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Search for the word below: motor evoked potential
Number of hits: 56
JANUARY 30, 2021
Transcranial magnetic stimulation is a non-invasive procedure that uses robust magnetic fields to create an electrical current in the cerebral cortex. Dual stimulation consists of administering subthreshold conditioning stimulation (CS), then suprathreshold test stimulation (TS). When the interstimulus interval (ISI) is 1-6 msec, the motor evoked potential (MEP) decreases in amplitude; this decrease is termed “short interval intracortical inhibition” (SICI); when the ISI is 7-30 msec, an increase in MEP amplitude occurs, termed “short interval intracortical facilitation” (SICF). Continuous theta burst stimulation (cTBS), often applied at a frequency of 50 Hz, has been shown to decrease cortical excitability. The primary objective is to determine which duration of cTBS achieves better inhibition or excitation. The secondary objective is to compare 50 Hz cTBS to 30 Hz and 100 Hz cTBS. The resting motor threshold (rMT), MEP, SICI, and SICF were studied in 30 healthy volunteers. CS and TS were administered at 80%-120% and 70%-140% of rMT at 2 and 3-millisecond (msec) intervals for SICI, and 10- and 12-msec intervals for SICF. Ten individuals in each group received 30, 50, or 100 Hz, followed by administration of rMT, MT-MEP, SICI, SICF immediately and at 30 minutes. Greater inhibition was achieved with 3 msec than 2 msec in SICI, whereas better facilitation occurred at 12 msec than 10 msec in SICF. At 30 Hz, cTBS augmented inhibition and suppressed facilitation, while 50 Hz yielded less inhibition and greater inter-individual variability. At 100 Hz, cTBS provided slight facilitation in MEP amplitudes with less interindividual variability. SICI and SICF did not differ significantly between 50 Hz and 100 Hz cTBS. Our results suggest that performing SICI and SICF for 3 and 12 msec, respectively, and CS and TS at 80%-120% of rMT, demonstrate safer inhibition and facilitation. Recently, TBS has been used in the treatment of various neurological diseases, and we recommend preferentially 30 Hz over 50 Hz cTBS for better inhibition with greater safety and less inter-individual variability.
MARCH 30, 2016
Motor neuron diseases are disabling poor prognostic conditions, with no successful treatment. Repetitive transcranial magnetic stimulation might offer a temporary functional improvement. Objective - We intended to evaluate the extent of the functional improvement using electrophysiological and clinical tests. Methods - Patients with motor neuron disease (amyotrophic lateral sclerosis) were included. Muscle strength and respiratory function assessment represents the clinical approach, and central motor conduction time, motor unit number estimation, blink reflex and H-reflex stands for electrophysiology. Two tests were performed using the whole battery prior and after low frequency repetitive transcranial magnetic stimulation, using 1 Hz stimulation frequency for five consecutive days, 20 minutes daily, at 80% of the individual resting motor threshold. Results - Central motor conduction time, muscle strength and pulmonary function showed no statistically significant differences, but a tendency towards improvement. Motor unit number estimation, blink reflex and H-reflex showed a significantly better outcome after the five day repetitive transcranial magnetic stimulation treatment. Conclusion - Low frequency repetitive transcranial magnetic stimulation influences beneficially electrophysiological parameters in amyotrophic lateral sclerosis, but with little clinical impact; further studies are needed to validate the extent of the effect.
NOVEMBER 30, 2019
Background - Our objectives were to determine the differences in the vestibular evoked myogenic potential (VEMP) responses in patients diagnosed with early staged idiopathic Parkinson’s disease (PD) compared to the normal population and evaluate the vestibular system disorder causing balance-posture disorders. Second aim of this study was to investigate caloric test responses particularly in early staged PD compared to normal population. Material and methods - Thirty patients (14 females and 16 males; mean age, 60.6 ± 13.1 years) diagnosed with idiopathic PD and 28 healthy subjects (20 males and 8 females; mean age, 59.1 ± 6.4 years) were included. The patient and control groups were subdivided according to their age, gender and the patient group was subdivided according to onset time of the Parkinson symptoms, Hoehn-Yahr staging. The subgroups were compared for VEMP and caloric test responses. Results - There were no significant differences between the study and control groups for right and left VEMP measurements. Patients over 60 years and under 60 years did not show significant differences in terms of right and left mean VEMP measurements. However, P1 amplitude was significantly lower in patients over 60 years old (P = .004). Gender, disease duration, BERG balance scale and Hoehn-Yahr stage had no effect on the VEMP amplitudes. There was no significant correlation with the side of Parkinsonian symptoms to the side of canal paresis (P = .566) and the side on which no VEMP response was obtained in caloric test. Conclusion - VEMP responses were not different between PD and healthy subjects. VEMP P1 amplitude was decreased with age in PD group. Canal paresis and symptoms side were not statistically correlated in caloric test.
