Contralateral Hand Research Articles

The effects of concurrent bilateral anodal tDCS of primary motor cortex and cerebellum on corticospinal excitability: a randomized, double-blind sham-controlled study

Transcranial direct current stimulation (tDCS) applied to the primary motor cortex (M1), and cerebellum (CB) can change the level of M1 corticospinal excitability (CSE). A randomized double-blinded crossover, the sham-controlled study design was used to investigate the effects of concurrent bilateral anodal tDCS of M1 and CB (concurrent bilateral a-tDCSM1+CB) on the CSE. Twenty-one healthy participants were recruited in this study. Each participant received anodal-tDCS (a-tDCS) of 2 mA, 20 min in four pseudo-randomized, counterbalanced sessions, separated by at least 7 days (7.11 days ± 0.65). These sessions were bilateral M1 stimulation (bilateral a-tDCSM1), bilateral cerebellar stimulation (bilateral a-tDCSCB), concurrent bilateral a-tDCSM1+CB, and sham stimulation (bilateral a-tDCSSham). Transcranial magnetic stimulation (TMS) was delivered over the left M1, and motor evoked potentials (MEPs) of a contralateral hand muscle were recorded before and immediately after the intervention to measure CSE changes. Short-interval intracortical inhibition (SICI), intracortical facilitation (ICF), and long interval intracortical inhibition (LICI) were assessed with paired-pulse TMS protocols. Anodal-tDCS significantly increased CSE after concurrent bilateral a-tDCSM1+CB and bilateral a-tDCSCB. Interestingly, CSE was decreased after bilateral a-tDCSM1. Respective alterations in SICI, LICI, and ICF were seen, including increased SICI and decreased ICF, which indicate the involvement of glutamatergic and GABAergic systems in these effects. These results confirm that the concurrent bilateral a-tDCSM1+CB have a facilitatory effect on CSE, whereas bilateral a-tDCSM1 exert some inhibitory effects. Moreover, the effects of the 2 mA, 20 min a-tDCS on the CB were consistent with its effects on the M1.

E.L., a modern-day Phineas Gage: Revisiting frontal lobe injury

How the prefrontal cortex (PFC) recovers its functionality following lesions remains a conundrum. Recent work has uncovered the importance of transient low-frequency oscillatory activity (LFO; < 4 Hz) for the recovery of an injured brain. We aimed to determine whether persistent cortical oscillatory dynamics contribute to brain capability to support 'normal life' following injury. In this 9-year prospective longitudinal study (08/2012-2021), we collected data from the patient E.L., a modern-day Phineas Gage, who suffered from lesions, impacting 11% of his total brain mass, to his right PFC and supplementary motor area after his skull was transfixed by an iron rod. A systematic evaluation of clinical, electrophysiologic, brain imaging, neuropsychological and behavioural testing were used to clarify the clinical significance of relationship between LFO discharge and executive dysfunctions and compare E.L.´s disorders to that attributed to Gage (1848), a landmark in the history of neurology and neuroscience. Selective recruitment of the non-injured left hemisphere during execution of unimanual right-hand movements resulted in the emergence of robust LFO, an EEG-detected marker for disconnection of brain areas, in the damaged right hemisphere. In contrast, recruitment of the damaged right hemisphere during contralateral hand movement, resulted in the co-activation of the left hemisphere and decreased right hemisphere LFO to levels of controls enabling performance, suggesting a target for neuromodulation. Similarly, transcranial magnetic stimulation (TMS), used to create a temporary virtual-lesion over E.L.'s healthy hemisphere, disrupted the modulation of contralateral LFO, disturbing behaviour and impairing executive function tasks. In contrast to Gage, reasoning, planning, working memory, social, sexual and family behaviours eluded clinical inspection by decreasing LFO in the delta frequency range during motor and executive functioning. Our study suggests that modulation of LFO dynamics is an important mechanism by which PFC accommodates neurological injuries, supporting the reports of Gage´s recovery, and represents an attractive target for therapeutic interventions. Fundação de Amparo Pesquisa Rio de Janeiro (FAPERJ), Universidade Federal do Rio de Janeiro (intramural), and Fiocruz/Ministery of Health (INOVA Fiocruz).

