07 April 2023: Articles
Case of Amaurosis Fugax in the Setting of a Persistent Primitive Hypoglossal Artery Requiring Carotid Endarterectomy with Regional Anesthesia
Management of emergency care, Congenital defects / diseasesStacey Telianidis 1ABCDEF*, Mark J. Westcott 1ABDE, Craig M. Ironfield 23BDEF, Lauren M. Sanders 45ABDEF
Am J Case Rep 2023; 24:e939450
BACKGROUND: A persistent primitive hypoglossal artery (PPHA) is a rare congenital anomaly leading to persistent carotid-basilar anastomosis. This is a report of an 83-year-old man with a PPHA presenting with amaurosis fugax of the left eye requiring carotid endarterectomy under regional anesthesia.
CASE REPORT: An 83-year-old man presented with 2 weeks of intermittent self-resolving visual disturbances, followed by an episode of left eye amaurosis fugax. The patient had been referred to the hospital for further investigation of symptoms 1 day following the amaurosis fugax event. Carotid Doppler ultrasound demonstrated a greater than 90% stenosis of the left internal carotid artery. Computed tomography carotid and Circle of Willis angiography confirmed a mixed, ulcerated plaque and revealed a persistent left hypoglossal artery originating from the left internal carotid artery and continuing as the basilar artery. On day 3 of admission, left carotid endarterectomy was performed under conscious sedation and regional anesthesia to permit continuous monitoring of neurological status and avoid the need for intraoperative shunting. “Permissive hypertension” by targeting a systolic blood pressure of 190 to 200 mmHg was sought for the duration of clamp time. There was no deterioration of neurological function during clamping of the carotid vessels. The patient recovered well and was discharged 2 days after surgery, with no residual neurology.
CONCLUSIONS: This report has presented a rare case of PPHA to highlight awareness of this congenital vascular anomaly when undertaking carotid endarterectomy.
Keywords: Carotid Artery Diseases, carotid stenosis, Central Nervous System Vascular Malformations, Endarterectomy, Carotid
Communication between the anterior and posterior circulation is a normal developmental process in embryonic neurovasculature. At 7 weeks of development, the 2 dorsal longitudinal neural arteries usually fuse to give rise to the basilar artery, while the trigeminal, otic, and hypoglossal arteries involute . A persistent primitive hypoglossal artery (PPHA) is defined by a persistent carotid-basilar anastomosis and occurs in 0.027% to 0.26% of cases . The criteria to identify a PPHA include: (1) origin from the internal carotid artery (ICA) at the level of C1 to C2; (2) enters the posterior cranial fossa; (3) via the hypoglossal canal with the accessory nerve; (4) the basilar artery will only fill distal to where the PPHA joins; and (5) the posterior communicating arteries and vertebral arteries can be hypoplastic or absent [3,4]. PPHA have been reported to be associated with intracerebral artery aneurysms  and atherosclerotic disease and cerebrovascular events .
Amaurosis fugax is a transient monocular vision loss that is most often caused by retinal ischemia or ischemia to the choroid or optic nerve . Impaired ocular perfusion can be due to vascular disease within or at a distance from the eye . Management includes ophthalmic examination to identify local causes and investigation of vasculitis and cardiac and carotid sources of emboli . In the absence of a local cause of amaurosis fugax, distant causes must be investigated, which includes assessment of carotid disease . Typically, extracranial carotid disease will present with symptoms of monocular vision impairment and/or anterior cerebral circulation hemispheric symptoms . The posterior circulation (vertebrobasilar, cerebellar, and posterior cerebral arteries) typically supplies the occipital and posterior parietal lobes, brainstem, and cerebellum . Posterior stroke therefore can present with visual field defects, oculomotor impairment, unilateral sensory or motor deficit, cranial nerve involvement, ataxia, or a combination of these signs .
Patients with variant anatomy can present with atypical symptoms involving both the anterior and posterior circulation. One study reported a case of a patient with PPHA presenting with aphasia, unilateral arm weakness, and vertigo , while another reported unilateral upper limb paresthesia and dizziness . Other cases describe a history of transient ischemic attack and aphasia, right hemineglect, and hemiparesis with right homonymous hemianopsia  as well as symptoms of dizziness and nausea . Burgard et al reviewed the management of patients with symptomatic ICA stenosis in the setting of a PPHA . The main treatment options are carotid endarterectomy (CEA) or carotid artery stenting .
