S150. Detection of upper motor neuron impairment in ALS with central motor conduction time

Abstracts / Clinical Neurophysiology 129 (2018) e142–e212

tract, in certain clinical conditions, it is of diagnostic value and it can also be used as a prognostic marker in some of neurological conditions, such as myelopathy and multiple sclerosis (MS). The pathophysiology of pyramidal dysfunction in stroke is quite different from that in myelopathy because the pyramidal weakness of stroke patients may improve while the original lesions remain unchanged. The aim of this study is to investigate the role of CMCT for acute ischemic stroke patients and discuss which clinical and MRI characteristics correlate with the prolongation of CMCT. Methods: Totally 94 patients with acute ischemic stroke (age: 67.13 ± 10.73 y/o; M%: 69.15%) were enrolled in this study. They all received evaluation of stroke risk factors, clinical course record (eg, TIA, Clinical Progression), neurologic examination (include muscle power on MRC score, NIHSS and mRS on admission), CMCT exam (CMCT(+) indicates CMCT prolongation), cranial MRI exam, data analysis and then were classified as clinical‘‘New Stroke”,‘‘Ever Stroke”,‘‘Any lesions on MRI”,‘‘New Pyramidal lesions on MRI”, and‘‘Ever Pyramidal lesions on MRI”groups. Results: The CMCT (+) group has significantly more cases in the ‘‘New Stroke”, ‘‘TIA”, ‘‘Progression”, ‘‘Any Lesions”, ‘‘New Pyramidal lesions on MRI”, ‘‘Ever Pyramidal lesions on MRI” and ‘‘MP < 5” than the CMCT ( ) group. The CMCT (+) group has significantly higher value of ‘‘Muscle power on MRC”,”NIHSS” and ”mRS” on admission than the CMCT ( ) groups. After ANCOVA adjustment, the CMCT (+) group has significantly more cases only in ‘‘New Pyramidal lesions on MRI” and ‘‘Clinical Progression” groups (Table 1). Conclusion: CMCT is both of diagnostic value of acute ischemic stroke with new pyramidal lesions and predictive value of stroke progression. doi:10.1016/j.clinph.2018.04.508

S149. Improved bimanual control in elderly after motor cortex stimulation—Asif Jamil 1,*, Koen Cuypers 1, Miya Kato Rand 2, Michael A. Nitsche 2, Raf Meesen 1 (1 Belgium, 2 Germany) ⇑

Presenting author.

Introduction: Accompanying the natural advancing of age is a decline in cognitive and motor functions, which may be the result of altered neuroplasticity, due to changes in synaptic function and neurotransmission. Successful performance of routine, but complex motor tasks such as bimanual movements may require optimal synchronization of motor cortical areas, which decline with ageing. On the other hand, recent work has shown that transcranial direct current stimulation (tDCS) may be a useful tool to restitute these altered mechanisms, and improve performance of motor skills. Presently, we address the question of identifying physiological markers of agerelated differences during acquisition of new bimanual motor control tasks, based on induced oscillatory changes, using EEG. Second, we assess whether performance of complex bimanual skills can be improved in the elderly using tDCS. Methods: Experiment 1: 43 healthy subjects (21 elderly) performed the bimanual tracking task (BTT), which is a complex task requiring multiple cognitive domains, as well as the skilled use of in-phase and anti-phase movements, at various frequencies. Three blocks of the task were performed (180 total trials) while EEG was recorded to measure task-induced power changes. Experiment 2: An additional 40 subjects (20 elderly) were recruited for evaluating whether right M1 anodal tDCS (1.0 mA, 20 min) may improve performance in the task, particularly in the non-dominant left hand. The study was double-blinded, sham-controlled, and employed a randomized crossover design in order to assess tDCS-induced performance and

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task-induced synchronization differences between young and elderly groups. Results: Experiment 1: Overall task performance in younger subjects was more accurate than in elderly. Younger subjects showed significantly stronger desynchronization in the mu and beta band, whereas older subjects showed greater gamma band activity in motor cortical areas. In addition, these patterns were also found to correlate inter-individually with accurate performance in the task. Experiment 2: ANOVA revealed a main effect of stimulation, which was significant between active and sham tDCS conditions in the elderly but not in young. Further exploratory analyses revealed significant improvements in both left and right hand coordination in active stimulation conditions for both groups of subjects, with the greatest improvement found in left-hand dominant motor movements in the elderly group. Conclusion: We show that both task-induced oscillatory synchronization and inter-limb kinematics underlying bimanual motor coordination are different between the young and elderly. Further, a single session of tDCS applied to the motor cortex could significantly improve bimanual performance in the elderly. Although further studies are needed to optimize tDCS parameters for enhanced and prolonged effects, tDCS may be a viable tool in restituting the learning of complex motor functions in the aging or other vulnerable populations. doi:10.1016/j.clinph.2018.04.509

