Congenital muscular dystrophy: light and electron microscopic observations.

Hypotonia beginning at birth or early in the neo-natal period can be caused by one of the following: (1) infantile muscular atrophy; (2) benign congenital hypotonia; (3) symptomatic hypotonia (Walton, 1960). Infantile muscular atrophy is an established clinicopathological disorder in which muscular atrophy is secondary to disease of the motor neurone. Benign congenital hypotonia is characterized by onset of hypotonia at birth or in the early neonatal period, improvement of hypotonia with age, and eventual complete recovery. No pathological alterations are noted in the muscles of these children. Symptomatic hypotonia refers to a variety of conditions characterized by hypotonia at birth and includes such varied diseases as myositis, myasthenia gravis, muscular glycogenosis, hypotonia of cretinism, and mental retardation. A much less frequent cause of symptomatic hypotonia is congenital muscular dystrophy. Greenfield, Cornman, and Shy (1958) considered congenital muscular dystrophy among disorders of muscle that can produce weakness and hypotonia at birth or in the early weeks of life. Banker, Victor, and Adams (1957) correlated clinicopathological findings in two male sibs suffering from congenital muscular dystrophy. One of their patients presented the clinical picture of arthrogryposis multiplex con-genita, whereas the other had flaccid weakness without contractures at birth. Histological evidence of muscular dystrophy in children with congenital hypotonia has been recorded by various authors The purpose of this report is to describe the pathology of muscle in six cases of congenital muscular dystrophy with particular emphasis on ultrastructure. MATERIAL AND METHODS All six patients presented with hypotonia at birth. Four of the patients were females and two were males. In three (cases 1, 2, 3) the hypotonia and weakness were severe and generalized. Neck muscles were most severely affected. Contractures developed in the post-natal period. Weakness either remained stationary, showed slight improvement, or slight and slow progression with age. In the other three cases (cases 4, 5, 6) hypotonia and weakness were of slight to moderate degrees of severity. The condition remained stationary or improved with age. Electromyography revealed a myopathic pattern in all six cases. Creatine phosphokinase values were normal or slightly elevated in the clinically severe cases and moderately elevated in the clinically milder cases. Details of clinical findings in each of the six cases are given in Table I. Criteria for clinical differentiation of congenital muscular dystrophy from other better known and more common types of dystrophy are presented elsewhere (Zellweger, Afifi, McCormick, and Mergner, 1967 a, b). …