Diagnostic evolution of vestibular neuritis after long-term monitoring.

INTRODUCTION: The diagnosis of vestibular neuritis is based on clinical and laboratory findings after exclusion of other disease. There are occasional discrepancies between clinical impressions and laboratory results. It could be the first vertigo episode caused by other recurrent vestibular disease, other than vestibular neuritis. OBJECTIVE: This study aimed to analyze the clinical features and identify the diagnostic evolution of patients with clinically suspected vestibular neuritis. METHODS: A total of 201 patients clinically diagnosed with vestibular neuritis were included in this study. Clinical data on the symptoms and signs of vertigo along with the results of vestibular function test were analyzed retrospectively. Patients were categorized in terms of the results of caloric testing (CP - canal paresis) group; canal paresis ≥25%; (MCP -minimal canal paresis) group; canal paresis <25%). Clinical features were compared between the two groups and the final diagnosis was reviewed after long-term follow up of both groups. RESULTS: Out of 201 patients, 57 showed minimal canal paresis (CP<25%) and 144 showed definite canal paresis (CP≥25%). A total of 48 patients (23.8%) experienced another vertigo episode and were re-diagnosed. Recurring vestibular symptoms were seen more frequently in patients with minimal canal paresis (p=0.027). Repeated symptoms were observed on the same affected side more frequently in the CP group. The proportion of final diagnosis were not different between two groups. CONCLUSIONS: Patients with minimal CP are more likely to have recurrent vertigo than patients with definite CP. There was no significant difference in the distribution of the final diagnoses between two groups when the vertigo recurs.

Interpretación de resultados de las pruebas oculomotoras, posicionales y calóricas de la videonistagmografía. Revisión documental / Interpretation of the results of the oculomotor, positional and caloric test of the videonistagmography. Documentary review

Introducción: en la actualidad, se reconocen cuadros vestibulares periféricos y centrales que pueden ser diagnosticados mediante la videonistagmografía (VNG). Los avances en la tecnología han provocado en los profesionales una constante actualización en el uso e interpretación de las distintas pruebas que conlleven, en su lectura cruzada, un diagnóstico acertado y a tratamientos de rehabilitación exitosos. El objetivo fue describir las interpretaciones de los resultados de las pruebas oculomotoras, posicionales y calóricas de la VNG para lograr un diagnóstico detallado de las disfunciones vestibulares. Materiales y métodos: revisión documental obtenida de 40 fuentes reportadas en la literatura científica entre 2010 a 2020 tomadas de bases de datos, tesis de grado y libros. Discusión: dentro de la revisión se encontraron tres categorías (pruebas oculomotoras, posicionales y calóricas) y siete subcategorías (nistagmo espontáneo, nistagmo evocado por la mirada, rastreo, sacadas, optocinético, Dix-Hallpike y roll test). Conclusión: los diversos elementos encontrados en la presente revisión son relevantes ya que precisan no solo el tipo de vértigo, sino también su localización topográfica, lo que favorece el proceso de evaluacióndiagnóstico en la población en general.

Introduction: At present, peripheral and central vestibular frames are recognized that can be diagnosed by videonystagmography (VNG). Advances in technology have caused professionals to constantly update the use and interpretation of the different tests that lead, in their cross-reading, to an accurate diagnosis and successful rehabilitation treatments. The objective was to describe the interpretations of the results of the oculomotor, positional and caloric tests of the VNG, for a detailed diagnosis of the vestibular dysfunctions. Materials and method: Documentary review obtained from 40 sources reported in the scientific literature between 2010 and 2020, taken from databases, thesis and books. Discussion: Within the review, three categories were found (oculomotor, positional and caloric tests) and seven subcategories (spontaneous nystagmus, gaze-evoked nystagmus, tracking, saccades, optokinetic, Dix-Hallpike and roll test). Conclusion: The various elements found in this review are relevant in that they specify not only the type of vertigo but also its topographic location, favoring the evaluation-diagnosis process in the general population.

