Isolated central vestibular syndrome

The diagnostic value of the ocular tilt reaction plus head tilt subjective visual vertical (±45°) in patients with acute central vascular vertigo

Objectives

To investigate the localization diagnostic value of the ocular tilt reaction (OTR) plus head tilt subjective visual vertical (SVV) in patients with acute central vascular vertigo (ACVV).

Methods

We enrolled 40 patients with acute infarction, 20 with unilateral brainstem infarction (BI) and 20 with unilateral cerebellar infarction (CI). We also included 20 patients with unilateral peripheral vestibular disorders (UPVD) as the control group. The participants completed the OTR and SVV during head tilt (±45°) within 1 week of symptom onset.

Results

In patients with ACVV, including that caused by lateral medullary infarction (100%, 2/2), partial pontine infarction (21%, 3/14), and cerebellum infarction (35%, 7/20), we observed ipsiversive OTR, similar to that seen in UPVD patients (80.0%, 16/20). Some of the patients with medial medullary infarction (50%, 1/2), partial pons infarction (42%, 6/14), midbrain infarction (100%, 2/2), and partial cerebellum infarction (30.0%, 6/20) showed contraversive OTR. The skew deviation (SD) of the BI group with ACVV was significantly greater than that of the UPVD group (6.60 ± 2.70° vs. 1.80 ± 1.30°, Z = −2.50, P = 0.012), such that the mean SD of the patients with a pons infarction was 9.50° and that of patients with medulla infarction was 5.00°. In ACVV patients with no cerebellar damage, the area under the curve of the receiver operating characteristic curve corresponding to the use of SD to predict brainstem damage was 0.92 (95%CI: 0.73–1.00), with a sensitivity of 100% and a specificity of 80% when SD ≥ 3°. We found no statistical difference in SD between the UPVD and CI groups (1.33 ± 0.58° vs. 1.80 ± 1.30°, Z = −0.344, P = 0.73). Compared with the UPVD patients, the ACVV patients with a partial pons infarction (43%, 6/14, χ2 = 13.68, P = 0.002) or medulla infarction (25%, 1/4, χ2 = 4.94, P = 0.103) exhibited signs of the ipsiversive E-effect with the contraversive A-effect, while those with a partial medulla infarction (50%, 2/4), pons infarction (43%, 6/14), or cerebellar infarction (60%, 12/20) exhibited a pathological symmetrical increase in the E-effect.

Conclusions

The evaluation of OTR plus head tilt SVV (±45°) in vertigo patients is helpful for identifying and diagnosing ACVV, especially when SD is ≥ 3° or the E-effect is symmetrically increased.

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.

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.

[Acute vestibular syndrome in emergency departments : Clinical differentiation of peripheral and central vestibulopathy]

INTRODUCTION

The differentiation between central and peripheral vestibular disorders is difficult in some cases, especially during the clinical routine of an emergency department (ED) without otoneurological diagnostic equipment. This study evaluated the frequency of vestibular pseudoneuritis as distinguished from acute peripheral vestibular disorders in patients who were admitted to hospital with the suspicion of vestibular neuropathy (VN).

METHODS

This retrospective study analyzed the results of anamnestic and clinical examinations of 315 patients admitted to the emergency department and the inpatient otoneurological examination results as well as the imaging of morphological alterations. In the ED, the clinical examination by a neurologist and an otorhinolaryngologist resulted in the characteristic signs of peripheral VN but no further evidence of a neurological disorder. Patients without signs of a peripheral vestibular disorder in the otoneurological diagnostics subsequently underwent cerebral magnetic resonance imaging scans (cMRI).

RESULTS

Suspected isolated VN could be confirmed in 69% of the patients; however, in a further 29% of the patients neither the suspected isolated VN nor an ischemic pathology of the central nervous system as a cause of the vertigo could be confirmed. Additional cMRI scans revealed that 2% of patients suffered from an infarction of the mesencephalon, the pons, the medulla oblongata and the cerebellum.

CONCLUSION

In rare cases central cerebral disorders mimic the pattern of a peripheral vestibular disorder. Despite thorough history taking, neurological and otolaryngological clinical examinations, it is not always possible to distinguish central and peripheral vestibular disorders of patients in emergency care suffering from acute vertigo. Video oculography-assisted caloric testing and the video head impulse test are recommended to confirm a peripheral VN. In cases without confirmation of suspected NV in otoneurological diagnostics, infarction of the mesencephalon, brain stem and cerebellum should be excluded by diffusion-weighted cMRI.

Ocular Motor Dysfunction Due to Brainstem Disorders

BACKGROUND

The brainstem contains numerous structures including afferent and efferent fibers that are involved in generation and control of eye movements.

