Intermediate conduction velocity in two cases of Charcot-Marie-Tooth disease type 1A

BACKGROUND AND PURPOSE

Charcot-Marie-Tooth disease type 1A (CMT1A) is the most prevalent hereditary neuropathy worldwide and classically has slow nerve conduction velocity (NCV), in most cases below 38 m/s. Two unrelated patients with motor NCVs in the upper limbs above 38 m/s are reported.

METHOD

Case report.

RESULTS

Two genetically confirmed CMT1A patients are presented, from two unrelated families (one of British origin and the other of Brazilian origin). Both individuals had upper limb motor NCVs above 38 m/s, with values ranging from 41.9 to 45 m/s in the median nerve and from 42 to 42.3 m/s in the ulnar nerve. They presented with a very mild phenotype, with CMT Neuropathy Score version 2 (CMTNSv2) of 6 and 5, respectively. In contrast, affected family members within both kinships exhibited a classical phenotype with more severe disease manifestation (CMTNSv2 ranging from 12 to 20) and motor NCVs below 30 m/s.

CONCLUSION

These cases, although very rare, highlight the importance of testing PMP22 duplication in patients with intermediate conduction velocities.

OPM-MEG Measuring Phase Synchronization on Source Time Series: Application in Rhythmic Median Nerve Stimulation

The magnetoencephalogram (MEG) based on array optically pumped magnetometers (OPMs) has the potential of replacing conventional cryogenic superconducting quantum interference device. Phase synchronization is a common method for measuring brain oscillations and functional connectivity. Verifying the feasibility and fidelity of OPM-MEG in measuring phase synchronization will help its widespread application in the study of aforementioned neural mechanisms. The analysis method on source-level time series can weaken the influence of instantaneous field spread effect. In this paper, the OPM-MEG was used for measuring the evoked responses of 20Hz rhythmic and arrhythmic median nerve stimulation, and the inter-trial phase synchronization (ITPS) and inter-reginal phase synchronization (IRPS) of primary somatosensory cortex (SI) and secondary somatosensory cortex (SII) were analysed. The results find that under rhythmic condition, the evoked responses of SI and SII show continuous oscillations and the effect of resetting phase. The values of ITPS and IRPS significantly increase at the stimulation frequency of 20Hz and its harmonic of 40Hz, whereas the arrhythmic stimulation does not exhibit this phenomenon. Moreover, in the initial stage of stimulation, the ITPS and IRPS values are significantly higher at Mu rhythm in the rhythmic condition compared to arrhythmic. In conclusion, the results demonstrate the ability of OPM-MEG in measuring phase pattern and functional connectivity on source-level, and may also prove beneficial for the study on the mechanism of rhythmic stimulation therapy for rehabilitation.

Cognition-Enhancement Effect of Median Nerve Electrical Stimulation in Patients with Cognitive Impairment: A Retrospective Cohort Study

OBJECTIVE

People with cognitive impairment often face quality-of-life problems and require ongoing support, which has profound consequences for caregivers and society. Noninvasive brain stimulation techniques, such as median nerve electrical stimulation (MNS), have shown promising potentials in improving cognitive ability in patients with cognitive impairment. Therefore, we aimed to investigate the positive effect and safety of MNS in cognitive impairment.

METHODS

Patients diagnosed with cognitive impairment from the hospital record management system of the First Affiliated Hospital of Nanchang University from April 1, 2020, to December 31, 2022, were enrolled. Data on patients' basic characteristics, treatment records, and examination results such as the Mini-Mental State Examination (MMSE), activities of daily living (ADL), and P300 event-related potentials before and after treatment were collected.

RESULTS

Overall, 146 patients with cognitive impairment were enrolled, including 71 patients who underwent conventional therapy (standard treatment group) and 75 patients who underwent conventional therapy and MNS operation (active MNS group). Before treatment, there were no differences between the standard treatment and active MNS groups in terms of age, sex, etiology, duration of symptoms before therapy, hospital stay, whether they had undergone surgery, MMSE score, ADL score, and amplitude and latency of the P300 event-related potentials (P > 0.05). After treatment, we observed significant improvements in the MMSE score, ADL score, amplitude of P300, and decreased latency of P300 event-related potentials in both groups compared with before treatment (P < 0.05). In addition, we observed that the active MNS group showed higher MMSE and ADL scores, higher amplitude of P300 event-related potentials, and lower latency of P300 event-related potentials than the standard treatment group after treatment (P < 0.05). Furthermore, no side effects were associated with MNS operation.

CONCLUSIONS

These preliminary data provide early evidence that MNS may be a positive effect and safe method for promoting the recovery of cognitive ability in patients with cognitive impairment.

Capitate Proximal Fragment Migration Compressing the Median Nerve in Scaphocapitate Fracture: A Case Report

BACKGROUND Scaphocapitate syndrome is a rare clinical entity consisting of a combined scaphoid and capitate fracture along with a 90- or 180-degrees rotation of the proximal capitate fragment. The syndrome is scarcely described in the literature, with proximal migration of the capitate fragment being reported only by Mudgal et al in 1995. Concurrent compression of the median nerve is a highly unfortunate event, suggesting a unique case presented here. CASE REPORT We present a unique case of scaphocapitate fracture-dislocation in a 25-year-old man with volar dislocation of the capitate's fragment deep to the median nerve. X-rays and CT scan were performed and the patient was treated few hours after the injury by a hand specialist, in order to prevent median neuropathy and avascular necrosis of the fragment. Open reduction and internal fixation utilizing a Herbert screw for the scaphoid fracture and 3 additional K-wires was performed. Immediately post-operatively, the acute neurological symptoms had subsided and good reduction was acquired radiologically. One year post-operatively the patient had regained good hand and wrist functionality, with no extension or flexion ROM deficits. CONCLUSIONS Immediate intervention in a specialized center with reduction and fixation utilizing a Herbert screw and K-wires showed favorable 1-year results in our case of scaphocapitate syndrome. The impending complications of median neuropathy and capitate avascular necrosis were avoided despite the high-risk injury pattern.

Amplitude of Somatosensory Evoked Potentials (SEPs) Recorded in Short-Latency SEP Condition Is 80% of That in Giant SEP Condition

PURPOSE

Giant somatosensory evoked potentials (SEPs) with enhanced long-loop reflex (C-reflex) are useful to detect cortical motor hyperexcitability in patients with myoclonic epilepsy. The recording conditions of giant SEPs are different from those of short-latency SEPs (SSEPs). We investigated the waveform characteristics obtained for each condition.

METHODS

Forty-eight upper limbs of 24 adult normal subjects (12 men, age 35.5 ± 9.7 years [mean ± SD]) were investigated. Somatosensory evoked potentials of each subject were recorded in both conditions on the same day. The main differences in recording conditions were reference electrodes (SSEP: Fz vs. giant SEP: the earlobe electrode ipsilateral to the stimulated limb), stimulus rate (5 vs. 1 Hz), and bandpass filter (20 Hz-3 kHz vs. 1 Hz-1 kHz). Somatosensory evoked potentials were elicited by unilateral percutaneous electrical stimulation of the median nerve at the wrist with intensity of 110% of the movement threshold and recoded at C3'/C4'.

RESULTS

The amplitudes of N20 onset-N20 and N20-P25 were significantly larger in giant SEP condition than in SSEP condition ( p < 0.001). The mean + 3SD of N20-P25 amplitude was 10.0 μV in giant SEP condition and 7.8 μV in SSEP condition. The N20-P25 amplitude was significantly correlated between giant SEP condition and SSEP condition ( R = 0.64, p < 0.001). C-reflex was not elicited.

CONCLUSIONS

The amplitude of SEPs in SSEP condition is equivalent to 80% of that in giant SEP condition. The information is useful for detecting cortical hyperexcitability in various neurological disorders including myoclonic epilepsy.

Relationship between Gravidity, Parity, and Neurophysiological Features in Carpal Tunnel Syndrome (CTS) Patients with a History of Pregnancy

BACKGROUND

It is not yet clear if gravidity and parity have any relationships with the electrodiagnostic parameters of carpal tunnel syndrome (CTS).

OBJECTIVE

To determine whether there is a relationship between electrodiagnostic findings, gravidity, and parity number in CTS.

MATERIALS AND METHODS

Female patients over 18 years of age with CTS were included in this retrospective cohort study. The gravidity/parity number, median nerve compound muscle action potential (CMAP), and compound nerve action potential (CNAP) of the patients were analyzed. The two subgroups of the Boston carpal tunnel syndrome questionnaire (BCTSQ): The Symptom Severity Scale (SSS) and Functional Severity Scale (FSS) were applied to the patients. CTS patients were divided into two groups aged at first pregnancy ≤20 years and >20 years.

