Characteristic MRI Findings of upper Limb Muscle Involvement in Myotonic Dystrophy Type 1

Abstract

The objective of our study was to evaluate the relation between muscle MRI findings and upper limb weakness with grip myotonia in patients with myotonic dystrophy type 1 (DM1). Seventeen patients with DM1 were evaluated by manual muscle strength testing and muscle MRI of the upper limbs. Many DM1 patients presenting with decreased grasping power frequently showed high intensity signals in the flexor digitorum profundus (FDP) muscles on T1-weighted imaging. Patients presenting with upper limb weakness frequently also showed high intensity signals in the flexor pollicis longus, abductor pollicis longus, and extensor pollicis muscles. Disturbances of the distal muscles of the upper limbs were predominant in all DM1 patients. Some DM1 patients with a prolonged disease duration showed involvement of not only distal muscles but also proximal muscles in the upper limbs. Muscle involvement of the upper limbs on MRI strongly correlated positively with the disease duration or the numbers of CTG repeats. To our knowledge, this is the first study to provide a detailed description of the distribution and severity of affected muscles of the upper limbs on MRI in patients with DM1. We conclude that muscle MRI findings are very useful for identifying affected muscles and predicting the risk of muscle weakness in the upper limbs of DM1 patients.

Muscle magnetic resonance imaging in myotonic dystrophy type 1 (DM1): Refining muscle involvement and implications for clinical trials

“…Several MRI studies, mainly including small cohorts of patients and focusing on the lower limbs, have assessed the pattern and severity of muscle involvement in DM1 [ 15 , 16 , 17 , 18 , 19 ]. Two other studies explored the muscle involvement of upper limbs but omitted head, neck and scapular girdle muscles [ 20 , 21 ]. A recent study analyzed the fat fraction and atrophy in 20 lower extremity muscles of 33 DM1 patients by quantitative muscle MRI, suggesting it as a valuable biomarker for this disease [ 22 ].…”

Whole-Body Muscle MRI Characteristics of LAMA2 Gene Mutation Congenital Muscular Dystrophy Children

“…This sign has been suggested to be correlated to disease severity and level of disability [30]. Additionally, in myotonic muscular dystrophy, among upper limb muscles, the flexor digitorum profundus muscle was most affected, followed by the adductor pollicis longus and the extensor pollicis longus muscles [32, 33].…”

Clinical characteristics of different forms of myotonic dystrophy type 1

“…При проведении ряда исследований мышц методом магнитно-резонансной томографии было обнаружено, что жировая дегенерация изначально выявляется в следующих мышцах: медиальной икроножной, камбаловидной, передней большеберцовой и глубоком сгибателе пальцев рук. Измене-ния на томограмме коррелируют с возрастом пациента, количеством CTG-повторов и степенью выраженности пареза [24,65]. В настоящее время в клинической практике для диагностики МД1 проведение морфологического исследования биоптата мышцы нецелесообразно ввиду неспецифичности изменений [29].…”