Vestibular modulation of skin sympathetic nerve activity in sopite syndrome induced by low-frequency sinusoidal motion.

Sopite syndrome, centered around the drowsiness, lethargy, and irritability associated with motion sickness, can be induced by exposure to low-frequency motion. It is known that the vestibular apparatus plays an important role in the pathogenesis of motion sickness, which features several autonomic responses, and we have previously documented increased vestibular modulation of skin sympathetic nerve activity (SSNA) and an increase in skin blood flow associated with nausea. Here, we assessed whether imperceptibly slow sinusoidal motion, sufficient to induce sopite syndrome but not nausea, also modulates SSNA and skin blood flow. Participants were seated upright and exposed to a randomized set of sinusoidal linear accelerations, ranging from 0.03 Hz at 0.5 mG to 0.2 Hz at 5 mG, via a motorized platform. At all frequencies vestibular modulation was greater than the cardiac modulation of SSNA, but cardiac modulation and skin blood flow were both significantly lower during the motion than at baseline. We conclude that sopite syndrome is associated with a marked modulation of sympathetic outflow to the skin and cutaneous vasoconstriction.NEW & NOTEWORTHY Little is known about the autonomic consequences of sopite syndrome-the drowsiness that can be induced by low-amplitude cyclic motion. We recorded skin sympathetic nerve activity (SSNA) in seated participants exposed to slow sinusoidal linear acceleration (0.03-0.2 Hz), which preferentially activates hair cells in the utricular part of the otolithic organs, at amplitudes that generated no sensations of motion. At all frequencies, there was a clear vestibular modulation of SSNA and cutaneous vasoconstriction.

Hearing eyeball and/or eyelid movements on the side of a unilateral superior semicircular canal dehiscence.

Hearing of eyeball movements has been reported in superior semicircular canal dehiscence (SSCD), but not hearing of eyelid movements. Our main objective was to report the hearing of eyeball and/or eyelid movements in unilateral SSCD. Our secondary objective was to access its specificity to SSCD and discuss the underlying mechanism. Six patients with SSCD who could hear their eyeball and/or eyelid movements were retrospectively reviewed. With the aim of comparisons, eight patients with an enlarged vestibular aqueduct (EVA), who share the same mechanism of an abnormal third window, were questioned on their ability to hear their eyeball and/or eyelid movements. Three patients with SSCD could hear both their eyeball and eyelid movements as a soft low-pitch friction sound. Two patients with SSCD could hear only their eyelid movements, one of whom after the surgery of a traumatic chronic subdural hematoma. The latter remarked that every gently tapping on the skin covering the burr-hole was heard in his dehiscent ear as the sound produced when banging on a drum, in keeping with a direct transmission of the sound to the inner ear via the cerebrospinal fluid. One patient with SSCD, who could hear only his eyeball movements, had other disabling symptoms deserving operation through a middle fossa approach with an immediate relief of his symptoms. None of the eight patients with EVA could hear his/her eyeball or eyelid movements. Hearing of eyeball and/or eyelid movements is highly suggestive of a SSCD and do not seem to occur in EVA. In case of radiological SSCD, clinicians should search for hearing of eyeball and/or eyelid movements providing arguments for a symptomatic dehiscence. The underlying mechanism is discussed particularly the role of a cerebrospinal fluid transmission.

SLC26A4 targeted to the endolymphatic sac rescues hearing and balance in Slc26a4 mutant mice.

