Vestibular end-organ impairment in an animal model of type 2 diabetes mellitus

When, where, and why should we look for vestibular dysfunction in people with diabetes mellitus?

The biochemistry of diabetes mellitus results in multi-system tissue compromise that reduces functional mobility and interferes with disease management. Sensory system compromise, such as peripheral neuropathy and retinopathy, are specific examples of tissue compromise detrimental to functional mobility. There is lack of clarity regarding if, when, and where parallel changes in the peripheral vestibular system, an additional essential sensory system for functional mobility, occur as a result of diabetes. Given the systemic nature of diabetes and the plasticity of the vestibular system, there is even less clarity regarding if potential vestibular system changes impact functional mobility in a meaningful fashion. This commentary will provide insight as to when we should employ diagnostic vestibular function tests in people with diabetes, where in the periphery we should look, and why testing may or may not matter. The commentary concludes with recommendations for future research and clinical care.

The Adaptation of Participation Scale Short Simplified Questionnaire into Indonesian Language and the Psychometric Properties in Individuals with Type 2 Diabetes Mellitus with Vestibular Dysfunction

Background

Type 2 diabetes mellitus (T2DM) has been reported to affect the vestibular system resulting in dizziness and vertigo complaints. This complication is known to disable the social participation. The Participation Scale Short Simplified (PSSS) has been developed to quantify the severity of social participation restrictions. The aim of this study was to translate and cross-culturally adapt the PSSS into Indonesian Bahasa (PSSS-Ina). The measurement properties of the translated version and the factors contributing to the severe participation restriction were determined.

Methods

The participants comprised 55 T2DM with vestibular dysfunction (VD) in the community center for diabetes mellitus in Central Java, Indonesia. The signs of VD were confirmed by head impulse test, Dix Hallpike Test, and supine roll test. The PSSS-Ina was administered twice with a four-week interval. The physical examination was also performed to identify the contributing factors.

Results

The test–retest reliability of the PSSS Indonesian Bahasa version (PSSS-Ina) between two measurement sessions was excellent (ICC of 0.93, p < 0.001, and 95% CI: 0.88–0.95). The correlation coefficient between two administrations was high (r = 0.88). Based on the demonstrated content validity, the values of the corrected item and total correlation were greater than 0.3. No floor and ceiling effects were observed. The good internal consistency was confirmed with Cronbach's alpha of 0.84. The factor analysis produced three factors of activity participation, social engagement, and work-related participation. The multiple logistic regression revealed that the balance performance of mCTSIB was the main factor contributing to the severe participation restriction reflected by the PSSS-Ina score.

Conclusion

The Indonesian version of the PSSS-Ina demonstrated excellent comprehensibility and reliability in individuals suffering T2DM with VD. This tool is therefore helpful in identifying the participation limitation in individuals with VD.

Residual Dizziness in Elderly Patients after Benign Paroxysmal Positional Vertigo

INTRODUCTION

The aim of this study was to compare the effects of Brandt-Daroff (BD) exercise and shopping exercise (SE) on the resolution of residual dizziness (RD) in patients with benign paroxysmal positional vertigo (BPPV) following a successful modified Epley canalith repositioning maneuver (CRP).

METHODS

This single-blind, randomized clinical trial included patients with posterior semicircular canal type of BPPV. Following the modified Epley maneuver, patients that experienced RD were randomly assigned to 3 groups: (i) BD, (ii) SE, and (iii) control groups. Primary outcomes were quantified using the Dizziness Handicap Inventory (DHI).

RESULTS

Following CRP, 240 (63%) participants experienced RD. All these patients were followed up weekly for RD. After the resolution of RD, patients were followed up monthly for recurrence. Mean time to recovery was 16.4 ± 10 (range, 5-49) days in the BD group, 11.5 ± 4.6 (range, 6-32) days in the SE group, and 23.4 ± 16.8 (range, 6-89) days in the control group. The SE group recovered significantly faster than the BD and control groups (p < 0.001). Baseline emotional DHI (E-DHI) scores were significantly correlated with the duration of pre-CRP symptoms (p < 0.001). Correlation analysis indicated that patients with obesity and diabetes mellitus (DM) recovered later than patients without these comorbidities.

