Galvanic vestibular stimulation in improving balance in an individual with Parkinson's disease totally dependent for activities of daily living: A case reportABSTRACT
This report describes the immediate and late effects of galvanic vestibular stimulation (GVS) on postural instability in a 75-year-old man with Parkinson's disease (PD) and dementia, who was totally dependent for basic activities of daily living. Postural instability was assessed using the Berg Balance Scale (BBS) and the Timed Up and Go Test (TUG). Analytical measures were taken before, immediately after, and 12 months after the intervention, designated pre-GVS, post-GVS, and post-12m-GVS, respectively. GVS was applied once a week for 8 consecutive weeks, using alternating currents ranging from 1 mA to 3.5 mA. The stimulation duration was 11 minutes in the first week, 18 minutes in the second week, and 30 minutes from the third to the eighth week. TUG values were 26 seconds (pre-GVS), 15 seconds (post-GVS), and 29 seconds (post-12m-GVS). BBS scores were 4 points (pre-GVS), 16 points (post-GVS), and 10 points (post-12m-GVS). Therefore, his postural instability improved, but the effects were not maintained after 12 months.
Keywords:
Parkinson Disease; Dementia; Postural Balance; Electric Stimulation Therapy; Vestibular System
RESUMO
Descreveram-se os efeitos imediatos e tardios da intervenção Estimulação Vestibular Galvânica (EVG) na instabilidade postural de um homem, 75 anos, com doença de Parkinson (DP), demência e dependência total para atividades de vida diária básicas. A instabilidade postural foi avaliada por meio da Escala de Equilíbrio de Berg (EEB) e pelo Timed Up and Go Test (TUG). As medidas de análise foram feitas antes, logo após e doze meses após a intervenção, denominados Pré-EVG, Pós-EVG e após12m-EVG, respectivamente. A EVG foi aplicada uma vez por semana por oito semanas consecutivas. Utilizou-se corrente do tipo alternada com intensidade variando de 1mA a 3,5mA. A duração do estímulo foi de 11 minutos na 1ª semana, 18 minutos na 2ª semana e, da 3ª à 8ª semana, foi de 30 minutos. Para o TUG, no momento Pré-EVG o tempo de execução foi de 26 segundos, no Pós-EVG foi de 15 segundos e Após-12m-EVG foi de 29 segundos. Para a EEB, o Pré-EVG foi de 4 pontos, o Pós-EVG foi de 16 pontos e Após12m-EVG foi de 10 pontos. Assim, percebe-se que houve melhora da instabilidade postural; no entanto, os efeitos não se mantiveram após 12 meses.
Descritores:
Doença de Parkinson; Demência; Equilíbrio Postural; Terapia por Estimulação Elétrica; Sistema Vestibular
INTRODUCTION
The pathophysiology of Parkinson's Disease (PD) is related to the death of dopaminergic neurons in the substantia nigra and the accumulation of the protein alpha-synuclein in the brainstem and cortex1. Its clinical phase includes motor symptoms of bradykinesia, rigidity, and tremor, occurring asymmetrically between the limbs, and persisting during the progression of the disease2. Postural instability is a motor symptom that appears as the disease progresses and is associated with damage to the peripheral and central vestibular system3.
The Hoehn and Yahr Scale classifies PD into five stages based on the person's ability: I) presence of unilateral mild symptoms, without impact on activities of daily living (ADLs); II) more intense bilateral symptoms, but still without impairment in ADLs; III) bradykinesia and instability impair ADLs, and falls become common; IV) intense instability; the patient cannot stand alone, requires assistance to walk, and becomes dependent; and V) intense rigidity and instability; the patient cannot stand and becomes bedridden4.
Defining the advanced stage of PD is important to ensure treatment adjustments and enable a better quality of life. Deep brain stimulation (DBS) is a treatment option for this stage; however, it is an invasive strategy with risks of complications, such as intracranial hemorrhage and worsening of behavioral symptoms5. Moreover, its exclusion criteria include cognitive impairment, commonly present in the advanced phase, limiting the indication of this type of treatment for this population6. Medications may also have therapeutic limitations, since chronic use of dopaminergic active compounds can cause motor fluctuations and dyskinesia as a side effect2,7. This context has motivated studies on neuromodulation through electrical stimulation.