Nonsurgical treatment of deep transverse metacarpal ligament injuries

The deep transverse metacarpal ligament (DTML) is a structure that extends between the head of the second to fifth metacarpal to maintain the stability of the transverse metacarpal arch. Injuries of this ligament due to blunt trauma produce DTML injury and present with pain, decreased grip strength, deflection and diastasis of the affected fingers. Several surgical techniques for its reconstruction have been described. However, we evaluated the evolution of two patients who presented this injury diagnosed in acute and treated conservatively. Immobilization with forearm plaster in the intrinsic plus position and syndactyly to the adjacent finger was performed for 4 weeks. At one year of follow-up, they presented no pain (VAS 0/10) and showed hand function with comparable mobility to the contralateral hand and no diastasis between the fingers. We consider that in the face of DTML lesions evaluated in the acute period, diagnosis through clinical and radiological evaluation, as well as nonsurgical treatment, are usually sufficient.

Features of Temperature Reactions of the Contralateral Hand during a Local Cold Test in Young Migrants from South Asia in the Conditions of the European North of Russia

Features of Temperature Reactions of the Contralateral Hand during a Local Cold Test in Young Migrants from South Asia in the Conditions of the European North of Russia

Office-Based Carpal Tunnel Release Using Ultrasound Guidance in a Community Setting: Long-Term Results.

Objectives: To report the safety and effectiveness of office-based carpal tunnel release (CTR) using ultrasound (US) guidance in a general community population.Methods: This was a prospective single-center study that evaluated patients treated with CTR using US guidance between March 2019 and August 2020 for whom one-year data were available. Procedures were performed in an office-based procedure room using local anesthesia. Main outcomes of this study included complications, Boston Carpal Tunnel Questionnaire scores (BCTQ-SSS, BCTQ-FSS) and Quick Disabilities of the Shoulder and Hand (QDASH) scores.Results: Among 88 patients (123 hands) aged 30 to 89 years with available one-year data, 29 patients had simultaneous bilateral procedures. No intraoperative complications were reported. Statistically significant and clinically important improvements in BCTQ-SSS, BCTQ-FSS and QDASH scores occurred within two weeks and persisted through one year of follow-up (p < 0.001). Outcomes were similar for simultaneous bilateral releases. During follow-up, one patient developed complex regional pain syndrome that was successfully treated and subsequently had CTR using US guidance on the contralateral hand. No other complications were observed during one-year follow-up.Conclusion: Office-based CTR using US guidance is safe, effective and provides sustained clinical improvements at one-year follow-up in a community population. Simultaneous bilateral procedures were well-tolerated and resulted in similar clinical improvements.

Midterm clinical outcomes of collateral ligament repair of the thumb and lesser digits: a retrospective analysis of 35 cases