CONCLUSION

We found that RD improved significantly in the SE group compared to the BD and control groups. Additionally, a significant relationship was established between RD and high anxiety levels and DM, and obesity had a negative impact on the resolution of RD.

Postural balance in type 2 diabetics with vertigo, dizziness and/or unsteadiness

PURPOSE

To evaluate the postural balance of type 2 diabetics with vertigo, dizziness, and/or unsteadiness.

METHODS

limit of stability, pressure center displacement area, and sway velocity of 20 patients with type 2 diabetes were compared with 22 controls using the Balance Rehabilitation Unit (BRUTM, Medicaa) posturography.

RESULTS

Compared to the control group, patients with type 2 diabetes showed a significantly lower limit of stability and a significantly higher-pressure center displacement area on a firm surface with eyes open, eyes closed, and horizontal vestibular-visual interaction; and higher sway velocity on a firm surface with eyes open and with eyes closed.

CONCLUSION

type 2 diabetics with vertigo, dizziness, and/or imbalance compromised postural balance related to visual stimuli and vestibular-visual interaction and moderate impairment in the quality of life.

Diabetes and Auditory-Vestibular Pathology

The relationship between diabetes mellitus (DM) and the auditory/vestibular system has been investigated for more than a century. Most population-based investigations of hearing loss in persons with diabetes (PWD) have revealed a slow progressive, bilateral, high-frequency sensorineural hearing loss. Despite the growing research literature on the pathophysiology of DM-related hearing loss using various animal models and other human studies, knowledge of specific mechanism of the degenerative changes of the inner ear and/or auditory nerve is far from full elucidation. Recent investigations of the mechanisms underlying the association between hearing loss and DM suggest complex combined contributions of hyperglycemia, oxidative stress resulting in cochlear microangiopathy, and auditory neuropathy. An even lesser understood complication of DM is the effect on the vestibular system. Here we provide an overview of animal and human evidence of pathophysiological changes created by DM and its effects on auditory-vestibular anatomy and function.

Vestibular evoked myogenic potentials in patients with diabetes mellitus

Although the exact mechanism and most involved region of the vestibular system have not yet been fully clarified, vestibular dysfunction has been demonstrated in patients with diabetes mellitus (DM). Vestibular evoked myogenic potential (VEMP) is a short latency electromyographic response to sound or vibration stimuli that may reflect otolith organ or related reflex functions. Since its first description in 1992, VEMP has become a significant part of the vestibular test battery as an objective measurement tool. In diabetic patients, VEMP responses have been studied in order to determine any otolith organ or related reflex dysfunctions. Here, we review the literature with regard to VEMP findings representing any peripheral vestibular end-organ dysfunction in patients with DM. Distinctive vestibular end-organ impairments seem to be demonstrated in patients with DM either with or without DNP via objective vestibular testing tools including VEMP recordings according to relevant studies. However, further studies with larger sample sizes are required to reveal the more definitive findings of VEMP recordings regarding the vestibular pathologies in patients with DM.

Impairment of Vestibular Function and Balance Control in Patients with Type 2 Diabetes

BACKGROUND

Recent evidence suggests that falls are a major complication of diabetes in elderly patients, leading to disability and preventable death. However, the potential risk factors leading to falls in patients with type 2 diabetes are not fully understood. This study was designed to explore the characteristics of vestibular dysfunction and balance control in patients with type 2 diabetes and to analyse the risk factors associated with falls.

METHODS

The study recruited 51 patients with type 2 diabetes and 43 controls who underwent vestibular function tests and balance control capability tests between January 2013 and December 2015. Vestibular function and balance control capability assessment was based on slow-phase velocity, canal paresis, Sensory Organisation Test (SOT) score, Limits of Stability Test (LOS) score, and Motor Control Test (MCT) score.

RESULTS

In all, 56.7% of the diabetic patients had vestibular dysfunction, compared with 27.9% of the controls (p = 0.005). Vestibular dysfunction was dependent on the duration of the disease and serum HbA1c levels. There were no significant differences between the two groups with respect to the balance test results for SOT score, somatosensory subtest score, vestibular subtest score, or LOS score. However, the visual system and MCT scores were significantly lower in the diabetic patients than in the controls (p = 0.032 and p = 0.018, respectively).

