Vertebral Artery Dissection - Classification, Causes, Diagnosis, and Treatment

Introduction

VAD, or vertebral artery dissection, was initially described by a Canadian neurologist in the year 1970, C. Miller Fisher, and it refers to a tear resembling a flap within the interior lining of the vertebral artery in the neck and functions to supply pure blood to the skull and brain. After the flap-like tear, blood is able to enter the arterial walls and form a blood clot that thickens the artery wall, along with impeding blood flow. The patient presents with headache and neck pain as well as intermittent or permanent signs of stroke, which include- slurred speech, impaired coordination, and loss of vision. The diagnosis of vertebral artery dissection involves the use of a contrast-enhanced scan, like computerized tomography (CT) or magnetic resonance imaging (MRI). Vertebral artery dissection may take place after any kind of trauma to the neck or sudden movements. The treatment includes anticoagulation therapy. Vertebral artery dissection is not as common as carotid artery dissection, but both conditions account for a huge percentage of brain hemorrhage and paralysis in the younger age groups and middle-aged groups.

How to Classify Vertebral Artery Dissection?

There are two kinds of dissection of the arteries of the neck, and vertebral artery dissection is one of them. Carotid artery dissection is the other kind that involves the splitting of the inner layers of the carotid artery. Vertebral artery dissection is further divided into being traumatic- caused by mechanical trauma to the spine and neck, or spontaneous in action. Vertebral artery dissection is further divided into two kinds, depending on the artery that is involved, namely- extracranial or outside the skull and intracranial or inside the skull.

What Changes Occur in the Body During a Vertebral Artery Dissection?

The origin of the vertebral arteries is from the subclavian artery, and they pass through transverse foramen of the first six vertebrae in the neck. After leaving the first cervical vertebra, it catches a course that changes from vertical level to horizontal level and finally enters via the foramen magnum. Vertebral artery dissection takes place when the blood accumulates within the walls of the vertebral artery. This takes place because of a slit in the inner layer of the blood vessel that leads to blood entering the blood vessel. Once dissection takes place, two changes contribute to the episodes of stroke symptoms. In the beginning, the flow of blood through the blood vessels is disrupted because of the accumulation of blood below the vessel’s wall, resulting in insufficient blood supply or ischemia. next, irregularities are observed within the vessel’s wall, and there is an increased risk of the formation of clots because of turbulence. Thrombosis is referred to the formation of a clot. Along with this, migration of this formed clots-embolism takes place in the brain. Since the arterial wall in a different location is thin and has no structural support, subarachnoid hemorrhage occurs simultaneously or eventually.

What Are the Causes of Vertebral Artery Dissection?

The etiological factors that `lead to a vertebral artery dissection can be divided into two major categories, namely, spontaneous vertebral artery dissection and traumatic vertebral artery dissection. Vertebral artery dissection can occur just after physical trauma to the neck, a blunt injury, a traffic accident, or even just after sudden neck movements such as vigorous coughing. Connective tissue disorder may additionally be a causative agent that leads to spontaneous vertebral artery dissection The reasons for vertebral artery dissection can be categorized into two primary groups: spontaneous and traumatic. Mentioned below are a few of the causes of vertebral artery dissection.

• Ehlers-Danlos syndrome type 4.

• Marfan syndrome (a genetic condition affecting the body's connective tissues).

• Mutation of COL3A gene.

• Defective production of collagen type III and alpha one protein.

• Mutations of FBN1 gene.

• Malprodcution of fibrillin-1.

• Aneurysm of the aortic root.

• Osteogenesis imperfecta type 1.

• Autosomal dominant polycystic kidney disease.

• Pseudoxanthoma elasticum.

• Alpha 1 antitrypsin deficiency.

• Hereditary hemochromatosis.

• Fibromuscular dysplasia.

• Elevate homocysteine levels.

• MTHFR gene mutation.

• Aneurysm of the aortic root.

• Migraine.

• Whiplash injury (a neck injury resulting from a sudden and forceful back-and-forth movement of the head ).

• Severe respiratory tract infection.

• Chiropractic neck manipulation.

What Are the Signs and Symptoms of Vertebral Artery Dissection?

The main clinical manifestation of vertebral artery dissection involves a headache of severe nature and neck pain along with slurred speech and indications of a stroke. Mentioned below are a few of the signs and symptoms of vertebral artery dissection.

• Headache in the middle of the head.

• Dysfunctioning of a part of the brain.

• Transient ischemic attack.

• Posterior circulation infarct.

• Lateral medullary syndrome.

• Dysfunction of the brainstem.

• Unsteadiness.

• Lack of coordination.

• Visual loss of visual field.

• Horner’s syndrome.

• Drooping eyelid.

• Contracted pupil.

• Sunken eye.

• Subarachnoid hemorrhage.

• Accumulation of blood in the subarachnoid space.

How Is Vertebral Artery Dissection Diagnosed?

Various diagnostic methods are available to detect vertebral artery dissection and to know the presence of blood flow. The gold standard diagnostic measure for vertebral artery dissection is cerebral angiography with digital subtraction angiography. Mentioned below are a few of the diagnostic measures of vertebral artery dissection.

• Computed tomography or CT angiography.

• Magnetic resonance imaging or MR angiography with fat suppression.

• Doppler ultrasound.

How to Treat Vertebral Artery Dissection?

The aim of the treatment of vertebral artery dissection is to reduce the risk of episodes of stroke as well as damage from a distended artery. Mentioned below are the treatment modalities for vertebral artery dissection.

• Anticoagulation therapy with Heparin and Warfarin.

• Antiplatelet therapy with Aspirin.

• Thrombolysis medication.

• Angioplasty.

• Stent surgery.

• Endovascular therapy.

Conclusion

Vertebral artery dissection refers to the tear or split in the inner layer of the vertebral artery leading to stroke and related symptoms. Several agents may lead to this condition, which is broadly classified into spontaneous and traumatic. The diagnosis is primarily made through cerebral angiography with or without digital subtraction angiography. The treatment focuses on reducing the aftermath of a stroke, with surgery being the last option. The rate of survival with a positive outcome is more than 75 percent in both younger as well as middle-aged individuals.