The use of dynamic posturography to detect neurosensorial disorder in IDDM without clinical neuropathy

Young type 1 diabetes subjects sway more than healthy persons when somatosensory system is challenged in static standing postural stability tests

In type 1 diabetes, it is important to prevent diabetes-related complications and postural instability may be one clinically observable manifestation early on. This study was set to investigate differences between type 1 diabetics and healthy controls in variables of instrumented posturography assessment to inform about the potential of the assessment in early detection of diabetes-related complications. Eighteen type 1 diabetics with no apparent complications (HbA1c = 58 ± 9 mmol/L, diabetes duration = 15 ± 7 years) and 35 healthy controls underwent six 1-min two feet standing postural stability tests on a force plate. Study groups were comparable in age and anthropometric and performed the test with eyes open, eyes closed (EC), and EC head up with and without unstable padding. Type 1 diabetics exhibited greater sway (path length, p = 0.044 and standard deviation of velocity, p = 0.039) during the EC test with the unstable pad. Also, power spectral density indicated greater relative power (p = 0.043) in the high-frequency band in the test with EC head up on the unstable pad and somatosensory activity increased more (p = 0.038) when the unstable pad was added to the EC test. Type 1 diabetes may induce subtle changes in postural control requiring more active balancing when stability is challenged. Postural assessment using a portable easy-to-use force plate shows promise in detecting a diabetes-related decline in postural control that may be used as a sensitive biomarker of early-phase diabetes-related complications.

Effect of joint limitation and balance control on gait changes in diabetic peripheral neuropathy

Aims

This study analyzed the gait patterns of diabetic peripheral neuropathy (DPN) patients and changes in the center of mass sway to prevent the formation and recurrence of foot ulcers.

Methods

Forty-two subjects were divided into the diabetes mellitus (DM), DPN, and diabetic foot ulcer (DFU) groups. We measured the range of motion (ROM) of the lower limb joints in the resting position and the center of mass sway in the standing position. Joint angles, ROM during walking, and distance factors were evaluated.

Results

In the DFU group, ROM limitation during walking was detected at the knee joint, and functional and ROM limitations were found at the ankle joint. The step length ratio and step width in the DFU group were significantly lower and higher than those in the DM group, respectively. The sway distances in the DFU group were greater than those in the DM and DPN groups.

Conclusions

Functional joint limitations and gait changes due to the decreased ability to maintain the center of gravity were observed in the DFU group. As DPN progressed, the patients' gait became small, wide, and shuffled. Thus, supporting joint movement during walking may help reduce the incidence and recurrence of foot ulcers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13340-023-00647-9.

Age- and gender-specific normative data on computerized dynamic posturography in a cohort of Danish adults

PURPOSE

Balance performance can be measured with a computerized dynamic posturography (CDP). Frequently used CDP protocols include the sensory organization test (SOT), motor control test (MCT) and adaptation test (ADT). The primary aim of this study was to produce normative data using the Bertec^® Balance Advantage CDP on a cohort of healthy adults aged 20-79 years for the SOT, MCT and ADT. The secondary aim was to determine age- and gender-related differences.

METHODS

The study population of 120 participants were divided into age groups of 20-29, 30-39 years, etc., with an equal number of men and women in each group. Using the Bertec^® CDP, the SOT, MCT and ADT protocols were performed.

RESULTS

SOT found that the 70-79 age group and men scored lower equilibrium scores (ES) on SOT4, and SOT6. Women had higher ES on SOT1. For the MCT, backward translation_. latencies were higher for the 60 s and 70 s age groups. The 60 s age group had higher forward translation latencies. Women had lower latencies on all MCTs. For the ADT toes up test, the 70-79 age group scored higher sway energy. On the toes down test, higher sway energy was registered for the 50-79 age groups. Women had lower sway energy for both ADT's.

CONCLUSION

We have produced normative data for healthy adults aged 20-79 years for the SOT, MCT and ADT protocols using the Bertec® Balance Advantage CDP. Balance performance differences might be due to decline in visual acuity, presbyvestibulopathy and differences in body composition.

Association between 30-s Chair Stand-Up Test and Anthropometric Values, Vibration Perception Threshold, FHSQ, and 15-D in Patients with Type 2 Diabetes Mellitus

Simple Summary

Type 2 diabetes mellitus is a chronic global disease with a series of complications that lead to problems in the somatosensory system, the cardiovascular system, health-related quality of life, foot health, and even balance. These balance problems arise from deficits in lower limb strength, among other causes. The 30-s chair stand-up test is a test that evaluates leg strength and is an easy, quick, inexpensive, and predictive test of different parameters. How this test relates to health-related quality of life, vibration sensitivity threshold, and foot health has not been studied. This study tests the degree of the relationships of the 30-s chair stand-up test with the 15-dimensional (15-D) questionnaire, Foot Health Status Questionnaire (FHSQ), vibration sensitivity threshold, and body composition questionnaires.

Abstract

Background: Type 2 diabetes mellitus (T2DM) is a chronic, worldwide disease affecting more than 400 million people. This pathology involves several associated problems, such as diabetic neuropathy complications, obesity, and foot problems, both in terms of health and sensitivity. Objective: The objective of this study was to explore the relationships of the 30-s chair stand-up test with the Foot Health Status Questionnaire (FHSQ), the vibration perception threshold (VPT), and the 15-dimensional (15-D) questionnaire in T2DM people. Methodology: Ninety participants with T2DM were assessed in terms of fat mass percentage, VPT, foot health, health-related quality of life (HRQoL), and the 30-s chair stand-up test. Results: The 30-s chair stand-up test was found to exhibit a moderate relationship with “physical activity” (rho = 0.441; p ≤ 0.001) and “vigor” (rho = 0.443; p ≤ 0.001) from FHSQ. The 30-s chair stand-up test was also found to be weakly associated with foot pain (rho = 0.358; p = 0.001), 15-D total score (rho = 0.376; p ≤ 0.001), “sleeping” (rho = 0.371; p < 0.001), and “depression” (rho = 0.352; p = 0.001). Conclusions: The 30-s chair stand-up test is associated with “physical activity”, “vigor”, and “foot pain” from the FHSQ and the 15-D questionnaire total score and its dimensions “sleeping” and “depression” in type 2 diabetes mellitus patients. Therefore, following the results obtained, qualified clinicians can use the 30-s chair stand-up test as a good tool for monitoring and managing type 2 diabetes.

