Vertebral Artery Dissection

Etiology

VAD can be classified as spontaneous or traumatic. Spontaneous causes of VAD are found in patients with intrinsic issues with their vasculature and can be seen in patients with connective tissue disorders and fibromuscular dysplasia. Traumatic causes can occur with minor blunt trauma to the neck. Cervical manipulation that occurs with activities such as coughing, vomiting, cervical spine manipulation, and blunt trauma are possible initiating events.[6][7][8] Blunt trauma to the neck is the most commonly reported precipitating event.

Epidemiology

The incidence of VAD is estimated to be 1 per 100,000 people. Most of the literature considers VAD as part of cervical artery dissections, which include carotid artery injuries in addition to vertebral artery injuries. Cervical artery dissection is estimated to be the cause of approximately 2% of all ischemic strokes. Data are inconclusive on any sex predilection. However, in middle-aged and younger patients (30 to 45), prevalence is believed to be as high as 10% to 25%. These numbers may be underestimated as cervical artery dissections are being identified more frequently with the increased use of imaging. This leads to widely variable estimates when reviewing the literature.

Pathophysiology

Vertebral Artery Anatomy

The vertebral artery is divided into 4 segments:

• Segment 1 extends from its origin at the subclavian artery to its entry into the cervical foramina transversarium, typically at the level of the sixth cervical vertebra (C6).
• Segment 2 continues within the foramina transversarium from C6 to the second cervical vertebra (C2).
• Segment 3 begins at the transverse foramina of C2, looping posterolaterally and then superomedially over the posterior arch of the atlas (C1) before piercing the dura.
• Segment 4 is the intracranial portion, starting at the foramen magnum and ending at the vertebrobasilar junction, where the vertebral arteries merge to form the basilar artery.

The vertebral artery consists of 3 layers: the intima (innermost), media (middle), and adventitia (outermost). Dissection occurs when the structural integrity of the arterial wall is compromised, often due to an intimal tear allowing arterial blood to enter and separate the layers. This process can lead to luminal narrowing, stenosis, or occlusion, increasing the risk of ischemia, thromboembolism, and stroke.[9] VAD is classified as extracranial or intracranial. Extracranial dissections commonly occur near the atlas (C1) and axis (C2), whereas intracranial dissections are often associated with subarachnoid hemorrhage and carry a worse prognosis. Neurological complications from both types may arise due to cerebral ischemia caused by thromboembolism, hypoperfusion, or a combination of both, with thromboembolism being the primary cause of ischemic symptoms.

History and Physical

History

VAD typically presents with acute and severe unilateral neck pain and/or headache, most commonly localized to the occipital-cervical region. This pain often follows minor neck trauma, such as chiropractic manipulation, sports injuries, or even activities involving excessive neck movement. In some cases, the dissection occurs spontaneously due to underlying connective tissue disorders (eg, Ehlers-Danlos syndrome, Marfan syndrome) or vascular risk factors like hypertension or migraine.

Neurological symptoms may be delayed or absent, but approximately 70% of patients will develop some form of neurological deficit. The lateral medulla (Wallenberg syndrome) and the cerebellum are the most common infarction locations. Symptoms of posterior circulation ischemia include dizziness, ataxia, dysphagia (cranial nerves 9 and 10 involvement), disequilibrium, unilateral hearing loss, dysarthria, diplopia, and vertigo. In severe cases, patients may present in a coma due to extensive brainstem involvement.

Extracranial dissections may be associated with a bruit, sometimes audible even on the contralateral side due to increased collateral blood flow. The presence of pain and the younger age of patients typically distinguish VAD from cerebellar infarctions due to atherosclerosis. Intracranial dissections, however, are frequently associated with subarachnoid hemorrhage (50% of cases) and have a significantly worse prognosis due to increased risk of hemorrhagic complications and severe neurological impairment.

Physical Examination Findings

Neurological examination findings depend on the extent and location of arterial compromise. Common signs include:

• Horner syndrome 
  • Ipsilateral ptosis, miosis, and anhidrosis due to sympathetic fiber involvement
• Lateral medullary syndrome (Wallenberg syndrome) 
  • Ipsilateral facial sensory loss (trigeminal nucleus involvement)
  • Contralateral loss of pain and temperature sensation in the trunk and extremities (spinothalamic tract involvement)
  • Dysphagia, hoarseness, and diminished gag reflex (nucleus ambiguus involvement)
  • Nystagmus, vertigo, and ataxia (vestibular and cerebellar dysfunction)
  • Ipsilateral loss of taste (hypogeusia) and impaired proprioception and fine touch
• Cerebellar dysfunction 
  • Truncal ataxia, dysmetria, intention tremor, and gait instability
• Internuclear ophthalmoplegia 
  • Impaired horizontal eye movements due to medial longitudinal fasciculus disruption
• Tongue deviation 
  • Deviation toward the side of the lesion if the hypoglossal nucleus is involved
• Contralateral impairment of pain and temperature sensation in the extremities 
  • Due to disruption of the spinothalamic tract

A high index of suspicion is required for VAD, particularly in young patients with new-onset posterior headaches, neck pain, and focal neurological deficits. Prompt recognition and imaging are crucial to initiating appropriate management and preventing further ischemic complications.

