Central compensation of deviated subjective visual vertical in Wallenberg's syndrome

Evaluation of subjective visual vertical and horizontal in patients with acoustic neuroma based on virtual reality

Objective

To investigate potential differences in absolute deviation values of subjective visual vertical and horizontal between unilateral acoustic neuroma patients and healthy young adults under varying degrees of static head tilt, as well as the impact of proprioception on these values, with the aim of determining the effect of acoustic neuroma on gravity sensory pathway function in patients.

Methods

We recruited 22 patients diagnosed with unilateral acoustic neuroma and 25 healthy young adults and employed virtual reality technology to assess the absolute deviation values of subjective visual vertical (SVV) and subjective visual horizontal (SVH) under eight different static tilted head positions (Head centered (0° tilt), PdP, Head tilt 15°, 30°, 45° to the left and right), then compare and analyze intergroup differences.

Results

In the Head-centered position, both SVV and SVH absolute deviated values were significantly higher in the AN group compared to healthy young adults. The AN group exhibited significantly higher absolute deviation values of SVV compared to the healthy group when tilting their head 30° left and right. Additionally, when tilting their heads to the right at 15° and 45° the AN group showed significant increases in SVH absolute deviated values compared to healthy adults. The SVV and SVH absolute deviation values of LAN and SAN groups did not reach statistical significance. The results of the SVV test for PDP position did not show any significant differences among all groups. However, the SVH test revealed that the absolute deviation values of the LAN group was significantly higher than that of healthy individuals.

Conclusion

Our study shows that the gravity sensing function of patients with unilateral acoustic neuroma is affected to different degrees, however, the degree of gravity sensing function damage of patients has little relationship with tumor size. When acoustic neuroma is larger than 2 cm, the effect of proprioception on patients' SVH outcome is noteworthy. So, we should pay attention to the postoperative follow-up of patients with acoustic neuroma and the evaluation of vestibular rehabilitation effect. Meanwhile, for patients opting for conservative treatment, it is imperative to monitor the dynamic changes in vestibular function and seize timely opportunities for intervention.

Determinants of functioning and health-related quality of life after vestibular stroke

Background

Stroke accounts for 5–10% of all presentations with acute vertigo and dizziness. The objective of the current study was to examine determinants of long-term functioning and health-related quality of life (HRQoL) in a patient cohort with vestibular stroke.

Methods

Thirty-six patients (mean age: 66.1 years, 39% female) with an MRI-proven vestibular stroke were followed prospectively (mean time: 30.2 months) in the context of the EMVERT (EMergency VERTigo) cohort study at the Ludwig-Maximilians Universität, Munich. The following scores were obtained once in the acute stage (<24 h of symptom onset) and once during long-term follow-up (preferably >1 year after stroke): European Quality of Life Scale-five dimensions-five levels questionnaire (EQ-5D-5L) and Visual Analog Scale (EQ-VAS) for HRQoL, Dizziness Handicap Inventory (DHI) for symptom severity, and modified Rankin Scale (mRS) for general functioning and disability. Anxiety state and trait were evaluated by STAI-S/STAI-T, and depression was evaluated by the Patient Health Questionnaire-9 (PHQ-9). Voxel-based lesion mapping was applied in normalized MRIs to analyze stroke volume and localization. Multiple linear regression models were calculated to determine predictors of functional outcome (DHI, EQ-VAS at follow-up).

Results

Mean DHI scores improved significantly from 45.0 in the acute stage to 18.1 at follow-up (p < 0.001), and mean mRS improved from 2.1 to 1.1 (p < 0.001). Mean HRQoL (EQ-5D-5L index/EQ-VAS) changed from 0.69/58.8 to 0.83/65.2 (p = 0.01/p = 0.11). Multiple linear regression models identified higher scores of STAI-T and DHI at the time of acute vestibular stroke and larger stroke volume as significant predictors for higher DHI at follow-up assessment. The effect of STAI-T was additionally enhanced in women. There was a significant effect of patient age on EQ-VAS, but not DHI during follow-up.

