bluuebunny/crossref_metadata_2025 huggingface dataset:
“Studying the cutaneous microcirculatory response during upper-limb exercise in healthy, older, sedentary people”
Authors: Klonizakis Markos
Published: December 2019

This study investigated changes incurred in cutaneous skin blood flux (SKBF) in the superficial veins of the lower limb by upper limb exercise training in the form of arm-cranking in 14 healthy participants over the age of 50 years. Changes in cutaneous microvascular function of the lower leg were assessed using laser Doppler Flowmetry (LDF) during a 30-minute exercise session undertaken over 4-exercise periods. Both SKBF and Time to reach Peak Perfusion (Tmax) were improved significantly during the 2nd (e.g. 121 (± 107.2) vs 280 (± 269.1) and 171 (± 34.4) vs. 247 (± 38.3) respectively) when compared to the first exercise period, while values approaching initial levels in the following stages. The results indicate that the thermoregulatory and vasodilation mechanisms observed during exercise in middle-aged and older healthy people are different to the one appearing in younger age groups, suggesting a more extensive effect of the age-related structural changes than it was previously thought.
Microvascular abnormalities in the bulbar conjunctiva of contact lens users
Authors: Cheung A.T.W. , Hu B.S. , Wong S.A. , Chow J. , Chan M.S. , To W.J. , Li J. , Ramanujam S. , Chen P.C.Y.
Published: December 2019

Soft contact lenses are commonly used to improve vision acuity or in cosmetic enhancement. We hypothesize that contact lens use can cause inadvertent damage to either the conjunctival microcirculation via direct vasoocclusion when the lens physically interacts with or damages the underlying vessels, or to the bulbar conjunctiva itself when the lens rests unevenly on the surface of the bulbar conjunctiva. Computer-assisted intravital microscopy was utilized to document (via video recording) and objectively quantify (via image analysis) real-time microvascular abnormalities resulting from changes and vessel remodeling in the conjunctival microcirculation in long-term (>2 yrs) contact lens users (n = 102), with non-users serving as control subjects (n = 29). A severity index (SI) – computed as the arithmetic sum of the abnormalities found in the conjunctival microcirculation in each contact lens user – was established for objective comparison with control subjects and critical interpretation. Contact lens user SI was significantly higher than control SI (user = 6.21 ± 1.26; control = 2.31 ± 1.49; p < 0.05), indicative of severe vasculopathy arising from contact lens use. The users also had significantly wider conjunctival vessel diameter (user = 71.25 ± 12.09 μm; control = 52.20 ± 5.10 μm; p < 0.05). Additional abnormalities, including damaged vessels, hemosiderin deposits (from damaged vessels or injury to the surface of the bulbar conjunctiva), vessel sludging, intermittent blood flow, and vessel tortuosity were commonly found in or adjacent to locations where the contact lens physically rested on the underlying conjunctival vessels. These results strongly suggest that microvascular abnormalities and remodeling changes occurred as a result of the inadvertent physical interaction of the lenses with either the underlying conjunctival vessels or the surface of the bulbar conjunctiva in contact lens users.
Investigation of critical shear stress with simultaneous measurement of electrical impedance, capacitance and light backscattering
Authors: Lee Byoung-Kwon , Ko Jae-yong , Lim Hyun-jung , Nam Jeong-Hun , Shin Sehyun
Published: December 2019

Recent electrical investigation of hemorheology provided useful information on the kinetics of red blood cell (RBC) aggregation. However, because of the inconsistent results in the electrical measurements, we need to understand the electrical characteristics of RBC aggregation at various flow conditions. In the present study, AC electrical-capacitance (EC) and -impedance (EI) and light backscattering (LB) were simultaneously measured for transient shear-decreasing blood flow in a microchannel. EI, EC and LB signals of RBCs in plasma show similar time-varying curves, both yielding either a peak or a minimal point in the optimal frequency range (10∼500 kHz). Critical shear stress (CSS) determined from EC showed the nearly same results as that determined from LB, with yielding hematocrits-independence and dextran-concentration dependence. However, the high concentration of fibrinogen caused electrical saturation, which resulted in different results of CSS determined from between LB and EC. These results suggest that electrical properties of RBC suspensions should be further examined to replace the optical method of measurement of RBC aggregation.
Prevalence and predictors of slow flow in angiographically normal coronary arteries
Authors: Arbel Yaron , Rind Efrat , Banai Shmuel , Halkin Amir , Berliner Shlomo , Herz Itzhak , Mashav Noa , Thurm Tamar , Keren Gad , Finkelstein Ariel
Published: December 2019

