Successful endovascular treatment of a dissecting aneurysm of vertebral artery associated with double origin of the posterior inferior cerebellar artery

Introduction

Reports of developmental anomaly of double origin of the posterior inferior cerebellar artery (DOPICA) are rare, with an incidence of 1.45%.^1–7 The significance of DOPICA remains unclear, although it is sometimes associated with intracranial aneurysms.^2,3,6 In particular, a high rate of concurrence of DOPICA and vertebral artery dissecting aneurysm (VADA) or posterior inferior cerebellar artery (PICA) dissection has been reported.^4,7 Intracranial vertebral artery dissections initially presenting without subarachnoid hemorrhage (SAH) usually have a benign nature, and the incidence of recurrent ischemic stroke is low.^8–10 However, the optimal management has not been established, partly because of a possibility of subsequent SAH.

Case report

A 61-year-old woman had a preceding headache. The next day, she also had left neck pain and vomiting after a floating sensation. She presented to the emergency department of our hospital while she was almost fully conscious. She also claimed double vision when she looked straight ahead. Diffusion-weighted magnetic resonance imaging (MRI) of the head showed high signal intensity of the left lateral medulla (Figure 1(a)), and magnetic resonance angiography (MRA) showed poor visualization of the left vertebral artery (Figure 1(b)). A fresh infarction of the left medulla due to dissection of the left vertebral artery was suspected, and she was treated conservatively, not using antiplatelets or anticoagulants. However, on the morning following admission, she had transient loss of consciousness, while electrocardiogram showed running of premature ventricular contraction. Thereafter, she had worsening of headache, and subsequent stroke was suspected. OPEN IN VIEWER

MRI showed diffuse SAH with intraventricular hemorrhage in addition to the infarction of the left medulla (Figure 1(c)). Brain four-vessel digital subtraction angiography confirmed the diagnosis of dissection of the left vertebral artery (Figure 2(a) and (b)). Further, it revealed the double origin of the PICA and that the dissecting lesion largely involved an intracranial origin of the PICA, but not an extracranial origin. Internal trapping was chosen to treat the dissecting lesion as the extracranial channel was expected to supply the PICA territory. The procedure was performed under local anesthesia. The left vertebral artery was catheterized with a 5Fr-guiding catheter through the right femoral artery. A microcatheter was placed into the dissecting lesion, and nine coils were deployed to occlude the lesion. Postoperative angiogram showed patency of the left PICA through the proximal origin (Figure 2(c)). Although postoperative MRI showed small infarcts in the PICA territory probably due to emboli during the procedure (Figure 3), she almost fully recovered except for wooziness and left the hospital to return home. The follow-up angiography at six months after the procedure showed occlusion of intracranial vertebral artery and patency of the extracranial origin of PICA. OPEN IN VIEWER

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Figure 3.

Diffusion weighted image of postoperative magnetic resonance imaging showed high signal lesions in the territory of the posterior inferior cerebellar artery, suggesting fresh infarcts due to distal emboli during the procedure.

Discussion

DOPICA has been rarely reported in the literature, but is generally thought to occur because of persistence of the connection between the lateral spinal artery (LSA) and the PICA ² . Lasjaunias et al. described the role of the LSA in the developmental anatomy of the distal vertebral artery. ¹¹ They showed that anatomic variants such as the C1 and C2 origin of the PICA, duplication of the vertebral artery, double origin of the PICA at C1 and C2, or occipital artery origin of the PICA are related to variation in size and connection of the LSA. They also emphasized the importance of identification of the LSA in planning endovascular surgery. Siclari et al. later reviewed the normal and developmental anatomy of the cervical spinal arteries, and discussed the underlying mechanisms in detail. ¹² They proposed that some anatomic variants of vertebral artery and PICA origins are the result of variations in the development of the posterior spinal artery. Although the clinical significance of the PICA remains unknown, a high rate of association with cerebral aneurysms has been reported.^2,3,13 High concurrence rates of DOPICA and VADA/PICA dissection have been reported from Asian countries (Table 1),^4,14 and an additional anchor of the PICA to an atlantooccipital extradural vertebral artery site was suggested to increase the chance of stretching, compressing, or dissecting the vertebral artery or PICA. ⁴

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Table 1.