Galvanic vestibular stimulation (GVS) is a non-invasive neuromodulation method that uses a low-intensity electrical current (up to 5 mA) to induce the release of neurotransmitters in the neural network associated with body balance and related regions8. Thus, GVS can excite the vestibular nerve, the vestibular nuclei, and the cortical areas related to vestibular information processing, improving body balance2,7-9.
GVS is administered through surface electrodes attached to the mastoid processes. The current has an active pole (anode) and an inhibitory pole (cathode) that regulate neural activity. GVS is an easy-to-use, safe, and low-cost method. Its contraindication is limited to the presence of implanted electronic devices, such as pacemakers and cochlear implants.
Studies that used GVS to improve balance found benefits for treating central and peripheral causes of postural instability10. When applied to PD patients, GVS improved postural instability, gait, and posture, making it a promising therapy for their postural rehabilitation2,7,11. This effect results from the ability of the galvanic stimulation to activate the vestibular afferent and efferent system, promoting vestibular compensation8,11,12. This neuroplasticity process allows for improved postural control through vestibular adaptation, which restructures the vestibulospinal reflex. GVS can also stimulate replacement when the remaining peripheral vestibular sensors are insufficient.
The benefits and feasibility of GVS treatment for postural instability in PD have been the subject of research by many scholars. However, the literature questions whether the progression of PD can impact the benefits of treatment13.
Therefore, this study aimed to describe the immediate and late effects of GVS in a PD patient who was totally dependent for basic ADLs, since the literature is scarce in studies investigating the effects of GVS in individuals with advanced PD.
CASE PRESENTATION
The study was approved by the Research Ethics Committee of the Universidade Federal de Minas Gerais and the Hospital Santa Casa de Misericórdia de Belo Horizonte, MG, Brazil, (4.165.733 and 28850619.9.3001.5138, respectively). The patient's guardian agreed to his participation by signing an informed consent form.
The study was carried out in accordance with the Declaration of Helsinki and Resolution 466/2012 of the National Health Council (Ministry of Health, Brazil).
This is a case report of an individual diagnosed with PD and dementia, totally dependent for basic ADLs. Balance assessments were performed before, immediately after, and 12 months after the GVS protocol.
A 75-year-old man diagnosed with PD and dementia was evaluated for postural instability. He has been followed at a Neurology Outpatient Clinic specializing in Movement Disorders in his hometown since his PD diagnosis 15 years before. He is currently at stage 4 on the Hoehn and Yahr Scale - severe disability, according to the authors.
The study was conducted in two phases: Phase A - encompassing the first and second assessments, before and after the GVS protocol, respectively. At this time, the patient was taking Donezepil, Quetiapine, Mirtazapine, Levodopa, and Amantadine. At Phase B, 12 months after the intervention, the participant was taking Donezepil, Quetiapine, Mirtazapine, Safinamide, Prolopa, and Mantidan (amantadine hydrochloride). Levodopa was switched to Prolopa, and Mantidan and Safinamide were added due to worsening motor symptoms of bradykinesia and rigidity.
Assessment
Postural instability was assessed at three time points: before GVS (pre-GVS), immediately after the GVS treatment protocol (post-GVS), and 12 months after GVS treatment (post-12m-GVS), using the Berg Balance Scale (BBS) and the Timed Up and Go Test (TUG), which are validated for assessing functional balance and fall risk14,15. At all time points, the BBS was administered first, followed by the TUG. The test lasted 30 minutes, and each assessment was performed by a different researcher who was blinded to the previous result.
The study participant began GVS treatment after completing physical therapy, which had a limited prognosis.
The BBS has 14 items that assess ADLs. Each item has a 5-point ordinal scale ranging from 0 (the individual is unable to perform the task) to 4 (the individual performs the task independently)14. Thus, the higher the score, the better the performance, and the lower the score, the greater the risk of falling.
The BBS has been validated for PD patients and is recommended in the literature for evaluating pharmacological and non-pharmacological interventions in PD, as it correlates with disease duration, stage, and functioning16. The BBS also correlates with the Hoehn and Yahr Scale16.
The evaluator conducted the BBS in a large room, providing instructions for each task, and remaining with the participant throughout the procedure. The score for each activity was assigned according to the instructions provided by the scale's authors.