Evaluation

Laboratory Tests

A baseline laboratory workup should include:

• Complete blood count
  • Assess for anemia, thrombocytopenia, or infection
• Basic metabolic panel
  • Evaluate electrolyte and renal function status
• Coagulation studies
  • Screen for bleeding or clotting disorders
• D-dimer
  • Can indicate an active thrombotic process
• Inflammatory markers 
  • Useful in assessing for vasculitis
• Genetic and rheumatologic testing
  • Considered for patients with recurrent dissections or suspected connective tissue disorders (eg, Ehlers-Danlos syndrome, Marfan syndrome, fibromuscular dysplasia)

Radiographic and Imaging Studies

• Computed tomography (CT) and CT angiography (CTA)
  • Due to its rapid availability, CT is often the first imaging study obtained. This study can reveal posterior fossa infarctions, subarachnoid hemorrhage, vascular occlusions, or mural thrombus.
  • CTA is superior to noncontrast CT and is preferred in patients with risk factors, as it can identify vascular irregularities, luminal stenosis, and arterial wall thickening.
  • Vascular duplex ultrasonography may demonstrate abnormal blood flow in 95% of cases but is only specific for VAD in 20%.[10]
• Magnetic resonance imaging (MRI) and magnetic resonance angiography
  • MRI with diffusion-weighted imaging detects ischemic strokes.
  • Fat-suppressed T1-weighted MRI is particularly useful in identifying intramural hematomas.
  • T2-weighted sequences may reveal flow void irregularities, indicative of vascular stenosis or occlusion.
• Digital subtraction angiography 
  • This is considered the gold standard for diagnosing VAD, offering superior resolution for evaluating vascular integrity.
  • This is typically reserved for interventional planning or when noninvasive imaging is inconclusive.
• Transcranial doppler ultrasound
  • This can detect real-time flow disturbances in the vertebrobasilar circulation but lacks sensitivity for direct VAD diagnosis.
• Lumbar puncture 
  • Indicated if subarachnoid hemorrhage is suspected but not confirmed on initial imaging
• Cardiac studies (electrocardiogram and echocardiography)
  • These may be performed to rule out embolic sources (eg, atrial fibrillation, patent foramen ovale).

Treatment / Management

The prognosis for VAD is generally favorable for those who survive the initial dissection, with approximately 10% of patients succumbing early. A clinical follow-up study reported that 80% of patients achieve full recovery, with death typically resulting from extensive intracranial dissection, brainstem infarction, or subarachnoid hemorrhage. Most dissections heal over time without neurological deficits, though intracranial involvement significantly increases the risk of subarachnoid hemorrhage, making anticoagulation contraindicated in these cases.[11][12][13]

The primary goal of management is stroke prevention, typically achieved with anticoagulation therapy, most commonly heparin. If no contraindications exist and symptoms begin within 4.5 hours, thrombolytic therapy may be administered. Blood pressure management is crucial—hypotension can compromise cerebral perfusion and precipitate ischemic stroke, whereas hypertension can exacerbate arterial dissection progression.

All patients with VAD require hospital admission for close neurological monitoring. Endovascular therapy has emerged as a potential treatment option, though its role remains controversial, as most patients recover with anticoagulation alone. Endovascular intervention is typically reserved for patients ineligible for thrombolytics or those with subarachnoid hemorrhage. Surgical intervention, such as bypass grafting, is rarely performed due to its limited success rates.

Secondary prevention strategies focus on modifying vascular risk factors. Aspirin is recommended for most etiologies, while anticoagulation is preferred for atrial fibrillation. Most individuals with stroke, including young adults, should be started on statin therapy for long-term vascular protection.[14]

Differential Diagnosis

The following should be included in a list of differential diagnoses for VAD: 

• Cervical spine fracture evaluation
• Cervical strain
• Dissecting aneurysm
• Migraine headache
• Stroke, hemorrhagic
• Stroke, ischemic
• Tension headache
• Vasculitis affecting the vertebrobasilar circulation
• Vertebrobasilar atherothrombotic disease

Prognosis

For patients who survive the initial acute extracranial dissection, the prognosis is good with complete recovery in nearly 80% to 90% of patients. However, at least 10% will develop recurrent attacks, a major stroke, or death. Patients who have severe neurological deficits at the time of presentation usually do have a poor prognosis. Follow-up angiographic studies have revealed healing in about 60% of patients. The recovery can be prolonged and full recovery is often not possible.[3][15]

Patients who develop an intracranial dissection have a poor prognosis. Those who present with altered consciousness and neurological deficits do poorly. Intracranial vertebral dissections are often associated with brainstem infarctions, subarachnoid hemorrhage, and death. Prognosis may be very different for young patients without comorbidities like hypertension, diabetes, and smoking compared to those who have them.

Complications

Complications associated with VAD may include the following: 

• Cerebellar and brain stem infarction
• Subarachnoid hemorrhage
• Vertebral artery pseudoaneurysm