Internal carotid artery dissection associated with an elongated hyoid bone in a patient with vascular Ehlers-Danlos syndrome

Summary

Hyoid bone-related carotid injury is a rare cause of neurovascular events. This report describes a case of a young, healthy male presenting with neck pain followed by left-sided hemiparesis. The patient was diagnosed with a transient ischaemic attack attributed to structural damage of the vascular surface of the right internal carotid artery as a direct result of continuous compression by an elongated hyoid bone. We describe a successful diagnosis using a series of manoeuvres during a six-vessel cerebral angiogram. Genetic testing later confirmed the diagnosis of vascular Ehlers-Danlos syndrome.

Background

This case gives insight into manoeuvres performed throughout a six-vessel angiogram to determine the cause of a vascular injury in a young patient who presented with a new onset of neurological symptoms.

Case presentation

While at work, an individual in their 20s went to drink water after carrying a heavy load and suddenly experienced neck pain in the right side of the anterior cervical region, exacerbated by head movement. The patient later presented with decreased sensitivity in the left hemibody, dizziness and decreased visual acuity. The patient was taken to the emergency department, where neurological examination disclosed mild left-sided arm and leg weakness (4/5). The family history demonstrated that the patient’s father had passed away due to aortic dissection.

Investigations

Laboratory investigations, including serology, were within normal reference ranges. Non-contrast cranial CT showed no signs of ischaemia or haemorrhage; hence, the patient was diagnosed with transient ischaemic attack of unknown aetiology.

Doppler ultrasound of the carotid arteries (figure 1) revealed a dissection of the right common carotid artery. An enhanced angiotomography of the carotid arteries (figures2 3) revealed a dissection of the right brachiocephalic artery with extension to the right common and ipsilateral internal carotid artery (ICA).

Figure 1. Doppler ultrasound showing dissection of right the common carotid artery. (A) On transverse view (arrow). (B) Colour Doppler flow image with careful adjustment of colour gain detected the intimal flap. (C) On longitudinal view (arrow).

Figure 2. Three-dimensional reconstruction of an angiotomography analysis of the carotid arteries showing the dissection of the right internal carotid artery (red circle) (A and B).

Figure 3. A computed tomography angiography (CTA) demonstrated a close contact between the enlarged right posterior horn of the hyoid bone and the right ICA. (A and C) sagittal view. (B) Axial cut of the CT scan. (Purple arrow: posterior horn of the hyoid bone; red arrow: relationship between ICA and ECA; yellow arrow: communication between the hyoid bone and ICA). ECA, external carotid artery; ICA, internal carotid artery.

Figures4 5 show a six-vessel cerebral diagnostic digital subtraction angiography (DSA) that was performed when the patient was asked to swallow and rotate the neck to both the right and left side. The hyoid bone was observed to make an impregnation above the dissected segment of the right ICA (C1 segment) in probable relation to etiological origin. These findings concluded that mechanical compression of the ICA by the hyoid bone induced by neck rotation and extension was related to the ICA dissection.

Figure 4. Digital subtraction angiography images reveal dissection of the right ICA (encircled in yellow) and its close contact with the hyoid bone (red arrow). (A) Lateral projection. (B) Anteroposterior projection. (C and D) Oblique projection.

Figure 5. Digital subtraction angiography images in an anteroposterior projection reveal dissection involving the origin of the right brachiocephalic artery.

Findings of vessel fragility during surgery indicated a weak connective tissue disease; therefore, a genetic analysis was performed and revealed a heterozygous autosomal dominant mutation in COL3A1, c.1379_1406delinsA p.Ala460_Ser469delinsGlu, confirming the diagnosis of vascular Ehlers-Danlos syndrome (vEDS).

Differential diagnosis

A weak connective tissue disease was suspected due to the patient’s tissue fragility. To confirm the diagnosis of a connective tissue disease, genetic and molecular biological assays were performed, revealing an autosomal dominant mutation in the COL3A1 gene.

Treatment

Dual antiplatelet therapy (DAT) with aspirin and clopidogrel was initiated post-procedure; endovascular therapy was avoided due to familial history of arterial dissection and lack of evidence supporting intervention. Cervical surgical exploration confirmed the external compression of the ICA by the posterior horn of the hyoid bone, requiring bone fragment resection (figure 6). Patient was admitted to ICU post-surgery, recovering without complications.

