Peripheral vestibular system: Age-related vestibular loss and associated deficits

Given the interdependence of multiple factors in age-related vestibular loss (e.g., balance, vision, cognition), it is important to examine the individual contributions of these factors with ARVL. While the relationship between the vestibular and visual systems has been well studied (Bronstein et al., 2015), little is known about the association of the peripheral vestibular system with neurodegenerative disorders (Cronin et al., 2017). Further, emerging research developments implicate the vestibular system as an opportunity for examining brain function beyond balance, and into other areas, such as cognition and psychological functioning. Additionally, the bidirectional impact of psychological functioning is understudied in ARVL. Recognition of ARVL as part of a multifaceted aging process will help guide the development of integrated interventions for patients who remain at risk for decline. In this review, we will discuss a wide variety of characteristics of the peripheral vestibular system and ARVL, how it relates to neurodegenerative diseases, and correlations between ARVL and balance, vision, cognitive, and psychological dysfunction. We also discuss clinical implications as well as future directions for research, with an emphasis on improving care for patients with ARVL.     

听神经病伴发前庭下神经损害

目的 通过检测13例听神经病患者的前庭诱发的肌源性电位(vestibular evokedmyogenic potentials,VEMPs),了解听神经病患者是否同时伴发前庭下神经损害,探讨前庭下神经损害与听神经病的关系。方法 记录13例听神经病患者VEMPs,观察VEMPs表现形式;分析病程、低频听阈及言语识别率与VEMPs的关系。结果 13例听神经病患者中有7例存在VEMPs异常,占54％。异常的表现形式为VEMPs低振幅和VEMPs不能引出。正常VEMPs与异常VEMPs在低频听力损失、病程和言语识别率3个方面差异无显著性(P>0.05)。结论 部分听神经病患者伴发前庭下神经功能异常,说明两者病变可以同时并存;听神经病患者的病变程度方面与VEMPs无明显直接相关性,说明听神经病与前庭下神经损害两者之间又具有相对独立性。     

听神经病对前庭功能的影响

目的探讨听神经病患者的前庭功能,以了解听神经病患者的平衡能力。方法对32例听神经病患者及正常对照组患者行前庭功能检查,包括眼震电图检查和静态姿势描记图检查,并将2组的结果进行比较。结果听神经病患者的平衡能力减低,眼震电图检查异常者6例(18.75%),姿势描记图检查结果明显异常,睁、闭眼状态下,重心晃动的轨迹长度与晃动速度与正常对照组相比较,差异有显著性意义(P<0.05)。结论在今后的临床工作中,对听神经病患者不妨加行前庭功能检查,以进一步了解其第Ⅷ颅神经的功能状态,尤其是静态姿势描记图,该测试快速、简单,结果客观可靠。     

Tinnitus in central vestibular disorders

A total of100 patients on whom cranio-corpo-graphy and pure tone audiometry was performed is included in the study. The incidence and nature of tinnitus in various central and peripheral dysequilibrium states is analysed. The presence of vestibulo-auditory connection at the central level is confirm ed. It is seen that tinnitus does not bear a topodiagnostic relationship to the site of lesion in central vestibular disorders. Tinnitus in diabetes as a further sub group is analysed. All results are graphically displayed.     

Testing the central vestibular functions: a clinical survey

In vestibular examinations anomalies in the saccade and smooth pursuit tests as well as the fixation suppression after caloric stimulation might indicate central lesions in the vestibular system. Additionally, a high gain in the torsion test is suspicious of cerebellar dysfunction. In this study, 141 patients out of 973 had at least one of these anomalies. For 125 patients we were able to compare the initial findings in the vestibular examination with the final diagnosis by otologists, neurologists and general practitioners. The complaints of 37.6% of the patients with these electronystagmographic (ENG) anomalies appeared to be of central origin. Abnormal saccades, an abnormal smooth pursuit, and an elevated gain in the torsion test were not independently diagnostic for central vestibular disease. The fixation suppression index appeared to be lower for subjects with peripheral vestibular disease. Otologists more often referred their patients to a neurologist if the fixation index was elevated.     

Peripheral vestibular dysfunction in chronic fatigue syndrome

OBJECTIVE: To report left-sided peripheral vestibular failure as the cause of dizziness in a 12-year-old boy diagnosed as having chronic fatigue syndrome (CFS). DESIGN: Retrospective case report with review of literature and discussion. SETTING: Tertiary children's hospital. CONCLUSION: We recommend proper vestibular assessment for CFS patients presenting with dizziness, as effective treatment for peripheral vestibular disorder exists in the form of balance rehabilitation exercises.     

