Targeted endovascular treatment of haemorrhagic posterior fossa proliferative angiopathy

Abstract

Cerebral proliferative angiopathy (CPA) is a rare vascular abnormality and separate from “classical” brain arteriovenous malformations. Haemorrhage due to proliferative angiopathy is rarely reported. We describe the clinical features, imaging findings and targeted endovascular management for a 12-year-old boy having proliferative angiopathy of the posterior fossa presenting with haemorrhage. Targeted endovascular embolisation in CPA is not previously described in the literature. The optimal treatment options for haemorrhagic CPA are debatable, and we wish to highlight the role of targeted treatment for culprit focal lesion demonstrable on imaging.

Background

Haemorrhage in the posterior fossa cerebral proliferative angiopathy (CPA) is rarely described. Treatment options in CPA are usually conservative in view of diffuse angioarchitecture of the lesion interspersed with normal intervening brain parenchyma. Definitive targeted treatment options including endovascular methods have not been widely reported in the management of haemorrhagic CPA.

Case presentation

A 12-year-old boy presented with a history of sudden severe headache, vomiting, and neck pain. There was no history of fever, seizures, loss of consciousness or head injury. On examination, he was drowsy, obeying commands and no neck stiffness was noted. Sensory, motor system and speech were intact.

Investigations

Computed tomography (CT) of the brain showed parenchymal haemorrhage in the cerebellum along the right hemisphere and vermis with intraventricular extension causing dilatation of the supratentorial ventricular system (Figure 1(a)). Subsequent cerebral angiography showed diffuse, ill-defined vascular blush in the posterior fossa with arterial feeders from the bilateral posterior cerebral, superior cerebellar, posterior and anterior inferior cerebellar arteries. There was early venous draining into the superior vermian vein and cerebellar veins which were further draining into the superior sagittal sinus and torcula (Figures 1(b) and (c)). The arterial feeders, as well as the early draining veins, were not prominent and they were disproportionately smaller as compared to the size of the nidus. No abnormal transdural arterial supply was identified from the external carotid artery and vertebral artery branches. These findings on angiography were in favour of the diagnosis of infratentorial proliferative angiopathy. Additionally, an arteriovenous (AV) fistula and a flow-related aneurysm measuring 3 × 2 mm was also noted in the right distal anterior inferior cerebellar artery (AICA) just proximal to the fistulous site (Figure 1(b)). The location of the flow-related aneurysm was close to the site of cerebellar intraparenchymal haemorrhage, probably explaining the source of the bleed (Figure 1(d)).

Figure 1.

Non-contrast axial computed tomography image (a) showing intraparenchymal haemorrhage in cerebellar hemisphere and cerebellar vermis extending into the fourth ventricle. Cerebral angiography arterial and capillary phase images ((b) and (c)) showing ill-defined diffuse nidus in posterior fossa fed by arteries of posterior circulation with early draining veins as well as right distal anterior inferior cerebellar artery (AICA) aneurysm. Intraprocedural XperCT axial contrast image depicting the aneurysm (d) and the superselective microcatheter injection (e) of the right distal AICA showing the aneurysm and arteriovenous fistula.

Treatment

Endoscopic third ventriculostomy was performed through the right frontal approach for managing the hydrocephalus. The definitive treatment options including surgery and radiosurgery may not be feasible in the index case in view of intermingled normal brain parenchyma within the lesion. As the source of bleeding could be seen on digital subtraction angiography (DSA) and the patient was symptomatic from that lesion, the decision for targeted endovascular embolization of the aneurysm and the feeding AV fistula was considered. A Neuron 6Fr, 0.070-inch guiding catheter (Penumbra Inc, Alameda, CA, USA) was placed in the distal V3 segment of the left vertebral artery. A Marathon microcatheter with Mirage .008-inch guidewire (Medtronic, Minneapolis, MN, USA) was placed coaxially through the guiding catheter and navigated superselectively into the distal right AICA just proximal to the feeding artery aneurysm. Superselective injection from the microcatheter clearly depicted the AV fistula and associated flow-related aneurysm fed by the AICA (Figure 1(e)). The microcatheter was flushed initially with 0.6 ml of dimethyl sulfoxide and slow injection of Onyx 18 (Medtronic, Minneapolis, MN, USA) at the rate of 0.15–0.20 ml/minute to occlude the feeding artery aneurysm and the AV fistula. Control angiogram showed complete obliteration of the right AICA aneurysm and AV fistula (Figure 2(a)). Intraprocedural XperCT brain was performed following the embolisation procedure which showed the Onyx cast of the right AICA aneurysm (Figure 2(b)).

