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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.
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Background: Multiple sclerosis (MS) is an immune-mediated neurodegenerative disease that involves attacks of inflammatory demyelination and axonal damage, with variable but continuous disability accumulation. Transcranial magnetic stimulation (TMS) is a noninvasive method to characterize conduction loss and axonal damage in the corticospinal tract. TMS as a technique provides indices of corticospinal tract function that may serve as putative MS biomarkers. To date, no reviews have directly addressed the diagnostic performance of TMS in MS. The authors aimed to conduct a critical narrative review on the diagnostic performance of TMS in MS. Methods: The authors searched the Embase, PubMed, Scopus, and Web of Science databases for studies that reported the sensitivity and/or specificity of any reported TMS technique compared to established clinical MS diagnostic criteria. Studies were summarized and critically appraised for their quality and validity. Results: Seventeen of 1,073 records were included for data extraction and critical appraisal. Markers of demyelination and axonal damage-most notably, central motor conduction time (CMCT)-were specific, but not sensitive, for MS. Thirteen (76%), two (12%), and two (12%) studies exhibited high, unclear, and low risk of bias, respectively. No study demonstrated validity for TMS techniques as diagnostic biomarkers in MS. Conclusions: CMCT has the potential to: (1) enhance the specificity of clinical MS diagnostic criteria by "ruling in" true-positives, or (2) revise a diagnosis from relapsing to progressive forms of MS. However, there is presently insufficient high-quality evidence to recommend any TMS technique in the diagnostic algorithm for MS.
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CME-Carbodiimida/análogos & derivados , Esclerosis Múltiple , Enfermedades Neurodegenerativas , Humanos , Esclerosis Múltiple/diagnóstico , Estimulación Magnética Transcraneal/métodos , BiomarcadoresRESUMEN
BACKGROUND: The recovery of walking capacity is of great significance in stroke rehabilitation. We evaluated changes in post-stroke gait function after low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) treatment. METHODS: Stroke patients were randomly assigned to control (conventional treatment)/LF-rTMS (LF-rTMS treatment based on conventional treatment) groups. Gait spatiotemporal parameters/affected side joint motion angle/affected side dynamic parameters were analyzed by 3D gait analyses. Motor evoked potential (MEP)/central motor conduction time (CMCT) changes were detected. Correlations between MEP latency/CMCT and gait parameters after LF-rTMS were analyzed by Pearson analysis. RESULTS: The two groups exhibited boosted stride speed/frequency/length, affected side stride length/swing phase percentage/hip/knee/ankle joint plantar flexion angle, and affected side ahead ground reaction force/ upward ground reaction force (AGRF/UGRF)/ankle joint plantar flexion moment, along with reduced affected side gait period/stance phase percentage after treatment, and the LF-rTMS group manifested better efficacy. MEP latency/CMCT of stroke patients treated with LF-rTMS was adversely linked to stride speed, affected side stride length/swing phase percentage/knee flexion angle, AGRF and UGRF, and positively correlated with affected side stance phase percentage. CONCLUSION: LF-rTMS significantly improved gait spatiotemporal parameters/affected joint motion angles/neurophysiologic parameters (MEP latency/CMCT) in patients with post-stroke walking dysfunction. MEP latency/CMCT after LF-rTMS treatment were prominently correlated with gait parameters. Relative to the traditional scale assessment, we provided a more accurate, objective and reliable evaluation of the effects of LF-rTMS on lower limb mobility and functional recovery effects in stroke patients from the perspective of 3D gait analysis and neurophysiology, which provided more evidence to support the clinical application of LF-rTMS in post-stroke walking dysfunction treatment.
