Motor Evoked Potentials Latency Research Articles

Study of the cortico-anorectal neurophysiology in women with fecal incontinence.

Fecal incontinence (FI) is a prevalent condition that disproportionately impacts women. Although sphincter biomechanics are well studied, the integrity of the cortico-anal motor pathway remains elusive. We evaluated the cortico-spino-anorectal pathway in women with FI against age-matched (AM-HV) and young healthy (Y-HV) volunteers. Observational study with 18 women with FI (mean age: 63.4±11.1), 15 AM-HV (60.7±9.01, and 15 Y-HV (24.2±5.39), conducted in a tertiary hospital. Participants underwent clinical evaluation, high-resolution anorectal manometry (HRAM), endoanal ultrasound, and transcranial/translumbosacral magnetic stimulation to assess anorectal motor evoked potentials (MEP). Clinical severity was measured with St. Mark's score, and quality of life with FIQL and EQ5D. Patients had longer MEP latencies than AM-HV in the cortico-anal (25.93±3.67 ms vs 22.89±1.38 ms) andright lumbo-rectal segments (5.64±1.35 ms vs4.39±1.27 ms; p<0.05) but not in the tibial segment (control)(33.35±2.88 ms vs 32.08±2.05 ms; p>0.05). However, tibial latencies were longer in AM-HV compared to Y-HV (32.08±2.05 ms vs 29.21±2.75 ms; p=0.003). In FI, 41.1% had cortico-anorectal impairments, 50% lumbo-anal, and 44.4% sacral. Overall, 82.4% showed delayed latencies in at least one of the 12 segments. HRAM revealed 83.24% had external anal sphincter (EAS) dysfunction, 40% internal sphincter dysfunction, and 23.57% both. MEP latencies inversely correlated with EAS squeeze strength. FI patients had significantly poorer EQ5D scores compared to both control groups. Women with FI show significant neuropathy in the cortico-spino-anorectal pathway linked to impaired anorectal function. These findings underscore the brain-gut axis's role in FI pathophysiology, advocating for advanced neurophysiological diagnostics and targeted interventions.

The Unchanging Latency of Transcranial Motor-Evoked Potentials Among Various Age Groups.

Background Human growth and development involve significant changes in bodily dimensions, yet motor learning appears to remain stable throughout life. This study investigates whether adjustments in motor velocity take place as individuals age by examining the latency of transcranial motor-evoked potentials (TcMEPs) across different age groups. Methods Data were collected from 100 patients who underwent surgery with intraoperative neuromonitoring at the All India Institute of Medical Sciences, New Delhi, between January 1, 2019, and January 1, 2020. TcMEP recordings were analyzed for 7 commonly monitored muscles across 7 distinct age groups: under 10 years, 10-19 years, 20-29 years, 30-39 years, 40-49 years, 50-59 years, and over 60 years. Results The analysis revealed no significant differences in motor-evoked potential (MEP) latency across the age groups, indicating that motor response latency remains stable despite the physical changes that occur with aging. Conclusion These findings enhance our understanding of motor learning, suggesting that motor response latency does not necessitate changes with age, highlighting the consistency of motor function over the human lifespan.

Promotion of nerve regeneration and motor function recovery in SCI rats using LOCAS-iPSCs-NSCs

BackgroundSpinal cord injury (SCI) is a severe traumatic spinal condition with a poor prognosis. In this study, a scaffold called linearly ordered collagen aggregates (LOCAS) was created and loaded with induced pluripotent stem cells (iPSCs)-derived neural stem cells (NSCs) from human umbilical cord blood derived mesenchymal stem cells (hUCB-MSCs) to treat SCI in a rat model.MethodsThe rats underwent a complete transection SCI resulting in a 3-mm break at either the T9 or T10 level of the spinal cord.ResultsScanning electron microscope analysis revealed a uniform pore structure on the coronal plane of the scaffold. The LOCAS had a porosity of 88.52% and a water absorption of 1161.67%. Its compressive modulus and stress were measured at 4.1 MPa and 205 kPa, respectively, with a degradation time of 10 weeks. After 12 weeks, rats in the LOCAS-iPSCs-NSCs group exhibited significantly higher BBB scores (8.6) compared to the LOCAS-iPSCs-NSCs group (5.6) and the Model group (4.2). The CatWalk analysis showed improved motion trajectory, regularity index (RI), and swing speed in the LOCAS-iPSCs-NSCs group compared to the other groups. Motor evoked potentials latency was lower and amplitude was higher in the LOCAS-iPSCs-NSCs group, indicating better neural function recovery. Histological analysis demonstrated enhanced neuronal differentiation of NSCs and nerve fiber regeneration promoted by LOCAS-iPSCs-NSCs, leading to improved motor function recovery in rats. The LOCAS scaffold facilitated ordered neurofilament extension and guided nerve regeneration.ConclusionsThe combination of LOCAS and iPSCs-NSCs demonstrated a positive therapeutic impact on motor function recovery and tissue repair in rats with SCI. This development offers a more resilient bionic microenvironment and presents novel possibilities for clinical SCI repair.

