Isolated vestibular syndromes due to brainstem and cerebellar lesions

Central Positional Nystagmus Can Be the Sole Presentation of Cerebellar Nodulus Infarction

OBJECTIVES

To draw attention to acute positional vertigo and central positional nystagmus (CPN) developing as the sole features of cerebellar nodulus infarction.

BACKGROUND

The cerebellar nodulus is vascularized by the medial branch of the posterior inferior cerebellar artery, which also supplies the uvula, tonsil, tuber, and pyramid of the vermis, and the inferior part of the cerebellar hemisphere, making isolated cerebellar nodulus infarction extremely rare. CPN occurs after a change in head position with respect to gravity and is caused by pathologies involving the vestibulo-cerebellar pathways. CPN is rarely seen in isolation. Additional neurological signs and ocular motor abnormalities are generally present.

METHODS

A 62-year-old man was admitted to the emergency department with acute-onset positional vertigo and CPN as the sole finding on examination. Cranial magnetic resonance imaging revealed an acute infarction involving the nodulus. Results: Infarcts restricted to nodulus can cause positional vertigo and CPN without any associated neurological signs or ocul ar motor abnormalities.

CONCLUSION

Though very rare, cerebellar nodulus stroke must be searched in patients with positional vertigo of acute onset and isolated CPN on examination.

Prospective analysis of video head impulse tests in patients with acute posterior circulation stroke

Background

Video head impulse tests (vHITs), assessing the vestibulo-ocular reflex (VOR), may be helpful in the differential diagnosis of acute dizziness. We aimed to investigate vHITs in patients with acute posterior circulation stroke (PCS) to examine whether these findings could exhibit significant abnormalities based on lesion locations, and to evaluate diagnostic value of vHIT in differentiating dizziness between PCS and vestibular neuritis (VN).

Methods

We prospectively recruited consecutive 80 patients with acute PCS and analyzed vHIT findings according to the presence of dorsal brainstem stroke (DBS). We also compared vHIT findings between PCS patients with dizziness and a previously studied VN group (n = 29). Receiver operating characteristic (ROC) analysis was performed to assess the performance of VOR gain and its asymmetry in distinguishing dizziness between PCS and VN.

Results

Patients with PCS underwent vHIT within a median of 2 days from stroke onset. Mean horizontal VOR gain was 0.97, and there was no significant difference between PCS patients with DBS (n = 15) and without (n = 65). None exhibited pathologic overt corrective saccades. When comparing the PCS group with dizziness (n = 40) to the VN group (n = 29), patients with VN demonstrated significantly lower mean VOR gains in the ipsilesional horizontal canals (1.00 vs. 0.57, p < 0.001). VOR gain and their asymmetry effectively differentiated dizziness in the PCS from VN groups, with an area under the ROC curve of 0.86 (95% CI 0.74-0.98) and 0.91 (95% CI 0.83-0.99, p < 0.001), respectively.

Conclusion

Significantly abnormal vHIT results were rare in patients with acute PCS, even in the presence of DBS. Moreover, vHIT effectively differentiated dizziness between PCS and VN, highlighting its potential for aiding differential diagnosis of acute dizziness.

Cerebral blood flow in patients recovered from mild COVID-19

BACKGROUND AND PURPOSE

Cerebral hypoperfusion has been described in both severe and mild forms of symptomatic Coronavirus Disease 2019 (COVID-19) infection. The purpose of this study was to investigate global and regional cerebral blood flow (CBF) in asymptomatic COVID-19 patients.

METHODS

Cases with mild COVID-19 infection and age-, sex-, and race-matched healthy controls were drawn from the Aging Brain Consortium at The University of South Carolina data repository. Demographics, risk factors, and data from the Montreal Cognitive Assessment were collected. Mean CBF values for gray matter (GM), white matter (WM), and the whole brain were calculated by averaging CBF values of standard space-normalized CBF image values falling within GM and WM masks. Whole brain region of interest-based analyses were used to create standardized CBF maps and explore differences between groups.

RESULTS

Twenty-eight cases with prior mild COVID-19 infection were compared with 28 controls. Whole-brain CBF (46.7 ± 5.6 vs. 49.3 ± 3.7, p = .05) and WM CBF (29.3 ± 2.6 vs. 31.0 ± 1.6, p = .03) were noted to be significantly lower in COVID-19 cases as compared to controls. Predictive models based on these data predicted COVID-19 group membership with a high degree of accuracy (85.2%, p < .001), suggesting CBF patterns are an imaging marker of mild COVID-19 infection.

