Glycogenosis type V (McArdle's disease) mimicking atypical myositis.

A 13-year-old girl was referred to our clinic because of a positive rheumatoid factor test, muscle pain and weakness. Laboratory evaluation revealed an increased ESR, hypergammaglobulinaemia, antinuclear antibodies, circulating immune complexes, complement consumption and elevated serum creatine kinase (CK) activity. A needle biopsy of the dolent muscle showed normal routine histology. Immunohistochemistry disclosed single lymphocytes and a weak myocytic HLA class I expression. The diagnosis of myositis was considered and corticosteroids were initiated, leading to an increase of complement levels and a decrease of CK-activity and ESR. She subjectively felt stronger but still reported exercise intolerance and metabolic myopathy was considered. Myophosphorylase activity was completely lacking, establishing the diagnosis of McArdle's disease. CK level was found to be elevated in an obese 4-year-old brother too, who refused extensive walking but reported no muscle pain. Myophosphorylase deficiency was demonstrated by histochemistry and by biochemical analysis of his muscle. The female case illustrates that in children with the clinical picture of inflammatory myopathy and serological but not clinical response to therapy underlying metabolic muscle disorders should be excluded. Since the pathogenesis of polymyositis remains unclear, we speculate that inflammatory changes observed in the muscles may have been initiated by muscular damage resulting from the underlying metabolic disease. The serological changes remained unexplained and may contribute to a so far undeterminable connective tissue disease.

Therapy of complex I deficiency: peripheral neuropathy during dichloroacetate therapy.

A therapeutic trial with polyvitamins and dichloroacetate (DCA) in combination with thiamine in a 13-year-old girl with complex I deficiency is reported. The polyvitamin therapy included thiamine, riboflavin, ascorbate, coenzyme Q 10 and carnitine. This therapeutic regine was used over a period of 17 months without any effect. Although DCA lowered the lactate concentration in blood and CNS--measured by magnetic resonance spectroscopy--no clinical benefit was achieved. After 20 weeks of DCA therapy a distal polyneuropathy with areflexia developed although 100 mg thiamine daily as comedication was given from the beginning of DCA therapy. Nerve conduction velocity of the peroneal nerve was not detectable, sensible evoked potentials of the tibialis posterious nerve were normal. This side-effect resolved completely within 6 months after omission of DCA. Our observation suggests a direct toxic effect of DCA only on the peripheral nervous system in our patient since several cerebral MRI and magnetic resonance spectroscopy studies showed no abnormalities. CONCLUSION. DCA lowers the lactate concentration in children with complex I deficiency of the respiratory chain in a dose of 100 mg/kg body weight without clinical benefit. Reversible peripheral polyneuropathy may develop under DCA therapy despite thiamine medication.

Deficiency in complex IV (cytochrome c oxidase) of the respiratory chain, presenting as a leukodystrophy in two siblings with Leigh syndrome.

Two siblings with Leigh syndrome presenting at the age of 6 months with clinical and radiological features suggestive of a leukodystrophy are reported. A deficiency in complex IV of the respiratory chain (cytochrome c oxidase) was demonstrated in muscle mitochondria of both patients. To our knowledge, this is the first familial case of Leigh syndrome due to cytochrome c oxidase deficiency, presenting clinically and radiologically with signs of a leukodystrophic process. We suggest that respiratory chain enzyme defects should be considered in the differential diagnosis of cases suggestive of a leukodystrophy.

[Myoglobinuria and carnitine palmitoyltransferase deficiency. Diagnostic procedure and differential diagnosis]. / Myoglobinurie und Carnitinpalmityltransferase-Mangel. Diagnostisches Vorgehen und Differentialdiagnosen.

Carnitine palmitoyltransferase (CPT) deficiency is the most common metabolic cause of recurrent myoglobinuria. We describe five patients with CPT deficiency who were recruited during a 24-months period. Phenotypic expression ranged from mild myalgia without myoglobinuria to severe exercise-induced attacks and a lethal course. The pathophysiological basis of the clinical heterogeneity is discussed. The diagnostic procedure includes a neurological and electromyographical examination as well as an exercise test and extensive biochemical investigations of muscle biopsy specimens. Accurate diagnosis allows an early introduction of preventive measures and clearly improves the outcome.

Multiple respiratory chain abnormalities associated with hypertrophic cardiomyopathy and 3-methylglutaconic aciduria.

In a 4.5-month-old boy presenting with marked muscular hypotonia in the neonatal period, hepatomegaly, cardiac hypertrophy, recurrent hypoglycemia, metabolic acidosis, and secondary carnitine deficiency, there was a considerable urinary excretion of 3-methylglutaconic and 3-methylglutaric acid. Estimation of 3-methylglutaconyl-CoA hydratase, 3-hydroxy-3-methylglutaryl-CoA lyase and initial enzymatic steps of cholesterol biosynthesis in cultured fibroblasts and in different tissues postmortem revealed no enzyme deficiency. Analyses of the respiratory chain in postmortem tissues demonstrated severe impairment of complex I (NADH ubiquinone oxidoreductase) and complex IV (cytochrome c oxidase) activities in skeletal muscle and reduced complex IV activity in heart.

