PMC10041432_01
Top left: Original image of muscle biopsy of the diaphragm showing a dystrophic aspect with many hypertrophic muscle fibers in a matrix of connective tissue, as published in the report by Leijten et al. Top right: Muscle biopsy from the quadriceps muscle (A) and diaphragm muscle (B). Quadriceps muscle is normal. However, the diaphragm shows a dystrophic picture with hypertrophic fibers and increase of endomysial connective tissue. Bar: 50 micron. Hematoxilin-Phloxine (HP) stain. Bottom: Ultrastructure of a normal neuromuscular junction (NMJ) from a 11-month-old girl (Figure A). Figures B, C, and D show abnormal NJMs in the diaphragm of the patient in this report. Arrows point to the primary cleft between the neuronal (n) and muscular (m) part of the NMJs (Figure A, B, C, and D). The neuronal part (n) of the NMJs contains mitochondria and small vesicles with acetylcholine. Note the presence of many secondary clefts invaginating the muscular part (Figure A) and the almost complete absence of these invaginations in the abnormal NMJs.
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No muscle atrophy was observed (Fig. 1). EMG with RNS at the age of 33 showed a decrement of the compound muscle action potential amplitude of the trapezius muscle (Fig. 1). The ultrasound of the diaphragm showed severe muscle atrophy of the right hemidiaphragm (Fig. 1) and no thickening during inspiration.
Top left: Clinical photographs, taken at the age of 32, showing a mild ophthalmoplegia of the right eye with upward-outward gaze and a lack of muscular atrophy. Top right: EMG with RNS showing decrement of CMAP amplitude of the trapezius muscle. Bottom: Ultrasound of right and left side of the diaphragm. The right side of the diaphragm shows severe muscle atrophy and no thickening during inspiration. The left side shows no abnormalities. The thickness at end-expiration is 1.7 mm and thickening ratio during inspiration is 3.1.
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No fat cells or fiber splitting was observed (Fig. 2). The second quadriceps biopsy showed normal fiber diameters (Fig. 2), a slightly increased percentage of type I fibers, but no predominance. Furthermore, diffuse infiltration of neutrophils and a clearly dystrophic aspect caused by endomysial fibrosis, many rounded hypertrophic fibers (Fig. 2), and sporadically an atrophic fiber were observed. Furthermore, 5 abnormal neuromuscular junctions (NMJs) from 3 motor endplates were seen with severe loss of secondary synaptic clefts (Fig. 2).