Conclusion

The average functional outcome of strokes with the chief complaint of vertigo and dizziness is favorable. The most relevant predictors for individual outcomes are the personal anxiety trait (especially in combination with the female sex), the initial symptom intensity, and lesion volume. These factors should be considered for therapeutic decisions both in the acute stage of stroke and during subsequent rehabilitation.

Comparison of Clinical Balance and Visual Dependence Tests in Patients With Chronic Dizziness With and Without Persistent Postural-Perceptual Dizziness: A Cross-Sectional Study

Background

The diagnosis of persistent postural-perceptual dizziness (PPPD) is primarily based on medical history taking. Research on the value of clinical balance and visual dependence tests in identifying PPPD is scarce.

Objectives

(1) to contrast clinical balance and visual dependence tests between PPPD patients, dizzy non-PPPD patients, and healthy persons; and (2) to evaluate whether these clinical tests can help to identify PPPD in patients with chronic dizziness.

Methods

Consecutive patients with chronic dizziness (38 PPPD and 21 non-PPPD) and 69 healthy persons underwent Static Balance tests, the Timed Up and Go test, the Tandem Gait test, and the Functional Gait Assessment (FGA). Visual dependence tests included the Visual Vertigo Analog Scale (VVAS), the Rod-and-Disc test (RDT), and postural sway while facing rotating dots. Groups were compared using ANOVA with post-hoc Tukey, or independent samples t-tests. The value of the clinical tests for PPPD identification was evaluated through logistic regression and Partial Least Squares Discriminant (PLS-DA) analyses.

Results

PPPD patients had significantly higher VVAS scores than dizzy non-PPPD patients (p = 0.006). Facing rotating dots, PPPD and dizzy non-PPPD patients had increased postural sway compared to healthy persons (PPPD vs. healthy: center of pressure (COP) velocity p &lt; 0.001, and COP area p &lt; 0.001; but non-PPPD vs. healthy: COP velocity p = 0.116 and COP area p = 0.207). PPPD patients had no significantly increased postural sway compared to dizzy non-PPPD patients. PPPD and dizzy non-PPPD patients also scored significantly worse on balance tests compared to healthy persons (PPPD vs. healthy: for all balance tests p &lt; 0.001; non-PPPD vs. healthy: FGA p &lt; 0.001, for all other tests p &lt; 0.05). Differences were insignificant in balance scores between PPPD and dizzy non-PPPD patients, or in RDT scores between the three study groups. In patients with chronic dizziness, a higher VVAS score was most associated with PPPD [odds ratio 1.04; 95% CI (1.01; 1.07); p = 0.010]. The cross-validated (CV) PLS-DA model with all clinical tests included, had fair discriminative ability (CVerror = 47%).

Conclusion

PPPD patients were more visually dependent, but did not have worse postural balance compared to dizzy non-PPPD patients. Elevated VVAS scores characterized PPPD most in patients with chronic dizziness.

Lateropulsion Prevalence after Stroke: A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVES

Lateropulsion is a deficit of active body orientation with respect to gravity in the frontal plane, mostly observed after a stroke. It magnifies mobility limitations and so represents an emerging target in rehabilitation. Efforts to design specific interventional studies require some basic knowledge of epidemiology, which is insufficient today because many studies focused on a few severe forms in individuals called pushers. The objectives of this study were to bridge this gap.

METHODS

We systematically searched MEDLINE, EMBASE, CINAHL, and Cochrane Clinical Trials up to 31 May 2021 for original research reporting a prevalence or incidence of post-stroke lateropulsion. We followed MOOSE and PRISMA guidelines. Eligibility for inclusion, data extraction, and study quality (Joanna Briggs Institute guidelines) were evaluated by two reviewers who used a standardized protocol: PROSPERO (CRD42020175037). A random-effects meta-analysis was used to obtain the pooled prevalence, whose heterogeneity was investigated by subgroup analysis (stroke locations and post-stroke phases) and meta-regression.