Standing Balance Performance and Knee Extensors' Strength in Diabetic Patients with Neuropathy

Diabetes peripheral neuropathy (DPN) leads to balance impairment among diabetes mellitus (DM). The aims of this study were to (1) distinguish between DM patients who have/do not have DPN and to (2) compare quadriceps' strength and balance performance of DM, DPN, and healthy groups. Fifteen healthy females and 33 females with type 2 diabetic patients participated. The electrodiagnostic method was used to classify diabetic patients into DM and DPN. A dynamometer was used to measure quadriceps' strength. Single-leg standing on a force plate was also used to quantify participants' balance. Smaller conduction velocity and amplitude and greater distal latency of all nerves were observed in the DPN compared with the DM in particular for sensory nerve. In DPN, conduction velocity was asymmetrical. The quadriceps' strength of both legs in DPN and the right leg in DM was smaller than in the control group. The root mean square of the center of pressure was similar between DM and DPN. But it was larger in DPN than in the control group. DPN is associated with asymmetrical conduction velocity, smaller quadriceps' strength, and weaker balance performance that is suggestive of higher risk of falling. Balance training is recommended for the DPN group during their rehabilitation to reduce their falling risk.

A new approach to characterize postural deficits in chemotherapy-induced peripheral neuropathy and to analyze postural adaptions after an exercise intervention

Background

Postural instability presents a common and disabling consequence of chemotherapy-induced peripheral neuropathy (CIPN). However, knowledge about postural behavior of CIPN patients is sparse. With this pilot study, we used a new approach to i) characterize postural impairments as compared to healthy subjects, ii) allocate possible abnormalities to a set of parameters describing sensorimotor function, and iii) evaluate the effects of a balance-based exercise intervention.

Methods

We analyzed spontaneous and externally perturbed postural control in eight CIPN patients before and after a balance-based exercise intervention by using a modification of an established postural control model. These findings were compared to 15 matched healthy subjects.

Results

Spontaneous sway amplitude and velocity were larger in CIPN patients compared to healthy subjects. CIPN patients’ reactions to external perturbations were smaller compared to healthy subjects, indicating that patients favor vestibular over proprioceptive sensory information. The balance-based exercise intervention up-weighted proprioceptive information in patients.

Conclusions

CIPN patients’ major postural deficit may relate to underuse of proprioceptive information that results in a less accurate posture control as spontaneous sway results indicate. The balance-based exercise intervention is able to partially correct for this abnormality. Our study contributes to a better understanding of postural impairments in CIPN patients and suggests an effective treatment strategy.

Trial registration

German Clinical Trials Register: DRKS00004340, retrospectively registered 04 January 2013.

Quiet standing: The Single Inverted Pendulum model is not so bad after all

In the study of balance and postural control the (Single) Inverted Pendulum model (SIP) has been taken for a long time as an acceptable paradigm, with the implicit assumption that only ankle rotations are relevant for describing and explaining sway movements. However, more recent kinematic analysis of quiet standing revealed that hip motion cannot be neglected at all and that ankle-hip oscillatory patterns are characterized by complex in-phase and anti-phase interactions, suggesting that the SIP model should be substituted by a DIP (Double Inverted Pendulum) model. It was also suggested that DIP control could be characterized as a kind of optimal bi-axial active controller whose goal is minimizing the acceleration of the global CoM (Center of Mass). We propose here an alternative where active feedback control is applied in an intermittent manner only to the ankle joint, whereas the hip joint is stabilized by a passive stiffness mechanism. The active control impulses are delivered to the ankle joint as a function of the delayed state vector (tilt rotation angle + tilt rotational speed) of a Virtual Inverted Pendulum (VIP), namely a pendulum that links the ankle to the CoM, embedded in the real DIP. Simulations of such DIP/VIP model, with the hybrid control mechanism, show that it can reproduce the in-phase/anti-phase interaction patterns of the two joints described by several experimental studies. Moreover, the simulations demonstrate that the DIP/VIP model can also reproduce the measured minimization of the CoM acceleration, as an indirect biomechanical consequence of the dynamic interaction between the active control of the ankle joint and the passive control of the hip joint. We suggest that although the SIP model is literally false, because it ignores the ankle-hip coordination, it is functionally correct and practically acceptable for experimental studies that focus on the postural oscillations of the CoM.

Adaptation of perturbation to postural control in individuals with diabetic peripheral neuropathy

Loss of sensation in the feet due to diabetic peripheral neuropathy can cause deterioration of postural control and result in higher risk of trips, slips or falls. In the literature, many studies have reported that people with diabetic peripheral neuropathy tend to show greater displacement of body sway than normal people when the base of support is disrupted. But not much is known about postural characteristics of diabetics with peripheral neuropathy at the moment of postural stability disruptions and during the time span for recovering stability. The objective of this study was to analyze differences of postural characteristics between diabetics with peripheral neuropathy and diabetics without peripheral neuropathy. A learning effect of perturbation was found for the diabetic peripheral neuropathy group in the posterior direction of perturbation during the first phase, which may indicate that it could be possible to design a postural control program for those people.

Postural sway in individuals with type 2 diabetes and concurrent benign paroxysmal positional vertigo

BACKGROUND AND PURPOSE

diabetes has been shown to affect the peripheral vestibular end organs and is associated with an increase in the frequency of benign paroxysmal positional vertigo (BPPV). People with diabetes have higher postural sway; however, the impact of symptomatic BPPV on postural sway in individuals with diabetes is unclear. The purpose of this cross-sectional study was to examine postural sway in people with type 2 diabetes who have symptomatic, untreated BPPV (BPPVDM).

METHODS

fifty-two participants (mean age 56.9 ± 5.6 years) were enrolled: controls (n = 14), diabetes (n = 14), BPPV only (n = 13) and BPPVDM (n = 11). An inertial motion sensor was used to detect pelvic acceleration across five standing conditions with eyes open/closed on firm/foam surfaces. Range of acceleration (cm/s²), peak velocity (cm/s) and variability of sway [root mean square (RMS)] in the anterior-posterior (AP) and medial-lateral (ML) directions were used to compare postural sway between groups across conditions.