RESULTS

One hundred and eight CTS extremities (seven right-sided CTS, three left-sided CTS, 49 bilateral CTS) of 59 patients were included. The median (interquartile range: 25%-75%) number of gravidity, parity, and abortion were 3 (2-5), 3 (2-4), and 0 (0-0), respectively. Right-sided CTS patients at the age of first pregnancy ≤20 years had higher BCTSQ-SSS/FSS scores and median nerve CMAP latency compared to patients at the age of first pregnancy >20 years (P = 0.029 for SSS; P = 0.042 for FSS; and P = 0.041 for CMAP latency). A negative correlation was found between the gravidity/parity numbers and median nerve CNAP/CMAP amplitudes (P = 0.028/0.031, r = -0.293/-0.289 for CNAP amplitude; and P = 0.006/0.035, r = -0.363/-0.283 for CMAP amplitude).

CONCLUSION

Neurophysiological findings worsen as the number of gravidity and parity increase. Electrodiagnostic and clinical features of CTS may be worsening in females below 20 years at first pregnancy.

Efficacy of focused shockwave therapy in patients with moderate-to-severe carpal tunnel syndrome: a preliminary study

OBJECTIVE

To evaluate the efficacy of focused extracorporeal shockwave therapy for symptoms and function in patients with moderate-to-severe carpal tunnel syndrome.

DESIGN

A single-blind randomized controlled trial.

SUBJECTS

Twenty-four outpatients with moderate-to-severe carpal tunnel syndrome.

METHODS

Patients were randomly allocated into 2 groups: a focused extracorporeal shockwave therapy group and a control group. The focused extracorporeal shockwave therapy group received conservative treatment in addition to focused extracorporeal shockwave therapy with an energy flux density ranging from 0.01 to 0.15 mJ/mm2, a frequency of 4-5 Hz, and 1500 pulses per session once a week for a total of 3 sessions. The control group received only conservative treatment, which comprised gliding exercises for carpal tunnel syndrome, a night wrist splint, and lifestyle modification. The Thai version of the Boston Carpal Tunnel Questionnaire (T-BCTQ), a nerve conduction study, and ultrasonography of the median nerve cross-sectional area were performed before treatment and at 3 and 6 weeks after baseline.

RESULTS

The T-BCTQ symptom and function scores had significantly decreased in both groups, favouring focused extracorporeal shockwave therapy at all time-points. In addition, distal sensory and motor latency were significantly different between the groups at 3 weeks from baseline.

CONCLUSION

Focused extracorporeal shockwave therapy plus conservative treatment effectively provided short-term improvement in symptoms, hand function, and nerve conduction in patients with moderate-to-severe carpal tunnel syndrome compared with conservative treatment alone.

A Novel Approach to Screen for Somatosensory Evoked Potentials in Critical Care

BACKGROUND

Somatosensory evoked potentials (SSEPs) help prognostication, particularly in patients with diffuse brain injury. However, use of SSEP is limited in critical care. We propose a novel, low-cost approach allowing acquisition of screening SSEP using widely available intensive care unit (ICU) equipment, specifically a peripheral "train-of-four" stimulator and standard electroencephalograph.

METHODS

The median nerve was stimulated using a train-of-four stimulator, and a standard 21-channel electroencephalograph was recorded to generate the screening SSEP. Generation of the SSEP was supported by visual inspection, univariate event-related potentials statistics, and a multivariate support vector machine (SVM) decoding algorithm. This approach was validated in 15 healthy volunteers and validated against standard SSEPs in 10 ICU patients. The ability of this approach to predict poor neurological outcome, defined as death, vegetative state, or severe disability at 6 months, was tested in an additional set of 39 ICU patients.

RESULTS

In each of the healthy volunteers, both the univariate and the SVM methods reliably detected SSEP responses. In patients, when compared against the standard SSEP method, the univariate event-related potentials method matched in nine of ten patients (sensitivity = 94%, specificity = 100%), and the SVM had 100% sensitivity and specificity when compared with the standard method. For the 49 ICU patients, we performed both the univariate and the SVM methods: a bilateral absence of short latency responses (n = 8) predicted poor neurological outcome with 0% FPR (sensitivity = 21%, specificity = 100%).

CONCLUSIONS

Somatosensory evoked potentials can reliably be recorded using the proposed approach. Given the very good but slightly lower sensitivity of absent SSEPs in the proposed screening approach, confirmation of absent SSEP responses using standard SSEP recordings is advised.

[Neuralgic amyotrophy: an inflammatory neuropathy and its surgical treatment]

BACKGROUND

Neuralgic amyotrophy (NA) is a monofocal or oligofocal inflammatory neuropathy whose incidence has been significantly underestimated. A connection between constrictions and torsions of peripheral nerves with this disease has been increasingly established in recent years. Modern imaging techniques such as high-resolution nerve ultrasound and MR neurography have contributed to a better understanding of the pathophysiology and a better assessment of the prognosis of the disease. This has led to the concept of treating patients with such focal changes surgically in order to improve the prognosis. This review presents current ideas on the pathophysiology, clinical presentation, diagnosis and treatment of the disease.

PATIENTS AND METHODS

In a retrospective study, pre-, intra- and postoperative findings of 22 patients with 23 constrictions/torsions of peripheral nerves of the upper extremity were analysed. The patients underwent surgery at a nerve surgery centre over a period of 3.5 years (Dec. 2019-May 2023). The median nerve was most frequently affected (N=9), followed by the suprascapular nerve (N=6) and radial nerve (N=4). The axillary nerve (N=3) and the accessory nerve (N=1) were also involved. Surgical exploration revealed nerve torsions (N=9), nerve constrictions (N=5), fascicular torsions (N=12) and fascicular constrictions (N=9). Depending on the intraoperative findings, epineuriotomies (N=1), epi- and perineuriotomies (N=33), end-to-end sutures (N=2), and one epi- and one perineural suture were performed.

RESULTS

After an average follow-up of 10 months (3-28 months), 17 patients were re-examined. All of them reported a clear subjective improvement in motor deficits. Clinically and electromyographically, a reinnervation and significant increase in strength from a pre-existing strength grade of M0 to at least M3 in the vast majority of affected muscles was demonstrated in these patients.

SUMMARY

The incidence of NA continues to be underestimated and, in a significant proportion of patients, leads to permanent motor deficits, most likely due to constrictions and torsions of affected nerves. Surgical treatment is recommended as early as possible. Very good results can usually be achieved with epi- and perineuriotomy. In rare cases, end-to-end neurorrhaphy or nerve grafting is required.

[Rare nerve compression neuropathies]

UNCOMMON NERVE COMPRESSION SYNDROMES

In regard to the complex anatomical relationship of peripheral nerves and muscles, tendons, fasciae as well as their long course within those anatomical structures and additional close contact to bony structures, they are prone to suffer from local compression syndromes. Hence creating a vast majority of entrapment syndromes - well described in literature for almost every single nerve. The purpose of this article is to give an overview of symptoms, signs, diagnostic studies and treatment options, addressing especially the less known syndromes. Compression syndromes of the upper arm and shoulder region include the suprascapular nerve syndrome the compression of the axillary nerve within the spatium quadrilaterale and the compression of the long thoracic nerve at the chest wall. The upper extremity offers a variety of infrequent entrapment syndromes, as the pronator teres syndrome and anterior interosseus syndrome, both resulting from pressure to the median nerve in the forearm. Compression neuropathy in the course of the radial nerve in the distal upper extremity is also known as supinator syndrome. Guyon's canal syndrome is the ulnar side equivalent to the well-known carpal tunnel syndrome. In the case of a Cheiralgia paresthetica, a compression of a sensory branch of the superficial radial nerve can be seen. In the lower extremities, a variety of nerves especially in the groin and thigh area can be compressed as they pass through the narrow spaces between the abdominal muscles or underneath the inguinal ligament. Compression of the lateral femoral cutaneous nerve is the most common syndrome. Compression syndromes of the femoral and obturator nerves are most often iatrogenic. Pain around the knee, especially the lateral part and following orthopedic procedures of the knee, can arise from a compression or a lesion of a small infrapatellar branch of the saphenous nerve. Another probably underdiagnosed syndrome is piriformis syndrome, resulting from an entrapment of the sciatic nerve as it passes through certain muscular structures. In the distal lower extremity, the peroneal and tibial nerves can be compressed at multple sites, clinically known as peroneal nerve paralysis resulting from nerve compression around the fibular head, the anterior and posterior tarsal tunnel syndrome, and Morton's metatarsalgia.

Anti-cancer therapeutic agents and carpal tunnel syndrome: Clinical, electrodiagnostic, and ultrasound findings in seven patients

INTRODUCTION

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy and rarely develops after drug therapy. This study describes the clinical, electrodiagnostic (EDX), and ultrasound (US) findings in seven patients who experienced CTS due to anti-cancer therapeutic agents.

METHODS

All patients underwent EDX testing, and four patients had an US study.