Diagnostic evolution of vestibular neuritis after long-term monitoring / Evolução diagnóstica da neurite vestibular após monitoração de longo prazo

Abstract Introduction The diagnosis of vestibular neuritis is based on clinical and laboratory findings after exclusion of other disease. There are occasional discrepancies between clinical impressions and laboratory results. It could be the first vertigo episode caused by other recurrent vestibular disease, other than vestibular neuritis. Objective This study aimed to analyze the clinical features and identify the diagnostic evolution of patients with clinically suspected vestibular neuritis. Methods A total of 201 patients clinically diagnosed with vestibular neuritis were included in this study. Clinical data on the symptoms and signs of vertigo along with the results of vestibular function test were analyzed retrospectively. Patients were categorized in terms of the results of caloric testing (CP - canal paresis) group; canal paresis ≥25%; (MCP -minimal canal paresis) group; canal paresis <25%). Clinical features were compared between the two groups and the final diagnosis was reviewed after long-term follow up of both groups. Results Out of 201 patients, 57 showed minimal canal paresis (CP < 25%) and 144 showed definite canal paresis (CP ≥ 25%). A total of 48 patients (23.8%) experienced another vertigo episode and were re-diagnosed. Recurring vestibular symptoms were seen more frequently in patients with minimal canal paresis (p = 0.027). Repeated symptoms were observed on the same affected side more frequently in the CP group. The proportion of final diagnosis were not different between two groups. Conclusions Patients with minimal CP are more likely to have recurrent vertigo than patients with definite CP. There was no significant difference in the distribution of the final diagnoses between two groups when the vertigo recurs.

Resumo Introdução O diagnóstico de neurite vestibular é baseado em achados clínicos e laboratoriais após exclusão de outra doença. Existem discrepâncias ocasionais entre a impressão clínica e os resultados laboratoriais. Pode ser o primeiro episódio de vertigem causado por outra doença vestibular recorrente, além da neurite vestibular. Objetivo Analisar as características clínicas e identificar a evolução diagnóstica de pacientes com suspeita clínica de neurite vestibular. Método Foram incluídos neste estudo 201 pacientes com diagnóstico clínico de neurite vestibular. Os dados clínicos sobre os sintomas e sinais de vertigem e os resultados dos testes de função vestibular foram analisados retrospectivamente. Os pacientes foram categorizados de acordo com os resultados das provas calóricos (Grupo PC: paresia do canal ≥ 25%; Grupo PMC: paresia mínima do canal < 25%). As características clínicas foram comparadas entre os dois grupos e o diagnóstico final foi revisado após o acompanhamento de longo prazo de ambos os grupos. Resultados De 201 pacientes, 57 apresentaram paresia mínima do canal (PC < 25%) e 144 apresentaram paresia definitiva do canal (PC ≥ 25%). Quarenta e oito pacientes (23,8%) apresentaram outro tipo de vertigem e foram diagnosticados novamente. Sintomas vestibulares recorrentes foram observados com mais frequência nos pacientes com paresia mínima do canal (p = 0,027). Sintomas recorrentes no mesmo lado afetado foram observados com mais frequência no Grupo PC. A proporção de diagnóstico final não foi diferente entre os dois grupos. Conclusão Os pacientes com paresia mínima do canal foram mais propensos a apresentar vertigem recorrente que os pacientes com paresia do canal definitiva. Não houve diferença significante na distribuição dos diagnósticos finais entre os dois grupos quando houve recorrência da vertigem.

Reversal of paradoxical stimulation (false inversion) in perforated tympanic membranes by increasing the time of warm stimulation, evidenced by a physical model.

OBJECTIVE: To measure the time required in patients with tympanic perforation to reverse paradoxical stimulation (reverse pseudo-nystagmus) and to create a physical model of the process. METHOD: An analytical, observational, cross-sectional study with vestibular evaluation (electronystagmography) of 52 individuals with tympanic membrane perforation without otorrhea or concomitant disease. Increased duration of caloric stimulation in the presence of paradoxical stimulation (reverse pseudo-nystagmus) reverses nystagmic responses. RESULTS: Reversal of nystagmus was observed in 90.9% of patients. The average reversal time was 105.5 seconds. The physical model we prepared provided supporting evidenced for the effects seen in these individuals: warm stimulation in a moist environment initially caused a decrease in temperature (nystagmus to the unexpected side, which characterizes paradoxical stimulation in the warm caloric test); but, as time passed by, the moisture evaporated, and the temperature gradually increased (reversal of nystagmus). CONCLUSIONS: Increasing the stimulation time can be used as a strategy to differentiate reverse nystagmus from paradoxical stimulation. Confusion is thus avoided in diagnostic findings, allowing peripheral alterations to be distinguished from central ones.

