Document Detail

Refined exercise testing can aid DNA-based diagnosis in muscle channelopathies.
MedLine Citation:
PMID:  21387378     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: To improve the accuracy of genotype prediction and guide genetic testing in patients with muscle channelopathies we applied and refined specialized electrophysiological exercise test parameters.
METHODS: We studied 56 genetically confirmed patients and 65 controls using needle electromyography, the long exercise test, and short exercise tests at room temperature, after cooling, and rewarming.
RESULTS: Concordant amplitude-and-area decrements were more reliable than amplitude-only measurements when interpreting patterns of change during the short exercise tests. Concordant amplitude-and-area pattern I and pattern II decrements of >20% were 100% specific for paramyotonia congenita and myotonia congenita, respectively. When decrements at room temperature and after cooling were <20%, a repeat short exercise test after rewarming was useful in patients with myotonia congenita. Area measurements and rewarming distinguished true temperature sensitivity from amplitude reduction due to cold-induced slowing of muscle fiber conduction. In patients with negative short exercise tests, symptomatic eye closure myotonia predicted sodium channel myotonia over myotonia congenita. Distinctive "tornado-shaped" neuromyotonia-like discharges may be seen in patients with paramyotonia congenita. In the long exercise test, area decrements from pre-exercise baseline were more sensitive than amplitude decrements-from-maximum-compound muscle action potential (CMAP) in patients with Andersen-Tawil syndrome. Possible ethnic differences in the normative data of the long exercise test argue for the use of appropriate ethnically-matched controls.
INTERPRETATION: Concordant CMAP amplitude-and-area decrements of >20% allow more reliable interpretation of the short exercise tests and aid accurate DNA-based diagnosis. In patients with negative exercise tests, specific clinical features are helpful in differentiating sodium from chloride channel myotonia. A modified algorithm is suggested.
S Veronica Tan; Emma Matthews; Melissa Barber; James A Burge; Sanjeev Rajakulendran; Doreen Fialho; Richa Sud; Andrea Haworth; Martin Koltzenburg; Michael G Hanna
Related Documents :
6801738 - Seasonal variation in thyrotropin-releasing hormone (trh) content of different brain re...
12614748 - Conjunctival hyperemia in healthy subjects after short-term dosing with latanoprost, bi...
23846128 - Detection of changes in muscle oxygen saturation in the human leg: a comparison of two ...
24033388 - Quadriceps strength and endurance in fibrotic idiopathic interstitial pneumonia.
7594208 - Reaction of pituitary-adrenal and autonomic nervous systems to stress in trained and un...
23592678 - Aerobic exercise alone results in clinically significant weight loss for men and women:...
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Annals of neurology     Volume:  69     ISSN:  1531-8249     ISO Abbreviation:  Ann. Neurol.     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-03-09     Completed Date:  2011-05-11     Revised Date:  2013-06-30    
Medline Journal Info:
Nlm Unique ID:  7707449     Medline TA:  Ann Neurol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  328-40     Citation Subset:  IM    
Copyright Information:
Copyright © 2011 American Neurological Association.
Medical Research Council Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, University College London, Institute of Neurology London, UK.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Channelopathies / diagnosis*,  genetics
Exercise Test*
Middle Aged
Muscle Weakness / diagnosis*,  genetics
Muscle, Skeletal / pathology*
Myotonic Disorders / diagnosis*,  genetics
Grant Support
5 U54 NS059065-05S2/NS/NINDS NIH HHS; 5U54RR019498-05/RR/NCRR NIH HHS; G0601943//Medical Research Council; R13 NS057995/NS/NINDS NIH HHS; U54 NS059065-065363/NS/NINDS NIH HHS

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  Cerebral amyloid angiopathy pathology and cognitive domains in older persons.
Next Document:  Ciprofloxacin prevents myelination delay in neonatal rats subjected to E. coli sepsis.