Search

Background: Acute and complete unilateral vestibular deafferentation induces a significant change in ipsilateral vestibuloocular reflex gain, making the patient unable to stabilize gaze during active or passive head movements. This inability creates the illusion that the visual environment is moving, resulting in persistent visual discomfort during rapid angular or linear acceleration of the head. This is known as oscillopsia. Our objective was to understand if the spontaneous sensation of oscillopsias after complete unilateral vestibular deafferentation by vestibular neurotomy at 5 days (D5) and at 3 months (M3) is correlated with the loss of vestibuloocular reflex gain and dynamic visual acuity., Methods: Retrospective cohort study was conducted in an otolaryngology tertiary care center (2019-2022) on patients with complete unilateral vestibular loss by vestibular neurotomy. They were divided into 2 groups according to the presence (group G1) or absence (group G2) of a spontaneous complaint of oscillopsia assessed at M3. Severity of oscillopsias evaluated by Oscillopsia Severity Questionnaire. Vestibuloocular reflex gain based on video head impulse test (vHIT) and the dynamic visual acuity were measured for each group at D5 and M3. Categorical variables were compared using χ 2 test and quantitative variables using the nonparametric Wilcoxon-Mann-Whitney test., Results: All patients have a complete vestibular deafferentation at D5 and M3. At D5 (G1 = 8 patients, G2 = 5 patients), there is no significant difference for ipsilateral and contralateral vestibuloocular reflex gains and dynamic visual acuity losses. The Oscillopsia Severity Questionnaire was 2.68 ± 1.03 in G1 and 1.23 ± 1.03 in G2 ( P  < .05). At M3 (G1 = 9 patients, G2 = 6 patients), there is no significant difference between groups for epidemiologic and clinical data and for vestibuloocular reflex and dynamic visual acuity losses. The Oscillopsia Severity Questionnaire was 2.10 ± 0.63 in G1 and 1.24 ± 0.28 in G2 ( P  < .05)., Conclusions: The spontaneous disabling sensation of oscillopsia after complete unilateral vestibular loss is well assessed by the Oscillopsia Severity Questionnaire but cannot be explained by objective vestibular tests assessing vestibuloocular reflex gain (vHIT) or dynamic visual acuity loss at D5 or M3. Further studies are needed to measure the sensation of oscillopsia under real-life conditions and to identify the factors responsible for its persistence., Trial Registration: Retrospectively registered., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Introduction: This study compares the balance control and cognitive responses of subjects with bilateral vestibulopathy (BVP) to those of astronauts immediately after they return from long-duration spaceflight on board the International Space Station., Methods: Twenty-eight astronauts and thirty subjects with BVP performed five tests using the same procedures: sit-to-stand, walk-and-turn, tandem walk, duration judgment, and reaction time., Results: Compared to the astronauts' preflight responses, the BVP subjects' responses were impaired in all five tests. However, the BVP subjects' performance during the walk-and-turn and the tandem walk tests were comparable to the astronauts' performance on the day they returned from space. Moreover, the BVP subjects' time perception and reaction time were comparable to those of the astronauts during spaceflight. The BVP subjects performed the sit-to-stand test at a level that fell between the astronauts' performance on the day of landing and 1 day later., Discussion: These results indicate that the alterations in dynamic balance control, time perception, and reaction time that astronauts experience after spaceflight are likely driven by central vestibular adaptations. Vestibular and somatosensory training in orbit and vestibular rehabilitation after spaceflight could be effective countermeasures for mitigating these post-flight performance decrements., Competing Interests: GC and TM were employed by the company KBR. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2023 Clément, Kuldavletova, Macaulay, Wood, Navarro Morales, Toupet, Hautefort, Van Nechel, Quarck and Denise.)