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CME-Carbodiimida/análogos & derivados , Accidente Cerebrovascular , Estimulación Magnética Transcraneal , Humanos , Análisis de la Marcha , Caminata , Marcha , Accidente Cerebrovascular/complicaciones , Accidente Cerebrovascular/terapiaRESUMEN
BACKGROUND: Spinocerebellar ataxia type 12 (SCA-12) is an uncommon autosomal dominant cerebellar ataxia characterized by action tremors in the upper limbs, dysarthria, head tremor, and gait ataxia. We aimed to evaluate the motor cortical excitability in patients with SCA-12 using transcranial magnetic stimulation (TMS). METHODS: The study was done in the department of Neurology at the National Institute of Mental Health and Neuro Sciences (NIMHANS), Bangalore. Nine patients with SCA-12 (2 females) and 10 healthy controls (2 females) were included in the study. TMS was performed in all the subjects and various parameters such as resting motor threshold (RMT), central motor conduction time (CMCT) and contralateral silent period (cSP) were recorded. The left motor cortex was stimulated and the recording was done from right first dorsal interossei muscle. The severity of ataxia was assessed using the scale for assessment and rating in ataxia (SARA). RESULTS: The mean age of the patients was 58.11 ± 7.56 years mean age at onset: 51.67 ± 4.18 years. The mean duration of illness was 9.44 ± 4.88 years. The mean SARA score was 13.83 ± 3.60. Patients with SCA-12 had significantly increased RMT (88.80 ± 12.78 %) compared to HC (44.90 ± 9.40 %, p < 0.05). A significantly prolonged CMCT was observed in patients (13.70 ± 2.52 msec) compared to HC (7.31 ± 1.21 msec, p < 0.05). In addition, cSP was significantly increased in SCA-12 patients (144.43 ± 25.79 msec) compared to HC (82.14 ± 28.90 msec, p < 0.05). CONCLUSIONS: Patients with SCA-12 demonstrate a reduced cortical excitability and increased cortical inhibition suggesting an increase in the GABAergic neurotransmission.
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CME-Carbodiimida/análogos & derivados , Ataxia Cerebelosa , Excitabilidad Cortical , Ataxias Espinocerebelosas , Femenino , Humanos , Persona de Mediana Edad , Anciano , Potenciales Evocados Motores/fisiología , India , Temblor/etiología , Estimulación Magnética TranscranealRESUMEN
Background: Differentiating between physiologic and altered motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) is crucial in clinical practice. Some physical characteristics, such as height and age, introduce sources of variability unrelated to neural dysfunction. We provided new age- and height-adjusted normal values for cortical latency, central motor conduction time (CMCT), and peripheral motor conduction time (PMCT) from a large cohort of healthy subjects. Methods: Previously reported data from 587 participants were re-analyzed. Nervous system disorders were ruled out by clinical examination and magnetic resonance imaging. MEP latency was determined as stimulus-to-response latency through stimulation with a circular coil over the "hot spot" of the First Dorsal Interosseous and Tibialis Anterior muscles, during mild tonic contraction. CMCT was estimated as the difference between MEP cortical latency and PMCT by radicular magnetic stimulation. Additionally, right-to-left differences were calculated. For each parameter, multiple linear regression models of increasing complexity were fitted using height, age, and sex as regressors. Results: Motor evoked potential cortical latency, PMCT, and CMCT were shown to be age- and height-dependent, although age had only a small effect on CMCT. Relying on Bayesian information criterion for model selection, MEP cortical latency and PMCT were explained best by linear models indicating a positive correlation with both height and age. Also, CMCT to lower limbs positively correlated with height and age. CMCT to upper limbs positively correlated to height, but slightly inversely correlated to age, as supported by non-parametric bootstrap analysis. Males had longer cortical latencies and CMCT to lower limbs, as well as longer PMCT and cortical latencies to upper limbs, even when accounting for differences in body height. Right-to-left-differences were independent of height, age, and sex. Based on the selected regression models, sex-specific reference values were obtained for all TMS-related latencies and inter-side differences, with adjustments for height and age, where warranted. Conclusion: A significant relationship was observed between height and age and all MEP latency values, in both upper and lower limbs. These set of reference values facilitate the evaluation of MEPs in clinical studies and research settings. Unlike previous reports, we also highlighted the contribution of sex.