RESULTS

We identified 22 studies (5125 individuals; mean age 68.5 years; 42.6% female; assessed 24 days, on average, after stroke), most published after 2000. The studies' quality was adequate, with only 8 (36.4%) showing risk of bias. The pooled lateropulsion prevalence was 55.1% (95% confidence interval [CI] [35.9-74.2]) and was consistent across assessment tools. After supratentorial stroke, lateropulsion prevalence was 41% (95%CI [33.5-48.5]), and only 12.5% (95%CI [9.2-15.9]) in individuals with severe lateropulsion, called pushers. Meta-regression did not reveal any effect of age, sex, geographic region, publication year, or study quality. Lateropulsion prevalence progressively decreased from 52.8% (95%CI [40.7-65]) in the acute phase to 37% (95%CI [26.3-47.7]) in the early subacute phase and 22.8% (95%CI [0-46.3]) in the late subacute phase. The ratio of right- to left-hemispheric stroke with lateropulsion increased as a function of time: 1.7 in the acute phase to 7.7 in the late subacute phase. After infratentorial stroke, lateropulsion prevalence was very high, reaching 83.2% (95%CI [63.9-100.3]).

CONCLUSIONS

Post-stroke lateropulsion prevalence is high, which appeals for its systematic detection to guide early interventions. Uprightness is predominantly controlled from the right hemisphere.

Head Roll-Tilt Subjective Visual Vertical Test in the Diagnosis of Persistent Postural-Perceptual Dizziness

OBJECTIVE

To examine the validity of head roll-tilt subjective visual vertical (HT-SVV) in diagnosing persistent postural-perceptual dizziness (PPPD).

STUDY DESIGN

Retrospective review.

SETTING

Tertiary referral center.

PATIENTS

Sixty-one patients with PPPD, 10 with unilateral vestibular hypofunction (UVH), and 11 with psychogenic dizziness (PD), showing chronic vestibular symptoms for >3 months.

INTERVENTIONS

Head-tilt perception gain (HTPG, i.e., mean perceptual gain [perceived/actual tilt angle]) during right or left head tilt of approximately 30° (HT-SVV) and conventional head-upright SVV (UP-SVV) were measured. Bithermal caloric testing, cervical and ocular vestibular-evoked myogenic potentials (cVEMP and oVEMP), and posturography were conducted.

MAIN OUTCOME MEASURES

Multiple comparisons were performed for the HT-SVV and other vestibular tests among the disease groups. A receiver operating characteristic curve was created to predict PPPD using HTPG.

RESULTS

HTPG was significantly greater in the PPPD group than in the UVH and PD groups. There were no significant differences in UP-SVV, cVEMP, oVEMP, and posturography (foam ratio and Romberg ratio on foam) among the disease groups, while the UVH group had the highest canal paresis compared to the other two groups. The area under the curve of the receiver operating characteristic curve for predicting PPPD was 0.764, and the HTPG value of 1.202 had a specificity of 95.2% for diagnosing PPPD.

CONCLUSIONS

While conventional vestibular tests including UP-SVV, VEMPs, and posturography did not show abnormalities in PPPD, high HTPG in the HT-SVV test, an excessive perception of head tilt, can be a specific marker for discriminating PPPD from other chronic vestibular diseases.

Vestibular compensation of otolith graviceptive dysfunction in stroke patients

BACKGROUND AND PURPOSE

A sensitive and frequent clinical sign of a vestibular tone imbalance is the tilt of the perceived subjective visual vertical (SVV). There are no data yet focusing on lesion location at the cortical level as a factor for predicting compensation from the tilt of the SVV.

METHODS

With modern voxelwise lesion behavior mapping analysis, the present study determines whether lesion location in 23 right-hemispheric cortical stroke patients with an otolith dysfunction could predict the compensation of a vestibular tone imbalance in the chronic stage.

RESULTS

Our statistical anatomical lesion analysis revealed that lesions of the posterior insular cortex are involved in vestibular otolith compensation.

CONCLUSION

The insular cortex appears to be a critical anatomical region for predicting a tilt of the SVV as a chronic disorder in stroke patients.