Background: The management of dizziness and vertigo can be challenging in the emergency department (ED). It is important to rapidly diagnose vertebrobasilar stroke (VBS), as therapeutic options such as thrombolysis and anticoagulation require prompt decisions., Objective: This study aims to assess the rate of misdiagnosis in patients with dizziness caused by VBS in the ED., Methods and Results: The cohort was comprised of 66 patients with a mean age 56 years; 48% were women and 52% men. Among dizzy patients, 14% had VBS. We used Cohen's kappa test to quantify the agreement between two raters -namely, emergency physicians and neurologists -regarding the causes of dizziness in the ED. The Kappa value was 0.27 regarding the final diagnosis of central vertigo disorders and VBS, thus showing the low agreement. We used the χi2 test to show the association between the presence of two or more cardiovascular risk factors and admission to the stroke unit (p = 0.015)., Conclusion: There is a substantial rate of misdiagnosis in patients with dizziness caused by VBS in the ED. To reduce the number of missing diagnoses of VBS in the future, there is a need to train emergency physicians in neurovestibular examinations, including the HINTS examination for acute vestibular syndrome (AVS) and the Dix-Hallpike (DH) maneuver for episodic vestibular syndrome. Using video head impulse test could help reduce the rate of misdiagnosis of VBS in the ED.

During navigation, humans mainly rely on egocentric and allocentric spatial strategies, two different frames of reference working together to build a coherent representation of the environment. Spatial memory deficits during navigation have been repeatedly reported in patients with vestibular disorders. However, little is known about how vestibular disorders can change the use of spatial navigation strategies. Here, we used a new reverse T-maze paradigm in virtual reality to explore whether vestibular loss specifically modifies the use of egocentric or allocentric spatial strategies in patients with unilateral (n = 23) and bilateral (n = 23) vestibular loss compared to healthy volunteers (n = 23) matched for age, sex and education level. Results showed that the odds of selecting and using a specific strategy in the T-maze were significantly reduced in both unilateral and bilateral vestibular loss. An exploratory analysis suggests that only right vestibular loss decreased the odds of adopting a spatial strategy, indicating an asymmetry of vestibular functions. When considering patients who used strategies to navigate, we observed that a bilateral vestibular loss reduced the odds to use an allocentric strategy, whereas a unilateral vestibular loss decreased the odds to use an egocentric strategy. Age was significantly associated with an overall lower chance to adopt a navigation strategy and, more specifically, with a decrease in the odds of using an allocentric strategy. We did not observe any sex difference in the ability to select and use a specific navigation strategy. Findings are discussed in light of previous studies on visuo-spatial abilities and studies of vestibulo-hippocampal interactions in peripheral vestibular disorders. We discuss the potential impact of the history of the disease (chronic stage in patients with a bilateral vestibulopathy vs. subacute stage in patients with a unilateral vestibular loss), of hearing impairment and non-specific attentional deficits in patients with vestibular disorders., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.)

There are tight functional and anatomical links between the vestibular and interoceptive systems, and both systems have shown to fundamentally underlie emotional processes and our sense of a bodily self. Yet, nothing is known about how long-term bilateral vestibulopathy (BVP) influences interoception and its relation to embodiment and the sense of self. We thus compared cardiac interoceptive accuracy, confidence in the performance, and general body awareness in 25 BVP patients and healthy controls using a heartbeat tracking task, self-reports about interoceptive awareness, as well as measures of self-localization and of self-body closeness. Results showed no difference between patients and controls regarding interoceptive accuracy, confidence and body awareness, suggesting that long-term BVP does not influence cardiac interoception. Patients and controls did not differ either regarding self-location and self-body closeness. However, in our overall sample of patients and controls, we found that interoceptive accuracy increased with perceived self-body closeness, suggesting that anchoring the self to the body is generally linked with better cardiac interoception. This result is in line with previous suggestions of an important contribution of interoception to the sense of embodiment.