Effects of VR task-oriented training combined with rTMS on balance function and brain plasticity in stroke patients: a randomized controlled trial study protocol

BackgroundBalance dysfunction affects 70% of stroke patients. Emerging neurophysiological approaches, such as virtual reality therapy (VRT) and repetitive transcranial magnetic stimulation (rTMS), have been proven by clinical studies that the balance function of stroke patients can be improved when applied alone, but there are relatively few studies on the combined treatment of balance dysfunction after stroke. This study aimed to evaluate the impact of a 4-week intensive intervention combining VRT and rTMS on both balance function and brain plasticity among stroke patients.MethodsThis single-blind, randomized controlled trial was conducted at the Rehabilitation Medical Center of the Rehabilitation General Hospital of Ningxia Medical University. A cohort of 136 stroke patients, with durations of 2 to 24 weeks post-stroke, were enrolled in the study. Participants were randomly allocated in a 1:1:1:1 ratio to four groups: the VR group (n = 34), the rTMS group (n = 34), the combined treatment group receiving both VR and rTMS (n = 34), and the control group undergoing traditional balance training (n = 34). All patients underwent a standardized inpatient rehabilitation program over 4 weeks. The VR group received daily 30-min sessions of VR therapy for 20 days. The rTMS group underwent daily sessions of rTMS stimulation for 20 min, targeting the motor imagery region in the affected hemisphere. The combination group received VR therapy after completing their rTMS treatment. The control group received conventional balance training, with each session lasting 30 min. Additionally, all patients received an extra 60 min of standard rehabilitation therapy twice daily. Assessments were conducted at baseline, 2 weeks, and 4 weeks post-treatment, using the Berg Balance Scale (BBS) as the primary measure, and secondary measures including the Timed Up-and-Go Test (TUGT), Fugl-Meyer Assessment-Lower Extremity (FMA-LE), and 6-m walking test (6MWT), as well as assessments for brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VGEF), tyrosine receptor kinase (TrκB), motor-evoked potential latency (PL), central motor conduction time (CMCT), and amplitude.DiscussionThe widespread application of VR technology and rTMS in clinical settings is well-established. However, the potential synergistic effects of combining these modalities on balance function and neuroplasticity in stroke patients remain uncertain. Our hypothesis suggests that the integration of VR with rTMS may result in more pronounced improvements in both balance function and neuroplasticity among stroke patients, surpassing the outcomes achievable with VR alone, rTMS alone, or traditional therapy. The possible mechanism is that VR-based training combined with rTMS plays a superimposed effect, promoting better repair of damaged neurons and ultimately improving balance function in stroke patients. The positive results anticipated from this trial could provide objective evidence advocating for the concurrent use of VR and rTMS in clinical interventions.Trial registrationThe study protocol underwent review and approval by the Medical Research Ethics Committee of the General Hospital of Ningxia Medical University on January 26, 2024 (No. KYLL-2024–0162). Subsequently, it was registered in the Chinese Clinical Trial Registry on March 11, 2024 (registration number: ChiCTR2400081775). Currently, the study is still ongoing.

Imagining Speeds up the Effect of Motor Imagery on Central Motor Conduction Time.

Although motor imagery (MI) has been reported to increase motor cortical excitability, its effect on central motor conduction time (CMCT), a widely used neurophysiological diagnostic method, has not been investigated. In this study, we sought to determine the effect of MI on CMCT. In this cross-sectional study, 21 healthy volunteers (11 females, 10 males) aged 24 to 67 years (mean age: 38.8 years) were recruited between April 2022 and June 2023.CMCT was calculated during MI from the abductor digiti minimi (ADM) and tibialis anterior (TA) muscles. Measurements were also performed with conventional measurement methods, such as resting and voluntary contraction, to compare the effect of MI on CMCT. The ANOVAtest revealed that the CMCT session (rest, MI, and voluntary contraction) was a significant factor (p < 0.05). In both muscles, CMCT was shorter in the imagery state than in the resting state but longer than in the voluntary contraction state (p < 0.05). Similarly, motor-evoked potential (MEP) latencies obtained during imagery were shorter for both muscles than the resting state but longer for the voluntary contraction state. The study's findings suggest that MI is a mental activity that modulates CMCT measurement.MI shows a voluntary contraction-like effect on CMCT and MEP latency, although the effect is more uncertain.