Background: One out of 5 patients undergoing coronary angiography has angiographically normal coronary arteries (ANCA). Some of them have abnormally slow coronary flow (SCF). The prevalence and causes of SCF in these patients are not clear. Methods: We studied 114 consecutive patients with ANCA. Each angiogram was independently evaluated by 2 physicians unaware of all other clinical features of the case. Coronary flow (CF) was graded using the corrected TIMI Frame Count (cTFC) and Coronary Clearance Frame Count (CCFC) methodologies. SCF was defined as a cTFC exceeding the reported normal (mean cTFC + 2 SD) in each of the three major coronary arteries. The association between SCF and various clinical, inflammatory, and metabolic variables was tested using a multivariable analysis model. Results: Thirty-nine (34%) patients had SCF. Inter-individual CF varied substantially among them (range 10–143 frames/sec, mean: 37 ± 22 frames/sec). The intra-individual CF did not vary: CF correlated well in the three major epicardial coronary arteries of a given individual (r = 0.7, p = 0.0001). Multivariable analysis revealed that current smoking was the most significant variable related to SCF (odds ratio = 4.7, p = 0.006, CI 95% 1.6–13.3). The SCF group included significantly more smokers (41% versus 15%, p = 0.002). Conclusions: SCF is a common finding (34%) among patients with angiographically normal coronary arteries. In these patients, slow flow is a systemic phenomenon that involves all three coronary arteries rather than a local event and is associated with current smoking.
Comparative osmotic gradient ektacytometry data on inter-species differences of experimental animals
Authors: Nemeth Norbert , Kiss Ferenc , Klarik Zoltan , Miko Iren
Published: December 2019

It is known that red blood cell deformability may show colorful inter-species differences, influenced by inner viscosity, cell membrane viscosity, morphology and surface-volume ratio of the erythrocytes. It is also well-known that the cell volume is changing depending on the micro-environmental osmolarity. These changes can be well observable using osmotic gradient ektacytometry (osmoscan). Interestingly, there is a lack of base and comparative osmoscan data regarding the experimental/laboratory animal species. In this study mouse, rat, canine and porcine blood samples were analyzed using a LoRRca MaxSis Osmoscan ektacytometer. The highest elongation index values were found in mouse, typically above shear stress of 1 Pa. Some lower values than these were shown in rat and more lower in canine, while the lowest values were detected in porcine, typically above 3–5 Pa. The optimal osmolarity point value, so the measurable maximal EI osmolarity was in a wide range among the species. While the lowest values were detected in canine, the highest ones in porcine and mouse, the rat values were in between. Further analysis and wider comparison of the osmotic gradient ektacytometry may contribute to the better understanding of the erythrocyte micro-rheological properties, their induced changes and inter-species differences.
Effects of ethanol on red blood cell rheological behavior
Authors: Rabai M. , Detterich J.A. , Wenby R.B. , Toth K. , Meiselman H.J.
Published: December 2019

Consumption of red wine is associated with a decreased risk of several cardiovascular diseases (e.g., coronary artery disease, stroke), but unfortunately literature reports regarding ethanol's effects on hemorheological parameters are not concordant. In the present study, red blood cell (RBC) deformability was tested via laser ektacytometry (LORCA, 0.3–30 Pa) using two approaches: 1) addition of ethanol to whole blood at 0.25%–2% followed by incubation and testing in ethanol-free LORCA medium; 2) addition of ethanol to the LORCA medium at 0.25%–6% then testing untreated native RBC in these media. The effects of ethanol on deformability for oxidatively stressed RBC were investigated as were changes of RBC aggregation (Myrenne Aggregometer) for cells in autologous plasma or 3% 70 kDa dextran. Significant dose-related increases of RBC deformability were observed at 0.25% (p < 0.05) and higher concentrations only if ethanol was in the LORCA medium; no changes occurred for cells previously incubated with ethanol then tested in ethanol-free medium. The impaired deformability of cells pre-exposed to oxidative stress was improved only if ethanol was in the LORCA medium. RBC aggregation decreased with concentration at 0.25% and higher for cells in both autologous plasma and dextran 70. Our results indicate that ethanol reversibly improves erythrocyte deformability and irreversibly decreases erythrocyte aggregation; the relevance of these results to the health benefits of moderate wine consumption require further investigation.
Antiplatelet effect of acetylsalicylic acid, metamizole and their combination - in vitro and in vivo comparisons
Authors: Papp J. , Sandor B. , Vamos Z. , Botor D. , Toth A. , Rabai M. , Kenyeres P. , Cseplo P. , Juricskay I. , Mezosi E. , Koller A. , Toth K.
Published: December 2019

BACKGROUND: Acetylsalicylic acid (ASA) plays an important role in the treatment and prevention of cardiovascular diseases. Metamizole (MET) is an analgesic and antipyretic medicine, it is not used as an antiplatelet drug. OBJECTIVES: We aimed to examine the antiplatelet effect of MET and the possible interactions between the drugs. METHODS: In our in vitro investigations different concentrations of ASA and MET solutions were added to blood. To examine the interactions MET and ASA were added together. In our in vivo crossover study intravenous MET, oral ASA or both drugs together were administered. Epinephrine and adenosine-diphosphate induced platelet aggregation was determined by optical aggregometry. RESULTS: Epinephrine-induced aggregation was completely inhibited in all ASA and MET concentrations in vitro. Lower, ineffective concentration of MET prevented the antiplatelet effect of ASA. The inhibition was completely restored when higher concentration of ASA was used or when ASA was added first. Our in vivo study showed that in the MET group rapid onset of inhibition was developed and there was no inhibition after one day. In the ASA group platelet aggregation decreased slowly but still had significant inhibitory effect after 72 hours. Combined therapy showed similar changes to the MET group. CONCLUSION: Antiplatelet effect of MET and ASA did not differ significantly in vitro. The observations may indicate a competitive interaction between the two drugs. The in vivo experiments showed that intravenously administered MET is an effective antiplatelet drug and can be considered as a therapeutic alternative, when ASA cannot be used in oral form.
Mortality of iterated piecewise affine functions over the integers: Decidability and complexity
Authors: Ben-Amram Amir M.
Published: December 2019

