Spongy glio-neuronal dystrophy in infancy and childhood

Astrocytic pathology in Alpers' syndrome

Refractory epilepsy is the main neurological manifestation of Alpers' syndrome, a severe childhood-onset mitochondrial disease caused by bi-allelic pathogenic variants in the mitochondrial DNA (mtDNA) polymerase gamma gene (POLG). The pathophysiological mechanisms underpinning neuronal hyperexcitabilty leading to seizures in Alpers' syndrome remain unknown. However, pathological changes to reactive astrocytes are hypothesised to exacerbate neural dysfunction and seizure-associated cortical activity in POLG-related disease. Therefore, we sought to phenotypically characterise astrocytic pathology in Alpers' syndrome. We performed a detailed quantitative investigation of reactive astrocytes in post-mortem neocortical tissues from thirteen patients with Alpers' syndrome, eight neurologically normal controls and five sudden unexpected death in epilepsy (SUDEP) patients, to control for generalised epilepsy-associated astrocytic pathology. Immunohistochemistry to identify glial fibrillary acidic protein (GFAP)-reactive astrocytes revealed striking reactive astrogliosis localised to the primary visual cortex of Alpers' syndrome tissues, characterised by abnormal-appearing hypertrophic astrocytes. Phenotypic characterisation of individual GFAP-reactive astrocytes demonstrated decreased abundance of mitochondrial oxidative phosphorylation (OXPHOS) proteins and altered expression of key astrocytic proteins including Kir4.1 (subunit of the inwardly rectifying K⁺ ion channel), AQP4 (astrocytic water channel) and glutamine synthetase (enzyme that metabolises glutamate). These phenotypic astrocytic changes were typically different from the pathology observed in SUDEP tissues, suggesting alternative mechanisms of astrocytic dysfunction between these epilepsies. Crucially, our findings provide further evidence of occipital lobe involvement in Alpers' syndrome and support the involvement of reactive astrocytes in the pathogenesis of POLG-related disease.

Delineating selective vulnerability of inhibitory interneurons in Alpers’ syndrome

Aims

Methods

Results

Conclusions

Analyzing high-dimensional cytometry data using FlowSOM

The dimensionality of cytometry data has strongly increased in the last decade, and in many situations the traditional manual downstream analysis becomes insufficient. The field is therefore slowly moving toward more automated approaches, and in this paper we describe the protocol for analyzing high-dimensional cytometry data using FlowSOM, a clustering and visualization algorithm based on a self-organizing map. FlowSOM is used to distinguish cell populations from cytometry data in an unsupervised way and can help to gain deeper insights in fields such as immunology and oncology. Since the original FlowSOM publication (2015), we have validated the tool on a wide variety of datasets, and to write this protocol, we made use of this experience to improve the user-friendliness of the package (e.g., comprehensive functions replacing commonly required scripts). Where the original paper focused mainly on the algorithm description, this protocol offers user guidelines on how to implement the procedure, detailed parameter descriptions and troubleshooting recommendations. The protocol provides clearly annotated R code, and is therefore relevant for all scientists interested in computational high-dimensional analyses without requiring a strong bioinformatics background. We demonstrate the complete workflow, starting from data preparation (such as compensation, transformation and quality control), including detailed discussion of the different FlowSOM parameters and visualization options, and concluding with how the results can be further used to answer biological questions, such as statistical comparison between groups of interest. An average FlowSOM analysis takes 1-3 h to complete, though quality issues can increase this time considerably.

Dissecting the neuronal vulnerability underpinning Alpers' syndrome: a clinical and neuropathological study

Alpers’ syndrome is an early‐onset neurodegenerative disorder often caused by biallelic pathogenic variants in the gene encoding the catalytic subunit of polymerase‐gamma (POLG) which is essential for mitochondrial DNA (mtDNA) replication. Alpers’ syndrome is characterized by intractable epilepsy, developmental regression and liver failure which typically affects children aged 6 months–3 years. Although later onset variants are now recognized, they differ in that they are primarily an epileptic encephalopathy with ataxia. The disorder is progressive, without cure and inevitably leads to death from drug‐resistant status epilepticus, often with concomitant liver failure. Since our understanding of the mechanisms contributing the neurological features in Alpers’ syndrome is rudimentary, we performed a detailed and quantitative neuropathological study on 13 patients with clinically and histologically‐defined Alpers’ syndrome with ages ranging from 2 months to 18 years. Quantitative immunofluorescence showed severe respiratory chain deficiencies involving mitochondrial respiratory chain subunits of complex I and, to a lesser extent, complex IV in inhibitory interneurons and pyramidal neurons in the occipital cortex and in Purkinje cells of the cerebellum. Diminished densities of these neuronal populations were also observed. This study represents the largest cohort of post‐mortem brains from patients with clinically defined Alpers’ syndrome where we provide quantitative evidence of extensive complex I defects affecting interneurons and Purkinje cells for the first time. We believe interneuron and Purkinje cell pathology underpins the clinical development of seizures and ataxia seen in Alpers’ syndrome. This study also further highlights the extensive involvement of GABAergic neurons in mitochondrial disease.