RESULTS

participants with BPPVDM had higher ranges of acceleration in the AP (p = 0.02) and ML (p = 0.02) directions, as well as higher peak velocity (p < 0.001) and RMS values (p = 0.006) in the AP direction compared to the control and diabetes groups. Standing on foam with eyes closed and tandem stance were challenging conditions for people with BPPVDM.

CONCLUSION

clinicians may consider using standing on foam with eyes closed and tandem standing with eyes open to assess postural control in people with BPPVDM to identify postural instability.

Effect of twelve-month physical exercise program on patients with osteoporotic vertebral fractures: a randomized, controlled trial

We performed a randomized clinical trial to evaluate the effect of a 12-month physical exercise program on quality of life, balance, and functional mobility in postmenopausal women with osteoporotic vertebral fractures. All three outcomes improved in the intervention group and were better than in the controls.

INTRODUCTION

Th aim of this study was to evaluate the effectiveness of a structured physical exercise intervention on quality of life, functional mobility, and balance in patients with osteoporotic vertebral fractures and back pain.

METHODS

Seventy-eight postmenopausal women with vertebral fractures were randomized into an exercise group (n = 40) and a control group (n = 38). The mean age was 69.2 ± 7.7 years. All women had at least one osteoporotic vertebral fracture and suffered from chronic back pain. Patients with a history of vertebral and non-vertebral fracture within the past 6 months were excluded. The 40-min exercise program was conducted twice weekly for 1 year. Participants in the control group were instructed to continue their usual daily activities. Participants were assessed at baseline and at 12 months using the Quality of Life Questionnaire (QUALEFFO-41). Balance was measured with the Balance Master® System NeuroCom® and functional mobility was measured with the "timed up and go" test and "sit-to-stand" test.

RESULTS

Total QUALEFFO-41 score after 12 months was significantly better in the exercise group (44.2 ± 7.5) compared to the control group (56.6 ± 9.4), p < 0.0001. Quality of life improved in domains: "Pain", "Physical function: Jobs around the house", "Physical function: Mobility", "Social function", "General health perception" in the exercise group as compared to the control group. After 12 months, balance as assessed by "Tandem Walk and Sway" became significantly better in the exercise group as compared to the control group (p = 0.02). A significant improvement in the "timed up and go" test (p = 0.02) and the "sit-to-stand" test (p = 0.01) was shown in the exercise group compared to the control group.

CONCLUSIONS

This is the first 12 month-randomized clinical trial of exercise in osteoporotic women with a vertebral fracture that demonstrates improvement of three key outcome measures: quality of life, functional mobility, and balance.

Effects of a Novel Therapeutic Intervention in Patients With Diabetic Peripheral Neuropathy

OBJECTIVE

To determine the effect of a novel therapeutic intervention called intraneural facilitation on balance measures and a neuropathy scale in patients with diabetic peripheral neuropathy.

DESIGN

Prospective pre- and posttest, single group clinical trial.

SETTING

Outpatient physical therapy clinic.

PARTICIPANTS

Patients with diabetic peripheral neuropathy (N=13).

INTERVENTION

Subjects received 10 sessions of intraneural facilitation.

MAIN OUTCOME MEASURES

The modified Total Neuropathy Scale, the NeuroCom SMART Balance Master system computerized dynamic posturography (CDP) that includes the Sensory Organization Test (SOT) and the limits of stability (LOS), and the Activities-specific Balance and Confidence (ABC) scale.

RESULTS

Subjects in this study showed significant improvement in the modified Total Neuropathy Scale, SOT, and 1 component in the LOS test (movement velocity). There were no significant differences in the ABC scale or in 4 components of the LOS test, which were reaction time, end point excursion, maximum excursion, and directional control.

CONCLUSIONS

Intraneural facilitation improved objective balance measures and neuropathy symptoms in patients with diabetic peripheral neuropathy. Further study is needed to determine long-term benefits of this intervention.

Quantitative assessment of early biomechanical modifications in diabetic foot patients: the role of foot kinematics and step width

BACKGROUND

Forefoot ulcers (FU) are one of the most disabling and relevant chronic complications of diabetes mellitus (DM). In recent years there is emerging awareness that a better understanding of the biomechanical factors underlying the diabetic ulcer could lead to improve the management of the disease, with significant socio-economic impacts. Our purpose was to try to detect early biomechanical factors associated with disease progression.

METHODS

Thirty subjects (M/F: 22/8; mean age ± SD: 61,84 ± 10 years) with diagnosis of type II DM were included. The participants were divided into 3 groups (10 subjects per group) according to the stage of evolution of the disease: Group 1, subjects with newly diagnosed type II DM, without clinical or instrumental diabetic peripheral neuropathy (DPN) nor FU (group called "DM"); Group 2, with DPN but without FU (group called "DPN"); Group 3, with DPN and FU (group called "DNU"). All subjects underwent 3-D Gait Analysis during walking at self-selected speed, measuring spatio-temporal, kinematic and kinetic parameters and focusing on ankle and foot joints. The comparative analysis of values between groups was performed using 1-way ANOVA. We also investigated group to group differences with Tukey HSD test. The results taken into consideration were those with a significance of P < 0,05. 95 % confidence interval was also calculated.

RESULTS

A progressive and significant trend of reduction of ROM in flexion-extension of the metatarso-phalangeal joint (P = 0.0038) and increasing of step width (P = 0.0265) with the advance of the disease was evident, with a statistically significant difference comparing subjects with recently diagnosed diabetes mellitus and subjects with diabetic neuropathy and foot ulcer (P = 0.0048 for ROM and P = 0.0248 for step width at Tukey's test).

CONCLUSIONS

The results provide evidence that foot segmental kinematics, along with step width, can be proposed as simple and clear indicators of disease progression. This can be the starting point for planning more targeted strategies to prevent the occurrence and the recurrence of a FU in diabetic subjects.

Characterization of Vestibulopathy in Individuals with Type 2 Diabetes Mellitus

Objective

Previous observational studies suggest higher rates of vestibular dysfunction among patients with type 2 diabetes mellitus (DM) compared with those without diabetes. This study aims to functionally localize vestibular dysfunction in adults with type 2 DM.

Study Design

Prospective cohort study.

Setting

Tertiary academic medical center.

