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In this study we present a patient with Canavan disease or Van Bogaert and Bertrand type of spongiform leukodystrophy, proven by brain biopsy. We performed morphological studies and biochemical assays on fresh homogenates of the grey and white matter. Quantitative neuromorphological analysis of the cortex showed normal values except for poor dendritic arborization of the inner layers. No signs of neuronal damage were observed. The Na-K-ATPase activity was increased. Pyruvate and ketone bodies oxidation rates and the activity of cytochrome-c oxidase were normal. We conclude that there is neither a primary neuronal damage nor a primary mitochondrial dysfunction in the oxidative processes despite the abnormal morphology of mitochondria in this disease.

A 20-year-old man with the characteristic findings of infantile onset Kearns syndrome is described. Morphological and biochemical investigations proved a mitochondrial disease which we believe to be the cause of the symptoms in various organs. We assume an autosomal-dominant inheritance, the marker sign of which is blepharoptosis in several family members. Characteristic clinical, morphological and biochemical findings, combined with an autosomal-dominant inheritance with very variable expression, mark the Kearns syndrome as an individual disease, not as a symptom complex (syndrome). Kearns disease can be divided into three forms--an infantile form ("Kearns-Sayre syndrome') with early onset, rapid progression, multisystemic involvement and a severe course; and a juvenile and an adult form with onset in the second, respectively third (or later) decades with a generally slower and more benign course and less widespread expression in various organ systems. Furthermore, the occurrence of a curious orthoptic abnormality is described, indicating one of the possible ways to avoid diplopia in chronic progressive external ophthalmoplegia: the coexistence of normal and gliding abnormal retinal correspondence.

Three patients from a large pedigree are described who had autosomal dominant spinal muscular atrophy that became manifest between the end of the fourth and the sixth decade. The disease progressed rapidly without evidence of corticospinal tract dysfunction, and within 3 years the patients died from respiratory failure.

In connection with 4 new cases of Kearns syndrome (multisystem form of mitochondrial CPEO), the condition was found to be present in slight to oligosymptomatic form in all 4 families. The marker symptom in subclinical patients was nearly always ptosis (sometimes very slight) and occasionally diabetes. In the literature other endocrine disorders, retinal anomalies, deafness, growth disturbances, etc., have been noted as subclinical symptoms in former generations. Heredity appears to be autosomal dominant in these 4 families, with very variable expressivity. The possibility that one gene is responsible for the disease seems to be plausible, but the marked variation in expressivity suggests a modifying influence of other alleles; in this sense, therefore, one may speak of multifactor inheritance. Supporting facts could also be found in the literature, where there was autosomal dominant heredity of the disease-carrying gene, but for its complete expression 'amplifying' factors (alleles) were needed. The pleiotropia of the disease-carrying gene is explained by a mitochondrial disorder of various organs. On the basis of the heredity, therefore, Kearns syndrome is not a syndrome but a disease. The most serious, most progressive and most extensive (multisystem) variant of Kearns disease is the infantile form, known as the 'Kearns-Sayre syndrome. When the expressivity of the disease is less extensive it usually occurs later in life and is less progressive: the adult form of Kearns disease.

Morphological and biochemical findings are described from the brain biopsy of an 11-year-old girl with intractable type II epilepsia partialis continua. Computerized tomography scan showed severe progressive central and cortical atrophy, mainly of the right hemisphere. Brain biopsy revealed microangiopathy of the cortex-penetrating arteries, patchy necrosis of the cortex, and small loose infiltrates of lymphocytic cells. Biochemical analysis showed normal pyruvate metabolism and citric acid cycle in gray and white matter.

Some clinical variants of oculopharyngeal dystrophy are known; a rare form is described in this article: the early-adult form of oculopharyngodistal myopathy. The diagnosis was made in 2 patients ((brother and sister) on the grounds of extensive clinical, biochemical and morphological (microscopical, histochemical and submicroscopical) investigations. Although oculopharyngeal dystrophy is generally considered to be a purely myogenic condition, in one of our patients some neurogenic indications were found (EMG and biopsy). The general picture, however, was that of a myopathy with the characteristic morphological signs of oculopharyngeal dystrophy in the skeletal musclebiopsy.

A patient with Friedreich's disease and chronic progressive external ophthalmoplegia is descirbed. An investigation was performed into the nature of the ocular motor disorders, which appeared clinically to be supranuclear. The EMG of the ocular muscles suggested myopathy. A specimen of ocular muscle was obtained by biopsy and examined with the light microscope and-for the first time-under the electron microscope. Signs of mitochondrial myopathy were found alongside neurogenic features. Postmortem examination of the central nervous system confirmed the diagnosis of Friedreich's disease with lesions of the motor cells in the anterior horn of the spinal cord. No evidence was found for a supranuclear or inernuclear origin of the ocular palsies, but 20-30 per cent of the neutrons in the nuclei III and IV were atrophic. Lesions of the non-medullated motor nerve fibres were also visible under the electron microscope. That the origin of the c. p. e. o. in this heredo-ataxia is neurogenic-nuclear is postulated on the grounds of the neuropathological and electronmicroscopic findings. Resemblances to the microscopic and submicroscopic and submicroscopic appearance of many types of "ocular myopathy" and "ophthalmoplegia-plus" throw doubt upon the myogenic character of these conditions. Possibly chronic, slowly progressive atrophy in the nuclear areas of the ocular motor nerves must in these cases also be held responsible for the c. p. e. o. Perhaps Moebius's Kern-Schwund theory may be revived after 85 years.