CONCLUSION

In this study, lower WM CBF, as well as widespread regional CBF changes identified using quantitative MRI, was found in mild COVID-19 patients. Further studies are needed to determine the reliability of this newly identified COVID-19 brain imaging marker and determine what drives these CBF changes.

Isolated transient vertigo due to TIA: challenge for diagnosis and therapy

As a prevalent vertigo disease in the clinic, isolated transient vertigo can present as a vertigo episode without focal signs and always free of symptoms on presentation. Previous studies showed a part of isolated transient vertigo events had a high risk of stroke during follow-up. However, how to discern posterior circulation ischemia become a great challenge for clinicians, especially in emergency, neurology, and ENT departments. Routine besides, hematological, and imaging examinations are often difficult provide a clear etiological diagnosis. Hence, this article reviews current knowledge about the epidemiology, risk factors, offending lesions, and clinical manifestation of transient ischemic attack (TIA) presenting as isolated transient vertigo. In addition, we summarize several advances in besides examinations, serum biomarkers, and imaging technologies to better identify stroke events. Finally, the current situation of therapy was briefly retrospected. Here we present a critical clinical puzzle that needs to be solved in the future. Of note, there is a still lack of high-quality studies in this field. The article reviews the keys to the diagnosis of isolated transient vertigo due to TIA and provides us with more methods to screen for high-risk stroke populations.

Diagnosing and localizing the acute vestibular syndrome - Beyond the HINTS exam

When assessing the acutely dizzy patient, the HINTS 'Plus' (Head Impulse, Nystagmus, Test of Skew, 'Plus' a bedside assessment of auditory function) exam is a crucial component of the bedside exam. However, there are additional ocular motor findings that can help the clinician distinguish peripheral from central etiologies and enable accurate localization, especially when the patient has acute dizziness, vertigo and/or imbalance but without spontaneous nystagmus. We will review the literature on these findings which are 'beyond HINTS' and include saccades/ocular lateropulsion, smooth pursuit, and provocative maneuvers including head-shaking and positional testing (not part of the HINTS exam). Additionally, we will expound on the localizing value of nystagmus, ocular alignment and the ocular tilt reaction (parts of the HINTS exam). The paper has been organized neuroanatomically, based on brainstem and cerebellar structures that have been reported to cause the acute vestibular syndrome.

Vertigo in Acute Stroke Is a Predictor of Brain Location but Is Not Related to Early Outcome: The Experience of Sagrat Cor Hospital of Barcelona Stroke Registry

BACKGROUND

Vertigo is an uncommon symptom among acute stroke victims. Knowledge about the clinical profile, the brain location, and the early outcome in stroke patients with cerebrovascular diseases and vertigo remains limited.

OBJECTIVES

In this study, the effects of vertigo on cerebral topography and early prognosis in cerebrovascular diseases were investigated.

METHODS

A comparative analysis in terms of demographics, risk factors, clinical characteristics, stroke subtypes, cerebral and vascular topography, and early outcome was performed between patients with presence or absence of vertigo on a sample of 3743 consecutive acute stroke patients available from a 24-year ongoing single-center hospital-based stroke registry.

RESULTS

Vertigo was present in 147 patients (3.9%). Multiple logistic regression analysis showed that variables independently associated with vertigo were: location in the cerebellum (OR 5.59, CI 95% 3.24-9.64), nausea or vomiting (OR 4.48, CI 95% 2.95-6.82), medulla (OR 2.87, CI 95% 1.31-6.30), pons (OR 2.39, CI 95% 1.26-4.51), basilar artery (OR 2.36, CI 95% 1.33-4.17), ataxia (OR 2.33, CI 95% 1.41-3.85), and headache (OR 2.31, CI 95% 1.53-3.49).

CONCLUSION

The study confirmed that the presence of vertigo was not related with increased in-hospital mortality or poor prognosis at hospital discharge. Vertigo is mainly related to non-lacunar vertebrobasilar stroke with topographic localization in the cerebellum and/or brainstem.

