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PTMS70 Hemispheric asymmetry resting motor threshold as the indicator of brain dysfunction
14th ECCN / 4th ICTMS/DCS of stimulation, as indicated by a reduction of peak-to-peak MEPs amplitudes. This result was replied in a subgroup of male stutterers (considering that stuttering could affect principally males) when compared to male normal speakers: again, weaker neural responses were present in the left regions of primary motor cortex. This was evident for every intensity of stimulation and, with a better statistical significance, when stimulating at 150% of RMT. Conclusions: Present findings provide reinforcing evidence that DS may be considered as a general motor deficit, involving motor speech-related structures in a not exclusive way. Moreover, present findings suggest that DS could be related to a left hemisphere hypo-activation, speculatively compensated by the right hemisphere. Finally, the present data and protocol may be useful for diagnosis of DS subtypes that may benefit from specific pharmacological treatment, targeting the general level of cortical excitability. PTMS67 Effects of repetitive transcranial magnetic stimulation on experimental hyperalgesia in healthy subjects P. Sacco1 , M. Prior2 , H. Poole2 , T. Nurmikko1 1 University of Liverpool, Liverpool, United Kingdom, 2 John Moores University, Liverpool, United Kingdom Objective: We investigated the analgesic effects of repetitive transcranial magnetic stimulation (rTMS) at different cortical sites on hyperalgesia induced using topical capsaicin. Methods: 14 healthy subjects had capsaicin cream (0.075% w/w) applied to 16 cm2 of the medial aspect of the right wrist (60 min) on 4 separate occasions over 6 weeks. rTMS (10 Hz for 10s/min = 2000 stimuli @ 90% resting motor threshold of first dorsal interosseus muscle) was applied to the optimum site for right hand (M1), left dorsolateral prefrontal (PF) and occipital midline (OCC) in a pseudo-randomised order. Thermal and mechanical perception and pain thresholds were determined using standardised quantitative sensory testing methods at the capsaicin site. Subjective responses to thermal stimuli (pain score on a numerical rating scale) from 2.5ºC to +2.5ºC of the individualised heat pain threshold (HPT) resulted in a hyperalgesia curve. Sensory testing took place prior to capsaicin application (PRE-CAP), after 30 min of capsaicin (POST-CAP) and following rTMS (30 min= POST-TMS). Values are means with comparisons using repeated measures ANOVA and post-hoc paired student T tests (p < 0.05). Results: Capsaicin application resulted in substantial changes in thermal (but not mechanical) sensitivity to both heat and cold (eg. HPT PRECAP = 43.6ºC to POST-CAP = 36.7ºC (p < 0.001) with no differences between groups pre-rTMS. POST-TMS HPT showed no changes for any of the treatment groups, however the pain scores for the hyperalgesia curve were significantly lower for M1 vs OCC ( 24.7%, p < 0.001) and for M1 vs PF ( 18.3%, p < 0.02). Conclusion: rTMS over the primary motor cortex results in a significant analgesic effect compared to other cortical areas. PTMS68 Navigated transcranial magnetic stimulation mapping of the primary motor cortex in patients with complex regional pain syndrome: a pilot study G. Mbizvo1 , A. Powell1 , P. Sacco1 , T. Nurmikko1 Faculty of Health and Life Sciences, University of Liverpool, Liverpool, United Kingdom 1
Introduction: Changes in cortical representation of the affected limb in Complex Regional Pain Syndrome (CRPS) may play a significant role in the disease pathophysiology. Objectives: To use navigated transcranial magnetic stimulation (TMS) to map cortical representation of the affected & unaffected hands in CRPS patients. Methods: 5 CRPS patients & 9 healthy controls underwent MRI-guided single-pulse TMS to map representations of the left & right first dorsal interosseous muscles. The identified “motor hot spot” acted as the centre for a superimposed target grid for stimuli. Each 5 mm2 box in the grid was stimulated 2 & 4 times in patients & controls, respectively, at 5 s intervals. Stimuli were applied at 110% of the resting motor threshold with the coil perpendicular to the central sulcus. The cut-off for a positive response was 10% of the maximum average MEP. Main outcome was map size (cm2 ) compared within & between groups using paired & unpaired t-tests, respectively (p < 0.05). The size & shape of individual maps was
