Author(s): Jackson CE, Barohn RJ, Ptacek LJ
The diagnosis of paramyotonia congenita (PC) can be aided by demonstrating a decrease in compound motor action potential amplitude after exercise and a decrement on repetitive stimulation, following cold exposure. We report a patient with PC who presented with complaints of cold-induced hand and jaw stiffening, in the absence of any episodes of weakness. Treatment with mexiletine led to resolution of the abnormalities exhibited during a short exercise test and repetitive stimulation following ice bath immersion. Molecular genetic analysis revealed a missense mutation (cytosine to thymidine) on chromosome 17 in the alpha-subunit of the skeletal muscle sodium channel gene that results in the replacement of threonine with methionine. This case demonstrates that, despite the absence of weakness, the short exercise test following cold exposure can be used to confirm the diagnosis of PC in patients without episodic weakness. Furthermore, improvement of the electrophysiologic abnormalities with mexiletine was documented, corresponding with clinical improvement.
Referred From: https://www.ncbi.nlm.nih.gov/pubmed/8008003
Author(s): George AL Jr
Author(s): Jurkat-Rott K, Holzherr B, Fauler M, Lehmann-Horn F
Author(s): Hudson AJ, Ebers GC, Bulman DE
Author(s): George AL Jr, Komisarof J, Kallen RG, Barchi RL
Author(s): West JW, Patton DE, Scheuer T, Wang Y, Goldin AL, et al.
Author(s): Popa MO, Alekov AK, Bail S, Lehmann-Horn F, Lerche H
Author(s): Chahine M, George AL Jr, Zhou M, Ji S, Sun W, et al.
Author(s): Yang N, Ji S, Zhou M, Ptácek LJ, Barchi RL, et al.
Author(s): Bouhours M, Luce S, Sternberg D, Willer JC, Fontaine B, et al.
Author(s): Kinoshita M, Sasaki R, Nagano T, Matsuda A, Nakamura S, et al.
Author(s): Lehmann-Horn F, Jurkat-Rott K
Author(s): Wang GK, Russell C, Wang SY