The Impact of Dizziness on the Quality of Life of 235 Individuals who Completed Vestibular Testing in Brazil

Introduction In Vestibular Testing (VT), caloric tests allow evaluation of unilateral weakness (UW) and directional preponderance (DP), where different criteria of normality are adopted in Brazil and worldwide. The Brazilian version of the Dizziness Handicap Inventory (Brazilian DHI) evaluates the impact of dizziness on the quality of life of an individual. Objectives The objective of this research is to evaluate the impact of dizziness on the quality of life of patients undergoing VT, and to relate these findings to the results obtained according to national and international criteria. Methods Cross-sectional analytic study of 235 patients referred for VT in two hospitals. The authors performed the Brazilian DHI, history, static, and dynamic balance tests, positional nystagmus, and the Dix-Hallpike maneuver, as well as vectoelectronystagmography. Subjects were divided into three groups according to UW and DP values. Descriptive statistics and comparisons between groups were performed, considering a significance level of 5% in all analyses. Results Patients groups had 20.9% men, and 79.1% women. There was no significant difference between groups for the scores obtained in the Brazilian DHI. There was, however, a statistically significant difference in the redistribution of individuals according to the UWand DP values. Conclusion There was no relationship between VT results and the impact of dizziness in the quality of life. A review of normal values for UW and DP adopted in Brazil is suggested, as well as the application of the Brazilian DHI as an additional tool to evaluate the impact of dizziness on quality of life in all patients undergoing VT.

The Impact of Dizziness on the Quality of Life of 235 Individuals who Completed Vestibular Testing in Brazil.

Introduction In Vestibular Testing (VT), caloric tests allow evaluation of unilateral weakness (UW) and directional preponderance (DP), where different criteria of normality are adopted in Brazil and worldwide. The Brazilian version of the Dizziness Handicap Inventory (Brazilian DHI) evaluates the impact of dizziness on the quality of life of an individual. Objectives The objective of this research is to evaluate the impact of dizziness on the quality of life of patients undergoing VT, and to relate these findings to the results obtained according to national and international criteria. Methods Cross-sectional analytic study of 235 patients referred for VT in two hospitals. The authors performed the Brazilian DHI, history, static, and dynamic balance tests, positional nystagmus, and the Dix-Hallpike maneuver, as well as vectoelectronystagmography. Subjects were divided into three groups according to UW and DP values. Descriptive statistics and comparisons between groups were performed, considering a significance level of 5% in all analyses. Results Patients groups had 20.9% men, and 79.1% women. There was no significant difference between groups for the scores obtained in the Brazilian DHI. There was, however, a statistically significant difference in the redistribution of individuals according to the UW and DP values. Conclusion There was no relationship between VT results and the impact of dizziness in the quality of life. A review of normal values for UW and DP adopted in Brazil is suggested, as well as the application of the Brazilian DHI as an additional tool to evaluate the impact of dizziness on quality of life in all patients undergoing VT.

Do nistagmo às provas calóricas com ar e com água / From nystagmus to the air and water caloric tests

A prova calórica é uma importante ferramenta na avaliação da função labiríntica. OBJETIVO: Comparar o nistagmo pós-calórico da prova com ar a 50ºC e 24ºC com o da prova com água a 44ºC e 30ºC. Desenho científico: Estudo clínico cruzado randomizado. MATERIAL E MÉTODO: 40 indivíduos hígidos submetidos à avaliação da função vestibular incluindo a prova calórica com ar a 50ºC e 24ºC e com água a 44ºC e 30ºC. RESULTADOS: À comparação das provas com ar e com água, não houve diferença significante entre os valores da velocidade angular da componente lenta (VACL) do nistagmo pós-calórico quanto à ordem de realização das estimulações, entre as orelhas e entre os valores de predomínio labiríntico e de preponderância direcional. Os valores da VACL foram maiores nas estimulações com água (p = 0,008; p < 0,001) e a temperatura fria evocou respostas mais intensas (p < 0,001). CONCLUSÃO: À comparação entre as provas com ar a 50ºC e 24ºC e com água a 44ºC e 30ºC, observam-se valores de velocidade da componente lenta similares em ambas as orelhas, maiores na temperatura fria e na prova com água e resultados semelhantes de predomínio labiríntico ou de preponderância direcional do nistagmo pós-calórico em ambas as provas.