It is important to consider this variable anatomy in such cases as it can influence the surgical planning and operative technique. This report is of an 83-year-old man with a PPHA who presented with amaurosis fugax requiring a CEA under regional anesthesia to avoid the need for a shunt.
An 83-year-old male presented with 2 weeks of intermittent self-resolving episodes of visual disturbance, which he described as white lines curving on the road and “furniture tilting” lasting for approximately 30 s. This was followed by an episode of left eye amaurosis fugax. He was referred to the hospital for further investigation of symptoms 1 day following the amaurosis fugax event. Comorbidities included impaired fasting glucose, hypertension, and dyslipidemia. Ophthalmologic examination revealed reduced left eye visual acuity (6/9 pin hole) and otherwise was unremarkable. Carotid Doppler ultrasound demonstrated an ICA peak systolic velocity of 480 cm/s and a peak systolic velocity ratio (ICA: common carotid artery) of 7.5. As per the North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria, this is consistent with the carotid stenosis diagnostic criteria of >90% but less than near occlusion [13,14]. Computed tomography carotid and circle of Willis angiography was undertaken to assist in surgical planning (see Figure 1). This confirmed a mixed, ulcerated plaque and revealed a persistent left hypoglossal artery originating from the left ICA 3.7 cm from its origin, ascending posterior to the ICA. This was the dominant supply to the posterior circulation with hypoplastic vertebral arteries bilaterally. The small-calibre right vertebral artery communicated with the basilar artery while the left terminated as the posterior inferior cerebellar artery. A stroke protocol magnetic resonance imaging (MRI) of the brain confirmed this aberrant anatomy with note of both old and subacute infarcts within the left frontal, parietal-occipital, and cerebellar regions.
The patient proceeded to undergo left CEA with a Braun polyurethane patch under conscious sedation (dexmedetomidine infusion 0.4 mcg/kg/h) and regional anesthesia. Ultrasound-guided regional anesthesia comprised an intermediate cervical plexus block with infiltration of the carotid sheath , and subplatysmal block . Ropivacaine, lidocaine, and adrenaline (epinephrine) were combined to create a 30-mL total volume comprising ropivcaine 0.6 mg/mL, lidocaine 13 mg/mL, and adrenaline (epinephrine) 3 mcg/mL. An intermediate cervical plexus block was performed using in-plane sonographic guidance in real-time, and a postero-lateral to antero-medial needle approach with a 100-mm 21 g SonoPlex II (Pajunk, Germany) needle. Hydro-dissection of the plane deep to the sternocleidomastoid muscle, between the investing layer of the deep cervical fascia and pre-vertebral fascia, was performed with 20 mL of the local anesthetic mixture described above, at a cranio-caudal level of C5. From the same skin puncture site, 4 mL of local anaesthetic was deposited within the carotid sheath at the antero-lateral aspect of the left common carotid artery. A subplatysmal block was performed by sono-graphically locating the space between the medial border of the sternocleidomastoid muscle and the adjacent submandibular gland immediately caudad to the mandible. A 50-mm 22 g SonoPlex II (Pajunk, Germany) needle was advanced using an out-of-plane technique deep to the platysma muscle, where 6 mL of the local anesthetic mixture was injected. The addition of the subplatysmal block anesthetizes peripheral branches of the facial nerve and superficial ansa cervicalis. The patient experienced satisfactory surgical anesthesia for the duration of the 180-min procedure, with no supplementation of local anesthetic required during surgery.
After the vessels were controlled, a metaraminol infusion (2–10 mg/h) was titrated to maintain a systolic blood pressure of 190 to 200 mmHg, with continual close neurologic monitoring by the anesthesia and neurology teams. No neurological deterioration was observed for the duration of the surgery. Operative findings revealed a near-occlusive soft hemorrhagic plaque at the origin of the left ICA (Figure 2). At the conclusion of the procedure, the systolic blood pressure was maintained within the range of 100 to 180 mmHg and remained between 110 and 140 mmHg without intervention. The regional anesthesia technique provided the patient with satisfactory postoperative analgesia. Regular paracetamol was required after the conclusion of the operation, without further systemic analgesia requirements.