Purpose: Bilateral vestibulopathy (BV) is an uncommon disorder and the etiology remained idiopathic in most cases. Delayed 3D-FLAIR sequences have provided new insights into various inner ear diseases, allowing the evaluation of the endolymphatic space and the permeability of the blood-labyrinthine barrier (BLB). The aim of this study was to assess both the morphology of the endolymphatic space and the permeability of the BLB in patients with BV as evaluated by delayed 3D-FLAIR sequences., Methods: In this retrospective study, we performed 3D-FLAIR sequences 4 h after administering contrast media to 42 patients with BV. Two radiologists independently evaluated the morphology of the endolymphatic space (either vestibular atelectasis or endolymphatic hydrops) and the permeability of the BLB., Results: Morphologic anomalies of the endolymphatic space and vestibular blood-labyrinthine barrier impairment were observed in 59.6% of patients with BV. Bilateral vestibular atelectasis (VA) was found in 21 patients (50%), involving only the utricle and all three ampullas while the saccule was always observed with no sign of collapse: idiopathic BV (n = 19), aminoglycoside administration (n = 1) and few days following abdominal surgery (n = 1). One patient had bilateral vestibular malformation. BLB impairment was observed in five patients (11.9%): paraneoplastic (n = 1), lymphoma (n = 1), autoimmune (n = 1), and vestibular "neuritis" (n = 2). Seventeen patients (40.4%) had normal MRI with no endolymphatic space anomaly or BLB impairment., Conclusion: Patients with BV presented with morphologic anomalies of the endolymphatic space or BLB impairment in 59.6% of patients.

Objective: The aim of this study was to investigate the relation between visual and vestibular hypersensitivity, and Depersonalization/Derealization symptoms in patients with chronic dizziness. Materials and Methods: 319 adult patients with chronic dizziness for more than 3 months (214 females and 105 males, mean age: 58 years, range: 13-90) were included in this prospective cross-sectional study. Patients underwent a complete audio-vestibular workup and 3 auto questionnaires: Hospital Anxiety and Depression (HAD), Depersonalization/Derealization Inventory (DDI), and an in-house questionnaire (Dizziness in Daily Activity, DDA) assessing 9 activities with a score ranging from 0 (no difficulty) to 10 (maximal discomfort) and 11 (avoidance) to detect patients with visual and vestibular hypersensitivity (VVH, a score > 41 corresponding to mean + 1 standard deviation). Results: DDI scores were higher in case of VVH (6.9 ± 6.79, n = 55 vs. 4.2 ± 4.81, n = 256 without VVH, p < 0.001, unpaired t- test), migraine (6.1 ± 6.40, n = 110 vs. 4.0 ± 4.42, n = 208no migraine, p < 0.001, unpaired t- test), and motion sickness (6.8 ± 5.93, n = 41 vs. 4.4 ± 5.11, n = 277 no motion sickness, p < 0.01, unpaired t- test). Women scored DDI higher than men (5.1 ± 5.42, n = 213 vs. 3.9 ± 4.91, n = 105, respectively, p < 0.05, unpaired t- test). DDI scores were also related to depression and anxiety. DDI score was also higher during spells than during the basal state. Conclusion: During chronic dizziness, Depersonalization/Derealization symptoms seem to be related to anxiety and depression. Moreover, they were prominent in women, in those with visual and vestibular hypersensitivity, migraine, and motion sickness.

Patients with vestibular deficit use slow eye movements or catch-up saccades (CUS) to compensate for impaired vestibulo-ocular reflex (VOR). The purpose of CUS is to bring the eyes back to the visual target. Covert CUS occur during high-velocity head rotation and overt CUS are generated after head rotation has stopped. Dynamic visual acuity is improved with an increased rate and gain of CUS. Nevertheless, the trigger and the parametric determinants of CUS are still under debate. To clarify the underlying mechanism, especially the visual contribution, we analyzed the number, amplitude and latencies of the CUS in relation with the extent of VOR deficiency. The head and eye movements were recorded in 17 patients with bilateral vestibular loss (BVL) and in 33 subjects with normal VOR gain using the Video Head Impulse Test (vHIT) in two conditions: with visible target and in darkness with an imaginary target. Our study shows that in darkness without visible target the number of CUS is significantly reduced and the relationship between the amplitude of CUS and gaze position error is lost. Results showed that there is a correlation between the number of CUS and the drop in VOR gain. CUS occurring during the head movement and when the head remained still were not always sufficiently accurate. Up to four consecutive CUS could be required to bring eyes back to the visible target. A positive correlation was found between the amplitude of overt saccades with visible target and the gaze position error, namely the remaining eye movement to reach the target. These results suggest that the visual inputs are the main trigger and parametric determinant of the CUS or at least the presence of a visual target is necessary in most cases for a CUS to occur.

