Diffusely Increased Insertional Activity: “EMG Disease” or Asymptomatic Myotonia Congenita? A Report of 2 Cases

• Published in: Archives of physical medicine and rehabilitation Vol. 88; no. 9; pp. 1212 - 1213
• Main Authors: Mitchell, Christopher W., MD, Bertorini, Tulio E., MD
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-09-2007; Elsevier
• Subjects: Adult; Biological and medical sciences; Case report; Chloride channels; Chloride Channels - genetics; Chloride Channels - metabolism; Codon, Nonsense; Diseases of striated muscles. Neuromuscular diseases; DNA - genetics; Electrodiagnosis. Electric activity recording; Electromyography; Female; Follow-Up Studies; Humans; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Middle Aged; Miscellaneous; Muscle, Skeletal - metabolism; Muscle, Skeletal - physiopathology; Myotonia congenita; Myotonia Congenita - genetics; Myotonia Congenita - physiopathology; Myotonia Congenita - rehabilitation; Nervous system; Neurology; Physical Medicine and Rehabilitation; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); Rehabilitation; Severity of Illness Index; Chloride channels; Case report; Electromyography; Rehabilitation; Myotonia congenita; Human; Neuromuscular diseases; Nervous system diseases; Myotonia; Asymptomatic; Case study; Electrodiagnosis; Symptomatology; Phenotype; Reeducation; Needle; Mutation
• ISSN: 0003-9993; 1532-821X
• DOI: 10.1016/j.apmr.2007.06.013

Abstract Mitchell CW, Bertorini TE. Diffusely increased insertional activity: “EMG disease” or asymptomatic myotonia congenita? A report of 2 cases. The term “EMG disease” is used by some to describe the unexpected finding of diffusely increased insertional activity on needle electromyography in an otherwise asymptomatic person. The cause is unknown, but it has been hypothesized that these patients actually have a subclinical myotonic disorder. We describe 2 patients with diffusely increased insertional activity on electromyography who had mutations of the CLCN1 gene associated with myotonia congenita. Neither patient had symptoms or reproducible signs of this disorder. We propose that asymptomatic patients with CLCN1 mutations may at least partially account for the EMG disease phenotype.