S150. Detection of upper motor neuron impairment in ALS with central motor conduction time—Takenobu Murakami *, Ryo Tokimura, Setsu Nakatani-Enomoto, Hiroyuki Enomoto, Yoshikazu Ugawa (Japan) ⇑

Presenting author.

Introduction: Detection of both upper and lower motor neuron impairments is essential for making a diagnosis of amyotrophic lateral sclerosis (ALS). Although electrophysiological findings identifying lower motor neuron damage have been established, there are few useful objective biomarkers for upper motor neuron impairment. Here, we retrospectively investigated the utility of the central motor conduction time (CMCT) for the detection of upper motor neuron impairment in patients with ALS. Methods: Fifty-five patients were diagnosed as ALS from 2007 to 2017 in our hospital. Forty-five ALS patients without any signal changes in the pyramidal tracts on magnetic resonance images and 10 healthy controls participated in this study. Electromyograms were recorded from the first dorsal interosseous and tibialis anterior muscles. Transcranial magnetic stimulation and magnetic motor root stimulation were performed to measure cortical and root latencies and obtained the CMCT. ALS patients were classified into two subgroups; positive and negative Babinski’s sign. The cortical and motor root latencies and CMCT were compared between two subgroups. Finally, we calculated the rates of ALS patients with abnormally prolonged CMCT (longer than mean +2 standard deviation of normal values). Results: Cortical latency, motor root latency and CMCT were significantly longer in ALS group than the control group. There were no differences in the latencies and CMCT between the two subgroups of ALS patients. The CMCT was abnormally prolonged in 60% of ALS patients with positive Babinski’s sign and 50% of those with negative Babinski’s sign, respectively. Conclusion: The CMCT is useful for detecting upper motor neuron impairment in patients with ALS without any clinical pyramidal

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Abstracts / Clinical Neurophysiology 129 (2018) e142–e212

signs. CMCT can pave the way for finding upper motor neuron impairment masked by lower motor neuron damage in ALS patients.

S152. Modulation of motion perception by bilateral MT/V5 tDCS stimulation—Kuan-Lin Lai *, David M. Niddam, Jong-Ling Fuh, Kwong-Kum Liao, Chi-Hung Juan, Shuu-Jiun Wang (Taiwan)

doi:10.1016/j.clinph.2018.04.510 ⇑

S151. Assessing lower limb cortical function with threshold tracking transcranial magnetic stimulation—Thanuja Dharmadasa *, Jose M. Matamala, James Howells, Steve Vucic, Matthew Kiernan (Australia) ⇑

Presenting author.

Introduction: Transcranial magnetic stimulation (TMS) is a useful, non-invasive tool that can explore the functional integrity of the primary motor cortex and corticomotor pathways. Although the application of TMS has rapidly increased in the last decade using upper limb muscle targets, there remains a relative paucity of lower limb studies. Additionally, the paired-pulse TMS paradigms that have been applied to explore lower limb cortical parameters have shown significant variability in motor evoked potential (MEP) amplitudes, questioning the reliability and clinical utility of this technique. Threshold tracking TMS (TT-TMS) was recently developed to overcome such methodological problems, but this protocol has been limited to upper limb studies. Importantly, the inherent differences in upper and lower limb normal cortical function and the differing pattern of disease in lower limb predominant neurological disorders highlights the need for a more robust understanding of lower limb corticomotoneuronal function. Thus, the aim of the present study was to employ TT-TMS to establish lower limb cortical parameters and to investigate side-to-side differences to determine laterality of normal cortical function. Methods: Studies were performed in 40 healthy participants recording from the tibialis anterior muscle bilaterally. Three common coil choices (90 mm circular coil, 70 mm figure-8 coil, 110 mm double cone coil) were explored. Single-pulse TMS, pairedpulse TT-TMS and nerve conduction studies were performed. Results: The double cone coil had the greatest efficacy, generating a significantly lower resting motor threshold than the circular (p = 0.04) or figure-8 (p = 0.01) coils. Paired-pulse TT-TMS generated an averaged short interval intracortical inhibition of 11.3 ± 1.2%, with an averaged intracortical facilitation of 8.5 ± 1.1%. Central motor conduction time (CMCT) was 8.9 ± 0. 6 ms.There were no differences between dominant and non-dominant sides for all single (RMT, MEP latency, MEP amplitude, MEP/CMAP ratio, CSP and CMCT) and paired-pulse TT-TMS parameters (peak SICI 1 ms, peak SICI 3 ms, averaged SICI and ICF). Similarly, peripheral measures of nerve function were not significantly different between the dominant and nondominant hemispheres for all measures tested. Conclusion: This study successfully assessed cortical excitability and corticospinal pathways from the lower limbs using TT-TMS, establishing normative data, symmetry of normal cortical function, and validating the double cone coil for future studies. These findings can now be applied to explore further aspects of lower limb physiology and used for the clinical interpretation of motor cortical dysfunction across a range of neurological diseases. Together with previously established upper limb TT-TMS, this study will now inevitably allow for a more comprehensive evaluation of normal neuronal processes and patterns of disease across a larger area of cortical representation. doi:10.1016/j.clinph.2018.04.511

