Effect of galvanic vestibular stimulation on stroke patients with lateropulsion / 中国康复理论与实践

ObjectiveTo investigate the effect of galvanic vestibular stimulation on stroke patients with lateropulsion. MethodsFrom February to October, 2023, 30 stroke patients with lateropulsion in the First Affiliated Hospital of Nanjing Medical University were divided into control group (n = 15) and experimental group (n = 15) randomly. The control group received routine rehabilitation and sham galvanic vestibular stimulation, and the experimental group received routine rehabilitation and true galvanic vestibular stimulation, for two weeks. They were assessed with Scale for Contraversive Pushing (SCP), subjective visual vertical (SVV), Line Cancellation Test (LCT), Star Cancellation Test (SCT), Berg Balance Scale (BBS), Holden Functional Ambulation Category (FAC) and Barthel Index (BI) before and after treatment. ResultsAll the indexes improved in both groups after intervention (|t| > 2.461, Z > 3.000, P < 0.05), except the SVV orientation, SVV certainty and SCT in the control group; while the SCP, SVV certainty, LCT and FAC were better in the experimental group than in the control group (|t| > 2.189, Z = -2.862, P < 0.05), and the differences before and after intervention were better in the experimental group than in the control group (|t| > 2.382, P < 0.05), except LCT. SCP was correlated with SVV orientation, SVV certainty, SCT, BBS, BI and FAC (|r| > 0.381, P < 0.05). ConclusionGalvanic vestibular stimulation can improve the lateropulsion, balance, walking function and activities of daily living in stroke patients, which may be related to improvement for spatial cognitive function, especially vertical perception.

Effectiveness of galvanic vestibular evoked myogenic potential for evaluation of Meniere's disease

Abstract Objectives: Although the cause of Meniere's disease (MD) is not fully understood, endolymphatic hydrops is widely believed to be responsible for MD. Previous studies have used Air-Conducted Sound (ACS)-induced Vestibular Evoked Myogenic Potentials (VEMPs) to evaluate otolithic function in patients with MD. However, the use of Galvanic Vestibular Stimulation-VEMPs (GVS-VEMPs) with other vestibular tests in MD has been rare. This study aimed to explore the application of galvanic VEMPs in assessing MD. Methods: Normal individuals and patients with unilateral definite MD were included in this retrospective study. All participants underwent pure tone audiometry. Ocular and cervical VEMPs induced by GVS, and ACS were recorded. The characteristic parameters of VEMPs (n1 latency, p1 latency, amplitude, and AR) were analyzed. Results: The provocation rates of GVS-VEMPs did not differ between MD patients and control individuals. Compared with ACS, GVS could evoke potentials with longer latencies. MD patients presented GVS-VEMPs with lower amplitudes and ACS-cVEMP with shorter latencies and had a higher response rate in GVS-oVEMP. However, no differences or correlations were found in the characteristic parameters of GVS-VEMPs among the different stages of MD. Conclusions: GVS is as effective as ACS for inducing VEMP, and GVS-VEMP recording can detect retrolabyrinthine degeneration in MD. Further research is needed to assess the utility of GVS-VEMP in the evaluation of MD severity. Level of evidence: Level 4.

Anatomía, fisiología y rol clínico de la corteza vestibular / Anatomy, physiology and clinical role of the vestibular cortex

El sistema vestibular, mediante sus órganos periféricos, nos permite procesar correctamente los cambios de aceleración angular de la cabeza y lineal del cuerpo y así permitirnos una correcta orientación en el espacio. Esta información sensorial es dirigida hacia los núcleos vestibulares y desde aquí se comunica con los núcleos óculo-motores y estructuras del tálamo a través de tractos ascendentes del tronco encefálico. Posteriormente la información se dirige hacia centros subcorticales y corticales de naturaleza eminentemente multisensorial. La naturaleza y función de estas estructuras es controversial. En esta revisión se abordan los principales conceptos y descubrimientos a nivel de investigación básica y clínica del procesamiento cortical generado por estimulación de tipo vestibular.

