Vibration sensation associated with motor function has specific frequency characteristics in community-dwelling older Japanese adults / 体力科学

Vibration sensation is related to motor function. However, it is unclear which vibration frequencies are associated with motor function. Therefore, in this cross-sectional study, we investigated whether a specific frequency of vibration sensation could explain motor functions. Thirty-two community-dwelling Japanese healthy older adults aged 70 years or older participated in the present study. Grip strength, one-leg standing time, and 10-m walking time were evaluated as indicators of motor function. Vibratory (40, 128, and 256 Hz) and tactile sensory tests were examined as sensory functions. Grip strength per body weight was significantly correlated with sex, body mass index, falls efficacy scale, vibration sensation with 40 and 128 Hz, and 10-m walking time (P < 0.05). Furthermore, one-leg standing time showed a correlation between vibration sensation (128 and 256 Hz) and fall history (P < 0.05). However, 10-m walking time was significantly correlated with only the grip strength to body weight ratio. Multiple regression analysis showed that vibration sensation with 128 Hz (β = 0.427) and sex (β = -0.335) (P < 0.05) were significant independent variables associated with grip strength to body weight ratio. Vibration sensation with 256 Hz (β = 0.465) and age (β = -0.343) (P < 0.05) were significant independent variable associated with one-leg standing time. No significant variables were identified for the 10-m walking time. Vibration sensation associated with motor function shows specific frequency characteristics in community-dwelling older Japanese adults.

Vibrotactile Perception for Sensorimotor Augmentation: Perceptual Discrimination of Vibrotactile Stimuli Induced by Low-Cost Eccentric Rotating Mass Motors at Different Body Locations in Young, Middle-Aged, and Older Adults.

Sensory augmentation technologies are being developed to convey useful supplemental sensory cues to people in comfortable, unobtrusive ways for the purpose of improving the ongoing control of volitional movement. Low-cost vibration motors are strong contenders for providing supplemental cues intended to enhance or augment closed-loop feedback control of limb movements in patients with proprioceptive deficits, but who still retain the ability to generate movement. However, it remains unclear what form such cues should take and where on the body they may be applied to enhance the perception-cognition-action cycle implicit in closed-loop feedback control. As a step toward addressing this knowledge gap, we used low-cost, wearable technology to examine the perceptual acuity of vibrotactile stimulus intensity discrimination at several candidate sites on the body in a sample of participants spanning a wide age range. We also sought to determine the extent to which the acuity of vibrotactile discrimination can improve over several days of discrimination training. Healthy adults performed a series of 2-alternative forced choice experiments that quantified capability to perceive small differences in the intensity of stimuli provided by low-cost eccentric rotating mass vibration motors fixed at various body locations. In one set of experiments, we found that the acuity of intensity discrimination was poorer in older participants than in middle-aged and younger participants, and that stimuli applied to the torso were systematically harder to discriminate than stimuli applied to the forearm, knee, or shoulders, which all had similar acuities. In another set of experiments, we found that older adults could improve intensity discrimination over the course of 3 days of practice on that task such that their final performance did not differ significantly from that of younger adults. These findings may be useful for future development of wearable technologies intended to improve the control of movements through the application of supplemental vibrotactile cues.

Low efficacy using the 256-Hz tuning fork when evaluating the influence of somatosensation in balance control for relatively healthy elderly.

BACKGROUND: Diminished foot somatosensation contributes to balance deficits and increased fall risk. However, it remains unclear if the 256-Hz tuning fork is adequate to measure, in the outpatient clinical setting, somatosensation in relatively healthy elderly. AIMS/OBJECTIVES: To evaluate the performance of the 256-Hz tuning fork compared to other measures of somatosensation and balance. MATERIAL AND METHODS: Thirty-six subjects (mean 69.4 ± 5.3 years) were allocated into four 256-Hz tuning fork sensation groups (TFSG) based on their ability to detect vibration at the first metatarsal, malleolus, tibia or no sites. A biothesiometer measured vibration perception thresholds (VPTs) and 20 monofilaments tactile pressure sensation thresholds (TPSTs). Balance was evaluated with posturography, functional balance tests and questionnaires. RESULTS: There were no significant differences in age, VPTs or TPSTs between the four TFSGs, nor in outcome of functional balance tests, posturography and questionnaires. Very few significant associations were found between TFSGs and VPTs, TPSTs, functional balance tests, posturography and questionnaires. CONCLUSIONS AND SIGNIFICANCE: Somatosensation measured with a 256-Hz tuning fork seems to be a minor determinant for balance and thus superfluous when evaluating the importance of vibration perception for balance control in relatively healthy elderly.

