Visual Vestibular Interaction in the Dynamic Visual Acuity Test during Voluntary Head Rotation

Although intact vestibular function is essential in maintaining spatial orientation, no good screening tests of vestibular function are available to the aviation community. High frequency voluntary head rotation was selected as a vestibular stimulus to isolate the vestibulo-ocular reflex (VOR) from visual influence. A dynamic visual acuity test that incorporates voluntary head rotation was evaluated as a potential vestibular function screening tool. Twenty-seven normal subjects performed voluntary sinusoidal head rotation at frequencies from 0.7-4.0 Hz under three different visual conditions: visually-enhanced VOR, normal VOR, and visually suppressed VOR. Standardized Baily-Lovie chart letters were presented on a computer monitor in front of the subject, who then was asked to read the letters while rotating his head horizontally. The electro-oculogram and dynamic visual acuity score were recorded and analyzed. There were no significant differences in gain or phase shift among three visual conditions in the frequency range of 2.8 to 4.0 Hz. The dynamic visual acuity score shifted less than 0.3 logMAR at frequencies under 2.0 Hz. The dynamic visual acuity test at frequencies a round 2.0 Hz can be recommended for evaluating vestibular function

Efficacy and Tolerability of Antimalarials and Molecular Resistance Markers of Falciparum Malaria in Jimma Region, Ethiopia

Due to increasing drug resistance, artemisinin-based combination chemotherapy (ACT) has become the first-line treatment of falciparum malaria in many endemic countries. Ethiopia has also adopted artemether/lumefantrine (AL) as first-line treatment in 2004 and its broad introduction was achieved in 2006. However, irreversible ototoxicity associated with AL has been reported and suggested to be a serious limitation in the use of ACT. The aim of this study was to compare ototoxicity, tolerability, and efficacy of ACT with that of quinine and atovaquone/proguanil in the treatment of uncomplicated falciparum malaria. 97 patients in Jimma area, Ethiopia with slide-confirmed malaria were randomly assigned to receive either artemether/lumefantrine or quinine or atovaquone/proguanil and followed-up on days 7, 28, and 90. Comprehensive audio-vestibular testing by pure tone audiometry (PTA), transitory evoked (TE) and distortion product (DP) otoacoustic emissions (OAE) and brain stem evoked response audiometry (BERA) was done before enrolment and on follow-up days. PTA and DP-OAE levels revealed transient significant cochlear hearing loss in patients treated with quinine but not in those treated with artemether/lumefantrine or atovaquone/proguanil. There was no evidence of drug-induced brain stem lesions by BERA measurements. Hence, there was no detrimental effect of a standard oral regimen of artemether/lumefantrine on peripheral hearing or brainstem auditory pathways in patients with uncomplicated falciparum malaria. In contrast, transient hearing loss was evidenced with quinine therapy due to temporary outer hair cell dysfunction. Reinfection and recrudescence were determined by RFLP of msp-1 and msp-2 genes. Mutations associated with drug resistance were characterized in Pfmdr1, Pfdhfr, Pfcytb, and Pfserca genes. Single nucleotide polymorphisms (SNPs) previously reported to be associated with resistance to the study drugs were identified in both recrudescent and treatment sensitive isolates. A total of seven recrudescences were obtained. The Pfmdr1 N86Y mutation was found in 84.5% of isolates. The triple mutation 51I, 59R, 108N of the Pfdhfr gene occurred in high frequency (83.3%) but no Pfcytb mutation was detected. Sequencing showed a variety of previously described and new mutations in the Pfserca gene. The prevalence of high degree of mutations in Pfmdr1 and Pfdhfr is a reminiscent of the impact of previously used drugs in the area, chloroquine and sulfadoxine/pyrimethamine as first-line treatments. The broad introduction of AL and the cessation of the former drug regimens might probably change the current distribution of polymorphisms, possibly leading to decreased sensitivity to AL in the future. Continuous surveillance of molecular patterns in this region is, therefore, recommended

Translational medical bioengineering research of traumatic brain injury among Chinese and American pedestrians caused by vehicle collision based on human body finite element modeling

Based on the average human body size in China and the THUMS AM50 finite element model of the human body, the Kriging interpolation algorithm was used to model the Chinese 50th percentile human body, and the biological fidelity of the model was verified. We built three different types of passenger vehicle models, namely, sedan, sports utility vehicle (SUV), and multi-purpose vehicle (MPV), and used mechanical response analysis and finite element simulation to compare and analyze the dynamic differences and head injury differences between the Chinese 50th percentile human body and the THUMS AM50 model during passenger vehicle collisions. The results showed that there are obvious differences between the Chinese mannequin and THUMS in terms of collision time, collision position, invasion speed, and angle. When a sedan collided with the mannequins, the skull damage to the Chinese human body model was more severe, and when a sedan or SUV collided, the brain damage to the Chinese human body was more severe. The abovementioned results suggest that the existing C-NCAP pedestrian protection testing regulations may not provide the best protection for Chinese human bodies, and that the regulations need to be improved by combining collision damage mechanisms and the physical characteristics of Chinese pedestrians. This thorough investigation is positioned to shed light on the fundamental biomechanics and injury mechanisms at play. Furthermore, the amalgamation of clinically rooted translational and engineering research in the realm of traumatic brain injury has the potential to establish a solid foundation for discerning preventive methodologies. Ultimately, this endeavor holds the potential to introduce effective strategies aimed at preventing and safeguarding against traumatic brain injuries