Chronic patients with bilateral vestibular hypofunction (BVH) complain of oscillopsia and great instability particularly when vision is excluded and on irregular surfaces. The real nature of the visual input substituting to the missing vestibular afferents and improving posture control remains however under debate. Is retinal slip involved? Do eye movements play a substantial role? The present study tends to answer this question in BVH patients by investigating their posture stability during quiet standing in four different visual conditions: total darkness, fixation of a stable space-fixed target, and pursuit of a visual target under goggles delivering visual input rate at flicker frequency inducing either slow eye movements (4.5 Hz) or saccades (1.2 Hz). Twenty one chronic BVH patients attested by both the caloric and head impulse test were examined by means of static posturography, and compared to a control group made of 21 sex-and age-matched healthy participants. The posturography data were analyzed using non-linear computation of the center of foot pressure (CoP) by means of the wavelet transform (Power Spectral Density in the visual frequency part, Postural Instability Index) and the fractional Brownian-motion analysis (stabilogram-diffusion analysis, Hausdorff fractal dimension). Results showed that posture stability was significantly deteriorated in darkness in the BVH patients compared to the healthy controls. Strong improvement of BVH patients' posture stability was observed during fixation of a visual target, pursuit with slow eye movements, and saccades, whereas the postural performance of the control group was less affected by the different visual conditions. It is concluded that BVH patients improve their posture stability by (1) using extraocular signals from eye movements (efference copy, muscle re-afferences) much more than the healthy participants, and (2) shifting more systematically than the controls to a more automatic mode of posture control when they are in dual-task conditions associating the postural task and a concomitant visuo- motor task.

The European Society for Clinical Evaluation of Balance Disorders - ESCEBD - Executive Committee meets yearly to identify and address clinical equilibrium problems that are not yet well understood. This particular discussion addressed "discordances" (defined as "lack of agreement") in clinical assessment. Sometimes there is disagreement between a clinical assessment and measured abnormality (ies); sometimes the results within the assessment do not agree. This is sometimes thought of as "malingering" or an attempt to exaggerate what is wrong, but this is not always the case. The Committee discussed the clinical significance of unexpected findings in a patient's assessment. For example intraposturographic discordances sometimes exhibit findings (eg performance on more difficult trials may sometimes be better than on simpler trials). This can be suggestive of malingering, but in some situations can be a legitimate finding. The extreme malingerer and the genuine patient are at opposite ends of a spectrum but there are many variations along this spectrum and clinicians need to be cautious, as a posturography assessment may or may not be diagnostically helpful. Sometimes there is poor correlation between symptom severity and test results. Interpretation of posturography performance can at times be difficult and a patient's results must be correlated with clinical findings without stereotyping the patient. It is only in this situation that assessment in a diagnostic setting can be carried out in an accurate and unbiased manner.

The executive committee of the European Society for the clinical evaluation of balance disorders meets annually to address equilibrium problems that are not well understood. This is a review paper on discussions in the latest meeting we held., Materials and Methods: Seeing patients with vestibular disorders who end up depending on visual information as part of their compensation process is a common clinical occurrence. However, this "visual dependence" can generate symptoms, which include nausea, sensations of imbalance, and anxiety. It is unclear how this develops, as symptoms can be widely variable from patient to patient. There are several triggering factors to this symptom set, and quantifying it in a given patient is extremely difficult Results: The committee agreed that the presence of this symptom set can be suggestive of vestibular pathology, but the pathology does not have to be present. As a result, there is no correlation between symptom severity and test results., Conclusion: Visual dependence can often be present in a patient, although little, if any, measurable pathology is present. It is important to emphasize that although we cannot accurately measure this with either standardized testing or pertinent questionnaires, "hypersensitive" patients have a genuine disease and their symptoms are not of psychiatric origin.