The corticospinal tract in multiple sclerosis: correlation between cortical excitability and magnetic resonance imaging measures

Multiple sclerosis (MS) is a central nervous system disease involving gray and white matters. Transcranial magnetic stimulation (TMS) and magnetic resonance imaging (MRI) could help identify potential markers of disease evolution, disability, and treatment response. This work evaluates the relationship between intracortical inhibition and facilitation, motor cortex lesions, and corticospinal tract (CST) integrity. Consecutive adult patients with progressive MS were included. Sociodemographic and clinical data were collected. MRI was acquired to assess primary motor cortex lesions (double inversion and phase-sensitive inversion recovery) and CST integrity (diffusion tensor imaging). TMS outcomes were obtained: motor evoked potentials (MEP) latency, resting motor threshold, short-interval intracortical facilitation (ICF) and inhibition. Correlation analysis was performed. Twenty-five patients completed the study (13 females, age: 55.60 ± 11.49 years, Expanded Disability Status Score: 6.00 ± 1.25). Inverse correlations were found between ICF mean and each of CST radial diffusivity (RD) (ρ =-0.56; p < 0.01), CST apparent diffusion coefficient (ADC) (ρ=-0.44; p = 0.03), and disease duration (ρ=-0.46; p = 0.02). MEP latencies were directly correlated with disability scores (ρ = 0.55; p < 0.01). High ADC/RD and low ICF have been previously reported in patients with MS. While the former could reflect structural damage of the CST, the latter could hint towards an aberrant synaptic transmission as well as a depletion of facilitatory compensatory mechanisms that helps overcoming functional decline. The findings suggest concomitant structural and functional abnormalities at later disease stages that would be accompanied with a heightened disability. The results should be interpreted with caution mainly because of the small sample size that precludes further comparisons (e.g., treated vs. untreated patients, primary vs. secondary progressive MS). The role of these outcomes as potential MS biomarkers merit to be further explored.

Modulation of motor cortex inhibition during manual dexterity tasks: an adaptive threshold hunting study.

Background: The ability to perform intricate movements is crucial for human motor function. The neural mechanisms underlying precision and power grips are incompletely understood. Corticospinal output from M1 is thought to be modulated by GABAA-ergic intracortical networks within M1. Objectives: To investigate the contribution of M1 intracortical inhibition to fine motor control using adaptive threshold hunting with paired-pulse TMS during pinching and grasping tasks. We hypothesised that SICI could be assessed during voluntary activation, and that corticomotor excitability and SICI modulation would be greater during pinch than grasp reflecting corticospinal control. Methods: Seventeen healthy participants performed gradual pinch and grasp tasks. Using an adaptive threshold-hunting method, paired-pulse TMS was applied in the anterior-posterior current direction to assess cortical excitability and SICI in the dominant FDI muscle. SICI and corticomotor excitability were analysed using an LMM. MEP latencies were obtained in LM, PA and AP current directions and compared using paired t-tests. Results: MEP latencies were prolonged with PA and AP coil orientations compared to LM, with AP showing the largest latency. During single-pulse TMS, there was no difference in the TMS intensity required to reach the MEP target during pinching and grasping. Greater inhibition was found during pinching compared to grasping. Conclusion: ATH with paired-pulse TMS permits investigation of intracortical inhibitory networks and their modulation during the performance of dexterous motor tasks revealing a greater modulation of GABAA-ergic inhibition contributing to SICI during pinching compared to grasping.

Fluctuations in resting motor threshold during electroconvulsive and magnetic seizure therapy

Objectives Magnetic seizure therapy (MST) is more benign than electroconvulsive therapy (ECT) in terms of cognitive impairment. However, whether these two ‘artificial seizures’ facilitate the central motor neural pathway and the motor cortical effects have not been investigated. The study aimed to compare the effects of ECT and MST on motor-evoked potential (MEP) in patients with mental disorders. Methods Forty-nine patients with mental disorders (major depressive disorder, bipolar disorder type II and schizophrenia [SCZ]) received 6 treatment sessions of vertex MST versus 6 bifrontal ECT treatments in a nonrandomized comparative clinical design. Data on the duration of motor seizures were collected for each treatment. MEP latency and the resting motor threshold (rMT) were measured at baseline and after every two treatments. Comparisons were performed between or within the groups. Results Seizure durations were significantly longer in the ECT group compared to the MST group across multiple sessions. Both MST and ECT demonstrated a significant reduction in rMT in the left and right hemispheres after the fourth (T3) and sixth treatments (T4) compared to baseline (T1). However, there were no significant changes in MEP latency within or between the groups throughout the treatment sessions. The only difference was that the rMT in the left cerebral hemisphere was significantly lower after T4 than after the second treatment (T2). There was no difference in rMT between the ECT and MST groups. Conclusions Both ECT and MST facilitate the central motor pathway, with a shared mechanism of increased motor cortex excitability.