Vascular vertigo and dizziness: Diagnostic criteria

This paper presents diagnostic criteria for vascular vertigo and dizziness as formulated by the Committee for the Classification of Vestibular Disorders of the Bárány Society. The classification includes vertigo/dizziness due to stroke or transient ischemic attack as well as isolated labyrinthine infarction/hemorrhage, and vertebral artery compression syndrome. Vertigo and dizziness are among the most common symptoms of posterior circulation strokes. Vascular vertigo/dizziness may be acute and prolonged (≥24 hours) or transient (minutes to  < 24 hours). Vascular vertigo/dizziness should be considered in patients who present with acute vestibular symptoms and additional central neurological symptoms and signs, including central HINTS signs (normal head-impulse test, direction-changing gaze-evoked nystagmus, or pronounced skew deviation), particularly in the presence of vascular risk factors. Isolated labyrinthine infarction does not have a confirmatory test, but should be considered in individuals at increased risk of stroke and can be presumed in cases of acute unilateral vestibular loss if accompanied or followed within 30 days by an ischemic stroke in the anterior inferior cerebellar artery territory. For diagnosis of vertebral artery compression syndrome, typical symptoms and signs in combination with imaging or sonographic documentation of vascular compromise are required.

Comparative study of vestibular projection pathway connectivity in cerebellar injury patients and healthy adults

Objective

Cerebellar injury can not only cause gait and postural instability, nystagmus, and vertigo but also affect the vestibular system. However, changes in connectivity regarding the vestibular projection pathway after cerebellar injury have not yet been reported. Therefore, in the current study, we investigated differences in the connectivity of the vestibular projection pathway after cerebellar injury using diffusion tensor imaging (DTI) tractography.

Methods

We recruited four stroke patients with cerebellar injury. Neural connectivity in the vestibular nucleus (VN) of the pons and medulla oblongata in patients with cerebellar injury was measured using DTI. Connectivity was defined as the incidence of connection between the VN on the pons and medulla oblongata and target brain regions such as the cerebellum, thalamus, parieto-insular vestibular cortex (PIVC), and parietal lobe.

Results

At thresholds of 10 and 30, there was lower connectivity in the ipsilateral hemisphere between the VN at the medullar level and thalamus in the patients than in healthy adults. At a threshold of 1 and 10, the patient group showed lower VN connectivity with the PIVC than healthy adults. At a threshold of 1, VN connectivity with the parietal lobe in the contralateral hemisphere was lower in the patients than in healthy adults. Additionally, at a threshold of 30, VN connectivity at the pons level with the cerebellum was lower in healthy adults than in the patients.

Conclusion

Cerebellar injury seems to be associated with decreased vestibular projection pathway connectivity, especially in the ipsilateral thalamus, PIVC, and contralateral parietal lobe.

Enhancement of capability for motor imagery using vestibular imbalance stimulation during brain computer interface

Objective.Motor imagery (MI), based on the theory of mirror neurons and neuroplasticity, can promote motor cortical activation in neurorehabilitation. The strategy of MI based on brain-computer interface (BCI) has been used in rehabilitation training and daily assistance for patients with hemiplegia in recent years. However, it is difficult to maintain the consistency and timeliness of receiving external stimulation to neural activation in most subjects owing to the high variability of electroencephalogram (EEG) representation across trials/subjects. Moreover, in practical application, MI-BCI cannot highly activate the motor cortex and provide stable interaction owing to the weakness of the EEG feature and lack of an effective mode of activation.Approach.In this study, a novel hybrid BCI paradigm based on MI and vestibular stimulation motor imagery (VSMI) was proposed to enhance the capability of feature response for MI. Twelve subjects participated in a group of controlled experiments containing VSMI and MI. Three indicators, namely, activation degree, timeliness, and classification accuracy, were adopted to evaluate the performance of the task.Main results.Vestibular stimulation could significantly strengthen the suppression ofαandβbands of contralateral brain regions during MI, that is, enhance the activation degree of the motor cortex (p< 0.01). Compared with MI, the timeliness of EEG feature-response achieved obvious improvements in VSMI experiments. Moreover, the averaged classification accuracy of VSMI and MI was 80.56% and 69.38%, respectively.Significance.The experimental results indicate that specific vestibular activity contributes to the oscillations of the motor cortex and has a positive effect on spontaneous imagery, which provides a novel MI paradigm and enables the preliminary exploration of sensorimotor integration of MI.

