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Table of Contents    
LETTER TO EDITOR
Year : 2018  |  Volume : 66  |  Issue : 3  |  Page : 828-830

Inadvertent stent placement in the persistent hypoglossal artery: A case for caution


1 Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; Department of Neurology, Wayne State University, Detroit, Michigan, USA
2 Department of Neurology, Wayne State University, Detroit, Michigan, USA

Date of Web Publication15-May-2018

Correspondence Address:
Dr. Shyam S Rao
Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
USA
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.232348

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How to cite this article:
Rao SS, Shankar L, Rajamani K. Inadvertent stent placement in the persistent hypoglossal artery: A case for caution. Neurol India 2018;66:828-30

How to cite this URL:
Rao SS, Shankar L, Rajamani K. Inadvertent stent placement in the persistent hypoglossal artery: A case for caution. Neurol India [serial online] 2018 [cited 2018 Aug 17];66:828-30. Available from: http://www.neurologyindia.com/text.asp?2018/66/3/828/232348




Sir,

The persistent hypoglossal artery (PHA) is an uncommon vascular anomaly that results from persisence of fetal carotid basilar anastomosis. It has a reported prevalence of 0.02–0.10%.[1] The recognition of this anomaly, however, is very important as it can have significant clinical implications. We report a case of an ischemic stroke due to inadvertent ostial occlusion of the internal carotid artery (ICA) from stent placement in the PHA. We discuss the embryological development of the vertebrobasilar arterial system, the criteria to diagnose the presence of the PHA, and the importance of its recognition in clinical practice.

A 78-year old, right-handed man was evaluated after he developed global aphasia and right hemiparesis in the hospital. He had undergone stenting of the right ICA for asymptomatic, 50–69% stenosis the previous day. His medical history was also significant for a stent in his left ICA placed 5 weeks prior for asymptomatic, 50–69% stenosis based on an abnormal carotid duplex study.

He had been deemed as a 'high risk' candidate for carotid endarterectomy due to a history of congestive heart failure class 3, coronary artery disease, and hypertension.

His initial neurologic evaluation revealed a National Institutes of Health Stroke Scale of 16. He was globally aphasic with significantly impaired fluency and repetition. He could comprehend some simple commands. Also noted were right facial weakness, right hemiparesis, and right hemisensory loss.

A noncontrast head computed tomography obtained as a part of the stroke protocol was significant only for chronic small vessel ischemic disease. He did not receive intravenous alteplase (tissue plasminogen activator) as the onset of his symptoms was outside the therapeutic time window.

Magnetic resonance imaging (MRI) brain showed a small infarct in the left parietal lobe and multiple subacute infarcts in the anterior cerebral artery/middle cerebral artery (ACA/MCA) watershed zone in the left cerebral hemisphere [Figure 1].
Figure 1: MRI showing infarcts - Diffusion weighted imaging shows small sub acute infarcts in the anterior cerebral artery-middle cerebral artery watershed zone in the left cerebral hemisphere

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Also noted was absence of flow signal voids in the left ICA and bilateral vertebral arteries, and presence of an “aberrant” extremely prominent artery in the left hypoglossal canal consistent with the presence of a PHA. This was further evaluated with a cerebral angiogram that confirmed the presence of a PHA [Figure 2]. The left common carotid artery (CCA) bifurcates into the left external carotid artery (ECA) and a common trunk consisting of the PHA and the left ICA. The PHA then traverses the hypoglossal canal and continues as the vertebral/basilar artery that terminates with the origin of the bilateral posterior cerebral arteries.
Figure 2: Stent in the PHA on cerebral angiogram - Cerebral angiogram reveals the stent inadvertently placed in the persistent hypoglossal artery (small arrow), with the origin of the true ICA compromised by the mid-distal segment of the stent (arrowhead). The long arrow points to the basilar artery perfused by the persistent hypoglossal artery

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The previous stent was inadvertently placed in the PHA. The origin of the true left ICA at the proximal cervical segment medially was being compromised by the mid-distal aspect of the stent, resulting in severe iatrogenic stenosis at its origin. There was significant hypoperfusion of the left MCA/ICA and ACA territory evidenced by delayed transit time in comparison to the posterior circulation vessels.

Over the next week, the patient's neurologic examination improved significantly with return in fluency of speech, naming, and repetition. He continued to have mild persistent weakness in his right upper and lower extremities. Upon subsequent questioning, when his speech improved, the patient stated that he had been experiencing intermittent short-lasting episodes of right upper extremity weakness and speech difficulty for approximately 1 month, beginning soon after the left-sided stent was placed.

Stenting of the “real” left ICA was considered technically difficult and hence a left ECA/ICA bypass was performed to augment blood flow to the left ICA. The patient tolerated the procedure well. He was eventually discharged to the inpatient rehabilitation unit. On follow-up at 1 year following the event, conducted via a telephonic conversation, the patient reported no further episodes of neurologic deficits. His baseline deficits had resolved with the exception of mild persistent right leg weakness.

