Serum biomarkers in patients with hand-arm vibration injury and in controls.

Hand-arm vibration injury is a well-known occupational disorder that affects many workers globally. The diagnosis is based mainly on quantitative psychophysical tests and medical history. Typical manifestations of hand-arm vibration injury entail episodes of finger blanching, Raynaud's phenomenon (RP) and sensorineural symptoms from affected nerve fibres and mechanoreceptors in the skin. Differences in serum levels of 17 different biomarkers between 92 patients with hand-arm vibration injury and 51 controls were analysed. Patients with hand-arm vibration injury entailing RP and sensorineural manifestations showed elevated levels of biomarkers associated with endothelial injury or dysfunction, inflammation, vaso- or neuroprotective compensatory, or apoptotic mechanisms: intercellular adhesion molecule-1 (ICAM-1), monocyte chemoattractant protein-1 (MCP-1); thrombomodulin (TM), heat shock protein 27 (HSP27); von Willebrand factor, calcitonin gene-related peptide (CGRP) and caspase-3. This study adds important knowledge on pathophysiological mechanisms that can contribute to the implementation of a more objective method for diagnosis of hand-arm vibration injury.

Fast grip force adaptation to friction relies on localized fingerpad strains.

During object manipulation, humans adjust the grip force to friction, such that slippery objects are squeezed more firmly than sticky ones. This essential mechanism to keep a stable grasp relies on feedback from tactile afferents innervating the fingertips, that are sensitive to local skin strains. To test if this feedback originates from the skin-object interface, we asked participants to perform a grip-lift task with an instrumented object able to monitor skin strains at the contact through transparent plates of different frictions. We observed that, following an unbeknown change in plate across trials, participants adapted their grip force to friction. After switching from high to low friction, we found a significant increase in strain inside the contact arising ~100 ms before the modulation of grip force, suggesting that differences in strain patterns before lift-off are used by the nervous system to quickly adjust the force to the frictional properties of manipulated objects.

Rare Median Nerve and Digital Nerve Tumor Resection and Distal Nerve Transfers: A Report of 2 Cases.

CASES: We present 2 cases of median nerve reconstruction using distal nerve transfers after resection of unusual benign median nerve tumors. Critical sensation was restored in case 1 by transferring the fourth common digital nerve to first web digital nerves. Thumb opposition was regained by transferring the abductor digiti minimi ulnar motor nerve branch to the recurrent median motor nerve branch. Critical sensation was restored in case 2 by transferring the long finger ulnar digital nerve to the index finger radial digital nerve. CONCLUSION: Distal nerve transfers, even with short grafts, are reliable median nerve deficit treatments, sparing the need for larger autologous nerve grafts and late tendon opponensplasties.

Altered brain function and structure in carpal tunnel syndrome: a systematic review and meta-analysis of structural and functional brain imaging.

This systematic review with a meta-analysis aimed to identify the altered brain structure and function in carpal tunnel syndrome (CTS) by summarizing the literature about magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI), and magnetoencephalography (MEG) outcomes compared to healthy controls (HC). CTS is the most common nerve entrapment in the arm associated with altered peripheral and central nociceptive system. PRISMA guidelines were used to report the outcomes. Six databases were searched for relevant literature (Web of Science, Scopus, PubMed, Sage, EBSCO host, and Cochrane). Eligible studies comparing MRI, fMRI, and MEG findings in people with CTS (present for at least 2 months) and HC through the following parameters: (1) interdigit cortical separation distance, (2) white and grey matter changes, (3) peak latency of M20 wave and recovery function of N20 from the somatosensory cortex (SI), and (4) surface area of activated digit cortical representation. The results from different studies were pooled and a meta-analysis was done. From 17 included, there was a significant reduction of interdigit cortical separation distance of index-middle and index-little fingers in the CTS (SMD = - 0.869, 95% CI (- 1.325, - 0.413), p-value = 0.000) and (SMD = - 0.79, 95% CI (- 1.217, - 0.364), p-value = 0.000), respectively. Middle-little fingers interdigit separation showed no difference (SMD = - 0.2, 95% CI (- 0.903, 1.309), p-value = 0.718). There is evidence supporting the altered brain structure and function in CTS as evidenced by reduction of interdigit cortical separation distance, and excessive blurring and disinhibition of SI, with low resting state functional connectivity. Thus, centrally directed therapeutic approaches might complement peripheral treatments.