The TUG corresponds to the time in seconds it takes an individual to rise from a chair, walk 3 meters, turn around, and return to it15. Task duration of up to 19 seconds suggests independence for ADLs, between 20 and 29 seconds suggests difficulty for ADLs, and equal to or greater than 30 seconds suggests total dependence for ADLs15. The task was performed in a wide hallway with a rigid plastic chair at one end. The study subject was instructed to stand up from the chair, walk to the marking on the floor, turn around, and walk back to the chair. The time to complete this task was measured in seconds after the "go" command.
GVS intervention
The GVS rehabilitation protocol was initiated immediately after the first assessment, using the Evokadus - GVS (CONTRONIC®) device.
The GVS protocol used in this study was based on a previous study that evaluated quality of life and voluntary attention in individuals with PD17. Thus, the GVS parameters were a pulse duration of 400 milliseconds (ms); an interpulse interval of 4000 ms; a random stimulation; a variable stimulation current per session (Table 1); a buzzer volume of 50%; alternating current polarity; and a pulsed current mode.
Eight consecutive sessions were conducted (one per week), with an average duration of 30 minutes. In each session, the participant sat in a comfortable chair, barefoot, without metal or electronic objects in their pockets. Both mastoid processes were cleaned with saline-moistened gauze. Self-adhesive electrodes were then attached to the cleaned area. The individual was instructed to keep his eyes closed throughout the stimulation.
Figure 1 shows the position of the patient, the electrodes, and the equipment used to perform the stimulation.
RESULTS
Table 2 shows the results of the tasks that investigated postural instability at the three evaluation time points (pre-GVS, post-GVS, and post-12m-GVS). The values decreased from pre-GVS to post-GVS but increased from post-GVS to post-12m-GVS.
DISCUSSION
Postural instability is common in the progression of PD due to changes in the central nervous system in areas related to body balance. In advanced PD, postural instability can be exacerbated by muscle stiffness resulting from proprioceptive changes, altered vestibulospinal reflexes, and adverse effects of dopaminergic medications.
The TUG provides information about the risk of falling when standing, walking, turning, and sitting15. Healthy older adults without risk of falling score up to 12 seconds. Scores between 12 and 19 seconds suggest a low probability of falling or a sporadic occurrence. Scores above 20 seconds indicate a high risk of falling and correspond to older adults with severe movement limitations and restrictions in ADLs15.
The data obtained in this study corroborate the findings in the literature, as the individual had a TUG score of 26 seconds and was dependent on his caregiver for all movements, including standing, in the initial phase (without intervention). After the GVS intervention, the score was reduced to 15 seconds, and the need for assistance decreased, although still present. It is noteworthy that the need for assistance at both time points was primarily due to stiffness.
However, 12 months after GVS, the walking time increased by 14 seconds compared to the post-GVS, totaling 29 seconds. At this point, the need for assistance to perform the task was also greater. After 12 months, the stiffness was more pronounced, and the patient had a more hunched posture, which also impaired mobility. Thus, GVS improved gait, but the results were not maintained after 12 months.
The BBS provides information on the risk of falls during movements necessary for ADLs. The literature indicates that the BBS score correlates with the stage of PD, classified using the Hoehn and Yahr Scale16. This is consistent with the findings of this study, given that the subject is classified as level IV (severe disability) according to the Hoehn and Yahr Scale and presented a score of four on the BBS before treatment, demonstrating great difficulty with ADLs, which were performed only with assistance.
Regarding the intervention, the study subject was at high risk of falling for all movements assessed pre-GVS. The performance of these activities improved immediately after the intervention (post-GVS), although he was still dependent and at risk of falling (pre = 4 points; post = 16 points). The total score 12 months after GVS decreased by 6 points compared to post-GVS, totaling 10 points at the post-12m-GVS. Nonetheless, it was still higher than the pre-GVS BBS score (4 points). Given the results, it can be inferred that GVS improved ADL performance, as demonstrated by the change in scores between pre-GVS and post-GVS. On the other hand, some of these effects were lost 12 months after treatment, as demonstrated by the comparison between post-GVS and post-12m-GVS.
Other studies have reported improvement in postural instability and gait after GVS intervention in individuals with PD11,18. This effect occurs due to the neuromodulation that GVS performs on the vestibular nerve, the vestibular nuclei, and their outputs (the basal ganglia, limbic system, cerebellar vermis, and other regions). The modulation performed on the parietoinsular cortex, the area responsible for most vestibular processing, stands out, culminating in visuospatial improvement, essential for postural control18. No studies evaluating the long-term effects of GVS in individuals with PD were found.