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Objective: Using transcranial magnetic stimulation (TMS) to delineate upper motor neuron (UMN) signs of two neurodegenerative disorders: amyotrophic lateral sclerosis (ALS) and multiple system atrophy (MSA). Methods: Medical records including clinical signs for UMN damage and TMS results were reviewed retrospectively. The UMN signs were classified into none, mild, and severe based on neurological examination of various reflexes. Then TMS-elicited motor evoked potentials (MEPs) were recorded from a hand and a leg muscle to calculate the central motor conduction time (CMCT), which represents fast, mono-synaptic conduction along the corticospinal tract. Relations between the UMN signs and CMCT were analysed for the two diseases. Results: Prevalence and severity of the UMN signs for ALS and MSA were comparable for both upper and lower limbs. However, abnormality in CMCT was found more frequently in ALS: CMCT abnormalities were found in upper limbs for 44% in ALS patients but only for 7% in MSA patients; CMCT abnormalities in lower limbs were 55% in ALS and 20% in MSA. Some ALS patients showed abnormal CMCT in limbs without UMN signs, which was not true for most MSA patients. Conclusions: The abnormalities of CMCT were different in ALS and MSA, even for those who clinically had similar UMN signs. Sometimes, CMCT can reveal UMN damage in the absence of clinical UMN signs. Differences presumably derive from selective degeneration of different fibres in the motor descending pathways. Longitudinal studies must be conducted to accumulate neuroimaging and pathological findings. Significance: CMCT can be useful to differentiate ALS and MSA.
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Purpose. Brainstem syndromes have frequently been reported in Chiari syndrome and in syringobulbia; previous studies have shown that determining the central motor conduction time (CMCT) along the circuit of the phrenic nerve makes the assessment of the voluntary control of the respiratory pathway possible. In our study, we evaluated the transcranial magnetic stimulation (TMS) of the phrenic nerve in patients affected by Chiari syndrome and/or syringomyelia (Syr) with the aim of identifying subclinical neurophysiological alterations. Methods. One hundred patients (75 females; average age: 51 ± 13.08 SD; range: 18-76) affected by Chiari syndrome and/or Syr without dyspnea were selected. The magnetic stimulation of the second motor neuron correlating with the phrenic nerve was performed using cervical magnetic stimulation (C5-MEP); the cortical MEP after magnetic stimulation (Cz-MEP) was recorded by magnetic stimulation of the motor cortex (areas corresponding to the diaphragm). The CMCT was calculated. The differences between the patients and controls were calculated (Student's t test). Results. In 13% of the patients, the Cz-MEP were absent bilaterally, and the CMCT was not evaluable. In all these cases, bulbar/cervical Syr was present at MRI; in 10 of them, this was associated with CM1. A bilateral response was obtained in all the other patients (87%), and the CMCTs were normal. All the patients with alterations/absence of Cz-MEP presented bulbar/cervical Syr at MRI. The C5-MEP latency was prolonged or absent in 48%; of these, 84% presented bulbar/cervical Syr associated with CM1 at MRI. The C5-MEP latency values were significantly higher in the group of patients. Conclusions. Neurophysiological alterations of the diaphragmatic pathway were recorded in a group of Chiari syndrome and, particularly, in bulbar/cervical Syr. Future studies with larger cohorts of patients are needed to further assess the specific role of the TMS of the phrenic nerve in CM/Syr patients.
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PURPOSE: This study aims to characterize tight filum terminale (TFT) in motor evoked potential (MEP) testing by comparing TFT patients with both tethered cord syndrome (TCS) patients and healthy subjects. METHODS: Fifty TFT patients, 18 TCS patients, and 35 healthy volunteers participated in this study. We recorded MEPs following transcranial magnetic stimulation from the bilateral abductor hallucis muscles as well as compound muscle action potentials and F-waves evoked by electrical stimulation of the tibial nerve from the bilateral abductor pollicis brevis muscles. The peripheral conduction time (PCT) was calculated from the latency of the compound action potential and F-wave. Furthermore, the central motor conduction time (CMCT) was calculated by subtracting PCT from MEP latency. RESULTS: TFT and TCS patients had a significantly longer MEP latency than healthy subjects. PCT in TFT patients was significantly longer than those in TCS patients or healthy subjects. Using the cutoff values for PCT, we were able to diagnose patients with TFT patients with a sensitivity of 72.0% and a specificity of 91.4%. CONCLUSION: Prolonged PCT in the MEP test may be a useful indicator for TFT and suggests that MEP may be used as an adjunct diagnostic tool for TFT.
