Comparison of Cervical Vestibular Evoked Myogenic Potentials in Yakshagana Dancers and Non-Dancers

INTRODUCTION Cervical Vestibular Myogenic Potential [cVEMP] is a neurophysiological test that evaluates the function of the inner ear’s vestibular system1. It measures a rapid electromyography (EMG) response to intense auditory stimuli through the sacculocollic reflex arising from the saccule to the inferior branch of the vestibular nerve and the sternocleidomastoid muscle (SCM)2,3. The cVEMP has four main metrics, including amplitude, asymmetry ratio, threshold, and latency4. Dancing is often recommended to maintain healthy muscle tone, trophism, fluid joint mobility, dexterity and coordination. Dancing enables the development of all the abilities required to maintain balance, including joint mobility and coordination, by shifting the center of gravity, head, and trunk away from the axis of support5. The primary feedback mechanism in dance training is shifted from the visual to the somatosensory system, as evidenced by the fact that professional dancers rely less on their vision than novices6. Comparative studies examining the vestibular system’s functionality in dancers versus non-dancers have been scarce, leaving a noticeable gap in scholarly exploration. Despite sporadic investigations into dancers’ vestibular capabilities, a notable void exists concerning Yakshagana dancers’ vestibular function. The profound body twists and turns in Yakshagana are typically characterized by intense emotional expression. The characters typically exhibit impressive squatting and jumping motions while moving in a circular or semi-circular shape7. Moreover, elucidating the vestibular function in Yakshagana dancers carries practical implications for both performers and healthcare professionals. Such collaborations may yield innovative methodologies for assessing vestibular function in dancers, potentially leading to the development of targeted interventions for vestibular rehabilitation in performing artists.Represents the median values of cVEMP latencies through four bars: Right P1, Right N1, Left P1, and Left N1, corresponding to the P1 and N1 latency values of right and left ears.AIM AND OBJECTIVES The study aimed to investigate cVEMPs in Yakshagana dancers compared to non-dancers. It sought to determine whether there were significant differences in amplitudes, Absolute Asymmetric Ratios [AAR] and latencies between the two groups. MATERIALS AND METHODS This cross-sectional study consisted of 40 adults between 18-40 years and normal pure tone audiometry thresholds [within 15 dB HL]. The participants consisted of 20 participants each in the Control group [Non-dancers] and the Target group [Yakshagana dancers]. The target group included Yakshagana dancers who were trained for at least one year with ensured daily practice sessions of a minimum of one hour. Those with middle ear pathologies or associated problems were excluded. Evaluations were carried out in a well-illuminated sound-treated room. The noise level within the room was within 35 dBA8>. Pure tone thresholds were recorded using a calibrated clinical audiometer Piano Plus VRA [Inventis, Italy]. The cVEMP was recorded using the Smart EP-Duet module, [IHS, USA]. Air conduction thresholds were measured from 250 Hz to 8000 Hz, while bone conduction thresholds were assessed from 250 Hz to 4000 Hz in a sound-treated environment. Participants who met the inclusion criteria after this initial assessment proceeded to Phase II of the study. cVEMP was recorded for all the subjects with a 500 Hz tone burst stimulus. The responses were filtered from 30 Hz to 1500 Hz. 100 stimuli, with a repetition rate of 4.1/s, were presented at a fixed intensity of 106 dBnHL. ETHICAL CONSIDERATIONS Every testing procedure used in this study was non-invasive and conducted following the institute’s ethical approval committee’s guidelines. Before testing, the participants were informed about all test procedures, and all participants gave their informed consent to participate in the study [FMIEC/CCM/018/2024, Father Muller College (Department of Speech and Hearing), Father Muller Charitable Institutions. RESULTS Because the Shapiro-Wilk test revealed a non-normal distribution of the data, the Mann-Whitney U test was applied to group comparisons, using SPSS software v219>. Figure 1 illustrates that both P1 and N1 latencies in both ears are significantly shorter in Yakshagana dancers than non-dancers (Right P1 U = 65.000, p = 0.00; Right N1 U = 84.500, p = 0.003; Left P1 U = 118.000, p = 0.043; Left N1 U = 86.500, p = 0.004). In contrast, no significant difference in cVEMP amplitude between the two groups for either the left ear (U = 206.000, p = 0.065) or right