Loss of mtDNA activates astrocytes and leads to spongiotic encephalopathy

Mitochondrial dysfunction manifests as different neurological diseases, but the mechanisms underlying the clinical variability remain poorly understood. To clarify whether different brain cells have differential sensitivity to mitochondrial dysfunction, we induced mitochondrial DNA (mtDNA) depletion in either neurons or astrocytes of mice, by inactivating Twinkle (TwKO), the replicative mtDNA helicase. Here we show that astrocytes, the most abundant cerebral cell type, are chronically activated upon mtDNA loss, leading to early-onset spongiotic degeneration of brain parenchyma, microgliosis and secondary neurodegeneration. Neuronal mtDNA loss does not, however, cause symptoms until 8 months of age. Findings in astrocyte-TwKO mimic neuropathology of Alpers syndrome, infantile-onset mitochondrial spongiotic encephalopathy caused by mtDNA maintenance defects. Our evidence indicates that (1) astrocytes are dependent on mtDNA integrity; (2) mitochondrial metabolism contributes to their activation; (3) chronic astrocyte activation has devastating consequences, underlying spongiotic encephalopathy; and that (4) astrocytes are a potential target for interventions.

Astrocytes in the brain are metabolically dynamic. Here, Ignatenko, Chilov and colleagues delete mitochondrial DNA (mtDNA) in a cell type specific manner, and show that inactivation of mtDNA helicase Twinkle in astrocytes leads to spongiotic encephalopathy.

A case of spongiform polioencephalomyelopathy in a cat with a history of behavioural problems

A 7-month-old, entire female, domestic shorthair cat was referred to our behavioural service owing to soiling in the house and a play-related problem. The owners’ complaints were that the cat had never used the litter tray, and it did not know how to play. After reviewing the behavioural history, a problem of substrate preferences acquisition was suspected with regard to the elimination problem. During the consultation, the physical examination was unremarkable, but the neurological examination revealed a moderate and hypermetric ataxic gait, and a bilateral lack of menace response. Some degree of visual impairment was suspected. The problem was located in the central nervous system (CNS); specifically, an intracranial and multifocal problem was diagnosed. After a complete work-up (complete ophthalmological examination, complete blood count and a complete biochemistry panel, feline immunodeficiency virus/feline leukaemia virus test, thorax radiographs, abdominal ultrasound, brain magnetic resonance imaging [0.2 T], cerebrospinal fluid analysis and a urinary metabolic screen test), a degenerative CNS problem was suspected. No treatment was prescribed for the neurological problem. Regarding the problem of soiling in the house, reward-based training with a clicker was used, and the cat partially improved in a few weeks. Three months later, the cat was referred to the neurology service in status epilepticus. A symptomatic treatment was prescribed, with a mild response. After 2 years of treatment and a progressive worsening, the cat was euthanased. Necropsy revealed spongiform polioencephalomyelopathy. In order to rule out prion aetiology a PrPsc inmunohistochemistry assay was performed, and the results were negative. Congenital spongiform polioencephalomyelopathy (CSP) was diagnosed. We strongly suggest that the cat’s behavioural clinical signs were caused by the CSP, causing learning impairment. To the best of our knowledge, this would be the first case in which a congenital degenerative disease affected a cat’s capability to learn, leading to behavioural signs as the main complaint of the owners, even before neurological signs are detected by the owners.

Phenotypic and genotypic variability in Alpers syndrome

BACKGROUND

Alpers syndrome is one of the most common phenotypes of mitochondrial disorders in early childhood and has been associated with pathogenic mutations in POLG1.

AIMS

To investigate the phenotypic-genotypic correlations in Alpers syndrome and to identify potential differences among patients with Alpers syndrome with or without pathogenic POLG1 mutations.