听神经病伴发前庭下神经损害

OBJECTIVE: To investigate if auditory neuropathy have inferior vestibular nerve (IVN) lesion and to explore the relation between AN and the IVN lesion by vestibular evoked myogenic potentials (VEMPs). METHODS: VEMPs were observed in 13 patients with auditory neuropathy. And the relation among the duration, hearing threshold of lower frequency and speech discrimination score with VEMPs were observed. RESULTS: Fifty-four percent patients in auditory neuropathy had abnormal VEMPs. They took the form of lower amplitude and no response. The statistical analysis showed that the abnormality of VEMPs had no correlation with lower frequency hearing loss, the duration and speech discrimination score. CONCLUSIONS: The IVN dysfunction may coexist with auditory neuropathy, having lesion in the IVN. However, there was no significant relation between the severity of AN and VEMPs, which meant that AN and inferior vestibular neuropathy had their independence to some extent.     

Efficacy of electrotactile vestibular substitution in patients with peripheral and central vestibular loss

Vestibular dysfunction of either central or peripheral origin can significantly affect balance, posture, and gait. We conducted a pilot study to test the effectiveness of training with the BrainPort balance device in subjects with a balance dysfunction due to peripheral or central vestibular loss. The BrainPort balance device transmits information about the patient's head position via electrotactile stimulation of the tongue. Head position data is sensed by an accelerometer and displayed on the tongue as a pattern of stimulation. This pattern of stimulation moves forward, backward, and laterally on the tongue in direct response to head movements. Users of the device were trained to use this stimulation to adjust their position in order to maintain their balance. Twenty-eight subjects with peripheral or central vestibular loss were trained with the BrainPort balance device and tested using the following standardized quantitative measurements of the treatment effects: Computerized Dynamic Posturography (CDP) using the Sensory Organization Test (SOT), Dynamic Gait Index (DGI), Activities-specific Balance Confidence Scale (ABC), and Dizziness Handicap Inventory (DHI). All subjects had chronic balance problems and all but one had previously participated in vestibular rehabilitation therapy. The scores on the clinical tests upon entry into the study were compared to their scores following training with the BrainPort balance device. Our results exhibit consistent positive and statistically significant improvements in balance, posture and gait. These results exceed what could normally be achieved in three to five days of traditional balance training alone. Since this was not a controlled study, we are unable to distinguish the degree to which these improvements are attributable to training with the BrainPort balance device versus the balance exercises performed by all subjects as a part of the BrainPort training sessions. Nonetheless, after training with the BrainPort balance device, all subjects demonstrated significant improvements in performance beyond what might be expected from conventional vestibular rehabilitation therapy.     

Possible implication of an efferent neuropathy in vestibular upset

This essay examines two possible mechanisms whereby a neuropathy affecting the efferent vestibular innervation may cause incoordination of vestibular afferent input to the Vestibular Integrating Centres: firstly, by loss of the normal fine control of afferent impulses; secondly, by a disruption of the sodium-potassium pump mechanism that maintains the ionic stability of the inner ear fluids.     

Peripheral vestibular vertigo and functional disorders of the craniovertebral joint

Some vertiginous lesions producing nystagmus (e.g. acute vestibulopathy, benign paroxysmal postural vertigo and Ménière's disease) are well-defined diseases of purely labyrinthine origin. The possible place of a functional disorder of the vertebral joints on their etiology and pathogenesis, has been discussed, but is purely hypothetical. Since the lesion almost always reaches with reduced function of the vestibular apparatus, the course of the disease depends crucially on central compensation of the peripheral disorder of vestibular function. Investigations of the effect of a functional disorder of the vertebral joints on the central compensation of vestibular functional disorders have not been described previously. Our own observations show that a functional disorder of the vertebral joints can crucially impair central compensation of peripheral vestibular vertigo. The pathological mechanism of the impaired compensation is discussed, and diagnostic and therapeutic consequences explained.     

Cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS)

Cerebellar ataxia with neuropathy and bilateral vestibular areflexia syndrome (CANVAS) is a novel ataxic disorder consisting of the triad of cerebellar impairment, bilateral vestibular hypofunction, and a somatosensory deficit. We report the first Japanese case of CANVAS. The patient is a 68-year-old Japanese male. He was referred to our university for further evaluation of progressive gait disturbance and ataxia. He exhibited horizontal gaze-evoked nystagmus and sensory deficit. Nerve conduction studies showed sensory neuronopathy. Magnetic resonance imaging showed the atrophy of vermis but not of the brainstem. The caloric stimulation and video head impulse test (vHIT) showed bilateral vestibulopathy. The visually enhanced vestibulo-ocular reflex (VVOR) was also impaired. In addition to neurological and electrophysiological examinations, simple neuro-otological examinations (i.e., caloric stimulation, vHIT, and VVOR) may reveal more non-Caucasian cases.     