Mutations of SLC26A4 are a common cause of human hearing loss associated with enlargement of the vestibular aqueduct. SLC26A4 encodes pendrin, an anion exchanger expressed in a variety of epithelial cells in the cochlea, the vestibular labyrinth and the endolymphatic sac. Slc26a4 (Δ/Δ) mice are devoid of pendrin and develop a severe enlargement of the membranous labyrinth, fail to acquire hearing and balance, and thereby provide a model for the human phenotype. Here, we generated a transgenic mouse line that expresses human SLC26A4 controlled by the promoter of ATP6V1B1. Crossing this transgene into the Slc26a4 (Δ/Δ) line restored protein expression of pendrin in the endolymphatic sac without inducing detectable expression in the cochlea or the vestibular sensory organs. The transgene prevented abnormal enlargement of the membranous labyrinth, restored a normal endocochlear potential, normal pH gradients between endolymph and perilymph in the cochlea, normal otoconia formation in the vestibular labyrinth and normal sensory functions of hearing and balance. Our study demonstrates that restoration of pendrin to the endolymphatic sac is sufficient to restore normal inner ear function. This finding in conjunction with our previous report that pendrin expression is required for embryonic development but not for the maintenance of hearing opens the prospect that a spatially and temporally limited therapy will restore normal hearing in human patients carrying a variety of mutations of SLC26A4.

Cochlear implantation in patients with inner ear bone malformations with posterior labyrinth involvement: an exploratory study.

Inner ear bone malformations are one cause of profound sensorineural hearing loss. This investigation focused on those affecting the posterior labyrinth, especially enlarged vestibular aqueduct syndrome, which is associated with fluctuating and progressive hearing loss. The objectives of this study were to analyze the behavior of the electrical stimulation, auditory functionality and linguistic development in patients with inner ear malformations involving the posterior labyrinth. The study included ten patients undergoing cochlear implantation (cases: five with enlarged vestibular aqueduct, two with vestibular aqueduct stenosis/aplasia, and three with semicircular canal disorders). Post-implantation, data were gathered on the electrical stimulation threshold and maximum comfort levels and on the number of functioning electrodes. Evaluation of Auditory Responses to Speech (EARS) subtests were used to assess auditory functionality and language acquisition at 6, 12, and 24 months post-implantation. Results were compared with findings in a control group of 28 cochlear implantation patients without these malformations. No significant differences were found between case and control groups in electrical stimulation parameters; auditory functionality subtest scores were lower in cases than controls, although the difference was only statistically significant for some subtests. In conclusion, cochlear implantation patients with posterior labyrinth bone malformations and profound hearing loss, including those with enlarged vestibular aqueduct syndrome, showed no significant difference in electrical stimulation threshold with controls. Although some auditory functionality test results were lower in cases than in controls, cochlear implantation appears to be beneficial for all patients with these malformations.

[Enlarged vestibular aqueduct syndrome: etiology, clinical features, diagnostics, and rehabilitation of the patients].

This publication was designed to describe the clinical manifestations of the enlarged vestibular aqueduct syndrome (EVAS), the currently employed methods for its diagnostics, and the strategy for the rehabilitation of the patients presenting with this pathological condition. In addition, the article provides information about the topographic anatomy and X-ray anatomy of the vestibular aqueduct, the specific clinical features of EVAS, the modern algorithm of its diagnostics, and the facilities for hearing rehabilitation in this group of patients.

Augmented ocular vestibular evoked myogenic potentials to air-conducted sound in large vestibular aqueduct syndrome.

OBJECTIVE: To demonstrate the value of recording air-conducted ocular Vestibular Evoked Myogenic Potentials (oVEMP) in a patient with bilaterally enlarged vestibular aqueducts. DESIGN: Cervical VEMP and oVEMP were recorded from a patient presenting with bilateral hearing loss and imbalance, attributable to large vestibular aqueduct syndrome. The stimuli were air-conducted tone bursts at octave frequencies from 250 to 2000 Hz. Amplitudes and thresholds were measured and compared with the normal response range of 32 healthy control subjects. RESULTS: oVEMP reflexes demonstrated pathologically increased amplitudes and reduced thresholds for low-frequency tone bursts. Cervical VEMP amplitudes and thresholds were within normal limits for both ears across all frequencies of stimulation. CONCLUSIONS: This study is the first to describe the augmentation of AC oVEMPs in an adult with large vestibular aqueduct syndrome.

Audiological and radiological characteristics of a family with T961G mitochondrial mutation.

