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Dizziness, vertigo, headaches, vomit, diplopia, blindness, ataxia, imbalance, and weakness in both sides of the body are the most common symptoms. The most frequent cause of the hemodynamic changes leading to VBI is atherosclerosis. The main clinical symptoms are dizziness, vertigo, headaches, vomit, diplopia, blindness, ataxia, imbalance, and weakness in both sides of the body.
Even though arteriography is considered the most important exam to diagnose the disease, the inherent risks of this exam should be taken into consideration. The magnetic resonance angiography has been widely studied and is a good method to identify and localize any occlusions and stenosis in both neck and intracranial great vessels. The first authors to describe its clinical features were Kubic and Adams 1 in The ischemia of the vertebrobasilar circulation clinically presents in one of two possible forms: 1 VBI, or 2 stroke related to the posterior circulation.
Even though VBI is easily suspected when the patient presents with neurological impairment associated to the dizziness, cases presenting with mild imbalance could lead to a wrong diagnosis of other causes of vestibular dysfunction. VBI could cause discrete symptoms, which are related to the ischemia of the inner ear circulation, due to atherosclerosis of the vertebrobasilar arterial system.
The objective of this study is to review the literature regarding the clinical features and diagnosis of VBI, highlighting the available diagnostic testing. We performed a review of the literature study based on a non-systematic database search. The search was performed from June to September, Inclusion criteria were original research, review, cross-section, case-control, case report, cohort, and clinical trial articles. Highly-cited articles published in peer-reviewed, high-impact journals referring to the pathophysiology, diagnosis, and available diagnostic testing for VBI were selected for appraisal.
We excluded studies published in journals who were not peer-reviewed. Then, we read the selected articles in full and excluded articles that did not comply with our inclusion criteria. Our final study group included 24 studies, 14 of which were original research.
Eleven of the studies were published before , and 13 from to Fig. Regarding the location where the studies were conducted, 12 were American, 8 were European, and 4 were Asian Fig. The selected manuscripts that were original research included 12 transversal studies 8 cross-sectional, 3 case-controls, 1 series of cases and two longitudinal studies 1 prospective and 1 retrospective cohort.
The original articles included three descriptions of clinical features of VBI, one demonstrated results of electronystagmography testing, one reported the validity of the vertebral deprivation nystagmus as a diagnostic tool, and 9 compared imaging studies in either controls or patients with VBI 5 studies using magnetic resonance imaging or magnetic resonance angiography, 1 performed angio-tomography in patients with VBI, and 3 reported on Doppler ultrasound results.
From the remaining 10 studies, five were reviews, and the other five were anatomic descriptions. Demographic information of these studies are shown in Table 1. Number of selected studies categorized according to the country where the article was produced. The most frequent cause of the hemodynamic changes that lead to the development of VBI is atherosclerosis. Other common causes are: embolism, atherosclerosis of great vessels, and arterial dissection. Migraine, fibromuscular dysplasia, coagulopathies, and drug abuse are less frequent causes.
Review studies investigating the epidemiology of VBI reported that the prevalence of atherosclerosis and blockage of the vertebrobasilar circulation differ according to the sex and age of the patients. It is more frequently observed in men after the fourth decade of life 8 ; arterial hypertension, obesity, and smoking are considered to be the main risk factors.
Ischemia in the territory of the posterior circulation rarely causes only one symptom at a time through the course of the disease; in most cases, there is an association of different symptoms presenting at the same time.
Grad and Baloh 3 , in a cross-section study involving patients with clinical diagnosis of VBI, stated that the most frequent symptoms in this population were: visual symptoms diplopia, visual hallucinations, deficits in the visual field, and blindness ; drop attacks sudden falls secondary to loss of tonus in the lower limbs, without loss of consciousness ; and muscular incoordination and weakness.
Mental confusion, headaches, hearing loss, paresthesia, dysarthria, and tinnitus are less frequent symptoms. The symptoms usually started within a period that varied from 3 weeks to 3 years prior to the first consultation.
Isolated attacks of dizziness, or even the chronic imbalance that lasts more than 3 weeks are rarely associated with VBI, and are most commonly observed in diabetic patients. Descriptive studies published by Gomez 6 and Grad and Baloh 3 involving only patients with VBI confirmed by impairment on the vertebrobasilar blood flow in the angiography stated that the dizziness complaints of these patients could begin within a time frame ranging from 4 weeks to 4 years, before neurologic signs are clinically observed.
