Determinants of vibration perception thresholds in IDDM and NIDDM patients

Vibration threshold in non-diabetic subjects

Measuring vibration perception threshold (VPT) accurately classifies and quantifies the severity of loss of vibration perception. A biothesiometer (Bio-thesiometer®; Bio Medical Instrument Co, Ohio, USA) appears to be the most suitable tool to determine VPT due to its low inter-rater variability and low occurence of adaption to the sensation. Different VPT values for a biothesiometer have been described, however, specification on age, height and different measurement locations is currently lacking. The objective of our study was to identify determinants of vibration perception in non-diabetic subjects, in order to provide individualized normal values of VPTs for clinical practice. Measurements of the vibration perception were performed on the big toes, insteps, lateral malleoli, and wrists. A total of 205 healthy subjects were included (108 (52.7%) males) with a median [interquartile range] age of 59 [51;64] (range 21-80) years. Mean height was 174.45 ± 9.20 cm and mean weight was 82.94 ± 14.84 kg, resulting in a mean BMI of 27.19 ± 4.00 kg/m2. In stepwise forward linear regression analyses, age (st. β = 0.51, p < 0.001) and height (st. β = 0.43, p < 0.001) were found to be the independent unmodifiable determinants of the VPT at the big toe. Regression coefficients for quantiles of the determinants age and height were incorporated in the corresponding regression equations. This study provides equations to calculate age- and height-specific normal values for VPT that can be used in clinical practice and in large research studies.

VSA-3000: A Quantitative Vibration Sensation Testing Device for Patients With Central Nervous System Injury

Objective: To investigate the effect of using Vibration Sensory Analyzer-3000 (VSA-3000) in patients with impaired vibration sensation caused by central nervous system injury.

Design: Prospective observational study.

Setting: A university hospital for the research and clinical practice of rehabilitation.

Subjects: Sixty patients (30 stroke and 30 spinal cord injury) were recruited, aged between 20 and 71 years old, under stable medication.

Interventions: Not applicable.

Main Measure: VSA-3000 threshold test, tuning fork test and somatosensory evoked potential (SSEP) measurement.

Results: Test-retest reliability was determined based on data collected from 60 subjects, and the intraclass correlation coefficient (ICC) for vibration perception thresholds (VPTs) was in the “substantial” range. The kappa value between VSA-3000 and SSEP was 0.877, which was higher than that of tuning fork (κ = 0.732). VSA-3000 had good diagnostic accuracy with a sensitivity of 94.8%, specificity of 92.9%, and positive-predictive value of 93.8% and negative-predictive value of 94.0%, each value was higher than that of tuning fork. The area under the receiver operating characteristic curve (AUC) of VSA-3000 was 0.95 (95% CI: 0.91 to 0.98) and that of tuning fork was 0.89 (95% CI: 0.85 to 0.95), and there was a significant difference between the two values (P = 0.0216). The types of injury and age were the independent correlates of the VPTs.

Conclusion: The present study provides preliminary evidence that VSA-3000 is a non-invasive and convenient quantitative testing instrument with good diagnostic accuracy, and it may be useful as a screening tool for assessing impaired vibration sensation caused by central nerve injury.

Usefulness of the vibration perception thresholds measurement as a diagnostic method for diabetic peripheral neuropathy: Results from the Rio de Janeiro type 2 diabetes cohort study

AIMS

To investigate the associated factors with the vibration threshold perception (VPT) in patients with type 2 diabetes and to assess whether it is useful for detection of diabetic peripheral neuropathy (DPN).

METHODS

VPTs were measured with Vibration Sensory Analyzer (VSA-3000) in 426 diabetic patients. The diagnosis of DPN was based on Neuropathy Symptom Score and Neuropathy Disability Score (NDS). ROC curve analysis and multiple linear and logistic regressions were performed to investigate the associations between VPT and DPN.

RESULTS

Values of VPT were progressively higher according to NDS stages. Age, height, diabetes duration, and mean cumulative HbA_1c exposure (partial correlation coefficients: 0.34; 0.27; 0.10; and 0.13; respectively) were the variables independently associated with VPT. Area under ROC curve of VPT for detection of DPN was 0.71 (95% CI: 0.66-0.75) and >8.9 μm was its best cut-off value. VPT, age, female sex, height, diabetes duration and mean HbA_1c levels were the independent correlates of the presence of DPN. An increased VPT triplicate the likelihood of having DPN (OR: 3.24; 95% CI: 2.05-5.11).

CONCLUSIONS

VPT, measured by an automatic device, shares common correlates with DPN and is strongly associated with its presence. VPT testing may be useful as a screening tool for DPN assessment.