RESULTS

CTS occurred in four patients with aromatase inhibitors, two with immune checkpoint inhibitors, and one with a selective estrogen receptor modulator. The mean duration between initiation of the anti-cancer therapeutic agents and symptom onset was 6 weeks (range: 2-12 weeks). Decreased digit sensation was noted in all patients; wasting and weakness of the abductor pollicis brevis (APB) was observed in three (42.8%) patients. The compound muscle action potentials (CMAP) of the APB and sensory nerve action potentials of the second or third digit could not be recorded in two (28.5%) and four (57.1%) patients, respectively. The needle EMG detected fibrillations and positive sharp waves in the APB in two patients. The motor unit potentials of the APB were decreased with large polyphasics in three (42.8%) patients. Of the four patients who underwent US testing, all had increased cross-sectional area of the median nerve at the carpal tunnel inlet, three (75%) had thenar muscle atrophy, and two (50%) had a loss of fascicular pattern. Three (42.8%) patients underwent a CTR.

CONCLUSIONS

Physicians should be cognizant of the relationship between anti-cancer therapeutic agents and CTS. EDX studies and US play important roles in the diagnostic assessment of such patients.

Provocative changes in nerve conductions: Fact or fiction?

At times electrodiagnostic medical consultants (EMCs) are asked to perform studies in both a neutral position, and then again after the patient is in a provocative position that exacerbates symptoms, to assess for measurable electrophysiologic changes. While this approach might seem initially appealing, particularly when standard studies are not effective at diagnosis, empiric studies in several conditions have been unimpressive. Studies in median neuropathy at the wrist, thoracic outlet syndrome, piriformis syndrome, and radial tunnel syndrome have failed to demonstrate reproducible changes in nerve conduction studies in positions that exacerbate symptoms. Furthermore, there is lack of a plausible pathophysiologic mechanism for producing both measurable and rapidly reversible electrophysiologic changes after just a few minutes, or less, of compression. Axon loss and demyelination would not be rapidly reversible, and positional changes of 2 min or less (the durations generally studied) would be insufficient to produce measurable nerve ischemia. Last, we have gained a greater appreciation for how much nerves move within limbs with changes in joint position; this movement can lead to misleading changes in nerve conduction studies. It is thus appropriate to conclude that testing nerve conduction in provocative or symptomatic positions adds no value to electrodiagnostic testing.

Natural evolution of idiopathic carpal tunnel syndrome with respect to wrist and hand anthropometry: A prospective cohort study

OBJECTIVE

A greater wrist depth/width ratio and wrist depth/palm length ratio are known risk factors for carpal tunnel syndrome. We hypothesized that these parameters might also predict progression in patients who were not surgically treated.

METHODS

Seventy-eight patients with moderately severe idiopathic carpal tunnel syndrome of at least 10 months duration at recruitment, who declined surgical treatment and steroid injection, underwent repeated neurophysiological assessments after 3 years. A > 10% increase in median SNAP latency was taken as evidence of significant deterioration.

RESULTS

Patients with a wrist ratio ≥ 0.72 showed a statistically significant deterioration in SNAP latency from 5.46 (SD 2.09) to 7.16 (SD 1.56) ms and in SNAP amplitude from 30.19 (SD 13.8) to 16.62 (SD 14.42) µv. For those with a wrist-to-palm ratio ≥ 0.42, SNAP latency deteriorated from 5.27 (SD 1.21) to 7.1 (SD 1.52) ms, and amplitude from 32.78 (SD 13.76) to 19.45 (SD 16.62) µv. Patients with lower ratios did not show significant changes in any neurophysiological parameter. The relative risk of significant deterioration in SNAP latency in patients with a wrist ratio ≥ 0.72 was 2.04 (95% CI 1.27-3.27).

CONCLUSION

In untreated idiopathic carpal tunnel syndrome, patients with larger wrist and wrist-to-palm ratios are more likely to show neurophysiological progression.

National trends in the initial diagnosis and management of carpal tunnel syndrome: results from the ELECTS (ELEctrophysiology in Carpal Tunnel Syndrome) study

INTRODUCTION

The optimal role of nerve conduction studies (NCS) in management of carpal tunnel syndrome (CTS) is unclear, with no standardised guidance. This study aimed to identify variation in practice in the initial diagnosis of patients with suspected CTS, alongside evaluating how NCS findings influence clinical decision making.

METHODS

A national multicentre collaborative survey was conducted in 2021. All centres providing surgery for CTS were invited to participate, primarily via social media. All middle-senior grade orthopaedic/plastic surgeons and advanced care practitioners that regularly manage new referrals for suspected CTS were eligible to respond. Local representatives at each participating site submitted their responses to a central team who collated and analysed the results.

RESULTS

A total of 137 healthcare professionals responded from 18 UK NHS Trusts. Of these 137, 124 (91%) reported not employing any validated clinical questionnaires in their routine practice, preferring to rely on clinical diagnosis and/or NCS if available, whereas 84 (61%) utilised NCS to aid diagnosis, with significant differences among professionals with differing experience (p < 0.01). The most common methods for determining the severity of CTS were history, examination and NCS. In symptomatic CTS with confirmatory NCS, over 50% of clinicians would choose surgical decompression as their first-line intervention. In cases of either negative NCS or atypical presentation, 37% and 51%, respectively, would consider conservative management (e.g. splintage) or steroid injection first line.

CONCLUSIONS

With growing waiting lists for NCS and surgery, national consensus guidelines should be developed to support decision making, while maximising efficient utilisation of increasingly constrained resources.

Trigeminal or peripheral nerve stimulation improves functional outcomes of nerve recovery in a rodent forelimb gap repair model

BACKGROUND

The hypothesis of this study was that trigeminal nerve stimulation (TNS) or peripheral nerve stimulation (PNS) could improve functional outcomes of peripheral nerve injury in a rat forelimb model when compared to control rats not receiving electrical stimulation (ES). While PNS is known to improve outcomes after nerve surgery, the role of TNS has not been explored.

METHODS

Lewis rats were trained to perform a reach and grasp task before receiving a 2 mm gap repair of the ulnar and median nerves and randomized into four treatment groups: (1) sham injury, (2) nerve injury with sham ES, (3) nerve injury with PNS, and (4) nerve injury with TNS. Functional motor (median pull force and percent success in motor task) and sensory metrics (forelimb paw withdrawal thresholds) were collected both pre-injury and throughout rehabilitation. Nerves stained using Gomori's trichrome were assessed quantitatively and qualitatively.

RESULTS

The sham ES group did not recover their pre-injury baseline functional outcomes. In contrast, the TNS and PNS groups fully recovered following injury, with no difference in functional outcomes between the pre-injury baseline and the final week of rehabilitation (P > 0.05, all). Histomorphology results demonstrated no quantitative difference, but qualitative differences in architecture were evident.

CONCLUSIONS

Electrical stimulation of the trigeminal nerve or the injured nerve improved the functional outcomes of nerve regeneration in rodents. Histomorphology results of nerves from the TNS group support the proposed central mechanisms. This is an important step in translating this therapy as an adjunct, non-invasive treatment for high, mixed nerve injuries in humans.

Exploration of sensations evoked during electrical stimulation of the median nerve at the wrist level

Objective.Nerve rehabilitation following nerve injury or surgery at the wrist level is a lengthy process during which not only peripheral nerves regrow towards receptors and muscles, but also the brain undergoes plastic changes. As a result, at the time when nerves reach their targets, the brain might have already allocated some of the areas within the somatosensory cortex that originally processed hand signals to some other regions of the body. The aim of this study is to show that it is possible to evoke a variety of somatotopic sensations related to the hand while stimulating proximally to the injury, therefore, providing the brain with the relevant inputs from the hand regions affected by the nerve damage.Approach.This study included electrical stimulation of 28 able-bodied participants where an electrode that acted as a cathode was placed above the Median nerve at the wrist level. The parameters of electrical stimulation, amplitude, frequency, and pulse shape, were modulated within predefined ranges to evaluate their influence on the evoked sensations.Main results.Using this methodology, the participants reported a wide variety of somatotopic sensations from the hand regions distal to the stimulation electrode.Significance.Furthermore, to propose an accelerated stimulation tuning procedure that could be implemented in a clinical protocol and/or standalone device for providing meaningful sensations to the somatosensory cortex during nerve regeneration, we trained machine-learning techniques using the gathered data to predict the location/area, naturalness, and sensation type of the evoked sensations following different stimulation patterns.

Selective peripheral nerve recording using simulated human median nerve activity and convolutional neural networks

BACKGROUND

It is difficult to create intuitive methods of controlling prosthetic limbs, often resulting in abandonment. Peripheral nerve interfaces can be used to convert motor intent into commands to a prosthesis. The Extraneural Spatiotemporal Compound Action Potentials Extraction Network (ESCAPE-NET) is a convolutional neural network (CNN) that has previously been demonstrated to be effective at discriminating neural sources in rat sciatic nerves. ESCAPE-NET was designed to operate using data from multi-channel nerve cuff arrays, and use the resulting spatiotemporal signatures to classify individual naturally evoked compound action potentials (nCAPs) based on differing source fascicles. The applicability of this approach to larger and more complex nerves is not well understood. To support future translation to humans, the objective of this study was to characterize the performance of this approach in a computational model of the human median nerve.

