Vertebral Basilar Insufficiency - Diagnosis

Physical examination

The characteristics of cochleovestibular disorders are based on the diagnosis of peripheral cochleovestibular syndromes of vascular genesis. Most of the examined patients had bilateral spontaneous nystagmus and only in isolated cases - unilateral. Unilateral nystagmus is usually combined with a harmonious deviation of the arms and trunk towards the slow component of nystagmus, which is typical for peripheral cochleovestibular syndrome in the acute period of the disease. The presence of bilateral nystagmus indicates simultaneous ischemic damage to the peripheral and central vestibular structures. Analysis of the symptoms of combined damage to the inner ear and brain structures (medulla oblongata, pons, midbrain, cerebellum, cerebral hemispheres) showed that in 80% of cases, peripheral cochleovestibular syndrome was formed against the background of symptoms of pons damage. This is due to the single source of blood supply to the peripheral vestibular structures and the central vestibular tracts and nuclei from the branches of the anteroinferior cerebellar artery and the penetrating arteries of the brainstem.

Laboratory research

Experimental vestibular tests in most patients reveal bilateral hyperreflexia (acute period), less often - bilateral hyporeflexia, which corresponds to the period of remission of the disease. Also, this group of patients is characterized by asymmetry in the labyrinth; bilateral vestibular hyperreflexia is combined with unilateral hearing loss, which is the clinical basis for combined (peripheral and central) ischemic damage to the inner ear and brain structures. Asymmetry of nystagmus in direction (a sign of central damage) is usually detected in single patients and indicates simultaneous ischemia of the anterolateral parts of the pons and peripheral cochleovestibular structures. Evaluation of all components of the vestibular reaction (nystagmus, vegetative and sensory manifestations) was characterized by their harmonious correspondence. No disturbances of optokinetic nystagmus were detected in patients with peripheral cochleovestibular syndromes.

Instrumental research

The basis for diagnosing vestibular disorders of vascular genesis is an otoneurological examination with the inclusion of a number of special, objective methods for determining the functional state of the auditory and vestibular analyzers (computer electronystagmography, audiometry, auditory evoked potentials). Otoneurological examination is supplemented by impedance tachooscillography, which allows recording arterial pressure before and after experimental vestibular loads, determining the main parameters of central hemodynamics (stroke and minute volume of circulating blood). Ultrasound Dopplerography and neuroimaging techniques are also used. The results obtained allow us to accurately determine the level of damage to the auditory and vestibular analyzers and identify the features of hemodynamic disorders underlying their formation.

All patients with peripheral cochleovestibular syndromes have hearing impairments detected by audiography. A characteristic feature of hearing impairments is the presence of sensorineural hearing loss, which is bilateral in most patients. Conductive hearing loss is detected in patients with concomitant cicatricial-adhesive middle ear damage. In support of confirmation of conductive hearing loss, tests of sound lateralization in the Weber experiment (towards the worse hearing ear) are used, as well as otoscopy data (cicatricial process of the eardrum) and tympanometry. In some patients, unilateral deafness is detected as a result of acute ischemia of the inner ear.

Acute ischemia of the labyrinth usually develops against the background of various hemodynamic situations, such as asymmetry of the diameters of the vertebral arteries, their hypoplasia in combination with increased arterial pressure, their atherosclerotic stenosis, anomalies of their origin from the aortic arch. Heart rhythm disturbances (paroxysmal tachycardia), venous outflow and increased platelet aggregation and blood viscosity also lead to acute ischemia of the labyrinth.

The development of peripheral cochleovestibular syndromes occurs against the background of organic changes in the brain, of which the most common is the expansion of the subarachnoid space. Focal changes in the hemispheres most often correspond to changes around the cerebral ventricles, characteristic of patients with arterial hypertension. The detected foci of small size in the trunk and cerebellum confirm the otoneurological diagnosis of simultaneous ischemia in various vessels of the vertebral-basilar basin.

Structural changes in the main arteries of the head and hemodynamic parameters of blood flow in the vertebral and internal carotid arteries are examined using ultrasound Dopplerography and duplex scanning; in some cases, transcranial Dopplerography, angiography, and venosinusography are performed. Structural changes in the brain and the state of the cerebrospinal fluid spaces are assessed using CT and MRI of the brain.

Differential diagnostics of vertebrobasilar insufficiency

Vestibular dysfunction of vascular genesis is differentiated from Meniere's disease, neurinoma, multiple sclerosis. In Meniere's disease, attacks of dizziness develop in patients without a history of vascular diseases, vestibular disorders are quickly compensated, and hydrops of the labyrinthine is revealed. In the presence of a neurinoma of the VIII cranial nerve, in addition to the cochleovestibular syndrome, symptoms from the cerebellopontine angle (dysfunction of the V, VII and XIII cranial nerves) are revealed. In multiple sclerosis, the patient's dizziness is long-term, not accompanied by simultaneous auditory disorders, neurological symptoms and central changes are revealed during the study of auditory and visual evoked potentials; foci of demyelination are detected during MRI.

A patient with vestibular dysfunction requires consultation with an obituary specialist, a neuro-ophthalmologist (condition of the vessels of the fundus), ultrasound diagnostics and neuroimaging specialists.

Screening

Screening of this category of patients consists of performing an extended otoneurological examination, including classical otoneurological examination, audiometry and SEP, ultrasound methods of studying the main arteries of the head and neuroimaging methods. To diagnose the level of damage to the vestibular analyzer, a study of spontaneous and experimental vestibular reactions, auditory function and SEP is carried out, the functional state of other cranial nerves (olfactory, trigeminal, facial, glossopharyngeal and vagus) is determined. Peripheral cochleovestibular syndrome is characterized by the absence of focal otoneurological symptoms, the presence of unilateral spontaneous nystagmus, asymmetry of vestibular excitability along the labyrinth, preserved optokinetic nystagmus in combination with peripheral damage to the auditory analyzer. Peripheral vestibular syndrome is characterized by the presence of pathological changes in the main arteries in the form of asymmetries of diameters and hypoplasia of one of the vertebral arteries, as well as the absence of foci of cerebral ischemia in CT and MRI.

Central vestibular syndrome is characterized by the presence of focal otoneurological symptoms, bilateral or multiple spontaneous nystagmus, hyperreflexia and subtentorial nature of vestibular experimental tests, violation of optokinetic nystagmus, in combination with central hearing impairment. Central vestibular syndrome develops against the background of more pronounced changes in the main arteries of the head - stenosis and occlusion of the vertebral artery and internal carotid arteries, leading to a more significant deficit in blood flow in the vessels of the brain, which is accompanied by the presence of foci of ischemia in various parts of the brain.