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

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 impact of vestibular dysfunction on falls and postural instability in individuals with type 2 diabetes with and without diabetic polyneuropathy

Aim

This study aimed to determine the association between vestibular dysfunction, falls, and postural instability in individuals with type 2 diabetes (T2D) compared to healthy control individuals and to examine the impact of diabetic polyneuropathy (DPN).

Methods

This cross-sectional study included individuals with T2D with DPN (n = 43), without DPN (n = 32), and healthy controls (n = 32). Cervical and ocular vestibular evoked myogenic potentials (VEMP) were recorded, and latencies and amplitudes were determined. DPN was diagnosed based on nerve conduction studies and clinical scores. Postural instability was examined using a static posturographic balance system and calculated as an instability index (ST). Falls were recorded retrospectively during the past year. Group comparisons were conducted by using univariate and bivariate statistics.

Results

Individuals with T2D experienced more falls than healthy controls (T2D with DPN n = 12[38%], T2D without DPN n = 15[35%], controls n = 5[16%], p = 0.04). Individuals with T2D had decreased postural stability, T2D with DPN, ST (median of 52[iqi = 33; 77]), T2D without DPN, ST (median of 31[iqi = 24; 39]), controls ST (median of 26[iqi = 19; 33], p = 0.01), when comparing all three groups. Individuals with T2D had a greater number of no-responses in oVEMP compared to controls (T2D with DPN, n = 15[46.9%] T2D without DPN n = 25[58.1%], controls n = 9[28.1%], p = 0.04). No difference was found in cVEMP and oVEMP amplitudes in any of the groups. Irrespectively of DPN, fallers with T2D had decreased oVEMP and cVEMP latencies on the right ears, when comparing to non-fallers, respectively, n10 (fallers [median of 16, iqi=15;19 ms.] vs. non-fallers [median of 25 iqi=16;35 ms]); p13 (fallers [median of 16, iqi=15;17 ms.] vs. non-fallers [median of 15, iqi=8;16 ms.], p < 0.05).

Conclusion

Falls and postural instability were more frequent in individuals with T2D compared to healthy controls. Fallers with T2D had vestibular end-organ impairments based on the oVEMP and cVEMP latencies on the right but not the left ears, irrespective of DPN. Individuals with T2D had more frequent no-response of the oVEMP, indicating impaired vestibular nerve function.

Diet, sex, and genetic predisposition to obesity and type 2 diabetes modulate motor and anxiety-related behaviors in mice, and alter cerebellar gene expression

Obesity and type 2 diabetes (T2D) are serious health problems linked to neurobehavioral alterations. We compared motor function, anxiety-related behavior, and cerebellar gene expression in TALLYHO/Jng (TH), a polygenic model prone to insulin resistance, obesity, and T2D, and normal C57BL/6 J (B6) mice. Male and female mice were weaned onto chow or high fat (HF) diet at 4 weeks of age (wk), and experiments conducted at young (5 wk) and old (14 - 20 wk) ages. In the open field, distance traveled was significantly lower in TH (vs. B6). For old mice, anxiety-like behavior (time in edge zone) was significantly increased for TH (vs B6), females (vs males), and for both ages HF diet (vs chow). In Rota-Rod testing, latency to fall was significantly shorter in TH (vs B6). For young mice, longer latencies to fall were observed for females (vs males) and HF (vs chow). Grip strength in young mice was greater in TH (vs B6), and there was a diet-strain interaction, with TH on HF showing increased strength, whereas B6 on HF showed decreased strength. For older mice, there was a strain-sex interaction, with B6 males (but not TH males) showing increased strength compared to the same strain females. There were significant sex differences in cerebellar mRNA levels, with Tnfα higher, and Glut4 and Irs2 lower in females (vs males). There were significant strain effects for Gfap and Igf1 mRNA levels with lower in TH (vs B6). Altered cerebellar gene expression may contribute to strain differences in coordination and locomotion.

Arterial stiffness and augmentation index are associated with balance function in young adults

OBJECTIVE

Arterial stiffness and pulsatile central hemodynamics have been shown to affect various aspects of physical function, such as exercise capacity, gait speed, and motor control. The aim of this study was to examine the potential association between arterial stiffness and balance function in healthy younger men and women.

