Severe neonatal myotonic dystrophy (quadriceps femoris muscle biopsy) (1)

In transverse section, myofibers are smaller than expected, with an average diameter of 5 to 12.5µm (normal mean 15µm). About 20% of fibers have central nuclei or clear central spaces if the section is between nuclei, but no myofiber degeneration or necrosis are seen. X250. (Reproduced with permission from: Sarnat HB, O’Connor T, Byrne PA. Clinical effects of myotonic dystrophy on pregnancy and the neonate. Arch Neurol 1976;33:459-65. Copyrighted 1976, American Medical Assoc.)