METHODS

Using a cross-sectional immunohistochemistry image of a human median nerve, a finite-element model was generated and used to simulate extraneural recordings. ESCAPE-NET was used to classify nCAPs based on source location, for varying numbers of sources and noise levels. The performance of ESCAPE-NET was also compared to ResNet-50 and MobileNet-V2 in the context of classifying human nerve cuff data.

RESULTS

Classification accuracy was found to be inversely related to the number of nCAP sources in ESCAPE-NET (3-class: 97.8% ± 0.1%; 10-class: 89.3% ± 5.4% in low-noise conditions, 3-class: 70.3% ± 0.1%; 10-class: 52.5% ± 0.3% in high-noise conditions). ESCAPE-NET overall outperformed both MobileNet-V2 (3-class: 96.5% ± 1.1%; 10-class: 84.9% ± 1.7% in low-noise conditions, 3-class: 86.0% ± 0.6%; 10-class: 41.4% ± 0.9% in high-noise conditions) and ResNet-50 (3-class: 71.2% ± 18.6%; 10-class: 40.1% ± 22.5% in low-noise conditions, 3-class: 81.3% ± 4.4%; 10-class: 31.9% ± 4.4% in high-noise conditions).

CONCLUSION

All three networks were found to learn to differentiate nCAPs from different sources, as evidenced by performance levels well above chance in all cases. ESCAPE-NET was found to have the most robust performance, despite decreasing performance as the number of classes increased, and as noise was varied. These results provide valuable translational guidelines for designing neural interfaces for human use.

Somatosensory pathway dysfunction in patients with amyotrophic lateral sclerosis in a completely locked-in state

OBJECTIVE

To investigate somatosensory pathway function in patients with amyotrophic lateral sclerosis (ALS) dependent on invasive ventilation and in a completely locked-in state (CLIS).

METHODS

We examined median nerve somatosensory evoked potentials (SEPs) in 17 ALS patients in a CLIS, including 11 patients with sporadic ALS, one with familial ALS with genes not examined, four with a Cu/Zn superoxide-dismutase-1 (SOD1) gene variant (Val118Leu, Gly93Ser, Cys146Arg), and one with a fused-in-sarcoma gene variant (P525L). We evaluated N9, N13, N20 and P25, and central conduction time (CCT); the data were compared with those of 73 healthy controls.

RESULTS

N20 and N13 were abolished in 12 and 10 patients, and their latencies was prolonged in four and three patients, respectively. The CCT was prolonged in five patients with measurable N13 and N20. Two patients with SOD1 gene mutations had absent or slightly visible N9. Compared to the CCT and latencies and amplitudes of N13 and N20 in the controls, those in the patient cohort were significantly abnormal.

CONCLUSIONS

The central somatosensory pathway is severely involved in patients with ALS in a CLIS.

SIGNIFICANCE

Our findings suggest that median nerve SEP cannot be utilized for communication in patients with ALS in a CLIS.

Carpal Tunnel Syndrome in Athletes Who Compete in Wheelchair Sport: A Scoping Review

ABSTRACT

The purpose of this review was to understand the research on carpal tunnel syndrome in athletes who compete in wheelchair sport. Eight articles were identified using the search strategy. The most common sport evaluated was wheelchair basketball ( N = 4). Most athletes were male and were diagnosed with a spinal cord injury. Different clinical and electrodiagnostic criteria have been used to diagnose carpal tunnel syndrome. Two studies incorporated ultrasound into the clinical evaluation of median nerve pathology. The duration of disability and wheelchair use were associated with increased risk of carpal tunnel syndrome in four studies. There was no association between training load and the prevalence of carpal tunnel syndrome. No study has explored the functional implications of carpal tunnel syndrome on sports participation and performance. No study has assessed the prevention and treatment of carpal tunnel syndrome in individuals who compete in wheelchair sport. This review provides an understanding of the important diagnostic tools, and demographic and training risk factors to consider when evaluating para-athletes for carpal tunnel syndrome and highlights areas for future research.

The prevalence of double- and multiple crush syndromes in patients surgically treated for peripheral nerve compression in the upper limb

OBJECTIVE

The double crush syndrome describes a condition characterized by multifocal entrapment of a nerve. In the upper limb, the high prevalence of carpal tunnel syndrome makes it a common diagnosis of assumption in the setting of median neuropathy. More proximal compressions may tend to be overlooked, under-diagnosed and under-treated in the population. This study aims to map the prevalence of peripheral upper limb nerve compressions among patients undergoing peripheral nerve decompression.

METHODS

A prospective case series was conducted on 183 patients undergoing peripheral nerve decompression in a private hand surgery clinic. Level(s) of nerve compression in the median, ulnar and radial nerves were determined by history and physical examination. The prevalence of each nerve compression syndrome or combination of syndromes was analyzed.

RESULTS

A total of 320 upper limbs in 183 patients were analyzed. A double crush of the median nerve at the levels of the lacertus fibrosus and carpal tunnel was identified in 78% of upper limbs with median neuropathy, whereas isolated lacertus syndrome and carpal tunnel syndrome were present in only 5% and 17% of affected limbs respectively. Cubital tunnel syndrome affected 12.5% of upper limbs, and 80% of these had concomitant lacertus and carpal tunnel syndromes, compared to only 7.5% with isolated cubital tunnel syndrome.

CONCLUSION

A high prevalence should prompt clinicians towards more routine assessment for double crush syndrome to avoid misdiagnosis, inadequate treatment, recurrence, and revision surgeries.

Mechanisms, interventions at risk and clinical presentation of iatrogenic nerve lesions in trauma patients

BACKGROUND

Iatrogenic nerve lesions during surgical interventions are avoidable complications that may cause severe functional impairment. Hereby, awareness of physicians and knowledge of structures and interventions at risk is of utmost importance for prevention. As current literature is scarce, we evaluated all patients treated surgically due to peripheral nerve injuries in our specialized nerve center for the presence of iatrogenic nerve lesions.

METHODS

We evaluated a total of 5026 patients with peripheral nerve injuries treated over a time period of 8 years in our facility for the prevalence of iatrogenic nerve injuries, their clinical presentations, time to treatment, mechanisms and intraoperative findings on nerve continuity.

RESULTS

A total of 360 (6.1%) patients had an iatrogenic cause resulting in 380 injured nerves. 76.6% of these lesions affected the main branch of the injured nerve, which were mainly the radial (30.5%), peroneal (13.7%) and median nerve (10.3%). After a mean delay of 237 ± 344 days, patients presented 23.2% with a motor and 27.9% with a mixed sensory and motor deficit. 72.6% of lesions were in-continuity lesions. Main interventions at risk are displayed for every nerve, frequently concerning osteosyntheses but also patient positioning and anesthesiologic interventions.

DISCUSSION

Awareness of major surgical complications such as iatrogenic nerve injuries is important for surgeons. An often-seen trivialization or "watch and wait" strategy results in a huge delay for starting an adequate therapy. The high number of in-continuity lesions mainly in close proximity to osteosyntheses makes diagnosis and treatment planning a delicate challenge, especially due to the varying clinical presentations we found. Diagnostics and therapy should therefore be performed as early as possible in specialized centers capable of performing nerve repair as well as salvage therapies.

Clinical efficacy of electroacupuncture-like magnetic therapy compared to conventional transcutaneous electrical nerve stimulation in individuals with carpal tunnel syndrome

This study aimed to evaluate the clinical efficacy of an electroacupuncture-like magnetic therapy (ELMT) and conventional transcutaneous electrical nerve stimulation (TENS) in patients with carpal tunnel syndrome (CTS). A prospective randomized controlled trial in single-centre was conducted. Thirty-four CTS patients confirmed by electrodiagnostic study were randomized into TENS or ELMT group and completed a six-week treatment program. TENS or ELMT treatment was applied on acupuncture point PC-6 (Neiguan) and one selected hand acupoint. Therapeutic exercises were also included after the electrophysical modality. Their physical signs, motor and sensory performances, Boston Carpal Tunnel Questionnaire (BCTQ) scores, and results of electrodiagnostic study were evaluated. After treatments, both groups demonstrated significantly decreased BCTQ scores and positive rate of Tinel's sign in the major symptomatic side, which indicated improvements in the symptom severity and physical functions. Significant increases in distal sensory amplitude and nerve conduction velocity of the median nerve were only found in the ELMT group. Our study found either conventional TENS or ELMT plus therapeutic exercises could improve the symptomatology and physical provocation sign of CTS. The ELMT has additional improvement in the nerve conduction in patients with CTS.