Vibration perception threshold and the law of mobility in diabetic mellitus patients

BACKGROUND

Diabetic neuropathy is a family of nerve disorders with progressive loss of nerve function in 15% of diabetes mellitus (DM) subjects. Vibration Perception Threshold (VPT) is one of the modalities of testing loss of protective sensation. Law of mobility for VPT is well known for normal subjects, but not for diabetic subjects. This is a pilot study to evaluate and plot the law of mobility for VPT among DM subjects.

METHODS

We used biothesiometer to find the VPT of several areas in upper and lower extremities for normal and diabetic subjects. VPT of normal and diabetic subjects for different foot areas from proximal to distal is evaluated for 30 subjects. All the subjects are screened for peripheral artery occlusive disease with ankle brachial pressure index (0.9 or above). VPT values of different areas are arranged in a proximal to distal order for the analysis.

RESULTS

VPT values monotonically decrease from proximal to distal areas. Vierodt's law of mobility holds well for normal subjects in both feet areas. The law of mobility does not hold good for the DM subjects in one or both feet areas.

CONCLUSIONS

The VPT value of diabetic subjects reveals that the law of mobility do not holds good for diabetic subjects in foot areas. Though the number of subjects is small, all the subjects defied the law.

Quantitative vibration perception thresholds in normal and diabetic chinese: influence of age, height and body mass index

In this study, we established normality data of vibration perception thresholds (VPT) in a Chinese population. Over 1,400 healthy subjects were recruited to create age-related centile charts of VPT after pretesting for reliability. Another 273 diabetic (DM) patients were recruited to assess the impact of age, height and body mass index (BMI) on VPT values in DM and non-DM subjects. The present study is the first one which reports normality data of VPT from a large Chinese population. The VPT values were higher in male and female DM patients than in the non-DM counterparts. Age significantly contributed to the variance of VPT in both DM and non-DM subjects. Height was positively associated with VPT in men, so was BMI in non-DM subjects with much smaller magnitudes of effect than for age.

Limited joint mobility of the ankle in diabetic patients with cutaneous sensory deficit

Limited joint mobility (LJM) of the ankle joint was measured in 48 diabetic patients classified into three groups: Insulin-dependent diabetes mellitus (IDDM = 15), non-insulin diabetes mellitus (NIDDM = 12) and patients with cutaneous sensory deficit in the foot (CD = 21). Specifically, plantar flexion, dorsiflexion and total range of motion was measured on both feet using goniometric techniques during active and passive movement conditions. No significant bilateral differences were established, therefore values for the right foot were used for statistical analyses. Diabetic patients were matched to 48 non-diabetic controls for age, weight and gender factors. A Semmes-Weinstein monofilament test was used on both feet to assess the integrity of cutaneous sensitivity in all patient and control subjects. Cutaneous sensory deficit patients (CD) had monofilament values greater than two standard deviations below control group mean values. There were no significant differences between the monofilament test values for the IDDM and NIDDM patients and control group data. LJM results indicated both plantar flexion and range of motion in CD patients under active and passive movement conditions were significantly reduced compared to control group data. No differences were observed for any pairwise comparisons between the IDDM and NIDDM groups compared to controls. The data is discussed in terms of the interaction between LJM in the foot and type of diabetic classification.

Medical and pharmacologic management of upper extremity neuropathic pain syndromes

Written from a neurologic and therapeutically conservative perspective, this review advocates fundamentally medical and pharmacologic management of upper extremity neuropathic pain syndromes, including chronic regional pain syndromes, formerly classified reflex sympathetic dystrophy (RSD) and causalgia. Mandatory steps include, first, a prompt serious attempt to localize the nerve lesion whenever possible using complete, sophisticated neurologic examinations, then thoughtfully selected conventional neurophysiologic and radiologic tests. Strongly discouraged are promiscuous use of "RSD" to describe all neuropathic pains, and diagnostic reliance upon thermography and uncontrolled sympathetic blocks. Conservative multidisciplinary diagnostic and treatment teams should often possess a nucleus of neurologist and hand therapist, plus additional consultants including psychiatric. Every physician and therapist managing neuropathic pain must consider psychologic and wellness issues within their responsibilities. Prompt referral to an experienced surgeon is crucial for decompression or repair of relevant, significant, objectively proven (ideally neurophysiologically) nerve and root lesions. Ambiguous professional colloquialisms, "central pain" and "central sensitization," unfortunately provide value-laden pretexts for premature invasive treatments, and animate the truly dreadful concept "central RSD". Various classes of conventional oral non-narcotic adjuvant analgesics are reviewed, and the inevitability of their empiric, non-formulaic administration. No patient-specific, rationally-identifiable molecular receptor/switch can be deduced clinically or tripped mechanistically to terminate chronic pain. Two promising new non-narcotic centrally-active medications, gabapentin and tramadol, are highlighted as harbingers of future progress. The neglected subtle art of prescription writing is stressed, particularly for medication-sensitive patients. Medical cost containment should promote critical, long overdue outcomes studies comparing conservative and invasive pain treatments.