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Cauda Equina , Defectos del Tubo Neural , Potenciales Evocados Motores/fisiología , Humanos , Conducción Nerviosa/fisiología , Defectos del Tubo Neural/diagnóstico , Estimulación Magnética TranscranealRESUMEN
INTRODUCTION: In persons with multiple sclerosis, nerve conductivity can be reduced. The assessment is generally performed via motor evoked potentials (MEP). So far, a strongly associated motor performance surrogate for changes in the extracted central motor conduction time (CMCT) is missing. METHODS: CMCT and performance in the nine-hole peg test and maximum thumb tapping frequencies over 10 s of 12 persons with multiple sclerosis were measured prior to and after training over 5 consecutive days. Each training consisted of 10,000 thumb taps at maximum effort with the dominant upper limb. RESULTS: The dominant upper limb improved in maximum tapping frequency over 10 s (d = 0.79) and 10,000 taps (d = 1.04), the nine-hole peg test (d = 0.60), and CMCT (d = 0.52). The nondominant upper limb only improved in the nine-hole peg test (d = 0.38). Models of multiple linear regression predicted 0.78 (model 1, tapping performance as factors) and 0.87 (model 2, patient baseline characteristics as factors) of the variance in CMCT changes. DISCUSSION: Changes in CMCT were well predictable, although the assessment of those surrogates is either not economic (model 1) or rather describing a potential of change (model 2). However, we were able to show moderate changes in CMCT within 5 days.
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Esclerosis Múltiple , Potenciales Evocados Motores/fisiología , Humanos , Esclerosis Múltiple/diagnóstico , Conducción Nerviosa/fisiología , Pulgar , Estimulación Magnética TranscranealRESUMEN
Activation and reconstruction of the spinal cord circuitry is important for improving motor function following spinal cord injury. We conducted a case series study to investigate motor function improvement in 14 patients with chronic spinal cord injury treated with 4 weeks of unilateral (right only) cortical intermittent theta burst stimulation combined with bilateral magnetic stimulation of L3-L4 nerve roots, five times a week. Bilateral resting motor evoked potential amplitude was increased, central motor conduction time on the side receiving cortical stimulation was significantly decreased, and lower extremity motor score, Berg balance score, spinal cord independence measure-III score, and 10 m-walking speed were all increased after treatment. Right resting motor evoked potential amplitude was positively correlated with lower extremity motor score after 4 weeks of treatment. These findings suggest that cortical intermittent theta burst stimulation combined with precise root stimulation can improve nerve conduction of the corticospinal tract and lower limb motor function recovery in patients with chronic spinal cord injury.
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Patients with cervical spondylotic myelopathy (CSM) often exhibit symptoms in clinical practice, particularly the elderly, whose lower extremity functions are more likely to deteriorate; however, the underlying mechanisms currently remain unclear. The present study aimed to elucidate the relationship between the neurological severity of CSM based on an electrophysiological examination and radiological findings. Eighty-six patients with CSM were examined using kinematic CT myelography. The cross-sectional area of the spinal cord and dynamic changes in the spinal cord were measured at the affected level. The central motor conduction time (CMCT) using transcranial magnetic stimulation was calculated as follows: motor evoked potential latency - (compound muscle action potential latency + F latency - 1)/2 (ms). A multiple logistic regression analysis was performed to identify the radiological parameters associated with severe lower limb dysfunction. CMCT in the upper limbs correlated with spinal cord compression during neck extension, while that in the lower limbs correlated with a larger C2-7 sagittal vertical axis, cervical lordosis, a small C2-7 range of motion (ROM), and spinal cord compression during neck flexion. In a multiple logistic regression analysis, significant risk factors specific for severe lower limb dysfunction were greater anterior spondylolisthesis during neck extension (P = 0.006, OR: 2.53, 95%CI: 1.13-2.07) and small C2-7 ROM in neutral to flexion (P = 0.035, OR: 0.67, 95%CI: 0.52-0.88). Imaging findings affect upper and lower extremity functions in specific manners. Cervical stiffness or anterior compression factors may be associated with the deterioration of lower limb function.