Skeletal muscle sonography: a correlative study of echogenicity and morphology.

In skeletal muscle sonography high echogenicities have proved to be of diagnostic value. The following study examines whether these echointensities are caused mainly by interstitial fat or fibrosis. Consequently, the echogenicities of 86 muscles, their diameters, and the thickness of subcutaneous fat layers superficial to these muscles were measured and compared for content of fat and connective tissue, which were assessed by morphometry and biochemical testing in the corresponding muscle biopsy samples. The results indicate that fat replacement constitutes the main cause of increased muscle echogenicity, whereas intramuscular fibrosis did not significantly affect the muscles' echogenicity.

Generalized mitochondrial microangiopathy and vascular cytochrome c oxidase deficiency. Occurrence in a case of MELAS syndrome with mitochondrial cardiomyopathy-myopathy and combined complex I/IV deficiency.

The pathophysiological significance of the mitochondrial microangiopathy in MELAS (mitochondrial encephalopathy, lactic acidosis, and strokelike episodes) syndrome was evaluated in an autopsy study of a nearly 13-year-old girl who had suffered from multiple infarctlike lesions in the brain, a mitochondrial myopathy-cardiomyopathy, and a generalized mitochondrial microangiopathy. Cytochemically, defects of cytochrome c oxidase (complex IV) were visualized by light and electron microscopy in the skeletal and heart muscle and in the altered vessels, as well as in single bile duct cells, with the activity of the hepatocytes being diffusely reduced, whereas in the brain, the cytochemical activity was only slightly diminished. Biochemical studies revealed a 50% reduction of both NADH (the reduced from of nicotinamide-adenine dinucleotide) dehydrogenase (complex I) and complex IV in the skeletal muscle. In the brain, complex I was diminished to 20%, whereas complex IV was only slightly below the low-normal range. Immunohistochemical studies with the use of subunit-specific antiserum samples against cytochrome c oxidase showed a varying protein profile, with loss of both mitochondrially and nuclearly derived subunits being most pronounced in the heart muscle and lesser in the skeletal muscle. In the brain, liver, bile ducts, and especially the vessels, no loss of enzyme protein content was observed. The results illustrate heterogeneous tissue expression of respiratory chain defects in MELAS syndrome and indicate that vascular cytochrome c oxidase deficiency may be involved in the cerebral manifestation of the disease, whereas in other organs like the heart, a similar pathogenetic importance of the microangiopathy cannot be verified.

Type 2a fibre rhabdomyolysis in myoadenylate deaminase deficiency.

A 31-year-old woman developed an acute, potentially fatal rhabdomyolysis of undetermined origin. Muscle biopsy revealed selective lysis involving exclusively type 2a fibers. Myoadenylate-deaminase (MAD) deficiency was proven by a negative histochemical reaction as well as by an enzymatic biochemical determination. The significantly greater energetic dependence of type 2a fibres on MAD explains their selective damage. The patient's mother also suffers from a similar muscle disease of still unclarified origin.

Fatal infantile mitochondrial cardiomyopathy and myopathy with heterogeneous tissue expression of combined respiratory chain deficiencies.

A 5-month-old boy died of progressive heart failure that started at the age of 3 months. Autopsy revealed a mitochondrial cardiomyopathy and a mitochondrial myopathy of the limb muscle and diaphragm. Cytochemically random defects of cytochrome c oxidase were visualized by light and electron microscopy in the diaphragm and especially the heart muscle, the limb muscle showing a diffuse attenuation whereas the liver and kidneys reacted normally. The activities of NADH-dehydrogenase (complex I) and cytochrome c oxidase (complex IV) were severely diminished (20% residual activity of controls) in the skeletal and heart muscle. In the heart, succinate cytochrome c reductase (complex II/III) was additionally decreased to the same degree. Loss of cytochrome c oxidase activity was based on a reduction of both mitochondrial and nuclear derived subunits in the heart and diaphragm as revealed by immunohistochemical analysis, whereas the limb muscle showed a normal immunoreactive protein content. The results illustrate heterogeneous tissue expression of respiratory chain enzyme defects and demonstrate that a cardiomyopathy may be the leading presentation of a mitochondrial disorder in early infancy.

Myoadenylate deaminase deficiency: successful symptomatic therapy by high dose oral administration of ribose.

