Vertebrobasilar insufficiency is a reversible violation of cerebral function caused by a decrease in blood circulation in the vertebral system and the main arteries. Pathology combines various neurological disorders: vestibulo-atactic syndrome, sensorimotor deficits, impaired function of the auditory and visual analyzers in combination with disorders of the cognitive-emotional sphere. Diagnosis is carried out on the basis of anamnesis and clinical examination data, confirmed by vascular and neuroimaging methods. Complex treatment consists of medication and physiotherapy, surgical correction.
G45.0 Vertebrobasilar arterial system syndrome
Vertebrobasilar insufficiency (vertebrobasilar arterial system syndrome) is widespread in the population, accounting for 38% of all neurological diseases. This condition is associated with 25-30% of ischemic strokes, 70% of transient disorders of cerebral hemodynamics. TIA with lesions of the vertebral-basilar system occur in 14 cases per 100 thousand population. Spondylogenic variants of pathology are more typical for young and middle-aged people (20-50 years), whereas chronic disorders of cerebral circulation are usually found among the elderly. Women and men suffer equally often.
The insufficiency of the vertebral-basilar system is caused by a complex of disorders that provoke a decrease in the intensity of blood flow through the vertebral and main arteries. The causes can be vascular and extravascular, nonvertebrogenic and vertebrogenic. The patency of the cervico-cerebral arteries worsens under the influence of a large number of factors:
- Atherosclerosis and thrombosis. Arterial stenoses of the vertebral-basilar basin are usually associated with atherosclerosis of the vertebral vessels. Intracranial areas are more often exposed to thrombotic occlusion. The hemodynamic significance of stenoses increases with defects of collateral supply, arterial hypotension, embologenic plaques.
- Congenital anomalies. Symptoms of VBI progress in the presence of vascular defects – hypoplasia, anomalies of the departure, location and fusion of the vertebral arteries, absence or doubling of the posterior connective branch. Pathological tortuosity and inflection of the vertebral vessels may be congenital in nature when exiting the bone canal.
- External compression. The extracranial parts of the vertebral arteries are subjected to extravasal compression with injuries of the cervical spine (spondylolisthesis, herniated discs), the presence of bone anomalies, musculotonic syndromes. Degenerative-dystrophic pathology is of great importance – osteochondrosis, spondylosis, spondyloarthrosis.
The vascular lumen narrows with arterial dissection, vasculitis (autoimmune, infectious), microangiopathies (hypertensive, diabetic). Symptoms of cerebrovascular disorders occur with fibromuscular dysplasia, spinal theft syndrome. Additional risk factors are coagulopathy, cardiac arrhythmias.
Blood flow deficiency in VBI covers areas from the cervical spinal cord to the occipitotemporal lobes of the brain, including the medulla oblongata, the cerebellum and the thalamo-hypothalamic zone. This leads to a failure of cerebral autoregulation, functional disorders. Lack of oxygen and glucose triggers the mechanisms of oxidative cell damage, glutamate excitotoxicity, metabolic and energy shifts. Neuronal apoptosis plays an essential role, especially in transient ischemic disorders.
Circulatory hypoxia appears to be a dynamic process that implies the reversibility of structural and functional changes in brain tissues. This is largely due to increased angiogenesis under the influence of synthesized growth factors, redistribution of hemodynamics in the Willisian circle, but this response is often insufficient to restore normal perfusion. Sudden intense dyscirculation provokes the development of acute ischemic damage.
Neurologists distinguish several types of VBI:
- Spicy. Transient vertebrobasilar dyscirculation accounts for the majority of all TIA. It happens rarely (1-2 times a year), of medium frequency (3-6 times), frequent (monthly or more often). Acute cerebral ischemia occurs in mild, moderate or severe forms.
- Chronic. Insufficiency of cerebral hemodynamics can be considered as a variant of dyscirculatory encephalopathy. There are compensated (initial), subcompensated (moderate), decompensated (pronounced) forms. Pathology has a paroxysmal or permanent course.
- Spondylogenic. Vertebral artery syndrome is caused by extravasal changes in the cervical spine. According to the degree of hemodynamic disorders, spondylogenic pathology passes through dystonic (functional), ischemic (organic) stages.