EVIDENCE ACQUISITION

These structures give rise to distinct patterns of abnormal eye movements when damaged. Defining these ocular motor abnormalities allows a topographic diagnosis of a lesion within the brainstem.

RESULTS

Although diverse patterns of impaired eye movements may be observed in lesions of the brainstem, medullary lesions primarily cause various patterns of nystagmus and impaired vestibular eye movements without obvious ophthalmoplegia. By contrast, pontine ophthalmoplegia is characterized by abnormal eye movements in the horizontal plane, while midbrain lesions typically show vertical ophthalmoplegia in addition to pupillary and eyelid abnormalities.

CONCLUSIONS

Recognition of the patterns and characteristics of abnormal eye movements observed in brainstem lesions is important in understanding the roles of each neural structure and circuit in ocular motor control as well as in localizing the offending lesion.

Clinical and laboratory factors related to acute isolated vertigo or dizziness and cerebral infarction

OBJECTIVE

To clarify the relationship of clinical factors with isolated vertigo or dizziness of cerebrovascular origin.

METHODS

Clinical data of patients admitted in East Hospital from Jan. 2015 to Apr. 2016, whose complaint were acute vertigo or dizziness were retrospectively collected. All patients arrived at the emergency department within 24 hr of symptom onset, had no acute ischemic lesion first CT and NIHSS score of 0. Patients were divided into cerebral infarction group and noncerebral infarction group according to subsequent cerebral imaging results and clinical and laboratory factors related to cerebral infarction were analyzed.

RESULT

51.6% of patients were female (n = 141). 46 patients (16.8%) were diagnosed with acute cerebral infarction. Baseline demographic data of the two groups was not significantly different. Univariate analysis found that history of smoking (p = 0.009), headache (p = 0.028), unsteadiness (p = 0.009), neuron specific enolase (p = 0.001), and vertebral artery abnormalities found on imaging (p = 0.009) were the significant difference between two groups. Increased neuron specific enolase (p = 0.005) and an abnormal vertebral artery (p = 0.044) were significant on multivariate analysis.

CONCLUSIONS

16.8% of acute isolated vertigo or dizziness presentations were diagnosed with acute cerebral infarction. Increased serum neuron specific enolase and vertebral artery abnormalities were the strongest indicators of acute cerebral infarction.

Diffusion-Weighted Zonal Oblique Multislice-EPI Enhances the Detection of Small Lesions with Diffusion Restriction in the Brain Stem and Hippocampus: A Clinical Report of Selected Cases

Diffusion restriction is the morphologic hallmark of acute ischemic infarcts and excitotoxic brain injury in various cerebral pathologies. Diffusion restriction is visible as hyperintensity on DWI and as hypointensity on ADC maps. Due to the vicinity of multiple anatomic structures in the brain stem and hippocampus, very small lesions with diffusion restriction may result in severe clinical symptomatology, but these small lesions easily go undetected on standard cerebral DWI due to insufficient spatial resolution, T2* blurring, and image artifacts caused by susceptibility-related image distortions. Diffusion-weighted zonal oblique multislice-EPI with reduced FOV acquisition permits a considerable increase in spatial resolution and enhances the visualization of very small pathologic lesions in the brain stem and hippocampus. Improved performance in the depiction of different pathologic lesions with diffusion restriction in the brain stem and hippocampus using this sequence compared with standard DWI in selected cases is presented.

Clinical and video head impulse test in the diagnosis of posterior circulation stroke presenting as acute vestibular syndrome in the emergency department

INTRODUCTION

Head impulse test (HIT) is the critical bedside examination which differentiates vestibular neuritis (VN) from posterior circulation stroke (PCS) in acute vestibular syndrome (AVS). Video-oculography based HIT (vHIT) may have aadditional strength in making the differentiation.

METHODS

Patients admitted to the emergency department of a tertiary-care medical center with AVS were studied. An emergency specialist and a neurologist performed HIT. vHIT was conducted by an neuro-otology research fellow.

RESULTS

Forty patients 26 male, 14 female with a mean age of 49 years were included in the analyses. Final diagnoses were VN in 24 and PCS in 16 patients.In the VN group, clinical HIT was assessed as abnormal in 19(80%) cases by the emergency specialist and in 20(83%) by the neurologist. In all PCS patients, HIT was recorded as normal both by the emergency specialist and the neurologist (100%).On vHIT, patients with VN had significantly low gain values for both the ipsilesional and contralesional sides when compared with the healthy controls, with significantly lower figures for the ipsilesional side (p < 0.001). All patients in this group had normal DWI-MRI.PCS patients had bilaterally low gain (p < 0.05) on vHIT. However, gain asymmetry was not significant. Subgroup analyses according to presence of brainstem involvement revealed bilateral low gain (p < 0.05) in patients with brainstem infarction (anterior inferior cerebellar artery-posterior inferior cerebellar artery stroke, AICA-PICA stroke) whereas patients with pure cerebellar infarction (posterior inferior cerebellar artery-superior cerebellar artery stroke, PICA-SCA stroke) had gain values similar to healthy controls.With a gain cut-off ≤0.75 and gain asymmetry cut-off ≥17%, as determined by ROC analysis, 100% of PCS patients and 80% of VN patients were correctly diagnosed.

