A Prototype of an Electronic Pegboard Test to Measure Hand-Time Dexterity with Impaired Hand Functionality

This paper proposes an electronic prototype of the Grooved Pegboard Test (GPT), which is normally used to test the presence of hand dexterity. The prototype imitates the geometrical dimensions of an on-the-market GPT device, but it is electronic, not manual like the one available now for users. The suggested electronic GPT device makes automated time calculation between placing the first and the last peg in their designated locations, instead of manually observing a stopwatch normally used during the GPT. The electronic GPT prototype consists of a fabricated wooden box, electronics (switches and microcontroller), and liquid crystal display (LCD). A set of 40 normal volunteers, 20 females and 20 males, tested the designed prototype. A set of six volunteers with chronic medical conditions also participated in evaluating the proposed model. The results on normal volunteers showed that the proposed electronic GPT device yielded time calculations that match the population mean value of similar calculations by the GPT device. The one-sample t-test showed no significant difference in calculations between the new electronic GPT and the manual GPT device. The p-value was much higher than 0.05, indicating the possible use of the suggested electronic GPT device.

Finger stability in precision grips

Stable precision grips using the fingertips are a cornerstone of human hand dexterity. Occasionally, however, our fingers become unstable and snap into a hyper-extended posture. This is because multi-link mechanisms, like our fingers, can buckle under tip forces. Suppressing this instability is crucial for hand dexterity, but how the neuromuscular system does so is unknown. Here we show that finger stability is due to the stiffness from muscle contraction and likely not feedback control. We recorded maximal force application with the index finger and found that most buckling events lasted less than 50ms, too fast for sensorimotor feedback to act. However, a biomechanical model of the finger predicted that muscle-induced stiffness is also insufficient for stability at maximal force unless we add springs to stiffen the joints. We tested this prediction in 39 volunteers. Upon adding stiffness, maximal force increased by 34±3%, and muscle electromyography readings were 21±3% higher for the finger flexors (mean±standard error). Hence, people refrain from applying truly maximal force unless an external stabilizing stiffness allows their muscles to apply higher force without losing stability. Muscle recordings and mathematical modeling show that the splint offloads the demand for muscle co-contraction and this reduced co-contraction with the splint underlies the increase in force. But more stiffness is not always better. Stiff fingers would interfere the ability to passively adapt to complex object geometries and precisely regulate force. Thus, our results show how hand function arises from neurally tuned muscle stiffness that balances finger stability with compliance.

Bimanual digit training improves right-hand dexterity in older adults by reactivating declined ipsilateral motor-cortical inhibition

Improving deteriorated sensorimotor functions in older individuals is a social necessity in a super-aging society. Previous studies suggested that the declined interhemispheric sensorimotor inhibition observed in older adults is associated with their deteriorated hand/finger dexterity. Here, we examined whether bimanual digit exercises, which can train the interhemispheric inhibitory system, improve deteriorated hand/finger dexterity in older adults. Forty-eight healthy, right-handed, older adults (65–78 years old) were divided into two groups, i.e., the bimanual (BM) digit training and right-hand (RH) training groups, and intensive daily training was performed for 2 months. Before and after the training, we evaluated individual right hand/finger dexterity using a peg task, and the individual state of interhemispheric sensorimotor inhibition by analyzing ipsilateral sensorimotor deactivation via functional magnetic resonance imaging when participants experienced a kinesthetic illusory movement of the right-hand without performing any motor tasks. Before training, the degree of reduction/loss of ipsilateral motor-cortical deactivation was associated with dexterity deterioration. After training, the dexterity improved only in the BM group, and the dexterity improvement was correlated with reduction in ipsilateral motor-cortical activity. The capability of the brain to inhibit ipsilateral motor-cortical activity during a simple right-hand sensory-motor task is tightly related to right-hand dexterity in older adults.

Diverse Motor Performances Are Related to Incident Cognitive Impairment in Community-Dwelling Older Adults

Objective: Late-life cognitive impairment is heterogeneous. This study examined to what extent varied motor performances are differentially associated with incident Alzheimer’s dementia (AD) and incident mild cognitive impairment (MCI) in older adults.Design: Nested substudy.Setting: Communities across metropolitan Chicago.Participants: African American (N = 580) and European American (N = 580) adults without dementia, propensity-balanced by age (mean = 73.2; SD = 6.0), sex (78.4% women), education (mean = 15.6; SD = 3.3) and number of follow ups.Measurements: Cognitive status was assessed annually and based in part on a composite measure of global cognition including 17 cognitive tests. A global motor score was based on 10 motor performances from which 4 motor domains were computed including hand dexterity, hand strength, gait function, and leg strength.Results: During 7 years of follow-up, 166 of 1,160 (14.3%) developed AD. In a proportional hazards model controlling for age, sex, education, and race, each 1-SD higher baseline global motor score was associated with about a 20% reduction in the risk of AD (hazard ratio: 0.81; 95% CI: 0.68, 0.97). Higher baseline motor function was also associated with decreased risk of incident MCI (hazard ratio: 0.79; 95% CI: 0.68, 0.92). Hand dexterity, hand strength and gait function but not leg strength were associated with incident AD and MCI. When including all four motor domains in the same model, results remained the same for incident MCI, while for incident AD, the association with hand strength remained significant.Conclusion: Diverse motor performances are associated with late-life cognitive impairment. Further work is needed to identify specific motor performances that may differentiate adults at risk for future MCI or AD dementia.