In the theory of discrete-time dynamical systems one studies the limiting behaviour of processes defined by iterating a fixed function f over a given space. An important special case involves piecewise affine functions on Rn. Blondel et al., in: Theor. Comput. Sci. 255(1,2) (2001), 687–696, studied the decidability of questions such as global convergence and mortality for such functions with rational coefficients. Mortality means that every trajectory (namely a sequence x0,f(x0),f(f(x0)),…) includes a 0; if the iteration is implemented as a loop while (x≠0) x:=f(x), mortality means that the loop is guaranteed to terminate. Checking the termination of simple loops (under various restrictions of the guard and the update function) is a much-studied topic in automated program analysis.

Blondel et al. proved that the problems are undecidable when the state space is Rn (or Qn), and the dimension n is at least two. From a program analysis (and discrete computability) viewpoint, it is more natural to consider functions over the integers.

This paper establishes (un)decidability results for the integer setting, while strengthening results for the continuous setting. We show that also over integers, undecidability begins at two dimensions. In both settings, we shown Π02 completeness. We further investigate the effect of several restrictions on the iterated functions. Specifically, we consider bounding the size of the partition defining f, and restricting the coefficients of the linear components. In the decidable cases, we give complexity results: The problem is PSPACE-complete for piecewise-affine functions in one dimension; it is polynomial-time for affine functions in any dimension. The undecidability proofs use some variants of the Collatz problem, which may be of independent interest.
The complexity of satisfaction problems in reverse mathematics
Authors: Patey Ludovic
Published: December 2019

Satisfiability problems play a central role in computer science and engineering as a general framework for studying the complexity of various problems. Schaefer proved in 1978 that truth satisfaction of propositional formulas given a language of relations is either NP-complete or tractable. We classify the corresponding satisfying assignment construction problems in the framework of reverse mathematics and show that the principles are either provable over RCA0 or equivalent to WKL0. We formulate also a Ramseyan version of the problems and state a different dichotomy theorem. However, the different classes arising from this classification are not known to be distinct.
Is Cyberbullying Related to Lack of Empathy and Social-Emotional Problems?
Authors: Schultze-Krumbholz Anja , Scheithauer Herbert
Published: December 2019

Examination of the longitudinal relationship between empathy, social-emotional problems and cyberbullying is still rare and the present study is one of very few. The present study assessed whether low scores of affective and cognitive empathy at wave 1 (t1) can predict involvement in cyberbullying five months later (t2). Furthermore, it was examined whether involvement in cyberbullying at t1 predicts psychopathological symptoms and social withdrawal at t2. Participants were 77 7th and 8th grade students from a control group of a pre-/posttest short-term longitudinal evaluation study of a general anti-bullying program (mean aget1 = 12.53 years, SD = 0.68; gendert1 = 54.5% boys, 45.5% girls). Separate quasi-poisson regression analyses were conducted and traditional bullying and victimization were included as control variables. Low scores of affective, but not cognitive, empathy predicted cyberbullying but not cybervictimization at t2. Neither cyberbullying nor cybervictimization predicted social withdrawal or psychopathological symptoms at t2 as assessed in this study. The research hypotheses were only partly supported, however, this study using short-term longitudinal data revealed evidence for the importance of (affective) empathy in cyberbullying perpetration.
When One Is Really Two: Switching from Object to Place Memory in the A-Not-B search task
Authors: Lange-Küttner Chris
Published: December 2019

The A-not-B task is a marker task for infant development where an infant searches for an object being hidden twice, in two consecutive places. In two studies N = 70 infants plus 40 controls were tested in this task using two separate, infant-sized tables. In the first study, the separate tables were joined in front of the infant to form one area. No facilitation effect occurred. In the second study, an air gap was left between tables which facilitated search, but no learning transfer occurred. Results are discussed on the background of object-place binding theory (Treisman, 2006a, b): Initially object-place binding is taking place, which then needs to be dissociated, if the object must be bound to a new, second place. Thus infants need to switch from an object priority to a place priority. An object and place association-dissociation-association binding model (ADA) of spatial learning integrates object-based (object permanence) with space-based accounts of the A-not-B task
Effects of long-duration space flights on characteristics of the vertical gaze fixation reaction1
Authors: Tomilovskaya E.S. , Berger M. , Gerstenbrand F. , Kozlovskaya I.B.
Published: December 2019