Vertigo and dizziness in the emergency room

PURPOSE OF REVIEW

To provide an update on diagnostic algorithms for differential diagnosis of acute vertigo and dizziness and swift identification of potentially harmful causes.

RECENT FINDINGS

About 25% of patients with acute vertigo and dizziness have a potentially life-threatening diagnosis, including stroke in 4-15%. Diagnostic work-up relies on the combination of symptom features (triggers, duration, history of vertigo/dizziness, accompanying symptoms) and a comprehensive vestibular, ocular motor, and balance exam. The latter includes head impulse, head-shaking nystagmus, positional nystagmus, gaze-holding, smooth pursuit, skew deviation, and Romberg's test. Recent standardized diagnostic algorithms (e.g., HINTS, TriAGe+) suggest the combination of several elements to achieve a good diagnostic accuracy in differentiation of central and peripheral vestibular causes. Neuroimaging with MRI must be applied and interpreted with caution, as small strokes are frequently overlooked, especially in the acute setting (false-negative rate of up to 50%).

SUMMARY

Diagnostic differentiation of acute vertigo and dizziness remains a complex task, which can be tackled by a structured clinical assessment focusing on symptom characteristics and constellations of ocular motor and vestibular findings. Specific challenges arise in cases of transient or atypical vestibular syndromes.

Application of neutrophil to lymphocyte ratio to identify CT-negative cerebral infarction with nonfocal symptoms

Background

The neutrophil to lymphocyte ratio (NLR) has emerged as a strong predictor of mortality in stroke patients. Our study aimed to investigate the correlation between NLR and cerebral infarction with nonfocal symptoms confirmed by diffusion-weighted imaging (DWI) (+).

Methods

A total of 439 patients with nonfocal stroke symptoms with CT-negative findings were included from January 1 to December 31, 2018. All patients underwent a head MRI examination within seven days following a head CT examination. The patients’ demographics, medical history, presenting symptoms, and stroke location were recorded. Logistic regression and receiver operating characteristic (ROC) curve analysis were used to identify variables with a significant association with cerebral infarction.

Results

Cerebral infarction was detected in 79 (18%) patients confirmed by DWI(+), located mostly in the cerebellum (40.51%). Dizziness (85.19%) was the most common symptom. The cerebral infarction group showed a higher prevalence of hypertension (P<0.0001), diabetes mellitus (P<0.0001), and smoking status (P=0.001) than non-cerebral infarction group. The NLR (P<0.0001) was higher in the cerebral infarction group. There was no significant difference in NIHSS (P=0.09). Logistic analysis revealed that male gender (P=0.046), a history of hypertension (P=0.001), diabetes mellitus (P=0.001), smoking (P=0.023), and NLR (P<0.0001) were the best predictors of cerebral infarction. When integrating sex, hypertension, diabetes mellitus, smoking and NLR, the area under ROC value of the combined method was 0.785, higher than any separate parameters (P<0.05).

Conclusions

NLR combined with male gender, a history of hypertension, diabetes mellitus, and smoking, could predict DWI-confirmed cerebral infarction with nonfocal neurologic symptoms with high diagnostic accuracy.

Carotico-vertebral Doppler Ultrasonography in Patients with Idiopathic Vertigo

BACKGROUND

In the present study, we investigated the relationship between caroticovertebral Doppler USG measurement results and Vertigo Symptom Scale-Short Form (VSS-SF) in patients with idiopathic vertigo.

METHODS

Fifty patients with idiopathic vertigo and 30 healthy subjects were included into the study. Ear, Nose & Throat (ENT) examination, audiological examination, routine hemogram, biochemichal tests and temporal magnetic resonance imaging were performed to diagnose "idiopathic vertigo". By carotico-vertebral Doppler ultrasonography (USG), common carotid artery (CCA) area, intima media thickness; and vertebral artery dimension were measured on the right and left side of the study and control groups.

