Multiple small branch retinal arteriolar occlusions following coil embolization of an internal carotid artery aneurysm.

A 41-year-old male was referred from the neurosurgery department with visual disturbance immediately following coil embolization of a distal internal carotid artery aneurysm. On initial fundus examination, diffuse retinal opacification sparing the papillomacular bundle area was observed in his right eye. Optical coherence tomography showed inner retinal edema, and fluorescein angiography showed delayed arterial filling and multiple small arteriolar obstructions in that eye. After 2 weeks, although the inner retinal edema and retinal opacification improved, small arteriolar occlusions were still present. The small arteriolar occlusion-related perfusion defect persisted until the 6-month follow-up. Neurosurgeons should be aware of the possibility of iatrogenic retinal artery occlusion when they perform coil embolization. Moreover, long-term follow-up may be necessary to detect any ischemic complications, as these postprocedural retinal artery occlusions tend to be poorly reperfused.

Intracerebral vascular selective embolization has been widely used in the treatment of intracerebral vascular pathologies such as vascular tumors, malformations, and aneurysms. In particular, endovascular coiling of a ruptured intracranial aneurysm shows good outcomes with a lower rate of complications such as morbidity and decreased risk of epilepsy.[1] Currently, embolization procedures are mainly performed using a detachable coil technique because of its effectiveness for small aneurysms.[2] However, it has been reported that this technique carries the risk of ophthalmologic complications.[345] Herein, we report a case of multiple small retinal arteriolar occlusions following coil embolization.

Case Report

A 41-year-old male was referred from the neurosurgery department with visual disturbance in his right eye following coil embolization of a distal internal carotid artery (ICA) aneurysm. He had undergone coil embolization for a ruptured aneurysm of the anterior communicating artery 6 months earlier. Recently, another aneurysm was found at the right distal ICA after which he underwent prophylactic coil embolization using a detachable coil [Fig. 1].

Figure 1

Magnetic resonance angiography images obtained before and after coil embolization of an internal carotid artery aneurysm. The aneurysm was well sealed following coil embolization (arrows)

The embolization procedure was completed without any adverse events. However, the patient experienced a large visual field defect in his right eye immediately after the procedure. On initial ophthalmic evaluation, visual acuity was 20/20 in both eyes. Pupils were reactive; however, a mild relative afferent pupillary defect was observed in his right eye. On anterior segment examination, no abnormal findings were observed in both eyes. On fundus examination, diffuse retinal opacification sparing the papillomacular bundle area was observed in his right eye. Fluorescein angiography showed delayed arterial filling and multiple small branch retinal arteriolar obstructions in his right eye [Fig. 2a, arrows]. In addition, tortuosity and mild leakage suggestive of endothelial damage were observed in the inferior temporal branch retinal artery [Fig. 2a, arrow heads]. Optical coherence tomography also revealed inner retinal edema and hyperreflectivity on the temporal side of the macula [Fig. 2f]. Superior and inferior arcuate scotomas sparing the center field were observed in his right eye on the visual field test [Fig. 2k]. The left eye showed normal appearance, and no abnormalities were found on fluorescein angiography or optical coherence tomography. Two weeks later, retinal opacification had improved, and inner retinal edema had decreased [Fig. 2g]. On fluorescein angiography, perfusion had improved, albeit not completely, and inferior temporal arterial tortuosity had also improved [Fig. 2b]. Visual acuity in the right eye was 20/25, and there were no changes in the visual field [Fig. 2l]. Retinal opacification gradually improved, and temporal inner retinal thinning ensued [Fig. 2h–j]. His final visual acuity was 20/25 in his right eye. Although retinal perfusion improved, small arteriolar obstructions and capillary nonperfusion persisted [Fig. 2c–e].

Figure 2

Serial fluorescein angiography (a-e), optical coherence tomography (f-j), and visual field test (k and l) results of the patient suffering branch retinal artery obstruction following internal carotid artery coil embolization. Multiple arterial obstructions in his right eye ([a-e] arrows) were revealed. Vascular tortuosity and mild perivascular leakage were observed in the inferotemporal arterial branch ([a] arrowheads)

Discussion

In our case, the patient's initial central vision was relatively well preserved at 20/20 because of macular sparing. Hayreh et al.[6] reported that, in eyes with permanent branch retinal artery occlusion, the visual acuity of 74% of eyes examined within 7 days of onset was 20/40 or better. Therefore, clinicians always should suspect retinal artery occlusions in cases of blurred vision with fair visual acuity following neurologic endovascular procedures.

To the best of our knowledge, there have been only four cases of branch retinal artery occlusion following coil embolization of intracranial aneurysms.[345] In contrast to previous cases, multiple small arteriolar obstructions sparing the fovea center were found in our case. In addition, incomplete reperfusion was found on fluorescein angiography even after 6 months of the first event. Although it is known that ischemic complications are less common in branch retinal artery occlusion than in central retinal artery occlusion,[7] embolic events after procedures which are performed near the ophthalmic artery are expected to increase the risk of ischemic complications such as retinal neovascularization due to a large number of embolic occlusions and low reperfusion rate.

There are only a few reports on the risk of postprocedural thromboembolic events after coil embolization. Nagahata et al. reported on the factors that increase procedural thromboembolic events in patients with unruptured paraclinoid ICA aneurysm treated by coil embolization.[8] They concluded that withdrawal of an undetached coil from the aneurysm is the only factor that increases thromboembolic events. In our case, coil embolization was performed twice, once for ruptured aneurysm of the anterior communicating artery, and once for unruptured aneurysm of the paraclinoid ICA. Thus, our case may have harbored the increased risk of embolization complications.

Conclusion

Neurosurgeons should always be aware of the possibility of iatrogenic retinal artery occlusion when they perform coil embolization and be careful to choose proper coil to avoid withdrawal of coil. A thorough systemic workup for any hematologic or lipid disorders and ophthalmologic evaluations including fundus examination, visual field assessment, color vision should be conducted before and after endovascular procedures. In addition, long-term follow-up may be necessary to reveal the presence of ischemic complications, as these postprocedural retinal artery occlusions tend to be more poorly reperfused.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.