Important learning points from this case include the necessity of preoperative anatomical imaging to confirm the underlying anatomy when both anterior and posterior circulation symptoms are present. The patient in the present case displayed symptoms of both the anterior and posterior circulation. The visual symptoms of “white lines curving on the road” and “furniture tilting” suggest oculomotor dysfunction and localize to the brainstem [7,8]. Preoperative computed tomography circle of Willis and MR angiography was essential here to confirm the varied anatomy and for surgical planning. This presentation of a mix of anterior and posterior circulation symptoms is similar to that of other studies [9,10].
The second learning point this case offers is the safe performance of a CEA under regional anesthesia to avoid the use of a shunt. Similar cases have been described in the literature, with patients being managed with CEA performed under general anesthesia with carotid shunting [1,10,17–19]. Of these cases, 3 reported PPAH originating from the left ICA [1,17,19], 1 case reported PPAH originating from the right ICA , and 1 case did not specify the side of origin of the PPAH . Burgard et al reviewed other cases of the management of symptomatic carotid lesion with a PPHA . Of those who underwent CEA, 66% of cases utilized an intraoperative shunt, 22% did not use a shunt, and, in 11% of cases, it was unknown whether a shunt was used or not . The postoperative outcomes of stroke , transient ischemic attack , and distal restenosis  all occurred in those patients who underwent shunting . Our case avoided such complications by utilizing regional anesthesia and conscious sedation to monitor neurologic function for the duration of the procedure. Systematic reviews outline uncertainty with respect to approaches to shunting and intraoperative monitoring when CEA is performed under general anesthesia . Previous CEA in patients with PPAH performed under general anesthesia have used multimodal neurophysiological monitoring and shunting . Although the use of a shunt is aimed to continuously supply the ipsilateral hemisphere while the endarterectomy is performed, it is not without risks. Shunt migration or distal shunt malposition can result in distal emboli and acute infarction .
Regional anesthesia for CEA avoids the need for expensive neurological monitors, as cerebral perfusion can be assessed by conversing with the patient and asking them to perform verbal and contralateral motor tasks throughout the operation. Any changes from baseline indicates early signs of cerebral hypoperfusion following clamping . The GALA study did not show a difference in postoperative stroke, myocardial infarction, or death when CEA was performed with general or regional anesthesia; however, 1-year survival data suggested fewer subsequent events in the regional anesthesia patient group . A large study using the ASC-NSQIP database revealed CEA performed under regional anesthesia is not only associated with reduced perioperative morbidity and mortality, it is also associated with shorter operative time and hospital length of stay . This result is supported by several other studies mentioned in this review .
The final learning point of the present case is that close hemo-dynamic monitoring is necessary during CEA. Autoregulation is impaired following a stroke. This is thought to be due to reduced baroreceptor sensitivity secondary to carotid atherosclerosis in addition to the effects of age, diabetes mellitus, antihypertensive medication, and effects of the carotid surgery and anesthetic . Blood pressure control in the perioperative period is important to reduce the risk of early cognitive dysfunction, which can occur as early as 24 h after CEA . It is common to target a mean arterial pressure of approximately 20% above baseline during cross-clamping of the ICA, with the aim to improve contralateral blood flow and reduce the risk of early cognitive dysfunction . One study showed that the incidence of early cognitive dysfunction is significantly lower in patients with a mean arterial pressure was ≥20% above their baseline during cross-clamp time . Transcranial Doppler monitoring of the middle cerebral artery during CEA has shown that lower mean volume flow through the middle cerebral artery is associated with an increased risk of postoperative cognitive dysfunction . In the present case, we maintained an intraoperative systolic blood pressure of 190 to 200 mmHg, and no postoperative cognitive dysfunction was observed.
This report has presented a rare case of a patient with PPHA that presented with symptoms of both anterior and posterior circulation. It is important to highlight awareness of this congenital vascular anomaly when undertaking CEA.
FiguresFigure 1.. A 3-dimentional reconstruction of the Circle of Willis anatomy illustrating the persistent primitive hypoglossal artery. A) Left persistent patent hypoglossal artery (PPHA); B) left internal carotid artery; C) lesion at the left common carotid artery bifurcation; and D) left common carotid artery. Figure 2.. Intraoperative specimen illustrating the near occlusive soft hemorrhagic plaque from the origin of the left internal carotid artery.
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