Effect of Intermittent Theta Burst Stimulation Dual-Target Stimulation on Lower Limb Function in Patients with Incomplete Spinal Cord Injury: A Randomized, Single-Blind, Sham-Controlled Study

To explore the influence of intermittent theta burst stimulation (iTBS) dual-target stimulation on lower limb function in patients with incomplete spinal cord injury (iSCI). A randomized, single -blind, sham-controlled trial was used in this study. Thirty iSCI patients with lower limb dysfunction meeting the inclusion criteria were randomly divided into a sham group and an iTBS group, with 15 cases in each group. The iTBS group received conventional rehabilitation therapy combined with iTBS dual-target stimulation on the central cerebral sulcus and the nerve root of the spinal cord injury segment. The sham group was treated with conventional rehabilitation therapy combined with iTBS dual-target sham stimulation therapy. Comprehensive functional assessment was performed on all patients before treatment, on the day 3 and day 21 of treatment. The main evaluation indicators were as follows: amplitude and latency of motor-evoked potential (MEP) in the anterior tibial muscles of both lower limbs, latency of sensory-evoked potential (SEP) of both lower limbs, knee flexor strength and knee extensor strength, lower extremity motor score (LEMS), lower extremity sensory score, spinal cord independence measure (SCIM) score, and gait parameters (stride speed, stride frequency, stride length, and ground reaction force). On day 21 of treatment, in the iTBS group, the MEP amplitude of the anterior tibial muscles increased, the latency of MEP shortened, knee flexor strength and knee extensor strength increased, and the LEMS and SCIM score of both lower limbs increased. In addition, there were statistically significant differences in the muscle strength of the knee flexion muscle, knee extensor muscle, MEP amplitude, LEMS, and SCIM between the 2 groups (P < 0.05). Among the 10 patients who could walk with an assisted walker, the step length and step frequency of the iTBS group were increased compared with the sham group after treatment (P < 0.01), and the ground reaction force was increased (P < 0.05). There was no significant difference in the lower extremity sensory score of the lower limbs between the 2 groups (P>0.05). ITBS dual-target stimulation can significantly improve the motor function of both lower limbs in patients with iSCI but does not significantly improve the sensory function of both lower limbs. Therefore, this treatment mode may participate in the reconstruction and repair of some nerve circuits in patients with iSCI. In addition, iTBS dual-target stimulation can improve the ability of iSCI patients to perform daily living.

Transcranial magnetic stimulation in the assessment of acupuncture effect on exercise-induced fatigue.

Acupuncture as a traditional Chinese medicine therapy relies on unique theories to alleviate fatigue. The aim of this study is to evaluate the effect of acupuncture on exercise-induced fatigue utilizing transcranial magnetic stimulation (TMS). A total of 20 participants with regular exercise habits were recruited for this study. All participants were randomly assigned to receive either acupuncture or sham acupuncture intervention for exercise-induced fatigue. TMS and a heart rate monitor were used to measure the amplitude and latency of motor evoked potential (MEP) as well as heart rate every 5min over a 30-min period. The blood lactic acid (BLA) levels were measured using Lactate Scout+ at baseline, 0min, and 30min after fatigue. Two-way repeated measures analysis of variance was utilized to compare the differences between the effects of acupuncture method and time. Bonferroni post hoc tests were conducted to compare specific differences. Statistical significance was set at p<.05. Interaction effect was observed between acupuncture method and time effect in terms of amplitude (F(1, 38)=5.40, p<.001, η2=0.12) and latency (F(1, 38)=3.78, p=.008, η2=.09) of MEP. The application of acupuncture can promote the recovery of heart rate especially at 30min (p<.05), but which seem insufficient to generate significant difference in BLA (F(1, 38)=0.067, p=.797, η2=0.002). Acupuncture can promote the increase of MEP amplitude, shorten MEP latency, and restore heart rate. Preliminary findings provide novel insights for individuals with exercise habits to alleviate fatigue and enhance sports performance.

Motor function in multiple sclerosis assessed by navigated transcranial magnetic stimulation mapping.

