Objective: Report the case of a patient with a novel SGCE gene mutation and isolated myoclonus phenotype who was successfully treated with deep brain stimulation (DBS).

Background: Myoclonus-dystonia is an inherited disorder characterized by a combination of myoclonic jerks and dystonia. Mutations in the SGCE gene represent the main known genetic cause. In the last years, DBS has shown significant promise in treating these patients. There is only one report in the literature of a patient with positive SGCE mutation and isolated myoclonus phenotype who has been successfully treated with DBS.

Method: We present a case of a 16-year-old young man with a history of quick jerks since childhood. They progressed gradually over the years involving the entire body and interfering with most of his daily activities. He had no dystonia. Genetic testing identified a single base deletion in exon 3 of the SGCE gene, considered very likely pathogenic. After unsuccessfully trying several oral medications, he underwent DBS of the globus pallidus internus (GPi).

Results: His Unified Myoclonus Rating Scale score during rest and with action improved by 92.8% and 82.6% respectively.

Conclusion: We present a case of myoclonus-dystonia due to a novel SGCE mutation. The striking effect of DBS on myoclonic jerks confirms the superior benefit of DBS over oral medications for patients with genetically confirmed myoclonus-dystonia. Further study is needed to determine the role of mutation status in predicting DBS response, especially considering that myoclonus-dystonia is genetically heterogeneous.

References: [1] Nardocci N. Myoclonus-Dystonia Syndrome. In: Weiner WJ, Tolosa E. Handbook of Clinical Neurology, Vol. 100: Hyperkinetic Movement Disorders. 1st edition. Elsevier;2011:563-575 [2] Roze E, Lang AE, Vidailhet M. Myoclonus-dystonia: classification, phenomenology, pathogenesis, and treatment. Curr Opin Neurol. 2018; 31:484-490 [3] Peall KJ, Dijk JM, Saunders-Pullman R, et al. Psychiatric disorders, myoclonus dystonia and SGCE: an international study. Ann Clin Transl Neurol. 2016; 3(1):4-11 [4] Rachad L, El Kadmiri N, Slassi I, El Otmani H, Nadifi S. Genetic Aspects of Myoclonus–Dystonia Syndrome (MDS). Mol Neurobiol. 2017; 54:939-942 [5] HGMD® gene result. [online] Available at: http://www.hgmd.cf.ac.uk/ac/gene.php?gene=SGCE [Accessed 21 Nov. 2019]. [6] Rughani AI, Lozano AM. Surgical Treatment of Myoclonus Dystonia Syndrome. Mov Disord. 2013; 28(3):282-287 [7] Kosutzka Z, Tisch S, Bonnet C, et al. Long-Term GPi-DBS Improves Motor Features in Myoclonus-Dystonia and Enhances Social Adjustment. Mov Disord. 2019; 34(1):87-94 [8] Nardocci N, Zorzi G, Barzaghi C, et al. Myoclonus- dystonia syndrome: clinical presentation, disease course, and genetic features in 11 families. Mov Disord. 2008; 23:28–34 [9] Ramdhani RA, Frucht SJ, Behnegar A, Kopell BH. Improvement of Isolated Myoclonus Phenotype in Myoclonus Dystonia after Pallidal Deep Brain Stimulation. Tremor Other Hyperkinet Mov. 2016; 6:369. doi: 10.7916/D8F47P0C [10] Zhang YQ, Wang JW, Wang YP, Zhang XH, Li JP. Thalamus Stimulation for Myoclonus Dystonia Syndrome: Five Cases and Long-Term Follow-up. World Neurosurg. 2019 Feb;122:e933-e939 [11] Luciano MS, Ozelius L, Sims K, et al. Responsiveness to levodopa in epsilon-sarcoglycan deletions. Mov Disord. 2009; 24:425-428 [12] Levy A, Chen R. Myoclonus: Pathophysiology and Treatment Options. Curr Treat Options Neurol. 2016; 18(5):21. doi: 10.1007/s11940-016-0404-7 [13] Lee JH, Lyoo CH, Lee MS. A patient with genetically confirmed myoclonus-dystonia responded to anticholinergic treatment and improved spontaneously, J Clin Neurol. 2011; 7(4):231–232 [14] Luciano AY, Jinnah H, Pfeiffer RF, et al. Treatment of myoclonus-dystonia syndrome with tetrabenazine. Parkinsonism Relat Disord. 2014; 20:1423–1426 [15] Haque E, Vidailhet M, Cozic N, et al. A randomized, controlled, double-blind, crossover trial of zonisamide in myoclonus-dystonia. Neurology. 2016; 86:1729–1735 [16] Gruber D, Kuhn AA, Schoenecker T, et al. Pallidal and thalamic deep brain stimulation in myoclonus-dystonia. Mov Disord. 2010; 25:1733–1743 [17] Jinnah HA, Alterman R, Klein C, et al. Deep Brain Stimulation for Dystonia: A Novel Perspective on the Value of Genetic Testing. J Neural Transm. 2017; 124(4):417–430

« Back to MDS Virtual Congress 2020

MDS Abstracts - https://www.mdsabstracts.org/abstract/a-case-report-of-myoclonus-dystonia-with-isolated-myoclonus-phenotype-and-novel-mutation-successfully-treated-with-deep-brain-stimulation/