OBJECTIVE: The aim of this study was to describe audiological and radiological characteristics, and other secondary aspects, in a family carrying a T961G mutation in the 12S rRNA mitochondrial gene. DESIGN: Case report. STUDY SAMPLE: Six members of a family participated in an audiological evaluation that included pure-tone audiometry, immittance tests, auditory brainstem responses (ABR), and otoacoustic emissions (OAE). The radiological evaluation was conducted through temporal bone CT scans using a Toshiba 16 channels Aquilon Spirale. Neuropsychiatric evaluation was also administered. RESULTS: Three participants were diagnosed with severe sensorineural hearing loss of cochlear origin and cochlear malformations visible in CT scans. One participant had a mild mixed-hearing loss and no cochlear malformations. Two participants had normal audiological and radiological findings. CONCLUSIONS: We believe our study can provide helpful insight on the clinical findings of a rare mutation, of which few data have been presented in literature.

Extremely discrepant mutation spectrum of SLC26A4 between Chinese patients with isolated Mondini deformity and enlarged vestibular aqueduct.

BACKGROUND: Mutations in SLC26A4 cause Pendred syndrome (hearing loss with goiter) or DFNB4 (non-syndromic hearing loss with inner ear malformation, such as enlarged vestibular aqueduct or Mondini deformity). The relationship between mutations in SLC26A4 and Mondini deformity without enlarged vestibular aqueduct has not been studied in any Chinese deaf population. The purpose of this study was to assess whether mutations in the SLC26A4 gene cause Mondini deformity without an enlarged vestibular aqueduct (isolated Mondini deformity) in a Chinese population. METHODS: In total, 144 patients with sensorineural hearing loss were included and subjected to high-resolution temporal bone CT. Among them, 28 patients with isolated Mondini dysplasia (MD group), 50 patients with enlarged vestibular aqueduct with Mondini dysplasia (EVA with MD group), 50 patients with enlarged vestibular aqueduct without Mondini dysplasia (EVA group), and 16 patients with other types of inner ear malformations (IEM group) were identified. The coding exons of SLC26A4 were analyzed in all subjects. RESULTS: DNA sequence analysis of SLC26A4 was performed in all 144 patients. In the different groups, the detection rate of the SLC26A4 mutation differed. In the isolated MD group, only one single allelic mutation in SLC26A4 was found in one patient (1/28, 3.6%). In the EVA with MD group, biallelic and monoallelic SLC26A4 mutations were identified in 46 patients (46/50, 92.0%) and three patients (3/50, 6.0%), respectively. Also, in the EVA group, biallelic and monoallelic SLC26A4 mutations were identified in 46 patients (46/50, 92.0%) and three patients (3/50, 6.0%), respectively. These percentages were identical to those in the EVA plus MD group. Only two patients carried monoallelic mutations of the SLC26A4 gene in the IEM group (2/16, 12.5%). There were significant differences in the frequency of SLC26A4 mutation among the groups (P<0.001). The detection rate of SLC26A4 mutation in the isolated MD group was significantly lower than in the EVA group (with or without MD; P<0.001), and there was no significant difference in the detection rate of SLC26A4 between the MD group and IEM group (P>0.5). CONCLUSION: Although mutations in the SLC26A4 gene were frequently found in Chinese EVA patients with and without MD, there was no evidence to show a relationship between isolated MD and the SLC26A4 gene in the Chinese population examined. Hearing impairment in patients with isolated MD may be caused by factors other than mutations in the SLC26A4 gene.

Air and bone-conducted vestibular evoked myogenic potentials in children with large vestibular aqueduct syndrome.

BACKGROUND: There are few studies focused on vestibular symptoms and function of the children with LVAS. OBJECTIVES: This study aimed to find the characteristics of air and bone-conducted VEMPs among children with LVAS, and to investigate the relationship between VEMPs and vestibular symptoms. MATERIAL AND METHODS: A total of 44 children with LVAS and 10 healthy children were recruited as the case group and control group. Air and bone-conducted VEMP were performed to the participants. RESULTS: For air-conducted measurement, there was elevated amplitude of cVEMP in case group than control group. There was no significant difference at oVEMP parameters between the case group and control group. For bone-conducted measurement, significantly longer P1 latency and shorter P1-N1 latency of cVEMP were observed among the case group; there were a series of changes in oVEMP parameters among the case group. Logistic regression model revealed that air-conducted oVEMP asymmetric ratio was valuable to predict vestibular symptoms' development among the kids with LVAS. CONCLUSION: Asymmetric ratio of oVEMP could be used as one predictor of developing vestibular symptoms of the children with LVAS. Applying bone-conducted VEMP as one alternative parameter of vestibular syndrome is novel and will certainly remain an area of continued investigation.