METHODS

Patients with the phenotype of Alpers syndrome who were referred to our pediatric hospital during 1984-2007 and were diagnosed with mitochondrial encephalomyopathy underwent further biochemical, morphological and genetic investigations.

RESULTS

A total of 19 patients were included in the study, of whom six had pathogenic POLG1 mutations including a novel mutation (c.907 G>A, p.Gly303Arg). Complete mtDNA sequencing in the subgroup without POLG1 mutations showed 5 novel and 5 very rare mtDNA variants considered as rare polymorphisms. Compared to POLG1(-) patients, the POLG1(+) patients more frequently had seizures at onset, which often became refractory. Ataxia and stroke-like episodes were much more common, while microcephaly and spasticity were encountered almost solely in the POLG1(-) group. Hepatic and ophthalmological involvement developed in 79% and 88% of patients, respectively. Most of the patients in both groups had predominant deficiency of complex I. In addition to the major degenerative changes in the cerebral cortex, the basal ganglia, thalamus and white matter were also involved to variable extent.

CONCLUSION

Alpers syndrome is a heterogeneous syndrome that should be considered in patients with early-onset progressive cortical encephalopathy regardless of liver involvement. The phenotype is different depending on the presence or absence of POLG1 mutations.

Progressive neuronal degeneration of childhood: prenatal diagnosis by MRI

We report two cases in the same family of progressive neuronal degeneration of childhood--Alpers syndrome--with prenatal MRI findings in one case. The first infant presented at birth with severe microcephaly, then rapidly evolved to progressive encephalopathy with refractory epilepsy, leading to death at 10 months. Biochemical investigations including liver function tests were normal. CT and MRI showed severe diffuse brain atrophy. The diagnosis of progressive neuronal degeneration of childhood was made on the clinical and imaging data. The second pregnancy was marked by gradual decrease of fetal cerebral biometry and a prenatal MRI performed at 32 weeks showed diffuse cortical atrophy, as observed in the sibling. The infant died at 5 months. Neuropathological findings were consistent with Alpers syndrome.

Clinical study of catastrophic infantile epilepsy with focal seizures

This study investigated clinico-electrical and etiologic characteristics of catastrophic infantile epilepsy with focal seizures developed in early infancy. The patients included 15 children who fulfilled the following criteria: seizure onset before 12 months of age, presence of daily focal or secondarily generalized seizures resistant to antiepileptic drugs for at least 3 months, and exclusion of Ohtahara and West syndromes. Patients were classified into three subgroups. Three patients demonstrated progressively deteriorating neurologic symptoms associated with progressive cerebral atrophy and multifocal seizure onset. Three other children were characterized by hemiparesis and exclusively lateralized seizure onset because of focal cortical dysplasia in the contralateral hemisphere. The remaining nine children did not demonstrate any rapidly progressive neurologic deterioration or increasing cerebral atrophy and exhibited multifocal seizure onset. At the last examinations, all except one patient demonstrated moderate to severe psychomotor retardation. Catastrophic infantile epilepsy with focal seizures tended to demonstrate multifocal seizure onset and a deleterious clinical course with numerous focal seizures regardless of etiology. Because migratory focal seizures appear to be common in these infants, we have to search for the underlying etiopathogenesis of these patients, including not only metabolic errors but also localized or lateralized structural abnormality.

Alpers progressive infantile neuronal poliodystrophy: an acute neonatal form with findings of the fetal akinesia syndrome

We report on 8 patients from two families with Alpers syndrome. The onset in one family was prenatal and in the 4 patients who were examined, severe microcephaly, intrauterine growth retardation, and typical manifestations of fetal akinesia, including retrognathia, joint limitations, and chest deformity were found. The second family presented with an early infantile form. All the affected offspring had micrognathia and one had findings of fetal akinesia, comparable to those seen in the other family. Microcephaly was mild at birth and progressed with age. Refractory neonatal convulsions, swallowing difficulties, and pneumonia complicated the clinical course of patients in both families, and all the patients died before age 20 months. Results of comprehensive biochemical and metabolic studies in both families were normal and the diagnosis was supported by demonstration of extensive progressive brain atrophy on CT and typical histological findings. Patients without a detectable defect in energy metabolism and normal liver histology comprise a distinct subset of Alpers syndrome. Until the metabolic defect(s) is defined, we suggest naming the acute neonatal form of this subset of Alpers syndrome "type 1."

