Contribution of intracranial vertebral artery asymmetry to vestibular neuropathy

Vertebral artery hypoplasia and hemodynamic impairment in transient global amnesia: a case control study

Introduction

The aetiology of transient global amnesia (TGA) is still a matter of debate. Besides ischemia of the mesial temporal lobe including the hippocampus, migraine-like mechanisms, epileptic seizures affecting mnestic structures, or venous congestion in the (para) hippocampal area due to jugular vein insufficiency have been discussed. We assessed the diameters of the intracranial arteries of TGA patients compared to controls to identify differences that support the hypothesis of reduced hippocampal perfusion as a pivotal factor in the pathophysiology of TGA.

Methods

We reviewed magnetic resonance imaging time of flight angiographies (TOF-MRA) that were acquired during in-patient treatment of 206 patients with acute TGA.

Results

The diameters of the vertebral artery (VA) in the V4 segment, the proximal basilar artery, and the internal carotid arteries were measured manually. We compared the findings with TOF-MRA images of an age and sex matched control group of neurological patients without known cerebrovascular pathology. In TGA patients the diameter of the right VA was significantly (p < 0.01) smaller compared to controls (2.09 mm vs. 2.35 mm). There were no significant differences in the diameters of the other vessels. Only the fetal variant of the posterior cerebral artery was slightly more common in TGA.

Discussion

The smaller diameter (hypoplasia) of the right VA supports the hypothesis of a contribution of hemodynamic factors to the pathophysiology of TGA. The fact that hypoplasia represents a congenital condition might be the explanation why previous studies failed to find an increased rate of the classical (acquired) vascular risk factors.

The prevalence and clinical significance of intracranial vertebral artery terminated in posterior inferior cerebellar artery: A multicenter hospital-based study in China

Objective

Intracranial vertebral artery terminated in the posterior inferior cerebellar artery (PICA-VA) is the most popular variant of the posterior inferior cerebellar artery, while its prevalence and clinical significance remained unclear. In the present study, we aimed to investigate the prevalence and clinical significance of PICA-VA.

Methods

This was a multicenter hospital-based cross-sectional study. Patients were enrolled for cerebral MRI and MRA within 1 week of stroke onset. Clinical characteristics were recorded. PICA-VA is termed as a vertebral artery that does not communicate with the basilar artery but terminates in an ipsilateral PICA. We observed the prevalence of PICA-VA and identified a relationship between PICA-VA and vertebrobasilar stroke.

Results

From 1 August 2015 to 31 May 2017, a total of 2,528 patients were enrolled in the present study. Among them, 95 patients (3.76%, 95/2,528) had the variation of PICA-VA, 51 of which (53.7%) were located on the right side. The prevalence of vertebrobasilar stroke was considerably higher in patients with PICA-VA than those without (40.2%, 37/92 vs. 17.1%, 417/2,436, p < 0.01). PICA-VA was an independent risk for vertebrobasilar stroke after being adjusted for a history of intracranial hemorrhage, diabetes, body mass index, and triglyceride.

Conclusion

The present study showed that 3.76% of patients with acute stroke had PICA-VA, which independently increased the risk of acute vertebrobasilar stroke.

Different results of vestibular examinations and blood flow in cases with transient vascular vertigo/dizziness with or without central nervous system symptoms

BACKGROUND

The condition of vestibular dysfunction and blood flow in the vertebral artery (VA) in transient vascular vertigo/dizziness (TVV) is not well established.

OBJECTIVES

To clarify the pathophysiology of TVV, especially the difference between the isolation of vestibular symptoms.

MATERIALS AND METHODS

Ten TVV patients with central nervous system symptoms (TVVw) and 12 TVV patients without central nervous system symptoms (TVVo) underwent duplex color-coded ultrasonographic evaluation of VAs, caloric test, and cervical vestibular-evoked myogenic potential (cVEMP).

RESULTS

The mean flow velocity (MV) ratio (peak MV of contralateral VA divided by target VA) was significantly higher in TVVw than in TVVo. There was no difference in the occurrence of canal paresis between TVVw and TVVo. Abnormal asymmetry ratios (ARs) of cVEMP were observed only in TVVo cases (6 of 12 cases), revealing a statistically significant difference in the number of cases between TVVw and TVVo.

CONCLUSIONS AND SIGNIFICANCE

Measuring VAs using duplex color-coded ultrasonography and cVEMP may help evaluate TVV. Different results of MV ratio and cVEMP between TVV cases with or without central nervous system symptoms may indicate differences in the pathophysiology between TVVw and TVVo.