CONCLUSIONS

Clinical HIT, either performed by an emergency specialist or neurologist is equivalent to vHIT gain and gain asymmetry analysis as conducted by neuro-otologist in the diagnosis of PCS, albeit mislabeling about 20% of VN patients. vHIT does not appear to yield additional diagnostic information. These findings indicate the strength of clinical HIT. Pure gain-based vHIT analysis seems limited and needs to be incorporated with saccade analysis.

Analysis of Risk Factors in Patients With Peripheral Vertigo or Central Vertigo

INTRODUCTION

This study was aimed to determine risk factors for central vertigo (CV) in patients with isolated vertigo accompanied by hearing loss or not.

PATIENTS AND METHODS

Patients with CV or peripheral vertigo (PV) who were admitted to our hospital between January 2014 and July 2016 were retrospectively reviewed. All patients underwent thorough physical examination with detailed medical histories recorded, including smoking, hypertension, diabetes, cardiovascular disease, and stroke history. Logistic regression estimated odds ratio (OR) of the risk factors.

RESULTS

Eighty-seven patients were enrolled into the study, including 41 cases of CV and 46 cases of PV. There was significant difference in sex, age above 60, hypertension, diabetes, smoking, and stroke history between the 2 groups. The patients without any risk factors did not have CV. The risk for CV in the patients with ≥3 risk factors was greater (OR, 11.43; 95% confidence interval, 3.27-39.93; P<0.001) than the patients with 1 risk factor. The risk for CV in the patients with 2 risk factors was similar (OR, 0.833; 95% confidence interval, 0.17-4.28; P=0.825) to the patients with 1 risk factor.

CONCLUSION

The patients with isolated vertigo (accompanied by hearing loss or not) and 3 or more risk factors are at higher risk for CV. They should have a comprehensive neurological examination and be closely followed up.

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.

Effects of Head Position on Perception of Gravity in Vestibular Neuritis and Lateral Medullary Infarction

Objective

Internal representation of gravity can be quantified by measuring the subjective visual vertical (SVV). Modulation of verticality perception during head tilts may be perturbed in vestibular disorders causing SVV tilts in the upright head position. This study aimed to determine the influence of head tilts on the estimation of SVV in acute vestibular disorders.

Methods

We measured the SVV in 37 patients with acute vestibular symptoms due to unilateral vestibular neuritis (VN) (n = 28) and lateral medullary infarction (LMI) (n = 9). Measurements of the SVV were performed under head upright, head tilt 30° and 60° in each direction. Seventeen normal subjects served as the control.

Results

In controls, head tilt of 30° produced a contraversive shift of the SVV (the E-effect), and head tilt of 60° generated an ipsiversive shift (the A-effect). Patients with VN showed only the A-effect irrespective of the direction and amplitude of head tilt. Patients with LMI could estimate earth verticality accurately during head tilts. Patients with VN during the recovery phase showed the patterns of SVV modulation similar to those observed in the controls either with head upright or tilted.

Conclusion

Given the absence of the E-effect in acute VN, the peripheral otolithic inputs appear to be essential in the perception of earth vertical during small static head tilts.

Recent Advances in Cerebellar Ischemic Stroke Syndromes Causing Vertigo and Hearing Loss

Cerebellar ischemic stroke is one of the common causes of vascular vertigo. It usually accompanies other neurological symptoms or signs, but a small infarct in the cerebellum can present with vertigo without other localizing symptoms. Approximately 11 % of the patients with isolated cerebellar infarction simulated acute peripheral vestibulopathy, and most patients had an infarct in the territory of the medial branch of the posterior inferior cerebellar artery (PICA). A head impulse test can differentiate acute isolated vertigo associated with PICA territory cerebellar infarction from more benign disorders involving the inner ear. Acute hearing loss (AHL) of a vascular cause is mostly associated with cerebellar infarction in the territory of the anterior inferior cerebellar artery (AICA), but PICA territory cerebellar infarction rarely causes AHL. To date, at least eight subgroups of AICA territory infarction have been identified according to the pattern of neurotological presentations, among which the most common pattern of audiovestibular dysfunction is the combined loss of auditory and vestibular functions. Sometimes acute isolated audiovestibular loss can be the initial symptom of impending posterior circulation ischemic stroke (particularly within the territory of the AICA). Audiovestibular loss from cerebellar infarction has a good long-term outcome than previously thought. Approximately half of patients with superior cerebellar artery territory (SCA) cerebellar infarction experienced true vertigo, suggesting that the vertigo and nystagmus in the SCA territory cerebellar infarctions are more common than previously thought. In this article, recent findings on clinical features of vertigo and hearing loss from cerebellar ischemic stroke syndrome are summarized.

