Internal carotid artery stenosis with persistent primitive hypoglossal artery treated with carotid artery stenting: A case report and literature review

Abstract

Persistent primitive hypoglossal artery (PPHA) is a persistent carotid-basilar anastomosis. It rarely remains at birth. It occasionally may be a risk for ischemia and embolic infarction to the posterior cerebral circulation, especially in patients with carotid stenosis proximal to the origin of persistent primitive arteries. We describe a case of a 60-year-old woman with asymptomatic internal carotid artery (ICA) stenosis and ipsilateral PPHA successfully treated by carotid artery stenting (CAS). A few cases of CAS for ICA stenosis with PPHA have been reported, but the strategy and methods in each case were different because of its unique anatomy and hemodynamics. It is essential to prevent distal embolisms and preserve blood flow at the territory of both the ICA and PPHA. The protection method should be selected carefully. We review the literature and discuss appropriate treatment strategies.

Introduction

Persistent primitive hypoglossal artery (PPHA) is a type of persistent carotid-basilar anastomosis. The estimated prevalence of PPHA is reported to be 0.1–0.25%.¹ The PPHA is important for blood supply to the basilar artery (BA). Hence, it occasionally may be a risk for ischemia and embolic infarction to the posterior cerebral circulation, especially in patients with carotid stenosis proximal to the origin of persistent primitive arteries.^2–5

Although a few case reports of carotid artery stenting (CAS) for internal carotid artery (ICA) stenosis with ipsilateral PPHA have been reported, the treatment strategy and methods differ in each case.^2–4,6,7 CAS for such cases often is an atypical and complicated procedure because of its unique anatomy and hemodynamics. It is essential to prevent distal embolisms and preserve blood flow at the territory of both the ICA and PPHA. The protection method should be selected carefully.

In the present report, we describe a case of ICA stenosis with ipsilateral PPHA that was successfully treated by CAS. Furthermore, we review the literature and discuss appropriate treatment strategies.

Case report

A 60-year-old woman presented to our hospital for the treatment of asymptomatic left ICA stenosis. Computed tomography (CT) angiography showed severe stenosis in the left ICA, as well as calcification. The ipsilateral PPHA branched from the ICA at the C2 vertebral body level. The PPHA passed through the left hypoglossal canal and merged into the BA (Figure 1). Maximum intensity projection (MIP) images of time-of-flight magnetic resonance angiography (TOF-MRA) and T1-weighted black-blood (BB) imaging did not show a high-intensity signal at the stenotic lesion (Figure 2).

Figure 1.

MIP images of CT angiography showing severe ICA stenosis with calcification (a), and the passage of the PPHA (arrow) through the left hypoglossal canal (b). Three-dimensional (3D)-RA showing severe stenosis of the left ICA, as well as branching of the ipsilateral PPHA (arrow) from the ICA (arrow head) at a point distal to the stenotic lesion. The ipsilateral PPHA is merged into the BA ((c) A-P view and lateral view).

BA: basilar artery; CT: computed tomography; MIP: maximum intensity projection; RA: rotational angiography; ICA: internal carotid artery; PPHA: persistent primitive hypoglossal artery; BA: basilar artery; A-P: antero-posterior.

Figure 2.

MIP image of TOF-MRA showing severe ICA stenosis and a high-intensity signal-negative plaque (a). T1-weighted BB-magnetic resonance imaging showing an isointense plaque (b).

BB: black-blood; ICA: internal carotid artery; MIP: maximum intensity projection; MRA: magnetic resonance angiography; TOF: time-of-flight.

Cerebral angiography showed 80% stenosis of the left ICA, as measured by the North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria.⁸ The stenosis did not extend to the PPHA, and was localized to the carotid bifurcation. The right vertebral artery (VA) was hypoplastic and the left VA was narrow (Figure 3); hence, the main supply of the BA was believed to be the PPHA.

Figure 3.

Left CCAG showing 80% stenosis of the left ICA (arrow head), measured by the NASCET criteria,⁸ as well as branching of the PPHA (arrow) from the ICA at a point distal to the stenotic lesion ((a) lateral view). Intracranial left CCAG simultaneously showing the ICA and BA. The left A1 appears hypoplastic and the anterior cerebral artery is not visualized ((b) A-P view and lateral view). The right VA appears hypoplastic, and the left VA is visualized and merged into the BA (c).