BackgroundFinger collateral ligament injuries are common, and conservative treatment usually works well. However, complete ruptures that lead to instability could cause painful disability. This study presents our clinical experience and a qualitative functional evaluation following the surgical repair of the thumb and proximal interphalangeal (PIP) joint collateral ligament ruptures.MethodsThirty-five patients (22 men and 13 women), diagnosed via a physical examination and magnetic resonance imaging (MRI) with a total collateral ligament rupture in the metacarpophalangeal thumb (16) and PIP joints of the lesser digits (19) and treated surgically, were evaluated retrospectively. The limited range of motion; functional score by Saetta; disabilities of the arm, shoulder, and hand (DASH) score; pre- and post-operative pain, deformity level; and post-operative ability to grip keys, buttons, and jars were measured. The significance of the change between the pre and post-operative visual analog scale for pain (VAS) scores were evaluated using the Wilcoxon signed-rank test. The difference between the lesser digits and thumb groups by patient age was evaluated using the Mann–Whitney-U test. All data, such as the mean, range, and standard deviation, were calculated using SPSS.ResultsThe mean pre- and post-operative VAS scores were 4.8 (from 3 to 7) and 0.91 (0 to 4), respectively. The mean post-operative limitation in the range of motion was 9.78° (s = 14.47) for lesser digits and 6.87° (s = 12.29) for the thumb. According to Seatta et al., the final functional score was 62.5% excellent, 25% good, and 12.5% moderate for the thumb and 84.2% excellent, 10.5% good, and 5.3% poor for the lesser digits. The mean post-operative DASH score was 13.55 (SD: 8.77) for lesser digits and 14.22 (SD: 8.9) for the thumb. The mean contralateral (healthy) hand DASH score was 0.75 (SD: 1.05) for lesser digits and 0.75 (SD: 1.05) for the thumb. For the thumb and lesser digits, the z-scores were − 3.55 and − 3.787, respectively, and the progress of the VAS score was significant (p < 0.05).ConclusionAfter a 40-month follow-up for 35 acute, subacute, and chronic cases, the results suggest that direct and suture-anchor repairs are feasible, painless treatments associated with good finger function.

Catch the star! Spatial information activates the manual motor system

Previous research demonstrated a close bidirectional relationship between spatial attention and the manual motor system. However, it is unclear whether an explicit hand movement is necessary for this relationship to appear. A novel method with high temporal resolution-bimanual grip force registration-sheds light on this issue. Participants held two grip force sensors while being presented with lateralized stimuli (exogenous attentional shifts, Experiment 1), left- or right-pointing central arrows (endogenous attentional shifts, Experiment 2), or the words "left" or "right" (endogenous attentional shifts, Experiment 3). There was an early interaction between the presentation side or arrow direction and grip force: lateralized objects and central arrows led to a larger increase of the ipsilateral force and a smaller increase of the contralateral force. Surprisingly, words led to the opposite pattern: larger force increase in the contralateral hand and smaller force increase in the ipsilateral hand. The effect was stronger and appeared earlier for lateralized objects (60 ms after stimulus presentation) than for arrows (100 ms) or words (250 ms). Thus, processing visuospatial information automatically activates the manual motor system, but the timing and direction of this effect vary depending on the type of stimulus.

The impact of previous surgery on scaphoid nonunion reconstruction: a retrospective study of 95 cases.

We retrospectively compared 64 scaphoid reconstructions in cases that had not undergone previous surgery with 31 cases in which previous surgery had been performed. The characteristics of the groups were similar except that there were more smokers in the group without previous surgery and a more frequent use of vascularized bone grafts in the group with previous surgery. At final follow-up, 66 and 65months, respectively, after reconstruction, union incidence was 89% and 90%. In patients with previous surgery, grip strength was higher but not when expressed in percent of the contralateral hand. There were no differences in pinch strength, active wrist motion, functional scores, carpal height or scapholunate angle. We conclude that repeat surgery to the scaphoid did not seem to be a major risk factor for the overall outcomes, keeping in mind that a vascularized bone graft was more frequently used for secondary reconstructions.Level of evidence: III.

Mirror movements and brain pathology in children with unilateral cerebral palsy.

We systematically examined the relationship between mirror movements and brain lesion type, corticospinal tract (CST) organization, and hand function to determine the relevance between mirror movements, brain lesion, the CST pattern, and hand function in children with unilateral cerebral palsy (CP). Forty-eight children (mean age 9y 9mo[SD 3y 3mo], range 6-18y; 30 males, 18 females) with unilateral CP participated. Mirror movements, brain lesion type, CST pattern identified by transcranial magnetic stimulation, and clinical outcomes were evaluated. Children performed four unilateral tasks: hand opening/closing, finger opposition, individuation, and finger 'walking'. Mirror movements induced in the contralateral hand were scored using standardized criteria (scores 0-4 using the Woods and Teuber scale). We found that children with periventricular lesion may have stronger mirror movement scores induced in either hand than those with middle cerebral artery lesion (more affected hand: p=0.02; less affected hand: p<0.01). The highest mirror movement score a child exhibits across the tested tasks (i.e. scores of 3-4 using the Woods and Teuber scoring criteria) may potentially be an indicator of an ipsilateral CST connectivity pattern (p=0.03). Significant correlations were observed between higher mirror movement scores when performing hand opening/closing as well as finger walking and better unimanual dexterity (Spearman's rank correlation coefficient rs =0.44, p=0.002; rs =0.46, p=0.002 respectively). Brain lesions may be predictive of the strength of mirror movements in either hand in children with unilateral CP. Our findings warrant further studies to extensively investigate the relationship between mirror movements and the underlying brain pathology. Brain lesion type may be predictive of mirror movement scores induced in either hand in children with unilateral cerebral palsy. The highest mirror movement score a child exhibits across the tested tasks may indicate corticospinal tract connectivity pattern in children with unilateral cerebral palsy.