Impaired motor function is a major cause of disability in multiple sclerosis (MS), involving various neuroplasticity processes typically assessed by neuroimaging. This study aimed to determine whether navigated transcranial magnetic stimulation (nTMS) could also provide biomarkers of motor cortex plasticity in patients with MS (pwMS). nTMS motor mapping was performed for hand and leg muscles bilaterally. nTMS variables included the amplitude and latency of motor evoked potentials (MEPs), corticospinal excitability measures, and the size of cortical motor maps (CMMs). Clinical assessment included disability (Expanded Disability Status Scale, EDSS), strength (MRC scale, pinch and grip), and dexterity (9-hole Pegboard Test). nTMS motor mapping was performed in 68 pwMS. PwMS with high disability (EDSS ≥ 3) had enlarged CMMs with less dense distribution of MEPs and various MEP parameter changes compared to pwMS with low disability (EDSS < 3). Patients with progressive MS had also various MEP parameter changes compared to pwMS with relapsing remitting form. MRC score correlated positively with MEP amplitude and negatively with MEP latency, pinch strength correlated negatively with CMM volume and dexterity with MEP latency. This is the first study to perform 4-limb cortical motor mapping in pwMS using a dedicated nTMS procedure. By quantifying the cortical surface representation of a given muscle and the variability of MEP within this representation, nTMS can provide new biomarkers of motor function impairment in pwMS. Our study opens perspectives for the use of nTMS as an objective method for assessing pwMS disability in clinical practice.

Characteristics of motor evoked potentials in patients with peripheral vascular disease.

With an aging population, it is common to encounter people diagnosed with peripheral vascular disease (PVD). Some will undergo surgeries during which the spinal cord may be compromised and intraoperative neuromonitoring with motor evoked potentials (MEPs) is employed to help mitigate paralysis. No data exist on characteristics of MEPs in older, PVD patients, which would be valuable for patients undergoing spinal cord at-risk surgery or participating in neurophysiological research. Transcranial magnetic stimulation, which can be delivered to the awake patient, was used to stimulate the motor cortex of 20 patients (mean (±SD)) age 63.2yrs (±11.5) with confirmed PVD, every 10 minutes for one hour with MEPs recorded from selected upper and lower limb muscles. Data were compared to that from 20 healthy volunteers recruited for a protocol development study (28yrs (±7.6)). MEPs did not differ between patient's symptomatic and asymptomatic legs. MEP amplitudes were not different for a given muscle between patients and healthy participants. Except for vastus lateralis, disease severity did not correlate with MEP amplitude. There were no differences over time in the coefficient of variation of MEP amplitude at each time point for any muscle in patients or in healthy participants. Although latencies of MEPs were not different between patients and healthy participants for a given muscle, they were longer in older participants. The results obtained suggest PVD alone does not impact MEPs; there were no differences between more symptomatic and less symptomatic legs. Further, in general, disease severity did not corelate with MEP characteristics. With an aging population, more patients with PVD and cardiovascular risk factors will be participating in neurophysiological studies or undergoing surgery where spinal cord integrity is monitored. Our data show that MEPs from these patients can be easily evoked and interpreted.

Brain Mapping – Neuromuscular correlations in long-term Postsurgical rehabilitation of Adult Brachial Plexus Palsies

Abstract: Background: Correlations of Transcranial magnetic stimulation (TMS) mapping of the cortical area and electromyography (EMG) + dynamometric testing may demonstrate active neuroplas-ticity events that are reliant on rehabilitation therapy (RT) compliance in adult postsurgical brachial plexus (BP) injuries. Material and Methods: On the right (dominant) arm of two patients with chronic operated BP lesions, we evaluated the progress of functional recovery. The trau-matic event was dated more than 10 years ago for both patients. The first patient (male, 50 years old) and the second one (female, 58 years old) had a history of several microsurgical neurotiza-tion and muscle transfer procedures, with less amelioration of the motor deficit, especially re-lated to elbow flexion (MRC 1/5 and 2/5, respectively). We followed up their evolution by EMG parameters, dynamometry, MRC scaling, and TMS. The motor region of the limb was mapped using TMS to assess the amplitudes of the motor evoked potentials (MEP), on a 4-axis protocol. The patients were assessed twice, with the second examination performed after RT had just fin-ished. TMS findings were compared with EMG and dynamometric results. Results: Higher MEP amplitudes were associated with improved MEP latency during stimulation of the left cerebral hemisphere's cortical area, as well as at the cervical level. EMG findings, both nerve conduction and needle EMG studies showed nonsignificant improvements, as well as muscle strength (as measured by the hydraulic dynamometer). The best results for the first patient showed an in-crease in MEP’s amplitude increase from 1.08 mV to 1.49 mV (in the hotspot), which correlated with measurable latencies, as compared to the first TMS (when no response was obtained at cer-vical stimulation). The second patient also had improvements in latencies: from 37.1 msec. to 36.3 msec. (cervical stimulation with recording at bicipital level) and from 39.2 msec. to 37.9 (cervical stimulation recording at the first interosseous), with a hotspot increase from 1.35 mV to 1.98 mV. The results demonstrate cortical region reactivity in regard to therapeutic techniques. Central modifications do not correlate with visible EMG and dynamometric improvements. Pa-tients with traumatic BP palsy may receive several microsurgical reconstructive procedures, nevertheless, the rehabilitation of the upper limb’s functionality may sometimes still be limited. This increases the risk of discontinuity of the neuromotor RT. We aim to prove that in spite of little correlations with clinical and EMG findings, mapping the cortical area using TMS provides proof of ongoing neuroplasticity phenomena, dependent on adherence to RT. Conclusion: The evidence of continued brain activity supports the requirement for long-term adherence to treatment guidelines and long-term study protocols.