Introduction: We aimed to study the participation of proprioceptive and visual inputs in subjective visual vertical (SVV) in bilateral vestibular hypofunction and in normal subjects., Study Design: Prospective case-control study., Setting: Tertiary referral center., Materials and Methods: SVV (six replicates) was measured on a tiltable rehabilitation seat in 26 adult patients with idiopathic bilateral vestibular hypofunction (IBVH) and 33 adult controls. Subjects were asked to place vertically a 45 degrees-tilted red line on a screen (three replicates to left and three to right alternatively) using a remote control in total darkness and in seven body positions: vertical, head, and body left- and right-tilts to 12 and 24 degrees, and then body left- and right-tilt to 24 degrees with the head upright., Results: In the vertical position, SVV did not differ between IBVH and controls. Patients with IBVH were more sensitive to body tilt than controls (SVV: -8.1 ± 4.66 degrees for IBVH versus -0.2 ± 3.23 for control at 24 degrees body and head left-tilt, p < 0.0001, unpaired t test). The visual attraction effect defined by a deviation of the SVV to the side of the initial line presentation appeared to be higher in the IBVH than in controls suggesting higher visual dependence in IBVH. Placing the head upright while the body was still tilted significantly reduced this difference. Similar results were observed for the right-tilts., Conclusion: Not only otolithic function but also visual plus body and neck proprioceptive entries participate in SVV. The influence of vision and proprioception appears to be enhanced in case of IBVH.

Recent findings suggest that vestibular information plays a significant role in anchoring the self to the body. Out-of-body experiences of neurological origin are frequently associated with vestibular sensations, and galvanic vestibular stimulation in healthy participants anchors the self to the body. Here, we provide the first objective measures of anchoring the self to the body in chronic bilateral vestibular failure (BVF). We compared 23 patients with idiopathic BVF to 23 healthy participants in a series of experiments addressing several aspects of visuo-spatial perspective taking and embodiment. In Experiment 1, participants were involved in a virtual "dot-counting task" from their own perspective or the perspective of a distant avatar, to measure implicit and explicit perspective taking, respectively. In both groups, response times increased similarly when the avatar's and participant's viewpoint differed, for both implicit and explicit perspective taking. In Experiment 2, participants named ambiguous letters (such as "b" or "q") traced on their forehead that could be perceived from an internal or external perspective. The frequency of perceiving ambiguous letters from an internal perspective was similar in both groups. In Experiment 3, participants completed a questionnaire measuring the experienced self/body and self/environment "closeness". Both groups reported a similar embodied experience. Altogether, our data show that idiopathic BVF does not change implicit and explicit perspective taking nor subjective anchoring of the self to the body. Our negative findings offer insight into the multisensory mechanisms of embodiment. Only acute peripheral vestibular disorders and neurological disorders in vestibular brain areas (characterized by strong multisensory conflicts) may evoke disembodied experiences., Competing Interests: The authors have declared that no competing interests exist.

Balance disorders may result from an impairment of one of the sensorial modalities involved in the perception of the self-location in space: vestibular, proprioception and vision, a deficit of the neuronal multisensorial integration, a less effective motor or loco-motor system, the medication side effects or psychological interferences. The basic examination of a dizzy patient implies the assessment of these different aspects. The balance is not restricted to à set of reflexes. It is a distinctive expression of the sixth sense : the sense of orientation. For every moving being, to go around in circles is ineffective to find new sources of food or avoid a predator. So, the ability of self-orientation in space is a primitive, unconscious function, critical to stay alive and closely related to the limbic system. The experience of the mobility, that required the spatial memory, which evolved towards the episodic memory, could be considered as the foundation of our thought.

Objective: The attraction of the subjective visual vertical (SVV) to the side of initial rod presentation has already been described in adults. The aim of this study was to evaluate this phenomenon in children and to analyze the effect of sex and maturation in this population., Study Design: Retrospective cross-sectional study., Setting: Tertiary referral center., Patients: Six hundred and one individuals aged between 4 and 19 years., Intervention: All subjects underwent a complete balance workup. SVV was measured by presenting a laser line 12 times in total darkness with a 45 degrees deviation from the vertical alternatively on the left and the right. The patient was seated and asked to replace the bar vertically with a remote control., Results: On average, SVV was tilted to the side of the rod presentation at each iteration. The cumulative tilt to the side of presentation after 12 measures was higher in the 4 to 7 years age group and decreased progressively with age (25 ± 2.2 degrees in 4-7 years, n = 109 versus 5 ± 1.4 in 15-19 years, n = 204, p < 0.001, analysis of variance [ANOVA]). The cumulative tilt was higher in girls than in boys in the 15 to 19 years group (8 ± 2.5 degrees, n = 104 versus 2 ± 1.2, n = 100, respectively, p < 0.001, ANOVA). This phenomenon appeared independent from the type of vestibular disorder., Conclusion: Young children are highly attracted to the side of rod presentation during SVV measurements. This phenomenon gradually disappears with maturation, faster in boys than in girls.