Four children with congenital fibre type disproportion were described. It was shown that their type 1 fibres were at least 12% smaller than the type 11 fibres. There was no increase in the terminal innervation ratio (TIR), but a decreased number of terminal knobs was observed in the biopsy of one child. The distribution of fibre types in the biopsy of another child bears out the notion that the abnormalities as seen in the biopsy can be traced back to the spine.

Myophosphorylase deficiency (McArdle's syndrome) is an uncommon condition characterized by exercise intolerance, muscle cramps and myoglobinuria. The present report describes the clinical, histochemical, electronmicroscopic and biochemical findings in a 12-year-old boy with myophosphorylase deficiency. The diagnosis should have been suspected when the boy was 6 years old. Most index cases have not been diagnosed until adult life, but this syndrome has to be considered in the differential diagnosis of exercise intolerance in childhood.

The results of a qualitative and quantitative neuromorphological and a biochemical analysis of a brain biopsy from a 7-year-old boy with an idiopathic type of Lennox-Gastaut syndrome (LGS) are reported. A disturbance in cerebral energy metabolism as expressed by the pyruvate pathway could be ruled out. Degenerative or ischemic lesions were not found. However, while the outer layers of the cortex were morphologically normal, the neurons of the inner layers (V and VI) showed a poor dendritic arborization and a diminished number of spines, which can be considered the basis of excessive excitability which in turn may further impair brain development. Thus, the neuromorphological findings suggest a causal rather then a consequential relation to LGS.

A boy presented suffering from generalised weakness, exercise intolerance and lactic acidosis. The weakness became evident at 2 years. A cerebral CT-scan showed cerebellar atrophy and central and peripheral atrophy of both hemispheres. With trichrome staining about 20% of the muscle fibres showed large areas containing red-staining granular material. Electron microscopic examination showed that this material consisted of areas of mitochondrial proliferation, most of the mitochondria having abnormal ultrastructural characteristics. Pyruvate dehydrogenase complex and citric acid cycle activities were determined by measuring 14CO2 production from various labelled substrates. Diminished oxidation rates were found with the patient's muscle homogenate for all substrates tested, indicating a defect in the respiratory chain. The cytochromes were present in normal quantities. Succinate cytochrome c reductase activity was very decreased. Carnitine concentration was decreased in serum and in muscle as well.

We present two unrelated patients, a boy and a girl, with a progressive neurologic disorder, characterized by psychomotor retardation, seizures and paresis, the illness being exacerbated during stressful periods. Lactate levels in serum and cerebrospinal fluid were elevated in both patients. Histopathologic studies of muscle tissue revealed mitochondrial abnormalities in the boy; in the girl, slight neuronal degeneration was observed. A cerebral biopsy in the girl showed abnormalities compatible with progressive poliodystrophy. Autopsy in the boy demonstrated progressive poliodystrophy. Biochemical studies in muscle tissue showed a defect of cytochrome aa3 in both patients, connected with a defect of cytochrome b in the girl. The association of defective pyruvate metabolism and progressive poliodystrophy is discussed.

We will present 8 children with progressive infantile or juvenile poliodystrophy (Alpers' disease), associated with a defect in pyruvate metabolism. Laboratory studies showed elevated levels of lactate in CSF and, in 4 children, elevated levels in serum. Histopathologic studies revealed lipid storage in liver and/or muscle tissue, sometimes myopathy with abnormal mitochondria and slight axonal degeneration in the peripheral nerve. Autopsy showed the characteristics of progressive poliodystrophy with degeneration and loss of neurons. Electron microscopy of cerebral cortex showed no mitochondrial abnormalities in neurons or astroglia. Biochemical studies in muscle and/or liver and/or cerebral tissue showed different deficiencies in pyruvate metabolism: in the pyruvate dehydrogenase complex, in the second part of the citric acid cycle (after the oxoglutarate dehydrogenase complex), in the NADH oxidation, in cytochrome aa3 and in pyruvate carboxylase.