Figure 6. Intraoperative exposure of the internal carotid artery after resection of the posterior horn of the elongated hyoid bone showing no sign of impingement.

Outcome and follow-up

Subsequent visits demonstrated full recovery of all symptoms. A 3-month follow-up visit with DSA and CTA demonstrated resolution of the right ICA; pseudoaneurysm on the right proximal brachiocephalic trunk was observed (figures7 8) but not surgically treated. Patient continues DAT daily and is currently asymptomatic.

Figure 7. Digital subtraction angiography images reveal resolution of right ICA (encircled in yellow), and an aneurysmal dilatation was observed on the right proximal brachiocephalic trunk (encircled in red). (A) Anteroposterior projection of a selective injection of right ICA showing patency of the right anterior communicating artery with retrograde filling of the left ICA and terminal branches. (B) Anteroposterior projection of a selective injection of the left ICA. (C) Anteroposterior projection of the posterior circulation. (D) Anteroposterior projection of the right CCA. (E) Anteroposterior projection reveals dissection involving the origin of the right brachiocephalic artery. CCA, common carotid artery; ICA, internal carotid artery.

Figure 8. Three-dimensional reconstruction of an angiotomography analysis of the carotid arteries showing the dissection of the right brachiocephalic trunk associated with a fusiform aneurysmal dilatation with the following dimensions: 32 × 18.8 mm (red circle) (A and B).

Discussion

Few cases have been published worldwide on neurovascular events from ICA damage by cervical bone structures. The symptoms reported in literature range from ipsilateral ischaemic cerebrovascular event to Eagle syndrome.¹,⁵ Eagle syndrome (stylocarotid artery syndrome) is a condition associated with elongation of the styloid process, which is linked with craniofacial and cervicopharyngeal pain and accompanied by dysphagia and sometimes cerebral ischemia.¹,⁵ To the best of our knowledge, this is the first report of a transient ischemic attack (TIA) in this scenario.

In this case, the patient’s symptoms could have evolved from thrombotic vessel alterations related to the proposed structural damage due to repetitive local trauma from the close contact between the hyoid bone and the ICA. During the angiography, it was noted that certain neck movements, including rotation, potentially increased regional flow turbulence, which may have induced the thrombi formation. The action of swallowing and violent coughing was also tested.

Mutations in the structural gene for human type III collagen (COL3A1), specifically deleterious genotypes like in our patient, have been associated with a reduced or defective content of the collagen produced by fibroblasts in tissue and linked as the cause of vEDS.⁶,⁸ After confirming the diagnosis of vEDS, patient did note a history of spontaneous bruising throughout life and mentioned several spontaneous deaths in young family relatives due to postpartum uterine haemorrhage and arterial rupture. On examination (figure 9), thin skin, hyperextensible joints, large eyes, thin nose and lips, a small chin and lobeless ears were observed.⁸

Figure 9. Patient clinical features: (A) lobeless ears, (B) long thin nose and lips with a triangular-shaped face and a small chin (C) hyperextension of elbows > 10°.

Patient’s perspective.

The minute I was placed on an ambulance and taken to the clinic I was very frightened. Nothing compares to the feeling of being a young and healthy man, who is trying his best to look out for his family then losing the capacity of even lifting my own arm. My doctor and his team were very honest with me once a diagnosis was achieved, it gave me an explanation as to why my father passed away at such a young age and introduced my family to a disease, none of us knew nothing about. I’m now doing the best that I can to take care of myself. Life gave me a second chance and I’m grateful to have been treated by such a wonderful team.

Learning points.

• Different manoeuvres, including neck rotation and swallowing during a six-vessel angiogram, are useful techniques in determining the relationship between vascular injury and mechanical compression as the underlying cause.

• Recognition of the possibility of a neurovascular event due to cervical structures would be helpful for proper management and prevention of future events.

• Findings of vessel fragility during surgery and in imaging studies were indicative of weak connective tissue disease. A complex case like this requires a multidisciplinary team approach, where genetic testing is also an essential part of achieving a safe treatment plan.