Person: Vial Undurraga, Felipe
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Vial Undurraga
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Felipe
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Publication KCNN2 Mutation in Pediatric Tremor Myoclonus Dystonia Syndrome with Electrophysiological Evaluation(2022) Lavenstein, Bennett; McGurrin, Patrick; Attaripour, Sanaz; Vial Undurraga, Felipe; Hallett, MarkBackground: Here we combine clinical, electrophysiological, and genetic findings to phenotype an unusual childhood movement disorder in a patient with a rare form of KCNN2 mutation. Case report: A 10-year-old male presented with a clinical syndrome of tremor and myoclonus. Electrophysiology demonstrated muscle activity indicative of myoclonus dystonia, an observation that was not appreciated clinically. Genetic testing revealed an abnormality in the KCNN 2 gene, not present in the parents, known to cause dystonia, as the etiology. Discussion: The value of utilizing noninvasive, electrophysiological recording in pediatric movement disorders expands the precision of diagnosis, potentially informing treatment when correlated with clinical and genetic findings.Publication Physiology of Tremor Reduction by Putting the Hands Together in Essential Tremor(2022) McGurrin, Patrick; Vial Undurraga, Felipe; Osterholt, Thomas; Norato, Gina; Khan, Imran; Haubenberger, Dietrich; Ehrlich, Debra; Hallett, MarkBackground: Background Essential tremor is a common movement disorder, characterized by 4ā12 Hz tremor of the hands and arms that can affect many activities of daily living. It has been reported by patients that when performing tasks bimanually their tremor is reduced, but why this happens is unknown. Objectives: Objectives We measured patientsā tremors in different conditions when performed with 1 hand and 2 hands to observe if bimanual task performance changes the characteristics of the tremor. Methods: Methods A total of 10 patients with essential tremor participated in the study. Electromyographic electrodes were attached bilaterally to the wrist flexor and extensor muscles, and accelerometers were attached to the dorsum of the hands. For each condition, holding a cup, wingbeat, and extending both arms up, data were collected with a single hand and bimanually with the hands touching. Results: Results When the hands were touching, there was a significant decrease in both accelerometric and electromyographic power at the tremor frequency. In addition, there was a decrease in coherence between accelerometer and electromyography on the same side. There was no change in the tremor frequency. Conclusions: Conclusions Tremor amplitude does decrease when the hands are together. Together, the characteristics underlying the decrease in tremor amplitude may indicate a decrease in power of the central oscillator driving the tremor, which we speculate is attributed to the differences in unimanual and bimanual motor control. However, given the small sample size, we note that future hypothesis-driven studies with an a priori power analysis will be required to further explore this phenomenon.Publication Identifying transcranial magnetic stimulation induced EEG signatures of different neuronal elements in primary motor cortex(2022) Ni, Zhen; Pajevic, Sinisa; Chen, Li; Leodori, Giorgio; Vial Undurraga, Felipe; Avram, Alexandru V.; Zhang, Yong; Mc Gurrin, Patrick; Cohen, Leonardo G.; Basser, Peter J.; Hallett, MarkObjective: To investigate the neuronal elements involved in the activation of corticospinal neurons in the primary motor cortex (M1). Methods: We studied 10 healthy subjects. Cortical evoked potentials with different components induced by monophasic transcranial magnetic stimulation (TMS) in anterior-posterior and posterior-anterior currents recorded with electroencephalography (EEG) were analyzed. Results: EEG signatures with P25 and N45 components recorded at the C3 electrode with posterior-anterior current were larger than those with anterior-posterior current, while the signatures with P180 and N280 components recorded at the FC1 electrode with anterior-posterior current were larger than those with posterior-anterior current. The source localization analysis revealed that the cortical evoked potential with anterior-posterior current distributed both in the M1 and premotor cortex while that with posterior-anterior current only located in the M1. Conclusions: We conclude that the activation of corticospinal pyramidal neurons in the M1 is affected by various neuronal elements including the local intracortical circuits in the M1 and inputs from premotor cortex with different sensitivities to TMS in opposite current directions. Significance: Our finding helped answer a longstanding question about how the corticospinal pathway from the M1 is functionally organized and activated.Publication Global Perceptions and Utilization of Clinical Neurophysiology in Movement Disorders(2024) Kassavetis, Panagiotis; Chen, Robert; Ganos, Christos; Hallett, Mark; Hamada, Masashi; Latorre, Anna; Pal, Pramod; Schwingenschuh, Petra; Vial Undurraga, Felipe; Tijssen, Marina; Merchant, ShabbirBackground: Clinical neurophysiology (CNP) involves the use of neurophysiological techniques to make an accurate clinical diagnosis, to quantify the severity, and to measure the treatment response. Despite several studies showing CNP to be a useful diagnostic tool in Movement Disorders (MD), its more widespread utilization in clinical practice has been limited. Objectives: To better understand the current availability, global perceptions, and challenges for implementation of diagnostic CNP in the clinical practice of MD. Methods: The International Parkinson and Movement Disorders Society (IPMDS) formed a Task Force on CNP. The Task Force distributed an online survey via email to all the members of the IPMDS between August 5 and 30, 2021. Descriptive statistics were used for analysis of the survey results. Some results are presented by IPMDS geographical sections namely PanAmerican (PAS), European (ES), African (AFR), Asian and Oceanian (AOS). Results: Four hundred and ninety-one IPMDS members (52% males), from 196 countries, responded. The majority of responders from the AFR (65%) and PAS (63%) sections had no formal training in diagnostic CNP (40% for AOS and 37% for ES). The most commonly used techniques are electroencephalography (EEG) (72%) followed by surface EMG (71%). The majority of responders think that CNP is somewhat valuable or very valuable in the assessment of MD. All the sections identified "lack of training" as one of the biggest challenges for diagnostic CNP studies in MD. Conclusions: CNP is perceived to be a useful diagnostic tool in MD. Several challenges were identified that prevent widespread utilization of CNP in MD.