Thus, the descriptive analysis of the results suggests a trend toward improvement in postural instability after GVS application in individuals with PD totally dependent for basic DLs. However, disease progression, as observed by worsening symptoms of rigidity and bradykinesia reported by family members and observed in the participant, tends to minimize these effects.
This study advances the potential for improving postural instability in individuals with PD totally dependent for basic ADLs, whose prognosis is poor with conventional rehabilitation treatments. It also suggests that GVS treatment should be continuous, as the effects appear to diminish over time. It is also believed that the benefits of treatment will improve quality of life by reducing limitations and the risk of falls, which may impact the individual's physical, psycho-emotional, and social well-being.
Although we present an innovative treatment option, the study has limitations for being a case study. Therefore, studies with larger samples and more robust analyses are recommended to confirm the results. We also suggest studies combining GVS with conventional vestibular rehabilitation to assess whether it could enhance and maintain the effects of GVS in the long term.
FINAL CONSIDERATIONS
GVS reduced postural instability and the risk of falls in an individual with PD totally dependent for basic ADLs. However, the effects do not appear to last over time. Given that therapeutic strategies for these cases are limited, GVS may be a continuous, non-invasive, and low-cost treatment option for individuals presented with advanced PD.
ACKNOWLEDGMENT
Gratitude is extended to the Dean’s office for research (PRPq) of the Universidade Federal de Minas Gerais for the grant to develop the research and publish this article.
REFERENCES
-
1 Henderson MX, Trojanowski JQ, Lee VMY. a-Synuclein pathology in Parkinson's disease and related a-synucleinopathies. Neurosci Lett. 2019;709:134316. https://doi.org/10.1016/j.neulet.2019.134316 PMID:31170426.
» https://doi.org/10.1016/j.neulet.2019.134316 -
2 Kataoka H, Okada Y, Kiriyama T, Kita Y, Nakamura J, Shomoto K et al. Effect of galvanic vestibular stimulation on axial symptoms in Parkinson's disease. J Cent Nerv Syst Dis. 2022;14:1-5. https://doi.org/10.1177/11795735221081 PMID: 35237093.
» https://doi.org/10.1177/11795735221081 -
3 Smith PF. Vestibular functions and Parkinson's disease. Front Neurol. 2018;9:1085. https://doi.org/10.3389/fneur.2018.01085 PMID: 30619045.
» https://doi.org/10.3389/fneur.2018.01085 -
4 Hoehn MM, Yahr MD. Parkinsonism: Onset, progression, and mortality. Neurology. 1967;17(5):427-42. https://doi.org/10.1212/WNL.17.5.427 PMID: 6067254.
» https://doi.org/10.1212/WNL.17.5.427 -
5 Krüger R, Klucken J, Weiss D, Tönges L, Kolber P, Unterecker S et al. Classification of advanced stages of Parkinson's disease: Translation into stratified treatments. J Neural Transm. 2017;124:1015-27. https://doi.org/10.1007/s00702-017-1707-x PMID: 28342083.
» https://doi.org/10.1007/s00702-017-1707-x -
6 França C, Carra RB, Diniz JM, Munhoz RP, Cury RG. Deep brain stimulation in Parkinson's disease: State of the art and future perspectives. Arq Neuropsiquiatr. 2022;80(5 Suppl 1):105-15. https://doi.org/10.1590/0004-282X-ANP-2022-S133 PMID: 35976323.
» https://doi.org/10.1590/0004-282X-ANP-2022-S133 -
7 Samoudi G, Jivegard M, Mulavara AP, Bergquist F. Effects of stochastic vestibular galvanic stimulation and L-DOPA on balance and motor symptoms in patients with Parkinson's disease. Brain Stimul. 2015;8(3):474-80. https://doi.org/10.1016/j.brs.2014.11.019 PMID: 25573070.
» https://doi.org/10.1016/j.brs.2014.11.019 -
8 Curthoys IS, MacDougall HG. What galvanic vestibular stimulation actually activates. Front Neurol. 2012;3:117. https://doi.org/10.3389/fneur.2012.00117 PMID: 22833733.