RESULTS

CCA area values were not different between the study and control groups; and between the right and left sides of the each group. On the left side, intima media thickness and vertebral artery dimension values of the vertigo group were significantly higher than those of the control group. Correlation tests showed that CCA area and intima media thickness values on the right and left side were positively correlated with each other. Moreover, in patients with higher right; or left intima media thickness values, left vertebral artery dimensions decreased. Older age was associated with higher intima media thickness in right and left sides. When CCA values decreased on the right side, VSS-SF values increased; and patients' complaints for vertigo got higher. Linear regression analysis (Backward LR) results also showed that the significant compounding factor on VSS-SF was right CCA area. As right CCA area decreased, VSS-SF increased with more vertigo complaints. Whereas, vertigo complaints and VSS-SF decreased when right CCA increased.

CONCLUSION

We concluded that a decrease in the right CCA were linked with higher VSS-SF scores and increasing vertigo symptoms. Whereas, a decrease in the left CCA area and left crabial blood supply are more important related to the left hemispheric dominance in right-handed people. Moreover, an increase in the intima media thickness was also detected in the vertigo patients and it probably causes a decrease in the central blood flow.

A Prospective Analysis of Lesion-Symptom Relationships in Acute Vestibular and Ocular Motor Stroke

Background: Diagnosing stroke as a cause of acute vertigo, dizziness, or double vision remains a challenge, because symptom characteristics can be variable. The purpose of this study was to prospectively investigate lesion-symptom relationships in patients with acute vestibular or ocular motor stroke.

Methods: Three hundred and fifty one patients with acute and isolated vestibular or ocular motor symptoms of unclear etiology were enrolled in the EMVERT lesion trial. Symptom quality was assessed by the chief complaint (vertigo, dizziness, double vision), symptom intensity by the visual analog scale, functional impairment by EQ-5D-5L, and symptom duration by daily rating. Acute vestibular and ocular motor signs were registered by videooculography. A standardized MRI (DWI-/FLAIR-/T2-/T2^*-/3D-T1-weighted sequences) was recorded within 7 days of symptom onset. MRIs with DWI lesions were further processed for voxel-based lesion-symptom mapping (VLSM).

Results: In 47 patients, MRI depicted an acute unilateral stroke (13.4%). The chief complaints were dizziness (42.5%), vertigo (40.4%) and double vision (17.0%). Lesions in patients with vertigo or dizziness showed a large overlap in the cerebellar hemisphere. VLSM indicated that strokes in the medial cerebellar layers 7b, 8, 9 were associated with vertigo, strokes in the lateral cerebellar layer 8, crus 1, 2 with dizziness, and pontomesencephalic strokes with double vision. Symptom intensity and duration varied largely between patients. Higher symptom intensity and longer duration were associated with medial cerebellar lesions. Hemispheric lesions of the cortex were rare and presented with milder symptoms of shorter duration.

Conclusions: Prospective evaluation of patients with acute vestibular or ocular motor stroke revealed that symptom quality, intensity and duration were not suited to differentiating peripheral from central etiologies. Lesions in the lateral cerebellum, thalamus, or cortex presented with unspecific, mild and transient symptoms prone to being misdiagnosed.

Separating posterior-circulation stroke from vestibular neuritis with quantitative vestibular testing

OBJECTIVE

To separate vestibular neuritis (VN) from posteriorcirculation stroke (PCS) using quantitative tests of canal and otolith function.

METHODS

Video Head-Impulse tests (vHIT) were used to assess all three semicircular canal pairs; vestibulo-ocular reflex (VOR) gain and saccade metrics were examined. Cervical and ocular-Vestibular-Evoked Myogenic Potentials (c- and oVEMP) and Subjective Visual Horizontal (SVH) were used to assess otolith function.

RESULTS

For controls (n = 40), PCS (n = 22), and VN (n = 22), mean horizontal-canal VOR-gains were 0.96 ± 0.1, 0.85 ± 0.3 and 0.40 ± 0.2, refixation-saccade prevalence was 71.9 ± 41, 90.7 ± 57, 209.2 ± 62 per 100 impulses and cumulative-saccade amplitudes were 0.9 ± 0.4°, 2.4 ± 2.2°, 8.0 ± 3.5°. Abnormality-rates for cVEMP, oVEMP and SVH were 38%, 9%, 72% for PCS, and 43%, 50%, 91% for VN. A gain ≤0.68, refixation-saccade prevalence of ≥135% and cumulative-saccade amplitudes ≥5.3° separated VN from PCS with sensitivities of 95.5%, 95.5%, and 81.8%, and specificities of 68.2%, 86.4% and 95.5%. VOR-gain and saccade prevalence when combined, separated VN from PCS with a sensitivity and specificity of 90.9%. Abnormal oVEMP asymmetry-ratios were of low sensitivity (50%) but high specificity (90.9%) for separating VN from PCS.

