Theodore L. Munsat

The Schwartz-Jampel syndrome

Abstract Patients with the Schwartz-Jampel syndrome represent an example of continuous muscle fiber activity at rest. Abolition of the continuous repetitive discharges with curare showed that this was not myotonia as previously reported. The likelihood that the abnormal discharges originated from the muscle component of the neuromuscular junction rather than the nerve was suggested by the observation that spontaneous electrical activity persisted long after peripheral nerve injury in 1 of the cases. Electron-microscopic examination of biopsy specimens showed marked dilatation of the endoplasmic reticulum of skin fibroblasts and moderate dilatation of the sarcoplasmic reticulum of muscle fibres. Tissue culture studies of the fibroblasts revealed a low level of lipid label incorporation representing a non-specific depression of the synthetic machinery of these cells. These studies failed to demonstrate any mucopolysaccharide abnormality, even though the radiologic findings in 1 of the cases were consistent with those found in the Morquio-Brailsford syndrome. Histochemical evaluation showed hypertrophy of both Type I and II fibers with SDH activity uniformly high in both fiber types. AChE staining revealed marked diffuse activity throughout the sarcoplasm of the muscle similar to that reported in embryonic muscle. These findings suggest the possibility that the abnormality in this syndrome occurs during fetal development.

The Lysosome: A Role in Disease

Abstract Increasing interest in elucidating the role of the lysosome in intracellular metabolic economy has resulted in a deeper understanding of some inborn errors of metabolism, as well as a clea...

The Differential Diagnosis of Neuromuscular Weakness in Infancy and Childhood

The striking elevation of serum enzymes, especially creatine phosphokinase, in preclinical and early Duchenne muscular dystrophy greatly assists the clinical diagnosis. Minor, but often very helpful, elevations may also be found in the female carrier of Duchenne dystrophy and in patients with other more slowly evolving forms of dystrophy. Histochemical and electron microscopic findings in dystrophy are non‐specific, as are many light microscopic changes. Clinical subgroups of the dystrophic myopathies are based on age of onset, mode of inheritance, distribution of muscular weakness and evolution.

The differential diagnosis of neuromuscular weakness in infancy and childhood. I. Non-dystrophic disorders.

Of the non‐dystrophic causes of neuromuscular weakness in infancy and childhood, differentiating the diseases of the anterior horn cell from those of the muscle fiber poses the greatest clinical problem and often requires histologic and electrophysiologic studies. It has become apparent that certain forms of anterior horn cell disease (infantile spinal‐muscular atrophy) may present a spectrum of involvement from an acute, fulminating course to a much more benign and arrested syndrome. Study of the congénital, nonprogressive (or slowly progressive) myopathy syndrome has revealed a variety of interesting structural and histochemical altérations in some patients. This includes altérations in Z‐band structure, absence of oxidative enzymes in the central part of the muscle fiber and mitochondrial abnormalities. With the advent of electron microscopy and better histochemical techniques, new entities are being reported with great frequency, and constant révision of classification and pathogenetic theory is necessary.