A pig model of symptomatic spinal epidural hematoma.

The purpose of this study was to establish an animal model capable of simulating the development and decompression process of symptomatic spinal epidural hematoma (SSEH). A total of 16 male Bama miniature pigs were included in this study and randomly allocated into four groups: Group A (4h 20mmHg hematoma compression), Group B (4h 24mmHg hematoma compression), Group C (4h 28mmHg hematoma compression), and Group Sham (control). Real-time intra-wound hematoma compression values were obtained using the principle of connectors. Electrophysiological analyses, including the latency and amplitude of somatosensory evoked potentials (SSEP) and motor evoked potentials (MEP), along with behavioral observations (Tarlov score), were performed to assess this model. ANOVA tests demonstrated significant differences in the latency and relative amplitude of SSEP and MEP between Groups C and Sham after 4h of hematoma compression and one month after surgery (P < 0.01). Behavioral assessments 8h after surgery indicated that animals subjected to 28mmHg hematoma compression suffered the most severe spinal cord injury. Pearson correlation coefficient test suggested a negative correlation between the epidural pressure and Tarlov score (r = -0.700, p < 0.001). With the progression of compression and the escalation of epidural pressure, the latency of SSEP and MEP gradually increased, while the relative amplitude gradually decreased. When the epidural pressure reaches approximately 24mmHg, the spinal cord function occurs progressive dysfunction. Monitoring epidural pressure would be an effective approach to assist to identify the occurrence of postoperative SSEH.

Evaluation of Epiconus and Conus Medullaris Disorders due to Thoracolumbar Vertebral Fracture using Motor-evoked Potentials.

A retrospective case-control study. To characterize the motor evoked potential (MEP) when the epiconus or conus medullaris is compressed by a fracture of the T12 or L1 vertebra. Although the characteristics of compressive cervical and thoracic myelopathy with transcranial magnetic stimulation MEP have been reported, the MEP parameters in compressive disorders of the epiconus and conus medullaris have not yet been characterized. Twenty patients with T12 or L1 vertebral fractures who had lower extremity symptoms due to compression of the epiconus or conus medullaris were included. These patients were compared with 28 healthy controls and 32 patients with cervical spondylotic radiculopathy (CSR) without spinal cord compression. MEPs of abductor hallucis muscles were recorded using transcranial magnetic stimulation and electrical stimulation of the tibial nerve. MEP latency, central motor conduction time (CMCT), and peripheral conduction time (PCT) were evaluated. MEP latency, CMCT, and PCT were significantly longer in patients with fractures than in healthy controls and patients with CSR. MEP latency was most accurate for differentiating patients with fracture from healthy controls (cutoff value, 40.0 ms, sensitivity, 95.0%; specificity, 100%), and CMCT was most accurate for comparing patients with fracture and CSR (cutoff value, 15.5 ms, sensitivity, 80.0%; specificity, 93.8%). In the distinction between patients with fracture and CSR, 16 of the 20 patients with fracture exceeded the cutoff values for any of the parameters, and 12 of them exceeded the cutoff values for all parameters. There was no significant correlation between the linear distance from the most inferior end of the spinal cord to the site of compression and any of the MEP parameters. Both CMCT and PCT are often prolonged in compressive lesions of the epiconus and conus medullaris, and MEP latency and CMCT are useful in the diagnosis.

Transcutaneous auricular vagus nerve stimulation with task-oriented training improves upper extremity function in patients with subacute stroke: a randomized clinical trial.