Changes in the BOLD signal of S1 and BA3 per finger/phalanx as a response to high-frequency vibratory stimulation.

PURPOSE AND METHOD: The purpose of this study was to determine the changes in the Blood Oxygen Level Dependent signal of Primary somatosensory area (S1) and Brodmann area 3 (BA3) per finger and phalanx in comparison to the activation voxel when 250 Hz vibratory stimulation with high sensitivity for the Pacinian corpuscle was given to the four fingers and three phalanges. RESULTS: The result of analyzing the activation voxel showed a significant difference for S1 per finger and phalanx, but for BA3, no significant difference was observed despite a similar trend to S1. In contrast, the activation intensity (BOLD) displayed a significant difference for S1 per finger and phalanx and for BA3, where the activation voxel had no significant variation. In addition, while the result of S1 did not indicate whether the index or the little fingers had the highest sensitivity based on the BOLD signal per finger, the result of BA3 marked the strongest BOLD signal for the little finger as a response to 250 Hz vibratory stimulation. The activation intensity per phalanx was the highest for the intermediate phalanx for S1 and BA3, which was in line with a previous study comparing the activation voxel. CONCLUSIONS: The method based on the intensity of the nerve activation is presumed to have high sensitivity as the signal intensity is monitored within a specific, defined area. Thus, for the extraction of brain activation patterns of micro-domains, such as BA3, monitoring the BOLD signal that reflects the nerve activation intensity more sensitively is likely to be advantageous.

Index Finger Flexor Digitorum Profundus Function Deficit after Shoulder Arthroscopy Treated by Neurolysis: A Case Report.

A 60-year-old woman presented functional deficit of the index finger flexor digitorum profundus (FDP) tendon after shoulder arthroscopic rotator cuff repair. As no recovery was observed for 10 months, we conducted an operative exploration of the median nerve and the anterior interosseous nerve, followed by an external neurolysis. The patient recovered FDP function 4.5 months after the second operation. In a patient with persistent isolated FDP dysfunction after shoulder arthroscopy, operative exploration and external neurolysis could facilitate functional recovery. Level of Evidence: Level V (Therapeutic).

[Secondary surgical procedures following motor nerve injuries]. / Sekundäre operative Verfahren bei Verletzungen motorischer Nerven.

BACKGROUND: The functional deficits that develop after a peripheral nerve injury mean a considerable reduction in the quality of life for the affected patients. However, interventions on the injured nerve are not always possible or effective. In this case, secondary procedures, e.g. tendon transfers, are a feasible option for functional reconstruction. OBJECTIVES: An overview of the most common secondary surgical procedures for functional reconstruction after peripheral nerve injuries. METHODS: Presentation and discussion of the most common secondary surgical procedures with emphasis on tendon transfers. Illustration of the primary functions that need to be reconstructed depending on the respective nerve lesion. RESULTS: The basic principle of secondary surgical procedures after nerve injuries is the transposition of a healthy tendomuscular unit to replace a lost function following a loss of muscle or tendon or if an intervention on the nerve is not promising. For example, by transferring flexor forearm muscles, wrist, finger and thumb extension can be reconstructed after radial nerve injury. By transposing the tibialis posterior muscle, dorsiflexion in the talocrural joint can be restored to enable the affected patient to walk safely without an orthosis. CONCLUSIONS: Secondary surgical procedures are a valuable option for functional reconstruction after nerve injury.

[A V-Y shaped flap with digital artery nerve at metacarpophalangeal joint was used to repair the defect of middle and distal phalanx].