Cortical and Subthalamic Nucleus Spectral Changes During Limb Movements in Parkinson's Disease Patients with and Without Dystonia.

ABSTRACTBackgroundDystonia is an understudied motor feature of Parkinson's disease (PD). Although considerable efforts have focused on brain oscillations related to the cardinal symptoms of PD, whether dystonia is associated with specific electrophysiological features is unclear.ObjectiveThe objective of this study was to investigate subcortical and cortical field potentials at rest and during contralateral hand and foot movements in patients with PD with and without dystonia.MethodsWe examined the prevalence and distribution of dystonia in patients with PD undergoing deep brain stimulation surgery. During surgery, we recorded intracranial electrophysiology from the motor cortex and directional electrodes in the subthalamic nucleus (STN) both at rest and during self‐paced repetitive contralateral hand and foot movements. Wavelet transforms and mixed models characterized changes in spectral content in patients with and without dystonia.ResultsDystonia was highly prevalent at enrollment (61%) and occurred most commonly in the foot. Regardless of dystonia status, cortical recordings display beta (13–30 Hz) desynchronization during movements versus rest, while STN signals show increased power in low frequencies (6.0 ± 3.3 and 4.2 ± 2.9 Hz peak frequencies for hand and foot movements, respectively). Patients with PD with dystonia during deep brain stimulation surgery displayed greater M1 beta power at rest and STN low‐frequency power during movements versus those without dystonia.ConclusionsSpectral power in motor cortex and STN field potentials differs markedly during repetitive limb movements, with cortical beta desynchronization and subcortical low‐frequency synchronization, especially in patients with PD with dystonia. Greater knowledge on field potential dynamics in human motor circuits can inform dystonia pathophysiology in PD and guide novel approaches to therapy. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

The recent history of afferent stimulation modulates corticospinal excitability

BackgroundTranscranial magnetic stimulation (TMS) is widely used to probe corticospinal excitability and fast sensorimotor integration in the primary motor hand area (M1-HAND). A conditioning electrical stimulus, applied to the contralateral hand, can suppress the motor evoked potential (MEP) elicited by TMS of M1-HAND when the afferent stimulus arrives in M1-HAND at the time of TMS. The magnitude of this short-latency afferent inhibition (SAI) is expressed as the ratio between the conditioned and unconditioned MEP amplitude. Objective/HypothesisWe hypothesized that corticospinal excitability and SAI are influenced by the recent history of peripheral electrical stimulation. MethodsIn twenty healthy participants, we recorded MEPs from the right first dorsal interosseus muscle. MEPs were evoked by single-pulse TMS of the left M1-HAND alone (unconditioned TMS) or by TMS preceded by electrical stimulation of the right index finger (“homotopic” conditioning) or little finger (“heterotopic” conditioning). The three conditions were either pseudo-randomly intermixed or delivered in blocks in which a single condition was repeated five or ten times. MEP amplitudes and SAI magnitudes were compared using linear mixed-effect models and one-way ANOVAs. ResultsAll stimulation protocols consistently produced SAI, which was stronger after homotopic stimulation. Randomly intermingling the three stimulation conditions reduced the relative magnitude of homotopic and heterotopic SAI as opposed to blocked stimulation. The apparent attenuation of SAI was caused by a suppression of the unconditioned but not the conditioned MEP amplitude during the randomly intermixed pattern. Conclusion(s): The recent history of afferent stimulation modulates corticospinal excitability. This “history effect” impacts on the relative magnitude of SAI depending on how conditioned and unconditioned responses are intermixed and needs to be taken into consideration when probing afferent inhibition and corticospinal excitability.