ear (U=221.000, p = 0.384) was noted with the median cVEMP amplitude for non-dancers being 100.98 µV in the right ear (Range: 168 µV; IQR: 61 µV) and 91.26 µV in the left ear (Range: 188 µV; IQR: 38 µV). Similarly, no significant difference was found for the AAR between the two groups (U = 209.000, p = 0.593) with a noted AAR median of 14.15% (Range: 27%; IQR: 15%). DISCUSSION This study demonstrated that the latencies of the cVEMP peaks in both ears of the Yakshagana dancers were shorter than those of the non-dancers. This shorter latency result is inconsistent with the results in Bharatanatyam dancers10> and Latin dancers11> but consistent with the findings in a test group combining Salsa and Bharatanatyam dancers12>. Additionally, we found no significant difference in the cVEMP amplitude or AAR between the dancer and non-dancer groups. This is in agreement with the results in Bharatanatyam dancers10> and Latin dancers11>, with both reporting no amplitude differences. However, they contradict the higher amplitude findings in combined Bharatanatyam–Salsa dancers12,13>, as well as in ballet dancers14>. The inconsistency in latency results among different dance forms may be attributed to variations like dance movements, duration and intensity of training, and methodological differences across studies. Yakshagana is characterized by vigorous, repetitive head and body movements, which provide strong and frequent vestibular stimulation. This could enhance vestibulo-collic reflex efficiency, resulting in shorter cVEMP latencies. In contrast, Bharatanatyam emphasizes controlled and static head postures, while Latin dance involves rhythmic but less rotational head motion, possibly producing different patterns of vestibular adaptation. Furthermore, differences in participant characteristics (such as age, sex, and years of experience) and variations in stimulus parameters, electrode placement, and muscle activation levels during testing may also influence cVEMP outcomes. Therefore, while the present findings partially agree with previous research, the observed discrepancies highlight that vestibular plasticity may be dance style–specific and dependent on the type and intensity of vestibular stimulation experienced during training. The present result suggests that latency is a more sensitive indicator than amplitude in assessing vestibular adaptation. Latency reflects the neural conduction time from the saccular macula to the sternocleidomastoid muscle, providing insight into the efficiency of the sacculocollic reflex pathway2,3>. In contrast, amplitude parameters may be susceptible to external factors such as electrode placement, skin impedance, and variations in muscle tension2>. The shorter P1 and N1 latencies observed in Yakshagana dancers suggest a faster neural transmission within the vestibulocollic pathway, which may reflect adaptive changes resulting from repetitive vestibular stimulation and head movements inherent in this dance form10,12>. However, shorter latencies alone do not directly indicate better balance; rather, they suggest enhanced vestibular responsiveness or neuroplastic adaptation within the vestibular pathways1>. Evidence from dance-based studies supports this interpretation—regular dance practice has been shown to improve postural control, proprioceptive accuracy, and vestibular compensation, likely due to continuous multisensory integration training5,6>. Thus, cVEMP latency changes in dancers may not directly quantify balance; they can be viewed as physiological correlates of improved vestibular efficiency. Yakshagana’s vigorous spinning, bending, and head movements require continuous vestibular recalibration and muscle coordination, thereby strengthening the sacculocollic reflex link between the inner ear and neck muscles13,14>. These adaptations may underpin the dancers’ superior dynamic stability, spatial orientation, and head-neck coordination observed clinically11,12>. Therefore, this study supports the notion that traditional dance forms such as Yakshagana may facilitate vestibular and neuromotor adaptations, contributing to improved body control and spatial awareness. CONCLUSION This study showed that Yakshagana dancers had significantly shorter cVEMP latencies than non-dancers, indicating enhanced vestibular responsiveness. Although shorter latency alone does not directly confirm better balance, previous studies suggest that regular dance training promotes vestibular adaptation and postural control5,12>.Therefore, Yakshagana may serve as a potential culturally based therapeutic approach to support vestibular health and balance improvement, particularly in ageing individuals. CONFLICT OF INTEREST The authors have no conflict of interest to declare.