Subjects and Methods

Adults 50 years of age and older with ≥10-year history of type 2 DM were recruited (December 2011–February 2013, n = 25). Vestibular function was assessed by cervical and ocular vestibular-evoked myogenic potentials (VEMPs), testing the saccule and utricle, respectively. Head thrust dynamic visual acuity testing assessed semicircular canal (SCC) function in all canal planes. Results were compared with nondiabetic age-matched controls (n = 25).

Results

Subjects were 64.7 ± 7.6 years old, were 40% female, and had a mean hemoglobin A1c of 8.3% ± 1.7%. SCC dysfunction was more common than otoconial organ dysfunction, with 70% of subjects with DM demonstrating impaired performance of at least 1 SCC (ΔlogMAR ≥0.18) and 50% demonstrating otoconial organ impairment (absent ocular VEMP and/or cervical VEMP). Adults with type 2 DM had poorer lateral and superior SCC performance ( P < .05) but similar posterior SCC performance compared with controls ( P = .16). Both cervical VEMP peak-to-peak amplitude and ocular VEMP n1 amplitude were also decreased with diabetes ( P < .01).

Conclusion

Adults with type 2 DM have poorer performance on tests of vestibular function related to both SCC and otoconial organ function compared with nondiabetic age-matched adults. Future studies are needed to better understand the relationship between vestibular function and functional disability in persons with diabetes.

Effect of surgical decompression of nerves in the lower extremity in patients with painful diabetic polyneuropathy on stability: a randomized controlled trial

OBJECTIVE

To investigate the effect of decompression of nerves in the lower extremity in patients with painful diabetic polyneuropathy on static balance using a sensitive pressure mat system.

DESIGN

Non-blinded randomized controlled trial.

SETTING

Single center study performed at the University Medical Center Utrecht between 2010-2013.

SUBJECTS

Patients with painful diabetic polyneuropathy assessed with the Diabetic Neuropathy Symptom score and Diabetic Neuropathy Examination between 18-90 years. Exclusion criteria were: physical problems leading to instability, BMI>35 kg/m2, ankle fractures in history, amputations proximal to the tarsometatarsal joints, active foot ulcer(s), severe occlusive peripheral vascular diseases.

INTERVENTION

Unilateral surgical nerve decompression at four sites in the lower extremity, the contralateral limb was used as control (within-patient comparison), with one year follow-up.

MAIN MEASURES

Preoperatively and 6 and 12 months postoperatively, weight bearing and five variables of sway of the center of pressure were measured with a pressure mat with eyes open and eyes closed. T-test was used for evaluation of postoperative results.

RESULTS

Thirty-nine Patients met inclusion criteria and were enrolled for stability testing. Postoperatively no significant differences for sway variables and weight bearing were seen compared to preoperatively measurements.

CONCLUSIONS

There is no evidence that surgical decompression of nerves of the lower extremity influences stability within one year after surgery in patients with painful diabetic polyneuropathy.

Computerized Dynamic Posturography in Patients with Diabetic Peripheral Neuropathy and Visual Feedback-Based Balance Training Effects

BACKGROUND: Diabetic peripheral neuropathy (DPN) often has reduced stability during standing conditions.AIM: To compare balance control in diabetic patients and normal subjects using computerized dynamic posturography and to assess effect of visual feedback-based balance training in DPN.MATERIALS AND METHODS: A total of 57 patients of type 2 diabetes mellitus and 30 age-matched normal control subjects were recruited. The sensory organization test was done before and after the training program.RESULTS: There was a significant decrease of mean (± SD) of composite equilibrium score and somatosensory ratio score between subgroups of DPN and control healthy group (p < 0.05).  There was a significant increase of mean (± SD) of composite equilibrium score and the somatosensory ratio score after treatment as compared to results before training (p < 0.05) in mild DPN.  Moreover, there were a significant correlation between composite equilibrium score and disease duration before training in the severe DPN (r = 0.368, p < 0.05). CONCLUSIONS: Computerized dynamic posturography is an important quantitative tool in the assessment of posture instability and allows for early disclosure of the failure of the postural control system. Visual feedback-based balance training was shown to be a promising method for fall prevention among early diabetes mellitus with peripheral neuropathy.

Diabetic foot and exercise therapy: step by step the role of rigid posture and biomechanics treatment

Lower extremity ulcers represent a serious and costly complication of diabetes mellitus. Many factors contribute to the development of diabetic foot. Peripheral neuropathy and peripheral vascular disease are the main causes of foot ulceration and contribute in turn to the growth of additional risk factors such as limited joint mobility, muscular alterations and foot deformities. Moreover, a deficit of balance, posture and biomechanics can be present, in particular in patients at high risk for ulceration. The result of this process may be the development of a vicious cycle which leads to abnormal distribution of the foot's plantar pressures in static and dynamic postural conditions. This review shows that some of these risk factors significantly improve after a few weeks of exercise therapy (ET) intervention. Accordingly it has been suggested that ET can be an important weapon in the prevention of foot ulcer. The aim of ET can relate to one or more alterations typically found in diabetic patients, although greater attention should be paid to the evaluation and possible correction of body balance, rigid posture and biomechanics. Some of the most important limitations of ET are difficult access to therapy, patient compliance and the transitoriness of the results if the training stops. Many proposals have been made to overcome such limitations. In particular, it is important that specialized centers offer the opportunity to participate in ET and during the treatment the team should work to change the patient's lifestyle by improving the execution of appropriate daily physical activity.

Audiovestibular functions in noninsulin-dependent diabetes mellitus

CONCLUSION

This study supports the proposition that vestibular dysfunction and sensorineural hearing loss (SNHL) may be considered among the complications due to noninsulin-dependent diabetes mellitus (NIDDM).

OBJECTIVE

The aim of this study was to evaluate the audiovestibular functions in patients with NIDDM and to determine if there is any correlation between audiovestibular dysfunction and the duration of the disease.

METHODS

A total of 104 patients diagnosed with NIDDM and 104 nondiabetic control subjects made up the study group. Diabetic patients were also divided into subgroups of ≤7 years and >7 years according to the duration of the disease. Pure-tone audiometry (PTA), speech recognition scores (SRS), impedance audiometry, and vestibular function tests (VFT) were performed for all of the patients.