CONCLUSIONS

Patients with type 2 diabetes have a higher incidence of vestibular dysfunction. Vestibular dysfunction, visual system impairment, and a decline in motion control may be the risk factors that can lead to falls, and thus need to be managed accordingly in diabetic patients.

Utricular hypofunction in patients with type 2 diabetes mellitus

The aim of this study was to assess the function of the utricle and horizontal semicircular canals in patients with type 2 diabetes mellitus receiving primary health care, with/without a history of falls. 101 patients with type 2 diabetes mellitus, 34 to 84 years old (26 with and 75 without a history of falls) and 51 healthy volunteers (40-83 years old) accepted to participate. They denied having a history of dizziness, vertigo, unsteadiness, hearing loss, or neurological disorders. None of them were seeking care due to sensory or balance decline. After a clinical evaluation and report of symptoms related to balance using a standardised questionnaire, lateral canal function was assessed by sinusoidal rotation at 0.16 Hz and 1.28 Hz (60°/sec peak velocity), otolith function was assessed by static visual vertical (average of 10 trials) and dynamic visual vertical during unilateral centrifugation (300°/sec at 3.5 cm) and static posturography was performed on hard/ soft surface with eyes open/closed. Compared to healthy volunteers, patients showed decreased responses to unilateral centrifugation, but similar responses to horizontal canal stimuli (independently of age, peripheral neuropathy or a history of falls) (ANCoVA p < 0.05) and a larger sway area with a lengthier sway path. Compared to patients with no falls, patients with falls had a higher female/male ratio and a higher frequency of score ≥ 4 on the questionnaire of symptoms related to balance, but similar age, body mass index and frequency of peripheral neuropathy. In patients with type 2 diabetes mellitus, receiving primary healthcare who are not seeking care due to sensory or balance decline, utricular function may be impaired even in the absence of horizontal canal dysfunction or a history of falls.

Otolith Dysfunction in Persons With Both Diabetes and Benign Paroxysmal Positional Vertigo

OBJECTIVE

Vestibular dysfunction is a well-recognized complication of type 2 diabetes (DM) that may contribute to increased fall risk. The prevalence of benign paroxysmal positional vertigo (BPPV) is higher in people with DM. The impact of DM on the otolith organs of the vestibular system in people with BPPV is unknown. The purpose of this study was to analyze otolith function using vestibular-evoked myogenic potential (VEMP) tests in people with DM and concurrent BPPV (BPPV + DM), and to examine the relationships between VEMP variables and diabetes-related variables.

STUDY DESIGN

Prospective, cross-sectional study.

SETTING

Tertiary academic medical center.

SUBJECTS AND METHODS

Participants 40 to 65 years were recruited in four groups: controls (n = 20), people with DM (n = 19), BPPV (n = 18), and BPPV + DM (n = 14). Saccule and utricle function were examined using cervical VEMP (cVEMP) and ocular VEMP (oVEMP), respectively. Diabetes-related variables such as HbA1c, duration of diabetes, and presence of sensory impairment due to diabetes were collected.

RESULTS

The frequency of abnormal cVEMP responses was higher in the DM (p = 0.005), BPPV (p = 0.003), and BPPV + DM (p <0.001) groups compared with controls. In the participants with diabetes, higher HbA1c levels were correlated with prolonged P1 (p = 0.03) and N1 latencies (p = 0.03). The frequency of abnormal oVEMP responses was not different between groups (p = 0.2).

CONCLUSION

Although BPPV and DM may independently affect utricle and saccule function, they do not seem to have a distinct cumulative effect.

Vascular and Neuroepithelial Histopathology of the Saccule in Humans With Diabetes Mellitus

HYPOTHESIS

This study aimed to determine if there are quantitative differences in the neuroepithelium and microvasculature of the saccule between subjects with and without diabetes mellitus (DM).

BACKGROUND

Histopathologic changes that may underlie the association between DM and vestibular dysfunction have not been characterized in humans.