The aim of the study was to examine effects of long-duration exposure to weightlessness on characteristics of the vertical gaze fixation reaction (GFR). The subjects were to perform the target acquisition task on visual stimuli that appeared at a distance of 16 deg. up- and down from the primary position in a random order. Experiments were performed before launch, during flight and after landing. Before flight time of gaze fixation reaction did not exceed 650 ms. During space flight (SF) it extended up to 900–1000 ms and more. The velocities of head movement in space decreased, but the velocities of eye counterrotation decreased to a lesser degree. This difference resulted in sharp increase of vertical vestibular ocular reflex (VOR) gain (up to 4.3 values in one of the cosmonauts) during the 1st month of flight; further it decreased reaching the values of 0.5–0.7 on the 5th month of SF. After landing vertical VOR gain increased greatly again. These results in the vertical axis are in agreement with the data of Kozlovskaya et al., which showed in experiments with monkeys that horizontal VOR gain increased together with redundant inadequate responses of vestibular nucleus on vestibular stimulation and that in the course of adaptation to these conditions central nervous system inhibited vestibular input from the motor control system.
The prevalence of vestibular symptoms in migraine or tension-type headache1
Authors: Akdal Gülden , Özge Aynur , Ergör Gül
Published: December 2019

Background: We assessed frequency of vestibular symptoms in Headache Clinic patients over 10 years. Methods: A descriptive study of 5111 consecutive patients with tension-type headache or migraine, analyzed for dizziness/ vertigo accompanying headache and for a lifetime history of motion-sickness, cyclic vomiting, recurrent abdominal pain or atopy. Migraine patients were re-grouped as those with vestibular symptoms (dizziness/vertigo or motion sickness) and those without and their data then re-analyzed. Results: There were 1880 migraine patients and 3231 tension-type headache patients. Significantly more migraine patients than tension-type headache patients experienced vestibular symptoms (p< 0.0001). The migraine with vestibular symptoms group was significantly younger (p< 0.05) had more aura, more phonophobia with migraine attacks (p< 0.0001). Menstruation and reported sleep problems impacted on headaches. While past history of cyclical vomiting, recurrent abdominal pain or atopy was about twice as common in migraine with aura and it was also more common in migraine with vestibular symptoms than migraine without vestibular symptoms. Conclusions: Vestibular symptoms are common in migraine patients. Migraine with vestibular symptoms might constitute a special group, one more likely to have had cyclic vomiting, recurrent abdominal pain or atopy.
Vestibular rehabilitation in acute central vestibulopathy: A randomized controlled trial
Authors: Balci Birgül Donmez , Akdal Gülden , Yaka Erdem , Angin Salih
Published: December 2019

Objective: To investigate the effects of two different rehabilitation programs in acute central vestibulopathy secondary to posterior circulation stroke. Method: A prospective randomized controlled study was conducted on 25 patients with posterior circulation stroke. Patients were instructed in routine balance and mobility exercises during the acute hospitalization period. At discharge, patients were assigned to either a rehabilitation or home exercise group. The home exercise group was instructed to perform the same exercise program provided in the course of hospitalization period. The rehabilitation group was randomized into the visual feedback posturography training or vestibular rehabilitation group. The balance and gait performance were assessed with clinical and objective measurements before and after 6 weeks of training. Results: The balance and gait scores were significantly improved in both rehabilitation groups and in the home exercise group (p< 0.05), but no significant difference was found between the groups in terms of post-treatment values (p> 0.05). Conclusion: The improvements of balance and gait function in rehabilitation groups did not differ from the home exercise group. Rehabilitation programs were equally effective to improve the recovery in acute central vestibulopathy.
A review of synaptic mechanisms of vestibular efferent signaling in turtles: Extrapolation to efferent actions in mammals
Authors: Jordan Paivi M. , Parks Xiaorong Xu , Contini Donatella , Holt J. Chris
Published: December 2019

The vestibular labyrinth of nearly every vertebrate class receives a prominent efferent innervation that originates in the brainstem and ends as bouton terminals on vestibular hair cells and afferents in each end organ. Although the functional significance of this centrifugal pathway is not well understood, it is clear that efferent neurons, when electrically stimulated under experimental conditions, profoundly impact vestibular afferent discharge. Effects range from chiefly excitation in fish and mammalian vestibular afferents to a more heterogeneous mixture of inhibition and/or excitation in amphibians, reptiles, and birds. What accounts for these diverse response properties? Recent cellular and pharmacological characterization of efferent synaptic mechanisms in turtle offers some insight. In the turtle posterior crista, vestibular efferent neurons are predominantly cholinergic and the effects of efferent stimulation on vestibular afferent discharge can be ascribed to three distinct signaling pathways: (1) Hyperpolarization of type II hair cells mediated by α9/α10-nAChRs and SK-potassium channels; (2) Depolarization of bouton and calyx afferents via α4β2*-containing nAChRs; and (3) A slow excitation of calyx afferents attributed to muscarinic AChRs. In this review, we discuss the evidence for these pathways in turtle and speculate on their role in mammalian vestibular efferent actions where synaptic mechanisms are largely unknown.
Neuropharmacological basis of vestibular system disorder treatment
Authors: Soto Enrique , Vega Rosario , Seseña Emmanuel
Published: December 2019

This work reviews the neuropharmacology of the vestibular system, with an emphasis on the mechanism of action of drugs used in the treatment of vestibular disorders. Clinicians are confronted with a rapidly changing field in which advances in the knowledge of ionic channel function and synaptic transmission mechanisms have led to the development of new scientific models for the understanding of vestibular dysfunction and its management. In particular, there have been recent advances in our knowledge of the fundamental mechanisms of vestibular system function and of drug action. In this work, drugs acting on vestibular system have been grouped into two main categories according to their primary mechanisms of action: those with effects on neurotransmitters and neuromodulators dynamics and those that act on voltage-gated ion channels. Particular attention is given in this review to drugs that may provide additional insight into the pathophysiology of vestibular diseases. The critical analysis of the literature reveals that there is a significant lack of information defining the real utility of diverse drugs used in clinical practice. The development of basic studies addressing drug actions at the molecular, cellular and systems level, combined with reliable and well controlled clinical trials, would provide the scientific basis for new strategies for the treatment of vestibular disorders.
New insights into vestibular neuropharmacology: From bench to bedside
Authors: Chabbert Christian
Published: December 2019

