Persistent hypoglossal artery and persistent trigeminal artery presenting with posterior fossa transient ischemic attacks. Report of two cases

Symptomatic internal carotid artery stenosis in the presence of a persistent primary hypoglossal artery

OBJECTIVES

Anatomic variations of the extracranial carotid artery are rare. Persistent primitive hypoglossal artery appears with a reported incidence between 0.03% and 0.2%. We report a case of recurrent transient ischemic attacks originating from proximal internal carotid artery stenosis associated with ipsilateral persistent primitive hypoglossal artery and give a review of the existing literature.

METHODS

A 78-year-old patient with a medical history of two previous transient ischemic attacks consulted our emergency department with an acute left hemispheric stroke. Intravenous thrombolysis permitted complete resolution of symptoms. Concurrent Computed Tomography (CT) and Magnetic Resonance (MR) angiography revealed an unstable plaque causing 50% stenosis of the left internal carotid artery with a persistent primitive hypoglossal artery dominantly perfusing the posterior circulation, and bilateral hypoplastic vertebral arteries.

RESULTS

Uneventful carotid artery stenting using a proximal protection device was performed, and the patient was discharged after 12 days. Six months follow-up was uneventful with a patent stent in the internal carotid artery.

CONCLUSIONS

Treatment of symptomatic carotid artery stenosis in the presence of persistent primitive hypoglossal artery is challenging. Management should be driven by patients' co-morbidities, the anatomical localization of the lesions and local expertise. In the case of a high origin of the persistent primary hypoglossal artery, carotid artery stenting with the use of a proximal cerebral protection device is probably the preferred and simplest approach.

Endarterectomy of carotid artery bifurcation in the setting of a persistent hypoglossal artery and anomalous collateral vascular supply

Presented is a patient with carotid artery stenosis resulting in crescendo anterior and posterior circulation transient ischemic attacks. Treatment was complicated by a rare persistent hypoglossal artery (HGA) arising from the left internal carotid artery in addition to severe contralateral carotid disease, hypoplastic vertebral arteries, and incomplete circle of Willis. A carotid endarterectomy with shunting was performed, maintaining perfusion of both the proper left internal carotid artery and HGA. This is a rare case of carotid stenosis in the setting of a persistent HGA with contralateral carotid disease and highlights the importance of planning intracranial perfusion before carotid surgery.

Transient Ischemic Attack in the Setting of Carotid Atheromatous Disease with a Persistent Primitive Hypoglossal Artery Successfully Treated with Stenting: A Case Report

Fetal brain perfusion is supplied by the primitive dorsal aorta anteriorly, longitudinal neural arteries posteriorly, and anastomotic transverse segmentals. Most notable of these connections are the primitive trigeminal, otic, hypoglossal, and proatlantal arteries. With cranial-cervical circulatory maturation and development of the posterior communicating segments and vertebro-basilar system, these primitive segmental anastomoses normally regress. Anomalous neurovascular development can result in persistence of these anastomoses. Due to its territory of perfusion, the persistent primitive hypoglossal artery (PPHA) is associated with vertebral artery and posterior communicating artery hypoplasia or aplasia. As a consequence, primary blood supply to the hindbrain comes chiefly from this single artery. Although usually clinically silent, PPHA is susceptible to common cerebrovascular disorders including athero-ischemic disease and saccular aneurysmal dilation to name a few. We present a case of transient ischemic attack in a patient with a PPHA and proximal atherosclerotic disease treated by endovascular stenting. 

Persistent trigeminal artery and associated vascular variations

Persistent trigeminal artery (PTA) is the most frequent type of persistent primitive carotid-basilar artery anastomoses. Persistent trigeminal artery is usually associated with small or absent posterior communicating artery (Pcom). It may also be associated with hypoplastic vertebral and basilar arteries. Patients may present with symptoms related to hypo-perfusion of posterior circulation or microembolization from carotid artery to posterior circulation. We are presenting a 60-year-old who had recurrent episodes of vertigo and parasthesia, in whom MR angiography revealed a medial, Saltzman type 1 PTA on the left with absent ipsilateral Pcom, duplicated ipsilateral superior cerebellar artery, hypoplastic A1 segment of contralateral anterior cerebral artery (ACA), azygous ACA and hypoplastic ipsilateral vertebral artery.

