Vertebrobasilar insufficiency

Vertebrobasilar insufficiency is a clinical syndrome caused by transient ischemia of the vertebrobasilar circulation, formed by the vertebral and basilar arteries, which forms the posterior circulation of the brain ¹. 

Epidemiology

Vertebrobasilar insufficiency is largely caused by atherosclerosis, and and shares many of the same risk factors as other atherosclerotic diseasediseases. 

Risk factors include:

• increasing age
• male gender
• hypertension
• smoking
• obesity ¹

Up to 25% of the elderly population will present with imbalance or falls secondary to vertebrobasilar insufficiency ².

Clinical presentation

Patients with vertebrobasilar insufficiency will present with symptoms related to ischemia of the posterior circulation. The most common symptoms include:

• vertigo
• dizziness
• syncope
• diplopia
• visual field deficits
• blindness
• ataxia
• imbalance
• dysphagia
• dysarthria
• unilateral weakness

PatientPatients most commonly present with multiple symptoms, which are often short-lived and reproducible ¹. A classic description of vertebrobasilar insufficiency is that of reproducible symptoms that occur with head rotation. 

Pathology

The vertebral arteries join to form the basilar artery which forms the posterior circulation of the brain. Vertebrobasilar insufficiency is most commonly caused by atherosclerosis and/or embolism. Other causes include arterial dissection, fibromuscular dysplasia, and coagulopathies ¹. 

Most commonly, atherosclerosis causes reduced blood flow and therefore perfusion of the posterior circulation. Symptoms may then be precipitated by a further reduction in perfusion, such as with orthostatic hypotension upon standing. 

Radiographic features

CT and MR angiography are most useful in defining the level and the degree of stenosis of arteries supplying the posterior circulation. The gold standard is intra-arterial angiography but this is not employed as first line-line as it is invasive and carries a 1-2% risk of stroke. Contrast-enhanced MR angiography (MRA) is more sensitive than CT angiography (CTA) in the detection of >50% stenosis, however, CTA is similar to MRA in the detection of >70% stenosis ⁴. 

Treatment and prognosis

Treatment largely consists of risk factor reduction and stroke prevention, such as managing blood pressure, cholesterol, smoking cessation and lifestyle modifications ¹.

Surgical/interventional procedures (arterial stenting) may be considered in addition to the above when clinically indicated, especially patients that are symptomatic and those with >50% stenosis ^5,6.

Differential diagnosis

• posterior circulation infarction
• basilar artery dissection
• subclavian steal syndrome
• benign paroxysmal positional vertigo (BPPV) ³