Person: Vial Undurraga, Felipe
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Vial Undurraga
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Felipe
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Publication Electrophysiological Characterization of a MYH7 Variant with Tremor Phenotype(2023) Vial Undurraga, Felipe; Gurrin, Patrick M.; Osterholt, Thomas; Ehrlich, Debra J.; Iannacone, Susan T.; Donkervoort, Sandra; Neuhaus, Sarah B.; Chao, Katherine C.; Bƶnnemann, Carsten G.; Haubenberger, Dietrich; Hallet, MarkBackground: The concept of a myopathy with associated tremor ("myogenic tremor") in humans has been previously described for specific MYBPC1 (Myosin-Binding Protein C) variants. Here we report for the first time an individual with tremor who was found to have a de-novo likely pathogenic variant in Myosin Heavy Chain 7 (MYH7). We provide a detailed electrophysiological characterization of the tremor syndrome in a human individual with a myopathy and this pathogenic MYH7 variant to provide further insight in the phenotypic spectrum and pathomechanism of myogenic tremors in skeletal sarcomeric myopathies. Methods: Electromyographic recordings were obtained from facial muscles, as well as bilateral upper and lower extremities. Results: 10 to 11 Hz activity was observed in the face and extremities during recordings with muscle activation. There were intermittent episodes of significant left-right coherence that would modulate across muscle groups throughout the recording, but no coherence between muscles at different levels of the neuraxis. Conclusions: A possible explanation for this phenomenon is that the tremor originates at the sarcomere level within muscles, which is then picked up by muscle spindles and leads to activating input to the neuraxis segment. At the same time, the stability of the tremor frequency does suggest the presence of central oscillators at the segmental level. Thus, further studies will be needed to determine the origin of myogenic tremor and to better understand the pathomechanism.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.