[Muscular fatigue in chronic respiratory insufficiency. Physiopathologic considerations and therapeutic strategies]

The Authors has performed a careful exam of the pattern of chronic airways insufficiency in children. They dwell on the reasons which determinate the increase of the inspiratory muscular load and of difficulty of inspiratory muscles. Continuing that exam, the chronic anoxia of muscular cells (a bioptic study) is correlated with functional troubles of muscular fibre. In addition to that the Authors subdivide several different illness of lung in children according to the different mechanism of respiratory insufficiency. They conclude with the exam of strategy to use to obtain the diminution of the muscular load and of respiratory insufficiency.

Stress in patients with pain in the muscles of mastication and the temporomandibular joints

This study examined the role of stress in subjects having combined muscle and temporomandibular joint pain compared to subjects having only muscle pain or only joint pain. It was found that the combined pain (n = 39) and muscle pain (n = 24) groups had comparable levels of pain intensity and activity impairment. The combined pain group, however, had the lowest level of stress and was rated lower than the muscle group in clinicians ratings of psychological factors, stress and chronicity. The combined pain group and joint pain group (n = 28) were found to be comparable in terms of the clinician's ratings. This data does not support the concept of a progression of symptoms from muscle pain to combined muscle and joint pain that would be expected from a stress-induced muscle hyperactivity model of temporomandibular disorders.

Schistosomiasis and nutritional myopathy in a Brazilian tapir (Tapirus terrestris)

Gross lesions suggestive of severe hepatoenteropathy and myopathy were noted in a 4.5-yr-old Brazilian tapir (Tapirus terrestris) from a zoo in Michigan (USA). The major microscopic lesions were granulomatous hepatitis and hemorrhagic enteritis associated with non-operculated eggs compatible with those of the Schistosomatidae (Digenea). Skeletal muscle and tongue contained foci of severe acute myodegeneration and necrosis. The hepatic vitamin E value of 1.3 ppm dry weight was considered critically low.

Lipid storage myopathy due to glutaric aciduria type II: treatment of a potentially fatal myopathy

Several patients with lipid storage myopathies have been described, although in most cases the biochemical defect is unclear. A child is reported who presented with severe muscle weakness at age six months. She had lipid storage myopathy due to glutaric aciduria type II. It is probable that her brother died from the same disorder at the age of three months. She has responded well to treatment with a low-fat diet, riboflavin, carnitine and glycine.

Burn injury to trunk of rat causes denervation-like responses in the gastrocnemius muscle

Thermal injury results in dystropic changes in skeletal muscle and abnormal pharmacological responses to neuromuscular relaxants, each of which suggests a denervation-like phenomenon. In the rat thermal injury model we examined whether, as in denervation states, increases in nicotinic acetylcholine receptors (AChR) and hyposensitivity to d-tubocurarine (dTc) are found. While anesthetized, thermal injury was imposed to trunk only. At 10, 14, and 21 days after injury the effective doses of dTc for left gastrocnemius tension suppression to 95% of control tension (ED95) were 0.213 +/- 0.039, 0.305 +/- 0.070, and 0.214 +/- 0.032 mg/kg, respectively. These values were significantly higher (P less than 0.05) than control values (0.155 +/- 0.006 mg/kg). The AChR concentrations in the left gastrocnemius, quantitated by 125I-alpha-bungarotoxin binding, increased at 10, 14, and 21 days to 182 +/- 20% (P less than 0.001), 166 +/- 22% (P less than 0.03), and 164 +/- 18% (P less than 0.001) of control, respectively. AChR concentrations in the right gastrocnemius also increased subsequent to thermal injury. Changes in effective dose of dTc for 50 and 95% twitch suppression in the left gastrocnemius correlated significantly with changes in AChR concentrations for the same muscle (r = 0.73 and 0.81, P less than 0.001, respectively). This study confirms the hypothesis that the systemic effects of thermal injury include an increase in AChR at sites distant from thermal injury, which may account for the skeletal muscle dysfunction and aberrant responses to neuromuscular relaxants.

