Masquerading Myotonia—Myotonia Dystrophica Mimicking Proximal Myopathy: A Case Report

Myotonia dystrophica is a genetically mediated neuromuscular disorder that results in myotonia and advancing muscle weakness, together with various system impairments.Patients who exhibit pure myotonic symptoms without any visible systemic symptoms are difficult to diagnose.This case report is about a 35-year-old male who experienced fatigue and proximal muscle weakness for more than 15 years.The team conducted a complete clinical assessment and performed extensive laboratory tests to identify different causes of proximal myopathy and conducted neurophysiological assessments.The electromyography (EMG) showed typical runs of myotonic discharges.The medical team reached a diagnosis of pure myotonia dystrophica through evaluation of clinical data, laboratory results, and electrophysiological evidence.This case demonstrates how proper sequential assessment leads to better diagnostic results for uncommon myotonic disorders through the use of EMG.