The vestibular system, thanks to its peripheral organs, allows us to properly process the angular head movements and linear acceleration in order to give us a proper orientation in space. The information from these sensory inputs is routed to the vestibular nuclei and thence ascending tracts of the brainstem, which communicate with the oculomotor nuclei of the thalamus and structures. Then the information goes to subcortical and cortical centers, which are eminently multisensory nature. The nature and function of these structures are controversial. In this review the main concepts and discoveries at the level of basic and clinical research generated cortical processing of vestibular stimulation are addressed.

The Linear Transmission of the Vestibular Neural Information by Galvanic Vestibular Stimulation / 대한평형의학회지

OBJECTIVE: Growing hypotheses indicate the galvanic vestibular stimulation (GVS) as an alternative method to manage the symptoms of parkinson's disease (PD). GVS is easy and safe for use, and non-invasive. However, it is elusive how the neural information caused by GVS is transmitted in the central nervous system and relieves PD symptoms. To answer this question, we investigated the transmission of neural information by GVS in the central vestibular system, focused on vestibular nucleus (VN). METHODS: Twenty guinea pigs were used for this study for the extracellular neuronal recordings in the VN. The neuronal responses to rotation and GVS were analyzed by curve-fitting, and the numerical responding features, amplitudes and baselines, were computed. The effects of stimuli were examined by comparing these features. RESULTS: Twenty six vestibular neurons (15 regular and 11 irregular neurons) were recorded. Comparing the difference of baselines, we found the neural information was linearly transmitted with a reduced sensitivity (0.75). The linearity in the neural transmission was stronger in the neuronal groups with regular (correlation coefficient [Cor. Coef.]=0.91) and low sensitive units (Cor. Coef.=0.93), compared with those with irregular (Cor. Coef.=0.86) and high-sensitive neurons (Cor. Coef.=0.77). CONCLUSION: The neural information by GVS was linearly transmitted no matter what the neuronal characteristics were.

Can Postural Instability Respond to Galvanic Vestibular Stimulation in Patients with Parkinson's Disease?

OBJECTIVE: Galvanic vestibular stimulation (GVS) activates the vestibular afferents, and these changes in vestibular input exert a strong influence on the subject's posture or standing balance. In patients with Parkinson's disease (PD), vestibular dysfunction might contribute to postural instability and gait disorders. METHODS: Current intensity was increased to 0.7 mA, and the current was applied to the patients for 20 minutes. To perform a sham stimulation, the current intensity was increased as described and then decreased to 0 mA over the course of 10 seconds. The patient's status was recorded continuously for 20 minutes with the patient in the supine position. RESULTS: Three out of 5 patients diagnosed with PD with postural instability and/or abnormal axial posture showed a reduction in postural instability after GVS. The score for item 12 of the revised Unified Parkinson's Disease Rating Scale part 3 was decreased in these patients. CONCLUSIONS: The mechanism of postural instability is complex and not completely understood. In 2 out of the 5 patients, postural instability was not changed in response to GVS. Nonetheless, the GVS-induced change in postural instability for 3 patients in our study suggests that GVS might be a therapeutic option for postural instability.

Galvanic vestibular stimulation: a novel modulatory countermeasure for vestibular-associated movement disorders / Estimulacao galvanica vestibular para corrigir transtornos neurologicos associados a disfuncao vestibular

Motion sickness or kinetosis is the result of the abnormal neural output originated by visual, proprioceptive and vestibular mismatch, which reverses once the dysfunctional sensory information becomes coherent. The space adaptation syndrome or space sickness relates to motion sickness; it is considered to be due to yaw, pith, and roll coordinates mismatch. Several behavioural and pharmacological measures have been proposed to control these vestibular-associated movement disorders with no success. Galvanic vestibular stimulation has the potential of up-regulating disturbed sensory-motor mismatch originated by kinetosis and space sickness by modulating the GABA-related ion channels neural transmission in the inner ear. It improves the signal-to-noise ratio of the afferent proprioceptive volleys, which would ultimately modulate the motor output restoring the disordered gait, balance and human locomotion due to kinetosis, as well as the spatial disorientation generated by gravity transition.