Objective: The aim of this study was to evaluate the effect of initial rod position on the subjective visual vertical (SVV) tilt and to investigate the effect of sex and age on the SVV tilt induced by this initial position., Study Design: Prospective cross-sectional study., Setting: Tertiary referral center., Patients: The study included 6598 consecutive patients with a large range of vestibular disorders and 333 control subjects. The mean age was 55 years (range, 3-97), and the sex ratio was 0.6., Intervention: SVV was measured by presenting a phosphorescent rod 12 times in total darkness with a 45-degree deviation from the vertical alternatively on the right and left. The patient was asked to replace the bar vertically with a remote control., Results: On average, SVV at each iteration was tilted to the side of the rod presentation. It was stronger in female subjects, in younger individuals (<20 years) and seniors (>50). It was also higher in patients with a left vestibular loss in comparison to those with a right involvement., Conclusions: These effects suggest that short-term visual memory and multisensory cortical processing interfere with SVV measurements.

Purpose: The aim of this study was to identify the genetic cause of early-onset autosomal recessive cerebellar ataxia associated with retinal dystrophy in a consanguineous family., Methods: An affected 6-month-old child underwent neurological and ophthalmological examinations. Genetic analyses included homozygosity mapping, copy number analysis, conventional polymerase chain reaction, Sanger sequencing, quantitative polymerase chain reaction, and whole-exome sequencing. Expression analysis of GRID2 was performed by quantitative polymerase chain reaction and immunohistochemistry., Results: A homozygous deletion of exon 2 of GRID2 (p.Gly30&#95;Glu81del) was identified in the proband. GRID2 encodes an ionotropic glutamate receptor known to be selectively expressed in cerebellar Purkinje cells. Here, we demonstrated GRID2 expression in human adult retina and retinal pigment epithelium. In addition, Grid2 expression was demonstrated in different stages of murine retinal development. GRID2 immunostaining was shown in murine and human retina. Whole-exome sequencing in the proband did not provide arguments for other disease-causing mutations, supporting the idea that the phenotype observed represents a single clinical entity., Conclusion: We identified GRID2 as an underlying disease gene of early-onset autosomal recessive cerebellar ataxia with retinal dystrophy, expanding the clinical spectrum of GRID2 deletion mutants. We demonstrated for the first time GRID2 expression and localization in human and murine retina, providing evidence for a novel functional role of GRID2 in the retina.

Reliable knowledge of one's space is a prerequisite for effective action, and only sensory experience, although not alone sufficient, can provide access to knowledge of reality. All the diferent sensory modalities help to make sense of this mental construct, but visual information, when available, is predominant. This requires stable images and constant updating of one's awareness of gaze direction and position in space at the moment of acquisition. The vestibular system is sensitive to angular and linear accelerations and thus acts as a reference for stability--an inertial base which stabilizes and characterizes the gaze direction and encodes the subject's movement tracking. In clinical practice, loss of these capacities induces eye drift, nystagmus, oscillopsia, vertical eye misalignment and a shift in the representation of mental space, leading to dizziness, translational illusions, integration path error, and "senseless" perceptions of the self in space. The reaction time of the eye and of mental image stabilization is of the order of afew tens of milliseconds. Recent tools for vestibular exploration allow us to measure this reactivity, which is a determining factor for quality of life. The video head impulse test, dynamic visual acuity, and cervical vestibular evoked myogenic potentials explore the structures involved in gaze and image stabilization, while subjective visual vertical and ocular vestibular evoked myogenic potentials provide an approach to the utricular contribution. This clinical and instrumental semiology sometimes proves more sensitive than the most advanced and accurate medical imaging methods, but rational listening and multidisciplinary skills on the part of the physician remain necessary to identify "self in space perceptual alterations.