OBJECTIVE: To explore a surgical method for the reconstruction of volar soft tissue defect and sensory and vascular repair in middle and far phalangeal digits. METHODS: From January 2016 to January 2020, a total of 14 patients , 9 males and 5 females, ages ranging from 22 to 69 years old, and with volar soft tissue defects in the middle and distal digits 2 to 4, underwent surgical reconstruction using the V-Y shaped flap with digital artery and nerve at the metacarpophalangeal joint. The defect area was (2.0~2.5) cm×(1.5 ~2.0) cm. The procedure involved the harvest of a V-Y shaped flap with the digital artery and nerve from the metacarpophalangeal joint. Flap design, dissection of blood vessels and nerves, and anastomosis with the digital artery and nerve were performed according to a standardized protocol., Functional exercise of affected finger was initiated 3 weeks postoperatively. Subsequent assessments were conducted to evaluate finger pulp sensation, shape and other relevant parameters. According to the upper extremity functional evaluation standard set up by Hand Surgery Branch of Chinese Medical Association, the surgical outcomes were evaluated. RESULTS: All 14 cases demonstrated successful tissue transplantation, , with immediate recovery of sensation observed in 10 cases with distal finger pulp defects. Four patients with middle phalangeal defects experienced gradual sensory recovery within 2 to 3 months postoperatively. Thirteen patients were followed up for a mean duration of (8.8 ± 4.49) months, during which satisfactory outcomes were observed. The average two-point resolution of the finger pulp was 4-6mm, and sensory function evaluation yielded a score of S3 or above. Patients exhibited realistic finger shape, normal skin color and temperature, good wear resistance, and cold resistance. Furthermore, finger joint function was essentially normal. CONCLUSION: The V-Y shaped flap with digital artery and nerve at the metacarpophalangeal joint offers a suitable solution for repairing the defect of the middle or distal phalangeal finger. This technique is characterized by its simplicity, low risk, and favorable outcomes, including restored finger shape, blood supply and sensation. Moreover, high patient satisfaction was achieved.

Clinical Outcomes of Upper Extremity Nerve Transfers in Neuralgic Amyotrophy.

SUMMARY: Neuralgic amyotrophy (NA) is a disease affecting peripheral nerves. Treatment has historically been conservative, as the natural course of the disease was thought to be self-limiting. Recent work has demonstrated that as many as two-thirds of people with NA have persistent pain, fatigue, or weakness. At the authors' center, supercharged end-to-side (SETS) nerve transfers are commonly performed in patients with NA to optimize motor recovery while allowing for native axonal regrowth. The authors describe the technique and clinical outcomes of patients with NA affecting the anterior interosseous nerve (AIN) who were treated with SETS nerve transfer from extensor carpi radialis brevis to AIN. Ten patients (90% male; mean age, 51.3 ± 9.7 years) underwent extensor carpi radialis brevis-to-AIN transfer at a mean period of 6.4 ± 1.4 months after onset of symptoms. Mean postoperative follow-up duration was 14.8 ± 3.2 months. Before surgery, all patients demonstrated clinically significant weakness in the flexor pollicis longus (FPL), flexor digitorum profundus muscle to the index finger (FDP2), or both. FPL strength improved from a median Medical Research Council (MRC) grade of 1.5 to 4 ( P = 0.011) and FDP2 strength improved from a median MRC grade of 1 to 5 ( P = 0.016). A postoperative MRC grade of 4 or greater was achieved in nine of 10 (90%) FPL and 10 of 10 (100%) FDP muscles. This is the first report of SETS nerve transfer for the treatment of NA. The outcomes of this work suggest that SETS nerve transfers may be an option to optimize motor outcomes in patients with NA. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Digital Neuropathy by Hypertrophy and Hyperplasia of Pacinian Corpuscle - Usefulness of Microscopic Resection.

We present a patient with Pacinian corpuscle hypertrophy and hyperplasia in the hand and discuss the diagnosis and treatment of this rare condition. A 46-year-old woman presented with radiating pain of the left middle finger. A strong Tinel-like sign was elicited between the index and middle fingers. The patient frequently used mobile phone, with the corner of the phone consistently applying pressure on the palm. The surgery was carried out under the microscope and two enlarged cystic lesions under the epineurium were found in the proper digital nerve. Histologic examination revealed hypertrophied Pacinian corpuscle with normal structure. Postoperatively, her symptoms gradually improved. Preoperative diagnosis of this disease is very difficult. Hand surgeons should keep this disease in mind preoperatively. In our case, we would not have been able to identify multiple hypertrophic Pacinian corpuscles without the microscope. An operating microscope is recommended in a surgery of this nature. Level of Evidence: Level V (Therapeutic).

Outcomes and prognostic factors for nerve grafting following high radial nerve injury.

