Clinical Neurophysiology Practice最新文献

Objective

This study aimed to investigate the potential of whole-forearm flexor muscle (WFFM) compound muscle action potential (CMAP) as a quantitative biomarker for inclusion body myositis (IBM) pathology.

Methods

We prospectively enrolled 14 consecutive patients (10 men and 4 women) diagnosed with IBM based on muscle biopsies. We evaluated the baseline-to-peak amplitude of the WFFM CMAP and other quantitative parameters, including grip and pinch strength, Inclusion Body Myositis Functional Rating Scale (IBMFRS) score, and other routine muscle CMAP amplitudes.

Results

The WFFM CMAP was strongly correlated with disease duration and the IBMFRS score. The WFFM CMAP on the more affected side was lower than that on the less affected side. Furthermore, grip power was strongly correlated with the WFFM CMAP, whereas lateral pinch strength was strongly correlated with the WFFM and first dorsal interosseous CMAPs. The 3-point pinch strength was also correlated with the WFFM CMAP.

Conclusions

This study demonstrates that the WFFM CMAP may serve as a biomarker of severity in IBM.

Significance

Identification of this biomarker can support drug development, diagnosis, prognosis, and treatment options for patients with IBM.

Objective: H-reflex recordings of the relaxed flexor carpi ulnaris (FCU) muscle are not frequently performed in clinical or laboratory settings. There are no normative values or reliability standards. This is most likely because of technical difficulties associated with this technique. This study performed surface recordings of the H-reflex of relaxed FCU muscles to establish the normative values and the reliability of these recordings. Methods: The maximum amplitude and latency of the FCU H-reflex were recorded bilaterally in 53 healthy young adults. Normative values and interclass correlation coefficients (ICCs) were calculated. Results: The amplitude of the relaxed FCU H-reflex were recorded in nearly all participants (96 %). The FCU H-reflex average maximum amplitude was 1.35 mV. The average latency was 18.8 ms. H-reflex amplitude and latency were not statistically different among gender or limb sides. Amplitude and latency were recoded reliably both within and between sessions with ICCs ranging from 0.96 to 0.99. Conclusions: Recordings of the relaxed FCU H-reflex were readily available and could be assessed reliably within and between sessions. Significance: This method might be used more frequently in clinical and laboratory settings to examine C7 and C8 spinal segments and upper limb muscle normal function or neuromuscular pathology.

Introduction

Pathogenic variants of the MTOR gene result in the Smith-Kingsmore syndrome, whose phenotypical spectrum includes facial dysmorphisms and neurological features. Expressivity is variable, patients exhibit a combination of intellectual disability, macrocephaly and epilepsy. The diagnosis can be missed, failing to detect the causative pathogenic mutation in patients with somatic mosaicism or even skipping to analyze MTOR when the phenotype is not completely expressed.

Case study

Herein, we report two children harboring the same MTOR recurring mutation (c.5395G>A/p.Glu1799Lys) whose EEG displayed a peculiar combination of midline rhythmic waveforms and asynchronous spike-and-wave discharges with anterior fast activity in sleep and wake. Conclusion: We suggest these features might be considered as possible hallmarks of the syndrome and could aid to expedite the diagnosis when the phenotype is incomplete.

Objective

To establish if induced current direction across the motor cortex alters the sensitivity of transcranial magnetic stimulation (TMS)-evoked short-interval intracortical inhibition (SICI) as an ALS biomarker.

Methods

Threshold tracking-TMS was undertaken in 35 people with ALS and 39 controls. Using a coil orientation which induces posterior-anterior (PA)-directed current across the motor cortex, SICI (1 ms and 3 ms interstimulus intervals) and intracortical facilitation (ICF, 10 ms interstimulus interval) were recorded. SICI_3ms was also recorded using a coil orientation which induces anterior-posterior (AP)-directed current across the motor cortex.

Results

At group level, SICI_3ms-PA (AUROC = 0.7), SICI_3ms-AP (AUROC = 0.8) and SICI_1ms (AUROC = 0.66) were substantially lower in those with ALS, although there was considerable interindividual heterogeneity. Averaging across interstimulus intervals (ISIs) marginally improved SICI_PA sensitivity (AUROC = 0.76). Averaging SICI values across ISIs and orientations into a single SICI measure did not substantially improve sensitivity (AUROC = 0.81) compared to SICI_3ms-AP alone. SICI_3ms-AP and SICI_3ms-PA did not significantly correlate (rho = 0.19, p = 0.313), while SICI_1ms-PA and SICI_3ms-PA did (rho = 0.37, p = 0.006). Further, those with ALS with the lowest SICI_3ms-PA were not those with the lowest SICI_3ms-AP. ICF was similar between groups (AUROC = 0.50).

Conclusions

SICI_PA and SICI_AP are uncorrelated measures of motor cortical inhibitory functions which are useful as distinct, unequally affected, measures of disinhibition in ALS.

Significance

Examining both SICI_PA and SICI_AP may facilitate more comprehensive characterisation of motor cortical disinhibition in ALS.

Objective

Many artificial intelligence approaches to muscle ultrasound image analysis have not been implemented on usable devices in clinical neuromuscular medicine practice, owing to high computational demands and lack of standardised testing protocols. This study evaluated the feasibility of using real-time texture analysis to differentiate between various pathological conditions.