A Dutch sibship is described consisting of a girl and a boy affected by the same disease. Both suffered from hydrocephalus and severe generalized weakness with death at 2 days and 4 months respectively. Full autopsy was done on the boy and this revealed a lissencephalic, partly polymicrogyric, neocortex, a bridge of grey matter linking the cerebral hemispheres before and over the lateral ventricles, neocortical dysplasia with subcortical neuronal heterotopic masses, generalized white matter gliosis, also involving the long fibre tracts and generalized vascular proliferation. The cerebellum showed generalized polymicrogyria. Also true hydrocephalus was found presumably related to a malformed aqueduct. Muscle biopsy revealed severe changes, consistent with congenital muscular dystrophy. Representative sections from the girls autopsy revealed an identical pattern of abnormalities. The described pattern fits descriptions of Fukuyama's cerebromuscular dystrophy.

Two maternal cousins are described with the connatal form of Pelizaeus-Merzbacher Disease (PMD) and congenital stridor. Study of brain biopsy material confirms the diagnosis of PMD. The neuropathological findings are suggestive for the transitional form of this disease. Quantitative morphology gives support to the hypothesis that PMD is a disturbance in maturation of neurons and in myelin formation rather than an active degenerative process. The hereditary transmission is most consistent with a sex-linked recessive pattern. Different X-linked signs seem combined in the presented cases.

The patient described in this report was an 11-year-old girl with a negligible heart murmur. The length was below 10th percentile. There appeared to be a cardiomyopathy with, at that moment, no signs of obstruction. There were no evident clinical symptoms of myopathy of skeletal muscle. However, electromyography was myopathic. Biochemical studies revealed no abnormalities. In muscle biopsy sections, the Sudan staining reactions revealed the presence of large amounts of sudanophilic droplets, predominantly in type I fibers. Electronmicroscopy demonstrated lipid excess and accumulations of enlarged, mostly rounded mitochondria in a subsarcolemmal location, with closely packed cristae. In many mitochondria a dense osmiophilic material was present in the spaces between the cristal membranes. The patient's parents were first cousins. One of her brothers who died at the age of 4 1/2 years presumably suffered from the same disease. The pattern of inheritance is most probably autosomal recessive.

A patient had the clinical and neuropathologic signs of Lafora's disease. Skin biopsy specimens from the midcalf area confirmed earlier findings by showing numerous periodic acid-Schiff-positive inclusion bodies in eccrine sweat gland duct cells. In our patient, however, inclusion bodies were more abundantly present in the apocrine sweat gland duct cells of the axilla skin. In brain biopsy specimens and autopsy material the same periodic acid-Schiff-positive inclusion bodies were found. From these data it can be stated that skin biopsy of the axilla is the method of first choice in confirming the diagnosis.

The patient described is a 14-year-old girl who suffered from an oculocutaneous albinism. The developmental milestones were reached with some delay. Gradually she experienced fatiques, and wasting of the pelvic girdle muscles and weakness appeared. In suralis nerve biopsy sections no abnormalities were found. In muscle biopsy sections the characteristic findings of a primary central neuronal muscular atrophy were seen. Based on clinical and histopathological findings it may be stated that the patient is suffering from a motor neuron disease. The chance of the combined occurrence of oculocutaneous albinism and motor neuron disease can be estimated to be one out of 750 X 10(6), unless an incestuous relation is supposed.

This report describes a 3 year-old girl with signs of ventricular hypertrophy, short stature, and persistent diarrhoea (without steatorrhoea or creatorrhoea) which was resistant to therapy. There was no clinical evidence of myopathy but a myopathic pattern was found on electromyography. Biochemical studies revealed no abnormalities. Routine histological studies of biopsied muscle showed no obvious structural abnormalities. Examination of 1 micrometer tissue sections revealed groups of atrophic fibers. Electronmicroscopy revealed widened spaces between the myofibrils with disruption of filament arrangement. The mitochondria in the motor end-plates were very distended and almost devoid of cristae.

Morphological and biochemical studies were performed on a brain biopsy from a patient with typical Lafora disease. Qualitative morphological investigation of the cortex showed that the Lafora bodies were most abundant in layers III and V of the cerebral cortex. They were exclusively located in the neurons and their processes. Quantitative morphological investigation of the cerebral cortex revealed abnormalities of the pyramidal cells of layers III and V. The neurons were often slightly atrophic. There was a reduction in the number of dendrites, in maximal dendritic length, and in the number of spines on the apical dendrites and on the side branches. Because of the biochemical study of the pyruvate metabolism of the gray and white matter of the cortex did not show abnormalities, a mitochondrial dysfunction is not likely.

A boy with recurrent exertional rhabdomyolysis and stunted growth is described. Fetal movements were few and the boy was small for gestational age. He always experienced easy fatigability, and he noted bouts of pigmenturia associated with episodes of considerable malaise. The change in color of the urine was caused by myoglobin. An electromyogram was myopathic. CPK rose during 60 minutes mild exercise. Prolonged moderate exercise could not be performed. Histopathological examination of muscle biopsy revealed an increase in the number of 11C fibres (20%). Electronmicroscopy revealed the wavy outline of a number of fibres and hypertrophy of sarcoplasmic reticulum elements. No cause for the stunted growth could be detected.