Primary Muscle Disorders Research Articles

Congenital Muscular Dystrophies ‐Problems of Classification

The classification of congenital muscular dystrophies (CMD), based on perceived clinical and morphological similarities or differences, is controversial. CMD without cerebral involvement has sometimes been divided into a mild and a severe form. This distinction is, however, arbitrary and not uncontested. Whether Ullrich's disease, formerly called atonic-sclerotic dystrophy, is a disease entity and if so, whether it is a primary muscle disorder, is uncertain. CMD without cerebral involvement is inherited in an autosomal recessive fashion in the great majority of cases. CMDs with cerebral involvement are usually classified into at least three forms: the Fukuyama type of CMD, occurring almost exclusively in Japanese patients; CMD with hypomyelination, sometimes also called the occidental type of cerebromuscular dystrophy; and Walker-Warburg syndrome. Muscle-eye-brain disease, described in a number of Finnish patients, may or may not belong in this last category. In CMD with cerebral involvement inheritance is also autosomal recessive. It is possible that single sporadic cases are phenocopies due to infectious or other exogenous causes. Reports of clinical and morphological findings from an increasing number of patients show a high degree of variability within and, on the other hand, certain similarities between the forms of CMD with cerebral involvement. In addition, neuroradiological changes are also found with increasing frequency in CMD patients without clinical neuropsychological abnormalities. It is not unreasonable to speculate that molecular genetic techniques will reveal in the near future a variable defect in one gene locus or defects in a few gene loci as the cause of the various clinical forms of CMDs.

Adverse impact of interstitial pulmonary fibrosis on prognosis in polymyositis and dermatomyositis

Interstitial pulmonary fibrosis occurs in approximately 9% of patients with PM/DM, yet its effect on the course of PM/DM has been scarcely noted. In this report, two patients with PM/DM and IPF were presented to highlight the fact that pulmonary disease can overshadow the primary muscle disorder and progress despite therapy with corticosteroids and nonsteroidal immunosuppression. Our patients were added to previously reported cases and an overview of PM/DM and IPF was presented. Sixty-seven patients with the diagnosis of PM/DM and IPF, with a mean age of 60 ± 18 years, were identified. Pulmonary complaints were present in 64 cases. Fever was present in 18, arthritis or arthralgias in 11, and Raynaud's phenomenon in 9. Forty percent died after followup of 31 ± 32 months. This mortality was significantly higher ( P < .05) than that in 745 historical controls with PM/DM without IPF. Progressive IPF was the immediate cause of death in 58% of those who died. A subgroup of 29 patients who had histologic documentation of both myositis and IPF had a mortality of 62% after 22 ± 25 months. In this latter group, six patients had RP; five of these died. Patients who were not treated with corticosteroids also appeared to fare worse but, given the small number of patients involved, definite conclusions cannot be drawn. We conclude that patients with PM/DM can be adversely affected by the presence of IPF and that this negative impact may be exaggerated by RP and perhaps by lack of treatment. We believe that the mortality and morbidity in PM/DM and IPF is underappreciated and that early institution of intensive therapy is warranted in these cases, especially in patients with RP.

The significance of simultaneous estimation of serum creatine kinase and myoglobin in neuromuscular diseases.

Serum creatine kinase (CK) and myoglobin (Mb) levels were measured in patients with different neuromuscular diseases, carriers of X-linked Duchenne-type muscular dystrophy and normal volunteers. The highest levels were found in Duchenne dystrophy and both values decreased in parallel with age. In patients suffering from limb-girdle dystrophy the increases in CK activity and Mb concentration were also pronounced. However, there were families with normal and others with elevated CK and Mb levels in facioscapulohumeral dystrophy. In neurogenic atrophies both CK and Mb levels generally increased only slightly. Serum Mb and CK levels have similar values as indicators of muscle damage in primary and secondary skeletal muscle disorders. The serum Mb level helps in the detection of carriers but is not more sensitive than CK measurement.

Static spinal muscular atrophy causing temporomandibular joint dysfunction

A case of static spinal muscular atropy is described. The patient presented with temporomandibular joint dysfunction. This case is unusual, not only from the perspective of clinical disease progression, but also that markedly elevated creatine kinase levels were demonstrated. Despite an obvious association of neuromuscular disorders and TMJ disease, reports of primary disorders of muscle and nerve which may predispose to this condition are rare. This case emphasizes the need for careful neuromuscular evaluation in all patients with TMJ dysfunction of nonarticular origin.

Overuse syndrome in musicians--100 years ago. An historical review.