CONCLUSION

vHIT provided the best separation of VN from PCS. VOR-gain, refixation-saccade prevalence and amplitude were effective discriminators of VN from PCS.

SIGNIFICANCE

vHIT and oVEMP could assist early identification of the aetiology of Acute Vestibular Syndrome in the Emergency Room.

Relation of infarction location and volume to vertigo in vertebrobasilar stroke

OBJECTIVE

Vertigo is a common presentation of vertebrobasilar stroke. Anecdotal reports have shown that vertigo occurs more often in multiple than in single brainstem or cerebellar infarctions. We examined the relation between the location and volume of infarction and vertigo in patients with vertebrobasilar stroke.

METHODS

Consecutive patients with vertebrobasilar stroke were prospectively recruited. The infarction location and volume were assessed in the diffusion-weighted magnetic resonance imaging.

RESULTS

Fifty-nine patients were included, 32 (54.2%) with vertigo and 27 (45.8%) without vertigo. The infarction volume did not correlate with National Institute of Health Stroke Scale (NIHSS) score on admission (Spearman ρ = .077, p = .56) but correlated with modified Rankin Scale (ρ = .37, p = .004) on discharge. In the vertigo group, the proportion of men was lower (53.1% vs. 77.8%, p = .049), fewer patients had focal neurological deficits (65.6% vs. 96.3%, p = .004), patients tended to present later (median [IQR] was 7.5 [4-46] vs. 4 [2-12] hours, p = .052), numerically fewer patients received intravenous thrombolysis (15.6% vs. 37%, p = .06), and the total infarction volume was larger (5.6 vs. 0.42 cm³ , p = .008) than in nonvertigo group. In multivariate logistic regression, infarction location either in the cerebellum or in the dorsal brainstem (odds ratio [OR] 16.97, 95% CI 3.1-92.95, p = .001) and a total infarction volume of >0.48 cm³ (OR 4.4, 95% CI 1.05-18.58, p = .043) were related to vertigo. In another multivariate logistic regression, after adjusting for age, sex, intravenous thrombolysis, serum level of white blood cells, and atrial fibrillation, vertigo independently predicted a total infarction volume of >0.48 cm³ (OR 5.75, 95% CI 1.43-23.08, p = .01).

CONCLUSION

Infarction location in the cerebellum and/or dorsal brainstem is an independent predictor of vertigo. Furthermore, larger infarction volume in these structures is associated with vertigo. A considerable proportion of patients with vascular vertigo present without focal neurological deficits posing a diagnostic challenge. National Institute of Health Stroke Scale is not sensitive for vertebrobasilar stroke.

Differential diagnosis of acute vascular vertigo

PURPOSE OF REVIEW

The current review covers recent advances in vascular vertigo in terms of diagnostic strategies, clinical/laboratory features, pathophysiology, and differential diagnosis.

RECENT FINDINGS

Acute strokes presenting with isolated dizziness/vertigo without other obvious symptoms or signs of central nervous system involvements may be easily mistaken as peripheral vestibulopathy. For correct diagnosis of vascular vertigo, the importance of clinical history (timing and triggers) and targeted bedside examination cannot be overemphasized. In addition to Head Impulse-Nystagmus-Test of Skew, several differential strategies have been advanced by adopting a combination of clinical history, bedside or laboratory examination, and imaging for diagnosis of vascular vertigo. Circumscribed cerebellar and brainstem lesions may cause isolated central vestibular syndromes with characteristic vestibular and ocular motor manifestations. Recognition of these findings would aid in localizing the lesions and understanding the function of each central vestibular structure. Central positional nystagmus (CPN) may mimic benign paroxysmal positional vertigo (BPPV), but additional oculomotor or neurological findings mostly permit differentiation of CPN from BPPV.

SUMMARY

In acute vestibular syndrome, discriminating vascular causes is still challenging especially when other central symptoms and signs are not evident. An integrated approach based on understanding of clinical features, laboratory findings, speculated mechanisms, and limitations of current diagnostic tests will lead to better clinical practice.