Recent epidemiological investigations have highlighted the high prevalence of vestibular dysfunctions in the adult population and its association with aging. Despite a large and unmet medical need, the pharmaceutical options of targeted and efficient drugs to reduce the symptoms associated with vestibular deficits remains largely insufficient.

This special issue of the Journal of Vestibular Research is devoted to the session: New insights on vestibular neuropharmacology: From bench to bedside, that was organized at the 2012 Midwinter Meeting of the Association of Research in Otolaryngology.

This special issue intends 1. to emphasize the current state of the medical need for potent pharmacological treatments of vestibular deficits while highlighting questions regarding the molecular targets, the therapeutic window and the role of pharmacological treatment versus physiotherapy; 2. to give an overview of the fundamental mechanisms of vestibular system function and the mechanism of action of the drugs currently used in the treatment of vestibular disorders and 3. to present recent discoveries in basic research, that may lead to future drug identification to efficiently alleviate the vertigo crisis and protect the vestibule. This theme should target a broad audience ranging from ENT clinicians to scientists, including pharmacologists and pharmacists.
Auditory-pupillary responses in patients with vestibular neuritis
Authors: Kitajima Naoharu , Kobayashi Noriko , Otsuka Koji , Ogawa Yasuo , Inagaki Taro , Ichimura Akihide , Suzuki Mamoru
Published: December 2019

Pupillary dilation in response to sound stimuli is well established and generally represents a startle reflex to sound. We previously reported that auditory-pupillary responses (APRs) persist with bilateral deafness, and that the pathways mediating APRs involve not only the cochlea but also otolith organs, especially the saccule. Here, we evaluated the vestibulo-autonomic responses in vestibular neuritis (VN) by assessing APRs. Twelve young healthy volunteers without a history of hearing and equilibrium problems and 10 VN patients participated. To clarify the relationship between APRs and vestibular function, especially otolith function, we performed caloric and vestibular-evoked myogenic response testing on VN patients. In normal subjects, we examined APRs when delivering sound stimuli to both sides. In VN patients, we examined APRs when delivering stimuli simultaneously to both sides, to the affected side alone, and then to the unaffected side alone. With binaural stimulation, the pupillary index (PI) – the rate of dilation – of VN patients significantly differed from those of normal subjects. Moreover, in VN patients, PIs of the affected sides were significantly larger than those of the unaffected sides. Our study provides evidence that examining APRs may be useful for evaluating vestibulo-autonomic reflexes, especially otolith-autonomic reflexes.
Intravenous promethazine versus lorazepam for the treatment of peripheral vertigo in the emergency department: A double blind, randomized clinical trial of efficacy and safety
Authors: Amini Afshin , Heidari Kamran , Asadollahi Shadi , Habibi Tahereh , Shahrami Ali , Mansouri Behnam , Kariman Hamidreza
Published: December 2019

Background: Vertigo imposes considerable health restrictions with significant impact on the patient's quality of life. The most effective antivertigo agent is undetermined thus far. Objective: This study was performed to assess whether promethazine has superior vertigo reduction compared with lorazepam in ED patients. Methods: In this randomized, double-blind, parallel group trial 184 patients were assigned (1:1 ratio) to receive either promethazine, 25 mg intravenously, or lorazepam, 2 mg intravenously. Primary endpoint was mean change in vertigo intensity at 2 hours measured using visual analog scale (VAS). Secondary endpoints were mean change in nausea score, need for second dose of study medications, and adverse events (AEs). Results: Promethazine was associated with significantly more reduction (46.5 mm) in vertigo than lorazepam (25.7 mm, p< 0.001). Mean change in nausea score 2 hours after drug injection on the VAS was 28.7 mm for promethazine and 22.8 for lorazepam (p=0.002). The most frequently reported AEs were lethargy (14.1% in lorazepam group, 4.3% in promethazine group, p=0.013) and drowsiness (10.8% for promethazine, 2.1% for lorazepam, p=0.017). Conclusion: Our study demonstrated the evidence that promethazine is superior to lorazepam in management of peripheral vertigo and vertigo-related nausea in ED adults.
Typical and atypical benign paroxysmal positional vertigo: Literature review and new theoretical considerations
Authors: Büki Béla , Mandalà Marco , Nuti Daniele
Published: December 2019