Linking lesions in sensorimotor cortex to contralateral hand function in multiple sclerosis: a 7 T MRI study.

Cortical lesions constitute a key manifestation of multiple sclerosis and contribute to clinical disability and cognitive impairment. Yet it is unknown whether local cortical lesions and cortical lesion subtypes contribute to domain-specific impairments attributable to the function of the lesioned cortex.In this cross-sectional study, we assessed how cortical lesions in the primary sensorimotor hand area relate to corticomotor physiology and sensorimotor function of the contralateral hand. Fifty relapse-free patients with relapsing–remitting or secondary–progressive multiple sclerosis and 28 healthy age- and sex-matched participants underwent whole-brain 7 T MRI to map cortical lesions. Brain scans were also used to estimate normalized brain volume, pericentral cortical thickness, white matter lesion fraction of the corticospinal tract, infratentorial lesion volume and the cross-sectional area of the upper cervical spinal cord. We tested sensorimotor hand function and calculated a motor and sensory composite score for each hand. In 37 patients and 20 healthy controls, we measured maximal motor-evoked potential amplitude, resting motor threshold and corticomotor conduction time with transcranial magnetic stimulation and the N20 latency from somatosensory-evoked potentials.Patients showed at least one cortical lesion in the primary sensorimotor hand area in 47 of 100 hemispheres. The presence of a lesion was associated with worse contralateral sensory (P = 0.014) and motor (P = 0.009) composite scores. Transcranial magnetic stimulation of a lesion-positive primary sensorimotor hand area revealed a decreased maximal motor-evoked potential amplitude (P < 0.001) and delayed corticomotor conduction (P = 0.002) relative to a lesion-negative primary sensorimotor hand area. Stepwise mixed linear regressions showed that the presence of a primary sensorimotor hand area lesion, higher white-matter lesion fraction of the corticospinal tract, reduced spinal cord cross-sectional area and higher infratentorial lesion volume were associated with reduced contralateral motor hand function. Cortical lesions in the primary sensorimotor hand area, spinal cord cross-sectional area and normalized brain volume were also associated with smaller maximal motor-evoked potential amplitude and longer corticomotor conduction times. The effect of cortical lesions on sensory function was no longer significant when controlling for MRI-based covariates. Lastly, we found that intracortical and subpial lesions had the largest effect on reduced motor hand function, intracortical lesions on reduced motor-evoked potential amplitude and leucocortical lesions on delayed corticomotor conduction.Together, this comprehensive multilevel assessment of sensorimotor brain damage shows that the presence of a cortical lesion in the primary sensorimotor hand area is associated with impaired corticomotor function of the hand, after accounting for damage at the subcortical level. The results also provide preliminary evidence that cortical lesion types may affect the various facets of corticomotor function differentially.

Influence of Afferentation from the Contralateral Hand during Imitation of Cello Bowing in Musically Untrained Individuals

We studied hand movement during imitation of cello bowing while the rectilinear movement of the right bowing arm should occur in parallel with the bow orientation along the arm trajectory. Musically untrained individuals moved the bow across the bar that imitated the cello. Motion analysis was used to investigate the influence of a variety of experimental conditions: (1) bow motion on the bar surface, (2) on the left hand lying on the bar, and (3) in the air without touching the bar. It was found that the trajectory of the marker on the index finger at the bow frog differed significantly from the marker trajectory at the bow tip. In all conditions the marker on the index finger moved along a trajectory close to a straight line with an orientation slightly deviating from perpendicular to the bar. The marker trajectory at the bow tip deviated more from the perpendicular direction. Differences in the trajectories of markers at the bow frog and the bow tip depended on the condition of bow movement. The smallest differences were observed when the bow was moved on the left hand. It is suggested that sensation from the contralateral hand was used to create the internal representation of the relative position of the bow and the bar.