S199 also scrutinised. Map volume (cm2 mV) & centre-position (mm, x- & yhead coordinate axes) were additional measurements. Results: 3 patients with the most severe clinical features also had the most asymmetric maps in terms of size & shape. There was marked variability in map size in the affected hemisphere (mean size 4.6 cm2± 2.7 SD, 95% confidence interval 1.3 7.9). Map-centre position for the affected hemisphere was between 3 5 mm more lateral from the midline compared to all other hemispheres, and the volume between 15.8 & 48.4 cm2 mV smaller. Group-wise comparisons were not significant. 1 patient reported an exacerbation of their pain & developed a migraine attack. Conclusions: This pilot study adds to the emerging evidence of the presence of cortical reorganisation in patients with CRPS. Further evaluation of the changes may be warranted as motor dysfunction is a significant clinical problem in the majority of CRPS patients. PTMS69 Predictive value for walking ability of motor evoked potentials and total motor score in incomplete tetraplegia M. Schubert1 , J. Petersen2 , A. Curt1 1 Spinal Cord Injury Center, University Hospital Balgrist, Zuerich, Switzerland, 2 Department of Neurology, University Hospital Zuerich, Zuerich, Switzerland Introduction: Electrophysiological recordings of motor evoked potentials from anterior tibial muscle (tMEP) and total segmental motor score (tMS) according to ASIA (American Spinal Injury Association) standard are both significant for predicting functional outcome of walking capacity following spinal cord injury (SCI). Objectives: To determine if initial assessment of total segmental motor score (tMS) or motor evoked potentials from anterior tibial muscle (tMEP) or a combination of both allow better prediction of walking capacity at 6 or 12 months after SCI; to find discriminative cut-off values for tMS and tMEP for prediction. Methods: European Multicenter Study of Human Spinal Cord Injury (www.emsci.org); assessments at 2 4 weeks after incomplete cervical SCI were obtained of tMS and tMEP and compared to walking ability at 6 or 12 months. Receiver operating characteristic (ROC) curves were constructed to discriminate between patients with and without walking capacity. Best discriminative values for tMS and tMEP were derived to calculate positive predictive values (PPV) and negative predictive values (NPV) for both parameters. Results: Seventy-five of 119 patients reached walking ability; predicted probability was excellent in discriminating non-walking from walking patients (AUC for tMS: 0.92; AUC for tMEP: 0.82). Best discriminative values determined from ROC curves were 50 points for tMS and 0.2mV for tMEP. The prediction of walking ability reached a PPV of 93% for tMS > 50 and PPV of 90% for tMEP >0.2 mV, respectively, and a NPV of 68% for tMS and of 68% for tMEP. Combining the tMS and tMEP did not increase PPV (90%) while NPV clearly increased to 85%. Conclusion: tMS and tMEP are equally valuable to predict walking capacity in incomplete tetraplegia. While PPV was comparable for individual and combined assessment of tMS and tMEP, NPV was clearly improved by their combined assessment. PTMS70 Hemispheric asymmetry resting motor threshold as the indicator of brain dysfunction A. Solichien1 1 Duren Sawit Hospital, Jakarta, Indonesia Background: Resting motor threshold (r MT) is a basic unit of trans cranial magnetic stimulation (TMS) dosing. While measuring rMT, our observation show there is different between left and right hemisphere especially in the extreme condition such as stroke and other dysfunction. The AIM: of our study is to determine whether absolute resultant rMT could be used as one of the parameter brain dysfunction. Methods: We analyzed 256 respondents (average age 54.5 and 53.6% are female) without and with different clinical diagnostic and measure resting motor threshold with traditional methods by finding a threshold of visible thumb and finger movement. For each category of clinical diagnostic, we analyzed the imbalance resting motor threshold. For control also included 45 students and staff from Faculty of Public Health, University of Indonesia
S200 Result: Mean of absolute resultant rMT total 10.1, and there was significant difference between groups (F = 17.07, p-value = 0.000). Using post hoc test, we tried to compare different diagnostics with respondents with no complain of symptom as reference group. The result showed that CVD or stroke was significantly different compared to respondents without complain symptoms (rMT of CVD = 22.91 compared to rMT of normal group = 4.98). Conclusion: This study show that only stroke is significantly difference among other clinical diagnostic groups, although qualitatively we can see slightly difference rMT among vertigo, Parkinson’s disease, insomnia, hyperventilation and depression. Further analysis can be conducted using more robust design. PTMS71 Evaluation of the effect of transcranial electrical stimulation on motor learning using fMRI C. Saiote1 , R. Polania1 , K. Rosenberger1 , W. Paulus1 , A. Antal1 1 Department of Clinical Neurophysiology Univ. of