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Mielografía , Enfermedades de la Médula Espinal , Anciano , Fenómenos Biomecánicos , Humanos , Conducción Nerviosa , Tractos Piramidales/diagnóstico por imagen , Enfermedades de la Médula Espinal/complicaciones , Enfermedades de la Médula Espinal/diagnóstico por imagen , Tomografía Computarizada por Rayos XRESUMEN
OBJECTIVES: We investigated the relationship between pyramidal tract evaluation indexes (i.e., diffusion tensor imaging, transcranial magnetic stimulation (TMS)-induced motor-evoked potential (MEP), and central motor conduction time (CMCT) on admission to the recovery rehabilitation unit) and motor functions at discharge in patients with ischemic or hemorrhagic stroke. MATERIALS AND METHODS: Seventeen patients were recruited (12 men; 57.9 ± 10.3 years). The mean fractional anisotropy (FA) values of the right and left posterior limbs of the internal capsule were estimated using a computer-automated method. We determined the ratios of FA values in the affected and unaffected hemispheres (rFA), TMS-induced MEP, and the ratios of CMCT in the affected and unaffected hemispheres (rCMCT) and examined their association with motor functions (Fugl-Meyer Assessment (FMA) and Action Research Arm Test (ARAT)) at discharge. RESULTS: Higher rFA values of the posterior limb of the internal capsule on admission to the recovery rehabilitation unit led to a better recovery of upper limb function (FMA: r = 0.78, p < 0.001; ARAT: r = 0.74, p = 0.001). Patients without MEP had poorer recovery of upper limb function than those with MEP (FMA: p < 0.001; ARAT: p = 0.001). The higher the rCMCT, the poorer the recovery of upper limb function (ARAT: r = -0.93, p < 0.001). However, no association was observed between the pyramidal tract evaluation indexes and recovery of lower limb motor function. CONCLUSIONS: Evaluating the pyramidal tract is useful for predicting upper limb function prognosis, but not for lower limb function prognosis.
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Imagen de Difusión Tensora , Accidente Cerebrovascular Hemorrágico/terapia , Accidente Cerebrovascular Isquémico/terapia , Actividad Motora , Examen Neurológico , Tractos Piramidales/diagnóstico por imagen , Tractos Piramidales/fisiopatología , Rehabilitación de Accidente Cerebrovascular , Adulto , Anciano , Potenciales Evocados Motores , Femenino , Estado Funcional , Accidente Cerebrovascular Hemorrágico/diagnóstico por imagen , Accidente Cerebrovascular Hemorrágico/fisiopatología , Humanos , Accidente Cerebrovascular Isquémico/diagnóstico por imagen , Accidente Cerebrovascular Isquémico/fisiopatología , Masculino , Persona de Mediana Edad , Conducción Nerviosa , Admisión del Paciente , Alta del Paciente , Valor Predictivo de las Pruebas , Recuperación de la Función , Estudios Retrospectivos , Estimulación Magnética Transcraneal , Resultado del TratamientoRESUMEN
BACKGROUND: This report depicts a rare case of acutely developed urinary retention as well as sensory and motor disturbances caused by formation of a large hematoma within the piriformis muscle, which caused compression of nerves within the suprapiriform and infrapiriform foramina, thus imitating cauda equina syndrome. Although cases of acute lumbosacral plexopathy have been described, this case is the first time both urinary retention and sensory and motor disturbances were present. OBSERVATIONS: The most useful tools for diagnosis of acute piriformis syndrome are detailed patient history, magnetic resonance imaging (MRI) of the pelvic region, and electrophysiological testing performed by an experienced electrophysiologist. As a result of diligent rehabilitation, including physiotherapy and electrostimulation, the patient was able to successfully recover, regardless of acute compression of the sacral plexus that lasted 6 days. LESSONS: Clinicians should actively ask about previous pelvic trauma when taking a patient history in similar cases, especially if the patient is receiving anticoagulation treatment. If MRI of the lumbar spine does not reveal any pathologies, MRI of the pelvic region should be performed. Acute surgical decompression is crucial for preserving neurological function. In similar cases, it is possible to differentiate between spinal cord, cauda equina, and pelvic lesions using electrophysiological studies.