An Intraindividual Comparison of Open versus Paine Retinaculotome Release for Bilateral Carpal Tunnel Syndrome.

The main purpose of this research was to do an intraindividual comparison of outcomes between the open ulnar incision (OUI) and the Paine retinaculotome with palmar incision (PRWPI) techniques in patients with bilateral carpal tunnel syndrome (CTS). The patients underwent OUI surgery on one hand and PRWPI surgery on the contralateral hand. The patients were evaluated with the Boston carpal tunnel questionnaire, visual analogue scale for pain, palmar grip strength, and fingertip, key, and tripod pinch strengths. Both hands were examined in the preoperative and postoperative periods after 2 weeks, 1 month, and 3 and 6 months. Eighteen patients (36 hands) were evaluated. The symptoms severity scale (SSS) scores were higher, in the preoperative period, in the hands that underwent surgery with PRWPI ( p -value = 0,023), but lower in the 3rd month postoperative ( p -value = 0.030). The functional status scale (FSS) scores were lower in the periods of 2 weeks, 3 months, and 6 months ( p -value = 0,016) on the hands that underwent surgery with PRWPI. In a different two-group module study, the PRWPI group presents the SSS scores average on the 2nd week and 1st month, and the FSS scores average on the 2nd week, less 0.8 and 1.2 points respectively comported to open group. The hands that underwent surgery with PRWPI presented significantly lower SSS scores at 3 months postoperative, and lower FSS scores at 2 weeks, and 3 and 6 months postoperative, compared to open surgery group.

Visual uncertainty unveils the distinct role of haptic cues in multisensory grasping.

Human multisensory grasping movements (i.e., seeing and feeling a handheld object while grasping it with the contralateral hand) are superior to movements guided by each separate modality. This multisensory advantage might be driven by the integration of vision with either the haptic position only or with both position and size cues. To contrast these two hypotheses, we manipulated visual uncertainty (central vs peripheral vision) and the availability of haptic cues during multisensory grasping. We showed a multisensory benefit regardless of the degree of visual uncertainty suggesting that the integration process involved in multisensory grasping can be flexibly modulated by the contribution of each modality. Increasing visual uncertainty revealed the role of the distinct haptic cues. The haptic position cue was sufficient to promote multisensory benefits evidenced by faster actions with smaller grip apertures, whereas the haptic size was fundamental in fine-tuning the grip aperture scaling. These results support the hypothesis that, in multisensory grasping, vision is integrated with all haptic cues, with the haptic position cue playing the key part. Our findings highlight the important role of nonvisual sensory inputs in sensorimotor control and hint at the potential contributions of the haptic modality in developing and maintaining visuomotor functions.

The Efficacy of Remotely Supervised Transcranial Direct Current Stimulation on Conditioned Pain Modulation in Older Adults with Knee Osteoarthritis Pain

Osteoarthritis is a leading cause of pain, impaired daily function, and disability in older adults. Pharmacological and surgical interventions can increase the risk of side effects among older adults, and therefore, nonpharmacological interventions are promoted by the National Pain Strategy. Specifically, transcranial direct current stimulation (tDCS) targeting central nervous system pain processing has received growing attention for the treatment of chronic pain. Remotely supervised tDCS extended the analgesic properties of tDCS from the clinical setting to benefit participants in the comfort of their homes. Thus, we sought to assess the preliminary efficacy of tDCS on conditioned pain modulation in adults with knee OA pain. We conducted a single-group, open-label study in 20 community-dwelling older adults (ages 50–85 years) with knee osteoarthritis. tDCS with anode over the primary motor cortex and cathode with contralateral supraorbital region was applied with a constant current intensity of 2mA for 20 minutes every weekday for two weeks (Monday to Friday) for a total of 10 sessions. All tDCS sessions were remotely supervised by the trained research staff using secure videoconferencing software. Conditioned pain modulation (CPM) was measured by determining the change in pressure pain threshold on the trapezius immediately following immersion of the contralateral hand up to the wrist in a cold-water bath for up to one minute. The mean age of participants was 61 years (SD = 7 years), and 75% were female. CPM was significantly increased from 0.9 (SD=0.7) to 1.3 (SD=0.6) at the end of treatment (effect size = 0.4). Our preliminary results show that tDCS increased CPM in adults with knee OA. Randomized controlled trials with larger samples and longer-term follow-ups are needed to corroborate these promising findings regarding the effects of remotely supervised tDCS. This study was supported in part by the Theodore J. and Mary E. Trumble Endowment from The University of Texas Health Science Center at Houston and National Institute of Nursing Research (R15NR018050, R01NR019051).

