Hypoglossal nerve palsy due to cervical ICA dissection and pseudoaneurysm: A case treated with endovascular stent placement

Abstract

Internal carotid artery dissection and pseudoaneurysm is a rare vascular abnormality that can result in a wide range of morbidity and mortality. There is a variety of treatment options that are often dependent on the degree of presenting symptoms. The case presented herein is that of a 43-year-old man that is otherwise healthy presenting with cranial neuropathy related to a left internal carotid artery pseudoaneurysm. Although cases can be medically managed, in symptomatic patients, stent grafting provides the greatest risk/benefit ratio.

Introduction

Internal carotid artery (ICA) dissection and pseudoaneurysm can be a life-altering pathology, with presenting symptoms ranging from a mild headache and neck pain to nerve compression, epistaxis, stroke, and death. The incidence of spontaneous ICA dissection is estimated to be 2.5-3 per 100,000, and are an important cause of ischemic stroke in young and middle-aged adults, accounting for 10-25 percent of these cases [1].

Though often caused by trauma, spontaneous pseudoaneurysms may also occur. When nerve compression is a presenting symptom, the inferior cranial nerves are most often involved, with the hypoglossal nerve (CNXII) being the most common. The cause of cranial nerve palsy in these patients is disputed, with the leading hypothesis being compression-induced palsy. Other alternative hypotheses include infarction of the nerve or congenital malformations predisposing patients to nerve infarct.

Management of these pseudoaneurysms is via surgical or endovascular management, with a recent propensity for endovascular management due to reduced morbidity and mortality [2]. The case presented herein demonstrates a pseudoaneurysm with presenting symptoms related to CNXII compression managed with endovascular placement of a covered stent.

Case report

In this case, a 43-year-old male presented with 2 weeks of headache and fatigue, 1.5 weeks of throat fullness, and tongue deviation to the left for 1 day (Fig. 1). The patient has no past medical history or past surgical history, and denies any personal or family history of bleeding or clotting disorder. He reports a recent episode of cold like symptoms including cough and nasal congestion. He denies any family history of malignancy, heart disease, or stroke, though reports a family history of a stage IV nasopharyngeal cancer in his brother, a nonsmoker. He also denies any current medication usage. On initial physical examination, his pulse was 67 with an oxygen saturation of 100 on room air and a blood pressure of 181/105. He was afebrile with a temperature of 97.9 F. Tongue deviation to the left was noted. There were no additional neurologic findings on complete neurologic examination. All values on his basic metabolic panel, complete blood count, INR, and coagulation factors were within normal range. A COVID titer was negative, and obtained due to his recent history of cold like symptoms.

Fig. 1.

The patient demonstrates leftward tongue deviation on presentation. The patient complained of tongue deviation for 1 day prior to hospital presentation.

Given his presenting symptoms, a cranial neuropathy was suspected, though a stroke involving the posterior circulation could not be ruled out. Due to hospital resource availability, a contrast enhanced computed tomography angiography (CTA) of the head and neck was obtained. This demonstrated a linear hypodensity within the ICA compatible with dissection, with associated focal aneurysmal dilatation measuring 9 × 6 mm (Fig. 2). This finding is compatible with a wide necked pseudoaneurysm along the distal cervical portion of the left internal carotid artery, proximal to the hypoglossal canal. Additionally, there was edema within the left tongue, with tongue protrusion into the left vallecula (Fig. 3). There was no evidence of a soft tissue mass or inflammation.

Fig. 2.

CTA of the head and neck. Axial image (A) demonstrates a dissection of the distal cervical ICA with pseudoaneurysm formation (white arrows). Coronal image (B) provides another view of the dissection and pseudoaneurysm (white arrows), demonstrating the proximity to the craniocervical junction.

Fig. 3.

CTA of the head and neck demonstrates enlargement of the intrinsic and extrinsic musculature of the tongue with left-sided protrusion and muscular edema (white arrows).

The next day, magnetic resonance imaging (MRI) of the head and neck was obtained following administration of gadolinium contrast. A focal area of T1 hypointensity posterior to the ICA at the level of the carotid canal was identified, compatible with a diagnosis of a partially thrombosed pseudoaneurysm and dissection of the distal cervical portion of the internal carotid artery (Fig. 4). Similar to the previously obtained CT, there was asymmetric enlargement and mild edema of the left intrinsic and extrinsic tongue musculature with mass effect on the left vallecula.

Fig. 4.

T2 FLAIR sequence on an MRI of the head demonstrates a heterogenous focus measuring 5 × 9 mm at the level of the left distal cervical internal carotid artery, just proximal to the craniocervical junction (white arrows). This is compatible with ICA dissection and pseudoaneurysm, and directly abuts the hypoglossal canal (open arrow).

A neurology and neurointerventional radiology (NIR) consult were placed, and the decision was made to take the patient to the interventional radiology suite. Arterial access was gained via the right common femoral artery. Cerebral angiography was performed following selection of the right common carotid artery, and subsequently the left common carotid and internal carotid arteries. A Shuttle sheath was then exchanged and parked in the left internal carotid artery. A Navien .058 (Medtronic, USA) and Phenom 27 microcatheter (Medtronic, USA) and Synchro2 microwire (Stryker, USA) were threaded into the sheath and secured in the left distal M1 segment. A Pipeline 5 × 25 mm flow-diverter stent (Medtronic, USA) was threaded over the microcatheter. Using fluoroscopic and roadmapping guidance, the flow-diverting stent was unsheathed and deployed across the pseudoaneurysm at the cervicocranial junction. There was no complication during or after the procedure. The patient was discharged 2 days later without complication on dual anti platelet therapy, the typical anticoagulation regimen used for patients with similar stents.