The caloric test is an important tool for the assessment of labyrinthine function. OBJECTIVE: To compare the nystagmus response in the caloric tests with air at 50ºC and 24ºC and with water at 44ºC and 30ºC. Study Design: Randomized crossover clinical trial. MATERIALS AND METHODS: 40 healthy individuals were submitted to a neurotological evaluation, including caloric tests with air at 50ºC and 24ºC and water at 44ºC and 30ºC. RESULTS: Comparing the air and water caloric tests, there were no significant differences among the post-caloric nystagmus slow-phase velocity in relation to the stimulation order, between ears and between the values of unilateral weakness and directional preponderance. The slow-phase velocity values were higher with water (p = 0.008, p < 0.001), and cold stimulation produced stronger responses (p < 0.001). CONCLUSION: Comparing 50ºC and 24ºC air caloric test and 44ºC and 30ºC water caloric test, we observed similar slow-phase velocity values for both ears, higher responses in the cold temperature and in the test with water, and similar results of unilateral weakness or directional preponderance for post-caloric nystagmus in both tests.

Estimulação calórica a ar em mastoidectomias abertas unilaterais / Air caloric test in canal wall down mastoidectomy

Poucos trabalhos desde a década de 70 foram realizados a fim de elucidar a prova calórica em alterações da orelha média, apesar de inúmeras controvérsias que este exame pode trazer em estruturas anatômicas tão distintas. Na mastoidectomia radical, estes estudos são mais escassos. OBJETIVO: Este estudo teve como objetivo analisar os achados da estimulação calórica a ar em indivíduos com mastoidectomia radical unilateral sem queixas de tontura. MATERIAL E MÉTODO: Estudo prospectivo, realização da estimulação calórica a ar em 36 indivíduos sem queixas vestibulares, sendo 21 com cirurgia de mastoidectomia aberta unilateral e 15 sem nenhuma alteração na orelha média ou externa. RESULTADOS: 80,95% dos indivíduos apresentaram respostas assimétricas na prova calórica frias, sendo as respostas maiores do lado da mastoidectomia aberta. Em 72,73%, o mesmo efeito ocorreu com a prova calórica quente. Na análise das quatro estimulações, encontrou-se assimetria das provas quente e frias em 81,82% dos casos. Em 47,61%, foi encontrada estimulação paradoxal da prova calórica quente. CONCLUSÃO:As respostas nistágmicas do lado da mastoidectomia aberta foram maiores se comparadas com o lado saudável. A estimulação paradoxal da prova calórica quente foi um achado frequente. Não foram encontradas respostas hipofuncionantes.

Since the 1970s, few studies have been conducted to elucidate the use of caloric tests on middle ear disorders, despite the many controversies that this test may produce in anatomical structures that are so distinct. In cases of mastoidectomy, such studies are even rarer. OBJECTIVE: This study aims to analyze the findings from air caloric stimulation done in individuals submitted to unilateral radical mastoidectomy without complaints of dizziness. MATERIALS AND METHOD: Thirty-six individuals without vestibular complaints were enrolled in this prospective study. Air caloric stimulation was offered to all subjects. Twenty-one individuals had undergone unilateral open mastoidectomy and 15 did not present any middle or outer ear abnormalities. RESULTS: 80.95% of the individuals presented asymmetrical responses in the cold caloric test, with greater response on the side of the open mastectomy. In 72.73% of the subjects the same effect was observed in the hot caloric test. The four stimulation modes revealed asymmetries in both hot and cold tests in 81.82% of the cases. Paradoxical stimulation was observed in 47.61% of hot caloric tests. CONCLUSION: Nystagmic responses on the side of the open mastoidectomy were greater than on the healthy side. Paradoxical stimulation in caloric tests was a frequent finding. No hypofunctioning responses were found.