Relationship between high-frequency activity in the cortical sensory and the motor hand areas, and their myelin content

BackgroundThe human primary sensory (S1) and primary motor (M1) hand areas feature high-frequency neuronal responses. Electrical nerve stimulation evokes high-frequency oscillations (HFO) at around 650 Hz in the contralateral S1. Likewise, transcranial magnetic stimulation (TMS) of M1 can evoke a series of descending volleys in the corticospinal pathway that can be detected non-invasively with a paired-pulse TMS protocol, called short interval intracortical facilitation (SICF). SICF features several peaks of facilitation of motor evoked potentials in contralateral hand muscles, which are separated by inter-peak intervals resembling HFO rhythmicity. HypothesisIn this study, we tested the hypothesis that the individual expressions of HFO and SICF are tightly related to each other and to the regional myelin content in the sensorimotor cortex. MethodsIn 24 healthy volunteers, we recorded HFO and SICF, and, in a subgroup of 20 participants, we mapped the cortical myelin content using the ratio between the T1- and T2-weighted MRI signal as read-out. ResultsThe individual frequencies and magnitudes of HFO and SICF curves were tightly correlated: the intervals between the first and second peak of cortical HFO and SICF showed a positive linear relationship (r = 0.703, p < 0.001), while their amplitudes were inversely related (r = −0.613, p = 0.001). The rhythmicity, but not the magnitude of the high-frequency responses, was related to the cortical myelin content: the higher the cortical myelin content, the shorter the inter-peak intervals of HFO and SICF. ConclusionThe results confirm a tight functional relationship between high-frequency responses in S1 (i.e., HFO) and M1 (i.e., as measured with SICF). They also establish a link between the degree of regional cortical myelination and the expression of high-frequency responses in the human sensorimotor cortex, giving further the opportunity to infer their generators.

Reconstruction of the distal radioulnar joint with rib perichondrium\xa0\u2013 midterm follow-up

BackgroundReconstruction of an osteoarthritic distal radioulnar joint (DRUJ) in patients with high physical demands and a long lifetime expectancy is challenging. A variety of methods like implant surgery and salvage procedures as partial or total ulnar head resection and the Sauve-Kapandji procedure are reasonable options in the elderly patient but not in young individuals since it often compromises manual power and stability and may cause impingement problems. Reconstruction of the DRUJ with rib perichondrium is a new treatment option with promising short-term outcome. The aim the present study was to investigate if the outcome is consistent over time.MethodsFour female patients with a mean age of 40.5 years suffered severe unilateral osteoarthritis in the DRUJ. They underwent reconstruction of the joint with rib perichondrium transplants. Preoperatively, mean pain under manual load was 8.5 (range 7–10) and 4.2 (range 2–5) at rest, using the visual analogue scale (VAS). Range of motion (ROM) in forearm rotation was on average 118° and grip strength was 86% in comparison to the contralateral hand. The outcome was assessed at a clinical follow-up in 2016, measuring ROM, grip-strength, pain at rest and under manual load and DASH-score. Radiological examination was performed. An additional follow-up by letter was performed in 2021 using a patient-reported-outcome survey (PROS). The patients were asked to grade the ROM and grip-strength as changed or unchanged in comparison to the clinical follow-up in 2016.ResultsAt clinical follow-up at a mean of 3.1 years (range 1–5) after surgery, pain level had decreased to VAS 1.5 (0–5) under load and all patients were pain free at rest. Forearm rotation was on average 156° (range 100–180) and grip strength was 97% of the unoperated hand. The mean DASH-score was 14.4 (0–45). An additional follow-up by letter was conducted at a mean of 7.5 years (5.5–9.5) after surgery. ROM and grip strength were reported as unchanged by all patients in relation to the previous clinical follow-up. No additional surgery or complications were reported.ConclusionReconstruction of the osteoarthritic DRU-joint with rib perichondrium transplantation can provide good clinical outcome with perseverance over time.Level of evidenceIV.