Characteristics of dissecting vertebral artery/posterior inferior cerebellar artery aneurysms associated with double origin of the posterior inferior cerebellar artery.

	Author	Age	Sex	Presentation	Side	Location	Treatment	Clinical outcome
1	Kwon et al., 2007 4	68	Female	SAH	Ipsilateral	PICA	Internal trapping	GR
2	Kwon et al., 2007 4	50	Female	SAH	Ipsilateral	VA	Internal trapping	GR
3	Kwon et al., 2007 4	NA	NA	SAH	Ipsilateral	VA	Internal trapping	GR
4	Kwon et al., 2007 4	NA	NA	SAH	Ipsilateral	PICA	Internal trapping	GR
5	Kwon et al., 2007 4	72	Male	SAH	Ipsilateral	PICA	Internal trapping	Death
6	Lee et al., 2011 5	43	Male	Headache	Contralateral	VA	Conservative	GR
7	Koh et al., 2012 7	56	Female	SAH	Ipsilateral	PICA	Surgical trapping	GR
8	Koh et al., 2012 7	42	Male	SAH	Ipsilateral	VA	Internal trapping	GR
9	Fan et al., 201114	58	Male	SAH	Ipsilateral	VA	Internal trapping	GR
10	Present case	61	Female	Ischemia to SAH	Ipsilateral	VA	Internal trapping	GR

The clinical course and prognosis of VADA are variable: it may present as a ruptured form, causing SAH, or as an unruptured form associated with ischemia or local symptoms. In the ruptured case, early surgical intervention is critical because of a high incidence of rebleeding and poor prognosis after rebleeding.^15–18 By contrast, the management of symptomatic intracranial unruptured (siu) VADA remains controversial. On one hand, the rate of recurrent ischemic attacks is low,^8,10 although several cases of siu VADA causing subsequent SAH have been reported.^19–24 To our knowledge, this is the first report of a patient with VADA associated with DOPICA who originally had ischemia and subsequently suffered from SAH. In fact, the rate of subsequent SAH of siu VADA in the Japanese population is as high as 3.4%, ²⁵ although that of non-Japanese populations was quite low. ¹⁰ Naito et al. suggested endovascular treatment for patients with VADA with relatively large or growing aneurysmal dilatations, and described the difficulty of predicting subsequent SAH in patients with siu VADA by angiographic findings. ¹⁹

The major advance of endovascular treatment with coils has made the treatment of VADA safer and easier, even in the acute phase of SAH.^26,27 Endovascular techniques of VADA can be divided into deconstructive and reconstructive. ²⁸ A deconstructive procedure can be safely performed if vital arterial branches are not involved in the segment of the vessel to be treated. However, the dissected segment cannot be occluded in patients with VADA involving PICA. That is why the treatment of VADA in them remains difficult, with a reported procedure-related morbidity of 16.7%. ²⁹ Reconstructive procedures should be performed using stent placement including stent-assisted coiling and flow diverter stent, when we have to preserve the parent artery. The risk of bleeding with conservative management and the risk of ischemic complications associated with endovascular treatment using deconstructive or reconstructive techniques should be carefully considered in determining the indications of VADA in each case. As far as we know, all patients who had ipsilateral vertebral artery/PICA dissecting aneurysms associated with DOPICA on the ipsilateral side eventually had SAH. It is possible that this reflects a publication bias, as DOPICA can be overlooked in unruptured VADA; cerebral angiography is not routinely performed in unruptured cases. However, the risk of ischemic complications in the treatment of VADA associated with DOPICA can be reduced by preserving the extracranially originating PICA. Accordingly, early endovascular internal trapping should be considered when the risk of subsequent hemorrhage cannot be ignored for a long lesion, such as that in our case, in the management of intracranial vertebral artery or PICA dissecting aneurysms.

Conclusion

DOPICA is a relatively rare anomaly and may present a risk factor for subsequent aneurysm development and rupture. Early endovascular intervention should be considered even in the treatment of unruptured intracranial DAVA associated with DOPICA, when it can be performed safely.