In this study, we examined the prognostic factors affecting outcomes following nerve grafting in high radial nerve injuries. Thirty-three patients with radial nerve injuries at a level distal to the first branch to the triceps and proximal to the posterior interosseous nerve were retrospectively studied. After a follow-up of at least 1 year, 24 patients (73%) obtained M3+ wrist extension, 16 (48%) obtained M3+ finger extension and only ten (30%) obtained M3+ thumb extension. Univariate, multivariate and receiver operating characteristic analyses showed that a delay in the repair of less than 6 months, a defect length of less than 5 cm or when grafted with three or more donor nerve cables achieved better recovery. Number of cables used was related to muscle strength recovery but not time to reinnervation. Nerve grafting for high radial nerve injury achieved relatively good wrist extension but poor thumb extension and is affected by certain prognostic factors. Level of evidence: IV.

Outcome After Reconstruction of 43 Digital Nerve Defects With Muscle-in-Vein Conduits.

PURPOSE: Muscle-in-vein conduits provide an alternative for bridging digital nerve defects when tension-free suture is not possible. Low donor site morbidity and absence of additional costs are favorable advantages compared with autografts or conduits. METHODS: We retrospectively reviewed 37 patients with 43 defects of proper palmar digital nerves. Primary repair by muscle-in-vein conduits was performed in 22 cases, whereas 21 cases underwent secondary reconstruction. Recovery of sensibility was assessed using static and moving 2-point discrimination and Semmes-Weinstein monofilament testing. Results were compared with the contralateral side serving as a control. Outcome data were stratified according to international guidelines and evaluated for differences in terms of age, gap length, time of reconstruction, and concomitant injuries. RESULTS: The median gap length was 20 mm (range, 9-60 mm). After a median follow-up of 25.0 months (interquartile range, 29.0 months), the median static and moving 2-point discrimination were 7.0 mm and 5.0 mm (interquartile range, 3.0 mm), respectively. The evaluation with Semmes-Weinstein monofilament revealed a median reduction of sensibility of 2 levels compared with the contralateral side. According to the American Society for Surgery of the Hand guidelines, 81.4% of the results were classified as excellent or good, whereas fair and poor results were noted in 9.3% of the cases each. The modified Highet and Sander's criteria rated complete clinical recovery in 13 cases; 23 results were regarded as S3+. CONCLUSIONS: Muscle-in-vein conduits can be considered for primary and secondary reconstruction of digital nerves. Successful sensory recovery in terms of measurable 2-point discrimination was achieved in 91% of all cases. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Distal Nerve Transfer to Restore Wrist and Finger Extension - A Systematic Review.

Background: There are numerous options available for restoration of wrist and finger extension following radial nerve palsy. The aim of this study is to conduct a systematic review of the effectiveness of nerve transfer for radial nerve palsy. Methods: Electronic literature research of PubMed, Cochrane, Scopus and Lilacs database was conducted in June 2021 using the terms 'Distal nerve transfer' AND 'Radial nerve injury' 'Radial nerve palsy' OR 'Radial nerve paresis' OR 'Median nerve transfer' OR 'wrist extensor' OR 'finger extension' OR 'thumb extension' OR 'wrist motion'. The data extracted included the study details, demographic data, procedure performed and final functional outcome according to the muscle research council scale. Results: A total of 92.59% and 56.52% had satisfactory outcome following distal nerve transfer of median nerve to restore wrist and finger extension respectively. No significant correlation was found between time to injury duration and satisfactory outcomes. Conclusions: Outcomes of nerve transfers are comparable to tendon transfers. Multi-centric studies are needed to compare the results amongst various surgical procedures described. Level of Evidence: Level III (Therapeutic).

The neural basis of tactile texture perception.

Running our fingers across a textured surface gives rise to two types of skin deformations, each transduced by different tactile nerve fibers. Coarse features produce large-scale skin deformations whose spatial configuration is reflected in the spatial pattern of activation of some tactile fibers. Scanning a finely textured surface elicits vibrations in the skin, which in turn evoked temporally patterned responses in other fibers. These two neural codes-spatial and temporal-drive a spectrum of neural response properties in somatosensory cortex: At one extreme, neurons are sensitive to spatial patterns and encode coarse features; at the other extreme, neurons are sensitive to vibrations and encode fine features. While the texture responses of nerve fibers are dependent on scanning speed, those of cortical neurons are less so, giving rise to a speed invariant texture percept. Neurons in high-level somatosensory cortices combine information about texture with information about task variables.