A cinetose ou doença do movimento resulta de uma resposta neural anormal originada do desequilíbrio entre estímulos visuais, proprioceptivos e vestibulares, que melhora quando esse desequilíbrio é corrigido. A síndrome de adaptação espacial ou doença do espaço está relacionada à doença do movimento e é desencadeada por mudanças bruscas de direção, inclinação e rotação da cabeça. Têm sido propostas várias medidas comportamentais e farmacológicas para controlar esses transtornos do movimento associados com o sistema vestibular, mas sem sucesso. A estimulação galvânica vestibular pode regular o desequilíbrio sensitivo-motor causado pela cinetose e pela doença do espaço modulando os canais iônicos GABA, relacionados à transmissão de impulsos nervosos no ouvido interno. Essa estimulação melhora a relação sinal-ruído dos impulsos proprioceptivos que acabam modulando a resposta motora, restabelecendo o equilíbrio e a marcha, recuperando a desorientação espacial causada pelos diversos gradientes de gravidade.

Contribution of Galvanic Vestibular Stimulation for the Diagnosis of HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis

BACKGROUND AND PURPOSE: Galvanic vestibular stimulation (GVS) is a low-cost and safe examination for testing the vestibulospinal pathway. Human T-lymphotropic virus 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a slowly progressive disease that affects the vestibulospinal tract early in its course. This study compared the electromyographic (EMG) responses triggered by GVS of asymptomatic HTLV-1-infected subjects and subjects with HAM/TSP. METHODS: Bipolar galvanic stimuli (400 ms and 2 mA) were applied to the mastoid processes of 39 subjects (n=120 stimulations per subject, with 60 from each lower limb). Both the short latency (SL) and medium latency (ML) components of the EMG response were recorded from the soleus muscles of 13 healthy, HTLV-1-negative adults (56+/-5 years, mean+/-SD), and 26 individuals infected with HTLV-1, of whom 13 were asymptomatic (56+/-8 years) and 13 had HAM/TSP (60+/-6 years). RESULTS: The SL and ML EMG components were 55+/-4 and 112+/-10 ms, respectively, in the group of healthy subjects, 61+/-6 and 112+/-10 ms and in the HTLV-1-asymptomatic group, and 67+/-8 and 130+/-3 ms in the HAM/TSP group (p=0.001). The SL component was delayed in 4/13 (31%) of the examinations in the HTLV-1-asymptomatic group, while the ML component was normal in all of them. In the HAM/TSP group, the most common alteration was the absence of waves. CONCLUSIONS: A pattern of abnormal vestibular-evoked EMG responses was found in HTLV-1-neurological disease, ranging from delayed latency among asymptomatic carriers to the absence of a response in HAM/TSP. GVS may contribute to the early diagnosis and monitoring of nontraumatic myelopathies.

Application of Force Sensitive Resistors on Evaluation of Vestibulospinal Reflex Induced by Galvanic Stimulation / 대한평형의학회지

BACKGROUND AND OBJECTIVES: Force sensitive resistors (FSR) were used to measure the body sway to galvanic vestibular stimulation (GVS), and compared with the response obtained from force platform in normal subjects. MATERIALS AND METHODS: Bipolar galvanic stimulation was applied to the bilateral mastoid process with intensity of 0.5-1.5 mA and duration of 1 sec in 3 different head positions of forward, rightward, and leftward. RESULTS: Elevation of anterior pressure curve and depression of posterior pressure curve resulting from forward body sway were recorded in both feet by FSR. Forward body sway induced forward deviation of the center of pressure in force platform. Elevation of pressure curve in left foot and depression of the curve in right foot resulting from leftward body sway were recorded by FSR. Leftward body sway induced left deviation of the center of pressure in force platform. Orientation of the body sway induced by GVS was directed towards the anode side in the head facing forwards. Leftward and backward body sway resulting from cathodal stimulation on left mastoid process in leftward rotation of the head position and leftward and forward body sway resulting from cathodal stimulation on left mastoid process in rightward rotation of the head position were recorded by both FSR and force platform. Reaction time of GVS did not show any significant difference between FSR and force platform. CONCLUSION: These results indicate that FSR could be used to evaluate the vestibulospinal reflex to GVS.