METHODS

Human temporal bones (HTBs) from 39 subjects with DM (n = 16 type I DM [T1DM], n = 23 type II DM [T2DM]) were compared with 40 group age-matched controls. Vessel wall thickness was measured from the saccular arteriole. Type I and type II vestibular hair cell (VHC) counts were performed on perpendicularly oriented saccular maculae using differential interference contrast microscopy (T1DM: 5HTB/3 subjects; T2DM: 9HTB/8 subjects; controls: 25HTB/20 subjects).

RESULTS

The mean density of type I VHCs was 16 to 17% lower in the DM groups compared to controls (T1DM 52.21 [4.26], T2DM 53.3 [5.34], control 63.14 [2.49] cells/mm, p = 0.02). There were no differences between T1DM, T2DM, and control groups in type II VHC density (T1DM 40.89 [5.17], T2DM 40.44 [6.93], control 42.80 [1.79] cells/mm, p = 0.92) or in mean vessel wall thickness (T1DM 2.23 [0.62], T2DM 2.18 [0.53], control 2.00 [0.53] μm, p = 0.26).

CONCLUSION

Neuroepithelial pathology, manifested as lower density of type I VHCs, was observed in the saccules of subjects with DM. Saccular microangiopathy, expressed as alterations in arteriole thickness, was not observed. These findings are consistent with histologic observations in animals with experimentally induced diabetes. DM may have a selective and deleterious effect on human vestibular sensory epithelia.

Postural visual dependence in asymptomatic type 2 diabetic patients without peripheral neuropathy during a postural challenging task

Increasing evidence indicates that diabetes may negatively affect vestibular function, and postural control more so under postural challenging conditions. Healthy and diabetic subjects were compared on visual control of posture during a postural challenging task.

METHODS

Forty-eight asymptomatic patients with type 2 diabetes free of peripheral neuropathy and 29 age-matched normal subjects were compared on postural stability on a high-density foam block with computerized posturography. Sway parameters were measured and Romberg ratios calculated and compared between the two groups.

RESULTS

For subjects who succeeded in maintaining balance, all sway parameters were larger in the diabetics with vision available. With eye closure, only the sway area was almost significantly larger and of greater variability in diabetics, but with a smaller and less variable Romberg ratio. Among the two groups and visual conditions, the tightest anterioposterior-mediolateral (AP-ML) coupling was found in diabetics during eye closure. Differences in anthropometric factors did not influence postural sway.

CONCLUSIONS

Despite the smaller Romberg ratios in diabetics than controls, findings still suggest greater but masked postural visual dependence in diabetics faced with postural challenging situations due to subclinical vestibular deficits. They also indicate that diabetics may be vulnerable before any clinical signs of peripheral neuropathy arise to falls on unstable surfaces especially in poorly lit areas, and may require to employ other complex postural tactics such as stiffening to maintain their balance.

Impact of Diabetic Complications on Balance and Falls: Contribution of the Vestibular System

Diabetes causes many complications, including retinopathy and peripheral neuropathy, which are well understood as contributing to gait instability and falls. A less understood complication of diabetes is the effect on the vestibular system. The vestibular system contributes significantly to balance in static and dynamic conditions by providing spatially orienting information. It is noteworthy that diabetes has been reported to affect vestibular function in both animal and clinical studies. Pathophysiological changes in peripheral and central vestibular structures due to diabetes have been noted. Vestibular dysfunction is associated with impaired balance and a higher risk of falls. As the prevalence of diabetes increases, so does the potential for falls due to diabetic complications. The purpose of this perspective article is to present evidence on the pathophysiology of diabetes-related complications and their influence on balance and falls, with specific attention to emerging evidence of vestibular dysfunction due to diabetes. Understanding this relationship may be useful for screening (by physical therapists) for possible vestibular dysfunction in people with diabetes and for further developing and testing the efficacy of interventions to reduce falls in this population.