Figure 2.

Left vertebral artery check angiogram (a) after Onyx embolisation demonstrating complete obliteration of the aneurysm and arteriovenous fistula of the right distal anterior inferior cerebellar artery (AICA). Intraprocedural XperCT image (b) showing Onyx cast of the right AICA. Follow-up magnetic resonance imaging (MRI), axial susceptibility weighted image (c) showing the focal area of blooming corresponding to thrombosed right AICA aneurysm and MR angiogram coronal maximum intensity projection image (d) showing patent proximal segment of right AICA.

Outcome and follow-up

No new neurological deficit developed and the patient showed progressive improvement in sensorium during the post-procedure period and became actively ambulant. He was discharged in a stable neurological condition and remained asymptomatic for the next six months. Follow-up magnetic resonance imaging after six months (Figure 2(c)–(e)) revealed abnormal flow voids traversing cerebellar parenchyma with a focal area of blooming in the region of the thrombosed right AICA aneurysm and patent proximal segment of the right AICA.

Discussion

CPA is a distinct form of congenital vascular anomaly with a low occurrence. It is also known as “diffuse nidus” or “holohemispheric giant cerebral arteriovenous malformation (AVM)” and is different from classical brain AVMs.^1,2 CPA comprises 3.4% of all brain AVMs and the right cerebral hemisphere (45%) is the commonest site in which the decreasing order of lobar involvement are temporal, frontal, parietal and occipital lobes. Infratentorial involvement of CPA is seen in 22% of patients.³ CPA patients are usually young females who commonly present with epilepsy (45%), headaches (41%), and progressive neurological deficits (16%) or haemorrhage (12%). Even though haemorrhage is rare in CPA, when it occurs, the risk of recurrence is higher. Twelve per cent of CPA patients present with intracranial haemorrhage with recurrence of haemorrhage in two-thirds of them.³

The salient angiographic features described by Lasjaunias et al.³ for differentiating CPA from “classical” brain AVMs include: non-focal angiogenetic activity in the form of extensive transdural supply both to healthy and pathological tissues with proximal stenosis of the feeding arteries, absence of dominant feeders to the large-size nidus or flow-related aneurysms, the presence of capillary angioectasia and smaller veins in comparison with size of the nidus. Even though AV shunting has been classically described in CPA, neither AV fistula nor flow-related aneurysm was mentioned in such lesions,³ and they are considered unusual findings in CPA. The index case is unique as the patient was having haemorrhagic infratentorial CPA with the rarer presentation of flow-related aneurysm as a culprit lesion. Aggressive interventions including surgery, radiosurgery, and embolisation for complete eradication of the malformation are not advisable as they pose the risk of permanent neurological deficit due to the involvement of intermingled normal brain tissue. Other treatment options including synangiogenesis and calvarial burr hole creation have been tried in CPA to increase the cortical blood supply and ameliorate ischaemia.^4,5 In symptomatic patients with haemorrhage, the culprit lesion that is identified at angiography can be treated either by surgery or by the endovascular method. Even partial embolisation of fragile angioarchitecture by endovascular means is sufficient in controlling disabling symptoms.³ In our patient, there was a fragile area in the form of a flow-related aneurysm identifiable on DSA, making target embolisation a suitable treatment option.

Conclusion

Haemorrhage in CPA is uncommon. Angiography may be helpful in delineating the focal culprit lesion in haemorrhagic CPA. Targeted endovascular therapy can be a useful treatment option for select patients having an angiographically demonstrable and accessible culprit lesion.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.