Posttraumatic Glomus Tumor of the Digital Nerve with Atypical Presentation: A Case Report.

CASE: A 53-year-old man sustained an injury to his left index finger and underwent presumably traumatic neuroma excision from the radial digital nerve 2 years ago. He presented with a painful mass distal to the prior site of neuroma excision with distinctly different symptoms from those that led to his index surgery. Thus, he underwent excisional biopsy of the mass which was adherent to his radial digital nerve consistent with a benign glomus tumor on histologic examination. CONCLUSION: Digital nerve glomus tumors are rare. In most of the cases, some portion of the digital nerve requires excision but decreased pain can be expected.

Single-stage double motor nerve transfer for all finger flexion in iatrogenic C8-T1 spinal nerve injury: a case report and review of literature.

Restoration of hand function after C8-T1 spinal nerve injury is challenging. We report a case of a young patient who underwent single-stage transfer of extensor carpi radialis brevis (ECRB) branch of radial nerve to flexor digitorum superficialis (FDS) branch of median nerve and transfer of brachialis branch of musculocutaneous nerve to anterior interosseous nerve (AIN), aiming for restoration of all finger flexion in iatrogenic C8-T1 spinal nerve injury after the resection of a dumbbell-shaped C8 neurofibroma. At 18 months after the operation, the fingers and thumb functions were successfully restored. The operation might be useful for restoration of hand function in selected patients with C8, T1 brachial plexus injury. From the literature review, this is the first case that the technique of double motor nerve transfer and the transfer of ECRB branch to FDS branch were used to restore finger flexion in a patient with brachial plexus injury.

The optimal duration for the wrinkle test in a clinical setting.

To determine the time needed or the development of a positive result on the wrinkle test among patients with complete laceration of a digital nerve in a clinical setting. We prospectively recruited 20 patients who had undergone surgery for digital nerve laceration. The wrinkle test was conducted at a follow-up session up to 2 months after surgery, and the time to a positive wrinkling result was recorded. The wrinkle test was compared between the patient's injured versus uninjured contralateral finger. The average time required for a positive result on the wrinkle test was 24.5 min (± 11), with 25% patients requiring 40 min to obtain a positive result. When evaluating a patient with digital nerve injury in a "non-laboratory" environment, the wrinkle test may require up to 40 min to obtain a positive result. Our study suggests that if tests are completed following the generally accepted time limit reported in the literature (30 min), up to 25% of tests may produce false negative results.

Combined Nerve and Tendon Transfers for C7-T1 Brachial Plexus Avulsion Injury.

BACKGROUND: In patients with C7-T1 brachial plexus avulsions, complete loss of hand function is commonly seen. However, the reconstruction of hand function is difficult. OBJECTIVE: To report the outcomes of hand function recovery after combined nerve and tendon transfers in C7-T1 brachial plexus injury. METHODS: From 2012 to 2019, 8 patients with C7-T1 brachial plexus injury underwent combined nerve and tendon transfers for hand function restoration, which included the following: (1) the pronator teres motor branch to the anterior interosseous nerve and brachialis motor branch to the flexor digitorum superficialis branch for finger flexion, (2) the supinator motor branch to the posterior interosseous nerve for finger extension, (3) the brachioradialis tendon transfer for thumb opposition, and (4) the radial branch of the superficial radial nerve to the sensory branch of the ulnar nerve for sensory reconstruction. Patients were evaluated for functional improvement of finger flexion, finger extension, thumb opposition, and sensory recovery. RESULTS: No clinical donor deficits were observed. Seven of eight patients recovered finger and thumb flexion (4 patients scored British Medical Research Council grade M4 and 3 scored M3). The average grip strength was 3.4 kg. All patients regained finger extension (4 scored M4 and 4 scored M3), thumb opposition, and protective sensation on the ulnar hand. Patients were able to use their reconstructed hands in daily lives. CONCLUSION: Combined nerve and tendon transfers are reliable and effective. This strategy could be an option for hand function reconstruction after C7-T1 brachial plexus injury.