Progressive neuronal degeneration of childhood (Alpers syndrome) with hepatic cirrhosis

Four children, from two families, suffered from fatal degeneration of the cerebral grey matter. Their disease was characterised by intractable epilepsy, epilepsia partialis continua, progressive deterioration, and terminal hepatic dysfunction. EEG showed marked and distinctive slow wave abnormality, visual evoked responses were diminished, and cerebral atrophy was seen on CT scan. Pathological findings were of neuronal loss and hepatic cirrhosis. The combination of cerebral degeneration, hepatic disease and familial occurrence suggests an inborn error of metabolism with autosomal recessive inheritance. The features described are those of Alpers syndrome, especially the recently delineated subgroup with progressive neuronal degeneration and liver disease.

Early childhood hepatocerebral degeneration misdiagnosed as valproate hepatotoxicity

Four unrelated children were thought to have valproate-associated hepatotoxicity. They presented with recurrent partial secondarily generalized status epilepticus and epilepsia partialis continua followed by mental and motor regression. Despite treatment with multiple antiepileptic medications, they continued to have seizures. After initiation of valproic acid (VPA), all 4 manifested liver failure within 3 months. Two of these children each had 1 sibling who was not exposed to VPA, but who developed the same clinical picture including liver failure. At the time of autopsy, all 6 children had similar neuropathological findings with focal areas of spongiosis and neuronal loss, diffuse gliosis, and Alzheimer type II cells. One VPA-treated patient underwent a successful liver transplantation only to die from relentlessly progressive neurological deterioration. We propose that many of the reported patients with VPA-associated hepatotoxicity represent undiagnosed patients with early childhood hepatocerebral degeneration, the Huttenlocher variant of Alpers' syndrome. This disease manifests by obstinate partial seizures, recurrent partial secondarily generalized status epilepticus, epilepsia partialis continua, psychomotor deterioration, and hepatic dysfunction that is exacerbated by VPA administration. The accelerated demise from liver failure in the nontransplanted patients before the central nervous system pathology fully evolves makes the diagnosis of this rare condition difficult. The occurrence of disease in the unexposed siblings suggests recessive inheritance.

Liver involvement in Alpers disease

Alpers disease consists of diffuse cerebral degeneration manifested as developmental delay, seizures, vomiting, and progressive neuromuscular deterioration, with liver disease and death. We report the clinical course of the liver disease, histologic progression of the hepatic lesions, and etiologic investigations in five patients (four girls, three kinships). All had grown and developed normally until seen at 6 to 36 months of age (mean 20 months), with vomiting (n = 5), progressive hypotonia (n = 3), or seizures (n = 2). All had been given anticonvulsants, including valproic acid in three. Liver disease was noted at a mean age of 35 months (range 9 to 67 months), with hepatomegaly (two patients), abnormal hepatic synthetic function (three) or transaminase values (three), and cirrhosis in one. Patients survived for a mean of 4.6 weeks (range 1 to 8 weeks) after the identification of liver disease; all died of hepatic failure. Results of evaluation for infectious and metabolic causes of liver disease and causes of degenerative neuromuscular disease were negative in all patients. Premortem liver biopsy specimens (n = 3) demonstrated an early lesion consisting of lobular disarray, microvesicular steatosis, periportal acute and chronic inflammation, and individual hepatocyte necrosis. Autopsy findings (n = 5) consisted of macrovesicular steatosis, massive hepatocyte dropout, and proliferation of bile ductular elements, with almost complete replacement of hepatocytes by proliferating bile ductular elements in two patients. Brain showed characteristic neuronal degeneration. We conclude that Alpers disease can be a cause of rapidly progressive liver failure in early childhood. Although the cause of this autosomal recessive disease is not known, it does not appear to be related to peroxisomal dysfunction.

EEG findings in children and adolescents with mitochondrial encephalomyopathies: a study of 25 cases

EEG was studied in 25 children and adolescents with mitochondrial encephalomyopathies, defined on the basis of clinical, biochemical and morphological criteria. Twenty cases conformed to well-known mitochondrial syndromes: Alpers syndrome [6], Leigh syndrome [2], MERRF (myoclonus epilepsy and ragged red fibers) syndrome [3], MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) syndrome [5] and Kearns-Sayre syndrome [4]. Many patients were followed for several years with repeated EEG. In all, 112 EEG records were included in the study. A common feature of all the mitochondrial encephalomyopathic syndromes was slowing of the alpha rhythm. Epileptic discharges were seen in most syndromes. In spite of the small number of cases in each group, in Alpers, MERRF and MELAS syndromes we found sequential EEG patterns which seemed to be typical of the respective syndromes. In contrast, in Kearns-Sayre syndrome, a slow background rhythm was the only consistent finding. We conclude that EEG, especially repeated recordings, may be of help in the diagnostic evaluation of mitochondrial encephalomyopathies.

