Abstract

BackgroundIsolated spinal aneurysms (ISAs) represent a rare etiology of subarachnoid hemorrhage (SAH). There are very few published reports of the rupture of an ISA, which has led to ongoing debate regarding the optimal therapeutic approach. We report a rare case of an isolated radiculomedullary artery aneurysm associated with SAH. Endovascular treatment was attempted but was unsuccessful. However, imaging confirmed that the aneurysm thrombosed relatively early following the procedure.

Case DescriptionA 59-year-old woman presented with a sudden headache and vomiting. Head computed tomography showed SAH with a thick hematoma in the posterior fossa. Initial angiography could not detect the source of bleeding, but follow-up angiography revealed an aneurysm ventral to the C5 spinal cord. Endovascular embolization was attempted but was terminated without placing embolizing material due to difficulty in guiding the microcatheter. Thrombus and shrinkage were observed on follow-up imaging, and complete occlusion of the aneurysm was observed on angiography.

ConclusionAlthough rare, manipulation during endovascular therapy likely caused thrombus formation, leading to occlusion of the aneurysm. Therefore, postoperative imaging follow-up is important even in cases of unsuccessful endovascular treatment.

Keywords: Isolated spinal aneurysm, Radiculomedullary artery, Subarachnoid hemorrhage, Thrombolization

INTRODUCTION

Subarachnoid hemorrhage (SAH) of spinal vascular origin is a rare occurrence, accounting for <1% of all cases of SAH reported in the literature.[ 16 ] Common causes of spinal aneurysms are related to arteriovenous malformation, arteriovenous fistula, aortic stenosis, and vasculitis.[ 9 ] Spinal artery aneurysms, defined as focal dilatations of the spinal arteries, are a rare cause of SAH. These lesions are uncommon and are frequently associated with spinal arteriovenous shunts (AVSs) due to the continuous high-flow blood dynamics. Specifically, spinal artery aneurysms without AVSs are sometimes found and are termed isolated spinal aneurysms (ISAs).[ 6 , 9 ] According to available data in the literature, ISAs are still unclear in terms of epidemiology, clinical features, and treatment strategies.[ 6 , 9 ] Treatment modalities for ISAs include conservative management, surgery, or endovascular intervention.

We report a case of a ruptured radiculomedullary artery aneurysm in which endovascular treatment was unsuccessful, and the aneurysm was occluded by postoperative thrombosis, together with a literature review.

CASE PRESENTATION

The patient was rushed to our hospital with a sudden onset of headache and vomiting. On arrival, the patient’s level of consciousness was Glasgow Coma Scale E3V5M6, and there was no focal neurological deficit except headache. Head computed tomography (CT) showed SAH in the posterior fossa. That indicated Grade II by the World Federation of Neurosurgical Surgeons, Hunt and Kosnik, and Fisher group 3 [ Figure 1a ]. No hemorrhage source could be identified by three-dimensional CT angiography (3D-CTA) and initial cerebral angiography. Enhanced magnetic resonance imaging (MRI) on day 3 showed an enhanced lesion ventral to the spinal canal at the C4 level of the cervical spine [ Figure 1b ]. 3D-CTA on day 4 showed a mass-like dilated vascular structure at the C4 level [ Figures 1c and d ]. T2 volume isotropic turbo spin-echo acquisition images on day 9 showed a nodular lesion along the anterior root of the fifth cervical nerve [ Figure 1e ]. Angiography was performed again on day 9, and the left vertebral artery (VA) angiogram showed no obvious source of bleeding. The right VA angiogram revealed that a tiny fusiform aneurysm was located in the radiculomedullary artery (RMA), which fed the anterior spinal artery at the C5 level of the cervical spine [ Figures 2a and b ]. No other vascular lesions were seen.

Figure 1:

(a) CT images on admission showing that diffuse subarachnoid hemorrhage is mainly located in the posterior cranial fossa. (b) Enhanced-MRI on day 3 in coronal plane showing an enhanced area (arrow) in the ventral side of the spinal canal. (c),(d) 3D-CT angiography (CTA) source images on day4 in axial plane and coronal plane showing the aneurysm (arrow) located intradural space. (e) T2-weighted volume isotropic turbo spin-echo acquisition (T2 VISTA)shows the aneurysm (arrow)along the anterior root of the fifth cervical nerve.

Embolization for this fusiform aneurysm was attempted to prevent rebleeding. The patient was treated under local anesthesia. A 5 French guiding catheter was inserted in the right VA, and a Marathon (eV3 Covidien, Irvine, CA, USA) with a 0.010-inch outer diameter microguidewire was placed in the RMA starting at level C5. It was reached to its proximal aneurysm [ Figures 2c and d ]. The tip of the marathon microcatheter was successfully guided into the proximal parent artery. However, it was hard to advance proximal to an aneurysm because of inadequate catheter support and tortuosity of the parent artery. We finally gave up the embolization. At the end of the procedure, we did not observe the obliteration of the aneurysm.

Figure 2:

(a), (b) Right vertebral angiograms in anteroposterior projection and lateral projection. A lobulated fusiform aneurysm (arrow) is seen at the right C5 RMA, which supplies the anterior spinal artery (arrowheads). Intraoperative images (c: anteroposterior view, d: lateral view) showing a microguidewire is inserted into the feeder of the C5 radiculomedullary artery (RMA).

On postoperative day (POD)3, CT revealed a high absorption and loss of contrast effect in the aneurysm, which indicates thrombosis [ Figures 3a and b ]. On POD-10, CT revealed that the aneurysm was reduced, and there was no contrast effect [ Figure 3c ]. On POD-14, MRI showed a mixed signal lesion suggesting subacute thrombus on T1-weighted images and it was concluded that the occlusion was due to thrombosis [ Figures 3d and e ]. The patient was discharged home with a modified Rankin Scale (mRS) of 0 on day 32. Angiography under general anesthesia on POD-73 revealed that the aneurysm had disappeared [ Figures 4a and b ]. The patient is currently an outpatient with mRS 0 and has had no recurrence 3 years after the attempt at embolization.