The biomechanical characteristics of human vestibular aqueduct: a numerical-based model construction and simulation.

Vestibular aqueduct is a precise structure embedded in the temporal bone and plays a key role in the physiological function of inner ear by maintaining the endolymphatic circulation and buffering the impact from intracranial pressure. Although the alterations on the morphology or volume of vestibular aqueduct result in variety of diseases, the approaches of evaluating the condition of vestibular aqueduct are still unsatisfing because the pathological sections utilized for the 3D construction model most likely undergoes morphological changes. In this study, the vestibular aqueduct images obtained by CT scanning were processed by finite element method to construct the 3D model. To assess if this numerical model reflects the actual biomechanical properties of vestibular aqueduct, the fluid-solid coupling calculation was applied to simulate the endolymphatic flow in the vestibular aqueduct. By measuring the dynamics of endolymphatic flow, and the pressure and displacement on round membrane under external pressure, we found the numerical 3D model recapitulated the biomechanical characteristics of the real vestibular aqueduct. In summary, our approach of 3D model construction for vestibular aqueduct will provide a powerful method for the research of vestibular aqueduct-related diseases.

Inner ear pressure evaluation using wideband tympanometry in children with Large Vestibular Aqueduct Syndrome (LVAS): A pilot study.

OBJECTIVE: To investigate middle ear function in children with Large Vestibular Aqueduct Syndrome (LVAS) to explore the feasibility of measuring inner ear pressure using Wideband tympanometry (WBT). METHODS: 13 young children with LVAS were recruited. WBT and other audiological measurements i.e., Auditory Steady State Response (ASSR), Auditory Brain Stem Response (ABR), and Distorted Product Otoacoustic Emissions (DPOAE) were performed. Absorbance under ambient and peak pressure were compared with normative data, and analyzed using a one sample t-test. RESULTS: Average absorbance in children with LVAS was significantly lower than normative data under ambient pressure at 1000, 1189, 1296, 2000 Hz and 4000 Hz. Absorbance under peak pressure was also significantly lower at 707, 794, 917, 1000, 1189, 1297, 1498 and 2000 Hz. However, absorbance was higher than standard values above 4000 Hz under ambient and peak pressure. It was also higher under ambient pressure at frequencies below 500 Hz. CONCLUSION: The special characteristics of middle ear function found in children with Large Vestibular Aqueduct Syndrome (LVAS) indicate that WBT offers a sensitive and non-invasive method to evaluate inner ear pressure indirectly.

Grades of hearing loss affect the presence of acoustically evoked short latency negative responses in children with large vestibular aqueduct syndrome.