Gottingen, Gottingen, Germany Introduction: Several studies have been conducted that show modulation of motor performance or learning when cortical excitability is modulated by transcranial direct current (tDCS) or random noise stimulation (tRNS). However, most of these studies have used only behavioral measurements to assess the effects of stimulation. Objectives: Using simultaneous tDCS or tRNS and functional magnetic resonance imaging (fMRI) the goal of this study is to assess the effects of these stimulation techniques on a motor learning task and its fMRI correlates. Methods: A group of 48 healthy volunteers participated in the study divided into 5 groups according to type of stimulation: sham (n = 10), tDCS anodal (n = 10), tDCS cathodal (n = 10), tRNS high frequency (n = 9) and tRNS low frequency (n = 9). The data acquisition session was performed at 3T and consisted of 3 runs of 10 min each where participants had to perform a visual-motor task with visual feedback. Each run followed a block design with periods of rest of 8 s and task periods of 4 s repeated 50 times. Stimulation was given during the first run with a stimulation intensity of 1 mA. The active electrode was positioned over the left M1 and the reference electrode over the contralateral orbita. Data was analyzed using Tensorial Independent Component Analysis with the software tools available in FSL. A group analysis was carried out comparing each stimulation group with the sham group. For each component, the subject modes resulting from the analyses were used in a general linear model approach to find significant differences between groups. These were then compared with the behavioral results. Results: Several components consistent with the task were identified across groups, including the whole motor network and also the hippocampus, reflecting the learning component of the task. Some of the components were significantly different between stimulation groups, for instance, group analysis of sham, anodal and cathodal groups, yielded components with significant differences in the contrasts anodal>cathodal, anodal>sham and sham>cathodal. Networks with significantly altered connectivity were also found when comparing tRNS high-frequency with sham, but not in the tRNS low-frequency group. Conclusions: We were able to identify online changes in brain networks as a consequence of the type of stimulation that was pronounced at the early phase of learning. Further studies should clarify if different types of learning task can be modulated at the same way and how this effected by the individual learning strategies used by the different subjects.
Poster presentations: TMS meeting poster session PTMS72 A reappraisal of the anatomical landmarks of motor and premotor cortical regions for image-guided brain navigation in TMS practice S.S. Ayache1 , R. Ahdab1 , P. Brugieres1 , J.P. Lefaucheur1 1 EA4391, Universit´ e Paris-Est, Cr´ eteil, France, Dept. of Physiology and Neuroradiology, Hosp Henri Mondor, Cr´ eteil, France Introduction: Image-guided navigation systems dedicated to transcranial magnetic stimulation (TMS) have been recently developed and offered the possibility to visualize the anatomical structures to be stimulated. When guided by magnetic resonance imaging (MRI) data, navigated TMS allows stimulation of well-defined anatomical areas and cortical mapping to be performed. However, mapping requires a perfect knowledge of the anatomical landmarks of the cortical surface, which could be quite variable between subjects. Objective: To study the inter-individual variability of sulci and gyri in the motor and premotor cortical regions using an image-guided navigation system for TMS practice. Methods: Fifty consecutive healthy adult brains (100 hemispheres) extracted from our navigated TMS database were studied. The 3D reconstruction of the brain from morphological MRI data was analyzed to identify the anatomical variants and the most stable structures that could offer reliable markers to perform cortical mapping in neuronavigated TMS practice. Results: We found a remarkable stability of several anatomical structures on the cortical surface (four on the dorsoventral axis and five on the rostrocaudal axis) that could serve as reliable landmarks to define in each subject an individualized anatomical grid dividing the motor cortex into segments. Such segmentation could greatly help in expressing individual results of TMS mapping of the motor and premotor cortical regions and overcome the inter-individual variability of the sulci and gyri. Conclusion: We propose an original and standardized manner to perform motor cortex mapping using an image-guided navigation system for TMS practice, improving the reliability and comparability of individual maps provided by navigated TMS.