Subjective visual vertical imprecision during lateral head tilt in patients with chronic dizziness

Most prior studies of the subjective visual vertical (SVV) focus on inaccuracy of subjects' SVV responses with the head in an upright position. Here we investigated SVV imprecision during lateral head tilt in patients with chronic dizziness compared to healthy controls. Forty-five dizzy patients and 45 healthy controls underwent SVV testing wearing virtual reality (VR) goggles, sitting upright (0°) and during head tilt in the roll plane (± 30°). Ten trials were completed in each of three static head positions. The SVV inaccuracy and SVV imprecision were analyzed and compared between groups, along with systematic errors during head tilt, i.e., A-effect and E-effect (E-effect is a typical SVV response during head tilts of ± 30°). The SVV imprecision was found to be affected by head position (upright/right head tilt/left head tilt, p < 0.001) and underlying dizziness (dizzy patients/healthy controls, p = 0.005). The SVV imprecision during left head tilt was greater in dizzy patients compared to healthy controls (p = 0.04). With right head tilt, there was a trend towards greater SVV imprecision in dizzy patients (p = 0.08). Dizzy patients were more likely to have bilateral (6.7%) or unilateral (22.2%) A-effect during lateral head tilt than healthy controls (bilateral (0%) or unilateral (6.7%) A-effect, p < 0.01). Greater SVV imprecision in chronically dizzy patients during head tilts may be attributable to increased noise of vestibular sensory afferents or disturbances of multisensory integration. Our findings suggest that SVV imprecision may be a useful clinical parameter of underlying dizziness measurable with bedside SVV testing in VR.

[Update on diagnosis and therapy in frequent vestibular and balance disorders]

The 8 most frequent vestibular disorders account for more than 70% of all presentations of vertigo, dizziness, and imbalance. In acute (and mostly non-repetitive) vestibular disorders acute unilateral vestibulopathy and vestibular stroke are most important, in episodic vestibulopathies benign paroxysmal positional vertigo (BPPV), Menière's disease and vestibular migraine, and in chronic vestibular disorders bilateral vestibulopathy/presbyvestibulopathy, functional dizziness and cerebellar dizziness. In the last decade, internationally consented diagnostic criteria and nomenclature were established for the most frequent vestibular disorders, which can be easily applied in clinical practice. The diagnostic guidelines are based on history taking (including onset, duration, course, triggers, accomanying symptoms), clinical examination, and only a few apparative tests (by videooculography and audiometry) for securing the diagnosis. Treatment of vestibular disorders includes physical training (repositioning maneuvers, multimodal balance training) and pharmacological approaches (e.g., corticosteroids, antiepileptics, antidepressants, potassium-canal-blockers, drugs enhancing neuroplasticity). For most drugs, high-level evidence from prospective controlled trials is lacking. In clinical practice, the most frequent vestibular disorders can be treated effectively, thus avoiding chronicity and secondary comorbidity (by immobility, falls or psychiatric disorders such as anxiety or depression).

Test-retest reliability of subjective visual vertical measurements with lateral head tilt in virtual reality goggles

Objective:

The objective is to investigate the test-retest reliability of subjective visual vertical (SVV) in the upright position and with lateral head tilts through a computerized SVV measuring system using virtual reality (VR) goggles.

Materials and Methods:

Thirty healthy controls underwent SVV test in upright position, with the head tilted to the right 30°, and with the head tilted to the left 30°. Subjects wore SVV VR goggles, which contained a gyroscope for monitoring the angle of head tilt. Each subject completed 10 adjustments in each head position. The mean value of SVV deviations and SVV imprecision (the intra-individual variability of SVV deviations from the 10 adjustments) were recorded and compared across different head positions. The participants then repeated the same SVV protocol at least 1 week later. The test-retest reliability of SVV deviation and SVV imprecision were analyzed.