Progressive encephalopathy with edema, hypsarrhythmia, and optic atrophy (PEHO syndrome)

We describe 14 patients, from 11 families, who have a progressive encephalopathy with early onset. The clinical signs of the disease are severe hypotonia, convulsions with hypsarrhythmia, profound mental retardation, hyperreflexia, transient or persistent edema, and optic atrophy. These findings and the characteristic dysmorphic features allow recognition of these patients, although no basic metabolic defect has been found. Microcephaly and atrophy of the brain develop, especially in the cerebellar and brain stem areas. An autosomal recessive mode of inheritance is likely.

Progressive neuronal degeneration of childhood with liver disease (Alpers-Huttenlocher syndrome): a personal review

Thirty-two autopsied cases of progressive neuronal degeneration of childhood with liver disease are reviewed. The typical clinical course is intractable seizures and liver failure following a period of developmental delay and failure to thrive in early infancy, but some children first present with seizures. Characteristic changes on the electroencephalogram, loss of visual-evoked potentials, occipital atrophy on computed tomographic scan, and particular changes on liver biopsy may assist diagnosis. Most patients succumb in less than 3 years, but some have a protracted survival into their teens, and very rarely they may present in early adulthood. Liver pathology comprises fatty change, hepatocyte loss, bile duct proliferation, fibrosis, and often cirrhosis. Gradual progression can be followed in sequential biopsies. Macroscopically, the cerebral cortex is variably involved, but usually there is patchy thinning and discoloration, with a striking predilection for the striate cortex. Microscopic changes include spongiosis, neuronal loss, and astrocytosis, which progresses down through the cortical layers. All areas may be affected but the calcarine cortex is usually most affected. Etiology is still obscure, though mitochondrial and slow viral disorders have been postulated.

Intracerebral distribution of mitochondrial abnormalities in 21 cases of infantile spongy dystrophy

Using a monoclonal antibody to an inner mitochondrial membrane antigen and light microscopic immunohistochemistry, we investigated the distribution of increased immunostaining (mitochondrial anomalies, MA) on paraffin sections from 21 brains with infantile spongy dystrophy (Leigh's disease, 8; Canavan's disease, 4; Alpers' syndrome, 2; mixed spongy dystrophy, 7). Compared with an age-matched control group, MA were present in all cases of Leigh's disease (leptomeningeal and intracerebral endothelial and vascular smooth muscle cells, choroid plexus epithelia, ependymal cells, astrocytes or some neurons), in 2 cases of Canavan's disease and the Alpers' syndrome cases (astrocytes and occasionally some neurons). The MA were restricted to spongy areas in Canavan's disease and Alpers' syndrome, whereas they were distributed throughout the brain in Leigh's disease. In mixed spongy dystrophies the Leigh histology was associated with MA, but not the Canavan histology. Brains with Wernicke's encephalopathy (3 cases), adult infarction (3), and multicystic encephalopathy (5) showed no MA, but one with methylmalonaciduria did. Our results substantiate the classification of Leigh's disease as primary mitochondrial encephalopathy.

Progressive neuronal degeneration of childhood (PNDC) with liver disease

Thirteen children with progressive neuronal degeneration and liver disease are reported. Clinical features included developmental delay after a normal initial period with later onset of intractable epilepsy. The EEG showed an unusual but characteristic pattern, and visual evoked responses (VER) were abnormal. Rapidly progressive cerebral atrophy was seen on computerized axial tomography (CAT). Inheritance was consistent with an autosomal recessive trait. Pathological findings were neuronal degeneration and spongy change of the cerebral cortex. The calcarine cortex was more severely affected than other areas. Hepatic lesions included severe fatty change and cirrhosis. In six patients liver disease was detected before the onset of epilepsy and exposure to anticonvulsants. Two others were reported to have died from sodium valproate (SV) toxicity, but both had abnormal liver enzymes before treatment with SV, and in both the neuropathological findings were indicative of PNDC. During life, PNDC may be indicated by the characteristic clinical course, abnormal liver function tests, and abnormalities of EEG, VER, and CAT.