Transcutaneous auricular vagus nerve stimulation (taVNS) has emerged as a promising brain stimulation modality in poststroke upper extremity rehabilitation. Although several studies have examined the safety and reliability of taVNS, the mechanisms underlying motor recovery in stroke patients remain unclear. This study aimed to investigate the effects of taVNS paired with task-oriented training (TOT) on upper extremity function in patients with subacute stroke and explore the potential underlying mechanisms. In this double-blinded, randomized, controlled pilot trial, 40 patients with subacute stroke were randomly assigned to two groups: the VNS group (VG), receiving taVNS during TOT, and the Sham group (SG), receiving sham taVNS during TOT. The intervention was delivered 5 days per week for 4 weeks. Upper extremity function was measured using the Fugl-Meyer Assessment-Upper Extremity (FMA-UE), the Action Research Arm Test (ARAT). Activities of daily living were measured by the modified Barthel Index (MBI). Motor-evoked potentials (MEPs) were measured to evaluate cortical excitability. Assessments were administered at baseline and post-intervention. Additionally, the immediate effect of taVNS was detected using functional near-infrared spectroscopy (fNIRS) and heart rate variability (HRV) before intervention. The VG showed significant improvements in upper extremity function (FMA-UE, ARAT) and activities of daily living (MBI) compared to the SG at post-intervention. Furthermore, the VG demonstrated a higher rate of elicited ipsilesional MEPs and a shorter latency of MEPs in the contralesional M1. In the VG, improvements in FMA-UE were significantly associated with reduced latency of contralesional MEPs. Additionally, fNIRS revealed increased activation in the contralesional prefrontal cortex and ipsilesional sensorimotor cortex in the VG in contrast to the SG. However, no significant between-group differences were found in HRV. The combination of taVNS with TOT effectively improves upper extremity function in patients with subacute stroke, potentially through modulating the bilateral cortex excitability to facilitate task-specific functional recovery.

"Real-Time Neuromonitoring" Increases the Safety and Non-Invasiveness and Shortens the Duration of Idiopathic Scoliosis Surgery.

Introduction: A practical solution to the incidental unreliability of intraoperative neuromonitoring (IONM) may be the simultaneous neurophysiological recording and control of the surgical field through a camera (the concept of "Real-time" IONM). During "Real-time" IONM, the surgeon is immediately warned about the possibility of damage to the neural structures during, but not after, standard idiopathic scoliosis (IS) corrective surgery procedures (the concept of "Surgeon-neurophysiologist" interactive, verbal IONM). This study aimed to compare the advantages, utilities, reliabilities, and time consumption of the two IONM scenarios. Methods: Studies were performed in two similar groups of patients undergoing surgery primarily due to Lenke 2 idiopathic scoliosis (N = 120), when both IONM approaches were applied. Neurophysiological evaluations of the spinal transmission were performed pre- (T0), intra- (before (T1) and after (T2) surgery), and postoperatively (T3), as well as once in healthy volunteers (control, N = 60). Non-invasive and innovative recordings of the motor evoked potentials (MEPs) bilaterally from the peroneal (PER) nerve and tibialis anterior (TA) muscle were performed with surface electrodes as a result of transcranial magnetic stimulation (TMS) or electrical stimulation (TES) at T0-T3. Results: In both groups, the MEP amplitudes and latencies recorded from the PER nerve were approximately 67% lower and 3.1 ms shorter than those recorded from the TA muscle. The MEP recording parameters differed similarly at T0-T3 compared to the control group. In all patients, the MEP parameters induced by TMS (T0) and TES (T1) did not differ. The MEP amplitude parameters recorded from the TA and PER at T1 and T2 indicated a bilateral improvement in the neural spinal conduction due to the surgical intervention. The TMS-induced MEP amplitude at T3 further increased bilaterally. In both IONM groups, an average 51.8 BIS level of anesthesia did not affect the variability in the MEP amplitude, especially in the PER recordings when the applied TES strength was 98.2 mA. The number of fluctuations in the MEP parameters was closely related to the number of warnings from the neurophysiologist during the transpedicular screw implantation, corrective rod implantation, and distraction, derotation, and compression procedures, and it was higher in the "Surgeon-neurophysiologist" IONM group. The average duration of surgery was shorter by approximately one hour in the "Real-time" IONM group. The number of two-way communications between the surgeon and the neurophysiologist and vice versa in the "Real-time" IONM group decreased by approximately half. Conclusions: This study proves the superiority of using "Real-time" IONM over the standard "Surgeon-neurophysiologist" IONM procedure in increasing the safety and non-invasiveness, shortening the time, and lowering the costs of the surgical treatment of IS patients. The modifications of the MEP nerve-conduction-recording technology with surface electrodes from nerves enable precise and reliable information on the pediatric patient's neurological condition at every stage of the applied surgical procedures, even under conditions of slight fluctuations in anesthesia.