The subjective visual vertical (SVV) is an indicator of vestibular otolithic function and mainly processed by the nondominant parietal cortex. We investigated the hypothesis that recovery from SVV tilt after vestibular neuritis can be influenced by the body's lateral preference. This prospective cohort follow-up study included 254 consecutive adult patients with vestibular neuritis. The recovery from SVV tilt was faster in patients with a left hand or eye dominance than in those with a right dominance. While in left-handers the side of the neuritis did not affect the speed of recovery, in right-handed subjects, the recovery from a right-sided neuritis was significantly slower than from a left-sided affection. These observations suggest that subjects with a left sensorimotor dominance have developed more significant midline-crossing projections to the parietal cortex, allowing them to cope faster with a unilateral vestibular deficit.

There are five possible ocular signs or complaints of a life or sight threatening neuro-ophthalmological condition: diplopia, isolated anisocoria, transient visual loss, severe pain in head or neck (with or without photophobia) and oscillopsia/nystagmus. In this review, the ocular signs and symptoms of neuro-ophthalmological emergencies are described together with their practical work-up and the risks associated with missing the diagnosis. Concerning diplopia, the associated signs pointing to a possible threatening condition are emphasized. Six focus points resuming core messages are displayed throughout this review.

The aim of this study was to determine whether there is more deterioration in walking under dual-task conditions in patients with bilateral vestibular loss (BVL) than in healthy subjects, as opposed to the findings after unilateral loss. For this purpose, 12 patients with BLV and 12 healthy control subjects performed 3 tasks: walking along a 10-m walkway, counting backwards by two, and both tasks simultaneously. Patients did not differ from controls in their walking speed in the single task condition, or in their cognitive performance in both the single and dual-task conditions. However, walking performance was more affected in patients than in controls under dual-task conditions, as shown by slower gait speed in the dual-task, higher reduction in gait speed from single to dual-task, and lower global dual-score. These findings provide evidence for greater attentional interference between walking and counting in patients with BVL., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Purpose: Optic nerve aplasia (ONA, OMIM 165550) is a very rare unilateral or bilateral condition that leads to blindness in the affected eye, and is usually associated with other ocular abnormalities. Although bilateral ONA often occurs in association with severe congenital anomalies of the brain, nonsyndromic sporadic forms with bilateral ONA have been described. So far, no autosomal-dominant nonsyndromic ONA has been reported. The genetic basis of this condition remains largely unknown, as no developmental genes other than paired box gene 6 (PAX6) are known to be implicated in sporadic bilateral ONA., Methods: The individuals reported underwent extensive ophthalmological, endocrinological, and neurologic evaluation, including neuroimaging of the visual pathways. In addition genomewide copy number screening was performed., Results: Here we report an autosomal-dominant form of nonsyndromic ONA in a Belgian pedigree, with unilateral microphthalmia and ONA in the second generation (II:1), and bilateral ONA in two sibs of the third generation (III:1; III:2). No PAX6 mutation was found. Genome wide copy number screening revealed a microdeletion of maximal 363 kb of chromosome 10q23.33q23.33 in all affected individuals (II:1, III:1; III:2) and in unaffected I:1, containing three genes: exocyst complex component 6 (EXOC6), cytochrome p450, subfamily XXVIA, polypeptide 1 (CYP26A1), and cytochrome p450, subfamily XXVIC, polypeptide 1 (CYP26C1). The latter two encode retinoic acid-degrading enzymes., Conclusions: This is the first study reporting an autosomal-dominant form of nonsyndromic ONA. The diagnostic value of neuroimaging in uncovering ONA in microphthalmic patients is demonstrated. Although involvement of other genetic factors cannot be ruled out, our study might point to a role of CYP26A1 and CYP26C1 in the pathogenesis of nonsyndromic ONA.

