case of SAH due to FPA dissection that was treated with PAO.
A 42-year-old woman was brought to our hospital for sudden severe headache and vomiting. She had a history of hypertension, but had not suffered any head injury. Four days prior to admission, she experienced a mild frontal headache. Head computed tomography (CT) on the day of admission showed SAH with a right medial frontal lobe hematoma (Fig. 1A). Her level of consciousness at the time of transport was E3V4M6 on the Glasgow coma scale, and motor paralysis equivalent to MMT4 was observed in the left lower limb, which was determined to be World Federation of Neurosurgical Societies (WFNS) Grade Ⅲ. Head CT angiography did not show an obvious source of the hemorrhage (Fig. 1B). Subsequently, we performed cerebral angiography, and a fusiform aneurysm was found in the branching artery of the proximal right ACA (A1) (Fig. 1C). We determined that the same site was the source of SAH, combined with the distribution of the hematoma. Since the patient was right-handed and already had the right medial frontal lobe hematoma, we determined that PAO for the branching artery of right A1 could be performed with few complications. The size of the fusiform aneurysm was 2.6 × 2.7 × 1.7 mm, and a perforating branch was found at the origin of the branching artery of the right A1. Under general anesthesia, we guided the 6Fr FUBUKI dilator sheath (Asahi Intec Corporation, Seto, Aichi, Japan) by the right femoral artery approach, and implanted it in the right proximal internal carotid artery (ICA). We coaxially guided the Vecta71 (Stryker, Kalamazoo, MI, USA) and implanted it in the right ICA cavernous portion. Furthermore, we coaxially guided the Transform C 4 × 10 mm (Stryker) and implanted in the right ICA-top. Subsequently, we guided SL-10 straight (Stryker) with Synchro select guidewire (Stryker) and implanted SL-10 distal to the fusiform aneurysm (Fig. 1D). We performed coil embolization to the fusiform aneurysm of the right FPA from SL-10 with Target 360 Ultra and Tetra (Stryker). From the 3rd coil embolization, the coil partially penetrated into the aneurysm which was not contrasted (Fig. 1E), and it was not the extravasation. After embolization of a total of 5 coils, we confirmed that the distal portion from the fusiform aneurysm was not depicted and the perforating branch at the origin of the branching artery of right A1 was preserved (Fig. 1F). On the 2nd day of admission, diffusion-weighted magnetic resonance imaging (MRI) showed cerebral infarction in the territory of the right FPA (Fig. 2A), and so we determined that the responsible vessel of the fusiform aneurysm was the right FPA. Aspirin 100 mg was started on the same day to prevent infarction in the perforator territory. As expected, there were no abnormal neurological findings associated with the cerebral infarction. On the 7th day of admission, we performed cerebral angiography to check for cerebral vasospasm. There was no cerebral vasospasm, but the left extracranial ICA dissection was confirmed (Fig. 2B). In fact, head CT angiography on the admission day showed the dissection of the same lesion (Fig. 2C). Based on these findings, we determined that fusiform aneurysm of the FPA was most likely indicated by the dissection. We could not confirm the intimal flap of the right FPA from contrasted CT on the admission day because it was difficult to confirm the tomographic plane of the FPA on contrasted CT due to the running of FPA, and the diameter of the FPA made it difficult to confirm those findings on contrasted CT. However, caliber irregularities suspicious of pearl and string sign were seen before and after the fusiform aneurysm of the FPA (Fig. 1C), and these findings were considered supportive of the dissection. The patient had multiple cerebral artery dissections, and we conducted a close examination of the underlying diseases with fibromuscular dysplasia (FMD) and other conditions in mind. Blood tests were negative for various autoantibodies. Thoracoabdominal CT angiography showed no other obvious arterial dissection. Family history was also unclear. Frontal assessment battery (FAB) test performed postoperative had a score of 18/18, with no apparent findings suggestive of frontal lobe dysfunction. The motor paralysis of the left lower limb extremity improved over time; no apparent cerebral vasospasm or hydrocephalus occurred during the hospitalization, and the patient was discharged with modified Rankin Scale (mRS) 0 on the 27th day of admission. Aspirin was discontinued from the time of discharge.
Informed consent was obtained from the patient.
In Japan, VA and ACA are known to be the most common sites of cerebral artery dissection.2) It has been reported that the A2 segment accounts for 90% of ACA dissections, and there have been no previous reports of dissection of FPA.7,8) According to previous reports, 73% of ACA dissections resulted in cerebral infarction alone, 10% resulted in SAH alone, and 17% resulted in both cerebral infarction and SAH.1) In this case, SAH was caused by dissection of the FPA anomaly arising from the A1 segment. FPA usually arises from the proximal portion of A2, with very few reports of it arising from A1.9) It was reported that a vascular anomaly such as fenestration of the A1 segment was a high risk of saccular aneurysm at the proximal end of the A1 segment and these aneurysms have a high risk of rupture.10) However, we could not find reports that an anomaly branching was associated with the dissection. It was unclear whether the anomaly branching of the FPA was associated with the dissection and SAH, but the possibility that the anomaly branching was a risk for those vascular pathologies was considered. There have been reports of coil embolization of the saccular aneurysm in FPA and neck clipping of the saccular aneurysm in fronto-orbital artery (FOA) anomaly arising from A1, but there have been no reports of treatment of the fusiform aneurysm caused by the dissection of FPA arising from A1 by PAO as in this case (Table 1).3–6)
| Authors | Age/Sex | Site of aneurysm | Feature of aneurysm | Treatment |
|---|---|---|---|---|
| Hong et al. (1997)3) | 27/F | FOA arising from A1 segment | Saccular | Neck clipping |
| Aso et al. (2015)4) | 52/M | The common trunk of FOA and FPA arising from A1 segment | Saccular | Neck clipping |
| Ahmad et al. (2018)5) | 17/F | FPA arising from A2 segment | Saccular | Coil embolization |
| Nomura et al. (2022)6) | 48/F | Callosomarginal artery arising from A1 segment | Saccular | Neck clipping |
F, female; FOA, fronto-orbital artery; FPA, frontopolar artery; M, man
In this case, we determined it to be SAH associated with ruptured fusiform aneurysm in the right FPA anomaly arising from A1 based on cerebral angiography (Fig. 3) and the postoperative infarction site. Since the patient had a fusiform aneurysm and had a mild frontal headache 4 days prior to the onset of SAH, the aneurysm was considered to be most likely caused by the FPA dissection. Head CT on admission showed a right medial frontal hematoma, and we decided to perform PAO for right FPA because we considered that PAO for FPA was unlikely to cause worsening of the neurological findings. If there is a risk of worsening neurological findings with PAO, such as if the patient is left-handed, then PAO should not be performed and stenting is considered appropriate. In addition, the patient had the coexisting left extracranial ICA dissection. The patient had multiple cerebral artery dissections, and we conducted a close examination of the underlying diseases with FMD and other conditions in mind. Thoracoabdominal CT angiography showed no other obvious arterial dissection, including renal arteries, but the left extracranial ICA dissection was considered a possible finding suggestive of FMD. In addition, blood tests were negative for various autoantibodies. Other physical findings suggestive of Marfan syndrome or EhlersDanlos syndrome were not evident, nor was family history suggestive of hereditary disease. The outpatient follow-up continued with strict blood pressure control and MRI follow was continued.
We experienced a rare case of SAH associated with a ruptured fusiform aneurysm in the right FPA anomaly arising from the A1 segment. Moreover, this is the first reported case of the FPA dissection aneurysm treated by PAO.
The authors declare that they have no conflicts of interest.