The effects of Vibro-medical insole on vibrotactile sensation in diabetic patients with mild-to-moderate peripheral neuropathy.

Peripheral sensory neuropathy seems to be the main risk factor for diabetic foot ulceration. Previous studies demonstrated that stochastic resonance can improve the vibrotactile sensation of diabetic patients. The aim of this study was to evaluate the effects of Vibro-medical insole on pressure and vibration sensation in diabetic patients with mild-to-moderate peripheral neuropathy. A total of 20 patients with mild-to-moderate diabetic neuropathy were included in the pre-test and post-test clinical trial study. Vibro-medical insole consists of medical insole and vibratory system. Medical insole was made independently for each participant and vibratory system was inserted in it. Pressure and vibration sensation were evaluated before and after 30-min walking with Vibro-medical insole. Semmes-Weinstein monofilaments and tuning fork were used to evaluate pressure and vibration sensation, respectively. Pressure sensation showed significantly improvement using Vibro-medical insole at the heel, first and fifth metatarsophalangeal heads, and hallux of both feet in all participants (p < 0.001). Vibration sensation also improved at the big toe of both feet with 256 Hz tuning fork (p < 0.05) but no statistically significant effect was found with 128 Hz tuning fork (p > 0.05). Vibro-medical insole significantly improved pressure and vibration sensation of the foot in diabetic patients with mild-to-moderate peripheral neuropathy. The results suggest that Vibro-medical insole can be used for daily living activities to overcome sensory loss in diabetic neuropathy patients.

Mobile phone generated vibrations used to detect diabetic peripheral neuropathy.

BACKGROUND: In the current United Kingdom population the incidence of diabetic peripheral neuropathy is increasing. The presence of diabetic neuropathy affects decision making and treatment options. This study seeks to evaluate if the vibrations generated from a mobile phone can be used to screen patients for diabetic peripheral neuropathy. METHODS: This study comprised of 61 patients; a control group of 21 patients; a lower limb injury group of 19 patients; a diabetic peripheral neuropathy group of 21 patients. The control and injury group were recruited randomly from fracture clinics. The diabetic peripheral neuropathy group were randomly recruited from the diabetic foot clinic. The 61 patients were examined using a 10g Semmes-Weinstein monofilament, a 128Hz tuning fork and a vibrating mobile phone. The points tested were, index finger, patella, lateral malleoli, medial malleoli, heel, first and fifth metatarsal heads. RESULTS: The most accurate location of all the clinical tests was the head of the 1st metatarsal at 0.86. The overall accuracy of the tuning fork was 0.77, the ten gram monofilament 0.79 and the mobile phone accuracy was 0.88. The control group felt 420 of 441 tests (95%). The injury group felt 349 of 399 tests (87%). The neuropathic group felt 216 of 441 tests (48%). There is a significant difference in the number of tests felt between the control and both the injury and neuropathic groups. p<0.0001 using N-1 Two Proportion Test. CONCLUSION: A mobile phone is an accurate screening tool for diabetic peripheral neuropathy. The most accurate location to test for diabetic peripheral neuropathy is the head of the 1st metatarsal. Screening for diabetic peripheral neuropathy in the index finger and patella were inaccurate. An injury to the lower limb affects the patient's vibration sensation, we would therefore recommend screening the contralateral limb to the injury. LEVEL OF EVIDENCE: This study represents level II evidence of a new diagnostic investigation.

Infantile onset spinocerebellar ataxia caused by compound heterozygosity for Twinkle mutations and modeling of Twinkle mutations causing recessive disease.

Mutations in nuclear genes required for the replication and maintenance of mitochondrial DNA cause progressive multisystemic neuromuscular disorders with overlapping phenotypes. Biallelic mutations in C10orf2, encoding the Twinkle mitochondrial DNA helicase, lead to infantile-onset cerebellar ataxia (IOSCA), as well as milder and more severe phenotypes. We present a 13-year-old girl with ataxia, severe hearing loss, optic atrophy, peripheral neuropathy, and hypergonadotropic hypogonadism. Whole-exome sequencing revealed that the patient is compound heterozygous for previously unreported variants in the C10orf2 gene: a paternally inherited frameshift variant (c.333delT; p.L112Sfs*3) and a maternally inherited missense variant (c.904C>T; p.R302W). The identification of novel C10orf2 mutations extends the spectrum of mutations in the Twinkle helicase causing recessive disease, in particular the intermediate IOSCA phenotype. Structural modeling suggests that the p.R302W mutation and many other recessively inherited Twinkle mutations impact the position or interactions of the linker region, which is critical for the oligomeric ring structure and activity of the helicase. This study emphasizes the utility of whole-exome sequencing for the genetic diagnosis of a complex multisystemic disorder.