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The dominantly inherited spinocerebellar ataxias (SCAs) are a large class of neurodegenerative diseases. Transcranial magnetic stimulation has been used to evaluate the function of the pyramidal tract, and central motor conduction time (CMCT) is one index used to detect pyramidal tract dysfunction. We conducted a comprehensive search of PubMed, Embase and Web of Science. Eight eligible studies were included in the meta-analysis. For upper limb CMCT, the mean difference (95% confidence interval (CI)) between the combined SCA group and the control group was 2.24 [1.76-2.72], while the mean differences (95% CIs) between the subtypes and the control group were as follows: 4.43 [3.58-5.28] for SCA1, 0.25 [-0.15,0.65] for SCA2, 1.04 [-0.37,2.46] for SCA3 and 0.49 [-0.29,1.28] for SCA6. Additionally, SCA1 significantly differed from SCA2 and SCA3 in terms of CMCT (P=0.0006 and P=0.010, respectively). We also compared lower limb CMCT between the SCA2 and control groups. The mean difference (95% CI) was 6.58 [4.49-8.67], which was clearly statistically significant. The differences in CMCT values among different subtypes suggests diverse pathological mechanisms. In general, CMCT is a promising objective index to judge the severity of disease deserving further investigation.
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Conducción Nerviosa/fisiología , Ataxias Espinocerebelosas/diagnóstico , Ataxias Espinocerebelosas/fisiopatología , Estimulación Magnética Transcraneal , HumanosRESUMEN
OBJECTIVE: We retrospectively investigated the utility of the central motor conduction time (CMCT) in detecting upper motor neuron (UMN) involvements in patients with amyotrophic lateral sclerosis (ALS). METHODS: Fifty-two ALS patients and 12 disease control patients participated in this study. Surface electromyograms were recorded from the first dorsal interosseous (FDI) and tibialis anterior (TA) muscles. We stimulated the motor cortex, brainstem, and spinal nerve using transcranial magnetic stimulation (TMS) in order to measure the cortical, brainstem, and spinal latencies. We divided the ALS patients into 2 subgroups (with UMN impairment vs. without UMN impairment) and calculated the rates of abnormal CMCT prolongation judged by their comparison with the normal ranges obtained by the measurement in the control patients. RESULTS: The CMCTs in the FDI and TA were abnormally prolonged in over 40% of the ALS patients with UMN impairment and in nearly 30% of those without UMN impairment. CONCLUSIONS: CMCT shows UMN dysfunction in ALS patients without clinical UMN impairment. SIGNIFICANCE: TMS still has diagnostic utility in a significant portion of ALS patients.