- Symptomatic. Cerebral insufficiency syndrome is inherent in many diseases. It is included in the picture of vegetative-vascular dystonia, arterial hyper- and hypotension, neurotic and somatoform reactions. Symptoms of ischemia occur with degenerative-dystrophic pathology of the spine, which does not have an extravasal effect.
Clinical manifestations of acute vertebrobasilar insufficiency are very polymorphic. The degree of their severity is determined by etiopathogenesis, the strength and duration of pathological effects. In the acute form, the neurological deficit is short–term and completely reversible – all symptoms disappear during the day. It is characterized by rapid development, when less than 2 minutes pass from the beginning to the most pronounced picture.
Vestibular disorders occupy a central place in the clinical picture of transient neurological disorders. Paroxysms of systemic dizziness often occur, lasting from several minutes to several hours. Other symptoms are represented by an imbalance, fine-grained nystagmus, nausea and vomiting. The picture is complemented by cerebellar syndrome, characterized by intentional tremor, adiadochokinesis.
Visual and oculomotor disorders are common – deterioration of visual acuity, photopsia, hemianopia. Transient motor deficiency (weakness, paresis or paralysis) is combined with numbness of the face and limbs. The examination may reveal elements of alternating syndromes (Weber, Millard-Gubler, Wallenberg-Zakharchenko). Sometimes cerebral lesions occur as lacunar strokes with isolated hemiparesis, hemihypesthesia, hemiataxy.
Chronic forms of vertebral-basilar insufficiency have a permanent character, are rarely affected by provoking factors, their symptoms persist between ischemic attacks. Dyscirculatory encephalopathy is manifested by non-systemic dizziness without vestibular disorders, moderate cerebellar ataxia, periodic headache in the cervical-occipital region. The picture is complemented by tinnitus with a gradual weakening of hearing, pyramidal insufficiency. Cognitive, psychoemotional, vegetative disorders are noted.
Vertebrogenic disorders are considered as part of the clinical picture of vertebral artery syndrome. Symptoms occur suddenly, with sudden movements of the head (overextension, turns to the healthy side, lateral inclinations), clearly depend on the position of the cervical spine. Typical signs are syncope or falls without loss of consciousness (drop attacks), cerebellar syndrome with stato-locomotor ataxia.
Patients report dizziness, noise in the ear, unilateral hearing loss. Transient visual disturbances are represented by a feeling of “sand” or “shroud” in front of the eyes, photopsies. Cephalgias are hemicranic in nature, spread from the cervical occipital to the frontal-temporal-orbital region. With cervicogenic syndromes, pain radiates into the shoulder, arm. Local vegetative reactions (pallor, marble pattern, dryness or hyperhidrosis) are visible on the skin of the cervical region.
Ischemic stroke, accompanied by a clear neurological deficit, is the most significant complication of vertebrobasilar insufficiency. Repeated episodes of acute hemodynamic disorders in such patients occur three times more often than with normal vascular patency. Pronounced stenosis of the arteries can provoke a stem stroke with impaired vital functions. With spondylogenic variants of pathology due to fainting and drop attacks, many patients are injured, including with damage to internal organs.
The basis for the diagnosis of vertebrobasilar insufficiency is the assessment of subjective information (complaints, anamnesis) and physical examination data. Misinterpretation of the causes of vestibulo-atactic syndrome as the most common sign of pathology leads to overdiagnosis, entailing inadequate therapy. In such conditions, an important task is to establish the vascular genesis of symptoms with the help of additional procedures:
- Ultrasound examination. Ultrasound of intracranial and cervical vessels is the method of choice in the primary diagnosis, well visualizes their wall, structure and nature of stenoses. Dopplerography reflects the patency of the arteries, the direction and speed of blood flow. Compression-functional tests allow us to evaluate the resources of collaterals.
- Radiography of the spine. The most accessible method for determining extravasal compression of the vertebral artery is considered radiography of the spine with functional tests. The images are taken in straight and lateral projections with maximum flexion or extension of the cervical spine.
- Tomographic methods. MRI detects even the smallest ischemic foci located in any parts of the central nervous system, therefore it is the most informative method of neuroimaging. The angiography mode, especially in combination with ultrasound, allows a comprehensive assessment of the condition of the main arteries. CT and MRI of the cervical spine provide important data on the vertebrogenic nature of the disease.