Methods

We analysed 17,021 cross-sectional ultrasound images of the biceps brachii of 75 participants, including 25 each with neurogenic disorders, myogenic disorders, and healthy controls. The size and location of the regions of interest were randomly selected to minimise bias. A random forest classifier utilising texture features such as Dissimilarity and Homogeneity was developed and deployed on a mobile PC, enabling real-time analysis.

Results

The classifier distinguished patients with an accuracy of 81 %. Echogenicity and Contrast from the Co-Occurrence Matrix were significant predictive features. Validation on 15 patients achieved accuracies of 78 %/93 % per image/patient over 15-second videos, respectively. The use of a mobile PC facilitated real-time estimation of the underlying pathology during ultrasound examination, without influencing procedures.

Conclusions

Real-time automatic texture analysis is feasible as an adjunct for the diagnosis of neuromuscular disorders.

Significance

Artificial intelligence using texture analysis with a light computational load supports the semi-quantitative evaluation of neuromuscular ultrasound.

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder of the human motor system, first described in the 19th Century. The etiology of ALS appears to be multifactorial, with a complex interaction of genetic, epigenetic, and environmental factors underlying the onset of disease. Importantly, there are no known naturally occurring animal models, and transgenic mouse models fail to faithfully reproduce ALS as it manifests in patients. Debate as to the site of onset of ALS remain, with three competing theories proposed, including (i) the dying-forward hypothesis, whereby motor neuron degeneration is mediated by hyperexcitable corticomotoneurons via an anterograde transsynaptic excitotoxic mechanism, (ii) dying-back hypothesis, proposing the ALS begins in the peripheral nervous system with a toxic factor(s) retrogradely transported into the central nervous system and mediating upper motor neuron dysfunction, and (iii) independent hypothesis, suggesting that upper and lower motor neuron degenerated independently. Transcranial magnetic stimulation studies, along with pathological and genetic findings have supported the dying forward hypothesis theory, although the science is yet to be settled. The review provides a historical overview of ALS, discusses phenotypes and likely pathogenic mechanisms.

Objective

Standard nerve excitability testing (NET) predominantly assesses Aα- and Aβ-fiber function, but a method examining small afferents would be of great interest in pain studies. Here, we examined the properties of a novel perception threshold tracking (PTT) method that preferentially activates Aδ-fibers using weak currents delivered by a novel multipin electrode and compared its reliability with NET.

Methods

Eighteen healthy subjects (mean age:34.06 ± 2.0) were examined three times with motor and sensory NET and PTT in morning and afternoon sessions on the same day (intra-day reliability) and after a week (inter-day reliability). NET was performed on the median nerve, while PTT stimuli were delivered through a multipin electrode located on the forearm. During PTT, subjects indicated stimulus perception via a button press and the intensity of the current was automatically increased or decreased accordingly by Qtrac software. This allowed changes in the perception threshold to be tracked during strength-duration time constant (SDTC) and threshold electrotonus protocols.

Results

The coefficient of variation (CoV) and interclass coefficient of variation (ICC) showed good–excellent reliability for most NET parameters. PTT showed poor reliability for both SDTC and threshold electrotonus parameters. There was a significant correlation between large (sensory NET) and small (PTT) fiber SDTC when all sessions were pooled (r = 0.29, p = 0.03).

Conclusions

Threshold tracking technique can be applied directly to small fibers via a psychophysical readout, but with the current technique, the reliability is poor.

Significance

Further studies are needed to examine whether Aβ-fiber SDTC may be a surrogate biomarker for peripheral nociceptive signalling.

Aesthetic use of low doses of Botulinum toxin (BoNT) injections into the facial muscles has become a leading non-surgical aesthetic treatment worldwide to reduce facial wrinkles, including glabellar lines, forehead lines, and periorbital wrinkles. Within these aesthetic applications, BoNT injections intend to reduce and prevent wrinkles, and the recommended usage of 2 years is often exceeded, which may result in atrophy of the injected muscles. The long-term effects of BoNT injections in the facial muscles and the evidence of diffusion of BoNT to surrounding muscles are obvious pitfalls and challenges for clinical neurophysiologists in differential diagnosing neuromuscular transmission failures. Also, this is further complicated by the risk of developing side effects upon permanent chemical denervation of facial muscles, with less possibility for reinnervation.

This review summarizes the known long-term effects of BoNT over time in different facial muscles and the use of objective electrophysiological measures to evaluate these. A better understanding of the long-term effects of BoNT is essential to avoid misdiagnosing other neuromuscular disorders.

Introduction

The coil handle orientation plays a pivotal role in the therapeutic efficacy of repetitive transcranial magnetic stimulation (rTMS). However, there is currently no consensus on the optimal individualized coil handle orientation, especially for non-motor areas.

Case presentation

The present case reported a short-term effect of functional connectivity (FC)-guided rTMS with coil handle posterior-anterior 45° (PA45°) and posterior-anterior 135° (PA135°) on a patient with insomnia. Notably, in this case, the PA45° orientation was nearly perpendicular to the adjacent sulcus, while the PA135° orientation was almost parallel to it. Local brain activity and functional connectivity were assessed using resting-state functional magnetic resonance imaging (RS-fMRI). Additionally, motor evoked potentials (MEPs) were captured both pre and post-rTMS sessions.

Findings

The coil handle orientation PA45° outperformed the PA135° in both RS-fMRI and MEP outcomes. Moreover, a 9-day rTMS treatment led to discernible improvements in symptoms of depression and anxiety, complemented by a modest enhancement in sleep quality.