RESULTS

Hearing thresholds in all frequencies (except at 500 Hz for bone conduction) and SRS values were statistically significant in patients with NIDDM and control subjects, but there was no statistically significant difference according to the duration of the disease. Statistically significant alterations were present in VFT in patients with NIDDM compared with the control subjects. In the diabetic group, only failure in the saccade test was statistically significant according to the duration of the disease.

Sharpening the tandem walking test for screening peripheral neuropathy

OBJECTIVE

Few tests of functional motor behavior are useful for rapidly screening people for lower extremity peripheral neuropathy. The goal of this study was to improve the widely used tandem walking (TW) test.

METHODS

We tested "normal" (control) adult and ambulatory patients with peripheral neuropathy (PN) with their eyes open and eyes closed while they performed TW on industrial carpeting in sock-covered feet. Each subject wore a torso-mounted inertial motion unit to measure kinematic data. The data of subjects with PN also were compared with historical data on patients with vestibular impairments.

RESULTS

The normal and PN groups differed significantly on TW and on the number of steps completed. PN and vestibular impairments data also differed significantly on both visual conditions. Kinematic data showed that patients with PN were more unstable than normal patients in the group. For the number of steps taken during the eyes open condition, receiver operating characteristic (ROC) values were only 0.81 and for the number of steps taken during the eyes closed condition, ROC values were 0.88. Although not optimal, this ROC value is better. Sensitivity and specificity at a cutoff of two steps were 0.81 and 0.92, respectively, and at a cutoff of three steps were 0.86 and 0.75, respectively. ROC values for kinematic data were <0.8, and when combined with the ROC value for the number of steps, the total ROC value did not improve appreciably.

CONCLUSIONS

Although not ideal for screening patients who may have PN, counting the number of steps during TW is a quick and useful clinical test. TW is most sensitive to patients with PN when they are tested with eyes closed.

Análise do equilíbrio em pacientes diabéticos por meio do sistema F-Scan e da Escala de Equilíbrio de Berg

INTRODUÇÃO: Uma das complicações mais frequentes do diabetes mellitus (DM) é a neuropatia diabética (ND), que leva a alterações musculoesqueléticas capazes de causar instabilidade postural e risco de quedas. OBJETIVO: Verificar o equilíbrio dos pacientes diabéticos atendidos no setor de fisioterapia. MATERIAIS E MÉTODOS: Foi realizado um estudo transversal com 25 indivíduos diabéticos com idade média de 60,88 ± 9,23 anos, da Clínica-Escola de Fisioterapia da Universidade Católica de Brasília. Observou-se o equilíbrio estático e dinâmico desses pacientes por meio do sistema F-Scan e da escala de equilíbrio de Berg (EEB), respectivamente, além das correlações entre elas. RESULTADOS: Os participantes do estudo não apresentaram risco de cair pela EEB; não houve associações entre EEB e oscilações laterolaterais medidas pelo F-Scan e houve diferenças significativas entre EEB e oscilações anteroposteriores. CONCLUSÃO: Apesar de não serem verificadas alterações do equilíbrio no F-Scan, os indivíduos avaliados encontram-se fora do alto risco de queda, mesmo que a diminuição da sensibilidade tenha gerado uma tendência baixa na pontuação da EEB. A intervenção fisioterapêutica é benéfica para a manutenção e/ou melhora do equilíbrio corporal, reduzindo, assim, o risco de quedas e aumentando a independência nas atividades de vida diária (AVD).

The effect of spinal cord stimulation (SCS) on static balance and gait

OBJECTIVES

To investigate whether spinal cord stimulation (SCS) has a negative effect on static balance and gait, which is implicated by the increased incidence of falls leading to frequently occurring lead migrations.

MATERIALS AND METHODS

A controlled trial is performed with 11 subjects (four female, seven male) with a mean age of 46 years old. A baseline measurement consisting of static balance and gait tests was performed. Within two weeks after implantation of a spinal cord stimulator, subjects performed the same tests with both stimulation switched on and off. Static balance was assessed with eyes open and eyes closed on hard surface and foam surface. The velocity of the center of pressure and weight symmetry were the main outcome parameters. Kinematics and spatiotemporal outcome parameters were used to analyze gait. ANOVAs were used to compare between baseline, stimulation on, and stimulation off.

RESULTS

 Spinal cord stimulation resulted in significant pain relief as scored on a Visual Analog Scale (p < 0.001). Gait width decreased and this change (indicative of improvement in balance) was significant (p = 0.007). No other significant group differences were found between stimulation baseline and post-surgery measurements. SCS did not influence static balance or gait when group effects were analyzed. Four subjects showed significant differences in static balance between stimulation on and off.

CONCLUSIONS

 The lack of group differences in normal gait and static balance cannot explain the increased incidence of falls. However, four subjects showed an effect of SCS on static balance. Further research to clarify why only a part of the subjects experienced balance problems is recommended and assessments of more demanding balance and gait tasks are desirable.

Peripheral neuropathy may not be the only fundamental reason explaining increased sway in diabetic individuals

BACKGROUND

Individuals with diabetic neuropathy sway more than control individuals while standing. This review specifically evaluated whether peripheral sensory neuropathy can be the only fundamental reason accounting for significant increased sway within this population.

METHODS

Twenty-six experimental articles were selected using MEDLINE and reference lists of relevant articles. The articles chosen investigated kinematic data of postural behaviour in controls and individuals with diabetic neuropathy during stance. Results of literature were compared with four expectations related to the peripheral sensory neuropathy fundamental hypothesis.

FINDINGS

Consistent with the peripheral sensory neuropathy hypothesis, the literature showed that individuals with diabetic neuropathy sway more than controls in quiet stance and even more so if their visual or vestibular systems were perturbed. Inconsistent with the hypothesis, individuals with diabetic neuropathy are more destabilised than controls in conditions altering sensation of the feet and legs (standing on a sway-referenced surface).

INTERPRETATION

The review showed that the peripheral sensory neuropathy hypothesis may not be the only fundamental cause accounting for significant increased postural sway in individuals with diabetic neuropathy. Visual impairments and changes in postural coordination may explain the divergence between expectations and results. In order to develop interventions aimed at improving postural control in individuals with diabetic neuropathy, scientific exploration of these new expectations should be detailed. Also at the practical level, the review discussed which additional sensory information - at the level of the hands and feet - may be more beneficial in individuals with diabetic neuropathy to reduce their postural sway.