METHODS

112 participants (age = 21 ± 4 years, n = 78 women) underwent measures of arterial stiffness, pulsatile central hemodynamics, balance function and physical fitness in this cross-sectional study. Postural sway was measured in triplicate while participants stood on a foam surface with their eyes closed for 20 s. The average total center of pressure path length from the three trials was used for analysis. Measures of vascular function were estimated using an oscillometric blood pressure device while at rest and included pulse wave velocity (PWV), augmentation index (AIx), and pulse pressure amplification. Measures of physical fitness used as covariates in statistical models included handgrip strength determined from a handgrip dynamometer, lower-body flexibility assessed using a sit-and-reach test, estimated maximal aerobic capacity (VO₂max) using heart rate and a step test, and body fat percentage measured from air displacement plethysmography.

RESULTS

The results from linear regression indicated that after considering sex, mean arterial pressure, body fat, estimated VO₂max, handgrip strength, and sit-and-reach, PWV (β = 0.44, p < 0.05) and AIx (β = - 0.25, p < 0.01) were significant predictors of postural sway, explaining 10.2% of the variance.

CONCLUSION

Vascular function is associated with balance function in young adults independent of physical fitness. Increased arterial stiffness may negatively influence balance, while wave reflections may be protective for balance.

Reliability and learning effects of repeated exposure to the Bertec Balance Advantage sensory organisation test in healthy individuals

BACKGROUND

The Sensory Organisation Test (SOT) of computerised dynamic posturography (CDP) is a well-established clinical test used to measure postural control. Advances in technology have enabled new CDP systems to use immersive virtual reality, such as the Bertec® Balance Advantage®. While the Bertec provides an innovative approach to posturography, the reliability and learning effects of the Bertec in administering the SOT has not been thoroughly investigated.

RESEARCH QUESTION

To evaluate the reliability and performance during repeated administration of the Bertec® Balance Advantage® SOT.

METHODS

Fourteen healthy adults (age 27.17 ± 5.5years; 10 females) participated. Each participant performed five SOTs over three sessions. The first two sessions were approximately two days apart and the third one month later. In the first two sessions, two SOTs were conducted, and in the third session, one was performed. Composite, equilibrium, and ratio scores were used for analysis.

RESULTS

Poor within-session reliability was found in the first session for the composite score (ICC: 0.73, 95% CI: 0.32-0.91), which improved by the second session (ICC: 0.84, 95% CI: 0.58-0.94). Poor within-session reliability (ICC <0.5) was found for all ratio and equilibrium scores, except for the equilibrium score of condition 3, which demonstrated moderate reliability (ICC: 0.84, 95% CI: 0.57-0.95). Poor between-session reliability was found for all outcomes. There was an increase in the composite and equilibrium scores for conditions 5 and 6 over the 5 tests, which plateaued after the fourth test, and were retained at 1 month.

SIGNIFICANCE

The data demonstrate a steady increase in performance with repeated exposure to the Bertec SOT, which was maintained one month later, indicating a learning effect. We recommend that a minimum of two familiarisation sessions should be administered to establish baseline performance and improve reliability.

Relationship Between Chronic Conditions and Balance Disorders in Outpatients with Dizziness: A Hospital-Based Cross-Sectional Study

Background

Balance dysfunction is common in adult outpatients with dizziness, especially those who are older, which can lead to catastrophic outcomes such as falls. The aim of this study was to investigate the association between chronic conditions and balance disorders in patients with dizziness, especially those who are elderly.

Material/Methods

A cross-sectional study was conducted in adult outpatients diagnosed with dizziness referred to the Department of Otolaryngology at Beijing Tongren Hospital from September 2017 to August 2018. All of the patients completed a self-administered, structured questionnaire. Demographic data and information on history of chronic conditions were collected and the patients were divided into 2 groups based on whether their balance was normal or abnormal.

Results

Three hundred and thirty-two patients were included in this study, 168 in the normal balance group and 164 in the abnormal balance group. The incidence of chronic conditions, including hypertension and diabetes, in the abnormal balance group was higher than that in the normal balance group (all P<0.05). In subgroup analysis based on age, in those who were aged ≥60 years, the prevalence of chronic diseases was higher in the abnormal balance group than in the normal balance group (P=0.002), while there was no difference in age between the groups with abnormal and normal balance. Hypertension (OR: 2.268; 95%CI: 1.038–4.957; P<0.05) was a risk factor for balance disorders in elderly patients rather than those who were younger (P>0.05).

Conclusions

Our results show that chronic conditions are associated with balance function in older patients with dizziness. Thus, specialists should consider chronic conditions, especially hypertension, in elderly patients with dizziness.