Furthermore, a review study comparing diagnostic testing for early diagnosis of occlusions in the posterior cerebral circulation reported angiography to be the most reliable test for this purpose.
An ongoing research conducted by our group, so far, failed to observe any specific characteristic of the dizziness in patients diagnosed with VBI. Nonetheless, the incidence of changes in other cranial nerves visual complaints, by example seems to be higher. Other possible symptoms of the disease can be secondary to the lateral medullary syndrome, also known as Wallenberg syndrome. This entity is characterized by a stroke in the vertebral artery or PICA irrigation territories in the brainstem.
Symptoms include difficulties swallowing, hoarseness, dizziness, nausea and vomiting, nystagmus, and imbalance and gait incoordination. Several anatomic studies reported the complexity of the irrigation pattern of the vestibular system, and suggested that fact to play a major role in the pathophysiologic mechanism of the VBI presenting with labyrinthic symptoms.
The PICA is a terminal vessel with very few collateral branches. The IAA irrigates the cochleovestibular nerve, the cochlea, and the posterior labyrinth. Considering that the labyrinthine branches are smaller and receive less collateral irrigation, it is possible that the labyrinth should be more affected by atherosclerotic blockage of the vertebrobasilar arterial system.
On the other hand, the cochlea receives collateral irrigation from the carotid artery, supplying adjacent portions of the petrous bone. This particular feature prevents the cochlea from suffering ischemic symptoms in the case of a vascular insufficiency. Moubayed and Saliba, 5 in a double-blind retrospective cohort, studied the prevalence of positional dizziness and imbalance, plus clinical and electronystagmography findings in two groups: one with changes in the vertebral arteries in magnetic resonance angiography stenotic or hypoplastic vertebral arteries and one without any changes.
The authors observed no differences between the two groups. These results suggest that the clinical symptoms are triggered by occlusion or obstruction in smaller vessels, in more distal regions. Isolated episodes of vertigo could arise from transient ischemia of the vestibular labyrinth, due to the characteristics of its terminal circulation without collateral vessels.
Thus, the vestibular system could be more sensitive in detecting differences in the action potential secondary to ischemia. The ischemia could affect both peripheral and central structures of the vestibular system. Moubayed and Saliba 5 describe two mechanisms through which the ischemic episodes could cause isolated dizziness spells: 1 decrease in the blood flow to the vestibular nuclei or to the root of the entrance zone of the vestibulo-cochlear nerve; and 2 direct ischemia of the labyrinth.
The patients with a suspected diagnosis of transient ischemic attacks or vertebrobasilar strokes should undergo neuroimaging tests. Even though arteriography is considered to be the most important exam for this purpose, the risks of performing this test in patients with VBI should be taken in consideration.
Many patients choose not to take this test after reading the risks of the procedure in the informed consent terms. The main complications of the arteriography are: local complications of the arterial catheters; regional low blood flow; and stroke.
The magnetic resonance angiography MRA has been widely studied and it is considered to be a good method to identify and localize any occlusions and stenosis in both neck and intracranial great vessels. In one of those studies, Nakagawa et al 18 reported that stenosis of the basilar artery was a significant finding among patients with the diagnosis of VBI when compared with age-matched controls.
Moubayed and Saliba 5 evaluated patients with positional dizziness and imbalance regarding the morphology of the vertebral arteries, risk factors for stroke involving the posterior circulation, and evolution of the symptoms over time in patients with VBI compared with controls.
They concluded that Kim et al 19 dedicated a study to evaluating the prevalence of occlusion and stenosis in the proximal segments of the vertebral arteries, comparing the results with changes of the distal segments. The authors performed magnetic resonance arteriography in patients divided in 6 different groups: 1 asymptomatic volunteers; 2 lesser symptoms, such as: headaches, tinnitus, seizures, movement disorders, anxiety, dementia, traumatic head injuries, or symptoms of transitory ischemia; 3 patients with occlusion or stenosis of the coronary arteries; 4 patients with previous intracranial bleeding; 5 patients with stroke of the anterior circulation; and 6 patients with stroke related to the posterior circulation.
The authors also consider the proximal region of the vertebral arteries to be the place with a higher prevalence of occlusion of the posterior circulation. They also state that more studies focusing on understanding the natural history of these lesions and their evolution over time are still needed.