Persistent primitive hypoglossal artery with retrograde flow from the vertebrobasilar system: a case report

The persistent primitive hypoglossal artery (PPHA) is one of the pairs of arterial connections that exist in the human embryo between the developing anterior and posterior circulation. Normally the PPHA arises from the cervical internal carotid artery (ICA) and passes through the hypoglossal canal to join the caudal basilar artery (BA). In most cases the vertebral arteries (VA) are either hypoplastic or aplastic and the posterior communicating arteries (PComA) are absent; thus, the main supply to the posterior circulation comes from the internal carotid via the PPHA in an antegrade fashion. Atherosclerotic plaques in the ICA and PPHA present with ischemic symptoms of both the carotid and vertebrobasilar systems. We report a case of a 53-year-old female who presented with a transient episode of left lower extremity numbness and weakness. Work-up with computed tomography (CT) and magnetic resonance imaging (MRI) showed a small watershed infarct in the right middle cerebral artery (MCA)/posterior cerebral artery (PCA) territory. Diagnostic angiography revealed severe proximal stenosis of the cervical ICA and presence of a PPHA just above the stenosis with retrograde filling from the vertebrobasilar junction to the distal cervical ICA. The patient underwent a carotid endarterectomy with intraoperative EEG monitoring. Intraoperative blood flow measurements were made before and after endarterectomy showing evidence of reversal of blood flow to a normal antegrade fashion. The postoperative angiogram showed resolution of the right ICA stenosis and persistence of the PHA. To our knowledge this is the first case report of a PPHA exhibiting reversal of blood flow from the posterior into the anterior circulation. Awareness of this embryological anomaly and its interaction with acquired atherosclerotic disease will minimize misinterpretation of vascular diagnostic studies.

Bilateral occipital infarcts associated with carotid atherosclerosis and a persistent hypoglossal artery

The persistent hypoglossal artery (PHA) is the second most common persistent embryological carotid-basilar connection and usually represents an incidental finding in cerebral arteriograms. The hypoglossal artery connects the primordial carotid artery with the longitudinal neural arteries, which later form the basilar artery. The PHA leaves the internal carotid artery as an extracranial branch, enters the skull through the anterior condyloid foramen, the hypoglossal canal and joins the caudal portion of the basilar artery. We report magnetic resonance and digital subtraction angiography findings in the first case of bilateral occipital infarctions associated with PHA and carotid atherosclerosis. The probable mechanism underlying bilateral occipital infarcts was embolism from the carotid territory to the posterior cerebral arteries. PHA may present a challenge in diagnosis and management of patients with carotid atherosclerosis and vertebrobasilar ischemia.

Lower brainstem dysfunction in an infant with persistent primitive trigeminal artery

A 6-month-old boy with persistent primitive trigeminal artery (PPTA) presented with stridor, dysphagia, delayed motor development and postural neck and shoulder dystonia. Magnetic resonance imaging/angiography and ultrasonography revealed PPTA, with flow from the dilated basilar artery to the right internal carotid artery, lower brainstem compression by the dilated basilar artery, and cerebellar vermis hypoplasia. Evoked potentials showed lower pons and medulla oblongata functional disruption. These lesions may be related to vascular etiology in the lower brainstem or to congenital malformation syndrome involving infratentorial structures. The relationship of this condition to Möbius syndrome is discussed.

Persistent trigeminal artery: an anatomic study

INTRODUCTION

The most frequent embryonic communication between the vertebrobasilar and carotid systems is a persistent trigeminal artery (PTA). It has been observed in 0.1 to 0.2% of cerebral angiograms. We found this variation in an anatomic specimen, and after microscopic dissection, we performed an analysis of the course of the PTA and its relationship with the abducens nerve and the meningohypophyseal trunk.

METHOD

A PTA was incidentally encountered in an injected cadaver specimen during a transpetrosal approach. This embryonic variation and its anatomic relationship are discussed.

RESULTS

The PTA can take either a lateral or medial course regarding its relationship with the abducens nerve. When the PTA originates from the posterolateral aspect of the posterior bend of the cavernous carotid artery (C4 segment), it crosses underneath and distorts the abducens nerve, continuing between the abducens and trigeminal nerves. When taking a medial course, the PTA arises from the posteromedial aspect of the posterior bend of the cavernous carotid at the same segment and pierces the clival dura at the dorsum sellae. Cranial nerve displacement or distortion is less likely in this variation. In an analysis of carefully described anatomic studies, the PTA and meningohypophyseal trunk were found arising from either common or separated origins.

CONCLUSION

The most frequent embryological anastomosis between the carotid and vertebrobasilar system is the PTA. Its course and relationship with the cranial nerves may determine its clinical presentation.

Carotid endarterectomy in the presence of a persistent hypoglossal artery: case report

OBJECTIVE AND IMPORTANCE

A persistent hypoglossal artery, one of the embryonic carotid-basilar anastomoses that can fail to regress in the embryo and can be observed past birth, is one of the only congenital anatomic variations of the internal carotid artery (ICA) that can complicate the performance of carotid endarterectomy. When associated with atherosclerotic carotid artery disease, the recognition and intraoperative management of a persistent hypoglossal artery is important.