Myopathy with unique ultrastructural feature in Marinesco-Sjögren syndrome

We have investigated 3 children aged 6, 3, and 2 years, from 2 families, with the clinical features of Marinesco-Sjögren syndrome. Muscle biopsy specimens from all 3 were abnormal and showed small vacuoles and slight variation in fiber size. Electron microscopy revealed vacuolation and membranous whorls and, in particular, a unique dense membranous structure associated with nuclei. These cases emphasize the involvement of muscle in Marinesco-Sjögren syndrome and the importance of electron microscopy in differential diagnosis.

Extensive defects of mitochondrial electron-transfer chain in muscular cytochrome c oxidase deficiency

This study was undertaken to estimate the extent of molecular defects in the mitochondrial electron-transfer chain of a patient with mitochondrial myopathy. Biochemical and immunochemical studies were performed on the skeletal muscle mitochondria. Spectrophotometry and enzyme activity measurements localized a definite defect at the segment of cytochrome c oxidase (complex IV) of the electron-transfer chain. Immunoblotting and immunoprecipitation studies using the anti-complex IV antibody revealed that the contents of subunits 1, 4, 5, 6, and 7 of complex IV were markedly diminished and that subunit 2 was almost absent. Immunohistochemistry of the muscle tissue revealed a considerable accumulation of immunoreactive materials of complex IV in the ragged-red fibers. The immunoblots using the anti-NADH-ubiquinone oxidoreductase antibody demonstrated that the contents of NADH-ubiquinone oxidoreductase subunits were 47% of control and that the contents of three subunits were considerably decreased. The contents of ubiquinol-cytochrome c oxidoreductase subunits were also somewhat low (77% of control) and one of the minor contaminants detected in the control was completely absent. High-resolution one-dimensional sodium dodecyl sulfate-urea-gel electrophoresis disclosed that six additional unidentified polypeptides in the control were markedly diminished or completely missing. These results demonstrate that the molecular defects in the mitochondrial electron-transfer chain are more extensive than would be expected from either spectral analysis or enzyme activity measurements alone, and involve not only complex IV but also NADH-ubiquinone oxidoreductase and ubiquinol-cytochrome c oxidoreductase and several unidentified mitochondrial proteins.

Computed tomography demonstration of unusual diffuse metastatic calcification secondary to renal failure

We report the computed tomography findings in an unusual case of diffuse metastatic calcification secondary to renal failure.

Scapuloperoneal neuropathy: a distinct clinicopathologic entity

Peripheral neuropathy as a cause for the scapuloperoneal syndrome continues to be controversial. This report provides further evidence in support of a scapuloperoneal neuropathy as a separate nosologic entity. Three men had a slowly progressive disorder of 5-17 years duration with prominent weakness and atrophy of scapular stabilizer, shoulder girdle and distal lower extremity muscles accompanied by a distal pan-modality sensory loss. Electrodiagnostic studies and sural nerve biopsies indicated a primary axonal neuropathy with secondary demyelination and remyelination.

Aeromonas hydrophila septicaemia and muscle abscesses associated with immunosuppression

We report a case of septicaemia and muscle abscesses due to Aeromonas hydrophila. The patient was immunosuppressed due to Hodgkin's disease and treatment with cytotoxic chemotherapy. The abscesses resolved after prolonged antibiotic therapy. Organisms that were once considered rarely pathogenic are emerging as increasingly important in causing potentially lethal infections in immunosuppressed patients.