Evoked potentials after autologous hematopoietic stem cell transplantation for multiple sclerosis

ObjectiveTo investigate the effect of autologous hematopoietic stem cell transplantation (AHSCT) on functional aspects of the nervous system assessed by visual (VEP), somatosensory (SEP), and motor (MEP) evoked potentials in patients with relapsing-remitting multiple sclerosis. BackgroundSeveral studies have demonstrated the efficacy of AHSCT on inflammatory activity and disability progression in patients with multiple sclerosis. However, the impact of AHSCT on evoked potentials has not been evaluated before. MethodsTwelve AHSCT-treated patients from Uppsala University Hospital were consecutively recruited. Evoked potentials (EP) were collected at baseline and two follow-up visits, 3 and 12 months post-AHSCT. We calculated a composite EP score for each participant and compared it between different time points. ResultsThe median total EP score decreased from 5 at baseline, to 2.5 at 12 months post-ASHCT (p = 0.008). A significant improvement in tibial SEP (tSEP) latencies was observed (42.7 vs 41.5 ms, p < 0.001), with a similar trend for MEP latencies 12 months post-ASHCT. No significant changes in median SEP or VEP latencies were observed. ConclusionsTreatment with AHSCT was associated with improved transmission in some central nervous system pathways in multiple sclerosis patients.

Central and Peripheral Motor Conduction Studies by Single-Pulse Magnetic Stimulation.

Single-pulse magnetic stimulation is the simplest type of transcranial magnetic stimulation (TMS). Muscle action potentials induced by applying TMS over the primary motor cortex are recorded with surface electromyography electrodes, and they are called motor-evoked potentials (MEPs). The amplitude and latency of MEPs are used for various analyses in clinical practice and research. The most commonly used parameter is the central motor conduction time (CMCT), which is measured using motor cortical and spinal nerve stimulation. In addition, stimulation at the foramen magnum or the conus medullaris can be combined with conventional CMCT measurements to evaluate various conduction parameters in the corticospinal tract more precisely, including the cortical-brainstem conduction time, brainstem-root conduction time, cortical-conus motor conduction time, and cauda equina conduction time. The cortical silent period is also a useful parameter for evaluating cortical excitability. Single-pulse magnetic stimulation is further used to analyze not only the central nervous system but also the peripheral nervous system, such as for detecting lesions in the proximal parts of peripheral nerves. In this review article we introduce four types of single-pulse magnetic stimulation-of the motor cortex, spinal nerve, foramen magnum, and conus medullaris-that are useful for the diagnosis, elucidation of pathophysiology, and evaluation of clinical conditions and therapeutic effects. Single-pulse magnetic stimulation is a clinically useful technique that all neurologists should learn.

Evaluation of bidirectional gut-brain axis and anorectal function in Parkinson's disease with constipation.

Parkinson's disease (PD) is a neurodegenerative movement disorder with prodromal and highly prevalent gastrointestinal (GI) symptoms, especially constipation. Although PD models suggest gut-brain axis dysfunction, the mechanistic underpinnings and their correlation with GI symptoms are poorly understood. To examine the bidirectional gut-brain axis function in PD and correlate it with constipation severity, PD duration, and severity. Rectal sensory thresholds and afferent cortical evoked potentials (CEP) were assessed using a 4-ring EMG electrode probe. Efferent anal and rectal motor evoked potentials (MEPs) were obtained following transcranial and lumbosacral magnetic stimulation. Bowel symptoms were assessed by prospective stool diary. The CEP and MEP latencies, rectal sensory thresholds, and anorectal sensorimotor data were compared between PD subjects and age-adjusted healthy subjects. Twenty-five PD subjects with constipation (F/M = 6/19) and 20 healthy subjects (F/M = 14/6) were enrolled. The first and pain sensation thresholds were higher in PD subjects than healthy subjects (p < 0.002) but lost significance after adjustment for age. Age-adjusted rectal CEP and right-sided cortico-anal MEP latencies were prolonged in PD subjects compared to healthy subjects (p < 0.04). Also, half (4 of 8) age-adjusted spino-anal and rectal MEP latencies in PD subjects were significantly longer. In multivariate linear analysis, first rectal sensation and right-sided MEP latencies showed moderate correlation with constipation severity. Parkinson's disease is associated with significant bidirectional gut-brain axis dysfunction as evidenced by prolonged afferent and efferent neuronal signaling. Constipation severity in PD is correlated to abnormal rectal sensation and lateralized disturbance of efferent brain-gut signaling.