title: Muscle ultrasound measurements and functional muscle parameters in non-dystrophic myotonias suggest structural muscle changes.
abstract: Patients with non-dystrophic myotonias, including chloride (myotonia congenita) and sodium channelopathies (paramyotonia congenita/potassium aggravated myotonias), may show muscular hypertrophy in combination with some histopathological abnormalities. However, the extent of muscle changes has never been assessed objectively in a large group genetically confirmed patients. This study quantitatively determines echo intensities, thicknesses, ranges-of-motion and force of four skeletal muscles in 63 genetically confirmed patients. The main findings revealed elevated echo intensities in all muscles except the rectus femoris (+1.3-2.2SD, p<0.0001), and hypertrophy in the arms (+0.5-0.9SD, p<0.01). Muscle echo intensities were inversely correlated to the corresponding ranges-of-motion (biceps brachii: r= -0.43; p<0.001, forearm flexors: r= -0.47; p<0.001, rectus femoris: r= -0.40; p=0.001, and tibial anterior: r= -0.27; p=0.04) and correlated positively to age (r=0.22; p=0.05). The echo intensity of the forearm flexors was inversely correlated to their muscles' force (r= -0.30; p=0.02). Together, these data suggest that non-dystrophic myotonias may lead to structural muscle changes.
authors.affiliation: Department of Neurology, Maastricht University Medical Centre, Maastricht, The Netherlands. jeroen.trip@online.nl
authors.forename: J
authors.initials: J
authors.lastname: Trip
authors.forename: S
authors.initials: S
authors.lastname: Pillen
authors.forename: C G
authors.initials: CG
authors.lastname: Faber
authors.forename: B G M
authors.initials: BG
authors.lastname: van Engelen
authors.forename: M J
authors.initials: MJ
authors.lastname: Zwarts
authors.forename: G
authors.initials: G
authors.lastname: Drost
mesh_terms: D000328:Adult; D000368:Aged; D001132:Arm / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D053447:Channelopathies / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D007866:Leg / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000000981:diagnostic imaging* / Q000473:pathology*; D053580:Muscle Strength / Q000502:physiology; D018908:Muscle Weakness / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology; D020967:Myotonic Disorders / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology; D011237:Predictive Value of Tests; D011379:Prognosis; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014463:Ultrasonography / Q000379:methods; D055815:Young Adult