Atypical variants of benign paroxysmal positional vertigo (BPPV) are often encountered and frequently confusing. The authors present a hypothetical framework that accounts for all classical patterns of BPPV and several unusual variants such as BPPV without nystagmus, BPPV with downbeat nystagmus and BPPV with paradoxically direction-changing nystagmus. The authors introduce new concepts, such as “ipsicanal switch” and “horizontal short arm canalolithiasis” and suggest that their use may improve diagnosis and treatment in everyday clinical practice. The possible consequences of saccular otoconia detachment are reviewed according to the literature.
Diagnostic criteria for Menière's disease
Authors: Lopez-Escamez Jose A. , Carey John , Chung Won-Ho , Goebel Joel A. , Magnusson Måns , Mandalà Marco , Newman-Toker David E. , Strupp Michael , Suzuki Mamoru , Trabalzini Franco , Bisdorff Alexandre
Published: December 2019

This paper presents diagnostic criteria for Menière's disease jointly formulated by the Classification Committee of the Bárány Society, The Japan Society for Equilibrium Research, the European Academy of Otology and Neurotology (EAONO), the Equilibrium Committee of the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) and the Korean Balance Society. The classification includes two categories: definite Menière's disease and probable Menière's disease. The diagnosis of definite Menière's disease is based on clinical criteria and requires the observation of an episodic vertigo syndrome associated with low- to medium-frequency sensorineural hearing loss and fluctuating aural symptoms (hearing, tinnitus and/or fullness) in the affected ear. Duration of vertigo episodes is limited to a period between 20 minutes and 12 hours. Probable Menière's disease is a broader concept defined by episodic vestibular symptoms (vertigo or dizziness) associated with fluctuating aural symptoms occurring in a period from 20 minutes to 24 hours.
Effects of Long Duration Centrifugation on Head Movements and a Psychomotor Task
Authors: de Graaf Bernd , de Roo A. Julius
Published: December 2019

Previous investigations suggest strong similarities between aftereffects of an 1.5-hour 3 gx centrifuge run (Sickness Induced by Centrifugation; SIC) and the Space Adaptation Syndrome (SAS). Head movements proved to be especially nauseogenic in both cases. Until recently, during SIC experimentation, the performance of head movements was not adequately operationalized, which hampered a statistical evaluation. For this purpose, a test was designed by which head movements in four directions (left, right, up, and down) were provoked and registered, once before and once after a 1-h 3 g centrifuge run. Subjects had to execute these head movements in order to perform well on a psychomotor task. The results indicate that the test described is sensitive in discriminating between subjects who are seriously affected after a long duration centrifugation and those who are not. Because differences in performance were found only on those parts of the task in which head movements were involved, objective evidence is obtained in favour of a vestibular cause in the etiology of SIC.
High-Frequency Tuning Properties of Bullfrog Lagenar Vestibular Afferent Fibers
Authors: Cortopassi K.A. , Lewis E.R.
Published: December 2019

A common property of vertebrate acoustic sensors, including otoconial acoustic sensors in lower vertebrates, is steep slopes on the high- and low-frequency band edges of the amplitude tuning curves. Bullfrog otoconial acoustic fibers are responsive to sound and exquisitely responsive to substrate vibrations in the frequency range from 20 Hz to 300 Hz. The sum of the absolute values of the two band-edge slopes of the amplitude tuning curve of such a fiber typically ranges from 100 dB/decade to 160 dB/decade (sometimes as high as 220 dB/decade), implying typical dynamic order of at least five to eight. We wondered if such steep slopes and the high dynamic order implied by them reflect special adaptations in acoustic sensors or if they are inherent in all lower-vertebrate otoconial sensors excited in this frequency range. To address this question, we examined the amplitude tuning characteristics of afferent nerve fibers from a bullfrog otoconial vestibular sensor in the same frequency range. In this paper, we report observations of tuning for bullfrog lagenar vestibular fibers in the frequency range from 10 Hz to approximately 500 Hz. To make these observations, we stimulated the frog with random dorsoventral motion that exhibited Gaussian amplitude distribution and that was flat in velocity from 10 Hz to 1.0 kHz. For each afferent fiber studied, we used discrete cross-correlation (between stimulus waveform and axon spike train) and discrete Fourier transformation to compute an amplitude tuning curve. In contrast with the amplitude tuning curves from saccular and lagenar acoustic fibers, those from the lagenar vestibular fibers typically had band-edge slopes whose absolute values summed to approximately 20 dB/decade, implying typical dynamic order of one. We conclude that steep band-edge slopes and high dynamic order are indeed special features of acoustic sensors, not shared by vestibular sensors.
Functional Model of Benign Paroxysmal Positional Vertigo Using an Isolated Frog Semicircular Canal
Authors: Suzuki Mamoru , Kadir Abdul , Hayashi Naoki , Takamoto Muneo
Published: December 2019

Bull frogs posterior semicircular canals (psc) were used to simulate the condition of benign paroxysmal positional vertigo (BPPV). The psc was isolated in frog Ringer's solution, and the saccular otoconia were used as a responsible material to stimulate the cupula. When the otoconia were placed on the cupular surface to mimic the condition of cupulolithiasis, the psc ampullary nerve action potentials instantaneously changed according to the direction of the gravity produced by otoconia. When the otoconia were dropped into the canal to mimic the condition of moving otoconia in the canal, the action potentials changed together with the otoconial flow after a latent period. Both cupulolithiasis and moving otoconia are possibly valid mechanisms of BPPV, since they effectively stimulate the cupula. However, moving otoconia with a latent period would better explain clinical features of BPPV.
Early Diazepam Treatment Following Unilateral Labyrinthectomy Does Not Impair Vestibular Compensation of Spontaneous Nystagmus in Guinea Pig*
Authors: Martin Jacelyn , Gilchrist Darrin P.D. , Smith Paul F. , Darlington Cynthia L.
Published: December 2019

