Adult subarachnoid hemorrhage from vein of Galen aneurysmal malformation due to ruptured feeder aneurysm: A case report with long-term MRI review

Abstract

Adult hemorrhage from a previously treated vein of Galen aneurysmal malformation (VGAM) is exceedingly rare, and rupture of a flow-related feeder aneurysm has only been documented once in the adult case. We report a 20-year-old man with subarachnoid hemorrhage who presented with sudden headache. He had undergone palliative transarterial embolization (TAE) for choroidal-type VGAM during infancy for several times and had been followed annually with MRI at another institution. Digital subtraction angiography demonstrated two small feeder aneurysms, one presumed to have ruptured; additional embolization achieved complete occlusion of both aneurysms and a marked reduction in shunt flow. Retrospective review of serial MRIs showed progressive stenosis and eventual occlusion of the left transverse sinus, with first visualization of a feeder aneurysm one year prior to the rupture. This case represents only the second adult VGAM hemorrhage clearly attributed to a feeder artery aneurysm. Progressive venous sinus changes on follow-up MRI should prompt early angiographic re-evaluation and consideration of prophylactic treatment based on individual hemodynamic risk.

Introduction

Vein of Galen aneurysmal malformation (VGAM) accounts for approximately 1% of all intracranial vascular malformations [[1], [2], [3], [4]], with only a few cases -approximately up to five- reported annually in Japan [5]. The choroidal type of VGAM is characterized by a primitive vascular architecture, in which the aneurysmal sac is connected to a network of arteries within the cistern [2,6]. This subtype poses significant challenges to curative treatment, and many cases are managed palliatively with repeated transarterial embolization (TAE) during follow-up.

Currently, there is no established evidence regarding the optimal timing for additional interventions in such cases, and treatment decisions are often made at the discretion of the attending physician based on the individual clinical course.

Here, we report a case of a 20-year-old subarachnoid hemorrhage patient who had undergone multiple TAEs against VGAM since infancy and was under follow-up at another institution. Through this case, we propose follow-up strategies for patients with choroidal type VGAM treated palliatively with TAE.

Case presentation

The patient is 20-year-old male who was diagnosed with a VGAM during infancy due to symptoms of heart failure. He underwent a total of four palliative TAE procedures during infancy and childhood at another hospital. Since then, he had been under regular follow-up with annually conducted MRI at the same hospital. At the age of 20, he suddenly developed severe headache and vomiting and was brought to our hospital by ambulance. On arrival, his blood pressure was 147/85 mmHg, and heart rate was 110 beats per minute. His level of consciousness was Glasgow Coma Scale (GCS) E3V4M6, indicating confusion. There was no anisocoria, motor weakness, or sensory deficits.

Noncontrast head CT revealed diffuse subarachnoid hemorrhage classified as Fisher group 3, along with marked ventricular enlargement (Fig. 1A and B). High-density areas suggesting calcifications were observed within the subcortical white matter, brain parenchyma, and dilated venous walls. (Fig. 1B) CT angiography revealed a choroidal-type vein of Galen aneurysmal malformation (Fig. 1C).

Fig. 1.

(A, B) Noncontrast head CT shows diffuse subarachnoid hemorrhage (Fisher group 3), marked ventricular enlargement, and calcifications along dilated venous walls. (C) CT angiography revealed a choroidal-type vein of Galen aneurysmal malformation.

Digital subtraction angiography under general anesthesia demonstrated numerous feeding arteries, including anterior pericallosal (subforniceal) arteries, thalamoperforators, choroidal arteries, quadrigeminal arteries, posterior cerebral arteries, and meningeal arteries (Fig. 2A–F).

Fig. 2.

Pretreatment digital subtraction angiography. (A, B) Left internal carotid artery (ICA) angiography, AP and lateral views. (C, D) Right ICA angiography, AP and lateral views. (E, F) Left vertebral artery (VA) angiography, AP and lateral views. (G) 3D rotational angiography of the left VA shows a feeder aneurysm on the right quadrigeminal artery (white arrowhead). (H) Cone-beam CT confirms the feeder aneurysm (white arrowheads).

Shunt flow drained via a developed falcine sinus into the right transverse sinus through the superior sagittal sinus, while the left transverse sinus was occluded.

3D rotational angiography with image reconstruction revealed aneurysms on the right quadrigeminal artery and the left anterior pericallosal (subforniceal) artery, both of which were feeding arteries. Based on the distribution of the subarachnoid hemorrhage, the aneurysm on the right quadrigeminal artery was presumed to be the source of bleeding (Fig. 2G and H).

Antihypertensive treatment and mild sedation were initiated immediately, and additional TAE was conducted on the 4th day of hospitalization (Fig. 3).

Fig. 3.

(A) Pretreatment lateral view of bilateral ICA angiography. (B) Pretreatment AP view of left VA angiography shows feeder aneurysm on the right quadrigeminal artery (white arrowhead). (C) Posttreatment lateral view of bilateral ICA angiography shows significant reduction in the shunt flow. (D) Posttreatment AP view of left VA angiography shows obliteration of the feeder aneurysm.

Under general anesthesia with endotracheal intubation in the angiography suite, two 6Fr. sheaths were introduced via the bilateral femoral arteries. Two 6Fr. guiding catheters were advanced into the right and left internal carotid arteries. Six terminal feeders were catheterized using flow-directed microcatheters, including Magic 1.5Fr. microcatheters (Balt, France) and Marathon 1.5Fr. microcatheters (Medtronic, U.S.), in combination with microguidewires. Each feeder was embolized with an NBCA (n-butyl cyanoacrylate) and Lipiodol mixture. Embolized feeders and mixture concentrations are shown below.