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Esclerosis Amiotrófica Lateral/fisiopatología , Neuronas Motoras/fisiología , Conducción Nerviosa , Anciano , Tronco Encefálico/fisiopatología , Potenciales Evocados Motores , Femenino , Humanos , Masculino , Persona de Mediana Edad , Corteza Motora/fisiopatología , Músculo Esquelético/fisiopatología , Tiempo de Reacción , Nervios Espinales/fisiopatología , Estimulación Magnética TranscranealRESUMEN
Hyper-reflexia is occasionally seen in acute motor axonal neuropathy (AMAN), but its pathophysiology is unclear. We report a patient with AMAN following Campylobacter jejuni enteritis, who showed generalized hyper-reflexia, bilateral Hoffmann sign and right Babinski sign. MRI and transcranial magnetic stimulation of the motor cortex disclosed no corticospinal tract involvement. An extensive electrophysiological investigation documented α-motoneuron hyperexcitability and dysfunction of the interneuronal inhibitory circuits in the spinal anterior horn. We propose an immune-mediated damage of the spinal inhibitory interneuronal network as possible mechanism inducing hyper-reflexia in AMAN.
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Células del Asta Anterior/fisiología , Infecciones por Campylobacter/complicaciones , Síndrome de Guillain-Barré/fisiopatología , Reflejo Anormal/fisiología , Adulto , Potenciales Evocados Motores , Femenino , Síndrome de Guillain-Barré/etiología , Humanos , Masculino , Persona de Mediana Edad , Corteza Motora/fisiopatología , Conducción Nerviosa , Reflejo Anormal/inmunología , Estimulación Magnética TranscranealRESUMEN
[Objectives] In this study, we examined the effects of acupuncture stimulation on short latency reflexes (SLR) and long latency reflexes (LLR) to determine the site of acupuncture stimulation in modulating motor reflexes. Further, we investigated the relationship between changes in LLR and changes in the N20 somatosensory evoked potential (SEP) component induced by acupuncture stimulation and examined changes in central motor conduction time (CMCT).[Subjects and Methods] Sixteen healthy and right-handed adults (11 males and 5 females; 28.9 ± 6.6 years old; upper limb length 54.9 ± 3.2 cm) participated in this study. The experiments were performed under three conditions: (1) control (no acupuncture stimulation), (2) acupuncture stimulation of right-sided Hegu (LI4), and (3) acupuncture stimulation of left-sided LI4. An acupuncture needle (0.18 mm in diameter) was inserted up to a depth of 10 mm at the right- or left-sided LI4. Electrical stimulation was delivered to the median nerve in the right hand joint at a 120% intensity compared with the threshold to produce an M-wave. SLR and LLR were recorded from the opponens pollicis muscle of the right hand. The frequency and amplitude ratio of SLR (latency, approximately 20-30 ms) and LLR (latency, approximately 40-70 ms) were analyzed. SEP was produced by electrical stimulation delivered to the median nerve. The amplitude from baseline and mean latency of N20 waves were measured. F-wave in the evoked electromyography was evoked by electrical stimulation of the median nerve of the right hand at supramaximal intensity to elicit an M-wave and recorded from the opponens pollicis muscle of the same hand. We analyzed the mean latency and calculated the CMCT using the mean latencies of LLR, N20, F-wave, and M-wave.[Results] The frequency and amplitude ratio of SLR were reduced by acupuncture stimulation of left- and right-sided LI4, respectively. LLR frequency and amplitude ratio were reduced by acupuncture stimulations on either side. A correlation was observed between changes in the LLR amplitude ratio and changes in the N20 SEP amplitude ratio induced by acupuncture stimulation. No effect of acupuncture stimulation was observed on CMCT. [Discussion and Conclusion] SLR is the reflex potential of the spinal cord, and LLR is the motor reflex of the central nervous system via supraspinal pathways. These findings suggest that acupuncture stimulation inhibits motor nerve reflexes via both spinal and supraspinal modulation systems.