Sensory Functions, Balance, and Mobility in Older Adults With Type 2 Diabetes Without Overt Diabetic Peripheral Neuropathy: A Brief Report

This study examined possible subtle degradation in sensory functions, balance, and mobility in older adults with type 2 diabetes (T2D) prior to overt development of diabetic peripheral neuropathy (DPN). Twenty-five healthy controls (HC group, age = 74.6 ± 5.4) and 35 T2D elderly without DPN (T2D group, age = 70.6 ± 4.7) were recruited. Sensory assessment included vibrotactile sensitivity, bilateral caloric weakness, and visual contrast sensitivity. Self-report measures comprised of Activity-Specific Balance Confidence (ABC), Human Activity Profile–adjusted activity scores (HAP-AAS), falls, and mobility disability. Performance measures included modified Timed-Up and Go (mTUG), Clinical Test of Sensory Integration for Balance (mCTSIB), and Frailty and Injuries (FICSIT-4) balance test. T2D group demonstrated significantly worse bilateral caloric weakness, marginally higher threshold of vibrotactile sensitivity and lower visual contrast sensitivity, and as well as signifcantly lower HAP-AAS. A significantly higher proportion of the T2D group failed mCTSIB Condition 4 than in the HC group. Subtle changes in multiple sensory systems of older adults with T2D may reduce redundancy available for balance control while performing challenging activities much before DPN development.

The effects of diabetes and/or peripheral neuropathy in detecting short postural perturbations in mature adults

Background

This study explored the effects of diabetes mellitus (DM) and peripheral neuropathy (PN) on the ability to detect near-threshold postural perturbations.

Methods

83 subjects participated; 32 with type II DM (25 with PN and 7 without PN), 19 with PN without DM, and 32 without DM or PN. Peak acceleration thresholds for detecting anterior platform translations of 1 mm, 4 mm, and 16 mm displacements were determined. A 2(DM) × 2(PN) factorial MANCOVA with weight as a covariate was calculated to compare acceleration detection thresholds among subjects who had DM or did not and who had PN or did not.

Results

There was a main effect for DM but not for PN. Post hoc analysis revealed that subjects with DM required higher accelerations to detect a 1 mm and 4 mm displacement.

Conclusion

Our findings suggest that PN may not be the only cause of impaired balance in people with DM. Clinicians should be aware that diabetes itself might negatively impact the postural control system.

The effect of hydrogen peroxide applied to the middle ear on inner ear function

OBJECTIVES/HYPOTHESIS

The objective was to assess the effect of hydrogen peroxide applied to the middle ear on cochlear and vestibular function.

STUDY DESIGN

Prospective animal study.

METHODS

Sand rats underwent a right-side total labyrinthectomy, and a polyethylene tube was inserted into the left-side middle ear. Following baseline recordings of vestibular evoked potentials in response to linear acceleration stimuli and auditory brainstem response, each experimental animal received five daily applications of hydrogen peroxide into the left-side middle ear. Two control groups received saline and gentamicin, respectively. Subsequently, recordings were repeated and compared with baseline measurements.

RESULTS

Saline administration affected neither vestibular evoked potentials nor auditory brainstem response. In contrast, both responses could not be recorded following gentamicin application. After hydrogen peroxide administration, auditory brainstem response could not be recorded in 25% (3 of 12) of the animals, whereas in the remaining nine animals the average auditory brainstem response threshold was significantly elevated by 55 dB (P =.000002). Linear vestibular evoked potentials could not be recorded in 42% (5 of 12) of the animals.

CONCLUSION

It appears that topical hydrogen peroxide adversely affects both cochlear and vestibular function of the sand rat. The study demonstrated the effect of a reactive oxygen species on inner ear function and may be useful in the study of mechanisms responsible for this damage and its protection. Clinically, although an animal model was used in the present study, caution should be exercised when large amounts of hydrogen peroxide are applied to a dry, perforated ear.

Metabolic disorders prevalence in sudden deafness

OBJECTIVES

The aim of the present study was to establish the frequency of metabolic disorders among patients with sudden deafness and to compare this frequency with data from population surveys.

INTRODUCTION

No consensus has been reached regarding the prevalence of metabolic disorders among sudden deafness patients or their influence as associated risk factors.

METHODS

This cross-sectional study enrolled all sudden deafness patients treated in the Otolaryngology Department of the University of São Paulo between January 1996 and December 2006. Patients were subjected to laboratory exams including glucose and cholesterol levels, low-density lipoprotein cholesterol fraction, triglycerides, free T4 and TSH.