OBJECTIVES: We aimed to investigate the relationship between grades of hearing loss and the presence of acoustically evoked short latency negative response (ASNR) in children with large vestibular aqueduct syndrome (LVAS), so as to enhance the reference value of ASNR for the diagnosis of LVAS in children. METHODS: Two hundred sixteen ears from 108 patients (aged 4-90 months) diagnosed with bilateral LVAS, with slight to profound hearing loss, were enrolled in the present study from January 2012 to December 2018. All of the cases were diagnosed with LVAS according to high-resolution computed tomography (HRCT) or magnetic resonance imaging (MRI) scans of the inner ears. The auditory brain stem response (ABR) tests were performed on these subjects with click stimulus (ck-ABR), and the ASNRs were detected based on the method recommended by previous studies. The degree of hearing loss for each ear was classified by the estimated pure-tone average (PTA) thresholds, which were calculated according to the ck-ABR thresholds. RESULTS: ASNRs were present in 40.7% (88/216) ears during ck-ABR tests. Both thresholds of ABR (Z = 2.977, p = 0.003) and estimated PTA (Z = 2.977, p = 0.003) were significantly higher in the ASNR absent group than in the ASNR present group. The frequency of not profound hearing impairment (≤80 dB HL) was much higher in the ASNR present group (44/88; 50%) than in the ASNR absent group (40/128; 31.3%) (χ2 = 7.714, p = 0.005). The results of the logistic regression model, adjusted by cases' age and gender, showed that compared with those ears with profound hearing impairment (>80 dB HL), the not profound impaired ears were associated with a 2.48-fold increased odds of recording ASNR presence in the ck-ABR test [odds ratio (OR) = 2.48, 95% confidence interval (CI): 1.38-4.46, p = 0.003]. CONCLUSIONS: Grades of hearing loss affect the presence of ASNR in children with LVAS, and manifesting as cases with not profound hearing impairment showed increased odds of recording ASNR in the ck-ABR test. Furthermore, more studies should be performed imperatively to determine the diagnosis value of ASNR in children with LVAS.

Enlarged vestibular aqueduct: Intraoperative electrocochleography findings during cochlear implantation.

Enlarged vestibular aqueduct (EVA) is the most frequent inner ear abnormality found on computed tomography in children with sensorineural hearing loss. The effects EVA abnormalities have on electrocochleography (ECochG) are unknown. Positive deflections in summation potential evoked by tone bursts were observed in 3/5 subjects, while a large negative deflection, similar to endolymphatic hydrops (EH), was observed for 2/5 subjects. The presence of an enlarged summation potential, with and without a compound action potential, was observed in response to a broadband click stimulus. Results suggest likely effects of a third window on ECochG responses and presence of EH in EVA.

Auditory Detection Thresholds and Cochlear Resistivity Differ Between Pediatric Cochlear Implant Listeners With Enlarged Vestibular Aqueduct and Those With Connexin-26 Mutations.

Purpose The goal of this study was to evaluate differences in the electrode-neuron interface as a function of hearing loss etiology in pediatric cochlear implant (CI) listeners with enlarged vestibular aqueduct (EVA) syndrome and in those with autosomal recessive connexin-26 mutations (DFNB1). Method Fifteen implanted ears (9 participants, 5 ears with EVA, 10 ears with DFNB1) were assessed. Single-channel auditory detection thresholds were measured using broad and spatially focused electrode configurations (steered quadrupolar; focusing coefficients = 0 and 0.9). Cochlear resistivity estimates were obtained via electrode impedances and electrical field imaging. Between-group differences were evaluated using linear mixed-effects models. Results Children with EVA had significantly higher auditory detection thresholds than children with DFNB1, irrespective of electrode configuration. Between-group differences in thresholds were more pronounced on apical electrodes than on basal electrodes. In the apex, electrode impedances and electrical field imaging values were higher for children with EVA than for those with DFNB1. Conclusions The electrode-neuron interface differs between pediatric CI listeners with DFNB1 and those with EVA. It is possible that optimal clinical interventions may depend, in part, on hearing loss etiology. Future investigations with large samples should investigate individualized CI programming strategies for listeners with EVA and DFNB1.

Biomechanical analysis of the clinical characteristics of enlarged vestibular aqueduct syndrome with Mondini malformation.

BACKGROUND: numerous researches on the pathological mechanism of Enlarged Vestibular Aqueduct (EVA) syndrome mainly focuses on the genetic characteristics of SLC26A4 gene and the function of its encoding protein, Pendrin. One of the limitations with these explanations is that it does not explain why cerebrospinal fluid pressure can affect clinical manifestations. OBJECTIVES: To establish a new approach to explain the clinical manifestations of EVA syndrome with biomechanical method. MATERIAL AND METHODS: 108 cases of EVA syndrome who received cochlear implantation were analyzed retrospectively. A cochlear model was built to reflect the differences of the structure in EVA syndrome with or without Mondini malformation. The CFD software was used to simulate and display the differences in mechanical pathogenic factors to which the model was subjected. RESULTS: EVA syndrome patients with Mondini malformation suffer more mechanical damage from the cerebrospinal fluid pressure due to their structural reason and their symptoms appear earlier and progress faster. CONCLUSIONS: Biomechanics is an important aspect of pathological mechanism of EVA syndrome, and it provides a new angle for clinical decision-making.

