Browsing by Author "Haubenberger, Dietrich"
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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.; Bönnemann, 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 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 4–12 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 patients’ 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.Item Tremoroton, a new free online platform for tremor analysis(2020) Vial Undurraga, Felipe; McGurrin, Patrick; Osterholt, Thomas; Ehrlich, Debra; Haubenberger, Dietrich; Hallett, MarkObjective: The electrophysiological classification of tremors can be a key element in the diagnosis and can facilitate treatment of a patient with tremor; however, the ability to conduct electrophysiological studies of tremor is not widely available. The purpose of this study was to develop and validate a free online platform for tremor analysis. Methods: An online platform for tremor analysis was developed using "R" language; called Tremoroton". For validation, we compared the frequency estimation of the tremor obtained with Tremoroton compared with a commercially available software in a cohort of 20 patients (10 with essential tremor and 10 with Parkinson diagnosis), comparing the activity recorded on the accelerometer, extensor carpi radialis and flexor carpi radialis EMG. An intraclass correlation coefficient was used for the comparison. Results: The final version of tremoroton is now online. It allows reading up to 6 channels, and will do time, frequency, time-frequency analysis and calculate coherence. We demonstrated a high correlation in frequency measurements (0.97 (0.945-0.984, 95% IC) for the accelerometers, 0.98 (0.977-0.994, 95% IC) for the extensor carpi radialis EMG, and 0.99 (0.987-0.997, 95% IC) for the flexor carpi radialis EMG) when compared to a commercial software. Conclusion: We were able to develop and validate a free online platform for tremor analysis. Significance: Making this tool available should help expanding tremor analysis techniques from research to the clinical setting.