Results:

The SVV deviation (mean ± standard deviation) was 0.22° ± 1.56° in upright position, −9.64° ± 5.91° in right head tilt, and 7.20° ± 6.36° in left head tilt. The test-retest reliability of SVV deviation was excellent in upright position (intra-class correlation coefficient [ICC] = 0.77, P < 0.001), right head tilt (ICC = 0.83, P < 0.001) and left head tilt (ICC = 0.84, P < 0.001). The SVV values from the 10 adjustments made during right and left head tilts were less precise than when measured at upright (P < 0.001). The test-retest reliability of SVV imprecision was poor at upright (ICC = 0.21, P = 0.26) but fair-to-good in right head tilt (ICC = 0.72, P < 0.001) and left head tilt (ICC = 0.44, P = 0.04).

Conclusion:

The test-retest reliability of SVV deviation during lateral head tilts via VR goggles is excellent, which supports further research into the diagnostic value of head-tilt SVV in various vestibular disorders. In addition, the degree of SVV imprecision during head tilt has fair-to-good test-retest reliability, which suggests SVV imprecision may have clinical applicability.

The Bucket Test Improves Detection of Stroke in Patients With Acute Dizziness

BACKGROUND

It is challenging to detect posterior circulation strokes in patients presenting to the emergency department (ED) with acute dizziness. The current approach uses a combinatorial head-impulse, nystagmus, and test-of-skew method and is sensitive enough to differentiate central causes from peripheral ones. However, it is difficult to perform and underused. Further, magnetic resonance imaging (MRI) of the brain is not always available and can have low sensitivity for detecting posterior circulation strokes.

OBJECTIVES

We evaluated the feasibility and utility of the bucket test (BT), which measures the difference between patient's subjective perception of the visual vertical and the true vertical, as a screening tool for stroke in patients presenting to the ED with acute dizziness.

METHODS

In this work, we prospectively enrolled 81 patients that presented to our academic medical center ED with dizziness as their chief complaint. The BT was performed 3 times for every patient.

RESULTS

Seventy-one patients met the study criteria and were included in the analysis. Ten patients were excluded because of a history of drug-seeking behavior. There were no reported difficulties performing the BT. Six patients (8%) were diagnosed with ischemic stroke on MRI and 1 additional patient was diagnosed with transient ischemic attack and found to have a stroke on subsequent MRI. All 7 patients with dizziness attributed to cerebrovascular etiology had an abnormal BT, resulting in a sensitivity of 100% (95% confidence interval [CI] 59-100%). The specificity of the BT was 38% (95% CI 24-52%). The positive predictive value of the BT for detecting stroke was 18% (95% CI 15-21%).

CONCLUSIONS

The BT is an easy, cheap, safe, and quick test that is feasible and sensitive to screen acutely dizzy patients for stroke in the ED.

[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.

Global multisensory reorganization after vestibular brain stem stroke

OBJECTIVE

Patients with acute central vestibular syndrome suffer from vertigo, spontaneous nystagmus, postural instability with lateral falls, and tilts of visual vertical. Usually, these symptoms compensate within months. The mechanisms of compensation in vestibular infarcts are yet unclear. This study focused on structural changes in gray and white matter volume that accompany clinical compensation.

METHODS

We studied patients with acute unilateral brain stem infarcts prospectively over 6 months. Structural changes were compared between the acute phase and follow-up with a group of healthy controls using voxel-based morphometry.

RESULTS

Restitution of vestibular function following brain stem infarcts was accompanied by downstream structural changes in multisensory cortical areas. The changes depended on the location of the infarct along the vestibular pathways in patients with pathological tilts of the SVV and on the quality of the vestibular percept (rotatory vs graviceptive) in patients with pontomedullary infarcts. Patients with pontomedullary infarcts with vertigo or spontaneous nystagmus showed volumetric increases in vestibular parietal opercular multisensory and (retro-) insular areas with right-sided preference. Compensation of graviceptive deficits was accompanied by adaptive changes in multiple multisensory vestibular areas in both hemispheres in lower brain stem infarcts and by additional changes in the motor system in upper brain stem infarcts.

INTERPRETATION

This study demonstrates multisensory neuroplasticity in both hemispheres along with the clinical compensation of vestibular deficits following unilateral brain stem infarcts. The data further solidify the concept of a right-hemispheric specialization for core vestibular processing. The identification of cortical structures involved in central compensation could serve as a platform to launch novel rehabilitative treatments such as transcranial stimulations.