Investigation of serum creatine kinase variability after muscle-damaging exercise

1. The present study examined if the presence of creatine kinase (CK) inhibitors might explain the large variability in blood levels of CK among subjects after exercise-induced muscle damage. 2. Twenty-four women performed an eccentric exercise with the forearm flexors and were then classified as no CK responders, low CK responders and high CK responders. High CK responders repeated the exercise two weeks later (bout two). 3. Sera from high CK responders were mixed with sera from no CK responders or low CK responders. Also, serum from high CK responders obtained after bout one was mixed with the same subject's serum from after bout two. 4. In all cases, the differences between the expected and observed CK activity for the mixes were within the expected variability for the assay. 5. Although CK inhibitors have been previously observed in sera from patients with muscle injury or disease, we were unable to demonstrate the presence of CK inhibitors in the sera from subjects who showed evidence of exercise-induced muscle damage.

Lumbosacral hyperlordosis due to fibrosis of the paravertebral muscles. Case report

The authors present a case of lumbosacral hyperlordosis due to primary fibrosis of the paravertebral muscles. This very rare lesion in described and the surgical treatment used in this case is illustrated. The clinical and cosmetic results were both excellent.

Reversible cerebral segmental vasoconstriction

Vasoconstriction is not recognized as a cause of cerebrovascular disease except in the vasospasm seen following subarachnoid hemorrhage and possibly in migraine. However, we found four patients to have transient, fully reversible vasoconstriction and dilatation prominently involving arteries around the circle of Willis. All four patients were evaluated for severe headaches and fluctuating or recurring motor or sensory deficits. No cause for the clinical syndromes and angiographic abnormalities was found. Similar patients are reported in the literature under various nosologies. This newly recognized clinical-angiographic syndrome should be differentiated from other known causes of vessel constriction and dilatation; the precipitants of reversible vasoconstriction may then be better defined.

Poststernotomy infections presenting as deep neck abscess

A review of the world literature has failed to reveal any published reports of poststernotomy mediastinitis presenting as a deep neck infection. This article presents two such cases. Since the fascial layers of the mediastinum are a direct continuation of the cervical fascia, a number of potential pathways between the neck and mediastinum exist. Descending infection from the neck into the mediastinum is well documented. The reverse situation, an ascending infection from the mediastinum into the neck, is not described despite the potential natural pathways available for spread of infection. Our proposed mechanism for these two cases is that a surgically created pathway from the mediastinum to the lower neck allows for mediastinitis to point in the intercommunicating fascial spaces of the neck. Recognition of this clinical presentation will allow the surgeon to use prompt intervention for such a serious complication.

Endocrine myopathies

The atrophy produced by endocrine disorders is primarily due to alterations in protein and carbohydrate metabolism. Type II muscle fibers are more severely affected than are Type I fibers. Steroid myopathy and the myopathy associated with excess ACTH have a typical pattern of proximal weakness affecting the legs more than the arms. Steroid myopathy is usually not apparent until other signs of glucocorticoid excess are present. Treatments of steroid myopathy are as follows: Lower the dose of steroid, use a nonfluorinated glucocorticoid, and exercise or physical therapy. Adrenal insufficiency produces generalized weakness, muscle cramping, and fatigue in 50 per cent of patients. Some patients also develop hyperkalemic paralysis. The treatment is hormone replacement. Thyrotoxicosis produces myopathy caused by net protein catabolism, accelerated basal metabolic rate and impaired carbohydrate metabolism. Shortening of contraction time may result from accelerated myosin ATPase activity and enhanced calcium uptake by the sarcoplasmic reticulum. Depolarization of the muscle fiber and impaired Na-K activity in muscle may predispose to thyrotoxic periodic paralysis. Neuromuscular presynaptic impairment may account for the worsening of myasthenia gravis by thyrotoxicosis. In hypothyroidism, impaired energy metabolism may limit force generation. Slow contraction and relaxation reflect reduction in myosin ATPase activity and impaired calcium uptake by the sarcoplasmic reticulum. Treatment for thyroid-associated muscle disorders is restoration of a euthyroid state. Muscle weakness associated with hypopituitarism is due to loss of thyroid and adrenal cortical hormones. Children require growth hormone for muscle development. T3 and growth hormone synergize to maintain normal protein synthesis. Primary and secondary hyperparathyroidism and osteomalacia are often associated with proximal weakness and fatigability. The myopathy improves with restoration of normal PTH levels and vitamin D replacement. Hypoparathyroidism and pseudohypothyroidism are associated with tetany. Tetany is worsened by alkalosis and is treated by calcium and magnesium replacement.

