Fiber density in congenital muscle fiber type disproportion. II. Congenital muscle hypotonia and hip dislocation.

Our previous paper presenting electromyographic findings in patients with congenital fiber type disproportion myopathy, confirmed the myogenic character of the disease process. That group of patients was however fairly heterogenous regarding both the clinical features and the morphological changes in muscle fibers (e.g. cases with central cores). In the present study we have examined 13 children with hypotonia and muscle fiber type disproportion operated on in childhood for congenital hip dislocation. In all cases CNEMG and SFEMG with FD estimation was performed in biceps brachii and quadriceps femoris muscles. In all muscles examined either slight EMG changes indicative of myopathy or a normal EMG pattern was found. None of the patients demonstrated an evident increase in FD values. Normal FD and the recruitment pattern proportional to the force of contractures indicate that the normal number of motoneurons is preserved. Accordingly, our present findings confirm the conclusions of our previous paper.

Fiber density in congenital muscle fiber type disproportion. I. Congenital myopathies.

In 15 cases with congenital muscle fiber type disproportion, concentric needle EMG (CNEMG) and single fiber EMG (SFEMG) with fiber density (FD) estimation was performed. The aim of the work was to establish the nature of congenital muscle fiber type disproportion. In 11 cases CNEMG revealed interference pattern on maximal effort and low, polyphasic motor unit action potentials (MUAPs) of short duration indicating a myopathic lesion. In four other cases electromyographic changes were less evident. The FD values were slightly increased in 9 cases. This finding could be explained by pronounced muscle fiber splitting with subsequent ephaptic transmission or even secondary denervation and reinnervation. The most important conclusion from our pilot study is the confirmation of the fact that reinnervation with excessive sprouting is not the only mechanism responsible for muscle fiber type disproportion.

[Spinal cord tumors simulating the clinical course of Charcot-Marie disease]. / Guzy rdzenia imitujace przebiegiem klinicznym chorobe Charcot-Marie-tooth.

The authors describe two cases of extramedullary tumours in the vertebral canal with long (7 and 15 years) course without pains and with clinical manifestations simulating Charcot-Marie-Tooth disease. It is stressed in conclusion that sporadic cases of this disease with involvement of the lower extremities only, with normal conduction velocity in the peroneal nerves should be differentiated against spinal cord tumours situated in the vertebral canal.

Is Kugelberg-Welander spinal muscular atrophy a fetal defect?

Twelve children who had developed Kugelberg-Welander (K-W) spinal muscular atrophy (SMA) before the age of six years were investigated. Electrophysiological, histochemical, ultrastructural, and biochemical studies demonstrated features of immature muscle fibers suggesting a fetal defect as in the Werdnig-Hoffmann (W-H) form of SMA. Comparison with known patterns of human myogenesis and of experimental denervation of immature muscle suggested that the defect in K-W SMA probably takes place in fetal life at a stage later than in W-H SMA. In contrast to W-H SMA, a considerable percentage of mature fibers of normal structure and diameter were present. The immature fibers impair the normal development of muscle cells by preventing the increase in number of mature fibers and causing an overloading of the normal fibers with consequent hypertrophy and eventually destructive changes. This is the pattern in K-W disease that distinguishes the juvenile form of SMA from W-H disease.

Evaluation of results of thymectomy in myasthenia gravis.

The results of thymectomy carried out in 150 cases of myasthenia gravis are discussed. In a group of 123 cases followed for 1 to 5 years after the operation, full remission was observed in 24.4% of cases, significant improvement in 36.6%, slight improvement in 24.4% and no improvement in 8.1%, while deterioration occurred in 1.6% of patients. No correlation was found between the result of the operation and the age and sex of patients, but better results were achieved in those treated surgically rather soon after the onset of symptoms. This correlation was particularly evident in the group with full remissions. The results obtained in the cases without thymic tumors were better than in the cases with tumors. No correlation was noted between the results of the operation and the histological characteristics of the thymus in the group with thymic hyperplasia and in the group with thymic atrophy. The surgically treated group (150 cases), compared with the conservatively treated group (75 cases), showed the superiority of the surgical method (lower rate of death and deterioration, higher rate of improvement and remission). In discussing the indications for surgical treatment the authors emphasize that advances in anaesthesiology in recent years have reduced the risk of operation. It is suggested that the indications for surgical treatment should be expanded and operations should be performed as early as possible after the onset of clinical manifestations without regard to the age and sex of the patient. Operation should not be considered in cases belonging to group 1, 2a (sometimes 2b) only, with duration of the disease over 8-10 years and with little or no progression of the process, if the presence of a thymic tumor has been excluded.

Development of chequerboard pattern in human foetal skeletal muscle.

The study was undertaken to race the histochemical and electron microscopic development patterns of human myogenesis from the 9th to the 26th week of foetal life. Particular attention was paid to the possibility of appearance of metabolic or structural differences between individual skeletal muscle fibres in early periods of myogenesis. The 9th week of foetal life is the period when primitive myotubes are formed. Irregular distribution of the ATPase (pH 9-4) activity observed at this time is due to differences in the structure of fusing myoblasts. The early myotubes show a high activity of the oxidative enzymes and lack of phosphorylase. Conversion of immature muscle cells into structurally mature fibres begins between the 20th and the 24th week. The latter fibres exhibit a uniform activity of all the studied enzymes and thus resemble the intermediate type of fibres of mature muscles. From about the 26th week on the typical mosaic pattern of the enzymatic activity is observed. All the differences in enzymatic activity which appear in fibers prior to their full morphologicaal maturity result from differences in developmental stages of the fibres at the given moment. The present study also suggests that there are no morphological or metabolic differences between individual humanskeletal muscle fibres prior to their metabolic differentiation into types which occurs after their innervation.