Diazepam and other benzodiazepines are sometimes used to alleviate vertigo and dizziness following labyrinthine surgery in humans. While the results of some previous studies have suggested that the administration of diazepam and other CNS depressant drugs following unilateral labyrinthectomy (UL) may impair the vestibular compensation process, the available evidence is unclear. The objective of the present experiment was to examine the effects of multiple injections of a high dose of diazepam (that is, 10 mg/kg ip) 30 min before and following UL (10 h or 10 and 20 h) on the static symptom, spontaneous ocular nystagmus (SN), in guinea pigs. Although diazepam-treated animals exhibited consistently lower average SN frequency compared to vehicle controls, neither SN frequency nor its rate of compensation were significantly different between the 2 groups. The time to complete SN compensation was also similar for the 2 groups, as estimated from the x intercepts derived from a linear regression analysis. These results suggest that even high doses of diazepam before and following UL do not result in an impairment of compensation of SN in guinea pig.
Distribution of Choline Acetyltransferase mRNA in the Efferent Vestibular Neurons of the Chinchilla
Authors: Bridgeman D. , Hoffman L. , Wackym P.A. , Micevych P.E. , Popper P.
Published: December 2019

The distribution of choline acetyltransferase messenger RNA (mRNA) among efferent vestibular neurons in the chinchilla was investigated. mRNA coding for choline acetyltransferase, the enzyme that synthesizes acetylcholine, was used as a marker for the cholinergic system. In order to retrogradely label the efferent vestibular neurons, Fluoro-gold was injected through the oval window into the inner ear of anesthetized young male chinchillas (6 to 12 months old). The animals were anesthetized and perfused through the heart 2 days post injection with 4% paraformaldehyde in phosphate buffer. Retrogradely labeled efferent vestibular neurons were mapped in brainstem sections prior to processing for in situ hybridization histochemistry using radiolabeled ribonucleic acid probes complementary to the 3' end of the choline acetyltransferase mRNA. At the levels of the ascending facial nerve and the genu of the facial nerve, we found that approximately 90% of the Fluoro-gold labeled cells in group E1 contained choline acetyltransferase mRNA. All of the group E2 cells that were labeled with Fluoro-gold were found to be cholinergic (contain choline acetyltransferase mRNA). Finally, 60% of the Fluoro-gold-Iabeled cells in the caudal pontine reticular nucleus contained choline acetyltransferase mRNA.
Effect of Hemilabyrinthectomy on Monoamine Metabolism in the Medial Vestibular Nucleus, Locus Coeruleus, and Other Brainstem Nuclei of Albino and Pigmented Rats
Authors: Cransac H. , Peyrin L. , Farhat F. , Cottet-Emard J.M. , Pequignot J.M. , Reber A.
Published: December 2019

We compared in albino and pigmented rats the early effect of unilateral labyrinthectomy (UL) on the concentrations of monoamines (norepinephrine, dopamine, serotonin) and their respective metabolites—3-methoxy, 4-hydroxyphenylglycol (MHPG), 3,4-dihydroxy-phenylacetic acid (DOPAC), and 5-hydroxyindoleacetic acid (5HIAA)—in medial vestibular nuclei (MVN), locus coeruleus, raphe dorsalis, and cochlear nuclei. The study was conducted 6 hours after UL in both strains, differing by the functional optokinetic responses of their central vestibular neurons and the time-course of their vestibular compensation. The results show that the monoaminergic changes are different in the two rat strains. In the MVN of albino rats, there was a bilateral increase of MHPG and an ipsilateral increase of dopamine suggesting activation of norepinephrine synthesis and metabolism, whereas no such changes were observed in the MVN of pigmented rats. On the other hand, the simultaneous increase of norepinephrine and DOPAC observed in the contralateral locus coeruleus of albino rats suggested enhanced norepinephrine synthesis, whereas in pigmented rats the decreased norepinephrine content found in the ipsilateral locus coeruleus might reflect an earlier strong stimulation of NE release. These biochemical results confirm the relevant role of locus coeruleus noradrenergic innervation in vestibular compensation and also point out the involvement of norepinephrine of the MVN in the early stages of this process. The different strain-related noradrenergic responses observed on the 6th hour suggest that the involvement of central norepinephrine, particularly from locus coeruleus innervation, may be more crucial and more sustained in the albino than in pigmented rats. No serotonin and SHIAA changes were found in either brainstem nuclei of albino rats. In contrast, the increase of the ratio 5HIAA/5HT observed in raphe dorsalis, in ipsilateral locus coeruleus, and in both sides of MVN of pigmented rats suggested that UL induced an extended and enhanced utilization of 5HT in this strain.
Effects of Vestibular Loss on Head Stabilization in Response to Head and Body Perturbations
Authors: Shupert C.L. , Horak F.B.
Published: December 2019