Myopathies caused by disorders of lipid metabolism

Myopathies due to abnormalities in fatty acid oxidation fall into several clinical categories. Rhabdomyolysis occurring with prolonged stress on the muscle is frequently found to be caused by carnitine palmityl transferase deficiency. The association of systemic metabolic derangements and muscle weakness is seen with defects in long-chain acyl-CoA dehydrogenase, medium-chain acyl-CoA dehydrogenase, or short-chain acyl-CoA dehydrogenase. The latter three are often associated with low muscle carnitine concentrations. In patients who present with only muscle weakness and triglyceride storage, muscle carnitine concentrations may be either normal or reduced.

Myalgia

Myalgia, a common symptom resulting from a variety of disease processes, often escapes a specific etiologic diagnosis. Despite the poorly understood pathogenetic mechanisms underlying myalgia, logical classification and clinical evaluation can lead to successful treatment in many cases.

The postpolio syndrome. An overuse phenomenon

Persons with good recovery of function following their initial poliomyelitis are now, more than 30 years later, experiencing new weakness, fatigue, and muscle pain. The likelihood of muscle overuse being the cause of this late functional loss was investigated by dynamic electromyography (EMG) and foot-switch stride analysis in 34 symptomatic patients. Manual testing grouped the muscles, with strong (S) encompassing Grades Good (G) and Normal (N) while weak (W) included Fair plus (F+) to zero (0). After testing quadriceps and calf strength, the patients fell into one of four classes: strong quadriceps and calf (SQ/SC), strong quadriceps and weak calf (SQ/WC), weak quadriceps and strong calf (WQ/SC), or combined weak quadriceps and calf (WQ/WC). Quantified EMG (normalized by the manual muscle test EMG) defined the mean duration and intensity of the quadriceps, soleus, lower gluteus maximus, and long head of the biceps femoris during walking. Overuse was defined as values greater than the laboratory normal (mean + 1 SD). Each muscle exhibited instances of overuse, normalcy, and sparing. The biceps femoris was the only muscle with dominant overuse (82%). Quadriceps overuse was next in frequency (53%). Soleus activity infrequently exceeded normal function (34%), but this still represented more than twice the intensity and duration of the other muscles. Gluteus maximus action was also seldom excessive (34%). The patients averaged two muscles with excessive use during walking. Gait velocity of the SQ/SC strong group was highest (71% of normal) while the three categories that included weak muscles had walking speeds in the range of 50% of normal. The finding of muscle overuse during a single free-speed walking test that does not attain normal velocity supports the concept of muscle overuse being the cause of the patient's dysfunction.

[A case of pseudo-Bartter's syndrome associated with hypokalemic myopathy]

A case of pseudo-Bartter's syndrome associated with hypokalemic myopathy was presented. A 37-year-old housewife was admitted to our hospital because of muscle cramps with muscle weakness and tetany. There was a history of facial edema and constipation, which have been managed with "Kanpo medicine (Chinese medicine)" and laxatives for several years. The patient was amenorrhea 3 months before entry. She began to experience muscle weakness and muscle cramps associated with gait disturbance 2 or 3 months before admission. On physical examination, she was thin with positive Trousseau's and Chvostek's signs. Laboratory studies revealed hypokalemia, low urinary excretion of potassium, hypocalcemia, metabolic alkalosis, elevated creatine phosphokinase (CPK), increased levels of plasma renin activity and plasma aldosterone concentration, and decreased sensitivity to pressor effect of angiotensin II. Potassium supplementation resulted in restoration of her symptoms and normalization of low serum calcium and elevated CPK levels. She was diagnosed to be pseudo-Bartter's syndrome due to anorexia nervosa. The mechanism(s) of hypokalemia in our case was discussed.