JULY 30, 2020
[The majority of patients with advanced Parkinson’s disease are treated at specialized movement disorder centers. Currently, there is no clear consensus on how to define the stages of Parkinson’s disease; the proportion of Parkinson’s patients with advanced Parkinson’s disease, the referral process, and the clinical features used to characterize advanced Parkinson’s disease are not well delineated. The primary objective of this observational study was to evaluate the proportion of Parkinson’s patients identified as advanced patients according to physician’s judgment in all participating movement disorder centers across the study. Here we evaluate the Hungarian subset of the participating patients. The study was conducted in a cross-sectional, non-interventional, multi-country, multi-center format in 18 countries. Data were collected during a single patient visit. Current Parkinson’s disease status was assessed with Unified Parkinson’s Disease Rating Scale (UPDRS) parts II, III, IV, and V (modified Hoehn and Yahr staging). Non-motor symptoms were assessed using the PD Non-motor Symptoms Scale (NMSS); quality of life was assessed with the PD 8-item Quality-of-Life Questionnaire (PDQ-8). Parkinson’s disease was classified as advanced versus non-advanced based on physician assessment and on questions developed by the Delphi method. Overall, 2627 patients with Parkinson’s disease from 126 sites were documented. In Hungary, 100 patients with Parkinson’s disease were documented in four movement disorder centers, and, according to the physician assessment, 50% of these patients had advanced Parkinson’s disease. Their mean scores showed significantly higher impairment in those with, versus without advanced Parkinson’s disease: UPDRS II (14.1 vs. 9.2), UPDRS IV Q32 (1.1 vs. 0.0) and Q39 (1.1 vs. 0.5), UPDRS V (2.8 vs. 2.0) and PDQ-8 (29.1 vs. 18.9). Physicians in Hungarian movement disorder centers assessed that half of the Parkinson’s patients had advanced disease, with worse motor and non-motor symptom severity and worse QoL than those without advanced Parkinson’s disease. Despite being classified as eligible for invasive/device-aided treatment, that treatment had not been initiated in 25% of these patients.]
MARCH 30, 2020
[Diseases with peripheral motor symptoms are a rare, but important subgroup of the all peripheral neuropathies, radiculopathies and neuronopathies. In these mostly progressive neuropathies, the clinical features include pure motor symptoms with weakness and wasting of the striated muscles. The differentiation of these diseases is frequently a challenge for qualified clinical neurologists. A careful history taking, the disease time course, the findings of routine clinical physical examination and the electrophysiological studies are all necessary in the diagnostic procedure. The aim of this publication is to overview the clinical characteristics of the pure motor peripheral neuropathies, to consider the diagnostic steps and the differential diagnosis, and finally to summarize the treatment options. ]
JULY 30, 2020
[Objective – Conflicting theoretical models exist regarding the mechanism related to the ability of the Jendrassik maneuver to reinforce reflex parameters. Our objective was to investigate if vigorous handgrip would induce changes in recurrent inhibition of soleus motoneurons. Method – Soleus H reflex was evoked by stimulating the tibial nerve at rest and during bilateral vigorous handgrip, alternating single (H1) and paired stimulation (H2). At paired stimulation we used interstimulus intervals of 10, 15, 20 and 25 ms and supramaximal test stimulus. H1- and H2-wave amplitudes were expressed as percentage of maximal M-wave amplitude. Conditioned H2 wave maximal (H2max) and minimal (H2) amplitudes evoked at rest and expressed as a percentage of the unconditioned H1max amplitude were compared with the corresponding values obtained during handgrip by means of paired Student test and Bonferroni correction. Subjects – At the study participated 28 healthy volunteers. Results – The H1max/Mmax × 100 values obtained during handgrip (37.5±10.1) were significantly higher than those obtained at rest (27.1±7.4). The H2max/H1max × 100-values obtained at paired stimulation were significantly higher during handgrip than at rest, while no significant difference was found between the H2/H1max × 100-values obtained during handgrip and at rest respectively. Discussion – The H2max/H1max is determined by both the excitability of the motoneurons and the recurrent inhibition elicited by the conditioning stimulus, while H2/H1max indicates only the level of recurrent inhibition. According to our results the Renshaw cells retain their inhibitory effect on the soleus alpha motoneurons during remote muscle contraction. Conclusion – Soleus H reflex enhancement during Jendrassik maneuver is not due to decrease of recurrent inhibition. ]
NOVEMBER 20, 2015
[Background – The recently published “EarlyStim” study demonstrated that deep brain stimulation (DBS) for the treatment of Parkinson’s disease (PD) with early fluctuations is superior to the optimal pharmacological treatment in improving the quality of life and motor symptoms, and preserving sociocultural position. Our retrospective investigation aimed to evaluate if DBS therapy was able to preserve the working capabilities of our patients. Methods – We reviewed the data of 39 young (<60 years-old) PD patients who underwent subthalamic DBS implantation at University of Pécs and had at least two years follow-up. Patients were categorized into two groups based on their working capabilities: Patients with active job (“Job+” group, n=15) and retired patients (without active job, “Job-” group, n=24). Severity of motor symptoms (UPDRS part 3), quality of life (EQ-5D) and presence of active job were evaluated one and two years after the operation. Results – As far as the severity of motor symptoms were concerned, similar (approximately 50%) improvement was achieved in both groups. However, the postoperative quality of life was significantly better in the Job+ group. Majority (12/15, 80%) of Job+ group members were able to preserve their job two years after the operation. However, only a minimal portion (1/24, 4.2%) of the Job- group members was able to return to the world of active employees (p<0.01, McNemar test). Conclusion – Although our retrospective study has several limitations, our results fit well with the conclusions of “EarlyStim” study. Both of them suggest that with optimal timing of DBS implantation we may preserve the working capabilities of our patients.]