Prevalence of Stroke and Hypoperfusion in Patients With Isolated Vertigo and Vascular Risk Factors

Background and Purpose: The aim of this study was to determine the prevalence and associated factors of stroke and hypoperfusion among patients with isolated vertigo and vascular risk factors.

Methods: We studied 157 patients with isolated vertigo who had undergone multimodal magnetic resonance imaging. Magnetic resonance angiography (MRA) was used to measure the diameters of vertebrobasilar arteries and to evaluate morphologic changes to vessels. Measurements obtained included length of the basilar artery and curvature index for the vertebral artery (VA). Perfusion-weighted imaging (PWI) was performed to determine relative cerebral blood flow, relative cerebral blood volume (rCBV), time to peak (TTP), and mean transit time for two mirror regions of interest (ROIs) in each map. Regional hypoperfusion of the cerebellum was considered significant when TTP and mean transit time (MTT) were present in ≥2 adjacent slices.

Results: The prevalence of stroke in patients with isolated vertigo and vascular risk factors was 24.8% (n = 39). Visual assessment revealed cerebellar hypoperfusion in 57.6% (68/118) of non-stroke patients. Multivariate logistic regression indicated that diabetes mellitus (P = 0.049, OR = 2.758), VA stenosis or hypoplasia (P = 0.023, OR = 3.486), and relative TTP of cerebellum (P = 0.002, OR = 3.197) were independent risk factors for stroke and LVA curvature index (P = 0.026, OR = 2.049), VA stenosis and hypoplasia (P = 0.009, OR = 2.977) were independent risk factors for hypoperfusion.

Conclusions: The prevalence of stroke and hypoperfusion is higher in patients with isolated vertigo and vascular risk factors, compared with matched controls. Potential risk factors include diabetes mellitus, VA stenosis or hypoplasia, and enlarged VA curvature index.

Clinical Study on 3 Patients with Infarction of the Vermis/Tonsil in the Cerebellum

BACKGROUND

Infarction of the vermis and the tonsil in the cerebellum presents as truncal and gait ataxia. Acute rotatory vertigo is often present in infarction of the nodulus in the caudal vermis, which is closely associated with the vestibular pathway, but is minor in infarction of the rostral vermis. The rostral vermis receives input from the dorsal spinocerebellar tract (DSCT) which conveys unconsciousness proprioceptive signals from the ipsilateral lower trunk and leg. The present study investigated the characteristics of infarction of the vermis and the tonsil.

PATIENTS AND METHODS

Neuroradiological findings of 3 patients whose lesions were located in the vermis or the tonsil were analyzed.

RESULTS

All lesions were located in the anterior lobe in the rostral vermis, the nodulus in the caudal vermis, or the tonsil. Truncal and gait ataxia were exhibited by 3 patients. Rotatory vertigo was exhibited by 2 patients whose lesions were located in the nodulus and the tonsil, but absent in a patient with infarction of the anterior lobe. Lateropulsion opposite the lesion was apparent in a patient with infarction of the tonsil. Gaze-evoked nystagmus was observed in 2 patients with infarction of the nodulus and the tonsil.

CONCLUSIONS

The tonsil and the nodulus were considered to have a close relationship with the vestibular pathway. Absence of rotatory vertigo indicated impairment of the DSCT. Our data suggested that the cause of truncal and gait ataxia differed between the rostral vermis and the caudal vermis/tonsil.

Central vertigo

PURPOSE OF REVIEW

This review considers recent advances in central vertigo in terms of clinical and laboratory features and pathophysiology.

RECENT FINDINGS

Strokes presenting dizziness-vertigo are more likely to be associated with a misdiagnosis in the emergency setting. The risk of future strokes after discharge is higher in patients diagnosed with peripheral vertigo than in control patients. Strokes and transient ischemic attacks account for one-quarter of acute transient vestibular syndrome. Diagnosis of acute combined central and peripheral vestibulopathy such as anterior inferior cerebellar artery infarction requires additional consideration whenever applying the HINTS (head impulse test, direction-changing gaze-evoked nystagmus, and test of skew). Heat illness and metronidazole have been recognized as new causes of central vestibulopathy. Some new findings have also been added to the clinical and laboratory features of central vertigo.