A 55 years old patient suffering from exercise-induced muscle pain and stiffness due to primary myoadenylate deaminase deficiency has been successfully treated with D-ribose since 1984: single doses of 4 grams administered at the beginning of exercise prevented the symptoms completely; on continuation of exercise this dose had to be repeated all 10-30 min. Total doses of 50-60 g per day were tolerated without side-effects.

Mitochondrial myopathy with diffuse activation and focal deficiency of mitochondrial ATPase and carnitine deficiency.

In skeletal muscle from a patient with a mitochondrial myopathy and muscular carnitine deficiency, histochemical analysis demonstrated that mitochondrial ATPase showed activation with loss of latency even before addition of the uncoupler dinitrophenol (DNP). According to combined histochemical and biochemical studies by Meijer and Vloedman (1980), this finding indicates loosely coupled oxidative phosphorylation. After the addition of DNP the reaction intensity was markedly increased, but there were scattered enzyme-deficient fibres in which some residual activity was shown by ultracytochemistry. No defect in mitochondrial enzymes was found in biochemical studies. The enzyme histochemical changes and carnitine deficiency are probably both secondary to an unknown mitochondrial defect. Both the carnitine deficiency and the mitochondrial myopathy remained unchanged following long-term carnitine substitution therapy despite clinical improvement.

[Diagnostic significance of muscle biopsies in metabolic myopathies. I. Myopathology]. / Diagnostische Bedeutung von Muskelbiopsien bei metabolischen Myopathien. I. Myopathologie.

The clinical course of metabolic myopathies is dominated by progressive muscle weakness and wasting or aching contraction and recurrent rhabdomyolysis with intense exercise. Vacuolar muscle fibre degeneration is the leading pathological finding on routine histological examination. For further characterization of those histologically empty looking vacuoles, histochemistry and electron microscopy are employed. Increase of glycogen, lipid droplets or mitochondria can often be demonstrated and indicate the need for subsequent biochemical identification of the underlying metabolic defect. Some other metabolic myopathies that cause recurrent rhabdomyolysis lack myopathological abnormalities. These can only be diagnosed biochemically, but additional new histochemical screening methods might be helpful.

[Diagnostic significance of muscle biopsies in metabolic myopathies. II. Clinical biochemistry]. / Diagnostische Bedeutung von Muskelbiopsien bei metabolischen Myopathien. II. Klinische Biochemie.

In the diagnosis of metabolic myopathies the use of biochemical methods, in addition to morphological examination of muscle biopsies, is often necessary in order to identify a specific metabolic defect. In order to narrow down the spectrum of biochemical methods, extensive clinical investigation and morphological examination, including histology, enzyme histochemistry and electromicroscopy if necessary have to be done beforehand. Patients are classified in the following groups: 1) progressive muscular weakness and/or muscle wasting with storage of a) glycogen, b) lipid or c) mitochondrial alterations; 2) recurrent rhabdomyolysis induced by fasting or exercise a) with glycogen storage or b) without any specific morphological alterations. The spectrum of metabolic defects comprises disorders of glycogen and glucose metabolism (deficiency of acid maltase, debranching and branching enzyme, phosphorylase, phosphofructokinase and other glycolytic enzymes), lipid metabolism (carnitine deficiency, carnitine palmitoyl transferase deficiency), mitochondria (respiratory chain disorders, pyruvate dehydrogenase deficiency) and others such as adenylate deaminase deficiency. In some of these e.g. infantile acid maltase deficiency and mitochondriopathies, it is clinically more important when organs other than muscle are affected; however, muscle biopsy is a useful substrate for diagnosis of these metabolic disorders.

Studies on the interference by haemoglobin in the determination of bilirubin.

Haemoglobin interference in the determination of bilirubin was compared in 7 different methods using the Jendrassik-Grof procedure, the Jendrassik-Grof-Nosslin modification, and the more recent procedures using nitrophenyldiazonium, 2,5-dichlorophenyldiazonium, 2,4-dichloraniline, and a direct reading method. To a variable degree, haemoglobin decreased the apparent absorption of the reaction product in all procedures. The extent of this decrease depended on the reagent used, the wavelength, incubation time, bilirubin concentration and the type of blank used. In an attempt to elucidate the mechanism of interference, haemoglobin was found to destroy the bilirubin diazo-compound whereas haemoglobin was ineffective. Likewise, storage of haemolytic samples for several days led to a disappearance of haemoglobin. H2O2, which had no effect in the absence of haemoglobin, potentiated the action of haemoglobin on diazobilirubin coupling. From our observations it can be concluded that haemoglobin disturbs the diazo-bilirubin reaction by a dual mechanism. H2O2, formed from oxyhaemoglobin by autoxidation, destroys the diazo bilirubin colour. In accordance with this explanation, potassium iodide stabilized the diazo compound against the peroxidative effect of oxyhaemoglobin; stabilization was not effective with superoxide dismutase, mannitol or ascorbate.