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BACKGROUND: McLeod syndrome is a rare X-linked recessive acanthocytosis associated with neurological manifestations including progressive chorea, cognitive impairment, psychiatric disturbances, seizures, and sensorimotor axonal polyneuropathy. However, no studies have investigated the functioning of central sensorimotor tracts in patients with McLeod syndrome. CASE PRESENTATION: A 66-year-old man had experienced slowly progressive chorea and gait disturbance due to lower limb muscle weakness since his early fifties. Blood examinations showed erythrocyte acanthocytosis and the reduction of Kell antigens in red blood cells. Brain magnetic resonance imaging showed atrophy of the bilateral caudate nuclei and putamen. The diagnosis of McLeod syndrome was confirmed by the presence of a mutation of the XK gene on the X chromosome. Somatosensory-evoked potential and transcranial magnetic stimulation studies demonstrated that the central sensory and motor conduction times were abnormally prolonged for the lower extremity but normal for the upper extremity. CONCLUSIONS: This is the first report of the involvement of the central sensorimotor tracts for the legs in a patient with McLeod syndrome. The clinical neurophysiological technique revealed the central sensorimotor tracts involvements clinically masked by neuropathy.
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Neuroacantocitosis/diagnóstico , Anciano , Atrofia , Humanos , Imagen por Resonancia Magnética , Masculino , Trastornos del Movimiento/etiología , Debilidad Muscular/etiología , MutaciónRESUMEN
INTRODUCTION: Motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) are known to be susceptible to several sources of variability. However, conflicting evidences on individual characteristics in relatively small sample sizes have been reported. We investigated the effect of age, height, and sex on MEPs of the motor cortex and spinal roots in a large cohort. METHODS: A total of 587 subjects clinically and neuroradiologically intact were included. MEPs were recorded during mild tonic contraction through a circular coil applied over the "hot spot" of the first dorsal interosseous and tibialis anterior muscles (TAs), bilaterally. Central motor conduction time (CMCT) was estimated as the difference between MEP cortical latency and the peripheral motor conduction time (PMCT) by cervical or lumbar magnetic stimulation. Peak-to-peak MEP amplitude to cortical stimulation and right-to-left difference of each parameter were also measured. RESULTS: After Bonferroni correction, general linear (multiple) regression analysis showed that both MEP cortical latency and PMCT at four limbs positively correlated with age and height. At lower limbs, an independent effect of sex on the same measures was also observed (with females showing smaller values than males). CMCT correlated with both age (negatively) and height (positively) when analyzed by a single regression; however, with a multiple regression analysis this significance disappeared, due to the correction for the multicollinearity within the dataset. CONCLUSION: Physical individual features need to be considered for a more accurate and meaningful MEPs interpretation. Both in clinical practice and in research setting, patients and controls should be matched for age, height, and sex.
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BACKGROUND AND PURPOSE: Cerebral small vessel disease (CSVD) is related to motor function disturbance. It includes several types: lacunar infarction, white matter hyperintensity, cerebral microbleeds (CMBs), and enlarged perivascular spaces (EPVS). Transcranial magnetic stimulation (TMS) has been successfully used to evaluate the function of the pyramidal tract. Central motor conduction time (CMCT) is one of the indicators of pyramidal tract dysfunction in motor evoked potential (MEP). The aim of this study was to investigate the association between each type of CSVD and CMCT. METHODS: We enrolled 350 patients with vascular risk factors or a history of cerebrovascular events, who showed signs of CSVD in magnetic resonance imaging in the prospective registry. Among them, 138 patients agreed to the evaluation of MEP. CMCT, resting motor threshold (RMT), and silent period are indicators of the function of motor pathways in MEP. A total of 276 hemispheres were divided into 45 symptomatic hemispheres with a history of pyramidal tract dysfunction and 231 without it. Correlation between each type of CSVD and CMCT were examined in total, symptomatic, and asymptomatic hemispheres. RESULTS: The mean age was 70.5 ± 10.3 (mean ± SD) years, and 89 (65%) were men. In the symptomatic hemisphere, CMCT and RMT were significantly higher than in the asymptomatic hemisphere. In the symptomatic hemisphere, significant association was observed between the number of EPVS in the white matter and CMCT (R2â¯=â¯0.201, pâ¯< .01). CONCLUSIONS: In the symptomatic hemispheres, CMCT was associated with the number of EPVS in the white matter. The EPVS in the white matter may be involved in the motor disturbance due to CSVD.