Control of head position during postural responses is important to facilitate both the interpretation of vestibular signals and the stabilization of gaze. In these experiments, we compared head stabilization for two different postural tasks: 1) in response to perturbations at the head, and 2) in response to perturbations induced at the support surface, which perturb both body and head position. To determine whether normal vestibular function is necessary for head stabilization in these two tasks, responses to forward and backward mechanical perturbations of the head and body were compared for 13 normal subjects and 4 patients with profound bilateral vestibular loss (two with vestibular loss in adulthood and two in infancy). Normal subjects showed little neck muscle activity for body perturbations, but large, early activations in both neck extensors and flexors for head perturbations. In contrast, vestibular patients showed excessive neck muscle activation for body perturbations and reduced or absent neck muscle activity for head perturbations. Patients with vestibular loss in adulthood also showed increased head acceleration in response to both head and body perturbations, but patients with vestibular loss in infancy showed more normal head accelerations. For body perturbations, the differences in head acceleration between patients and normals were greater for later head acceleration peaks, indicating poor head control during the execution of the postural response. Trunk angle changes were also higher in the patients for forward body perturbations, indicating that poorer control of trunk position could have contributed to their poorer head stabilization. These results indicate that the vestibular system plays an important role in head and trunk stabilization for both head and body perturbations. However, the more normal head accelerations of the patients with infant vestibular loss also indicate that other mechanisms, possibly involving neck reflexes, can at least partially substitute for the vestibular system to provide head and trunk stabilization.
The Significance of Motion Sickness in the Vestibular System
Authors: Takahashi Masahiro , Ogata Michihiko , Miura Masako
Published: December 2019

In order to clarify the significance of motion sickness in the vestibular system, we compared the findings of experimental motion sickness between different kinds of subjects, some of which were already reported. Subjects were healthy adults, healthy children between the ages of 4 and 15 years, and patients with congenital and acquired labyrinthine loss. They were asked to walk while wearing horizontally and vertically reversing goggles. Equilibrium ataxia as well as motion sickness were evoked by horizontal reversal, but not by vertical reversal in healthy subjects. Kindergarten children exhibited severe ataxia, but little nausea. The frequency of severe ataxia decreased during growth, inversely as the frequency of nausea syndrome increased. Although a patient with acquired loss became severely ataxic, a patient with congenital loss did not show any ataxia at all. The present study suggests that vestibular cues are indispensable to the ego-spatial relationship in the brain, and once the ego–spatial relationship becomes inadequate, discomfort acts as a safety device to brake uncontrollable actions. Then, perception of the outer world may automatically adjust voluntary actions by affecting motor commands. The importance of visual cues for representing an alternative framework may differ between congenital and acquired labyrinthine loss.
Classical Conditioning Using Vestibular Reflexes
Authors: Quinn Kevin J.
Published: December 2019

Adaptation of the vestibulo-ocular reflex (VOR) is one of the principal models for studying motor learning in the mammalian eNS. However, there has been no previous comprehensive attempt to understand the behavioral characteristics of VOR adaptation in terms of traditional psychological learning theory. To accomplish this objective, the effectiveness of vestibular-evoked responses in serving as the conditioned or unconditioned stimulus in classical conditioning paradigms is first reviewed. Then, the various procedures for eliciting VOR adaptation are reviewed from the perspective of their similarity to standard classical conditioning protocols. A systematic analysis of Western and Russian literature yielded a relatively small number of studies that explicitly used vestibular reflexes in classical conditioning paradigms, and they report a wide range in success. Potential explanations for these diverse findings are discussed. A comprehensive categorization of the behavioral parallels between VOR adaptation and classical conditioning is then presented. Viewing VOR adaptation as a form of classical conditioning is a useful heuristic device and leads directly to the description of further behavioral experiments that could throw additional light on general mechanisms for inducing neural plasticity. Such an exercise is of benefit in order to further understand the common framework which might exist between VOR adaptation and other models of motor learning (for example, rabbit eye blink conditioning).
A Link-Segment Model of Upright Human Posture for Analysis of Head-Trunk Coordination
Authors: Nicholas Spero C. , Doxey-Gasway D.D. , Paloski William H.
Published: December 2019

Sensory-motor control of upright human posture may be organized in a top-down fashion such that certain head-trunk coordination strategies are employed to optimize visual and/or vestibular sensory inputs. Previous quantitative models of the biomechanics of human posture control have examined the simple case of ankle sway strategy, in which an inverted pendulum model is used, and the somewhat more complicated case of hip sway strategy, in which multisegment, articulated models are used. While these models can be used to quantify the gross dynamics of posture control, they are not sufficiently detailed to analyze head-trunk coordination strategies that may be crucial to understanding its underlying mechanisms. In this paper, we present a biomechanical model of upright human posture that extends an existing four mass, sagittal plane, link-segment model to a five mass model including an independent head link. The new model was developed to analyze segmental body movements during dynamic posturography experiments in order to study head-trunk coordination strategies and their influence on sensory inputs to balance control. It was designed specifically to analyze data collected on the EquiTest™ (NeuroCom International, Clackamas, OR) computerized dynamic posturography system, where the task of maintaining postural equilibrium may be challenged under conditions in which the visual surround, support surface, or both are in motion. The performance of the model was tested by comparing its estimated ground reaction forces to those measured directly by support surface force transducers. We conclude that this model will be a valuable analytical tool in the search for mechanisms of balance control.