RESULTS

The sample comprised 166 patients. We observed normal glucose levels in 101 (81.5%) patients and hyperglycemia in 23 (18.5%) patients, which is significantly different (p < 0.0001) compared to the diabetes mellitus prevalence (7.6%) in the Brazilian population. Cholesterol levels were normal in 78 patients (49.7%) and abnormal in 79 (50.3%) patients, which is significantly different compared to the Brazilian population (p = 0.0093). However, no differences were observed in low-density lipoprotein cholesterol fraction (p = 0.1087) or triglyceride levels (p = 0.1474) between sudden hearing loss patients and the Brazilian population. Normal levels of thyroid hormones were observed in 116 patients (78.4%), and abnormal levels were observed in 32 (21.6%) patients. Compared with the prevalence of thyroid disorders in the general population (10%), statistical analysis revealed a significant difference (p = 0.0132) between these two groups.

DISCUSSION

Among sudden deafness patients, we observed frequencies of hyperglycemia and thyroid disorders that were more than twice those of the general population.

CONCLUSIONS

Hyperglycemia and thyroid disorders are much more frequent in patients with sudden deafness than in the general population and should be considered as important associated risk factors.

VEMP responses are not affected in non-insulin-dependent diabetes mellitus patients with or without polyneuropathy

CONCLUSION

Vestibular evoked myogenic responses (VEMPs) are not affected in non-insulin-dependent diabetes mellitus (NIDDM) patients with or without polyneuropathy.

OBJECTIVE

To compare VEMP responses of NIDDM patients and healthy subjects.

SUBJECTS AND METHODS

VEMP responses were collected from 25 NIDDM patients with polyneuropathy (PNP), 13 NIDDM patients without PNP and 21 healthy subjects using click stimulation. After excluding ears with hearing loss (HL) (worse than 25 dB) the VEMP responses (p13 and n21 latencies and amplitude) recorded in 105 dB stimulus intensity were compared.

RESULTS

There was no statistically significant difference between groups. VEMP responses were found to be normal in NIDDM patients with or without PNP.

Otoneurologic findings in Type 1 Diabetes mellitus patients

Summary

Metabolic alterations, as they occur in Diabetes mellitus, have been mentioned in the development and maintenance of complaints related to the vestibular and auditory organs.

Aim

To investigate the vestibular system in Type 1 Diabetic mellitus population.

Material and method

The present study was developed with 19 individuals, being 10 females (52.6%) and 9 males (47.3%), with ages varying from 8 to 25 years old, with medical diagnosis of Type 1 Diabetes mellitus. For result comparison, a control group was selected with others 19 individuals, matching the study group in age and gender. The evaluation protocol encompassed interview, otoscopic inspection, dynamic and static balance evaluation, cerebellar tests and vectoelectronystagmographic evaluation.

Study design

Clinical prospective.

Results

Alteration in the vectoelectronystagmographic evaluation were found in 36.84% (n=7) Type 1 Diabetes mellitus individuals, being 21.06% (n=4) Peripheral Deficiency Vestibular Syndrome and 15.79% (n=3) Peripheral Irritative Vestibular Syndrome.

Conclusion

We conclude that Type 1 Diabetes mellitus individuals can have their vestibular organ affected, even if there are no otoneurologic complaints.

Labirintopatia secundária aos distúrbios do metabolismo do açúcar: realidade ou fantasia?

As vestibulopatias atribuídas aos distúrbios do metabolismo do açúcar são ainda hoje um tema controverso na literatura pela falta de demonstração objetiva que relacione causa e efeito. OBJETIVO: Nosso objetivo é relatar os resultados seriados do Teste de Integração Sensorial no acompanhamento dos pacientes portadores de DMA tratados com dieta fracionada e restrição de glicose. FORMA DE ESTUDO: Retrospectivo, inclui um desenho de descrição de casos. MÉTODO: Foram avaliadas as respostas de 21 pacientes portadores de distúrbios do metabolismo do açúcar e tontura submetidos à dieta fracionada com restrição de glicose. A medição objetiva do equilíbrio corporal dos pacientes foi feita pela Posturografia Dinâmica Computadorizada, utilizando-se o protocolo do Teste de Integração Sensorial. RESULTADOS: Após a instituição da dieta, observou-se melhora objetiva significante nas condições que retratam a função vestibular e o equilíbrio corporal dos indivíduos estudados. CONCLUSÃO: Concluímos que o Teste de Integração Sensorial demonstrou ser uma ferramenta útil na documentação da melhora do equilíbrio corporal de pacientes portadores de DMA submetidos à dieta fracionada com restrição de glicose.

