Pathologic Tortuosity of Carotid Arteries: Etiology, Pathogenesis, Classification, Diagnosis, Treatment

Pathologic tortuosity of the carotid arteries is a change in the normal straight course of the vessel, manifested as bends (kinking), loop-like curls (coiling), or spiral tortuosity. It can be observed in both the internal carotid artery (ICA) and common carotid artery (CCA), more often in the extracranial segment of the ICA.

• Occurs between 10% and 40% in different populations according to ultrasound studies and angiography.
• It is more common in women, especially older women.
• The likelihood increases with age due to decreased vascular elasticity and lengthening of the arteries.
• The changes are more often unilateral, but can be bilateral.

Etiology

The etiology of pathologic tortuosity of the carotid arteries is multifactorial and includes:

Congenital causes:

• Insufficiency of connective tissue structures of the vascular wall;
• Syndromes: Marfan (mutation in the fibrillin-1 gene), Ehlers-Danlos (especially its vascular form, accompanied by defects in type III collagen), Loeys-Dietz (associated with mutations in the TGF-β signaling pathway genes);
• Congenital arterial elongation with normal neck size;
• In some cases, carotid artery tortuosity occurs in several family members, indicating the possibility of autosomal dominant or polygenic inheritance.

Acquired factors:

• Arterial hypertension – leads to increased stress on the vascular wall and its elongation;
• Atherosclerosis – causes remodeling of the vessel;
• Age-related changes – decreased elasticity, fibrosis and elongation of the arteries;
• Obesity, especially in women – displacement of anatomical structures is possible;
• Iatrogenic factors – after neck surgery or vascular prosthetics.

Pathogenesis

As we age and/or certain diseases (hypertension, atherosclerosis, diabetes) occur in the artery wall:

• Degeneration of elastic fibers in the middle layer;
• Fragmentation and remodeling of collagen structures in the outer sheath;
• Increased stiffness of the arterial wall;
• Weakening of the fixation of the vessel in the surrounding tissues.

As a result, the artery becomes less resistant to bending and deformation, and at higher pressures, it lengthens and loses straightness.

It should be noted that some authors question the relationship of arterial hypertension or other cardiovascular risk factors in the genesis of carotid tortuosity in their findings.

Pathologic tortuosity (acquired and congenital) leads to altered hemodynamics in the arterial bed:

• Lengthening of the artery → formation of an S- or U-shaped course, loop formation;
• Disruption of laminar blood flow → turbulence, decreased perfusion pressure, decreased oxygen delivery efficiency;
• With certain head positions – dynamic impairment of blood flow;
• When combined with atherosclerotic plaque, an increased risk of transient cerebral ischemia.

Classification

• By localization: internal carotid artery (ICA), common carotid artery (CCA).
• By origin: congenital, acquired.

Classification by morphology:

3D models of pathologic tortuosity of carotid arteries:

S-shaped kinking of the internal carotid artery

C-shaped kinking of the common carotid artery

Coyling of the internal carotid artery

Clinical manifestations

Most cases are asymptomatic and are detected incidentally. However, in a subset of patients, tortuosity may be clinically significant:

• Dizziness, pre-syncope (often with a sharp turn of the head);
• Transient ischemic attacks;
• Tinnitus, unsteady gait;
• Decreased attention span, memory impairment;
• A throbbing mass on his neck;
• Dysphagia, hoarseness.

Diagnosis

1. Duplex ultrasound (the basis of screening):

• Estimation of vessel stroke, flow velocity;
• Possible features: curvature, turbulence,aliasingzoning;
• The criteria for stenosis are not always applicable (unlike atherosclerosis).

2. CT angiography:

• Visualization of the course of the artery;
• Clarification of the degree of deformation and its relation to surrounding structures;
• Mandatory when planning surgery.

3. MR angiography:

• An alternative to CTA for contraindications to contrast;
• Informative but less sensitive to small areas with turbulence.

4. Cerebral perfusion scintigraphy or CREST:

• When functional significance is in doubt (rarely used).

Treatment of pathologic tortuosity of carotid arteries

Conservative treatment

Modification of risk factors:

• Blood pressure control;
• Weight loss;
• Correction of lipid profile and reduction of inflammatory background;
• Smoking cessation.

Drug therapy (does not affect the presence of tortuosity, but helps in the prevention of complications)

• Disaggregants;
• Hypotensive drugs;
• In violation of lipid profile, the presence of atherosclerosis – statins;
• In asymptomatic patients, treatment with medications is prophylactic in nature.

Surgical treatment

Indications:

• Symptomatic tortuosity with confirmed impaired cerebral blood flow;
• Episodes of transient ischemia dependent on head position;
• Combination of tortuosity with hemodynamically significant stenosis;
• Lack of effect of drug therapy in functionally significant kinking.

Contraindications:

• An asymptomatic course;
• Severe comorbidities;
• Prominent calcinosis and high risks.

Standard cervical access to the extracranial segment of the internal or common carotid artery (longitudinal incision along the anterior edge of the sternoclavicular-papillary muscle) is most often used.

In the case of a high-lying bifurcation, an extended access with mobilization or partial transection of the upper edge of the sternoclavicular-papillary muscle may be necessary.

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Main methods of surgical correction

1. Resection (removal) of the twisted segment and suture with end-to-end anastomosis

• Requires sufficient vessel length without tensioning the anastomosis.

2. Carotid endarterectomy with arterial straightening

• It is used when tortuosity is combined with atherosclerosis;
• It can be classical or eversion;
• After the plaque is removed, the artery is reimplanted in a straighter position.

3. transposition of the internal carotid artery.

• Removal of the tortuous orifice of the VCA and reimplantation into a more proximal segment of the OSA;
• It is used when high tortuosity or resection with direct anastomosis is not possible.

4. Prosthetic artery

• It is performed when the ends cannot be joined after resection;
• Synthetic prostheses or autovenous grafts are used;
• The method is redundant, rarely used, more often in repeated interventions.

Intraoperative monitoring

• Intraoperative Doppler imaging – assessment of blood flow velocity before and after reconstruction.
• Bypass surgery is a temporary bypass for reconstruction on the carotid artery if there is a high risk of cerebral ischemia.
• Neuromonitoring – if possible, especially when operating on a single functioning VCA.