Vertebro-Basilar Artery Disease

Vertebro-Basilar Artery Disease

The two vertebral arteries and the basilar artery may be considered for con­venience as the vertebro-basilar arterial system. This system is prone to two main types ischemic disease.

Intermittent type, resulting from either vertebral artery compression in association with cervical spondylosis or from basilar migraine

Chronic type associated with generalized vertebro-basilar atherosclerosis. Both types may be associated with vertigo, deafness and tinnitus.

Intermittent Ischemia

I. Vertebral artery compression.

In cervical spondylosis intervertebral disc degeneration leads to production of osteophytes which may protrude into the intervetebral foramina and compress the vetebral arteries. Pressure by disc protrusion is also possible. If the arteries are atheromatous, the effects will be more severe. Compres­sion may occur when the head is in the normal erect position. But it is typical of this condition that compression is intermittently produced by movements of the head  especially lateral rotation or extension.. These movements may cause not only temporary impairment but even abolition of blood flow through one or both vertebral arteries, and may even impair the circulation through one internal carotid artery (Brain 1962).

Clinical features. Intermittent vertebro-basilar ischemia of this type is characteristically accompanied by vertigo induced by head  posture. Any change of posture may be critical but lateral rotation and extension of the head, i.e. looking round to one or other side or throwing the head back to look upwards, are the commonest associations. Vertigo is usually brief, Occasionally after a “jerk of the neck” the patient was immobilized with vertigo for 2 weeks. Nystagmus may be present. Caloric tests are inconstant.

Deafness and tinnitus may be present, but it is not certain whether as a result of ischemia of the end organ or brain stem.

Other symptoms associated sometimes are trigeminal dysaesthesia, diplopia or drop attacks without loss of consciousness called akinetic epilepsy.

Patients with cervical spondylosis seldom complain of regional pain but may have attacks of brachial neuralgia. Active and passive lateral flexion of the cervical spine is usually limited. Diagnosis of spondylosis is established radiographically.

Treatment. The problem is fundamentally an orthopedic one of treating so as to diminish the pressure effects upon the vessels, usually by some form of immobilization. Patients themselves learn to avoid critical head movements.

Chronic Ischaemia

2.  Vertebro-basilar atherosclerosis

Chronic brain stem ischemia resulting from generalized vertebro-basilar atherosclerosis may be associated with chronic vertigo (feelings of unsteadiness) often on getting up in the morning and high tone, bilateral, perceptive deafness. Caloric tests are inconstant. Unusual visual symptoms, attributed to poor circulation to the back of the brain like intermittent loss of vision. Positional vertigo elicited by turning the head to the sides is noted in many cases.

On positional testing, after roughly a 20 second latency, a right or left beating nystagmus, which persists as long as the head is turned to a particular side (vertebral artery test) is noted. This may be accompanied by additional symptoms such as ear fullness, or a spot in the vision, nausea and motion intolerance. Standing up, rapid head movements, walking in a dark room, not eating, exercise, and coughing or sneezing can trigger symptoms.   A CT-angiography / MRAngio helps to clinch the diagnosis.