Association between type 1 diabetes mellitus and deposits in the semicircular canals

OBJECTIVE

To compare the prevalence of cupular and free-floating deposits in the semicircular canals between temporal bones of type 1 diabetes mellitus patients and normal controls.

STUDY DESIGN

Case-control histopathologic human temporal bone study.

SETTING

Otopathology laboratory in a tertiary academic medical center.

SUBJECTS AND METHODS

Twenty-eight temporal bones from 14 patients with type 1 diabetes mellitus and 56 normal temporal bones from 28 age-matched individuals were histopathologically examined. The cupula and lumina of the semicircular canals were examined for evidence of deposits.

RESULTS

The prevalence of cupular and free-floating deposits in the lateral and posterior semicircular canals was significantly higher in type 1 diabetes mellitus patients compared with normal temporal bones (lateral, cupular deposits, odds ratio [OR], 5.47; 95% confidence interval [CI], 1.43 to 21.02; free-floating deposits, OR, 8.25; 95% CI, 2.42 to 27.85; posterior, cupular deposits, OR, 41.73; 95% CI, 5.96 to 275.50; free-floating deposits, OR, 7.44; 95% CI, 1.91 to 28.53). The prevalence of these deposits was associated with the duration of disease rather than with aging.

CONCLUSION

The findings suggest that type 1 diabetes mellitus is associated with cupular and free-floating deposits in the semicircular canals. The patients with type 1 diabetes mellitus with a longer duration of disease have an increased probability of suffering from benign paroxysmal positional vertigo.

Diabetes, vestibular dysfunction, and falls: analyses from the National Health and Nutrition Examination Survey

OBJECTIVE

Patients with diabetes are at increased risk both for falls and for vestibular dysfunction, a known risk factor for falls. Our aims were 1) to further characterize the vestibular dysfunction present in patients with diabetes and 2) to evaluate for an independent effect of vestibular dysfunction on fall risk among patients with diabetes.

STUDY DESIGN

National cross-sectional survey.

SETTING

Ambulatory examination centers.

PATIENTS

Adults from the United States aged 40 years and older who participated in the 2001-2004 National Health and Nutrition Examination Survey (n = 5,86).

INTERVENTIONS

Diagnosis of diabetes, peripheral neuropathy, and retinopathy.

MAIN OUTCOME MEASURES

Vestibular function measured by the modified Romberg Test of Standing Balance on Firm and Compliant Support Surfaces and history of falling in the previous 12 months.

RESULTS

We observed a higher prevalence of vestibular dysfunction in patients with diabetes with longer duration of disease, greater serum hemoglobin A1c levels and other diabetes-related complications, suggestive of a dose-response relationship between diabetes mellitus severity and vestibular dysfunction. We also noted that vestibular dysfunction independently increased the odds of falling more than 2-fold among patients with diabetes (odds ratio, 2.3; 95% confidence interval, 1.1-5.1), even after adjusting for peripheral neuropathy and retinopathy. Moreover, we found that including vestibular dysfunction, peripheral neuropathy, and retinopathy in multivariate models eliminated the significant association between diabetes and fall risk.

CONCLUSION

Vestibular dysfunction may represent a newly recognized diabetes-related complication, which acts as a mediator of the effect of diabetes mellitus on fall risk.

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.

Painful diabetic neuropathy

The podiatric physician often encounters complex painful neuropathies in daily practice. Diabetic neuropathy is one form of chronic neuropathic pain dealt with on a regular basis. The goal of this article is to review the pathophysiology, diagnosis, and treatment options of this complaint. Medical and surgical interventions are discussed, with a clinical emphasis on patient selection and prevention.

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.

Neuropathy: mobility and quality of life

In summary, diabetes is increasingly becoming a disease of elderly people. Some of the under-appreciated complications such as impaired physical functioning, increased risk for falls and fractures need to be more addressed in the future. When evaluating a patient with peripheral neuropathy, it is also important to pay attention to the possibility of deficits in postural stability and lower extremity functioning. Impairments in lower extremity physical functioning are key contributors to loss of physical independence and have a major impact on quality of life. Increasing awareness of disability as a potentially modifiable complication should become a health priority for people with diabetes. Early results of interventions to improve physical functioning are promising and need to be further explored within clinical practice.

Approximate entropy detects the effect of a secondary cognitive task on postural control in healthy young adults: a methodological report

BACKGROUND

Biomechanical measures of postural stability, while generally useful in neuroscience and physical rehabilitation research, may be limited in their ability to detect more subtle influences of attention on postural control. Approximate entropy (ApEn), a regularity statistic from nonlinear dynamics, recently has demonstrated relatively good measurement precision and shown promise for detecting subtle change in postural control after cerebral concussion. Our purpose was to further explore the responsiveness of ApEn by using it to evaluate the immediate, short-term effect of secondary cognitive task performance on postural control in healthy, young adults.

METHODS

Thirty healthy, young adults performed a modified version of the Sensory Organization Test featuring single (posture only) and dual (posture plus cognitive) task trials. ApEn values, root mean square (RMS) displacement, and equilibrium scores (ES) were calculated from anterior-posterior (AP) and medial-lateral (ML) center of pressure (COP) component time series. For each sensory condition, we compared the ability of the postural control parameters to detect an effect of cognitive task performance.

RESULTS

COP AP time series generally became more random (higher ApEn value) during dual task performance, resulting in a main effect of cognitive task (p = 0.004). In contrast, there was no significant effect of cognitive task for ApEn values of COP ML time series, RMS displacement (AP or ML) or ES.

CONCLUSION

During dual task performance, ApEn revealed a change in the randomness of COP oscillations that occurred in a variety of sensory conditions, independent of changes in the amplitude of COP oscillations. The finding expands current support for the potential of ApEn to detect subtle changes in postural control. Implications for future studies of attention in neuroscience and physical rehabilitation are discussed.

Quantitative and Clinical Description of Postural Instability in Women With Breast Cancer Treated With Taxane Chemotherapy

OBJECTIVE

To describe the postural control of women who received taxane chemotherapy for treatment of breast cancer using quantitative and clinically feasible measures.

DESIGN

Prospective descriptive study.

SETTING

University-based comprehensive cancer center.