High frequency of carpal tunnel syndrome and associated factors: A cross-sectional study in Peruvian workers from agro-export industry

Carpal tunnel syndrome (CTS) is a peripheral mononeuropathy caused by compression of the median nerve at the wrist and has been reported in workers who perform repetitive movements that involve actions of sustained grasping of vibrating objects. We carried out a cross-sectional analytical study in March 2018 to identify the factors associated with the CTS among workers of agro-export companies in Ica-Peru. CTS confirmation in our study was based on having at least 1 positive screening test (Tinel or Phalen) and a presumptive result of CTS by the Kamath and Stothard Questionnaire. We carried out 4 Poisson regression models to evaluate the factors associated with CTS based on epidemiological and statistical criteria. We enrolled 112 agro-export workers in production (42.0%), packing (35.7%), and administration (22.3%) working areas. The CTS frequency in Peruvian agro-export workers in production, packing, and administrative working area were 78.7%, 45.0%, and 28.0%, respectively. The bivariate analysis found a relationship between the CTS with age, female sex, sports practice, job seniority in the working area (year), and repetitive wrist movements (hours per day). In the multivariate analysis, only job seniority in the working area (year) and repetitive wrist movements maintained their association with CTS. Occupational factors are significantly associated with a high frequency of CTS, such as job seniority in the working area (year) and repetitive wrist movements in agro-export workers. Surveillance programs should be held to prevent, reduce, and monitor workers' health status.

Anatomical Variations of the Musculocutaneous Nerve in the Human Fetus

OBJECTIVES

Knowing the motor branches and variations of the musculocutaneous nerve to the muscles along its course will facilitate the treatment of flexor spasticity and supracondylar fractures of the humerus in order to minimize nerve lesion. In fetal cadavers, the purpose of our study was to determine the number and course of the formation variations and motor branches of the musculocutaneous nerve. The significance of studying fetal nerve variations is due to injury to the brachial plexus roots during birth.

METHODS

Our study was conducted using the anatomical dissection technique on 102 upper limbs from 51 fetuses ages ranged from 17 to 40 weeks. Throughout its course, the variations and motor branches of the musculocutaneous nerve were analyzed.

RESULTS

In 13.7% of cases, the musculocutaneous nerve did not pierce the coracobrachialis. The musculocutaneous nerve gave the muscles 1-3 motor branches. Additionally, motor branches terminated with 1-7 fringes. The biceps brachii motor branches of the musculocutaneous nerve were typed. Accordingly, 15.6% were type 1A, 3.9% were type 1B, 35.4% were type 1C, and 19.6% were type 1D. It was determined that 23.5% of the extremities were type 2 and that 1.9% were type 3. The distance between the musculocutaneous nerve's motor branches and the acromion was proportional to the arm's length. There were no statistically significant differences between the sides and genders for any measurement.

CONCLUSIONS

Our study's findings will aid in the diagnosis and treatment of pediatrics, orthopedics, surgical sciences, and radiology conditions. It reduces the risk of iatrogenic injury and postoperative complications. We also believe that our research will serve as a resource for anatomists and other scientists.

Intraoperative immediate strength recovery following lacertus fibrosus release in patients with proximal median nerve compression at the elbow

PURPOSE

In the literature, we find that patients with lacertus syndrome (LS), proximal median nerve compression at the elbow, present subjective improvement of thumb, and index flexion strength after lacertus fibrosus (LF) release. The aim of this study is to objectively evaluate the immediate change in intraoperative flexion strength after LF release.

METHOD

We retrospectively reviewed prospectively collected data of a cohort of 24 patients with a double crush syndrome of the median nerve with no response to conservative treatment. All patients had surgery with LF and carpal tunnel release (CTR) under wide-awake local anaesthesia and no tourniquet (WALANT) and were evaluated intraoperatively with a dynamometer immediately before and after LF release. Flexor digitorum profundus of the second finger (FDP2) and Flexor pollicis longus (FPL) were tested in peak strength to failure. The primary outcome was the percentage of change in strength before and after the release in both assessed muscles. CTR was done after evaluating the change in flexor strength.

RESULTS

A percentage of 79.2 women with an average age of 43.3 years. The average strength of FDP2 before LF release was 15.5 pounds (lbs.) (7.0 kg) (SD, 7.2 lbs (3.3 kg)) and 27.1 lbs. (12.2 kg) (SD, 7.1 lbs. (3.2 kg)) after LF release, which corresponds to a 96% (SD, 70%) change in strength (p=0.000). For FPL, the average pre-release strength was 17.7 lbs. (8.0kg) (SD, 4.8 lbs. (2.2 kg)) and 27.4 lbs. (12.4 kg) (SD, 5.2 lbs. (2.4 kg)) post-release, this corresponded to a 65% (SD, 38%) change in strength (p=0.000).

CONCLUSIONS

Peak strength to failure in FDP2 and FPL has an immediate significant recovery after LF surgical release in patients with Lacertus syndrome.

LEVEL OF EVIDENCE

IV, retrospective study.

Touch localization after nerve repair in the hand: insights from a new measurement tool

Errors of touch localization after hand nerve injuries are common, and their measurement is important for evaluating functional recovery. Available empirical accounts have significant methodological limitations, however, and a quantitatively rigorous and detailed description of touch localization in nerve injury is lacking. Here, we develop a new method of measuring touch localization and evaluate its value for use in nerve injury. Eighteen patients with transection injuries to the median/ulnar nerves and 33 healthy controls were examined. The hand was blocked from the participant's view and points were marked on the volar surface using an ultraviolet (UV) pen. These points served as targets for touch stimulation. Two photographs were taken, one with and one without UV lighting, rendering targets seen and unseen, respectively. The experimenter used the photograph with visible targets to register their locations, and participants reported the felt position of each stimulation on the photograph with unseen targets. The error of localization and its directional components were measured, separate from misreferrals-errors made across digits, or from a digit to the palm. Nerve injury was found to significantly increase the error of localization. These effects were specific to the territory of the repaired nerve and showed considerable variability at the individual level, with some patients showing no evidence of impairment. A few patients also made abnormally high numbers of misreferrals, and the pattern of misreferrals in patients differed from that observed in healthy controls.NEW & NOTEWORTHY We provide a more rigorous and comprehensive account of touch localization in nerve injury than previously available. Our results show that touch localization is significantly impaired following median/ulnar nerve transection injuries and that these impairments are specific to the territory of the repaired nerve(s), vary considerably between patients, and can involve frequent errors spanning between digits.

Second Harmonic Generation Microscopy as a Novel Intraoperative Assessment of Rat Median Nerve Injury

PURPOSE

Nerves that are functionally injured but appear macroscopically intact pose the biggest clinical dilemma. Second Harmonic Generation (SHG) Microscopy may provide a real-time assessment of nerve damage, with the ultimate goal of allowing surgeons to accurately quantify the degree of nerve damage present. The aim of this study was to demonstrate the utility of SHG microscopy to detect nerve damage in vivo in an animal model.

METHODS

Ten Sprague-Dawley rats were anesthetized and prepared for surgery. After surgical exposure and using a custom-made stretch applicator, the right median nerves were stretched by 20%, corresponding to a high strain injury, and held for 5 minutes. The left median nerve served as a sham control (SC), only being placed in the applicator for 5 minutes with no stretch. A nerve stimulator was used to assess the amount of stimulation required to induce a flicker and contraction of the paw. Nerves were then imaged using a multiphoton laser scanning microscope.

RESULTS

Immediately after injury (day 0), SHG images of SC median nerves exhibited parallel collagen fibers with linear, organized alignment. In comparison with SC nerves, high strain nerves demonstrated artifacts indicative of nerve damage consisting of wavy, undulating fibers with crossing fibers and tears, as well as a decrease in the linear organization, which correlated with an increase in the mean stimulation required to induce a flicker and contraction of the paw.

CONCLUSIONS

Second Harmonic Generation microscopy may provide the ability to detect an acute neural stretch injury in the rat median nerve. Epineurial collagen disorganization correlated with the stimulation required for nerve function.

CLINICAL RELEVANCE

In the future, SHG may provide the ability to visualize nerve damage intraoperatively, allowing for better clinical decision-making. However, this is currently a research tool and requires further validation before translating to the clinical setting.

Comparison of Patient-Reported Outcomes With or Without Prophylactic Carpal Tunnel Release After Distal Radius Fracture Stabilization

Distal radius fractures (DRFs) are frequently complicated by acute carpal tunnel syndrome (CTS), which, if unrecognized, can cause permanent median neuropathy. Some surgeons recommend "prophylactic" carpal tunnel release (CTR) during open reduction and internal fixation (ORIF) of DRF. Patient-reported outcomes (PROs) and safety data regarding prophylactic vs symptomatic CTR strategies during DRF fixation are lacking. We conducted a retrospective review of two management strategies for DRFs at our institution (2017 to 2019). Group 1 consisted of patients operated on by two surgeons performing ORIF and symptomatic CTR only for acute CTS. Group 2 consisted of patients operated on by a third surgeon performing ORIF and prophylactic CTR on all patients irrespective of median nerve symptoms. The PROs included QuickDASH Wrist and PROMIS physical/mental health preoperatively vs at final follow-up. Demographic information, complications, and return to the operating room were recorded. Group 1 (36 patients) and group 2 (76 patients) were demographically similar. The mechanism of injury was more severe in group 1 (P<.05), but preoperative PROs were similar between the two groups. Eight patients (22.2%) in group 1 had symptomatic CTR for acute CTS. Significant improvement occurred within both groups from preoperative to final follow-up for PROMIS physical function and QuickDASH Wrist scores (P<.05). Intergroup PROs were not significantly different at either time point. One patient in group 1 (2.8%) and 2 patients in group 2 (2.6%) returned to the operating room due to median nerve symptoms (P>.05). A prophylactic CTR strategy is not associated with improved PROs compared with a symptomatic strategy during ORIF of DRF. [Orthopedics. 2023;46(6):e362-e368.].