BA: basilar artery; CCAG: common carotid angiogram; NASCET: North American Symptomatic Carotid Endarterectomy Trial; VA: vertebral artery; ICA: internal carotid artery; PPHA: persistent primitive hypoglossal artery; BA: basilar artery; A-P: antero-posterior.

The patient was scheduled to undergo CAS for the prevention of future ischemic stroke under local anesthesia and moderate sedation. The patient was pretreated with clopidogrel (75 mg) and cilostazol (200 mg). Systemic unfractionated heparin was administered during the procedure to achieve an activated coagulation time of >275 seconds. A 9-Fr Optimo balloon guiding catheter (Tokai Medical Products, Aichi, Japan) was advanced into the left common carotid artery (CCA). The ischemic tolerance of the posterior circulation was believed to be acceptable as the left VA could be visualized slightly. A GuardWire plus System (Medtronic, Minneapolis, MN, USA) was advanced into the distal ICA and positioned at a point proximal to the origin of the PPHA, and served as distal balloon protection. Thereafter, flow reversal to the left femoral vein was performed, along with inflation of the proximal balloon. Furthermore, flow arrest was achieved with inflation of the proximal and distal balloon.

After atropine administration, pre-dilation was performed at the stenotic lesion by using a Jackal RX (3.5 × 20 mm; St. Jude Medical, St. Paul, MN, USA). In addition, a Carotid Wallstent (8 × 21 mm; Boston Scientific, Natick, MA, USA) was deployed. After appropriate device deployment, post-dilation was performed using a Sterling (4.0 × 20 mm; Boston Scientific, Natick, MA, USA). After confirming that no residual debris was present following the aspiration of accumulated blood, the proximal and distal balloons were deflated. The occlusion time with the proximal and distal balloon was 18 minutes. Complete coverage of the stenotic lesion was obtained by stenting (Figure 4). The results of the neurological examination did not change during the procedure. The patient’s postoperative clinical course was uneventful.

Figure 4.

A proximal occlusion balloon guiding catheter is inserted into the common carotid artery, and a distal balloon protection is placed in the ICA at a point proximal to the origin of the PPHA. Flow arrest was achieved with inflation of the proximal and distal balloon protection device. Pre-dilation of the stenotic lesion is performed via balloon angioplasty (a). Postoperative CCAG showing the restoration of the stenosis (b).

CCAG: common carotid angiogram; ICA: internal carotid artery; PPHA: persistent primitive hypoglossal artery.

Discussion

The PPHA is a rare anatomical anomaly.¹ Patients with PPHA may be completely asymptomatic, and this condition is usually detected incidentally. In most cases, it is an important component of blood supply to the vertebrobasilar circulation as the VA is often poorly developed in such cases.³ Some reports have indicated the presence of cerebral ischemia in the posterior circulation due to ICA stenosis with the PPHA.^2–5 To prevent a future ischemic stroke, carotid endarterectomy (CEA) was performed in such cases.^9–11 However, CEA may be difficult as the bifurcation of the PPHA itself may be located at a high level, and a Y-shaped shunt system is needed to preserve blood supply to the territory of both the ICA and the PPHA.¹¹

Recently, the common use of embolic protection in CAS has contributed to a low incidence of perioperative complications.¹² Hence, CAS, with an appropriate protocol and protection, may be an effective method in such cases. The previously reported cases of CAS for ICA stenosis with ipsilateral PPHA are summarized in Table 1.^2–4,6,7 In the CAS procedure, the modified Parodi’s method with single-distal protection under the flow reversal system,⁷ single-distal balloon protection or double-distal filter protection without proximal protection,^3,6 a Gore Flow-Reversal System (WL Gore and Associates, Flagstaff, AZ, USA) with occlusion of the proximal and distal ICA,⁴ and Parodi’s method using the Mo.Ma device (Invatec, Roncadelle, Italy)² have been reported. In all these cases, CAS was performed without any complications. However, these methods have certain disadvantages, such as the need for the placement of two guiding catheters in the CCA,⁷ the need for the crossing of a double-distal embolic protection device through the severe stenotic lesion,⁶ and the possibility of an incomplete flow reversal system.²

Table 1.

Literature review of the CAS for the ICA stenosis with PPHA.