Presenting author.

Introduction: Transcranial direct current stimulation (tDCS) is able to modulate the cortical excitability underneath the stimulating electrode, hence altering its function. Previous studies have demonstrated that tDCS over middle temporal visual area (MT/V5), with the reference electrode over the frontal or central cortex, was able to interfere the correct answer rate to random dot motion (RDM) test. Nevertheless, whether the effect came from the active electrode (i.e. over unilateral MT/V5) or the reference electrode remained elusive. In this study, we applied tDCS stimulation, either anodal or cathodal, over bilateral MT/V5, with referenced to a common extra-cranial electrode over chin, to further elucidate if the effect is derived from MT/V5 modulation. Methods: Fifteen subjects (M/F: 6/9, mean age: 30.0 ± 9.4 years) participated in this study. Before tDCS treatment, a baseline simple random dot motion test (sRDM) was performed. Subjects were seated comfortably in a semidarkened room at a distance of 75 cm from the monitor. A forced-choice motion-direction discrimination task was used. Subjects had to report the direction (left or right) of the coherent motion dots presenting in the center of the monitor, in a 10o  10o window. After a learning session that all subjects were able to answer correctly approximately 75%, 50 trials were tested to calculate the accurate rate. Bilateral MT/V5 tDCS stimulation, either anodal or cathodal, was then applied, with the reference electrode placed over chin. The current was applied for 20 min with an intensity of 2.0 mA. After tDCS treatment, the sRDM was repeated for 3 times (10 min apart each other). Results: After anodal tDCS treatment, a transient improved accuracy of sRDM was observed. The accuracy changed from 0.77 ± 0.11 (pre) to 0.81 ± 0.11 (post_1), 0.78 ± 0.12 (post_2), 0.72 ± 0.13 (post_3), p = 0.019, Friedman test. Post-hoc Wilcoxon signed-rank test showed that the difference came from pre vs. post_1 (p = 0.042), post_1 vs. post_3 (p = 0.027), and post_2 vs. post_3 (p = 0.042). Alteration of sRDM accuracy was not observed after bilateral MT/V5 cathodal tDCS stimulation. Conclusion: Bilateral MT/V5 anodal tDCS stimulation is able to modulate the function in motion perception. Our study provided evidence that tDCS may exert its modulatory effects through MT/V5 directly. doi:10.1016/j.clinph.2018.04.512

S153. Changes of triad-conditioning facilitation in various neurological disorders—Ritsuko Hanajima 1,*, Stefan Groiss 2, Yasuo Terao 1, Setsu Nakatani-Enomoto 1, Yuichiro Shirota 1, Takahiro Shimizu 1, Masashi Hamada 1, Hideyuki Masumoto 1, Yoshikazu Ugawa 1 (1 Japan, 2 Germany) ⇑

Presenting author.

Introduction: Recently, we have reported a triad-conditioning transcranial magnetic stimulation technique (TMS). In this technique, the intercortical facilitation is induced by 40 Hz (interval 25 ms) triad-conditioning stimulation in healthy volunteers, which may reflect the intrinsic rhythm of the primary motor cortex (M1). We used this method to study some changes in M1 in various neurological disorders. Methods: Participants were 7 cortical myoclonus, 13 Parkinson’s disease (PD), 13 amyotrophic lateral sclerosis (ALS), 5 focal dystonia