SEPTEMBER 30, 2018
[The revolutionary progress of research in neuroimmunology has led to the introduction of disease modifying therapies in multiple sclerosis at the end of the last century. The International Panel on Diagnosis of Multiple Sclerosis originally proposed the 2001 McDonald criteria to facilitate the diagnosis of MS in patients with the first objective neurological symptom(s) suggesting demyelinating event, when magnetic resonance imaging is integrated with clinical and other paraclinical diagnostic methods. New terms have been introduced to substitute clinical information by MRI: dissemination in space - indicating a multifocal central demyelinating process and dissemination in time - indicating the development of new CNS lesions over time. The criteria for diagnosis of Multiple Sclerosis have continuously evolved, they were modified in 2005 and 2010 allowing for an earlier and more accurate diagnosis of MS over time, and they provided the most up-to-date guidance for clinicians and researchers. The last recommended revisions relied entirely on available evidence, and not on expert opinion thereby reducing the risk of the misdiagnosis. The 2017 McDonald criteria continue to apply primarily to patients experiencing a typical, clinically isolated syndrome. In this review, we provide an overview of the recent 2017 revisions to the criteria of dissemination in space and time with the importance of the presence of CSF-specific oligoclonal bands; keeping fully in mind that there is no better explanation for symptoms than diagnosis of MS. In the future, validation of the 2017 McDonald criteria will be needed in diverse populations. Further investigations are required on the value of new MRI approaches, on optic nerve involvement, on evoked potential and optical coherence tomography, in order to assess their possible contribution to diagnostic criteria.]
JANUARY 30, 2016
Background and purpose – There is growing evidence for the viral origin of the Bell’s facial palsy, vestibular neuritis and sudden sensorineural hearing loss, however their exact pathophysiology is still unknown. We investigated the possibility of brainstem infections following peripheral viral inoculations in rats. Methods – Pseudorabies virus, a commonly used neurotropic viral retrograde tracer was injected into the nasolabial region of rats. Five and 6 days after injections, infected brainstem nuclei were demonstrated by immunohistochemical techniques. Results – Infected neurons were found in the motor facial, the medial vestibular, and the sensory trigeminal nuclei, as well as in the medial nucleus of the trapezoid body. Conclusion – Pseudorabies virus infects auditory and vestibular sensory neurons in the brainstem through facial inoculation. The possible routes of infections: 1. trans-synaptic spread constituted by facio-vestibular anastomoses: primarily infected motor facial neuron infects neurons in the medial vestibular nucleus, 2. via trigeminal sensory nerves: the sensory trigeminal complex innervated by GABAergic medial vestibular neurons, and 3. one bisynaptical route: infected facial motoneurons may receive indirect input from the medial vestibular nucleus and the trapezoid body via connecting neurons in the sensory trigeminal complex. We may assume that latent infections of these areas may precede the infections of the peripheral organs and the reactivation of the virus exerts the symptoms.
MARCH 30, 2019
Objective - to investigate the neurophysiological basis of secondary generalization of partial epileptic seizures. Patients and methods - inter-ictal, resting-state EEG functional connectivity (EEGfC) was evaluated and compared: patients with exclusively simple partial seizures (sp group) were compared to patients with simple partial and secondary generalized seizures (spsg group); patients with exclusively complex partial seizures (cp group) were compared to patients with cp and secondary generalized seizures (cpsg group); the collapsed sp+cp group (spcp) was compared to those who had exclusively secondary generalized seizures (sg group). EEGfC was computed from 21-channel waking EEG. 3 minutes of waking EEG background activity was analyzed by the LORETA Source Correlation (LSC) software. Current source density time series were computed for 23 pre-defined cortical regions (ROI) in each hemisphere, for the 1-25 Hz very narrow bands (1 Hz bandwidth). Thereafter Pearson correlation coefficients were calculated between all pairs of ROI time series in the same hemisphere. Z-scored correlation coefficients were compared at the group level (t-tests and correction for multiple comparisons by local false discovery rate, FDR). Results - Statistically significant (corrected p<0.05) EEGfC differences emerged at specific frequencies (spsg > sg; cpsg > cp), and at many frequencies (sg > spcp). The findings indicated increased coupling between motor cortices and several non-motor areas in patients with partial and sg seizures as compared to patients with partial seizures and no sg seizures. Further findings suggested increased coupling between medial parietal-occipital areas (structural core of the cortex) and lateral hemispheric areas. Conclusion - increased inter-ictal EEGfC is associated with habitual occurrence of secondary generalized seizures.
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