SUMMARY

Central vertigo is a heterogeneous group of disorders with diverse clinical spectrums. An integrated approach based on understanding of clinical features, laboratory findings, speculated mechanisms, and limitations of current diagnostic tests will lead to better clinical practice.

Central Lesions With Selective Semicircular Canal Involvement Mimicking Bilateral Vestibulopathy

Bilateral vestibulopathy (BVP), which is due to peripheral lesions, may selectively involve certain semicircular canal (SCC). Recent eye movement recordings with search coil and video head impulse test (HIT) have provided insight in central lesions that can cause bilateral and selective SCC deficit mimicking BVP. Since neurological signs or ocular motor deficits maybe subtle or absent, it is critical to recognize central lesions correctly since there is prognostic and treatment implication. Acute floccular lesions cause bilateral horizontal SCC (HC) impairment while leaving vertical SCC function unaffected. Vestibular nuclear lesions affect bilateral HC and posterior SCC (PC) function, but anterior SCC (AC) function is spared. When both eyes are recorded, medial longitudinal fasciculus lesions cause horizontal dysconjugacy in HC function and catch-up saccades, as well as selective deficiency of PC over AC function. Combined peripheral and central lesions may be difficult to distinguish from BVP. Anterior inferior cerebellar artery stroke causes two types of deficits: 1. ipsilateral pan-SCC deficits and contralateral HC deficit and 2. bilateral HC deficit with vertical SCC sparing. Metabolic disorders such as Wernicke encephalopathy characteristically involve HC but not AC or PC function. Gaucher disease causes uniform loss of all SCC function but with minimal horizontal catch-up saccades. Genetic cerebellar ataxias and cerebellar-ataxia neuropathy vestibular areflexia syndrome typically do not spare AC function. While video HIT does not replace the gold-standard, search coil HIT, clinicians are now able to rapidly and accurately identify specific pattern of SCC deficits, which can aid differentiation of central lesions from BVP.

Why acute unilateral vestibular midbrain lesions rarely manifest with rotational vertigo: a clinical and modelling approach to head direction cell function

A retrospective clinical study focused on the frequency of rotational vertigo in 63 patients with acute unilateral midbrain strokes involving the vestibular and ocular motor systems. In contrast to unilateral pontomedullary brainstem lesions, rotational vertigo in midbrain lesions occurred with a low frequency (14%) and transient (< 1 day) course. Swaying vertigo or unspecific dizziness (22%) and postural imbalance (31%) were more frequent. Midbrain strokes with transient rotational vertigo manifested with lesions chiefly in the caudal midbrain tegmentum, while manifestations with swaying, unspecific, or no vertigo chiefly occurred in rostral mesencephalic or meso-diencephalic lesions. We hypothesize that these different manifestations can be explained by the distribution of two separate cell systems based on semicircular canal function: the angular head-velocity cells and the head direction cells, both of which code for head rotation. Animal experiments have shown that angular head-velocity cells are located mainly in the lower brainstem up to the midbrain, whereas the head direction cells are found from the midbrain and thalamic level up to cortical regions. Due to the differences in coding, unilateral dysfunction of the angular velocity cell system should result in the sensation of rotation, while unilateral dysfunction of the head direction cell system should result in dizziness and unsteadiness. We simulated the different manifestations of vestibular dysfunction using a mathematical neural network model of the head direction cell system. This model predicted and confirmed our clinical findings that unilateral caudal and rostral brainstem lesions have different effects on vestibular function.

Acute vestibular syndrome: clinical head impulse test versus video head impulse test

HINTS battery involving head impulse test (HIT), nystagmus, and test of skew is the critical bedside examination to differentiate acute unilateral peripheral vestibulopathy from posterior circulation stroke (PCS) in acute vestibular syndrome (AVS). The highest sensitivity component of the battery has been reported to be the horizontal HIT, whereas skew deviation is defined as the most specific but non-sensitive sign for PCS. Video-oculography-based HIT (vHIT) may have an additional power in making the differentiation. If vHIT is undertaken, then both gain and gain asymmetry should be taken into account as anterior inferior cerebellar artery (AICA) strokes are at risk of being misclassified based on VOR gain alone. Further refinement in video technology, increased operator proficiency and incorporation with saccade analysis will increase the sensitivity of vHIT for PCS diagnosis. For the time being, clinical examination seems adequate in frontline diagnostic evaluation of AVS.