Utility of Median-to-Ulnar Sensory Comparative Nerve Conduction Study to Increase Diagnostic Accuracy in Mild Carpal Tunnel Syndrome

Electro-physiological diagnosis of mild Carpal Tunnel Syndrome (CTS) based on traditional median motor and sensory studies are often inconclusive. Therefore, we wanted to investigate the utility of Median-to-Ulnar Sensory Conduction studies in diagnosis of mild CTS. Data from Nerve conduction study (NCS) of 82 cases with symptoms suggestive of CTS from September 2017 to October 2020 attending electrophysiology department of Mount Adora Hospital, Sylhet, Bangladesh was selected for study. About 54(66.0%) out of 82 symptomatic patients were diagnosed as CTS by the conventional method, and 28(34.0%) patients required further investigation as their test report were found to be inconclusive. combining methods showed 70(85.37%) were found to be positive and 12(14.63%) were negative in comparison study. Thus, it can be concluded that those patients found to be negative in conventional methods; comparison method is an option for diagnostic confirmation.

Ultrasound morphometry of the cervical vagus nerve for daily clinical practice: Reference values for cross sectional area and fascicle count

INTRODUCTION

High resolution ultrasound (US) of the cervical vagus nerve (CVN) is clinically relevant in the diagnostic workup and during neurostimulation therapy of several neurologic diseases. This prospective study aims to provide reference data of the cross-sectional area (CSA) and fascicle count of the normal CVN and to investigate their possible association with anthropometric data in a large cohort of patients.

METHODS

A total of 657 CVNs in 330 individuals without history of neurological disease were examined using US (7-15Mhz). The CVN fascicle count and CSA inside the hyperechoic epineurium at the level of the thyroid lobes were measured. Three CSA measurements were performed to calculate the mean value. Anthropometric data were recorded.

RESULTS

The mean fascicle count was 2.4 ± 1.1 (right) and 2 ± 1 (left) (paired t- test, p < 0.001). Two CVN patterns were identified: A single hypoechoic fascicular structure (26.2 % right, 36.3 % left) and a honeycomb structure of 2-6 discrete fascicles (72.3 % right, 63.7 % left). Right CVN mean CSA was larger compared to left (2.3 ± 1 mm2 and 1.8 ± 0.8 mm2 respectively, t-test, p-0.000). There was no difference in the CSA values between sex and no correlation to age or height. A positive correlation between the CSA and weight and BMI was found (Pearson's correlation, p = 0.01 right and p = 0.05 left).

CONCLUSION

The right CVN has larger CSA and contains more fascicles than the left. CVN is usually mono- or oligo-fascicular with a honeycomb appearance. The CSA increased with increasing BMI but no age and sex specific differences were noted.

F-waves persistence in peripheral sensory syndromes

BACKGROUND

The distinction between sensory neuronopathies (SN), which is by definition purely sensory, and sensory polyneuropathies (SP) and sensory multineuropathies (SM) is important for etiologic investigation and prognosis estimation. However, this task is often challenging in clinical practice. We hypothesize that F-wave assessment might be helpful, since it is able to detect subtle signs of motor involvement, which are found in SP and SM, but not in SN.

OBJECTIVE

The aim of the present study was to determine whether F-waves are useful to distinguish SN from SP and SM.

METHODS

We selected 21 patients with SP (12 diabetes mellitus, 4 transthyretin familial amyloid polyneuropathy, 4 others), 22 with SM (22 leprosy), and 26 with SN (13 immune-mediated, 10 idiopathic, 3 others) according to clinical-electrophysiological-etiological criteria. For every subject, we collected data on height and performed 20 supramaximal distal stimuli in median, ulnar, peroneal, and tibial nerves, bilaterally, to record F-waves. Latencies (minimum and mean) and persistences were compared across groups using the Kruskal-Wallis and Bonferroni tests. P-values < 0.05 were considered significant.

RESULTS

All groups were age, gender, and height-matched. Overall, there were no significant between-group differences regarding F-wave latencies. In contrast, F-wave persistence was able to stratify the groups. Peroneal F-wave persistence was higher, bilaterally, in the SN group compared to SM and SP (p < 0.05). In addition, F-waves persistence of the ulnar and tibial nerves was also helpful to separate SN from SP (p < 0.05).

CONCLUSION

F-wave persistence of the peroneal nerves might be an additional and useful diagnostic tool to differentiate peripheral sensory syndromes.

Schmerzen nach Verwendung eines Chitosan-Neurotubes bei Medianusverletzung

Die Erstvorstellung der 29-jährigen Patientin ohne relevante internistische Vorerkrankungen erfolgte dreieinhalb Jahre nach einem Stolpersturz in eine Glasscheibe. Hierbei zog sie sich eine Schnittverletzung beugeseits distal am rechten Unterarm zu. Bei der Erstversorgung wurde lediglich die durchtrennte Flexor-carpi-radialis-Sehne adressiert. Die vollständige Durchtrennung des N. medianus, der langen Daumenbeugesehne und der oberflächlichen Beugesehne des Mittelfingers (FDS III) wurden erst nach zehn Wochen erkannt, als die Patientin nach der Ruhigstellung bei der ergotherapeutischen Beübung eine persistierende Asensibilität im Medianusgebiet einhergehend mit Neuromschmerzen sowie eine Bewegungseinschränkung des Daumens beklagte.

A double-blind, sham-controlled, trial of home-administered rhythmic 10-Hz median nerve stimulation for the reduction of tics, and suppression of the urge-to-tic, in individuals with Tourette syndrome and chronic tic disorder

Tourette syndrome (TS) and chronic tic disorder (CTD) are neurological disorders of childhood onset characterized by the occurrence of tics; repetitive, purposeless, movements or vocalizations of short duration which can occur many times throughout a day. Currently, effective treatment for tic disorders is an area of considerable unmet clinical need. We aimed to evaluate the efficacy of a home-administered neuromodulation treatment for tics involving the delivery of rhythmic pulse trains of median nerve stimulation (MNS) delivered via a wearable 'watch-like' device worn at the wrist. We conducted a UK-wide parallel double-blind sham-controlled trial for the reduction of tics in individuals with tic disorder. The device was programmed to deliver rhythmic (10 Hz) trains of low-intensity (1-19 mA) electrical stimulation to the median nerve for a pre-determined duration each day, and was intended to be used by each participant in their home once each day, 5 days each week, for a period of 4 weeks. Between 18th March 2022 and 26th September 2022, 135 participants (45 per group) were initially allocated, using stratified randomization, to one of the following groups; active stimulation; sham stimulation or to a waitlist (i.e. treatment as usual) control group. Recruited participants were individuals with confirmed or suspected TS/CTD aged 12 years of age or upward with moderate to severe tics. Researchers involved in the collection or processing of measurement outcomes and assessing the outcomes, as well as participants in the active and sham groups and their legal guardians were all blind to the group allocation. The primary outcome measure used to assess the 'offline' or treatment effect of stimulation was the Yale Global Tic Severity Scale-Total Tic Severity Score (YGTSS-TTSS) assessed at the conclusion of 4 weeks of stimulation. The primary outcome measure used to assess the 'online' effects of stimulation was tic frequency, measured as the number of tics per minute (TPM) observed, based upon blind analysis of daily video recordings obtained while stimulation was delivered. The results demonstrated that after 4-week stimulation, tic severity (YGTSS-TTSS) had reduced by 7.1 points (35 percentile reduction) for the active stimulation group compared to 2.13/2.11 points for the sham stimulation and waitlist control groups. The reduction in YGTSS-TTSS for the active stimulation group was substantially larger, clinically meaningful (effect size = .5) and statistically significant (p = .02) compared to both the sham stimulation and waitlist control groups, which did not differ from one another (effect size = -.03). Furthermore, blind analyses of video recordings demonstrated that tic frequency (tics per minute) reduced substantially (-15.6 TPM) during active stimulation compared to sham stimulation (-7.7 TPM). This difference represents a statistically significant (p < .03) and clinically meaningful reduction in tic frequency (>25 percentile reduction: effect size = .3). These findings indicate that home-administered rhythmic MNS delivered through a wearable wrist-worn device has the potential to be an effective community-based treatment for tic disorders.