Communication routes between intracranial spaces and inner ear: function, pathophysiologic importance and relations with inner ear diseases.

OBJECTIVE: There exist 3 communication routes between the intracranial space and the inner ear, the vestibular aqueduct, the cochlear aqueduct, and the internal auditory canal. They possess a key role in inner ear pressure regulation and fluid homeostasis and are related to inner ear diseases. REVIEW METHODS: Relevant literature was reviewed, and the current knowledge of the anatomy, physiologic importance, and relations to inner ear diseases were described. Pathologic communication routes such as semicircular canal dehiscence syndrome were highlighted as well. CONCLUSION: Abnormalities in all 3 communication routes may predispose or be the cause of distinct inner ear pathologic condition and involved in other cochlear and vestibular syndromes, in which their role is not completely clear. The increasing knowledge of the underlying mechanisms encourages promising approaches for possible intervention in the future.

[Imaging characteristics of patients with large vestibular aqueduct syndrome and its relationship with the acoustically evoked short latency negative response].

Objective: To explore the imaging characteristics of large vestibular aqueduct syndrome (LVAS) patients and their relationship with the acoustically evoked short latency negative response (ANSR), so as to provide reference for the diagnosis of LVAS. Methods: Clinical data of 174 patients(334 ears) with LVAS diagnosed and treated by the Department of Otorhinolaryngology Head and Neck Surgery of the First Affiliated Hospital of Guangxi Medical University, from October 2009 to December 2017 were retrospectively analyzed, including 117 males and 57 females, aged from 5 months to 47 years old, with the median age of 4 years and 4 months. ABR and imaging data of patients were collected. Midpoint diameter and the outlet diameter of the vestibular aqueduct were measured on CT images, the midpoint diameter of the intraosseous parts and the extraosseous parts of enlarged endolymphatic sac(EES) were measured on MRI images. The correlation between the above measurements was analyzed by Pearson test using SPSS 17.0. According to whether ASNR was detected in ABR, the above data were divided into two groups, and the differences of the above imaging measurements were compared by the Independent-Sample Test. Results: The average midpoint diameter of the vestibular aqueduct was (1.87±0.58) mm (x±s, the following was the same), and the outlet diameter was (3.07±0.99) mm on CT; the average midpoint diameter of the intraosseous parts in enlarged endolymphatic sac(EES) was (2.39±1.37) mm, and the extraosseous parts was (2.50±2.18) mm on MRI. There was a correlation between the four measurements (P<0.05), among which the midpoint diameter of vestibular aqueduct was strongly positively correlated with the outlet diameter (r=0.760), and the remaining pairs were weakly correlated. ASNR was detected in 241 ears (72.16%,241/334) and undetected in 93 ears (27.84%, 93/334) of the 334 ears with LVAS. Midpoint diameter and the outlet diameter of the vestibular aqueduct in no ASNR group were smaller than the ASNR group, and the difference was statistically significant (t value was 2.814 and 2.754, P<0.05). There was no significant difference in the midpoint diameter of the intraosseous parts and the extraosseous parts of enlarged endolymphatic sac between the two groups, and the difference was no statistically significant(t value was 0.101 and 0.683, P>0.05). Conclusions: There is a strong positive correlation between the midpoint diameter of vestibular aqueduct and the outlet diameter in LVAS patients. There is a certain correlation between the size of vestibular aqueduct and the size of endolymphatic sac. The smaller the diameter of vestibular aqueduct, the lower the occurrence rate of ASNR.

Causation of permanent unilateral and mild bilateral hearing loss in children.