This case illustrates the importance of knowledge of anatomy prior to any procedure and the specific recognition of rare but important anatomical variants of intracranial arteries, such as the PHA.

The embryology of the vertebrobasilar system is intricate. Following the development of bilateral ICAs from the third branchial arch artery and the distal aspect of the dorsal aorta, the posterior circulation originates as bilateral longitudinal neural arteries in the hindbrain region of the 4 mm embryo (ovulation age 29 days). These arteries are supplied in a cranio-caudal distribution by paired carotid basilar anastomoses, namely the trigeminal artery, otic artery, hypoglossal artery, and the suboccipital inter-segmental artery.

In the 5–6 mm embryo, the posterior communicating arteries form and take over the function of the carotid basilar anastomoses, which consequently degenerate and regress. The otic artery is the first to regress, followed by the hypoglossal and trigeminal arteries. At the same time, the longitudinal neural arteries fuse to form the basilar artery. In the 7–12 mm embryo, the vertebral arteries develop from a transverse anastomosis between the suboccipital intersegmental artery and cervical intersegmental arteries, proceeding downward to the sixth cervical intersegmental artery that forms the origin of the vertebral artery from the subclavian artery. The typical lifespan of the trigeminal, hypoglossal, and otic arteries is approximately 1 week.[2],[3],[4]

The PHA is present when (a) the hypoglossal artery arises as an extracranial branch of the ICA, (b) passes through the hypoglossal canal, and (c) the basilar artery originates from the persistent primitive hypoglossal artery.[4]

Interestingly, in our patient, the left CCA gave rise to a common trunk consisting of the PHA and the left ICA.

As evidenced in our case, the presence of the PHA can result in false positive carotid duplex studies, hence confirmation of the anatomy with alternate imaging modalities such as angiography is essential prior to any planned intervention. The PHA is often the dominant vascular supply to the brainstem/cerebellum. Preoperative awareness of its presence is, therefore, crucial as brainstem ischemia could result from ICA cross-clamping during carotid endarterectomy.[5]

In patients with the persistence of carotid basilar anastomosis, carotid atherosclerotic disease could present with posterior circulation symptoms, confusing the clinical scenario.[6],[7],[8]

Surgery can be considered a viable treatment option in specific cases.

An ECA/ICA bypass was performed to prevent further ischemic strokes as stenting of the “real” ICA was technically difficult and the infarcts were thought to be a result of hypoperfusion based on their distribution in the watershed territories on MRI as well as by delayed filling of the ACA and MCA compared to the posterior circulation on cerebral angiogram. In cases where the ostium of the ECA is also occluded by the proximal end of the stent, a CCA/ICA bypass could be considered.

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.



 
  References Top

1.
Oelerich M, Schuierer G. Primitive hypoglossal artery: Demonstration with digital subtraction-, MR- and CT angiography Eur Radiol 1997;7:1492-4.  Back to cited text no. 1
    
2.
Paget DH. The development of the cranial arteries in the human embryo. Contrib Embryol 1948;32:205-62.  Back to cited text no. 2
    
3.
Luh GY, Dean BL, Tomsick TA, Wallace RC. The persistent fetal carotid-vertebrobasilar anastomoses. AJR Am J Roentgenol 1999;172:1427-32.  Back to cited text no. 3
[PUBMED]    
4.
Brismar J. Persistent hypoglossal artery, diagnostic criteria. Report of a case. Acta Radiol Diagn (Stockh) 1976;17:160-6.  Back to cited text no. 4
[PUBMED]    
5.
Widmann MD, Sumpio BE. Persistent hypoglossal artery: An anomaly leading to false-positive carotid duplex sonography. Ann Vasc Surg 1992;6:176-8.  Back to cited text no. 5
[PUBMED]    
6.
Voronovich Z, Grandhi R, Zwagerman NT, Jadhav AP, Jovin TG. Manual aspiration thrombectomy for basilar infarction in the setting of a persistent primitive hypoglossal artery: Case report and review of the literature. Surg Neurol Int 2014;5:182.  Back to cited text no. 6
[PUBMED]  [Full text]  
7.
Silva CE, Romero Adel C, Freitas PE. Persistent primitive hypoglossal artery associated with brain stem ischemia in a young patient. Arq Neuropsiquiatr 2013;71:194-5.  Back to cited text no. 7
    
8.
Kawano H, Inatomi Y, Hirano T. Cerebral infarction in both carotid and vertebrobasilar territories associated with a persistent primitive hypoglossal artery with severe dilated cardiomyopathy. J Stroke Cerebrovasc Dis 2014;23:176-8.  Back to cited text no. 8
    


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