Variation of the brachial artery emerging through an opening in the median nerve: a case report

The median nerve maintains a close relationship with the brachial artery in the upper limb. Variability in the formation and distribution of upper extremity vessels is frequently encountered during donor body dissections or surgical procedures. This case presents a rare anatomical variation of the brachial artery emerging through an opening in the median nerve. The median nerve formed a small opening without the contribution from additional nerve roots and the remaining vasculature of the upper limb was otherwise normal. An abnormal arrangement of a neurovascular bundle in the arm can cause sensory and motor issues, as well as vascular implications. This variation has clinical significance in surgical interventions and potentially daily functioning. To our knowledge, this is the first report of a small median nerve opening pierced by the brachial artery.

Anatomical proposal of local anesthesia injection for median nerve block in treating hyperhidrosis with botulinum neurotoxin

INTRODUCTION

Hyperhidrosis, causing excessive sweat, can be treated with Botulinum neurotoxin injection. Botulinum toxin, an effective and safe treatment for hyperhidrosis, unfortunately involves significant pain due to multiple injections. This study aims to propose a more efficient and less painful approach to nerve blocks for relief, by identifying optimal injection points to block the median nerve, thereby enhancing palmar hyperhidrosis treatment.

METHODS

This study, involving 52 Korean cadaver arms (mean age 73.5 years), measured the location of the median nerve relative to the transverse line at the pisiform level to establish better nerve block injection sites.

RESULTS

In between the extensor carpi radialis and palmaris longus, the median nerve was located at an average distance of 47.39 ± 6.43 mm and 29.39 ± 6.43 mm from the transverse line at the pisiform level.

DISCUSSION

To minimize discomfort preceding the botulinum neurotoxin injection, we recommend the optimal injection site for local anesthesia to be located 4 cm distal to the transverse line of the pisiform, within the tendons of the palmaris longus and flexor carpi radialis muscles.

In vivo biomechanical responses of neonatal brachial plexus when subjected to stretch

Neonatal brachial plexus palsy (NBPP) results from over-stretching of the neonatal brachial plexus during complicated birthing scenarios. The lack of information on the biomechanical response of the neonatal brachial plexus complex when subjected to stretch limits our understanding of the NBPP injury mechanism. This study aims to fill that critical gap by using a neonatal piglet animal model and providing the in vivo biomechanical properties of the neonatal brachial plexus complex when subjected to stretch. Forty-seven brachial plexus levels (identified by the four brachial plexus terminal nerve branches namely musculocutaneous, median, ulnar, and radial), obtained from 16 neonatal Yorkshire piglets (3-5 days old), were subjected to stretch-induced failure. The average maximum load and corresponding strain were reported to be 16.6 ± 1.3 N and 36.1 ± 1.6%, respectively. Maximum loads reported at the musculocutaneous level were significantly lower than the median and radial levels. No differences in strains at failure were reported at all four tested levels. Proximal or distal failure locations were reported in 83% of the tests with 17% mid-length ruptures that were primarily reported at the bifurcation of the median and ulnar brachial plexus levels. Histological studies reported an overall loss of wavy pattern of the nerve fibers, an increase in nerve spacing, fiber disruptions, and blood vessel ruptures in the stretched tissue. This in vivo piglet animal study offers insight into the NBPP mechanism by reporting biomechanical, injury location, and structural damage responses in neonatal brachial plexus when subjected to stretch.

A Giant Lipoma in the Distal Forearm of a Cadaver

OBJECTIVE

Lipomas are very common tumors which usually prefer the upper limbs and, depending on their size, may cause nerve compression, or may be asymptomatic. The current cadaveric report describes a giant lipoma in the distal forearm area.

CASE REPORT

A large mass (5.1 × 3.2 × 1.6 cm) was identified on the palmar surface of the distal forearm, during dissection of a 63-year-old male cadaver. The mass caused anteromedial displacement and flattening of the median nerve (MN). Despite the lack of information about the subject's medical history, MN compression was assumed on the basis of the lipoma's size, its vicinity to neural structures, and the MN displacement and flattening.

CONCLUSION

The enlarged distal forearm lipoma, located adjacent to the carpal tunnel, displaced and flattened the MN. The cadaveric finding described is clinically relevant for both differential diagnosis and surgical treatment of carpal tunnel syndrome.

Recent advances in neuroanatomy: the myotome update

The myotome of a muscle is the basis for diagnosing spinal and peripheral nerve disorders. Despite its critical importance in clinical neurology, myotome charts presented in many textbooks, surprisingly, show non-negligible discordances with each other. Many authors do not even clearly state the bases of their charts. Studies that have presented with raw data regarding myotome identification are rather rare. A classic study in the 19th century that pursued the nerve course in cadavers still has a substantial influence on existing charts, despite its definite limitations. Other scarce studies in humans include identification by root stimulation during surgery, clinical observations in root avulsion or spinal cord injury and clinical and electromyographical investigations in patients with single radiculopathies or certain plexopathies. A few recent studies have proposed new theories regarding the myotomes of some muscles. T1 innervation of the median intrinsic hand muscles is a typical example. We have added a number of new findings, such as T1 innervation of the forearm flexor muscles innervated by the median nerve except the pronator teres and flexor carpi radialis, C5 innervation of the brachioradialis, and two C6 indicator muscles, pronator teres and extensor carpi radialis brevis. Increased accuracy of the myotome charts will improve the localisation in neurology.

Non-invasive central nervous system assessment of a porcine model of neuropathic pain demonstrates increased latency of somatosensory-evoked potentials

BACKGROUND

The study of chronic pain and its treatments requires a robust animal model with objective and quantifiable metrics. Porcine neuropathic pain models have been assessed with peripheral pain recordings and behavioral responses, but thus far central nervous system electrophysiology has not been investigated. This work aimed to record non-invasive, somatosensory-evoked potentials (SEPs) via electroencephalography in order to quantitatively assess chronic neuropathic pain induced in a porcine model.

NEW METHOD

Peripheral neuritis trauma (PNT) was induced unilaterally in the common peroneal nerve of domestic farm pigs, with the contralateral leg serving as the control for each animal. SEPs were generated by stimulation of the peripheral nerves distal to the PNT and were recorded non-invasively using transcranial electroencephalography (EEG). The P30 wave of the SEP was analyzed for latency changes.

RESULTS

P30 SEPs were successfully recorded with non-invasive EEG. PNT resulted in significantly longer P30 SEP latencies (p < 0.01 [n = 8]) with a median latency increase of 14.3 [IQR 5.0 - 17.5] ms. Histological results confirmed perineural inflammatory response and nerve damage around the PNT nerves.

COMPARISON WITH EXISTING METHOD(S)

Control P30 SEPs were similar in latency and amplitude to those previously recorded invasively in healthy pigs. Non-invasive recordings have numerous advantages over invasive measures.

CONCLUSIONS

P30 SEP latency can serve as a quantifiable neurological measure that reflects central nervous system processing in a porcine model of chronic pain. Advancing the development of a porcine chronic pain model will facilitate the translation of experimental therapies into human clinical trials.

Evaluation of motor and sensory neuron populations in a mouse median nerve injury model

BACKGROUND

Peripheral nerves can regenerate and restore function after injury but this process is hindered by many factors including chronic denervation, motor end-plate resorption and Schwann cell senescence. Forelimb injury models in rodents are becoming increasingly popular as they more accurately reflect the physiology and biomechanics of upper extremity nerve injuries. However several aspects of this surgical model remain poorly characterized.

NEW METHOD

C57Bl/6 mice underwent enumeration of median nerve motor and sensory neuron pools using retrograde labeling with or without nerve transection. Distal histomorphometry of uninjured mouse median nerves was also examined. Baseline reference values of volitional forelimb grip strength measurements were determined and the rate of neural elongation was also estimated.

RESULTS

We identified 1363 ± 165 sensory and 216 ± 16 motor neurons within the uninjured dorsal root ganglia (DRG) and ventral spinal cord, respectively. Eight days following injury, approximately 34% of motoneurons had elongated a distance of 5 mm beyond the repair site 8 days following injury. Volitional grip strength decreased 50% with unilateral median nerve transection and was negligible with contralateral flexor tendon tenotomy.

COMPARISON WITH EXISTING METHOD

Our spinal cord and DRG harvesting technique presented here was technically straightforward and reliable. Estimates of motor and sensory neuron numbers for the mouse median nerve compared favourably with studies using intramuscular injection of retrograde neurotracer. Histomorphometry data was consistent with and reinforced reference values in the literature.

CONCLUSIONS

This study provides data that further develops an increasingly popular surgical model for studying peripheral nerve injury and repair.

Pearls & Oy-sters: Case of Atypical Peripheral Nerve Findings Following Paclitaxel for Breast Cancer

Neuromuscular ultrasound (NMUS) is a valuable tool in establishing a diagnosis of carpal tunnel syndrome (CTS) and can be particularly helpful in patients with clinical CTS but normal nerve conduction studies (NCSs). This case involves the uncommon presentation of enlarged median nerves on NMUS with normal NCS in a patient with breast cancer who developed chemotherapy-induced peripheral neuropathy and CTS after taxane treatment. This case demonstrates that CTS should not be excluded based on electrodiagnostic studies alone, and comorbid CTS should be considered in patients receiving neurotoxic chemotherapy, even in the setting of normal NCS.