Cerebellar re-encoding of self-generated head movements

Head movements are primarily sensed in a reference frame tied to the head, yet they are used to calculate self-orientation relative to the world. This requires to re-encode head kinematic signals into a reference frame anchored to earth-centered landmarks such as gravity, through computations whose neuronal substrate remains to be determined. Here, we studied the encoding of self-generated head movements in the rat caudal cerebellar vermis, an area essential for graviceptive functions. We found that, contrarily to peripheral vestibular inputs, most Purkinje cells exhibited a mixed sensitivity to head rotational and gravitational information and were differentially modulated by active and passive movements. In a subpopulation of cells, this mixed sensitivity underlay a tuning to rotations about an axis defined relative to gravity. Therefore, we show that the caudal vermis hosts a re-encoded, gravitationally polarized representation of self-generated head kinematics in freely moving rats.

Eye movement and vestibular dysfunction in mitochondrial A3243G mutation

Studying eye movements and vestibular function would provide insights into brain networks that are vulnerable in mitochondrial disorders. We sought eye movement and vestibular abnormalities in three Korean patients with a mitochondrial A3243G point mutation. The patients suffered from vertigo and imbalance during the stroke-like and seizure episodes from lesions involving the posterior cerebral cortex, which were accompanied by bilateral saccadic hypermetria and horizontal gaze-evoked nystagmus. Furthermore, two patients showed bilateral impairments of the vestibulo-ocular reflex during head impulses for the horizontal and posterior canals on both sides in the absence of caloric paresis. Cerebellar atrophy was prominent on MRIs in two patients and was less marked in the other patient. These findings imply that the cerebellum is susceptible to neuronal energy deficiency due to mitochondrial A3243G point mutation.

Ischemic syndromes causing dizziness and vertigo

Dizziness/vertigo and imbalance are the most common symptoms of vertebrobasilar ischemia. Even though dizziness/vertigo usually accompanies other neurologic symptoms and signs in cerebrovascular disorders, a diagnosis of isolated vascular vertigo is increasing markedly by virtue of recent developments in clinical neurotology and neuroimaging. It is important to differentiate isolated vertigo of a vascular cause from more benign disorders involving the inner ear, since therapeutic strategies and prognosis differ between these two conditions. Over the last decade, we have achieved a marked development in the understanding and diagnosis of vascular dizziness/vertigo. Introduction of diffusion-weighted magnetic resonance imaging (MRI) has greatly enhanced detection of infarctions in patients with vascular dizziness/vertigo, especially in the posterior-circulation territories. However, well-organized bedside neurotologic evaluation is even more sensitive than MRI in detecting acute infarction as a cause of spontaneous prolonged vertigo. Furthermore, detailed evaluation of strategic infarctions has elucidated the function of various vestibular structures of the brainstem and cerebellum. In contrast, diagnosis of isolated labyrinthine infarction still remains a challenge. This diagnostic difficulty also applies to isolated transient dizziness/vertigo of vascular origin. Regarding the common nonlacunar mechanisms in the acute vestibular syndrome from small infarctions, individual strategies may be indicated to prevent recurrences of stroke in patients with vascular vertigo.

Approach to dizziness in the emergency department

Acute dizziness/vertigo is among the most common causes for visiting the emergency department. The traditional approach to dizziness starts with categorizing dizziness into four types: vertigo, presyncope, disequilibrium, and nonspecific dizziness. However, a recently proposed approach begins with classifying dizziness/vertigo as acute prolonged spontaneous dizziness/vertigo, recurrent spontaneous dizziness/vertigo, recurrent positional vertigo, or chronic persistent dizziness and imbalance. Vestibular neuritis and stroke are key disorders causing acute prolonged spontaneous dizziness/vertigo, but the diagnosis of isolated vascular vertigo has increased by virtue of developments in clinical neurotology and neuroimaging. However, a well-organized bedside examination appears more sensitive than brain imaging in diagnosing strokes presenting with acute dizziness/vertigo. A detailed history is vital to diagnose recurrent spontaneous dizziness/vertigo since confirmatory diagnostic tests are usually unavailable. Isolated positional vertigo is usually caused by benign paroxysmal positional vertigo, which can be treated at the bedside. In recent years, marked progress has occurred in the evaluation/management of acute dizziness/vertigo. However, even with developments in imaging technology, the diagnosis of acute dizziness/vertigo largely relies on bedside examination.