Vestibulotoxicity Associated With Platinum-Based Chemotherapy in Survivors of Cancer: A Scoping Review

Background: Cochleotoxicity following the treatment with platinum-based chemotherapy is well documented. The potential for vestibulotoxicity is still unclear. This scoping review examined the extent of current research literature, summarized research findings and identified research gaps regarding vestibular-related adverse effects associated with platinum-based chemotherapy in survivors of cancer.Methods: Inclusion criteria followed the PICO principles: Participants, adult, and pediatric cancer patients of any cancer type; Intervention, platinum-based chemotherapy (such as cisplatin, carboplatin, and oxaliplatin); Control, none or any; Outcomes, vestibular-related adverse effects. English language articles published since 1978 were retrieved. Seventy-five eligible studies were identified from a systematic literature search, and relevant data were charted, collated, and summarized.Results: Testing for vestibulotoxicity predominately featured functional evaluation of the horizontal semicircular canal using the caloric and rotational tests. The rate of abnormal vestibular function test results after chemotherapy administration varied from 0 to 50%. The results of objective testing did not always correspond to patient symptoms. There is tentative support for patients with pre-existing loss of vestibular function to be more likely to experience vestibular toxicity after dosing with cisplatin.Conclusions: A number of studies reported significant evidence of vestibular toxicities associated with platinum-based chemotherapy, especially cisplatin. This scoping review emphasizes that vestibular toxicity needs more attention and comprehensive evaluation. Specifically, studies that analyse cumulative dose of platinum-based chemotherapy, affected sites of lesion in vestibular end organs, and the correlation and temporal patterns of cochlear and vestibular toxicity are needed

振子様回転刺激に対する前庭眼反射の定量分析

Article信州医学雑誌 43(1): 53-67(1995)journal articl

Wearable Sensors Applied in Movement Analysis

Recent advances in electronics have led to sensors whose sizes and weights are such that they can be placed on living systems without impairing their natural motion and habits. They may be worn on the body as accessories or as part of the clothing and enable personalized mobile information processing. Wearable sensors open the way for a nonintrusive and continuous monitoring of body orientation, movements, and various physiological parameters during motor activities in real-life settings. Thus, they may become crucial tools not only for researchers, but also for clinicians, as they have the potential to improve diagnosis, better monitor disease development and thereby individualize treatment. Wearable sensors should obviously go unnoticed for the people wearing them and be intuitive in their installation. They should come with wireless connectivity and low-power consumption. Moreover, the electronics system should be self-calibrating and deliver correct information that is easy to interpret. Cross-platform interfaces that provide secure data storage and easy data analysis and visualization are needed.This book contains a selection of research papers presenting new results addressing the above challenges

Compensatory strategies in humans performing active and passive gaze fixation and re-fixation tasks after unilateral vestibular deafferentation

The human vestibulo-ocular reflex (VOR) stabilizes gaze during head movement. The reflex is typically tested in a clinic or laboratory using passive rotations or artificial stimuli which measure the amount of damage the vestibular apparatus has suffered. However, during everyday activities the vestibular system is stimulated by active, self generated head movements. Head movements are often rapid and associated with the goal of achieving either gaze-fixation or re-fixation. Patients who complain of on-going symptoms will typically identify a particular position or movement that aggravates their symptoms in their everyday life. There is a need to identify objective parameters which correlate with the subjective complaints of patients whose symptoms persist after vestibular damage. In the first study, a gaze-refixation task, patients who complain of ongoing symptoms (poorly-compensated), during rapid head turns, after unilateral vestibular de-afferentation (uVD) were compared with those who did not have the same complaints (well-compensated) and normal subjects. Well- and poorly-compensated groups were sorted according to responses on a standardized questionnaire. All subjects were then located in a real-world, non-laboratory environment in which poorly-compensated subjects reported experiencing symptoms. Each subject’s head, eye and gaze displacement and velocity, head rotation frequency and blink or eye-lid closure were measured and analysed and compared between ipsi- and contra-lesional head rotations within and between subject groups. When subjects are able to generate their own active head rotations it has been suggested that a number of vestibular and extra-vestibular strategies might be employed to compensate for an impaired VOR. In subsequent studies, high resolution scleral search coils were used to identify the compensatory mechanisms used during active head rotations during a gaze-fixation task. A corrective saccade is typically observed during passive ipsilesional head rotations or “impulses” and might be potentiated during rapid, active or self-generated head rotations. The conditions which predict or contribute to the generation of the rapid, corrective eye movement were investigated. The results were compared with responses to passive head impulses of matched velocity and acceleration to determine if active head impulses could be used to identify a lesioned vestibular apparatus as is routinely clinically achieved with passive head impulses