Modulation of subjective peripheral sensation, F-waves, and somatosensory evoked potentials in response to unilateral pinch task measured on the contractile and non-contractile sides.

Depression of the sensory input during voluntary muscle contractions has been demonstrated using electrophysiological methods in both animals and humans. However, the association between electrophysiological responses of the sensory system and subjective peripheral sensation (SPS) during a voluntary muscle contraction remains unclear. This study aimed to describe the changes in SPS, spinal α-motoneuron excitability (F-wave to M-wave amplitude), and somatosensory evoked potentials (SEPs) during a unilateral pinch-grip task. Outcome variables were measured on the side ipsilateral and contralateral to the muscle contraction and at rest (control). Participants were 8 healthy men aged 20.9±0.8 years. The isometric pinch-grip task was performed at 30% of the maximum voluntary isometric force measured for the right and left hands separately. The appearance rate of the F-wave during the task was significantly higher for the ipsilateral (right) hand than for the contralateral (left) hand and control condition. Although there was no difference in the F-wave latency between hands and the control condition, the amplitude of the F-wave was significantly higher for the ipsilateral (right) hand than for the contralateral (left) hand and the control condition. There was no difference in the amplitude of the SEP at N20. However, the amplitude at P25 was significantly lower for the ipsilateral (right) hand than for the contralateral (left) hand and the control condition. The accuracy rate of detecting tactile stimulation, evaluated for 20 repetitions using a Semmes–Weinstein monofilament at the sensory threshold for each participant, was significantly lower during the pinch-grip task for both the ipsilateral (right) and contralateral (left) hands than in the control condition. Overall, our findings show that SPS and neurophysiological parameters were not modulated in parallel during the task, with changes in the subjective sensation preceding changes in electrophysiological indices during the motor task. Our findings provide basic information on sensory-motor coordination.

Performance and Acceptability of a New Dexpanthenol-Containing Hand Cream in Subjects with Sensitive and Very Dry Skin: A Randomized Controlled Study

A new dexpanthenol-containing hand cream (ND-HC) was developed for people with dry, sensitive, and/or environmentally stressed hands. To explore the performance and acceptability of ND-HC, we conducted a randomized, intraindividual comparison study in 40 healthy adult subjects with sensitive and very dry skin on the hands. Instrumental measurements determined the effects on stratum corneum (SC) hydration and transepidermal water loss (TEWL) after single and/or 4 weeks’ use of ND-HC. Single and continued at least four times daily applications of ND-HC to very dry skin of the hand for 4 weeks triggered significant increases in SC hydration. On day 29, the mean change in skin capacitance from baseline was significantly greater when ND-HC was applied to the test area compared with the untreated area on the contralateral hand (12.41 vs. 4.46 a.u.; p &lt; 0.001). Upon use of ND-HC over 4 weeks, mean TEWL decreased significantly (bilateral difference: −1.8 vs. 1.0 g/m2/h; p = 0.003), indicating an improvement in SC barrier function. A reduction in dry hand symptoms was observed over the study course. ND-HC was well tolerated and achieved a high level of acceptance and satisfaction. Our findings suggest that ND-HC complies with the required features of a state-of-the-art hand cream.