• 1.Left anterior pericallosal (subforniceal) artery (50% NBCA).
• 2.Left anterior thalamoperforating artery (33% NBCA).
• 3.Left lateral posterior choroidal artery (33% NBCA).
• 4.Left parieto-occipital artery from the posterior cerebral artery (33% NBCA).
• 5.Left quadrigeminal artery (33% NBCA).
• 6.Right anterior pericallosal (subforniceal) artery (33% NBCA).

After the embolization of 6 major feeders shown above, control angiography demonstrated a significant reduction in the shunt flow and obliteration of the feeder aneurysms while preserving adjacent cortical arteries and the falcine sinus. The patient tolerated the procedure well, with prompt arousal from general anesthesia and no new neurological deficits were detected.

Postoperative MRI showed a small left occipital lobe infarction, which was asymptomatic. Although no clear deterioration in neurocognitive function was observed, mild pre-existing intellectual disability was suspected based on our examination. A follow-up MRI showed no evidence of cerebral vasospasm, and the patient was discharged home with no neurological deficit 10 days after the procedure.

After our treatment, we obtained the full follow-up records and image data from the hospital where the patient had been monitored and reviewed them. Annual MRI had been performed since infancy, except between 16 and 18 years of age (2020–2022), when surveillance was interrupted by the COVID-19 pandemic. The MRI performed at 15 years showed neither a feeder aneurysm nor stenosis of the left transverse sinus. The MRI performed at 19 years revealed a small, suspicious feeder aneurysm in the right quadrigeminal cistern and emerging stenosis of the left transverse sinus. The most recent follow‑up MRI, obtained at 20 years—approximately one month before the onset of subarachnoid hemorrhage—demonstrated complete occlusion of the left transverse sinus (Fig. 4).

Fig. 4.

Retrospective review of external follow-up MRI studies (A) MR angiography at age 15 shows no feeder aneurysms. (B) MR angiography at age 19 shows small feeder aneurysm in the right quadrigeminal cistern. (C-E) FLAIR and MR venography at ages 15, 19, and 20 demonstrate progressive narrowing and, by age 20, complete occlusion of the left transverse sinus. (white arrowheads).

Discussion

VGAM is a rare congenital cerebral vascular malformation, typically diagnosed and treated during infancy or early childhood due to its hemodynamic consequences. Intracranial hemorrhage in adulthood is exceedingly rare. Strowitzki et al. reported a 27-year-old woman who presented with subarachnoid hemorrhage [7], whereas Gupta et al. described two young adults—a 21-year-old man with intraventricular hemorrhage and a 21-year-old woman with subarachnoid hemorrhage [4]. All these cases underwent digital subtraction angiography followed by transarterial embolization; however, none of the reports documented the presence of feeder aneurysms.

The present case illustrates several clinically important aspects. First, the patient had been under long-term MRI follow-up, during which progressive narrowing and eventual occlusion of the left transverse sinus were observed. Retrospective review also revealed the emergence of micro feeder aneurysm one year prior to the hemorrhagic event, although these findings had gone undetected at the time. This suggests that, even in clinically stable VGAM patients, vascular remodeling and shunt dynamics may evolve slowly and silently over many years, ultimately leading to aneurysm formation and risk of rupture.

In patients with dural arteriovenous fistulas, progressive stenosis of the draining vein is known to result from intimal injury and thrombus formation caused by chronic arterialized flow and hemodynamic stress [8]. In the present case, it is presumed that a similar mechanism led to thrombus formation and subsequent occlusion of the left transverse sinus. The same hemodynamic stress may also contribute to the formation of feeder aneurysms, which are rare but recognized complications of VGAM. These aneurysms are typically attributed to prolonged high-flow shunting, resulting in focal weakening of the arterial wall in feeding vessels. In our patient, aneurysms were identified on both the right quadrigeminal artery and the left subforniceal artery, with the former presumed to be the bleeding source based on SAH distribution.

Although MR angiography and conventional MRI are routinely used in VGAM follow-up, they may lack the spatial resolution to detect small aneurysms, especially when located in deep or tortuous vessels. In this case, the aneurysms were only identified on cerebral angiography at the time of hemorrhage.

Currently, there is no established consensus regarding the optimal timing of angiographic re-evaluation or additional embolization in VGAM patients under long-term follow-up. Our findings suggest that, in patients with partially treated VGAMs, progressive changes detected on annual MRI―such as the development or progression of venous sinus stenosis, worsening venous congestion, or alterations in cerebral flow dynamics−should be considered as a “red flag” and prompt reconsideration of cerebral angiography, even in asymptomatic individuals. Once feeder aneurysms are identified, prophylactic embolization may be warranted to mitigate the risk of future hemorrhage.

To our knowledge, there is only one report that has described an adult-onset hemorrhagic presentation of VGAM with an associated feeder aneurysm as a potential bleeding source [9]. However, in that report, the VGAM case with a feeder aneurysm arising from the proximal posterior cerebral artery was presented only as a single example within a figure as part of a series focusing on feeder aneurysms, and no detailed information regarding patient age, sex, clinical presentation, or longitudinal imaging follow-up was provided. In this context, our case appears to be the first to clearly demonstrate de novo formation and progression of a feeder aneurysm as the presumed cause of subarachnoid hemorrhage. This case therefore adds to the limited literature and emphasizes the importance of continued vigilance in long-term survivors of VGAM, even when they remain clinically asymptomatic.

Conclusion

This case highlights the potential for silent hemodynamic alterations and delayed aneurysm formation in long-term survivors of partially treated VGAM. MRI findings such as venous sinus stenosis or occlusion may warrant further angiographic evaluation, even in asymptomatic patients, and additional treatment should be considered based on individual hemodynamic risk.

Patient consent

Written informed consent for publication of this case report and accompanying images was obtained from the patient. All potentially identifying information has been removed to ensure patient anonymity.