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Cognitive Neuroscience 2020: MRI of the brain, limb muscles and mitochondrial disorders in myotonic dystrophy

Olga Petrovna Sidorova

Objective: To study changes in the brain and muscles, mitochondrial disorders in patients with myotonic dystrophy.

 Material and Methods: 12 patients with myotonic dystrophy were examined. Of these, 1 was diagnosed with type 2 and the remaining 1 type   of the disease. The diagnosis is confirmed by DNA diagnostics. MRI of the brain was performed. The MRI of lower and upper limb muscles   was done on the scanner built around a 1.5 Tesla (T) magnet (Optima MR450w, GE Healthcare) using a T1- and T2-weighted images. For the   muscle damage quantification by using MRI a qualitative muscle grading scale, developed by Mercuri et al., (2002) is used. Muscle atrophy   grade evaluated during MRI can be divided according to the following criteria: Grade 1 – Early moth-eaten appearance with scattered small   areas of increased signal; Grade 2a – Late moth-eaten appearance with numerous discrete areas of increased signal with beginning confluence, comprising less than 30% of the volume of the individual muscle; Grade 2b–Late moth-eaten appearance with numerous discrete areas of increased signal with beginning confluence, comprising 30–60% of the volume of the individual muscle; Grade 3–Washed-out appearance, fuzzy appearance due to confluent areas of increased signal; Grade 4–End stage appearance, muscle replaced by increased density of connective tissue and fat, with only a rim of fascia and neurovascular tissue distinguishable. For a quantitative cytochemical study of the activity of mitochondrial enzymes in peripheral blood lymphocytes, the method proposed by A.G.E. Pearse in the modification of P.P. Narcissov. The activity of four mitochondrial enzymes being involved in carbohydrate (lactate dehydrogenase, LDH), amino acid (glutamate dehydrogenase, GLDH), and fat (α-glycerophosphate dehydrogenase, α-GPDH) metabolism, as well as the enzyme of complex II of mitochondrial respiratory chain (succinate dehydrogenase, SDH) were evaluated. We also measured blood lactate level before and after a carbohydrate loading.