Intrauterine multisystem atrophy in siblings: a new genetic syndrome?

A condition is described in two siblings, dying in early infancy, characterized by an extreme degree of cerebellar hypoplasia, hypoplasia or atrophy of the brain stem with partial preservation of cranial and spinal nerve nuclei, total degeneration of basal ganglia and thalamus, laminar atrophy of the cerebral cortex, and accumulation of sudanophil lipid in astrocytes and macrophages of the hemispheric white matter. It is suggested that this condition, possibly inherited as an autosomal recessive, may represent a progressive multisystem atrophy occurring in utero, affecting various parts of the neuraxis in different stages in their development.

Progressive poliodystrophy (Alpers' disease) with a defect in cytochrome aa3 in muscle: a report of two unrelated patients

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.

Creutzfeldt-Jakob disease in an adolescent

A 16-year-old boy was stricken with a progressive neurologic disorder characterized primarily by dementia progressing to severe neurologic debility in 12 months and death 28 months following the first symptoms. Pathologic examination showed a spongiform encephalopathy, consistent witha clinical diagnosis of Creutzfeldt-Jakob disease (CJD). The noteworthy features of the case are the age of onset, the somewhat prolonged course an the amount of white matter change. These are discussed within the frame of reference of CJD and the spongiform encephalopathies of infancy and childhood. Animal inoculation studies employing post-mortem embalmed brain as inoculum are currently in progress to determine the transmissibility of this patient's disease.

Myoclonus epilepsy associated with ragged-red fibres (mitochondrial abnormalities ): disease entity or a syndrome? Light-and electron-microscopic studies of two cases and review of literature

A report is given of an association of dyssynergia cerebellaris myoclonica associated with Friedreich's ataxia and mitochondrial myopathy in 2 patients. They had suffered from gradually increasing bursts of myoclonus since the wage of 14 and childhood, respectively. The other striking clinical features included generalized convulsions, mental deterioration, intention tremor, ataxia, muscular atrophy and deformity of feet. Muscle biopsies revealed ragged-red fibres in both cases. On electron microscopy these fibres contained subsarcolemnal aggregations of abundant abnormal mitochondria with proliferation of inner membranes or paracrystalline inclusions. One of these patients showed elevated blood lactate and pyruvate with an increased lactate/pyruvate ration, apparently of primary origin. These 2 cases resemble those reported briefly by Tsairis et al. (1974). An association of dyssynergia cerebellaris myoclonica associated with Friedreich's ataxia and mitochondrial myopathy in these 2 patients is unlikely to be coincidental but may represent one nosological entity. This myoclonus epilepsy syndrome associated with ragged-red fibres is compared with other possibly related mitochondrial encephalomyopathies.

Spongy degeneration of grey matter in 3 children. Neuropathological report

Spongy degeneration of the cerebral grey matter is reported in 3 unrelated boys dying at the ages of 15 and 16 months and 3 years. Some of the neuropathological changes in the cases presented here and in other similar cases are like those in Creutzfeldt-Jakob disease and in kuru, conditions which have recently been transmitted to monkeys. The aetiology of spongy degeneration in children is not known, and it would be worth while to find out whether the disease is transmissible.

Spongy glio-neuronal dystrophy: a degenerative disease of the nervous system

A case of spongy glio-neuronal dystrophy is reported. The clinical features included mental and motor retardation in early infancy after a normal birth, and from the age of 4 years increasingly severe attacks of multifocal epilepsy, with prolonged postictal coma, myoclonic twitching and nystagmus, and at times hemiplegia for one to two weeks. Acidosis was present during the periods of postictal coma. Jaundice occurred several days before death at the age of 5 years. Neuropathological examination revealed severe spongy degeneration in the thalamus and dentate nucleus, and the cerebral cortex to a lesser degree, with sparing of the white matter. There was partial necrosis of liver cells and in some areas regenerative nodules. Possible aetiological factors linking the cerebral and hepatic pathology are discussed.

Progressive cerebral poliodystrophy--Alpers' disease. Disorganized giant neuronal mitochondria on electron microscopy

Three siblings who suffered from progressive mental retardation, seizures, and rigidity showed degeneration of the cerebral cortex. This was manifested by severe to complete neuronal loss with astrogliosis and microgliosis. In one child a brain biopsy was performed at the age of 3 months. The only lesion found was large disorganized perinuclear mitochondria in the neurones. The possibility that the cerebral poliodystrophy is due to an inherited mitochondrial disorder is discussed.