Children with permanent unilateral or mild bilateral hearing loss have been a focus of concern by audiologists, educators, and physicians for at least 2 decades. These children are known to be at risk for psychoeducational difficulties. However, despite this concern, little has been learned about the causative factors of these hearing losses and how those factors might be contributing to child development. This review of known causes of permanent unilateral and mild bilateral hearing loss in children is meant to draw attention to the importance of the search for etiologic factors. That is, the identification of the hearing loss should not signal the end of the diagnostic process but, rather, the beginning of a search for causation. With the combined efforts of audiologists, otolaryngologists, pediatricians, geneticists, and other medical professionals, we may enhance our understanding of the primary causes of unilateral and mild bilateral hearing loss and, perhaps, create links between causative factors and psychosocial and psychoeducational outcomes.

Enlarged vestibular aqueduct (EVA) related with recurrent benign paroxysmal positional vertigo (BPPV).

The vestibular aqueduct is a bony canal related to the bony labyrinth of the inner ear and represents the non-sensory components of the endolymph-filled, closed, membranous labyrinth. The association of congenital sensorineural hearing loss with a large or enlarged vestibular aqueduct is well known as the large vestibular aqueduct syndrome (LVAS). The enlarged VA (EVA) comprises abnormalities not only in the structure of the inner ear, but also in the physiology of the auditory and vestibular systems. The clinical picture of this clinical entity is variable [Yetiser S, Kertment M, Ozkaptan Y. Vestibular disturbance in patients with Large Vestibular Aqueduct Syndrome (LVAS). Acta Otolaryngol (StochK) 1999;119: 641-646]. Signs and symptoms of the auditory impairment are more commonly described in the literature: hearing loss ranges from mild to profound, arising from fluctuating to stepwise progressive or sudden. Vestibular disturbances, ranging from mild imbalance to episodic vertigo, are rarely described in the literature. Benign paroxysmal positional vertigo (BPPV) is a labyrinthine disorder with a typical behavior: intense crises of rotational vertigo induced by postural changes of the head, with short duration and usually good responsiveness to rehabilitative maneuvers. These maneuvers are effective in about 80% of patients with BPPV. BPPV often recurs. About 1/3 of patients have a recurrence in the first year after treatment, and by five years, about half of all patients have a recurrence. Vestibular aqueduct has been demonstrated by conventional tomography and computed tomography (CT), however, CT scans cannot show the membranous labyrinth itself. On MR images it is not the vestibular aqueduct that is visualized but its contents, the endolymphatic duct and sac, and can show the abnormalities of the fluid spaces related to the membranous labyrinth. It is proposed that recurrent benign paroxysmal positional vertigo (BPPV) is related with volumetric abnormalities of vestibular aqueduct. This verifiable hypothesis tries to define this rapport and explore new diagnostic and therapeutic possibilities.

The Giant Hand Illusion Experienced on a Simulator.

BACKGROUND: This paper discusses a special kind of a sensory illusion-the Giant Hand illusion-that was experienced during an exercise on a flight simulator equipped with a VR headset. In the first part we describe spatial disorientation and the function of the vestibular apparatus during flight and its consequences. In this part, the sensory illusion simulator used for the experiment is mentioned. In the second part we describe the simulator and test flight. In the third part we discuss data retrieved during simulator flights that are important for explaining the Giant Hand illusion. CASE REPORT: A well-trained pilot experienced the Giant Hand illusion while executing instrument flight rules flight on a simulator. The Giant Hand illusion was detected from the simulation data and confirmed by the pilot afterward. DISCUSSION: The Giant Hand illusion is a rare type of sensory illusion. The pilot falsely evaluated the situation as a malfunction of the aircraft controls. If the pilot had not been informed by the operator that he might have been influenced by the illusion, he would probably have crashed the simulated aircraft. An unrecognized Giant Hand illusion during a flight can lead to fatal consequences. This case report shows the symptoms and data that can be used for early recognition of this type of illusion.Frantis P, Petru A. The Giant Hand illusion experienced on a simulator. Aerosp Med Hum Perform. 2018; 89(6):557-562.