The exercise test distinguishes proximal myotonic myopathy from myotonic dystrophy

Sander, Howard W.; Tavoulareas, George P.; Quinto, Christine; Menkes, Daniel L.; Chokroverty, Sudhansu

doi:10.1002/(sici)1097-4598(199702)20:2<235::aid-mus17>3.0.co;2-1

Cited by 16 publications

(12 citation statements)

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“…The results of this electrophysiological study, based on examination of 2 large groups of patients with genetically proven DM1 and DM2, demonstrate that there was a marked CMAP amplitude decline after the short exercise test in DM1, as opposed to a lack of such change in DM2. These findings coincide with previous studies . A decrease in CMAP amplitude immediately after effort was found by Sander et al .…”

Section: Discussionsupporting

confidence: 93%

“…11,12,14 A decrease in CMAP amplitude immediately after effort was found by Sander et al in DM1, whereas, in DM2 the CMAP amplitude was mildly increased. 14 11,12,19 When the SET was repeated with a larger group of patients with DM2 (8 patients), it was found that the 10-s, 30-s, 60-s, and 5-min exercise tests were normal in proximal myotonic myopathy. 15 Specifically, in DM2, the post-exercise CMAP decline was 8% maximally, in contrast to DM1, whereas the maximal CMAP amplitude declines were 48% (10-s test) and 26% (30-s exercise test).…”

Section: Discussionmentioning

confidence: 81%

“…A decrease in CMAP amplitude immediately after effort was found by Sander et al . in DM1, whereas, in DM2 the CMAP amplitude was mildly increased . The Sander et al .…”

Section: Discussionmentioning

confidence: 92%

“…In 1997, Sander et al demonstrated that the 60-s exercise test is normal in DM2 compared with controls in contrast to a post-exercise amplitude decrement observed in DM1. [11][12][13][14][15] In DM1, the maximum post-exercise compound motor action potential (CMAP) amplitude decrease was 48% in a 10-s test, whereas in DM2 the maximum CMAP decline was 8%. 14 Moreover, in a further study, it was shown that 10-and 30-s exercise tests help distinguish DM2 and DM1.…”

mentioning

confidence: 99%

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Value of short exercise and short exercise with cooling tests in the diagnosis of myotonic dystrophies (DM1 AND DM2)

et al. 2013

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 81%

“…A decrease in CMAP amplitude immediately after effort was found by Sander et al . in DM1, whereas, in DM2 the CMAP amplitude was mildly increased . The Sander et al .…”

Section: Discussionmentioning

confidence: 92%

mentioning

confidence: 99%

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Value of short exercise and short exercise with cooling tests in the diagnosis of myotonic dystrophies (DM1 AND DM2)

et al. 2013

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“…The short exercise test shows a transient drop of CMAP amplitude in DM1, 57, 58 a finding that is qualitatively similar to RGM, and consistent with chloride channelopathy (see below). The distribution of myotonic discharges is less consistent in DM2.…”

Section: Laboratory and Electrophysiologic Testingsupporting

confidence: 67%

Myotonic Dystrophy

2014

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Myotonic dystrophy (dystrophia myotonica, DM) is one of the most common lethal monogenic disorders in populations of European descent. Myotonic dystrophy type 1 (DM1) was first described over a century ago. DM1 is caused by expansion of a CTG triplet repeat in the 3' non-coding region of DMPK, the gene encoding the DM protein kinase. More recently a second form of the disease, myotonic dystrophy type 2 (DM2) was recognized, which results from repeat expansion in a different gene. The DM2 expansion involves a CCTG repeat in the first intron of Zinc Finger 9 (ZNF9). Both disorders have autosomal dominant inheritance and multisystem features, including myotonic myopathy, cataract, and cardiac conduction disease. Studies suggest that the shared clinical features of DM1 and DM2 involve a novel genetic mechanism in which repetitive RNA exerts a toxic effect. The RNA toxicity stems from the expanded repeat in the transcripts from the mutant DM alleles. This chapter will review the clinical presentation and pathophysiology of DM, and discuss current management and future potential for developing targeted therapies.

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