Perception of Verticality and Vestibular Disorders of Balance and Falls

Objective: To review current knowledge of the perception of verticality, its normal function and disorders. This is based on an integrative graviceptive input from the vertical semicircular canals and the otolith organs.

Methods: The special focus is on human psychophysics, neurophysiological and imaging data on the adjustments of subjective visual vertical (SVV) and the subjective postural vertical. Furthermore, examples of mathematical modeling of specific vestibular cell functions for orientation in space in rodents and in patients are briefly presented.

Results: Pathological tilts of the SVV in the roll plane are most sensitive and frequent clinical vestibular signs of unilateral lesions extending from the labyrinths via the brainstem and thalamus to the parieto-insular vestibular cortex. Due to crossings of ascending graviceptive fibers, peripheral vestibular and pontomedullary lesions cause ipsilateral tilts of the SVV; ponto-mesencephalic lesions cause contralateral tilts. In contrast, SVV tilts, which are measured in unilateral vestibular lesions at thalamic and cortical levels, have two different characteristic features: (i) they may be ipsi- or contralateral, and (ii) they are smaller than those found in lower brainstem or peripheral lesions. Motor signs such as head tilt and body lateropulsion, components of ocular tilt reaction, are typical for vestibular lesions of the peripheral vestibular organ and the pontomedullary brainstem (vestibular nucleus). They are less frequent in midbrain lesions (interstitial nucleus of Cajal) and rare in cortical lesions. Isolated body lateropulsion is chiefly found in caudal lateral medullary brainstem lesions. Vestibular function in the roll plane and its disorders can be mathematically modeled by an attractor model of angular head velocity cell and head direction cell function. Disorders manifesting with misperception of the body vertical are the pusher syndrome, the progressive supranuclear palsy, or the normal pressure hydrocephalus; they may affect roll and/or pitch plane.

Conclusion: Clinical determinations of the SVV are easy and reliable. They indicate acute unilateral vestibular dysfunctions, the causative lesion of which extends from labyrinth to cortex. They allow precise topographical diagnosis of side and level in unilateral brainstem or peripheral vestibular disorders. SVV tilts may coincide with or differ from the perception of body vertical, e.g., in isolated body lateropulsion.

Neuronal network-based mathematical modeling of perceived verticality in acute unilateral vestibular lesions: from nerve to thalamus and cortex

Acute unilateral lesions of vestibular graviceptive pathways from the otolith organs and semicircular canals via vestibular nuclei and the thalamus to the parieto-insular vestibular cortex regularly cause deviations of perceived verticality in the frontal roll plane. These tilts are ipsilateral in peripheral and in ponto-medullary lesions and contralateral in ponto-mesencephalic lesions. Unilateral lesions of the vestibular thalamus or cortex cause smaller tilts of the perceived vertical, which may be either ipsilateral or contralateral. Using a neural network model, we previously explained why unilateral vestibular midbrain lesions rarely manifest with rotational vertigo. We here extend this approach, focussing on the direction-specific deviations of perceived verticality in the roll plane caused by acute unilateral vestibular lesions from the labyrinth to the cortex. Traditionally, the effect of unilateral peripheral lesions on perceived verticality has been attributed to a lesion-based bias of the otolith system. We here suggest, on the basis of a comparison of model simulations with patient data, that perceived visual tilt after peripheral lesions is caused by the effect of a torsional semicircular canal bias on the central gravity estimator. We further argue that the change of gravity coding from a peripheral/brainstem vectorial representation in otolith coordinates to a distributed population coding at thalamic and cortical levels can explain why unilateral thalamic and cortical lesions have a variable effect on perceived verticality. Finally, we propose how the population-coding network for gravity direction might implement the elements required for the well-known perceptual underestimation of the subjective visual vertical in tilted body positions.