Sonographic peripheral nerve cross-sectional area in adults, excluding median and ulnar nerves: A systematic review and meta-analysis

INTRODUCTION/AIMS

Although electromyography remains the "gold standard" for assessing and diagnosing peripheral nerve disorders, ultrasound has emerged as a useful adjunct, providing valuable anatomic information. The objective of this study was to conduct a systematic review and meta-analysis evaluating the normative sonographic values for adult peripheral nerve cross-sectional area (CSA).

METHODS

Medline and Cochrane Library databases were systematically searched for healthy adult peripheral nerve CSA, excluding the median and ulnar nerves. Data were meta-analyzed, using a random-effects model, to calculate the mean nerve CSA and its 95% confidence interval (CI) for each nerve at a specific anatomical location (= group).

RESULTS

Thirty groups were identified and meta-analyzed, which comprised 16 from the upper extremity and 15 from the lower extremity. The tibial nerve (n = 2916 nerves) was reported most commonly, followed by the common fibular nerve (n = 2580 nerves) and the radial nerve (n = 2326 nerves). Means and 95% confidence interval (CIs) of nerve CSA for the largest number of combined nerves were: radial nerve assessed at the spiral groove (n = 1810; mean, 5.14 mm2 ; 95% CI, 4.33 to 5.96); common fibular nerve assessed at the fibular head (n = 1460; mean, 10.18 mm2 ; 95% CI, 8.91 to 11.45); and common fibular nerve assessed at the popliteal fossa (n = 1120; mean, 12.90 mm2 ; 95% CI, 9.12 to 16.68). Publication bias was suspected, but its influence on the results was minimal.

DISCUSSION

Two hundred thirty mean CSAs from 15 857 adult nerves are included in the meta-analysis. These are further categorized into 30 groups, based on anatomical location, providing a comprehensive reference for the clinician and researcher investigating adult peripheral nerve anatomy.

Electrodiagnostic Testing for Carpal Tunnel Syndrome When Routine Median Sensory and Thenar Motor Responses Are Absent

PURPOSE

The cardinal symptoms of carpal tunnel syndrome (CTS) include pain in the affected hand(s). The median/second lumbrical nerve (Med2ndL) seems relatively preserved in severe CTS, with previous small studies suggesting its value in electromyogram to localize a median neuropathy to the wrist when both initial routine sensory and thenar motor responses are absent.

METHODS

This is a retrospective analysis of 208 hands in 183 patients with electrophysiologically markedly severe CTS (absent routine sensory and thenar motor median responses) who underwent stimulation of both the Med2ndL and ulnar/second dorsal interosseous (Uln2ndDIn) motor nerves. A Med2ndL distal latency of ≥ 0.5 milliseconds when compared with the Uln2ndDIn supported the diagnosis of CTS. The presence or absence of hand pain was recorded if these data were available.

RESULTS

Some 83.7% of hands (172/208) in 183 patients with markedly severe CTS had preservation of the Med2ndL meeting criteria for CTS. In those with pain data available, 77.1% (81/105) of hands had no pain. Of those 105 hands, 87 had preservation of the Med2ndL with 79.3% (69/87) demonstrating no pain.

CONCLUSIONS

This is a large study that demonstrates the relative preservation of the Med2ndL response in markedly severe CTS. Assessment of the Med2ndL should be considered to electrophysiologically support CTS when routine sensory and thenar motor responses are absent. In addition, most patients with electrophysiologically markedly severe CTS had no pain.

[A Rare Cause for Median Nerve Irritation]

INTRODUCTION

A lesion of the median nerve due to nerve compression comparable to carpal tunnel syndrome is very common, with an incidence of 3.3 to 3.45 cases per 1000 inhabitants and year. In the present case series, we report compressions of the -median nerve due to wearing a smartwatch, which to our knowledge has not been previously reported in the literature. We -describe five patients with typical carpal tunnel symptoms and pathological sensory neurography who had been wearing a smartwatch more than 24 hours/day for several weeks to detect atrial fibrillation, and whose symptoms and electrophysiology improved after they stopped wearing it. Smartwatches can be an interesting additional gadget for diagnosing diseases such as cardiac arrhythmias. However, the tight wearing that is necessary can possibly also compress the median nerve and lead to symptoms such as the carpal tunnel syndrome. According to the manufacturer, it is important to choose the right strap size when buying and only leave the watch very tight when you need the sensors (but without feeling uncomfortable) and otherwise to tie the strap loosely, to take it off or alternate the wrist in order to avoid pain and injury.

Directional recordings of somatosensory evoked potentials from the sensory thalamus in chronic poststroke pain patients

OBJECTIVE

The aim of this feasibility study was to investigate the properties of median nerve somatosensory evoked potential (SEPs) recorded from segmented Deep Brain Stimulation (DBS) leads in the sensory thalamus (VP) and how they relate to clinical and anatomical findings.

METHODS

We analyzed four patients with central post-stroke pain and DBS electrodes placed in the VP. Median nerve SEPs were recorded with referential and bipolar montages. Electrode positions were correlated with thalamus anatomy and tractography-based medial lemniscus. Early postoperative clinical paresthesia mapping was performed by an independent pain nurse. Finally, we performed frequency and time-frequency analyses of the signals.

RESULTS

We observed differences of SEP amplitudes recorded along different directions in the VP. SEP amplitudes did not clearly correlate to both atlas-based anatomical position and fiber-tracking results of the medial lemniscus. However, the contacts of highest SEP amplitude correlated with the contacts of lowest effect-threshold to induce paraesthesia.

CONCLUSIONS

SEP recordings from directional DBS leads offer additional information about the neurophysiological (re)organization of the sensory thalamus.

SIGNIFICANCE

Directional recordings of thalamic SEPs bear the potential to assist clinical decision-making in DBS for pain.

Device to relate the superficial temperature of the forearm and the muscular conditioning of the flexor muscle for prevention of carpal tunnel syndrome in E-sports

Currently, various labor and competitive sectors use computing devices as the primary development tool, one of them being e-sports or electronic sports. Constant use of the computer involves repetitive use of the fingers' superficial and deep flexor muscles, which causes the median nerve to squeeze and irritate in the carpal tunnel space causing carpal tunnel syndrome (CTS). There are methods that can minimize stress on the hands and wrists through muscle conditioning. However, there are no quantifiable indicators of the conditioning performed. Therefore, this work aims to develop a device capable of conditioning the flexor muscles and indicate in a quantifiable way the conditioning carried out as prevention of carpal tunnel syndrome. After the analysis of these data, a direct relationship between the surface temperature of the forearm and the muscular conditioning of the flexors is observed. The temperature variation during conditioning is greatest in the distal forearm with a range of [32.76-34.38]°. Post-conditioning temperature retention is greater in the distal forearm over time.

SARS-COV-2 INFECTION AND INVOLVEMENT OF PERIPHERAL NERVOUS SYSTEM: A CASE SERIES OF CARPAL TUNNEL SYNDROME AGGRAVATION OR NEW ONSET WITH COVID-19 DISEASE AND A REVIEW OF LITERATURE

COVID-19 may be asymptomatic or have a typical presentation with fever, cough, anosmia, lymphocytopenia. In some cases, it occurs with a "chimeric" presentation, with more subtle and ambiguous symptoms which may be initially misdiagnosed and are referred to in long covid condition. A possible central and peripheral nervous system involvement has been recognized. We present our experience and review the literature about association between carpal tunnel syndrome (CTS) and hand's arthritis presenting a case series of patients who firmly state that their condition of CTS arised or got worse during a typical presentation of COVID-19. The outbreak of COVID-19 has resulted in significant global healthcare implications. While the respiratory manifestations of COVID-19 have been widely studied, there is emerging evidence suggesting potential associations between COVID-19 and various other health conditions. This review of the literature aims to investigate the potential relationship between COVID-19 and the development or exacerbation of CTS. By synthesizing the available literature on this topic, we aim to provide a comprehensive overview of the current knowledge and enhance our understanding of the potential implications of COVID-19 on CTS. Case series: In this article we report 13 cases of typical presentations of COVID-19 with fever, myalgia, and respiratory system involvement, with a simultaneous aggravation of the median nerve pre-existing neuralgia and some cases that developed a median nerve neuralgia during COVID-19, which came to the attention of the hand surgeon. Some cases had stable symptomatic CTS and were on waiting list for surgical carpal tunnel release, some cases were previously asymptomatic and developed a median nerve neuralgia during COVID-19. All patients referred to a rapid worsening of acral paraesthesia and neuralgic pain of the same quality of CTS and in the median nerve topography. Some patients developed typical COVID-19 symptoms and died; the others were surgically treated. CTS could be an atypical presentations of COVID-19 or a condition of long-covid disease and clinical and epidemiological significance needs to be fully studied. We presented cases of worsening of the median nerve neuralgia which presented among other symptoms of COVID infection. We conclude a causal relation may exist and needs to be further investigated.