Le vertebro-basilar arterial system convey it blood,oxygen and nutrients to the vital structures of the brain such as the brainstem, occipital lobes and cerebellum. When there is a decrease in blood flow to this trunk (ischemia), blood supply to the brain is reduced. We then speak ofvertebro-basilar insufficiency. Let's see together what there is to know about this disease.
Anatomy and definition
Le vertebro-basilar system ensures the vascularization du brainstem and cerebellum. It is made up of two vertebral arteries and the basilar trunk.
The two people vertebral arteries arise from the subclavian arteries at the base of the neck. Each of them sinks into a bony channel dug on each side of the transverse processes cervical (C1 to C6). Then, they go up to the level of the bulbo-protuberantial furrow. They then perforate the dura mater (membrane that surrounds the central nervous system) to enter the skull. They unite at the junction between the bulb and the annular protuberance to form the basilar trunk.
The vertebral arteries irrigate the upper 2/3 of the spinal cord, the lateral face of the medulla and the lower face of the cerebellum via the anterior spinal artery and the posterior and inferior cerebellar artery.
Le basilar trunk arises from the fusion of the two cerebral arteries. It ascends along the pons and divides into two posterior cerebral arteries. It gives arteries for the bulb and the pons. It is divided at the level of its termination into two pairs of vessels: on the one hand, the superior cerebellar arteries, on the other hand, the posterior cerebral arteries which irrigate the visual cortex and the internal face of the temporal lobe.
THEvertebro-basilar insufficiency describes a temporary set de symptoms due to a softening of the brain. It is caused by a decreased blood flow vertebro-basilar arterial system which irrigates the brainstem (posterior part of the brain). It is responsible for intermittent neurological accidents or permanent deficit.
With a usually hemodynamic mechanism, it is generally related to heart disease or an atheromatous lesion of the vertebral arteries or of the basilar trunk (deposition of a plaque essentially composed of lipids on the wall of the arteries).
What are the causes of vertebro-basilar insufficiency ?
The main cause of vertebro-basilar insufficiency is the alteration of the walls of the vertebral arteries and the basilar trunk. This phenomenon may be due to fatty deposits (atheroma), leading to a reduction in the caliber of these vessels.
Vertebro-basilar insufficiency can sometimes be related to other situations: a dissecting thevertebral artery or an stenosis (shrinkage) of a subclavian artery (also call subclavian steal syndrome) especially in younger subjects. In the case of dissection, neck pain often appears after hyperextension or rotation of the neck. In contrast, with subclavian steal syndrome, symptoms occur on exertion.
THEosteoarthritis of the neck can also give a picture of vertebro-basilar insufficiency. This is related to compression of the vertebral artery in the transverse canal by a huge osteophyte (bony growth around the neck joint). Symptoms occur electively with rotation of the neck which decreases the caliber of the vertebral artery on one side.
Signs and symptoms of vertebro-basilar insufficiency
The symptoms vertebro-basilar insufficiency are very varied, depending on the location (vertebral arteries or basilar trunk).
Generally transitory, a vertebro-basilar insufficiency can manifest itself by headache episodes (headaches) located at the back of the skull, occurring after an effort or a change of position.
There may also be:
- of balance disorders: like a drunken gait, clumsiness of a limb, dizziness, loss of balance…;
- of bilateral visual disturbances, type blindness (complete loss of sight), with preservation of the photomotor reflex or a perception of bright spots or bright lines…;
- of rocking motor disorders (that is to say which affects one side, then the other): for example a motor impairment of one arm, and a motor impairment of a leg in the opposite territory;
- of nausea, vomiting, the dysphagia ;
- of speech difficulties dysarthria-like (disorder of oral expression), for a few minutes, very evocative, but not quite specific;
- a lower extremity weakness ;
- of neck pain
- of paralysis ou paresthesias of one or more limbs (paresthesias can affect the face or the mouth)…
These disorders may also be accompanied by drowsiness, An confusion or an amnesia (memory disorder or loss).
Sometimes the patient may make a sudden fall « drop attack ", without losing consciousness, but has a double vision and dizziness.
Depending on the location of the obstruction, a condition of the cranial nerves is possible. The latter is manifested by a drooping eyelid and mydriasis (dilation of the pupil).
Cardiopulmonary auscultation may show vertebral systolic murmur or an subclavian systolic murmur.
How is the diagnosis made ?
Le clinical diagnosis is difficult before symptoms as varied in their appearance and intensity.
At first, a physical examination aims to identify and assess the pain perceived by the patient. The confirmation of diagnosis must be done afterwards by beams paraclinical arguments.
Cervical spine x-ray
It allows not only to determine the state of the spine, but also to look for osteophytic beaks (bone growth), which may be the cause of compression of the vertebral arteries.
Cervical and transcranial Doppler ultrasound in search of subclavian flights
It allows to appreciate the state of the vertebral arteries and the study of the carotid axes. In other words, it makes it possible to assess a carotid stenosis. Transuranic Doppler can help visualize basilar trunk stenosis and assess the quality of flow in the posterior cerebral arteries.
Computed tomography (scanner) and brain magnetic resonance imaging (MRI)
They make it possible to search for the existence of sequellar or primary ischemic intracranial lesions that can redirect the etiological diagnosis. Cerebral MRI, which is more efficient, visualizes the parenchymal consequences of micro-emboli in the form of small infarcts of the posterior fossa. These methods are therefore very interesting for distinguishing patients suffering from vertebro-basilar insufficiency of embolic rather than hemodynamic origin.
Angiography of the supraaortic trunks (failing this angiography by magnetic resonance imaging)
These methods make it possible to examine the arteries from the inside: the diameter of the vessels, the condition of their walls, and also to study in detail the channel of the vessels of the brain.
It provides images of regional cerebral blood perfusion, and thus by default, ischemic areas.
An ECG, a blood pressure holter and a cardiac ultrasound
If heart disease is suspected, these examinations may be necessary in order to identify potentially emboligenic cardiovascular dysfunctions: dysfunctions affecting the blood supply to the brain.
Otovestibular tests and audiogram eliminating purely ENT pathology.
Useful for ruling out a differential diagnosis.
Treatment of vertebro-basilar insufficiency
Le choice of methods et means of treatment depends onstate of vessels and concomitant diseases which caused the vertebro-basilar syndrome. It also depends on the severity of the disease.
Depending on the pathology diagnosed, certain medications may be prescribed to lower blood pressure. Others, to increase the diameter of blood vessels (vasodilator drugs). They are intended to prevent the formation of blood clots in vessels of low permeability.
Used during cerebrovascular accidents, this treatment consists of breaking up thrombi or blood clots, using medication.
In the presence of significant spinal stenoses, treatment is usually surgical ou endovascular (interventional). Depending on the lesion assessment, we can discuss a spinal revascularization proximal (reimplantation in the posterior cerebral artery) or distal (bypass with venous material between the primitive carotid and the vertebral in the C1-C2 space).
Sorry you couldn't find an answer to your questions!
Help us improve this article!
How can we improve the article?