Validade da prova calórica monotermal em comparação à estimulação bitermal / Validity of the monothermal caloric testing when compared to bithermal stimulation

Background: the use of monothermal caloric testing as a screening tool for vestibular asymmetry has been considered as an alternative to bithermal caloric testing. AIM: to evaluate the effectiveness of monothermal stimulation when compared to bithermal stimulation in the diagnosis of labyrinth asymmetry. Method: the results of 389 vectoelectronystagmography, performed between 1998 and 2007, were analyzed. Monothermal stimulation at 30oC and 44ºC with unilateral weakness (UW) cut-off at 20 percent and 25 percent was compared to bithermal stimulation with cut-off at 25 percent (gold standard). The analysis was aimed at finding which kind of monothermal caloric test (30oC or 44oC) and which kind of cut-off (20 percent or 25 percent) presented the highest specificity and sensitivity values in comparison with bithermal caloric testing. Results: sensitivity and specificity of monothermal caloric tests were: 84 percent and 80 percent, at 30°C with UW at 20 percent; 78 percent and 90 percent, at 30°C with UW at 25 percent; 81 percent and 78 percent, at 44°C with UW at 20 percent; 76 percent and 85 percent, at 44°C with UW at 25 percent. Conclusion: monothermal caloric testing with 30°C stimulus presented the highest sensibility and specificity values in comparison to the results obtained with bithermal stimulation. However, no significant difference was observed between such values and those obtained with 44°C stimulus. In all of the analyses, monothermal testing presented low sensitivity. Thus, the abnormal result of bithermal caloric testing might be seen as normal in monothermal stimulation. The use of monothermal testing as a screening tool is better recommended for individuals whose medical history suggests a low probability of vestibular disease.

Tema: a estimulação calórica monotermal tem sido considerada como alternativa à prova calórica bitermal para triagem das assimetrias vestibulares. Objetivo: avaliar a confiabilidade da estimulação monotermal em relação à bitermal para o diagnóstico das assimetrias labirínticas. Método: avaliaram-se 389 resultados de vectoelectronistagmografia realizados entre 1998 e 2007. A estimulação monotermal de 30ºC e 44ºC com pontos de corte de predomínio labiríntico (PL) em 20 por cento e em 25 por cento foi comparada à bitermal com ponto de corte em 25 por cento (padrão ouro). Na análise, interessou encontrar qual foi à prova monotemal (30°C ou 44°C) e com qual ponto de corte (20 por cento ou 25 por cento) que apresentou os valores mais elevados de sensibilidade e especificidade quando comparada à prova bitermal. Resultados: a sensibilidade e especificidade da prova monotermal foram respectivamente de: 84 por cento e 80 por cento, a 30°C com PL em 20 por cento; 78 por cento e 90 por cento, a 30°C com PL em 25 por cento; 81 por cento e 78 por cento, a 44°C com PL em 20 por cento; 76 por cento e 85 por cento, a 44°C com PL em 25 por cento. Conclusão: a prova monotermal com estimulo a 30°C apresentou valores mais elevados de sensibilidade e especificidade quando comparada a bitermal. Contudo, não se observou diferença significativa em relação aos valores observados com estímulo a 44°C. Em todas as análises, a prova monotermal apresentou a limitação da baixa sensibilidade, de modo que testes alterados pela bitermal podem passar como normais pela prova monoternal. Ao se decidir pela realização da prova monotermal como triagem, deve-se realizá-la em indivíduos com menor probabilidade de estar com doença vestibular, a partir da história clínica.

Air stimulation in tympanic perforation: inverted nystagmus study / Estimulação a ar na perfuração timpânica: estudo da inversão nistágmica

Response inversion during warm air stimulation is the most controversial finding seen in caloric tests of individuals with tympanic membrane perforation. In such cases, very few studies explore the possible interferences found in the caloric test, bringing about controversies in the interpretation of test results. AIM: This paper aimed at analyzing warm air stimulation effects in individuals with tympanic membrane perforation in comparison with normal healthy controls. MATERIALS AND METHODS: Prospective, non-randomized study in which 48 individuals without vestibular complaints were assessed, 33 had one tympanic membrane perforated and 15 had no ear drum alteration. RESULTS: 39.39 percent of the individuals had response inversion found during the warm air test. In the absence of this phenomenon, nystagmus responses were symmetrical. CONCLUSION: Nystagmus responses to the caloric test in individuals with tympanic membrane perforation were similar to those from healthy controls, with the exception of the fact that they had inverted responses in the warm caloric test.