Sensorimotor function and sensorimotor tracts after hemispherectomy.

Hemispherectomy is currently the only effective treatment for relieving constant seizures in children with severe or progressive unilateral cortical disease. Although early hemispherectomy has been advocated to avoid general dysfunction due to continued seizures, it remains unclear whether age at surgery affects specific sensorimotor functions. Little is know about the anatomical status of sensorimotor pathways after hemispherectomy and how it might relate to sensorimotor function. Here we measured motor function and sensory thresholds of the upper and lower limbs in 12 hemispherectomized patients. Diffusion tensor imaging (DTI) was used to determine status of brainstem corticospinal tracts and medial lemniscus. Hemispherectomy subjects showed remarkable recovery in both sensory and motor function. Many patients showed normal sensory vibration thresholds. Within the smaller Rasmussen's subgroup, we saw a relationship between age at surgery and sensorimotor function recovery (i.e. earlier was better). Anatomically, we found marked asymmetry in brainstem corticospinal tracts but preserved symmetry in the medial lemniscus, which may relate to robust sensory recovery. Age at surgery predicted anatomical status of brainstem sensorimotor tracts. In sum, we found that age at surgery influences anatomical changes in brainstem motor pathways, and may also relate to sensorimotor recovery patterns.

Quantitative Sensory Test in Normal Adult

OBJECTIVE: To obtain normal data of quantitative sensory test (QST) in Korean adult. METHOD: The subjects were 85 normal adults aging from 30 to 69 years old, who had no abnormal sensory and neurologic problem. We performed following three QSTs on dominant side and one verbal questionnaire. 1) Semmes-Weinstein monofilament wire system (0.05 G, 0.2 G, 2 G, 4 G, 10 G, 300 G) for touch sensation, 2) Rydel-Seiffer Tuning Fork for vibration sensation, 3) TSA-2001 Thermal sensory analyser for thermal sensation, 4)University of Texas Subjective Peripheral Neuropathy verbal questionnaire. RESULTS: 1) Touch perception score measured with Semmes-Weinstein monofilament wire system, declined with age (p<0.01). 2) Vibration perception score measured with the tuning fork, declined with age in foot (p<0.01). 3) Warm sense and heat pain threshold measured with TSA-2001 thermal sensory analyser increased with age, and cold sense and cold pain threshold declined with age. 4) Weight showed negative correlation with vibration perception score in man's foot. CONCLUSION: Normal data of three sensory test obtained from this study could be used for the early detection of peripheral neuropathy or loss of "protective sensation".

A Frequency Weighting Contour for Chinese Young Males / 航天医学与医学工程

Objective To obtain the frequency weighting contour for seated Chinese young males in z axis.Method 10 male volunteers served as the subjects.They were exposed to standard vibration stimulus (a sinusoidal vibration of 1.0 m/s2 at 8 Hz) and 14 kinds of sinusoidal experimental vibration stimuli at frequencies from 4 Hz to 80 Hz.The magnitude of the experimental vibration stimulus was changed by the subject through a signal condition and switching device made by ourselves to obtain an equal vibration sensation to the standard vibration.The data were fitted to the same form of the frequency weighting Wk of ISO 2631-1 with the least square method and optimization of parameters.Result Compared with ISO 2631-1,the frequencies weightings of Chinese young males at 16～80 Hz are significantly higher than those of ISO 2631-1(P<0.005),but there are no significant difference between two frequency weighting contours at other frequencies. Conclusion Chinese young males are more sensitive to vibration at 16～80 Hz in Z axis.

Quantitative Sensory Test for the Detection of Diabetic Peripheral Neuropathy / 대한정형외과학회잡지

The aim of this study was to compare widely used quantitative sensory tests to evaluate the diabetic neuropathy(DN). We tested plantar sensation of 40 patients with diabetes mellitus(Group I: 20 with neuropathic symtom, Group II: 20 without symptom) using Semmes-Weinstein monofilament(touch sensation), Biothesiometer(vibration sensation) and EMG. This result was also compared with that of the control group. Eighty percent of Group I and thirty percent of Group II had abnormal EMG findings. Group I had decreased vibration and touch sensation. Comparison of vibration perception threshold(Biothesiometer) with touch pressure sensation(Semmes-Weinstein monofilament) showed that the test with Biothesiometer was relatively accurate, however it was complicated, time consuming and that the test with monofilament was simple and easily performed in the field even though it was relatively crude. 5.07 monofilament could be very effective in the eearly detection of diabetic neumpathy. In conclusion, we recommend 5.07 monofilament as a screening method of diabetic neuropathy and biothesiometer as its follow-up method.