Vascular mechanisms in acute unilateral peripheral vestibulopathy: a systematic review

Acute unilateral peripheral vestibulopathy (AUPVP) is a frequent cause of vestibular loss. Several aetiologies have been proposed, but the exact mechanism remains unknown. The aim of this study is a systematic analysis of the literature evaluating the vascular aetiology of AUPVP. A systematic literature search was performed in PubMed, Cochrane Library and Embase, including articles published from January 1^st, 2010 to November 30^th, 2020. Two reviewers independently selected articles investigating a link between AUPVP and vascular disease. The following information was extracted: year of publication, country, level of evidence, assessed vascular risk factors and number of patients. A total of 450 articles was obtained. Eleven articles were retained with 100% agreement between the two reviewers. In a pooled population of 805 patients, the main results were the higher neutrophil to lymphocyte ratio and higher prevalence of vascular risk factors among AUPVP patients. A meta-analysis was not performed because the studies were too heterogeneous in terms of methodology. Indirect arguments for vascular mechanisms in AUPVP were found. These findings indicate that larger prospective well-controlled studies are needed to clarify the vascular aetiology of AUPVP.

Detection of intralabyrinthine abnormalities using post-contrast delayed 3D-FLAIR MRI sequences in patients with acute vestibular syndrome

PURPOSE

3D-FLAIR sequences with delayed acquisition after contrast medium injection have demonstrated new insights into blood-labyrinthine barrier (BLB) abnormalities in various diseases. The aim of this study was to assess the BLB in patients referred with unilateral acute vestibular syndrome (UAVS).

MATERIALS AND METHODS

In this retrospective multicenter imaging study, we performed 3D-FLAIR and steady-state free precession (SSFP) sequences 4 h after contrast medium administration in 26 healthy volunteers and in 30 patients with UAVS. Two radiologists, blinded to the clinical data, independently assessed the asymmetrical enhancement of the labyrinthine structures and the vestibular nerve on 3D-FLAIR sequences, and the signal of the labyrinthine structures on SSFP sequences. Inter-reader agreement tests were performed.

RESULTS

An asymmetrical enhancement of the semicircular canals was observed in 26 out of 30 ears (86.6%, p < 0.001) and never observed in healthy subjects. An asymmetrical enhancement of the vestibular nerve was never observed in either patients or healthy subjects. An asymmetrical enhancement of the cochlea was observed on the 3D-FLAIR sequence in 6 out of 30 ears only in the patients' group (20%, p = 0.03) and always associated with an enhancement of at least one semicircular canal. A low signal on SSFP sequences was observed only in 11 out of 30 symptomatic ears (36.7%, p < 0.001), involving the utricle in 7 ears and the superior semicircular canal in 4 ears.

CONCLUSION

Patients with typical UAVS presented with semicircular canal enhancement on MRI, while an asymmetrical enhancement of the vestibular nerve was not displayed.

TRIAL REGISTRATION

NCT02529475 KEY POINTS: • Patients with typical vestibular neuronitis presented with semicircular canal enhancement on MRI in 87% of cases. • An enhancement of the vestibular nerve was never displayed.

Duplicated and Hypoplastic V4 Segment of Vertebral Artery along with Duplication of Anterior Inferior Cerebellar Artery: A Case Report

Variations of V3 and V4 segments of Vertebral Artery (VA) are very rare. We report an extremely rare case of hypoplastic and duplicated V4 segment of right VA along with variant origin of right Anterior Inferior Cerebellar artery (AICA) from right Posterior Inferior Cerebellar artery (PICA). AICA was duplicated, with one vessel arising from PICA and another arising from distal Hypoplastic Vertebral Artery (HVA). HVA should be considered for the diagnosis of acute stroke of brainstem and cerebellum. Knowledge about VA variations is important to prevent iatrogenic injuries during surgeries involving posterior cranial fossa.

Vertebral Artery Diameter and Flow: Nature or Nurture

BACKGROUND AND PURPOSE

In contrast with the carotid arteries, the vertebral arteries (VAs) show considerable variation in length, caliber, and vessel course. This study investigated whether the variation in diameter and flow characteristics of the VAs might be inherited.

METHODS

A total of 172 Italian twins from Padua, Perugia, and Terni (54 monozygotic, 32 dizygotic) recruited from the Italian Twin Registry underwent B-mode and pulsed-wave Doppler ultrasound assessment of their VAs. VA diameters, peak systolic velocity (PSV) and end diastolic velocity (EDV) were assessed at the level of a horizontal V2 segment. Univariate quantitative genetic modeling was performed.