CLINICAL PRESENTATION

A 72-year-old man presented with a symptom of transient right hemisphere ischemia, and although ultrasonography indicated a right ICA stenosis (and no other abnormality), angiography also demonstrated that the atherosclerotic plaque extended into the origin of a large right persistent hypoglossal artery arising 1.5 cm from the origin of the ICA. In this patient, the persistent hypoglossal artery was the only arterial supply to the basilar artery.

INTERVENTION

The patient underwent a right ICA endarterectomy, and intraoperative angiography was necessary to ensure that the persistent hypoglossal artery was the vessel shunted during the arterial repair.

CONCLUSION

Recognition of the primitive carotid-basilar anastomoses is important to surgeons who perform carotid endarterectomy and is not possible with ultrasonography alone. Intraoperative angiography enables the surgeon to accurately catheterize a persistent hypoglossal artery with a carotid shunt.

The persistent primitive hypoglossal artery: a rare anatomic variation with frequent clinical implications

The case of a persistent primitive hypoglossal artery (PHA) in a 72-year-old man dead from myocardial infarction is presented. The autopsy showed the presence of a semicircular marginal infarct on the surface of the left cerebral hemisphere. The PHA anastomized the basilar artery origin with the left internal carotid artery, running through the left hypoglossal canal together with the hypoglossal nerve. The vertebral and posterior communicating arteries were hypoplastic. The PHA represented the morphological base on which the cerebral vascular insufficiency acted, following the generalized circulatory insufficiency due to the myocardial infarct, causing the cerebral infarct. Based on the embryology of the cranial arteries and on the morphological findings we suggest that the persistence of the hypoglossal artery: 1) precedes the vertebral and posterior communicating arteries hypoplasia causing it by competition for the territory of distribution; 2) gives rise to an almost complete dependence of the cerebral circulation from the carotid system with predictable ischemic consequences in the case of a critical reduction of the carotid blood flow; 3) may be associated with an anomalous structure of the vessel wall and exposes the basilar trunk to an unusual haemodynamic stress, predisposing to the onset of aneurysms.

Primitive persistent carotid-basilar and carotid-vertebral anastomoses: a report of seven cases and a review of the literature

The persistence of embryonic carotid-basilar and carotid-vertebral anastomoses was investigated retrospectively in 4,400 cerebral angiograms. Six primitive persistent carotid-basilar anastomoses and one primitive persistent carotid-vertebral anastomosis were found. In 4,400 cerebral angiograms, the incidence of primitive carotid-basilar and carotid-vertebral anastomoses was 0.14% and 0.023% respectively. Primitive persistent anastomoses are associated with intracranial vascular anomalies, especially aneurysms. The clinical and pathological findings in combination with these primitive persistent anastomoses were also examined.

Bilateral occipital infarctions associated with carotid stenosis in a patient with persistent trigeminal artery. The Collaborators of the North American Carotid Endarterectomy Trial (NASCET)

BACKGROUND

Embolization via a persistent trigeminal artery, one of the embryonic vascular connections that may persist between the carotid and basilar arteries, is an unusual occurrence.

CASE DESCRIPTION

We describe a 76-year-old man with bilateral occipital infarctions presumably related to an ulcerated left carotid stenosis. Clinically, a left inferior homonymous quadrantanopia was present.

CONCLUSIONS

Anomalous connections between the carotid and the usual posterior circulation territory should be considered in evaluating patients with vertebrobasilar stroke. When they are identified, patients with symptoms attributable to the pontine vertebrobasilar territory supplied by the anomaly may be considered for carotid endarterectomy in the presence of concomitant severe carotid stenosis detected angiographically. Proper identification and treatment of such cases would be expected to prevent recurrence of disabling strokes in the vertebrobasilar circulation. These anomalies will likely be overlooked by ultrasound techniques and depend on good intracranial arteriographic images.

Bilateral persistent trigeminal arteries presenting with brain-stem infarction

A 43-year-old male with a left hemiparesis due to brain-stem infarction associated with bilateral persistent trigeminal arteries is reported. The clinicopathological and radiographic significance of persistent carotid-basilar arterial anastomoses in vertebrobasilar territory ischaemic attacks is also discussed.

Persistant carotido-hypoglossal artery associated with atherosclerotic stenosis treated by venous bypass

A 66 year-old woman presented with a tight but asymptomatic atheromatous stenosis in a persistant carotido-hypoglossal artery. Stenosis was documented by ultrasound Doppler tomography whereas the embryologic anomaly was disclosed by digital angiography. A successful venous bypass was done. Based on this case report, the diagnostic and therapeutic problems raised by such anomalies are discussed.

Transient bilateral occipital lobe ischemia: microembolization through a trigeminal artery

Microembolization from an ulcerated carotid artery to both occipital lobes via a persistent trigeminal artery was observed in a patient presenting with episodic bilateral central scotomata. Symptomatic relief was obtained following carotid endarterectomy. This unique pathway which resulted in occipital lobe ischemia has not been previously reported.