Variability of High Frequency Head Rotation Test in Normal Subjects

Functions of macular organ have not been understood completely, but the function of the saccular macula is considered to be different from that of the utricular macula as a peripheral vestibular receptor organ. Because distinctive secondary vestibular projections arise from particular regions within individual vestibular nucleus, the pattern of termination of primary vestibular fibers has special functional significance. So projection patterns of the saccular macula and the utricular macula to the vestibular nuclei were investigated in the 16 Mongolian gerbils applying the scratch method and HRP. The results were as follows: 1) In superior vestibular nucleus, afferent fibers from the utricular macula(AFU) projected to the lateral part and afferent fibers from the saccular macula(AFS) Projected to the periphery with concentration on the lateral part. 2) In lateral vestibular nucleus, AFU projected to the ventral part and AFS projected to the lateral part. 3) In medial vestibular nucleus, AFU projected to the central part in the rostral half of the nucleus and the dorsal part in the caudal half of the nucleus, but AFS projected to the ventral part in the rostral portion and the dorsal part in the mid portion of the nucleus, but not to the caudal part of the nucleus. 4) In descending vestibular nucleus, AFU projected to the lateral part, but AFS projected diffusely. 5) Both AFU and AFS projected to interstitial nucleus, but in group Y projections were observed only from AFS.ope

Active head rotation in benign positional paroxysmal vertigo Da rotação cefálica ativa na vertigem posicional paroxística benigna

Benign Positional Paroxysmal Vertigo (BPPV) is one of the most common vestibular diseases and the active head rotation test one of the most modern methods of vestibular function assessment. AIM: this study aims to verify if the active head rotation test may reveal signs of horizontal and/or vertical vestibulo-ocular reflex dysfunction in vertigo patients suspected for BPPV. STUDY DESIGN: retrospective series study. MATERIALS AND METHOD: Neurotological evaluation including computerized electronystagmography and active head rotation on the horizontal and vertical axes were conducted in 100 patients suspected for BPPV patients. Results: Isolated or associated abnormalities of the horizontal and/or vertical vestibulo-ocular reflex gain, phase and symmetry were indicative of vestibular involvement and found in 77.0% of the BPPV patients. CONCLUSION: the active head rotation test revealed horizontal and/or vertical vestibulo-ocular reflex dysfunctions in a relevant number of BPPV patients.A vertigem posicional paroxística benigna (VPPB) corresponde a uma das vestibulopatias mais comuns e a rotação cefálica ativa um dos métodos mais modernos de avaliação da função vestibular. OBJETIVO: O objetivo desta pesquisa foi verificar se a prova de rotação cefálica ativa pode revelar sinais de disfunção do reflexo vestíbulo-ocular horizontal e/ou vertical em pacientes vertiginosos com hipótese diagnóstica de VPPB. DESENHO DO ESTUDO: Estudo de série retrospectivo. MATERIAL E MÉTODO: Uma avaliação otoneurológica incluindo a eletronistagmografia computadorizada e a prova de rotação cefálica ativa, no plano horizontal e vertical foi conduzida em 100 pacientes com hipótese diagnóstica de VPPB. Resultados: Alterações isoladas ou associadas de ganho, fase e assimetria do reflexo vestíbulo-ocular horizontal e/ou vertical, foram os achados indicativos de comprometimento vestibular em 77,0% dos casos de VPPB. CONCLUSÃO: A prova de rotação cefálica ativa permitiu evidenciar distúrbios do reflexo vestíbulo-ocular horizontal e/ou vertical em relevante proporção dos pacientes com VPPB

Concurrent ENG and VNG recording in healthy people – preliminary report

Introduction: The aim of the work was to evaluate one-time recording of ENG and VNG in healthy subjects selected for the given diagnostic tests with reference to the sensitivity and usefulness of this kind of testing in vertigo diagnostics. Material and methods: The tests covered 50 healthy subjects, including 24 women and 26 men aged 20-22 (the mean age of 20,5 years) who did not report any inconvenience from otorhinolaryngological organs and the conducted interview did not reveal any balance disorder or vertigo. Every patient underwent otoneurological subjective and objective tests, electronystagmography (ENG), including a calibration test, head-tracking test, optokinetic nystagmus test, rotatory chair test, positional tests according to Cawthorne and Rose, a Hallpike caloric test as well as videonystagmography which included a calibration test, spontaneous nystagmus evaluation, head-tracking test, positional tests according to Cawthorne and Rose with a head rotation test and Hallpike caloric test. The above tests were performed separately, 24 hours one by one. One-time recording of ENG and VNG was made 48 hours following the last test while each of the two tests was preceded by an additional calibration test. The final recording included the spontaneous nystagmus evaluation, positional tests according to Cawthrone and Rose together with the head rotation test and Hallpike caloric test. Results: Any negative mutual influence of the conducted tests has not been observed. Both in the one-time and separate recording, the caloric test revealed lower values of the mean velocity of the nystagmus free phase in ENG with relation to VNG. No signs from spontaneous nystagmus, as well as optokinetic and positional nystagmus, could be found in any case. Conclusions: The conducted tests did not show any possibility of mutual exclusion of the given ENG and VNG diagnostic tests one-time recording. However, their use in diagnostics of balance disorders and vertigo requires further studie