PARTICIPANTS

Twenty women who completed taxane treatment for breast cancer and 20 healthy controls participated in this study.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Two quantitative measures of postural control were used, Sensory Organization Test (SOT) and center of pressure (COP) velocities. Two clinically feasible measures of postural control were used, the Fullerton Advanced Balance Scale (FABS) and Timed Up & Go (TUG) test.

RESULTS

Compared with healthy controls, women with breast cancer had poorer postural control on all of the outcome measures. FABS and TUG scores correlated moderately with SOT and COP scores.

CONCLUSIONS

After taxane chemotherapy, women with breast cancer show significantly increased postural instability compared with matched controls. Clinically feasible measures of postural control correlated with quantitative tests. These results suggest that these clinical measures may be useful to screen patients to determine who may benefit from rehabilitation.

Postural control following a self-initiated reaching task in type 2 diabetic patients and age-matched controls

Although the postural stability of diabetic patients is affected in the presence of polyneuropathy, it has been suggested that diabetes per se has no effect on balance control during quiet standing. However, recent studies have reported muscular mechanical deficits in patients with type 2 diabetes (T2D) that may be highlighted during a more destabilizing task than quiet standing. Therefore, the objective of this study was to compare non-diabetic and T2D subjects during a modified version of the functional reach (FR) test in order to discriminate differences in postural control associated with diabetes per se. Thirty subjects (15 non-diabetic and 15 T2D) were requested to stand on a force platform and to perform the FR test. Center of pressure velocity (V(COP)), root-mean-square (RMS) amplitude and range of the COP were calculated in the anterior-posterior direction during three specific periods of the FR performance: namely "before", "on-going" and "after". No significant difference between the non-diabetic subjects and the T2D subjects was found for the FR performance. However, T2D subjects had significantly higher V(COP), RMS and range of COP displacements for the "after" period compared to the non-diabetic group (p<0.05). These results suggest that T2D subjects without peripheral neuropathy may have difficulties regaining their stability after a self-initiated reaching task. Therefore, diabetes mellitus per se, could have a direct effect on postural control during standing after a self-induced forward reaching movement.

Video game-based exercises for balance rehabilitation: a single-subject design

OBJECTIVES

To investigate whether coupling foot center of pressure (COP)-controlled video games to standing balance exercises will improve dynamic balance control and to determine whether the motivational and challenging aspects of the video games would increase a subject's desire to perform the exercises and complete the rehabilitation process.

DESIGN

Case study, pre- and postexercise.

SETTING

University hospital outpatient clinic.

PARTICIPANTS

A young adult with excised cerebellar tumor, 1 middle-aged adult with single right cerebrovascular accident, and 1 middle-aged adult with traumatic brain injury.

INTERVENTION

A COP-controlled, video game-based exercise system.

MAIN OUTCOME MEASURES

The following were calculated during 12 different tasks: the number of falls, range of COP excursion, and COP path length.

RESULTS

Postexercise, subjects exhibited a lower fall count, decreased COP excursion limits for some tasks, increased practice volume, and increased attention span during training.

CONCLUSIONS

The COP-controlled video game-based exercise regime motivated subjects to increase their practice volume and attention span during training. This in turn improved subjects' dynamic balance control.

Ankle joint proprioception and postural control in basketball players with bilateral ankle sprains

BACKGROUND

Deficiencies in ankle proprioception and standing balance in basketball players with multiple ankle sprains have been reported in separate studies. However, the question of how ankle proprioceptive inputs and postural control in stance are related is still unclear.

HYPOTHESIS

Ankle repositioning errors and the amount of postural sway in stance are increased in basketball players with multiple ankle sprains.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty healthy male basketball players and 19 male basketball players who had suffered bilateral ankle sprains within the past 2 years were examined. Both groups were similar in age. Passive ankle joint repositioning errors at 5 degrees of plantar flexion were used to test for ankle joint proprioception. The Sensory Organization Test was applied with dynamic posturography to assess postural sway angle under 6 sensory conditions.

RESULTS

A significant increase in ankle repositioning errors was demonstrated in basketball players with bilateral ankle sprains (P < .05). The mean errors in the right and left ankles were increased from 1.0 degrees (standard deviation, 0.4 degrees ) and 0.8 degrees (standard deviation, 0.2 degrees ), respectively, in the healthy players to 1.4 degrees (standard deviation, 0.7 degrees ) and 1.1 degrees (standard deviation, 0.5 degrees ) in the injured group. A significant increase in the amount of postural sway in the injured subjects was also found in conditions 1, 2, and 5 of the Sensory Organization Test (P < .05). Furthermore, there were positive associations between averaged errors in repositioning both ankles and postural sway angles in conditions 1, 2, and 3 of the Sensory Organization Test (r = 0.39-0.54, P < .05).

CONCLUSIONS

Ankle repositioning errors and postural sway in stance increased in basketball players with multiple ankle sprains. A positive relationship was found between these 2 variables.

CLINICAL RELEVANCE

Such findings highlight the need for the rehabilitation of patients with multiple ankle sprains to include proprioceptive and balance training.

Case Report: Painful Peripheral Neuropathy Following Treatment With Docetaxel for Breast Cancer

Peripheral neuropathy is a common side effect of many chemotherapy agents. As many as 60% of patients receiving taxane therapy report symptoms such as numbness, tingling, burning, pain, and, in severe cases, weakness in a stocking and glove pattern. These symptoms are associated with problems in physical mobility and decreased quality of life, yet few articles in the literature discuss collaborative interdisciplinary assessment and treatment of this population. This article describes the care of a patient with diabetes and docetaxel-induced, painful peripheral neuropathy by a multidisciplinary team of nurses, physicians, and physical therapists. Because nurses are often the first clinicians to recognize symptoms of chemotherapy-induced peripheral neuropathy, they provide the essential coordination of care by appropriate medical and rehabilitative services. This case also raises important questions about the relationship between diabetes mellitus and persistent, painful peripheral neuropathy.