» https://doi.org/10.3389/fneur.2012.00117 -
9 Tohyama T, Kondo K, Otaka Y. Effects of galvanic vestibular stimulation on visual verticality and standing posture differ based on the polarity of the stimulation and hemispheric lesion side in patients with stroke. Front Neurol. 2021;12:768663. https://doi.org/10.3389/fneur.2021.768663 PMID: 34858316.
» https://doi.org/10.3389/fneur.2021.768663 -
10 Ceylan DS, Atas A, Kaya M. The effect of galvanic vestibular stimulation in the rehabilitation of patients with vestibular disorders. ORL J Otorhinolaryngol Relat Spec. 2021;83(1):25-34. https://doi.org/10.1159/000509971 PMID: 32992316.
» https://doi.org/10.1159/000509971 -
11 Kataoka H, Okada Y, Kiriyama T, Kita Y, Nakamura J, Morioka S et al. Can postural instability respond to galvanic vestibular stimulation in patients with Parkinson's disease? J Mov Disord. 2016;9(1):40-3. https://doi.org/10.14802/jmd.15030 PMID: 26648182.
» https://doi.org/10.14802/jmd.15030 -
12 MacDougall HG, Moore ST, Curthoys IS, Black FO. Modeling postural instability with galvanic vestibular stimulation. Exp Brain Res. 2006;172(2):208-20. https://doi.org/10.1007/s00221-005-0329-y PMID: 16432695.
» https://doi.org/10.1007/s00221-005-0329-y -
13 Khoshnam M, Häner DMC, Kuatsjah E, Zhang X, Menon C. Effects of galvanic vestibular stimulation on upper and lower extremities motor symptoms in Parkinson's disease. Front Neurosci. 2018;12:633. https://doi.org/10.3389/fnins.2018.00633 PMID: 30254564.
» https://doi.org/10.3389/fnins.2018.00633 -
14 Nackachima MA, Souza ML, Scheicher ME. Determination of reference values for the Berg Balance Scale and Gait Speed in institutionalized elderly. Rev Kairos Gerontol. 2020;23(3):241-52. https://doi.org/10.23925/2176-901X.2020v23i3p241-252
» https://doi.org/10.23925/2176-901X.2020v23i3p241-252 -
15 Bretan O, Elias Silva J, Ribeiro OR, Eduardo Corrente J. Risk of falling among elderly persons living in the community: Assessment by the Timed Up and Go test. Braz J Otorhinolaryngol. 2013;79(1):18-21. https://doi.org/10.5935/1808-8694.20130004 PMID: 23503902.
» https://doi.org/10.5935/1808-8694.20130004 -
16 Scalzo PL, Nova IC, Perracini MR, Sacramento DRC, Cardoso F, Ferraz HB et al. Validation of the Brazilian version of the Berg Balance Scale for patients with Parkinson's disease. 2009;67(3-B):831-5. Arq Neuropsiquiatr. https://doi.org/10.1590/s0004-282x2009000500010 PMID: 19838513.
» https://doi.org/10.1590/s0004-282x2009000500010 -
17 Oliveira RCCD, Labanca L, Meireles PGZ, Diniz ML, Pires APB de Á, Barroso JC et al. Galvanic vestibular stimulation to improve postural instability, voluntary attention, and quality of life in Parkinson's disease patients. Rev. CEFAC. 2023;25(4):e0423. https://doi.org/10.1590/1982-0216/20232540423
» https://doi.org/10.1590/1982-0216/20232540423 -
18 Liu A, Bi H, Li Y, Lee S, Cai J, Mi T et al. Galvanic vestibular stimulation improves subnetwork interactions in Parkinson's disease. J Healthc Eng. 2021;2021:6632394. https://doi.org/10.1155/2021/6632394 PMID: 34094040.
» https://doi.org/10.1155/2021/6632394
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A study conducted at the Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
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Financial support
Dean’s office for research (PRPq) of the Universidade Federal de Minas Gerais, process 02/2025
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Data sharing statement
Participant data will be available for 5 years from the date of publication of this article. The information can be consulted by anyone interested through the link: https://drive.google.com/file/d/1f4fV4-gY146GOVjse02YIj4OcfAAm09F/view?usp=sharing
Participant data will be available for 5 years from the date of publication of this article. The information can be consulted by anyone interested through the link: https://drive.google.com/file/d/1f4fV4-gY146GOVjse02YIj4OcfAAm09F/view?usp=sharing
Evokadus GVS® equipment connected to the computer on the desk, with the software used for stimulations open on the home screen.