The molecular,electrophysiological,and structural changes in the vestibular nucleus during vestibular compensation:a narrative review

The vestibular system involves high-level sensory and cognitive processes,such as spatial perception,balance control,visual stability,and emotional control.Vestibular dysfunction can induce vertigo,blurred vision,postural imbalance,walking instability,and spatial discomfort,which causes serious damage to health.It has long been known that after peripheral vestibular lesion,vestibular dysfunction may spontaneously recover.This is known as vestibular compensation.However,at least 20%to 30%of patients with vestibular disorders cannot yield vestibular compensation and remain with vestibular dysfunction for the rest of their lives.The exploration of the biological characteristics and regulatory factors of the loss and reestablishment of vestibular function will establish a new understanding of the mechanism of vestibular compensation and provide new tools and strategies for promoting vestibular rehabilitation.We aim to comprehensively review the mechanism of vestibular compensation and discuss future directions in this field.

Modification of tenascin-R expression following unilateral labyrinthectomy in rats indicates its possible role in neural plasticity of the vestibular neural circuit

We have previously found that unilateral labyrinthectomy is accompanied by modification of hyaluronan and chondroitin sulfate proteoglycan staining in the lateral vestibular nucleus of rats and the time course of subsequent reorganization of extracellular matrix assembly correlates to the restoration of impaired vestibular function. The tenascin-R has repelling effect on pathfinding during axonal growth/regrowth, and thus inhibits neural circuit repair. By using immunohistochemical method, we studied the modification of tenascin-R expression in the superior, medial, lateral, and descending vestibular nuclei of the rat following unilateral labyrin- thectomy. On postoperative day 1, tenascin-R reaction in the perineuronal nets disappeared on the side of labyrinthectomy in the superior, lateral, medial, and rostral part of the descending vestibular nuclei. On survival day 3, the staining intensity of tenascin-R reaction in perineuronal nets recovered on the operated side of the medial vestibular nucleus, whereas it was restored by the time of postoperative day 7 in the superior, lateral and rostral part of the descending vestib- ular nuclei. The staining intensity of tenascin-R reaction remained unchanged in the caudal part of the descending vestibular nucleus bilaterally. Regional differences in the modification of tena- scin-R expression presented here may be associated with different roles of individual vestibular nuclei in the compensatory processes. The decreased expression of the tenascin-R may suggest the extracellular facilitation of plastic modifications in the vestibular neural circuit after lesion of the labyrinthine receptors.

Advantages of Short-term Personalized Vestibular Rehabilitation at Home Guided by Professional Therapist for Treatment of Decompensated Vestibular Vertigo

Objective Patients suffered a lot from decompensated vestibular vertigo.Pharmacotherapy and vestibular rehabilitation training have been proven to be effective in prompting vestibular compensation.Routine rehabilitation training is faced with the challenges of patients’compliance,completion,the average recuperation time and so on.This study is aimed to investigate advantages of short-term personalized vestibular rehabihitation at home guided by professional therapist.Methods A short-term personalized vestibular rehabilitation program(ST-PVR)was designed for patients with decompensated vestibular vertigo in this study.Results Patients experiencing the ST-PVR program showed significant improvement of Self-Rating Anxiety Scale(SAS),Dizziness Handicap Inventory(DHI),Activities-Specific Balance Confidence Scale(ABC)scores by the second follow-up(at 2nd week after treatment,P<0.05).However-improvement in the medication group occurred slightly later,DHI for 1 month and SAS for 2 months after treatment(P<0.05).Also,the improvement in the onset time of unilateral weakness(UW)at 2nd week after treatment in the personalized vestibular rehabilitation(PVR)group was faster than that in the medication group.Conclusion In general,the short-term PVR program showed great advantages by prompting vestibular compensation quickly and putting forward future direction for clinical treatment on decompensated vestibular vertigo.

Lesion-induced changes of brevican expression in the perineuronal net of the superior vestibular nucleus

Damage to the vestibular sense organs evokes static and dynamic deficits in the eye movements,posture and vegetative functions.After a shorter or longer period of time,the vestibular function is partially or completely restored via a series of processes such as modification in the efficacy of synaptic inputs.As the plasticity of adult central nervous system is associated with the alteration of extracellular matrix,including its condensed form,the perineuronal net,we studied the changes of brevican expression in the perineuronal nets of the superior vestibular nucleus after unilateral labyrinth lesion.Our results demonstrated that the unilateral labyrinth lesion and subsequent compensation are accompanied by the changing of brevican staining pattern in the perineuronal nets of superior vestibular nucleus of the rat.The reduction of brevican in the perineuronal nets of superior vestibular nucleus may contribute to the vestibular plasticity by suspending the non-permissive role of brevican in the restoration of perineuronal net assembly.After a transitory decrease,the brevican expression restored to the control level parallel to the partial restoration of impaired vestibular function.The bilateral changing in the brevican expression supports the involvement of commissural vestibular fibers in the vestibular compensation.All experimental procedures were approved by the 'University of Debrecen–Committee of Animal Welfare'(approval No.6/2017/DEMAB) and the 'Scientific Ethics Committee of Animal Experimentation'(approval No.HB/06/éLB/2270-10/2017;approved on June 6,2017).

Evaluation of Vestibular Function in Diagnosis of Vestibular Schwannomas

Vestibular schwannomas(VS)are benign tumors of the vestibular nerve.The common first symptoms are hearing loss and tinnitus,followed by imbalance,vertigo,and facial nerve involvement.The subjective symptoms of VS patients are not consistent with the severity of vestibular lesions and the results of vestibular tests,which often interfere with clinicians’diagnoses.Thus,the main screening and diagnostic methods for VS are audiometry and magnetic resonance imaging(MRI),ignoring the evaluation of vestibular function at the source of pathological lesions.With the development and improvement of vestibular evaluation technology and its wide application in the clinic,modern vestibular examination technology can reflect the severity and frequency of vestibular lesions and compensation from multiple perspectives,providing an objective basis for the diagnosis and treatment of vestibular diseases.In this report,we review the results and characteristics of vestibular tests in VS patients and further clarify the clinical value of vestibular function assessment in the diagnosis and treatment of VS.

Comparison of Pharmacodynamic Property of Two Kinds of Betahistine Drugs

Betahistine drugs are widely used in vestibular compensation process. For theunderstanding of drugs＇ structural feature, two betahistine drugs＇ （betahistine hydrochloride andbetahistine methanesulfonate） structure and vibrational spectra were calculated within densityfunctional theory （DFT） method and comparisons have been made with histamine. The drugs＇interactions with the receptors were revealed by using the molecular docking methods. The resultsshow that the discrepancies of pharmacodynamic property would be resulted from minor molecularstructure difference, and the vibrational spectra can be used for monitoring the drugs＇metabolization. Generally, betahistine drugs have better performance in the docking patterns withreceptors, like stronger interactions, forming more hydrogen bonds with receptors than histamine,and the betahistine methanesulfonate is found out to be the best for body recovery as it did inclinical presentation.