Gait characteristics in people with type 2 diabetes mellitus

Sixteen control subjects and 15 subjects with type 2 diabetes were examined to compare gait characteristics during walking in a linear path and in turns of 0.33 and 0.66 m diameter. Subjects were excluded if there was diminished sensation in the feet or impairment of strength in the legs. This was done to isolate the effect of diabetes gait independent of loss of sensation. Gait was assessed through contact sensors on the foot, video, and two axis accelerometers mounted bilaterally on the head, shoulders, hips, knees and ankles. The results of these experiments showed that subjects with diabetes walked significantly slower (P<0.05) than control subjects and with a wider stance (P<0.01), both for walking in a linear path (velocity of subjects with diabetes was 62.2% that of controls and stance was 134.9% wider than controls) and when making turns (velocity 50.6% of controls and stance 120.1% wider than that of controls). Accelerometry showed increased flexion/extension and lateral movement of the major joints in subjects with diabetes during both walking in a linear path and turns compared to control subjects. Part of the increased movement at the joints in the subjects with diabetes was due to tremor in both the 8 Hz and 16 Hz bands. These findings suggest that at least some of the increased joint movement during walking in people with diabetes is likely neurological in origin and not related to muscle weakness or loss of sensation in the feet.

Insulin and the insulin receptor in experimental models of learning and memory

Insulin is best known for its action on peripheral insulin target tissues such as the adipocyte, muscle and liver to regulate glucose homeostasis. In the central nervous system (CNS), insulin and the insulin receptor are found in specific brain regions where they show evidence of participation in a variety of region-specific functions through mechanisms that are different from its direct glucose regulation in the periphery. While the insulin/insulin receptor associated with the hypothalamus plays important roles in regulation of the body energy homeostasis, the hippocampus- and cerebral cortex-distributed insulin/insulin receptor has been shown to be involved in brain cognitive functions. Emerging evidence has suggested that insulin signaling plays a role in synaptic plasticity by modulating activities of excitatory and inhibitory receptors such as glutamate and GABA receptors, and by triggering signal transduction cascades leading to alteration of gene expression that is required for long-term memory consolidation. Furthermore, deterioration of insulin receptor signaling appears to be associated with aging-related brain degeneration such as the Alzheimer's dementia and cognitive impairment in aged subjects suffering type 2 diabetes mellitus.

Group II spindle fibres and afferent control of stance. Clues from diabetic neuropathy

OBJECTIVE

Since patients with large-fibre neuropathy do not show abnormal body sway during stance, the hypothesis was tested that postural control is not impaired until myelinated fibres of medium size are affected.

METHODS

In 22 diabetic neuropathic patients and 13 normals, we recorded: (1) body sway area (SA), (2) stretch responses of soleus (Sol) and flexor digitorum brevis (FDB) to toe-up rotation of a platform, (3) Sol and FDB H reflex and FDB F wave, (4) conduction velocity (CV) of tibial, deep peroneal and sural nerve. In patients, detection thresholds for vibration, cooling (CDT), warming and heat-pain (HPDT) were assessed.

RESULTS

Body SA was increased in patients with respect to normals. Toe-up rotation elicited short- (SLR) and medium-latency (MLR) responses in Sol and FDB in all normals. In patients, SLR was absent in FDB and reduced in Sol, and MLR was delayed in both muscles; the FDB H reflex was absent. The CV of tibial nerve group II afferent fibres, as estimated from the afferent time of FDB MLR, was reduced in patients. All sensory detection thresholds were increased. Stepwise multiple regression showed that increased SA was explained by increased latency of MLR, decreased CV of group II fibres and augmented CDT and HPDT.

CONCLUSIONS

Unsteadiness in diabetic neuropathy is related to alterations in medium-size myelinated afferent fibres, possibly originating from spindle secondary terminations.

Vestibulo-ocular, optokinetic and postural function in diabetes mellitus

We compared vestibulo-ocular reflex, optokinetic reflex and postural function in subjects with insulin-dependent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM), as well as non-diabetic controls. Both IDDM and NIDDM subjects exhibited significant deficits in gaze-holding in darkness (p < 0.05), small changes in vestibulo-ocular reflex (VOR) phase re velocity (p < 0.005) without a change in VOR gain, and a decrease in optokinetic reflex (OKR) slow phase velocity (p < 0.001). In addition, a smaller decrease was found in OKR quick phase amplitude (p < 0.02); postural sway was increased in both diabetic groups (p < 0.05), although this was not specific to the conditions of the Clinical Test of Sensory Interaction and Balance (CTSIB) that test vestibular contributions to postural stability. No differences were found in optokinetic afternystagmus or latency to circularvection. These results suggest that both IDDM and NIDDM are associated with deficits in gaze-holding, VOR and OKR function.

What can posturography tell us about vestibular function?

Patients with balance disorders want answers to the following basic questions: (1) What is causing my problem? and (2) What can be done about my problem? Information to fully answer these questions must include status of both sensory and motor components of the balance control systems. Computerized dynamic posturography (CDP) provides quantitative assessment of both sensory and motor components of postural control along with how the sensory inputs to the brain interact. This paper reviews the scientific basis and clinical applications of CDP. Specifically, studies describing the integration of vestibular inputs with other sensory systems for postural control are briefly summarized. Clinical applications, including assessment, rehabilitation, and management are presented. Effects of aging on postural control along with prevention and management strategies are discussed.

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

OBJECTIVES/HYPOTHESIS

To define and assess the functional impairment of the vestibular part of the inner ear in a diabetic state, using a direct and objective test for evaluating the vestibular end-organ and an animal model for diet-induced type 2 diabetes mellitus.

STUDY DESIGN

Prospective controlled animal study.

METHODS

Two groups of sand rats (Psammomys obesus) were maintained on two different diets. The experimental group received a specially designed high-energy diet known to induce a diabetic state, and the control group a low-energy diet maintaining these animals in a normal metabolic state. After 1 month of documented hyperglycemia in the experimental group, recordings of vestibular evoked potentials (VsEPs) and recordings of auditory brainstem response (ABR) were conducted in all animals. The latency and the amplitude of the first wave of both responses, shown to reflect end-organ activity, were compared between the two groups.

RESULTS

The mean latency of the first wave of the VsEPs was significantly (P = .002) prolonged and the amplitude was significantly (P = .005) decreased in the diabetic group in comparison to the control group. The latency of the first wave of ABR was significantly (P = .02) prolonged, the amplitude was not significantly decreased, and threshold was significantly elevated (P = .01) in the diabetic group.

CONCLUSION

For the first time, using an objective assessment test, functional impairment of the vestibular part of the inner ear has been demonstrated in the diabetic metabolic state. Despite this being an animal study, these findings would seem to indicate that the vestibular-end-organ should be added to the long list of organs and tissues adversely affected by diabetes.