Figure 3:

(a) 3D-CT angiography (CTA) source images on post operative day (POD)-3 revealing a high-density are in the aneurysm (arrow) on non-contrast CT, (b) which lost contrast effect on contrast CT. (arrow) (c) 3D-CTA source image on POD-10 showing the reduction of aneurysm (arrow) without contrast. (d), (e) T1-weighted MRI on POD-14 showing mixed signal intensity (arrow) on axial plane and sagital plane.

Figure 4:

(a and b) Right vertebral arteriograms on postoperative day-73 showing the disappearance of the fusiform aneurysm at C5 (a: Anteroposterior view, b: Lateral view).

DISCUSSION

According to previous literature, ISAs generally involve the anterior spinal artery (ASA), posterior spinal artery, RMA, or radiculopial artery.[ 18 ] Contrast-enhanced CT is valuable in precisely determining the aneurysm’s location relative to the spinal cord and visualizing its relationship with the spinal canal. In this case, both 3D-CTA and the initial angiography failed to detect the aneurysm. We propose that a hematoma may have occluded the aneurysm due to its very small size.

Consequently, small aneurysms are frequently overlooked, with most reported cases measuring 3 mm or less in diameter.[ 1 ] A second angiogram of the right VA revealed a small mass-like staining in the RMA during the early arterial phase, which persisted into the late venous phase. No arterial branches were identified near the aneurysm, and the staining continued to drain into the ASA. No AVSs or abnormal veins were observed. According to previous reports, most ISAs are thought to result from dissection, often presenting with an irregular shape and contrast stagnation in the sac during the late venous phase.[ 1 , 4 ] In our case, the aneurysm was fusiform and located independently of arterial bifurcation, consistent with a dissecting aneurysm.

Ruptured ISAs have been managed using surgical intervention, endovascular embolization, or conservative approaches. However, as no standardized treatment guidelines exist for these lesions, the choice of treatment remains controversial. Furthermore, the epidemiology, optimal management strategies, occlusion rates, and outcomes are still largely unknown.[ 4 , 10 , 12 ] The surgical approach is more commonly employed in posteriorly localized aneurysms due to their dorsolateral and superficial location.[ 9 ] The mass effect of the aneurysm or the blood clot may be an indication of microsurgery.[ 2 ] Surgical procedures for ISAs in the ASAs are more challenging due to the high risk of spinal cord ischemia and the difficulty in surgically exposing the lesion. In particular, surgical access is difficult for ASAs aneurysms located at the upper cervical levels because of the narrow operative view. Therefore, endovascular or conservative management may be preferable for ISAs in the ASAs. Several authors have reported successful outcomes with conservative management, resulting in spontaneous healing of aneurysmal thrombosis and dissection.[ 1 , 4 , 7 , 13 , 14 , 15 , 17 ] Berlis et al. reported a case in which spontaneous healing of an aneurysm was found when surgery was performed 26 days after the onset. They concluded that conservative management may be appropriate.[ 1 ] For cases involving a small parent artery diameter, an aneurysmal type suggestive of a dissecting aneurysm, and the absence of spinal cord compression, conservative treatment may lead to spontaneous remission, making a wait-and-see approach a viable option. However, some patients have died from rebleeding despite conservative treatment. Henson and Croft reported a case of rebleeding 8 months after the initial onset.[ 5 ] Kocak et al. described a patient who died of rebleeding within 24 h of onset, despite surgery having been planned, highlighting the importance of prompt treatment to prevent rebleeding.[ 8 ] Geibprasert et al. also emphasized that early intervention is recommended due to the high rates of rebleeding and mortality.[ 3 , 9 , 14 ] Due to the limited availability of published reports on the management of ISAs, drawing definitive conclusions regarding the optimal therapeutic approach remains uncertain. Treatment should be carefully tailored to the specific circumstances of each case.

In our case, the ventral aspect of the spinal cord is fed by RMA, which is connected to the ASA. Because the aneurysm is located on the ventrolateral aspect of the spinal cord, it cannot easily be approached surgically. Hence, we scheduled the procedure for endovascular embolization. After several unsuccessful attempts, we discontinued the endovascular treatment. Following this failure, we initially planned to transition to open surgery. However, a preoperative contrast-enhanced CT re-evaluation of the aneurysm revealed findings suggestive of thrombosis. Consequently, we opted for conservative management. Manipulation of the guidewire and microcatheter during the procedure may have caused spasm and endothelial damage to the RMA, which subsequently induced thrombosis and led to the occlusion of the aneurysm. We closely monitored our patient and confirmed complete occlusion, and she has remained recurrence-free in the outpatient setting for 3 years. Although this is an extremely rare case, conservative management may be effective in cases of ISAs that have become thrombosed after attempted embolization. Regardless of the treatment method, postoperative imaging follow-up is important even in cases of unsuccessful endovascular treatment.

CONCLUSION

We experienced a very rare case of isolated radiculomedullary artery aneurysm with SAH. We attempted embolization therapy for the aneurysm and failed. Subsequently, the lesion thrombosed, and the patient made favorable progress. While this progress must be rare, the occlusion after attempted embolization emphasizes the importance of follow-up examination. It is anticipated that the accumulation and analysis of additional cases will clarify the natural history and treatment indications for ISAs with SAH.

Ethical approval

Institutional Review Board approval is not required.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation

The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.

Disclaimer

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.

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