Vertebrobasilar insufficiency

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

The concept of “vertebrobasilar insufficiency” was first described in 1961 by Niedermeyer.^[1]

There isn’t classification about the VBI yet, but there are three phenotypes of the basilar artery occlusion depending on the modal of initial symptoms.

The causes leading to VBI is primarily the vasulcar ones, like atherosclerosis and cardioembolism, etc. As the vertebral artery is in the cervical vertebra, the orthopedical lesion also contribute to part of the causes.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

In a long time in history,the VBI didn’t arouse enough focus because it is suppoesd to present only relatively benign synptoms and better outcomes. With the development of the diagnosis and perception, the VBI is believed to present a high recurrent risk and deserve a positive treatment and prevention.

The first surgical correction of vertebral artery stenosis was published by Crawford and De Bakey in 1958.^[1] Transposition of the proximal vertebral artery to the common carotid was described by Clark and Perry in 1966.^[2] The saphenous vein was used to bypass vertebral artery origin stenoses during 1970s.^[3] The approach to the distal vertebral artery was first described by Matas^[4]and was used for the treatment of traumatic injury.And in 1978,the carotid endarterectomy was proved to produced relief of symptoms in 90% of the patients.^[5] In 1981, Motarjeme et published the first case of vertebral artery origi angioplasty.^[6] In the recent 30 years, different kinds of surgery was rapidly developed to treat the VBI, such as fenestration, passby surgery. With the development of interventional techniques, more and more attemps have been made to treat the VBI, but there isn’t enough comparative evidence to support the benefit of interventional therapy.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

There isn’t classification about the VBI yet, but there are three phenotypes of the basilar artery occlusion depending on the modal of initial symptoms.

• phenotype 1: patients present progressive brain stemsymptoms(for example: vertigo, doublevision, dysarthria, hemiparesis, or paresthesia) without any prodromal symptoms.^[1]
• phenotype 2: patients present nonspecific, such as nausea, tinnitus, hearing loss, and vertigo, which can precede the onset of the monophasic, progressive deficits by days, but typically by several weeks.^[2][3]
• phenotype 3: patients present symptoms with onset of severe, often bilateral motor weakness, ophtalmoplegia, and coma. The patients may have a severe outcome if basilar artery cannot be recanalized fast.^[1]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

The vertebral and basilar arteries supply the brain stem, cerebellum, and in most cases also the inferior temporal lobe, occipital lobe, and thethalamus. Variaties of reasons lead to impress the vertebral artery directly or indirectly may reduce the blood stream of posterior circulation of the brain; stimulation caused by the pathologic changes excite the sympathetic nerve and lead to the spasm of vertebral artery finally. Normally, the reduction of blood supply of unilateral veterbrobasilar artery doesn’t arouse the ischemia of brain. However, beacuse of the pre-existing maldevelopment, stenosis, embolism or other reasons leads to the reduction of blood supply of contralateral veterbrobasilar artery, patient will suffer the symptoms of ischemia of conrresponding brain area. Sometimes, the reduction of unilateral vertebralbasilar is too serious that the compensation of blood from the unjuried side isn’t enough to maintain the normal function of brain, the patient also suffer the symptoms. The sense organs of the visual, vestibular, and proprioceptive systems are connected with the cerebellum by way of the vestibular nuclei in the brainstem. Any disease that interrupts the integration of these 3 systems may give rise to symptoms of vertigo and disequilibrium.^[1]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

The causes leading to VBI is primarily the vasulcar ones, like atherosclerosis and cardioembolism, etc. As the vertebral artery is in the cervical vertebra, the orthopedical lesion also contribute to part of the causes.

• Vertebrobasilar aneurysm
• Stroke caused by arterial embolism
• Subarachnoid hemorrhage caused by vertebral artery dissection

The most common causes of VBI are cardioembolism, atherosclerosis, and small artery disease.^[1]

arterial embolism

fibromuscular dysplasia

arteritides

Spinal disc herniation

Cervical injury

Cervical spondylosis

Cervical tuberculosis

degenerative cervical spine changes

Intracranial atherosclerosis

maldevelopment or absent of unilateral vertebral artery

Osteoporosis

Postural changes

rotational VA occlusion

subclavian steal syndrome

Takayasu’s arteritis

vertebral artery dissections

vertebrobasilar aneurysm

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

It’s often challenging to make an accurate early differentia diagnosis between the high-risk posterior circulation ischaemic events and carotid artery events before brain imaging.The Digital subtraction angiography(DSA)is the gold standard to diagosis the VBI.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [3]

The incidence of VBI increases with age and typically occurs in the seventh or eighth decade of life. Reflecting atherosclerosis, which is the most common cause of VBI, it affects men twice as often as women and is more prevalent in African Americans. Patients with hypertension, diabetes, smoking, and dyslipidemias also have a higher risk of developing VBI. And intracranial atherosclerosis is more common in individuals with black African^[1]or East Asian ethnic origin than in Caucasian populations^[2] The stroke caused by VBI account for approximately 20% to 30%21–23 of all strokes^[3] A study indicates that prevalence of >50% vertebral and basilar arterial stenosis, and vertebrobasilar arterial stenosis was more often associated with multiple ischemic episodes and a higher risk of early recurrent stroke.^[4]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [3]

The risk factors of VBI is similar to atherosclerosis. Sudden or excessive neck movement might increase the risk of vertebral artery dissection which might cause the VBI.^[1]

The atherosclerosis risk factors

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Some VBI is caused by the embolus from subclavian artery or atherosclerotic lesions and dissection, etc. Once the blocked vertebral artery doesn’t get enough compensation from the contralateral, obviously multiple and multifocal infarcts in the brain stem, cerebellum symptoms will be observed immediately,and quickly develop to a severe outcome. Some patients present nonspecific symptoms, such as nausea, tinnitus, hearing impairment, and vertigo, which can precede the onset of the monophasic, progressive deficits by days, but typically by several weeks.

The prognosis of VBI vary depending on the severity of symptoms the patients present, such as:

• Severe stroke or TIA?
• The type of stroke?Ischemic and hemorrhagic?
• The size and location of infarction or hemorrhage?
• If the patient get an early diagnosis and treatment or not?

For patients who experience vertebrobasilar transient ischemic attack portends a 30%to 35% risk for stroke during a 5-year period, whicih is higher than patients with carotid events in the acute phase, but that this is reversed in the subacute and chronic.^[1][2][3] In patients with clinically defi nite vertebrobasilar TIA, the absolute risk of stroke at 1 year was 17·1%.^[4] Medical refractory disease of the vertebrobasilar system carries a 5% to 11% risk of stroke or death at 1 year.^[5] Mortality associated with a stroke is high, ranging from 20% to 30%.^{[5] [6][7][8]} Patients presenting with VB events are more likely to have a recurrent TIA than patients with carotid events.^[5] If the basilar artery is occluated, the death or disability rate is close to 70%.^[9] Algorithms using diffusion-weighted imaging(DWI) or CT-based scoring systems have been published for prognostic assessment of early ischemic injury in basilar artery occlusion to distinguish those patients who will most likely benefit from recanalization from those who will not.^{[10][11][12][13]}

Complications of vertebrobasilar circulatory disorders are stroke and its complications. The complications of stroke include:

• Respiratory (breathing) failure (which may require use of a machine to help the patient breathe)
• Lung problems (especially lung infections)
• Heart attack
• Dehydration and swallowing problems (sometimes leading to the placement of tubes in the stomach for artificial feeding)
• Problems with movement or sensation, including paralysis and numbness
• Formation of clots in the legs

Complications caused by medications or surgery may also occur.

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