To the Editor—
Reports on the skeletal muscle pathology in infantile myotonic dystrophy (IMD) may be few, as Drs Sarnat and Silbert remark (Arch Neurol 33:466, 1976). Nevertheless, in the face of this paucity they overlooked or omitted our report1 in which biopsy specimens from four patients who had been severely affected in the neonatal period were obtained at 13, 18, and 22 months, and 6 years of age. It is instructive to compare the reports. The muscle fibers studies by Sarnat and Silbert were all obtained before the third week of life. They showed a striking prevalence of central nuclei and deficient differentiation into histochemical fiber types. These findings are indeed interpretable as maturational retardation, though not necessarily "arrest." In our patients clinical improvement had occurred, as so often happens in IMD, after the first few months. Central nuclei were somewhat more numerous than normal, and even the
Karpati G, Carpenter S. Maturational Arrest. Arch Neurol. 1976;33(12):847. doi:10.1001/archneur.1976.00500120051010
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