Overuse syndrome in musicians was extensively reported 100 years ago. The clinical features and results of treatment, which were recorded in considerable detail, match well the condition that is described today. The medical literature that is reviewed here extends from 1830 to 1911 and includes 21 books and 54 articles from the English language literature, apart from two exceptions; however, the writers of the day themselves reviewed French, German and Italian literature on the subject. The disorder was said to result from the overuse of the affected parts. Two theories of aetiology, not necessarily mutually exclusive, were argued. The central theory regarded the lesion as being in the central nervous system, the peripheral theory implied a primary muscle disorder. No serious case was put forward for a psychogenic origin, though emotional factors were believed to aggravate the condition. Advances in musical instrument manufacture--particularly the development of the concert piano and the clarinet--may have played a part in the prevalence of overuse syndrome in musicians. Total rest from the mechanical use of the hand was the only effective treatment recorded.

Evaluation of central and peripheral components of muscular fatigue in neuropathic and myopathic patients

In a group of patients chronically denervated and other with primary muscle involvement a search was made for mechanisms involved in the muscular fatigue. It was found that there was no major differences between patients chronically denervated and controls, while in those others with primary muscle disorders a loss of functional motor units during effort and a transient impairment of neuromuscular transmission play a role together with the central events normally occurring in fatigue.

Serum myoglobin in primary and secondary skeletal muscle disorders.

Serum myoglobin was measured by a sensitive radioimmunoassay in healthy controls and patients with primary and secondary skeletal muscle disorders. The results indicate that serum myoglobin is a useful parameter in the assessment of muscle damage.

Studies on the Pathophysiology of Infraspinatus Muscle Contracture in the Dog

Contracture of the infraspinatus muscle has been recognized as a cause of shoulder lameness in hunting dogs. Electrophysiologic studies of four affected dogs indicated that infraspinatus contracture was a primary muscle disorder rather than a neuropathy. Histologically, affected tissues from six dogs showed degeneration and atrophy of skeletal muscle with fibrous tissue replacement. These findings supported the hypothesis that an acute traumatic event caused incomplete rupture of the infraspinatus muscle, leading to fibrosis and contracture. Seven dogs were successfully treated by infraspinatus tenotomy.

Hypotheses and recent findings concerning aetiology and pathogenesis of the muscular dystrophies.

The survey reports recent findings and current hypotheses on the aetiology and pathogenesis of the muscular dystrophies. Briefly presented are (1) biochemical anomalies of structure and metabolism, (2) membrane defects, (3) the neural hypothesis, (4) the vascular hypothesis, and (5) the connective tissue hypothesis. At present, research interest is focused primarily on membrane structure and biochemistry, on neural muscle trophism, and on the genetic aspects of abnormalities in molecular biology. Whether the progressive muscular dystrophies are primary disorders of voluntary muscle or whether the primary alteration is located outside of the muscle still remains unknown.

Increased collagen synthesis in arthrogryposis multiplex congenita.

THE etiology and pathogenesis of arthrogryposis multiplex congenita (AMC) are not well understood. Most investigators accept the concept that the disease is a syndrome with different causes. These may be genetic1or environmental2and can be associated with neurological lesions of supranuclear structures3or of anterior horn cells,4,5primary muscle disorders,6,7or failure of muscle development (amyoplasia).8In an attempt to evolve a unified hypothesis, McKusick9proposed that several clinical features of AMC, such as changes in the joints or the skin and the occurrence of hernia, suggest a heritable disorder of connective tissue. Consistent with this view is the histopathological study of Hariga et al,10suggesting that an increase of fibrous tissue precedes muscle fiber degeneration. Nevertheless, there is a clear need for biochemical data to support this idea. As part of a broader study of protein synthesis in human

Scientific Aspects of Neurology

The communications presented at the Leeds Neurological Sciences Colloquium, 1959-1960, encompass an interesting group of subjects by the leaders in this specialty from Scotland and England, plus one foreign guest. The titles are as penetrating as the discussions. A new technique for the selection of sites for muscle biopsy, based upon the zone of maximum electrical excitability of the muscle, is described in the chapter, The Diagnostic Value of Motor Point Muscle Biopsy. A biopsy, performed at the appropriate site, includes one or more motor end-plates, with a portion of the axon. Harriman studied several neurogenic and primary muscle disorders with this technique. Broca's contribution to aphasia was reviewed by Critchley a century later. The significance of Broca's area has suffered considerably in the intervening years, according to Critehley, due to the confusion between localization of lesions and localization of function. Broca was less to blame than some of his