A small number of publications dedicated on evaluating posterior circulation; however, studies in healthy patients points toward angio-tomography and MRA to reach similar sensibility and specificity levels, especially when studying the basilar artery. Other studies in healthy subjects reported the sensibility of the magnetic resonance angiography, angio-tomography, and transcranial Doppler to be The transcranial Doppler is a cheap, pain-free, and non-invasive test, which is capable of measuring the speed and direction of the blood flow from the proximal areas of the great intracranial arteries.
The first clinical application of this exam was described in Another important piece of information given by the Doppler is the pulsatility index PI , which is the relation between the measured speed of the blood flow during the systolic pulse and the final diastolic pulse. Studies in the general healthy population demonstrated that the lower this relation, the greater the resistance of the adjacent microvasculature. This index is highly predictive of early hemodynamic intracranial changes.
It is known that the speed of the intracranial arterial blood flow decreases and PI increases in older male patients, even in those without any cerebrovascular diseases.
The opposite phenomenon is observed in female patients: the speed increases and PI decreases. It has also been demonstrated that there were no differences among different ethnic groups, regarding the blood flow speed and PI of the posterior circulation.
This nystagmus would occur because of a decrease in the blood flow in the opposite vertebral artery because of the head rotation. Moubayed and Saliba 5 reported the physiopathology of this event to be secondary to the depolarization of the ciliated cells, caused by an acute onset of ischemia, generating a nystagmus.
However, in a late phase of the ischemic injury, the membrane of the axons become incapable of excitation, resulting in a hypofunction of these cells. Nonetheless, this explanation is controversial, because if the basilar artery has a normal blood flow, there would be no reason for decreased perfusion of the terminal circulation.
Inui et al 14 reported the case of a patient showing nystagmus when turning the head to the left side, and exams pointed to an occlusion of the ipsilateral vertebral artery. This suggests a decrease in the blood flow on the right vertebral artery; the decreased blood flow in the occluded left artery was not enough to supply the basilar artery, generating the nystagmus. Bottino 26 studied patient with clinical symptoms of VBI and compared with patients without any kind of disease.
He observed the presence of NPVB in In the same study, the authors also report the results of Doppler of the carotid and describe vertebral arteries in 21 patients with nystagmus secondary to vertebrobasilar deprivation.
The authors conclude that using this clinical maneuver is a cheap, sensitive, and safe procedure to diagnose VBI. This study has several limitations. The small number of good randomized, double-blind, clinical trials, and well-designed case-control and cohort studies limits interpretation and validity of some of the results. The high variability of measures and outcomes among the studies about the same diagnostic testing, anatomic feature, or patients selected as control groups, were also limiting factors in our analysis.
Nonetheless, we were able to provide a meaningful review including several aspects of the pathophysiology and available diagnostic testing for VBI. VBI should be suspected in patients presenting with risk factors for ischemia and vestibular symptoms. Each diagnostic test offers different pros and cons, thus, each patient should be treated individually to avoid possible sequels.
National Center for Biotechnology Information , U. Journal List Int Arch Otorhinolaryngol v. Int Arch Otorhinolaryngol.
Published online Oct Author information Article notes Copyright and License information Disclaimer. Received Mar 26; Accepted Aug This article has been cited by other articles in PMC.
Dizziness, vertigo, headaches, vomit, diplopia, blindness, ataxia, imbalance, and weakness in both sides of the body are the most common symptoms. The most frequent cause of the hemodynamic changes leading to VBI is atherosclerosis. The main clinical symptoms are dizziness, vertigo, headaches, vomit, diplopia, blindness, ataxia, imbalance, and weakness in both sides of the body. Even though arteriography is considered the most important exam to diagnose the disease, the inherent risks of this exam should be taken into consideration.
Pathophysiology and Diagnosis of Vertebrobasilar Insufficiency: A Review of the Literature
Vertebrobasilar insufficiency is largely caused by atherosclerosis , and shares many of the same risk factors as other atherosclerotic disease. Patients with vertebrobasilar insufficiency will present with symptoms related to ischemia of the posterior circulation. The most common symptoms include:. Patient most commonly present with multiple symptoms, which are often short-lived and reproducible 1. A classic description of vertebrobasilar insufficiency is that of reproducible symptoms that occur with head rotation. The vertebral arteries join to form the basilar artery which forms the posterior circulation of the brain.