In Vivo Reflectance Microscopy of Meissner Corpuscles and Bedside Measures of Large Fiber Sensory Function: A Normative Data Cohort

Background and Objectives:To establish age-, gender- and body dimension-adjusted normal cut-off values for Meissner’s corpuscle (MC) densities via in-vivo reflectance confocal microscopy (RCM), timed vibration sensory thresholds using a 128Hz tuning fork, and touch-pressure sensory thresholds using standardized monofilaments, for clinical and research application.Methods:77 prospectively recruited individuals without signs or symptoms of peripheral neuropathy or a condition or neurotoxin exposure that can alter sensory function underwent cross-sectional evaluation of MC densities via in-vivo RCM, monofilament touch-pressure sensory thresholds, and timed vibration sensory thresholds in non-dominant upper and lower extremities. Age-, gender-, and body dimension- (e.g., height) adjusted normal values were developed. The 5th percentile for MC densities and timed vibration thresholds and 95th percentile for MF touch-pressure thresholds were selected as normal cut-off points.Results:Subjects were aged 9 to 89 years old. Age and gender were uniformly distributed. Timed vibration and touch-pressure thresholds were less sensitive with increasing age and were more sensitive in the hand than in the leg or foot within individuals. Timed vibration thresholds did not differ by gender or body dimensions. Touch-pressure thresholds were lower (more sensitive) at the thenar eminence and digit V in the hand in women compared to men but otherwise did not differ by gender at other measurement locations. Body dimensions did not affect touch-pressure thresholds. There were no apparent age-related floor effects for the 5th and 95th percentile normal cutoff values for timed vibration or touch-pressure thresholds, respectively. MC densities also declined with age and were highest at digit V and lowest at the arch within individuals. MC densities were affected by gender or body dimensions at all imaging sites, with lower densities seen in males or larger individuals. MC densities were quantifiable in the hand of all participants and were associated with touch-pressure thresholds at all locations.Discussion:This study establishes age-, gender- and body dimension-adjusted normal cut-off values for two easily applied measures of large fiber sensory function and RCM assessment of MC densities for multiple limb locations. These results will aid in the detection and monitoring of peripheral sensory nerve disorders.

Usefulness of Scissors with a Power-Support Mechanism to Assist Thumb Movement: An Observational Study

Long-term repetitive movements, such as opening and closing scissors, increase strain on muscles and joints. Amplitude probability distribution function (APDF) analysis of surface electromyogram (sEMG) data was used to quantify the burden of muscle activity. We aimed to test the hypothesis that scissors with a power-support device assist repetitive thumb movements to reduce potential myoelectric activity. Twenty female university students who met the eligibility criteria performed a cutting experiment, with and without power-support device scissors. The primary outcome was a change in muscle load due to sEMG data that were analyzed using APDF, and the secondary outcomes investigated the occurrence of muscle fatigue and pain. The adductor pollicis muscle showed a significant decrease in muscle activity with power assistance. In addition, it was also found that fatigue and pain of the thumb and on the radial side of the forearm were significantly lower under the power-assisted conditions. The results of this study suggest that the assistive action of scissors with a power-support device compensate for muscle load on the thenar eminence. This may be used as a reference value to prevent the occurrence of hand disorders for hairdressers.

PREVALENCE OF MUSCULOSKELETAL DISORDER IN SMARTPHONE USERS: CROSS SECTIONAL STUDY

The smartphone supersedes the capability of the cellular phone, as it offers the user internet access, in addition to various applications for social, finical, entertainment, and healthcare needs. So, the aim of the study prevalence of the musculoskeletal disorder in people using smartphones ranging from the age group of 18 to 30 years. Objective: To find out musculoskeletal disorders occurring due to smartphone use. A total of 500 participates were screened according to the inclusion criteria all the participants were assessed for pain using the visual analogue scale in who use a smartphone. In the age group 18-30 years, 3 groups were made. The first group was between 18-21 years, the second group was 22-25 years, and the third group 26-30 years respectively. 18-21 years age group had 169 affected respondents. Area A represents the index, middle and lateral half of the ring finger. Area B represents the medial half of the ringer finger and little finger, Area C represents Thumb, Area D represents the central palmar aspect, Area E represents the Thenar eminence and Area F represents the Hypothenar region of the hand. The present study shows that the overall prevalence of the musculoskeletal disorder in smartphone users is 68%. Males are more affected than females. In this study neck and thumb were more affected regions compared to other parts of the body, secondary to the neck and thumb, the wrist is the affected region. Long-time use of smartphones leads to the repeated strain injury of the wrist and thumb, long time flexion of the neck during smartphone use leads to neck pain.

Transcranial direct-current stimulation (tDCS) in the primary motor cortex and its effects on sensorimotor function: a quasi-experimental single-blind sham-controlled trial

The main aim was to assess the short-term effects of active-tDCS (a-tDCS) in the primary motor cortex (anodal stimulation-M1) on sensorimotor variables. These variables included discriminative sensation through the two-point discrimination (2-PD) test, tactile acuity threshold and pressure pain threshold (PPT), and electromyographic (EMG) activity compared with a sham-tDCS (s-tDCS) in healthy individuals. A total of 100 participants were included. Fifty of the participants received the a-tDCS application of 2 mA for 20 min, whereas the remaining fifty received the s-tDCS. The 2-PD and tactile acuity threshold in thenar eminence of the hand and in the dorsal part of the foot and also, PPT and EMG activity during maximal voluntary contraction in the biceps brachii and rectus femoris were assessed before and after the tDCS application. The a-tDCS intervention was not significantly superior to the s-tDCS in any variable. However, significant within-group pre- and post-intervention differences were found in the a-tDCS, such as the tactile acuity threshold in thenar eminence of the hand, with a small effect size (p = .012, d = 0.20) and in the PPT of the rectus femoris, also with a small effect size (p = .001, d = − 0.17). Regarding EMG activity, a trend towards greater activity was observed in participants with a-tDCS compared with s-tDCS, which showed a trend towards decreased EMG activity. In fact, although no differences were found between the groups, within-group differences were statistically significant in the biceps brachii pre- and postintervention (p = .023, d = − 0.16, and p = .002, d = 0.18, respectively), and also in the rectus femoris, only in the a-tDCS, with a small effect size (p = .011, d = − 0.14). This study showed no significant between-group differences in sensorimotor outcomes. A single session of tDCS in isolation appears to produce immediate effects in healthy participants on sensorimotor function; however, these effects were very small.

Intraneural Synovial Sarcoma of the Median Nerve in a 15-Year-Old Male: A Case Report and Review of Literature

There have been 8 synovial sarcomas of the median nerve reported. We report a case of a 15-year-old male with synovial sarcoma of the right-hand median nerve. Patient presented with a 2-month history of enlarging mass at the base of the right thenar eminence associated with numbness in the median nerve distribution. Physical examination revealed a soft mass over the thenar eminence and paresthesia in the median nerve distribution. He underwent excision of the tumor, which revealed a well-encapsulated lesion encompassing the median nerve, involving the first, second, and radial aspect of the third web space as well as recurrent branches of the median nerve. Following excision of the tumor, a thorough metastatic workup was negative for metastatic disease. He was staged as III, T2b, N0, M0—poorly differentiated monophasic synovial sarcoma of the right median nerve. Postoperatively the patient was started on chemotherapy and radiation. Intraneural synovial sarcoma is extremely rare. Our case is the youngest with the longest follow-up. He is currently at a status of 3 years posttreatment with no signs of recurrence and excellent use of his right hand. This case is of particular interest due to the rarity of the disease along with this being the best outcome reported in the literature to-date.