Yi H, Liu CX, Ye SX, Liu YL. Special electromyographic features in a child with paramyotonia congenita: A case report and review of literature. World J Clin Cases 2024; 12(3): 587-595 [PMID: 38322461 DOI: 10.12998/wjcc.v12.i3.587]
Corresponding Author of This Article
Yu-Lin Liu, MA, Deputy Director, Department of Neuroelectrophysiology, Qilu Children’s Hospital of Shandong University, No. 23976 Jingshi Road, Jinan 250000, Shandong Province, China. liuyulin1122@126.com
Research Domain of This Article
Clinical Neurology
Article-Type of This Article
Case Report
Open-Access Policy of This Article
This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
World J Clin Cases. Jan 26, 2024; 12(3): 587-595 Published online Jan 26, 2024. doi: 10.12998/wjcc.v12.i3.587
Special electromyographic features in a child with paramyotonia congenita: A case report and review of literature
Hui Yi, Chen-Xiang Liu, Shu-Xin Ye, Yu-Lin Liu
Hui Yi, Shu-Xin Ye, Yu-Lin Liu, Department of Neuroelectrophysiology, Qilu Children’s Hospital of Shandong University, Jinan 250000, Shandong Province, China
Chen-Xiang Liu, Department of Neuroelectrophysiology, University of Health and Rehabilitation Sciences (Qingdao Municipal Hospital), Qingdao 266000, Shandong Province, China
Author contributions: Yi H wrote the article and reviewed the relevant literature; Liu CX was involved in the translation of the paper; Ye SX presented a new theoretical perspective on this case of electromyography; and all authors reviewed and edited the article and approved the final version of the article.
Informed consent statement: Written informed consent of this paper was obtained from the patient’s legal guardian.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
CARE Checklist (2016) statement: The authors have read the CARE Checklist (2016), and the manuscript was prepared and revised according to the CARE Checklist (2016).
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Yu-Lin Liu, MA, Deputy Director, Department of Neuroelectrophysiology, Qilu Children’s Hospital of Shandong University, No. 23976 Jingshi Road, Jinan 250000, Shandong Province, China. liuyulin1122@126.com
Received: September 21, 2023 Peer-review started: September 21, 2023 First decision: November 20, 2023 Revised: December 4, 2023 Accepted: January 4, 2024 Article in press: January 4, 2024 Published online: January 26, 2024 Processing time: 119 Days and 4.3 Hours
Abstract
BACKGROUND
Paramyotonia congenita (PMC) stands as a rare sodium channelopaty of skeletal muscle, initially identified by Eulenburg. The identification of PMC often relies on electromyography (EMG), a diagnostic technique. The child’s needle EMG unveiled trains of myotonic discharges with notably giant amplitudes, alongside irregular wave trains of myotonic discharges. This distinctive observation had not surfaced in earlier studies.
CASE SUMMARY
We report the case of a 3-year-old female child with PMC, who exhibited laryngeal stridor, muffled speech, myotonia from birth. Cold, exposure to cool water, crying, and physical activity exacerbated the myotonia, which was relieved in warmth, yet never normalized. Percussion myotonia was observable in bilateral biceps. Myotonia symptoms remained unchanged after potassium-rich food consumption like bananas. Hyperkalemic periodic paralysis was excluded. Cranial magnetic resonance imaging yielded normal results. Blood potassium remained within normal range, while creatine kinase showed slight elevation. Exome-wide genetic testing pinpointed a heterozygous mutation on chromosome SCN4A: c.3917G>A (p.G1306E). After a six-month mexiletine regimen, symptoms alleviated.
CONCLUSION
In this case revealed the two types of myotonic discharges, and had not been documented in other studies. We underscore two distinctive features: Giant-amplitude potentials and irregular waves.
Core Tip: Paramyotonia congenita (PMC) is a rare sodium channelopathy of skeletal muscle, first identified by Eulenburg. The distinguishing feature of PMC is paradoxical myotonia, where myotonia worsens with cold and exercise. In instances where genetic testing is unavailable, electromyography (EMG) is a swift, cost-effective diagnostic and differential diagnostic method for PMC. This article elaborates on the EMG characteristics of a recently diagnosed PMC case at our hospital. In this particular case revealed the two types of myotonic discharges, and had not been documented in other studies. We underscore two distinctive features: Giant-amplitude potentials and irregular waves.