In a comprehensive examination, radiopaque angiography (usually with planned operations), radioisotope scintigraphy can be used. The presence of neurological symptoms requires neurophysiological examination – electroencephalography, electronystagmography, analysis of stem evoked potentials. In case of vestibulocochlear syndrome, an otolaryngologist provides diagnostic assistance to a neurologist.
It is necessary to differentiate vertebrobasilar insufficiency with a wide range of conditions. It is distinguished from insufficiency of the carotid basin, hemorrhagic strokes, neuroinfections. With dizziness, it is necessary to exclude Meniere’s disease, labyrinthitis, vestibular neuritis. Patients with drop attacks and syncope with vertebral artery syndrome should be examined for other syncopal conditions, epilepsy, arterial hypotension.
Pathology treatment is carried out according to the general principles of therapy of cerebrovascular disorders, it is a complex multi-level task. Due to the high probability of stroke, urgent hospitalization is indicated for patients with ischemic TIA. Most chronic and spondylogenic forms are treated on an outpatient basis with dynamic supervision. In both cases, conservative measures form the basis of therapy.
Treatment and secondary prevention of repeated episodes of cerebral ischemia involve mandatory correction of risk factors. Patients are recommended to adhere to a low-fat and low-salt diet, normalize body weight, give up bad habits. Regular monitoring of blood pressure and glycemic levels is important. The main role among conservative events is played by the following:
- Pharmacotherapy. Pathogenetically conditioned drug treatment involves vascular, neuroprotective, hypotensive therapy. To normalize the rheological properties of blood, many patients are shown antiplatelet agents, anticoagulants. Symptomatic correction is aimed at eliminating the main clinical manifestations of pathology: dizziness (betahistine, meclozin, dimenhydrinate), headaches (NSAIDs), astheno-neurotic reactions (sedatives, antidepressants).
- Non-drug methods. Non-pharmacological treatment is important for complex therapy and neurorehabilitation. Among the physiotherapy procedures, hyperbaric oxygenation, pulse currents, magnetolaser therapy are used. Patients are shown wearing a fixing collar splint, massage of the cervical-collar zone, physical therapy. Methods of post-isometric muscle relaxation, gentle manual therapy, kinesiotherapy are actively used. The fight against dizziness includes vestibular gymnastics.
The question of surgical intervention is usually considered when conservative therapy is ineffective, sometimes only a radical approach is the only correct one. Given the complexity of access to the affected arteries, reconstructive operations are performed according to strict indications. First of all, we are talking about clinical manifestations of cerebral hypoperfusion, especially stem ischemia caused by hemodynamically significant stenosis (more than 75%), extravasal compression, thromboembolism.
Depending on the nature and extent of the lesion in case of insufficiency of vertebrobasilar blood flow, various operations are performed: endarterectomy, carotid-subclavian bypass surgery and transposition, transluminal angioplasty with stenting. To eliminate extravasal vertebral compression, microdiscectomy with spinal stabilization, laser vaporization, and resection of the cervical rib are performed. When choosing surgical techniques, preference is given to minimally invasive techniques.
For ischemia that is not amenable to other methods of revascularization, methods are being developed for exogenous administration of biologically active molecules that stimulate the development of collateral blood flow in ischemic tissues. One of them involves the use of recombinant angiogenesis inducers (VEGF, FGF–2), the other approach is based on virus-mediated transmission of genes encoding the synthesis of necessary substances. Stem cell therapy is considered a promising method of neovascularization.
Robotic technologies functioning by biofeedback mechanisms are being actively introduced into neurorehabilitation schemes. Dynamic monitoring of physiological parameters while working on the simulator allows the patient to assess his own condition, developing autoregulation skills. By increasing neuroplasticity, the use of such complexes shows high results in restoring motor and cognitive functions.
Prognosis and prevention
The outcome of vertebrobasilar insufficiency is determined by the localization and severity of the stenotic process. A more serious prognosis is noted when the main artery is affected – the annual risk of stroke in such a situation is 20%. For patients who have suffered episodes of cerebral ischemia, preventive therapy with antiplatelet agents, hypotensive, hypolipidemic drugs is extremely important. They are recommended to optimize their lifestyle, monitor blood pressure and carbohydrate metabolism, and undergo regular medical examinations.