Continuous Muscle Fiber Activity Research Articles

Ultrastructure of the syndrome of continuous muscle fibre activity.

The ultrastructure of muscle and the myoneural junction of a man of 60 suffering from the syndrome of continuous muscle fibre activity was studied. This syndrome is manifested by disturbances of walking, muscle weakness, permanent muscle contractions and involuntary movements. The myoneural junction was hypertrophied and showed ramifications of the secondary clefts. The presynaptic nerve ending contained no synaptic vesicles. The relationship of these findings to the disease is discussed.

The syndrome of 'continuous muscle-fibre activity' cured: further studies.

Two cases suffering from the syndrome of `continuous muscle-fibre activity' have been followed-up for 14 years. These patients have gradually gone into remission and no longer require therapy. The results of recent histology, histochemistry, and electronmicroscopy, as well as sural nerve biopsy studies, are presented. The sarcoplasmic reticulum calcium binding activity and ATPase activity are normal.

The Schwartz-Jampel syndrome: Its clinical, physiological and histological expressions

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.

Continuous muscle fiber activity in the Schwartz-Jampel syndrome

The Schwartz-Jampel syndrome is an hereditary disease characterized by shortness of stature, muscular hypertrophy, and persistent muscular contraction at rest. The electromyographic (EMG) findings have been referred to by all authors as myotonia. In the two cases described in this article, the EMG findings were quite different from ordinary myotonia. There was continuous electrical activity at rest which did not wax and wane and accounted for the persistent muscular contraction observed clinically. This activity was not abolished by deep general anesthesia. The technique of regional neuromuscular block with curare was used to determine the origin of these discharges. In contrast to classical myotonia, the discharges were abolished by curare, and muscular relaxation was achieved. However, the likelihood that they do originate from the muscle component of the neuromuscular junction rather than the peripheral nerve was suggested by the observation that spontaneous electrical activity persisted long after inadvertent nerve injury during a surgical procedure. We suggest that the term myotonia is not appropriate for the high frequency discharges observed in this syndrome. Regional intravenous perfusion with curare is a relatively simple technique which can assist in localizing the site of origin of abnormal EMG discharges. The application of this anesthetic technique to physiological studies of the motor unit is described.

The Syndrome of Continuous Muscle Fiber Activity.

Excerpt An unusual disorder of unknown cause, characterized by continuous muscle fasciculation and myotonia in otherwise normal young men, was first described by Isaacs in 1961; a total of five cas...

Continuous muscle fibre activity in an Indian male with additional evidence of terminal motor fibre abnormality.

Continuous muscle fibre activity in an Indian male with additional evidence of terminal motor fibre abnormality.