Vestibular-evoked myogenic potentials and subjective visual vertical testing in patients with vitamin D deficiency/insufficiency

Otolith function in subjects with vitamin D deficiency/insufficiency is investigated through vestibular-evoked myogenic potentials (VEMP) and subjective visual vertical (SVV) testing. The study group included 62 patients with vitamin D deficiency/insufficiency (30 females, 32 males), with age range 24-56 years (40.6 ± 9.1). The control group included 44 healthy volunteers of similar age and gender distribution. The entire study group had: (1) serum level of 25-hydroxyvitamin D <30 ng/ml; (2) normal bone mineral density as indicated by dual-energy X-ray absorptiometry with T-score >-1; (3) normal middle ear function; (4) Age is ≤60 years. All subjects enrolled in the current study underwent audiovestibular evaluation consisting of pure-tone audiometry, immittancemetry, cervical VEMP (cVEMP), ocular VEMP (oVEMP), and SSV. The entire control group had normal cVEMP, two subjects had abnormal oVEMP. Thirty-three subjects (53%) in the study group had abnormal oVEMP and 31 subjects (50%) had abnormal cVEMP. Forty-one (66%) had abnormal VEMP when abnormal VEMP was considered as either abnormal oVEMP or cVEMP. The entire control and study groups had normal SSV test results. Vitamin D deficiency may be associated with development of otolith dysfunction affecting both the utricle and saccule. This was suggested by the high prevalence of abnormal ocular vestibular-evoked myogenic potentials (oVEMP) and cervical vestibular-evoked myogenic potentials (cVEMP) in the study group.

A pathway in the brainstem for roll-tilt of the subjective visual vertical: evidence from a lesion-behavior mapping study

The perceived subjective visual vertical (SVV) is an important sign of a vestibular otolith tone imbalance in the roll plane. Previous studies suggested that unilateral pontomedullary brainstem lesions cause ipsiversive roll-tilt of SVV, whereas pontomesencephalic lesions cause contraversive roll-tilts of SVV. However, previous data were of limited quality and lacked a statistical approach. We therefore tested roll-tilt of the SVV in 79 human patients with acute unilateral brainstem lesions due to stroke by applying modern statistical lesion-behavior mapping analysis. Roll-tilt of the SVV was verified to be a brainstem sign, and for the first time it was confirmed statistically that lesions of the medial longitudinal fasciculus (MLF) and the medial vestibular nucleus are associated with ipsiversive tilt of the SVV, whereas contraversive tilts are associated with lesions affecting the rostral interstitial nucleus of the MLF, the superior cerebellar peduncle, the oculomotor nucleus, and the interstitial nucleus of Cajal. Thus, these structures constitute the anatomical pathway in the brainstem for verticality perception. Present data indicate that graviceptive otolith signals present a predominant role in the multisensory system of verticality perception.

Central Vertigo

Central vertigo can clinically manifest in three ways: Acute onset of vertigo and dizziness, recurrent attacks and chronic central vertigo. In patients with acute onset of symptoms it is essential to differentiate between central and peripheral vertigo because this has major diagnostic and therapeutic implications. A differentiation can most often be achieved by a careful neuroophthalmological and neuro-otological bedside examination. One should look in particular for the following five signs of central lesions: skew deviation/vertical divergence (as a component of the ocular tilt reaction), gaze-evoked nystagmus contralateral to a spontaneous nystagmus, saccadic smooth pursuit, acute nystagmus in combination with a nonpathological head-impulse test and central fixation nystagmus. The most frequent forms of central vertigo with recurrent attacks are vestibular migraine and episodic ataxia type 2. Clinically relevant types of chronic or chronic progressive central vertigo are neurodegenerative disorders affecting the cerebellum which are often associated with cerebellar ocular motor dysfunction, in particular downbeat nystagmus. Treatments of choice for a prophylactic therapy of vestibular migraine are betablocker, topiramate or valproic acid. A new treatment option for episodic ataxia type 2 and downbeat nystagmus are aminopyridines (potassium channel blockers).

How to cite this article

Strupp M, Brandt T. Central Vertigo. Otorhinolaryngol Clin Int J 2012;4(2):71-76.