Upon follow-up examination 6 weeks after the patient initially presented, the patient reported resolution of his tongue deviation, though reported this had improved by 2-3 weeks. He denied any neurologic symptoms or neck pain.

Discussion

ICA dissection and pseudoaneurysm is a potentially life-threatening pathology that is most common in young to middle age adults, like in this case presentation [1]. Peripheral cranial nerve palsy secondary to ICA dissection is rarely observed, but is a known symptom.

ICA dissection is often a result of spontaneous or traumatic injury. The incidence of spontaneous dissection ranges from 2.5 to 3.0 per 100,000, with the incidence of traumatic ICA dissection ranging from 1-3 per 100,000 [1]. Spontaneous dissection can be asymptomatic or present with a wide variety of symptoms, making diagnosis challenging. In approximately 33% of patients, a spontaneous dissection presents as pain on 1 side of the head, face, or neck that is followed by oculosympathetic palsy. Cerebral or retinal ischemia can be seen in the preceding hours to days [3]. As in our case, cranial nerve palsies can also be a presenting symptom in carotid artery dissection, though ipsilateral cranial nerve palsies may be under-diagnosed due to symptom masking from a contralateral stroke. Of the cranial nerves, CNXII is the most commonly affected nerve, though several cases of palsy of the ninth and 10th cranial nerves have been reported in the literature [4].

Though the etiology of spontaneous ICA dissections is unknown, anomalies of the arterial wall are suspected in the majority of cases. As a result, evaluation of any underlying etiology should be considered in these patients, evaluating for disorders such as Ehlers-Danlos, Marfan syndrome, fibromuscular dysplasia, osteogenesis imperfecta, polycystic kidney disease, infection, or vasculitis [3,[5], [6], [7]]. In rare cases, Eagle syndrome, or an elongated styloid process, has been hypothesized as the source of an ICA dissection [8]. Though the patient in our case had none of these underlying pathologies and appeared to be the result of a partially thrombosed spontaneous pseudoaneurysm, workup on an outpatient basis for an underlying pathology should be considered in every case. The patient in this case presentation did not receive further workup within our hospital and clinic network.

Diagnosis of intracranial ICA pseudoaneurysm should be considered in any patient with an isolated, ipsilateral cranial nerve disorder, such as the tongue deviation noted in our patient. Other differential diagnoses that are important to consider in the workup include stroke, infection, and traumatic injury. Diagnosis can be made with CTA or MRI/MRA, though the preferred modality is MRI. Characteristic CT imaging findings are consistent with dissection and pseudoaneurysm elsewhere in the body, and include an expansile hyperdense mass that may demonstrate erosion into adjacent bony structures. Subacute or chronic skull base fractures are commonly seen and compatible with traumatic etiology. Patterns on MRI typically include mixed T1 signal with peripheral hyperintense T1 signal consistent with partial thrombosis, as noted in our patients’ MRI. Additional findings include central T2 hypointense signal is indicative of flow-related signal loss [[9], [10], [11]]. Vessel-wall MRI is an additional imaging tool that can be used for further sensitivity in the detection of nonstenotic lesions, and has been shown to provide further characterization of stenotic ICA dissections. Conventional angiography is no longer used as a diagnostic tool, as it only provides information regarding the vessel lumen [12]. While not a diagnostic tool, conventional angiography remains the mainstay of treatment in symptomatic patients [1,13].

Considering the rarity of ICA pseudoaneurysms, there is a lack of evidence on the optimal treatment of spontaneous ICA dissection in asymptomatic patients. Management of ICA dissections can be accomplished with anticoagulation therapy, the preferred modality in asymptomatic patients, though close monitoring with imaging studies may be warranted. In symptomatic patients, stent grafting is the preferred modality of treatment, though coil embolization or angioplasty can also be used. In the case of our symptomatic patient, stent grafting was the preferred management as discussed above. Though an off-label use of the flow-diverting stent, which is commonly used in intracranial vessels, the experience of our neurointerventional radiologist has shown it to be successful in management of intracranial pseudoaneurysms, as well as pathology near the carotid canal, such as in the above described case. In the above described case, surgical management would be difficult due to proximity to the skull base and is often further complicated by extension of the dissection or pseudoaneurysm into the intracranial portions of the ICA. Surgical management can be considered in ICA pseudoaneurysms of the lower cervical ICA. With all of these treatment modalities and the wide variety of presenting symptoms, it is important to cater the treatment modality to the specific case [13]. In our case in particular, in a young healthy man without other adverse symptoms, stent grafting was considered to be the treatment method with the lowest risk for additional adverse events.

Though there are very few cases in the literature that are similar to the above described case, stenting the ICA pseudoaneurysm in symptomatic patients appears to be the preferred modality [13,14]. In our patient, the stent was the optimal decision due to the wide neck of the patient's pseudoaneurysm.

In conclusion, while spontaneous ICA dissections are a rare phenomenon, they should be considered in the setting of unilateral lower cranial nerve palsy, such as the tongue deviation in our patient. If a cervical ICA dissection is suspected, CTA and MRI evaluation are the preferred modalities, with MRI enabling the identification of wall hematomas. Endovascular treatment, ideally stent grafting, remains the mainstay of therapy in symptomatic patients.

Patient consent

Written informed consent was obtained by the authors from the patient in question for publication of this interesting case.