Hand dexterity rehabilitation using selective functional electrical stimulation in a person with stroke

We report a 69 year old who suffered a cardioembolic ischaemic stroke on 23 September 2019, which resulted in a left hemiplegia with motor impairment in upper and lower extremities that made impossible for her to use the affected arm in daily living activities. The person commenced her comprehensive physiotherapy programme based on functional electrical stimulation (FES) in Fesia Clinic rehabilitation centre in October 2020. A multifield technology-based FES device was used, which allowed to train different selective movements in isolation and combined with mirror therapy, achieving excellent functional outcomes.

Influence of Low BMI on Handgrip Strength, Handgrip Endurance and Hand Dexterity in School Going Children- A Pilot Study

Introduction: The hand is the most dynamic and interactive part of the upper limb in humans and performing the complex tasks of daily living activities. The health problems due to less-than-optimal nutritional status in primary school-age children are among the most common causes of low school enrolment, high absenteeism, early dropout, and unsatisfactory classroom performance. Purpose: To compare handgrip strength, handgrip endurance, and hand dexterity in 6–12 years children with low and normal body mass index. Methodology: This pilot study was conducted among children with normal development. The age group included in the study was 6-12 years. The estimated sample 25 in each group. Participants underwent initial assessment, where height and weight were measured. To measure handgrip strength and handgrip endurance baseline hydraulic hand dynamometer and hand dexterity were assessed using a 9-hole pegboard, the participants were asked to perform three successful trials, and the mean of it was obtained. Results: Result shows that there was a significant difference between handgrip strength with BMI, with p< 0.01and no significant difference between handgrip endurance and hand dexterity with p>0.05 in children. Conclusion: The results of the current study demonstrated that 6-12-year-old children had a significant difference in handgrip strength of the dominant and non-dominant hand between low BMI and normal BMI children. With further research, it is important to find and compare the differences in a larger population. Keywords: Body mass index, dominant hand, handgrip strength, handgrip endurance, hand dexterity, non-dominant hand.

Diabetic Peripheral Neuropathy Affects Pinch Strength and Hand Dexterity in Elderly Patients

Objective. Diabetic peripheral neuropathy (DPN) is one of the most common chronic complications of diabetes, leading to disability and decreased quality of life. In past research and clinical studies, the lower limb function of DPN patients was often the principal subject of research, with little attention given to the upper limb and hand. Our goal was to assess and compare hand function between elderly diabetic patients with DPN and without DPN. Methods. A total of 52 diabetic patients were registered and underwent hand function assessments and electrodiagnostic tests. Dynamometer, pinch meter, Semmes Weinstein monofilaments, and the Purdue Pegboard Test (PPT) were used to assess the patients’ grip strength, pinch strength, tactile sensory threshold, and hand dexterity. Results. Compared with the non-DPN group, the elderly DPN group showed worse thumb-middle fingertip pinch strength and thumb-little fingertip pinch strength in the dominant hand (3.50 (2.50, 4.25) vs. 4.50 (3.00, 5.00), p = 0.019 ; 1.50 (1.00, 2.00) vs. 2.50 (2.00, 3.00), p < 0.001 ); the elderly DPN group displayed worse thumb-middle fingertip pinch strength, thumb-ring fingertip pinch strength, and thumb-little fingertip pinch strength in the nondominant hand (3.50 (2.00, 4.50) vs. 4.00 (3.00, 5.00), p = 0.013 ; 2.50 (1.25, 3.00) vs. 3.00 (2.50, 3.50), p = 0.033 ; 1.00 (0.75, 2.25) vs. 2.50 (2.00, 2.50), p < 0.001 ). The elderly DPN group scored lower than the non-DPN group on the PPT test of assembly ( 13.96 ± 5.18 vs. 16.96 ± 4.61 , t = 2.212 , p = 0.032 ). Conclusion. Motor function limitation is the principal hand dysfunction in elderly patients with DPN, which is mainly manifested as a decline in fingertip pinch strength and a decrease in hand dexterity. This trial is registered with Clinical Trial Registry no. ChiCTR1900025358.