Introduction: Changes in cortical representation of the affected limb in Complex Regional Pain Syndrome (CRPS) may play a significant role in the disease pathophysiology. Objectives: To use navigated transcranial magnetic stimulation (TMS) to map cortical representation of the affected & unaffected hands in CRPS patients. Methods: 5 CRPS patients & 9 healthy controls underwent MRI-guided single-pulse TMS to map representations of the left & right first dorsal interosseous muscles. The identified “motor hot spot” acted as the centre for a superimposed target grid for stimuli. Each 5 mm2 box in the grid was stimulated 2 & 4 times in patients & controls, respectively, at 5 s intervals. Stimuli were applied at 110% of the resting motor threshold with the coil perpendicular to the central sulcus. The cut-off for a positive response was 10% of the maximum average MEP. Main outcome was map size (cm2 ) compared within & between groups using paired & unpaired t-tests, respectively (p < 0.05). The size & shape of individual maps was
S199 also scrutinised. Map volume (cm2 mV) & centre-position (mm, x- & yhead coordinate axes) were additional measurements. Results: 3 patients with the most severe clinical features also had the most asymmetric maps in terms of size & shape. There was marked variability in map size in the affected hemisphere (mean size 4.6 cm2± 2.7 SD, 95% confidence interval 1.3 7.9). Map-centre position for the affected hemisphere was between 3 5 mm more lateral from the midline compared to all other hemispheres, and the volume between 15.8 & 48.4 cm2 mV smaller. Group-wise comparisons were not significant. 1 patient reported an exacerbation of their pain & developed a migraine attack. Conclusions: This pilot study adds to the emerging evidence of the presence of cortical reorganisation in patients with CRPS. Further evaluation of the changes may be warranted as motor dysfunction is a significant clinical problem in the majority of CRPS patients. PTMS69 Predictive value for walking ability of motor evoked potentials and total motor score in incomplete tetraplegia M. Schubert1 , J. Petersen2 , A. Curt1 1 Spinal Cord Injury Center, University Hospital Balgrist, Zuerich, Switzerland, 2 Department of Neurology, University Hospital Zuerich, Zuerich, Switzerland Introduction: Electrophysiological recordings of motor evoked potentials from anterior tibial muscle (tMEP) and total segmental motor score (tMS) according to ASIA (American Spinal Injury Association) standard are both significant for predicting functional outcome of walking capacity following spinal cord injury (SCI). Objectives: To determine if initial assessment of total segmental motor score (tMS) or motor evoked potentials from anterior tibial muscle (tMEP) or a combination of both allow better prediction of walking capacity at 6 or 12 months after SCI; to find discriminative cut-off values for tMS and tMEP for prediction. Methods: European Multicenter Study of Human Spinal Cord Injury (www.emsci.org); assessments at 2 4 weeks after incomplete cervical SCI were obtained of tMS and tMEP and compared to walking ability at 6 or 12 months. Receiver operating characteristic (ROC) curves were constructed to discriminate between patients with and without walking capacity. Best discriminative values for tMS and tMEP were derived to calculate positive predictive values (PPV) and negative predictive values (NPV) for both parameters. Results: Seventy-five of 119 patients reached walking ability; predicted probability was excellent in discriminating non-walking from walking patients (AUC for tMS: 0.92; AUC for tMEP: 0.82). Best discriminative values determined from ROC curves were 50 points for tMS and 0.2mV for tMEP. The prediction of walking ability reached a PPV of 93% for tMS > 50 and PPV of 90% for tMEP >0.2 mV, respectively, and a NPV of 68% for tMS and of 68% for tMEP. Combining the tMS and tMEP did not increase PPV (90%) while NPV clearly increased to 85%. Conclusion: tMS and tMEP are equally valuable to predict walking capacity in incomplete tetraplegia. While PPV was comparable for individual and combined assessment of tMS and tMEP, NPV was clearly improved by their combined assessment. PTMS70 Hemispheric asymmetry resting motor threshold as the indicator of brain dysfunction A. Solichien1 1 Duren Sawit Hospital, Jakarta, Indonesia Background: Resting motor threshold (r MT) is a basic unit of trans cranial magnetic stimulation (TMS) dosing. While measuring rMT, our observation show there is different between left and right hemisphere especially in the extreme condition such as stroke and other dysfunction. The AIM: of our study is to determine whether absolute resultant rMT could be used as one of the parameter brain dysfunction. Methods: We analyzed 256 respondents (average age 54.5 and 53.6% are female) without and with different clinical diagnostic and measure resting motor threshold with traditional methods by finding a threshold of visible thumb and finger movement. For each category of clinical diagnostic, we analyzed the imbalance resting motor threshold. For control also included 45 students and staff from Faculty of Public Health, University of Indonesia
