Vestibular asthenopia

Vestibular asthenopia, analogous to visual asthenopia, is a sensory (or sensory-motor) discomfort consisting of a set of subjective symptoms, the expression of which is essentially visual and whose origin is a transient vestibular incident. It can be considered the result of a sudden global central disorder, such as a "computer glitch," following a chain of events in response to an initial vestibular disease, even minor and devoid of clinical signs. This disorder results in inadequate processing and imperfect integration of afferent visual and vestibular input, leading to ocular fatigue, pain associated with eye movement, and sensitivity to retinal slip.

Postural control characterization according to age and auditory input in cochlear implant users

Aims/Objectives: Understand the relationship between auditory input and balance motor control. Material and Methods: Twelve prelingual adolescent cochlear implant users (CIU) and 12 adult postlingual CIU were tested by posturography on a force platform with eyes open in two conditions, with the cochlear implant (CI) on and off. Energy consumption (EC) of the body center of pressure sway signal was measured, calculating total EC and divided into three bands of frequencies; low (B1) 0-0.1 Hz, medium (B2) 0.1-1 Hz, and high (B3)1-2 Hz. Wilcoxon and Mann-Whitney tests were used for statistical analysis and the significance level was P ≤ 0.05. Results: Prelingual CIU decrease the EC in low and high frequencies throughout the adolescence (P < 0.05) assessed with the CI turned on, while it did not show any modification with the CI off. Postlingual CIU showed a deterioration of PR related to aging when evaluated with the CIU turned off, P < 0.05 in band 1. However, with the CI turned on they had no significant increase in this age range. Conclusions and Significance: The acoustic input improved EC of postural responses in higher and lower frequencies in adolescence and with aging which suggests a relationship with gross and fine movements involved in postural control.

Impaired math achievement in patients with acute vestibular neuritis

Broad cognitive difficulties have been reported in patients with peripheral vestibular deficit, especially in the domain of spatial cognition. Processing and manipulating numbers relies on the ability to use the inherent spatial features of numbers. It is thus conceivable that patients with acute peripheral vestibular deficit show impaired numerical cognition. Using the number Stroop task and a short math achievement test, we tested 20 patients with acute vestibular neuritis and 20 healthy, age-matched controls. On the one hand, patients showed normal congruency and distance effects in the number Stroop task, which is indicative of normal number magnitude processing. On the other hand, patients scored lower than healthy controls in the math achievement test. We provide evidence that the lower performance cannot be explained by either differences in prior math knowledge (i.e., education) or slower processing speed. Our results suggest that peripheral vestibular deficit negatively affects numerical cognition in terms of the efficient manipulation of numbers. We discuss the role of executive functions in math performance and argue that previously reported executive deficits in patients with peripheral vestibular deficit provide a plausible explanation for the lower math achievement scores. In light of the handicapping effects of impaired numerical cognition in daily living, it is crucial to further investigate the mechanisms that cause mathematical deficits in acute PVD and eventually develop adequate means for cognitive interventions.

Acute peripheral vestibular deficit increases redundancy in random number generation

Unilateral peripheral vestibular deficit leads to broad cognitive difficulties and biases in spatial orientation. More specifically, vestibular patients typically show a spatial bias toward their affected ear in the subjective visual vertical, head and trunk orientation, fall tendency, and walking trajectory. By means of a random number generation task, we set out to investigate how an acute peripheral vestibular deficit affects the mental representation of numbers in space. Furthermore, the random number generation task allowed us to test if patients with peripheral vestibular deficit show evidence of impaired executive functions while keeping the head straight and while performing active head turns. Previous research using galvanic vestibular stimulation in healthy people has shown no effects on number space, but revealed increased redundancy of the generated numbers. Other studies reported a spatial bias in number representation during active and passive head turns. In this experiment, we tested 43 patients with acute vestibular neuritis (18 patients with left-sided and 25 with right-sided vestibular deficit) and 28 age-matched healthy controls. We found no bias in number space in patients with peripheral vestibular deficit but showed increased redundancy in patients during active head turns. Patients showed worse performance in generating sequences of random numbers, which indicates a deficit in the updating component of executive functions. We argue that RNG is a promising candidate for a time- and cost-effective assessment of executive functions in patients suffering from a peripheral vestibular deficit.

Audiovestibular consequences of congenital cytomegalovirus infection

Congenital cytomegalovirus (CMV) infection is the second most frequent cause of mental retardation and sensorineural hearing loss, after genetic factors. Recently, pediatric forensic and fetopathological studies have led to progress in understanding the pathophysiological mechanisms underlying the various neurosensory sequelae. Thanks to the identification of certain prognostic factors of hearing loss, therapeutic protocols based on antiviral molecules are now proposed for target populations. This treatment has shown efficacy in limiting hearing threshold deterioration and even, in some cases, seems to provide partial recovery of hearing in symptomatic congenitally infected CMV neonates. However, optimal treatment duration and administration modalities are not clearly defined. This article reviews recent data concerning audiovestibular sequelae and their management in children congenitally infected by CMV.

Disrupted functional connectivity of the default mode network due to acute vestibular deficit

Vestibular neuritis is defined as a sudden unilateral partial failure of the vestibular nerve that impairs the forwarding of vestibular information from the labyrinth. The patient suffers from vertigo, horizontal nystagmus and postural instability with a tendency toward ipsilesional falls. Although vestibular neuritis is a common disease, the central mechanisms to compensate for the loss of precise vestibular information remain poorly understood. It was hypothesized that symptoms following acute vestibular neuritis originate from difficulties in the processing of diverging sensory information between the responsible brain networks. Accordingly an altered resting activity was shown in multiple brain areas of the task-positive network. Because of the known balance between the task-positive and task-negative networks (default mode network; DMN) we hypothesize that also the DMN is involved.

Here, we employ functional magnetic resonance imaging (fMRI) in the resting state to investigate changes in the functional connectivity between the DMN and task-positive networks, in a longitudinal design combined with measurements of caloric function. We demonstrate an initially disturbed connectedness of the DMN after vestibular neuritis. We hypothesize that the disturbed connectivity between the default mode network and particular parts of the task-positive network might be related to a sustained utilization of processing capacity by diverging sensory information. The current results provide some insights into mechanisms of central compensation following an acute vestibular deficit and the importance of the DMN in this disease.

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fMRI connectivity analyses after vestibular neuritis in a longitudinal design

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Initially disturbed connectedness between the DMN and task positive networks

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Connectivity restoration after complete clinical recovery of patients