Authors, year	Symptom	Stenotic lesion	Embolic protection methods	Vertebral Artery	Pcom	Anesthesia	Embolic events	Outcome
Kanazawa et al.,7 2008	Syncope	Lt. ICA stenosis (proximal to the origin of the PPHA)	Modified Parodi’s method using two GCs and single-distal balloon protection at the PPHA (flow reversal in one direction in the ICA)	Bil. Absent	NV	ND	None	Good
Nii et al.,3 2010	TIA	Lt. ICA stenosis (proximal to the origin of the PPHA)	Single-distal balloon protection at the ICA proximal to the origin of the PPHA	Rt: absent Lt: hypoplastic	NV	GA	None	Good
Silva et al.,6 2013	TIA	Extension of the Rt. ICA stenosis to the origin of the PPHA	Double-distal filter protection at the ICA and PPHA	ND	ND	GA	None	Good
Eller et al.,4 2013	Ischemia	Rt. ICA and PPHA stenosis (tandem lesion)	Gore Flow-Reversal system (flow reversal in one direction in the PPHA)	Rt: occluded Lt: hypoplastic	ND	LA	None	Good
Zhang et al.,2 2014	None	Extension of the Rt. ICA stenosis to the origin of the PPHA	Mo.Ma device	Bil. hypoplastic	Bil. hypoplastic	GA	None	Good
Current case	none	Lt. ICA stenosis (proximal to the origin of the PPHA)	Single-distal balloon at the ICA proximal to the origin of the PPHA, and proximal balloon protection	Rt: hypoplastic Lt: visualized	Rt: NV Lt: adult type	LA	None	Good

Bil.: bilateral; CAS: carotid artery stenting; GA: general anesthesia; GCs: guiding catheters; ICA: internal carotid artery; LA: local anesthesia; Lt.: left; ND: not described; NV: not visualized; Pcom: posterior communicating artery; PPHA: persistent primitive hypoglossal artery; Rt.: right; TIA: transient ischemic attack.

Several factors should be considered in cases of CAS for ICA stenosis and PPHA, such as the site of the stenotic lesion, prevention of embolism, and preservation of blood flow both to anterior and posterior circulation. Hence, it is necessary to change the treatment strategy in each case.

First, the site of the stenotic lesion is important because it affects distal protection. There could be three potential sites, including ICA stenosis proximal to the origin of the PPHA (Figure 5(a)), ICA stenosis associated with the origin of the PPHA (Figure 5(b)), and ICA stenosis distal to the origin of the PPHA (Figure 5(c)). When ICA stenosis is located proximal to the origin of the PPHA, the usual single-distal protection is appropriate.³ The use of both a filter and balloon device may be effective for distal protection. When the ICA stenosis is associated with the origin of the PPHA, double-distal protection for the territory of both the ICA and PPHA is often needed.^6,7 This is a high-risk procedure involving the crossing of the double-distal protection device through the severe stenotic lesion.² When ICA stenosis is located distal to the origin of the PPHA, the use of a single-distal protection device for the distal ICA may be sufficient. Similarly, in cases in which the PHA stenosis is located distal to the origin of the PPHA, the use of a single-distal protection device for the PPHA may be sufficient (Figure 5(d)).

Figure 5.

Outlining location of the PPHA and ICA stenosis. The figure below outlines the placement site of the embolic protection device.

CCA: common carotid artery; ICA: internal carotid artery; ECA: external carotid artery; PPHA: persistent primitive hypoglossal artery.

Second, the blood supply to the vertebrobasilar system is important in cases of PPHA as it affects ischemic tolerance during the procedure. The occlusion of blood flow using a balloon may lead to ischemic intolerance in the anterior and posterior circulation, and may result in a severe disability. As preoperative evaluation of the collateral flow, functional angiography is useful for the evaluation of the ischemic tolerance, such as lesion temporarily occlusion with the contralateral carotid or vertebral angiography. Double-filter protection should also be considered in some cases.⁶

In the present case, CAS was performed by using single-distal balloon and proximal balloon protection. Furthermore, flow reversal was performed when the device crossed the stenotic lesion. Proximal balloon protection is useful in cases involving crossing of vulnerable plaques or nearly occluded lesions. Proximal balloon protection is also effective for ensuring stability when the distance between the distal end of the ICA stenosis and the point of distal balloon occlusion is very short, as in the present case. Moreover, it helps ensure a safe procedure when incomplete distal protection occurs. Thus, the procedure could be completed without any complications, and this method may be acceptable treatment.

Conclusion

We describe a case of asymptomatic ICA stenosis with ipsilateral PPHA successfully treated by CAS. We review the literature and discuss appropriate treatment strategies. There are many types of ICA stenosis in cases of PPHA, and the treatment strategies are different in each case. Although procedures may be atypical and complicated, sufficient preoperative evaluation of the anatomy and cerebral circulation is required.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Conflict of interest

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