A inversão de respostas durante a estimulação a ar quente é o achado mais controverso que aparece na prova calórica de indivíduos com perfuração da membrana timpânica. Nestes casos, poucos estudos exploraram as possíveis interferências nos achados da prova calórica, trazendo controvérsias de interpretação no resultado do exame. OBJETIVO: Este trabalho teve o objetivo de analisar a estimulação calórica a ar em indivíduos com perfuração da membrana timpânica em comparação com indivíduos hígidos, sem esta alteração. MATERIAL E MÉTODO: Estudo prospectivo, não-randomizado, no qual foram avaliados 48 indivíduos sem queixas vestibulares, sendo 33 indivíduos com membrana timpânica perfurada unilateralmente e 15 indivíduos sem nenhuma alteração na membrana timpânica. RESULTADOS: 39,39 por cento dos indivíduos apresentaram inversão de respostas na prova calórica a ar quente. Na ausência deste fenômeno as respostas das nistágmicas foram simétricas. CONCLUSÃO: As respostas nistágmicas na prova calórica em indivíduos com perfuração da membrana timpânica foram similares aos indivíduos hígidos, com exceção da presença de inversão de respostas na prova calórica quente.

Achados à prova calórica e canal semicircular acometido na vertigem posicional paroxística benigna / Caloric test results and damaged semicircular canal in benign positional paroxysmal vertigo

OBJETIVO: Caracterizar os achados da prova calórica em pacientes com vertigem posicional paroxística benigna, segundo o canal semicircular comprometido. MÉTODOS: Foram analisados 1033 prontuários de pacientes submetidos à pesquisa de nistagmo posicional e de posicionamento e à eletronistagmografia. Os achados da prova calórica, de acordo com os canais semicirculares acometidos, foram submetidos à análise estatística. RESULTADOS: No comprometimento de canal posterior, houve prevalência de normorreflexia (p<0,0001); hiporreflexia prevaleceu sobre hiper-reflexia (p<0,0001) e preponderância direcional (p<0,0001), e hiper-reflexia prevaleceu sobre preponderância direcional (p<0,0001). No comprometimento de canal lateral, normorreflexia prevaleceu sobre hiporreflexia (p<0,0001) e hiper-reflexia (p<0,0001); hiporreflexia tendeu a prevalecer sobre hiper-reflexia (p=0,0771), e preponderância direcional não ocorreu. No comprometimento de canal anterior, normorreflexia prevaleceu sobre hiporreflexia (p<0,0001); hiper-reflexia e preponderância direcional não ocorreram. CONCLUSÃO: Na prova calórica de pacientes com vertigem posicional paroxística benigna, normorreflexia, hiporreflexia, hiper-reflexia ou preponderância direcional do nistagmo pós-calórico ocorrem em ordem decrescente de prevalência, quando há comprometimento do canal posterior; normorreflexia prevalece sobre hiporreflexia ou hiper-reflexia e hiporreflexia tende a prevalecer sobre hiper-reflexia, no comprometimento do canal lateral; normorreflexia prevalece sobre hiporreflexia, no comprometimento do canal anterior.

PURPOSE: To characterize caloric test results in benign paroxysmal positional vertigo patients, according to the damaged semicircular canal. METHODS: The data of 1033 patients submitted to Dix-Hallpike testing, positional nystagmus and electronystagmography were analyzed. Caloric test results were compared to the damaged semicircular canals and were submitted to statistical analysis. RESULTS: In cases with posterior canal damage, there was prevalence of normal responses compared to abnormal results (p<0.0001); hypo activity was more prevalent than hyperactivity (p<0.0001) and directional preponderance (p<0.0001), and hyperactivity more prevalent than directional preponderance (p<0.0001). In cases with lateral canal damage, normal responses were more prevalent than hypo activity (p<0.0001) and hyperactivity (p<0.0001); there was a tendency of prevalence of hypo activity over hyperactivity (p=0.0771), and directional preponderance was not observed. In cases with anterior canal damage, normal responses were more prevalent than hypo activity (p<0.0001); hyperactivity and directional preponderance were not observed. CONCLUSION: In the caloric test of benign positional paroxysmal vertigo patients, normal responses, hypo activity, hyperactivity or directional preponderance of post-caloric nystagmus occur in decreasing order of prevalence when the posterior canal is damaged; normal responses are more prevalent than hypoactive or hyperactive caloric responses, and there is a tendency of prevalence of hypoactive over hyperactive caloric responses when the lateral canal is damaged; normal responses are more prevalent than hypoactive caloric responses when the anterior canal is damaged.