Involvement of peripheral vestibular nerve in individuals with auditory neuropathy

The vestibulocochlear nerve is a sensory nerve that serves the organs of hearing and equilibrium. Neuropathies of the nerve, particularly auditory neuropathy may be caused by primary demyelination or by axonal diseases. In disorders affecting the cochlear nerve, it is probable that the vestibular nerve is involved as well. There are isolated reports of the involvement of the inferior vestibular nerve (using vestibular-evoked myogenic potentials) in individuals with AN. However, there is a dearth of information on the involvement of the superior vestibular nerve and other functions such as optokinetic, saccade and vestibulo-occular reflex. A total of three subjects diagnosed as having auditory neuropathy, underwent an extensive vestibular assessment consisting of clinical tests of stability (Romberg, Fukuda stepping test), administration of dizziness questionnaire developed by Maryland hearing and balance centre, cervical vestibular-evoked myogenic potentials and a standard electronystagmography test battery. In the present study, the entire subject population assessed showed hypofunctional caloric responses and absent VEMPs. Two out of the three subjects were asymptomatic of vestibular dysfunction. On the clinical tests of stability, two subjects showed deviations to the right, while one subject performed normally. Thus, the present study indicates a possible involvement of peripheral vestibular nerve involvement in individuals with auditory neuropathy.     

Peripheral and central yestibular disorders in alcoholics

Summary Vestibular disorders were found in all 33 Japanese men who had been drinking alcohol for over 20 years and who had abstained from alcohol for over 3 months before the tests were done. Six, 12, and 15 patients showed peripheral, central, and combined types of vestibular disorders, respectively. The peripheral disorder occurred in younger alcoholics (under 50 years old) with a drinking history of 20–30 years, and the combined disorder in older patients with a longer drinking history. The vestibular disorders, however, were not observed in any of 16 control non-alcoholics. A follow-up study on seven alcoholics with a 3-year abstinence from alcohol revealed an improvement of vestibular dysfunctions, in particular of peripheral disorders, with an abstinence of over 2 years.     

Changes in postural control parameters after vestibular rehabilitation in patients with central vestibular disorders

OBJECTIVE: The aim of this study was to determine postural responses before and after a vestibular rehabilitation program (VRP) in 14 patients with central vestibular disorders (CVD). MATERIAL AND METHODS: The confidence ellipse (CE) of the center of pressure distribution area and the sway velocity (SV) were the parameters used for the quantitative assessment of postural control (PC). These two parameters were analyzed before and after a VRP for two visual conditions. Behavioral postural responses were studied by means of the time-frequency scalogram using wavelets and the sway frequency content was measured in arbitrary units of energy density. RESULTS: Ten patients showed a significant decrease in the CE and SV after the rehabilitative treatment, thus improving their PC. Seven of these patients were assessed again after a period of 12 +/- 5 months, during which they had not received any physical training. All of them showed increases in the CE and SV, indicating an impairment of PC. CONCLUSIONS: Many CVD patients damage the neural mechanisms involved in retaining the plastic changes in the PC parameters after rehabilitative treatment. Continuation of training may be necessary in order to maintain the improvement in PC obtained with a VRP.     

Electronystagmography finding in children with peripheral and central vestibular disorders

OBJECTIVE: Dizziness and imbalance are uncommon in children, but often alarming for their families: a detailed interview and otoneurological examination are important for reaching a specific diagnosis and treatment. Children with vestibular disorders are thought to be difficult to examine: vestibular tests (caloric test, roto-acceleratory test, electronystagmography, opto-kinetic nystagmus, cranio-corpography and posturography) are used less frequently for children than in adult patients. The aim of the study was to determine whether the results of electronystagmography testing improve an emergency physician's diagnosis of dizziness in children. METHODS: Patients were selected on the basis of the following inclusion criteria: aged between 2 and 12 years and affected with vertiginous symptoms. All patients underwent the following instrumental examinations: blood tests, audiological screening, electronystagmography of spontaneous nystagmus or provoked by vestibular and optical stimulation and electroencephalogram. RESULTS: The results underlines an high incidence of central vertigo (83%): 52% of the children presented a prevailing unidirectional nystagmus at labyrinth stimulation and 48% of the children an asymmetry in the response of nystagmus at optical kinetic stimulation with quality alteration of shocks. CONCLUSIONS: Electronystagmography can register and evaluate the qualitative and quantitative characteristics of the nystagmic response and allow to distinguish between central or peripheric vertigo: different degrees and various combinations of the abnormal responses shown in optokinetic central test were the most characteristic of electronystagmography in patients with vestibular central vertigo.