Prevalência das alterações metabólicas em pacientes portadores de queixas vestibulares

FORMA DE ESTUDO: Clínico prospectivo. MATERIAL E MÉTODO: Os autores avaliam a prevalência de alterações metabólicas em 325 pacientes que procuraram o Setor de Otoneurologia do Hospital das Clínicas da FMUSP com queixas vestibulares. Os pacientes foram consecutivamente atendidos entre janeiro de 1997 e janeiro de 2002. Foram avaliados os primeiros exames referentes ao protocolo clássico de investigação das tonturas, que compreende a dosagem de LDL colesterol, TSH, T3 e T4 e glicemia de jejum. As alterações encontradas foram então comparadas às observadas na população geral. As alterações mais significativas encontradas foram a elevação dos níveis de LDL colesterol, a presença de níveis alterados de hormônios tireoideanos e a maior freqüência do diabetes mellitus na população estudada. CONCLUSÃO: Conclui-se que é válida a investigação destes dados, visto que são mais freqüentes na população de risco e que a correta abordagem dessas alterações melhora o prognóstico e o controle da tontura.

Stimulus and recording variables and their effects on mammalian vestibular evoked potentials

Linear vestibular evoked potentials (VsEPs) measure the collective neural activity of the gravity receptor organs in the inner ear that respond to linear acceleration transients. The present study examined the effects of electrode placement, analog filtering, stimulus polarity and stimulus rate on linear VsEP thresholds, latencies and amplitudes recorded from mice. Two electrode-recording montages were evaluated, rostral (forebrain) to 'mastoid' and caudal (cerebellum) to 'mastoid'. VsEP thresholds and peak latencies were identical between the two recording sites; however, peak amplitudes were larger for the caudal recording montage. VsEPs were also affected by filtering. Results suggest optimum high pass filter cutoff at 100-300 Hz, and low pass filter cutoff at 10,000 Hz. To evaluate stimulus rate, linear jerk pulses were presented at 9.2, 16, 25, 40 and 80 Hz. At 80 Hz, mean latencies were longer (0.350-0.450 ms) and mean amplitudes reduced (0.8-1.8 microV) for all response peaks. In 50% of animals, late peaks (P3, N3) disappeared at 80 Hz. The results offer options for VsEP recording protocols.

Pesquisa do nistagmo/vertigem de posição e avaliação eletronistagmográfica em um grupo de indivíduos portadores de diabetes Mellitus tipo I

Introdução: De acordo com a Sociedade Brasileira de Diabetes, estima-se que existam no Brasil cerca de 5 milhões de pessoas com a patologia. No estado do Rio Grande do Sul há, provavelmente, 400.000 pacientes diabéticos23,27. Dentre as alterações que os indivíduos portadores de diabetes Mellitus podem apresentar, estão incluídos os distúrbios vestibulares. Objetivo: O presente trabalho teve por objetivo colaborar nas pesquisas de melhoria na qualidade de vida do paciente diabético e realizar pesquisa do nistagmo/ vertigem de posição e eletronistagmografia, a fim de identificar possíveis alterações. Forma de estudo: Clínico prospectivo. Material e método: 12 indivíduos portadores de diabetes Mellitus tipo I, usuários regulares de insulina, com idades entre 12 e 27 anos e componentes da Associação Riograndense de Apoio aos Diabéticos (ARAD). Para verificar as respostas vestibulares nos indivíduos portadores de diabetes Mellitus tipo I, foram realizados anamnese específica, meatoscopia, timpanometria, pesquisa do nistagmo/ vertigem de posição e eletronistagmografia na amostra selecionada. Resultados: Verificou-se Síndrome Vestibular Periférica Irritativa em 75% dos resultados alterados. Destes, 62,5% se tratavam de sujeitos sem queixa otoneurológica. Conclusões: Observou-se que o efeito do diabetes tipo I, na função vestibular, deve ser avaliado como as demais complicações diabéticas usuais, mesmo em pacientes assintomáticos, pois, com o diagnóstico etiológico precoce, é possível o auxílio na prevenção das complicações desta patologia.