This report identifies fundamental problems to be addressed in order to build relevant clinical tests of human balance while standing. The stated purpose of these tests is identification of lesion site and/or definition of functional balance deficits in a specific patient. During a recent consensus meeting (ESCEBD), 60 researchers and experienced clinical users of posturography (14 European countries, 9 different disciplines) inventoried and critically analyzed the various methodologies of posturography currently used for clinical evaluation. To complement posturography, alternative methods of assessment of balance control were considered. The indications for the clinical use of posturography were defined as well as recommendations regarding measurement parameters, type of perturbations and signal analysis techniques to improve assessment of balance control. Consensus was reached that a force platform cannot be considered as a technique which is sufficient on its own to perform a clinically relevant test for the assessment of neuro-otological and musculo-skeletal conditions, evaluation of compensation or treatment (rehabilitation) or prediction of falls. It should be supported by complementary methods, such as segment motion analysis, body-fixed 2D or 3D accelerometer-gyroscope or electromyography. At present, no generally applicable posturography test is available with reasonable sensitivity and specificity for the diagnosis of balance disorders. Perturbation techniques are most likely needed to enhance the diagnostic yield of posturography.

During mental actions subjects feel themselves performing a movement without any corresponding motor output. Although broad information is available regarding the influence of central lesions on action representation, little is known about how peripheral damages affect mental events. In the current study, we investigated whether lack of vestibular information influences action representation. Twelve healthy adults and twelve patients with bilateral vestibular damage actually performed and mentally simulated walking and drawing. The locomotor paths implied one (first walking task) and four (second walking task) changes in the walking direction. In the drawing task, participants drew on a sheet of paper a path that was similar to that of the second walking task. We recorded and compared between the two groups the timing of actual and mental movements. We found significant temporal discrepancies between actual and mental walking movements in the group of patients. Conversely, drawing actual and drawing mental durations were similar. For the control group, an isochrony between mental and actual movements was observed for the three tasks. This result denotes an inconsistency between action representation and action execution following vestibular damage, which is specific to walking movements, and emphasizes the role of the vestibular system upon mental states of actions. This observation may have important clinical implications. During action planning vestibular patients may overestimate the capacity of their motor system (imaging faster, executing slower) with harmful consequences for their health.

Purpose: To document for the first time intrinsic retinal pigment epithelium (RPE) fluorescence in occult macular dystrophy (OMD). This entity is characterized by a central cone dysfunction leading to a decline of visual acuity without visible fundus and fluorescein angiography abnormalities. A great variability in clinical findings and in the pattern of inheritance have been reported suggesting probably several etiologies of which some are well known but seen too early to detect significant changes., Methods: Fundus autofluorescence imaging is a recent method to detect early retinal pigment epithelial alterations. It may visualise disease specific abnormalities in the retinal pigment epithelium often not yet visible on ophthalmoscopy such as Stargardt disease, rod-cone dystrophy. This method was applied in a member of a family with OMD., Results: The normal fundus autofluorescence observed in our patient allowed the distinction between well-known maculopathies not yet visible on ophthalmoscopy but showing abnormal autofluorescence, and genuine occult macular dystrophy., Conclusion: Fundus autofluorescence imaging in our case of dominant autosomal OMD suggests a healthy and functional RPE. This examination of RPE should therefore be added to the work-up of suspected OMD.

Many medicines, mainly with neurological purpose, interfere with the oculomotricity. The biochemistry of the oculomotor systems and thus, the mechanisms of action of these drug interferences are not completely clarified. Most medicines impair the eye movements at the level of their fine adjustment by feed-back loops implying the cerebellum. Quite often, the interferences remain asymptomatic, restricted to a saccadic pursuit, hypometric saccades or an end-point nystagmus. Sometimes however, symptoms of dizziness or oscillopsia appear, due to loss of the vestibulo-ocular reflexes efficiency. A diplopia or a blurred vision by double outline could be suggestive of an ocular motor paresis or a loss of the binocular fusion due to drugs action.

The aim of this topic is on one hand to pick out the semiological features which can quickly show the way of central nervous system lesions related to the vestibular system and on the other hand to describe these main central vestibular syndromes. A particular attention is carried to central otolithics syndromes which often remain undiagnosed. They induce imbalance, non rotatory vertigo, intolerance to linear acceleration and most often there is no nystagmus on examination. Neurophysiological diagram are restricted to a minimum useful to the clinician.