S200 Result: Mean of absolute resultant rMT total 10.1, and there was significant difference between groups (F = 17.07, p-value = 0.000). Using post hoc test, we tried to compare different diagnostics with respondents with no complain of symptom as reference group. The result showed that CVD or stroke was significantly different compared to respondents without complain symptoms (rMT of CVD = 22.91 compared to rMT of normal group = 4.98). Conclusion: This study show that only stroke is significantly difference among other clinical diagnostic groups, although qualitatively we can see slightly difference rMT among vertigo, Parkinson’s disease, insomnia, hyperventilation and depression. Further analysis can be conducted using more robust design. PTMS71 Evaluation of the effect of transcranial electrical stimulation on motor learning using fMRI C. Saiote1 , R. Polania1 , K. Rosenberger1 , W. Paulus1 , A. Antal1 1 Department of Clinical Neurophysiology Univ. of Gottingen, Gottingen, Germany Introduction: Several studies have been conducted that show modulation of motor performance or learning when cortical excitability is modulated by transcranial direct current (tDCS) or random noise stimulation (tRNS). However, most of these studies have used only behavioral measurements to assess the effects of stimulation. Objectives: Using simultaneous tDCS or tRNS and functional magnetic resonance imaging (fMRI) the goal of this study is to assess the effects of these stimulation techniques on a motor learning task and its fMRI correlates. Methods: A group of 48 healthy volunteers participated in the study divided into 5 groups according to type of stimulation: sham (n = 10), tDCS anodal (n = 10), tDCS cathodal (n = 10), tRNS high frequency (n = 9) and tRNS low frequency (n = 9). The data acquisition session was performed at 3T and consisted of 3 runs of 10 min each where participants had to perform a visual-motor task with visual feedback. Each run followed a block design with periods of rest of 8 s and task periods of 4 s repeated 50 times. Stimulation was given during the first run with a stimulation intensity of 1 mA. The active electrode was positioned over the left M1 and the reference electrode over the contralateral orbita. Data was analyzed using Tensorial Independent Component Analysis with the software tools available in FSL. A group analysis was carried out comparing each stimulation group with the sham group. For each component, the subject modes resulting from the analyses were used in a general linear model approach to find significant differences between groups. These were then compared with the behavioral results. Results: Several components consistent with the task were identified across groups, including the whole motor network and also the hippocampus, reflecting the learning component of the task. Some of the components were significantly different between stimulation groups, for instance, group analysis of sham, anodal and cathodal groups, yielded components with significant differences in the contrasts anodal>cathodal, anodal>sham and sham>cathodal. Networks with significantly altered connectivity were also found when comparing tRNS high-frequency with sham, but not in the tRNS low-frequency group. Conclusions: We were able to identify online changes in brain networks as a consequence of the type of stimulation that was pronounced at the early phase of learning. Further studies should clarify if different types of learning task can be modulated at the same way and how this effected by the individual learning strategies used by the different subjects.
Poster presentations: TMS meeting poster session PTMS72 A reappraisal of the anatomical landmarks of motor and premotor cortical regions for image-guided brain navigation in TMS practice S.S. Ayache1 , R. Ahdab1 , P. Brugieres1 , J.P. Lefaucheur1 1 EA4391, Universit´ e Paris-Est, Cr´ eteil, France, Dept. of Physiology and Neuroradiology, Hosp Henri Mondor, Cr´ eteil, France Introduction: Image-guided navigation systems dedicated to transcranial magnetic stimulation (TMS) have been recently developed and offered the possibility to visualize the anatomical structures to be stimulated. When guided by magnetic resonance imaging (MRI) data, navigated TMS allows stimulation of well-defined anatomical areas and cortical mapping to be performed. However, mapping requires a perfect knowledge of the anatomical landmarks of the cortical surface, which could be quite variable between subjects. Objective: To study the inter-individual variability of sulci and gyri in the motor and premotor cortical regions using an image-guided navigation system for TMS practice. Methods: Fifty consecutive healthy adult brains (100 hemispheres) extracted from our navigated TMS database were studied. The 3D reconstruction of the brain from morphological MRI data was analyzed to identify the anatomical variants and the most stable structures that could offer reliable markers to perform cortical mapping in neuronavigated TMS practice. Results: We found a remarkable stability of several anatomical structures on the cortical surface (four on the dorsoventral axis and five on the rostrocaudal axis) that could serve as reliable landmarks to define in each subject an individualized anatomical grid dividing the motor cortex into segments. Such segmentation could greatly help in expressing individual results of TMS mapping of the motor and premotor cortical regions and overcome the inter-individual variability of the sulci and gyri. Conclusion: We propose an original and standardized manner to perform motor cortex mapping using an image-guided navigation system for TMS practice, improving the reliability and comparability of individual maps provided by navigated TMS.