RESULTS

Fourteen percent of the sample had VA hypoplasia. Within pair correlation in monozygotic twins was higher than in dizygotics (.552 vs. .229) for VA diameter. Age- and sex-adjusted genetic effect, under the most parsimonious model, accounted for 54.7% (95% CI: 42.2-69.1%) of the variance of VA diameter, and unshared environmental effect for 45.3% (95% CI: 30.9-57.8%). No heritability was found for the PSV of VA, but shared (34.1%; 95% CI: 16.7-53.7%) and unshared (65.9%; 95% CI: 45.9-83.1%) environmental factors determined the variance. EDV of VA is moderately genetically influenced (42.4%; 95% CI: 16.1-64.9%) and also determined by the unshared environment (57.6%; 95% CI: 34.7-83.7%).

CONCLUSIONS

The diameter of the VAs is moderately genetically determined. Different factors influence the PSV and EDV of VAs, which may highlight the complex hemodynamic background of VA flow and help to understand the vertebral flow anomalies found by ultrasound.

Ischemia as a potential etiologic factor in idiopathic unilateral sudden sensorineural hearing loss: Analysis of posterior circulation arteries

The association between idiopathic sudden sensorineural hearing loss (ISSNHL) and the radiologic characteristics of the vertebrobasilar artery is unclear. We hypothesized that the degree and direction of vertebrobasilar artery curvature in the posterior circulation contribute to the occurrence of ISSNHL. We consecutively enrolled patients diagnosed with unilateral ISSNHL in two tertiary hospitals. Magnetic resonance images were performed in all patients to exclude specific causes of ISSNHL, such as vestibular schwannoma, chronic mastoiditis, and anterior inferior cerebellar artery infarct. We measured the following parameters of posterior circulation: vertebral and basilar artery diameter, the degree of basilar artery curvature (modified smoker criteria), and vertebral artery dominance. Pure tone audiometries were performed at admission and again 1 week and 3 months later. A total of 121 ISSNHL patients (mean age, 46.0 ± 17.3 years; 48.8% male) were included in these analyses. The proportion of patients with the left side hearing loss was larger than the proportion with the right side hearing loss (left, 57.9%; right, 42.1%). The majority of patients were characterized by a left dominant vertebral artery and right-sided basilar artery curvature. The direction of the basilar artery curvature was significantly associated with hearing loss lateralization (p = 0.036). Age and sex matched multivariable analyses revealed the absence of diabetes and right-sided basilar artery curvature as significant predictors for left sided hearing loss. There was no statistical difference between atherosclerotic cardiovascular risk score (high versus low) and hearing outcomes at 3 months. In ISSNHL, the laterality of hearing loss was inversely associated with the direction of basilar artery curvature. Our results, therefore, indicate the importance of vascular assessment when evaluating ISSNHL.

[Isolated functional loss of the lateral semicircular canal in vestibular neuritis]

Today, modern tools in vestibular testing are feasible to provide information about functional status of all five peripheral vestibular receptors. Isolated or combined loss of crista and macula receptor function can be determined in the diagnostic process. We describe a seldom case of isolated functional loss of lateral semicircular canal receptor function in a 55-year-old patient. Whereas there was no ispilateral caloric response and video head impulse test revealed a catch-up saccade, air-conducted (AC) cervical and ocular vestibular-evoked myogenic potentials (cVEMP, oVEMP), subjective visual vertical and MRI were normal.

Vestibulopathy after a modified Blalock-Taussig procedure in a cyanotic congenital heart disease patient

Vestibulopathy is a condition characterized by the onset of vertigo, nausea and vomiting, in the absence of hearing loss or tinnitus. The differential diagnosis includes peripheral otologic disorders and central disorders such as vascular insufficiency. Modified Blalock-Taussig (B-T) shunt, a polytetrafluoroethylene graft from the subclavian artery to the pulmonary artery, has become the palliative procedure of choice in cyanotic congenital heart disease patients. This palliative surgery creates a similar vascular haemodynamic to that seen in the subclavian steal syndrome and when associated with aplasia, hypoplasia or stenosis of the contralateral carotid, vertebral or posterior communicating arteries it may predispose to vascular hypoperfusion and peripheral hypofunctioning of the vestibular system. We report the case of a cyanotic congenital heart disease patient with vertigo and dizziness who underwent a modified B-T fistula on childhood and developed, many years later, a vertiginous syndrome probably of vascular origin.