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Biomedical subjects

G Lyon

Publications and source records attributed to G Lyon.

At least 37 records · Page 2Linked to original sources
PubMed1985

On the positive semiology of acquired aphasia in children.

Eleven unselected cases of aphasia in children seen over a three-year period in a neuropaediatric centre are reported. Contrary to current reports in the literature, the children disclosed a semiology similar to that of adults, particularly for frequency and distribution of 'positive signs' such as paraphasias. The reasons for this discrepancy are discussed and an hypothesis of early intrahemispheric specialization is proposed.

Adolescent↗
PubMed1984

Prenatal cytomegalovirus disease and cerebral microgyria: evidence for perfusion failure, not disturbance of histogenesis, as the major cause of fetal cytomegalovirus encephalopathy.

From the study of four personal cases of microgyria related to fetal CMV infection and a review of the literature it is concluded that: 1) Microgyria is a frequent neuropathological finding in this disease - 2) CMV microgyria is the result of an insufficiency of cerebral blood supply and is not due to a disturbance of neurogenesis or histogenesis as a consequence of a direct cytopathic effect of the virus on germinal cells. The way by which the CMV causes cerebral ischemia - angeitis or more probably, transient systemic perfusion failure, - is discussed, but remains obscure. Other viruses may act on the fetal brain by way of circulatory disturbances.

Brain↗
PubMed1983

Vision attention and discrimination in infants at risk and neurological outcome.

Visual behavior has been studied in 129 high risk infants in order to appreciate the value of eye opening, visual fixation and pursuit and visual discrimination in predicting permanent brain damage. The assessment of visual discrimination according to Fantz and Miranda, has proven to be particularly helpful after corrected term. These tests allow the detection of severe permanent neurological sequelae even when visual attention and neurological examination appear to be normal. Certainly, during the 3 first months of life, visual behavior is of more value to predict future neurological outcome than the classical neurological examination.

Asphyxia Neonatorum↗
PubMed1983

[Joubert syndrome. Clinical and anatomo-pathologic study. Etiopathogenetic hypotheses].

Joubert's syndrome is characterized by an agenesis of the vermis and an unique respiratory abnormality consisting of bouts of extreme tachypnea and prolonged apneas. Three patients with this syndrome are reported with a polygraphic study and a recording of intracranial pressure in one of them and a pathological study in another. It is suggested that the agenesis of the vermis is caused by a prenatal hydrocephalus as is probably the case in the Dandy-Walker syndrome. A comparison is established between these two syndromes. The periods of tachypnea-apnea could represent the persistence of a fetal pattern of respiration with an excessive response to various stimuli, and might be explained by the delayed maturation of inhibitory mechanisms necessary for the establishment of the normal pattern of respiration and sleep. The possible role of a total vermian agenesis in the pathogenesis of respiratory abnormality is discussed.

Cerebellum↗
PubMed1982

Ependymitis, leukoencephalitis, hydrocephalus, and thrombotic vasculitis following chronic infection by mouse hepatitis virus 3 (MHV 3).

Mouse hepatitis virus 3 (MHV 3) is either avirulent (resistant mice), hepatotropic (susceptible mice), or neurotropic (semisusceptible mice), depending on the strain of mice infected. In semisusceptible mice, infection led first to a transient meningitis, ependymitis, and leukoencephalitis, followed by a permanent communicating hydrocephalus and, later on, to a chronic thrombotic vasculitis affecting meningeal and parenchymal vessels at the brain stem level. Small foci of ischemic necrosis related to vascular occlusions were seen in the dorsal brain stem. Cyclophosphamide treatment of semisusceptible mice significantly reduced the meningeal infiltrates but did not prevent the development of hydrocephalus and other neuropathologic changes. Identical lesions occurred in fully susceptible mice infected with a low dose of virus, but no neurologic disorder could be induced in genetically resistant mice even following immunosuppression or intracranial inoculation. The leukoencephalitis differed from the demyelinating lesions observed with MHV 4. Vascular lesions were of particular interest. More attention should be given to the possibility of virus induced chronic cerebral vasculitis in man.

Animals↗
PubMed1982

Congenital hypomyelination polyneuropathy. Pathological findings compared with polyneuropathies starting later in life.

Biopsies from patients with congenital hypomyelination polyneuropathy (Group I) and with late infantile (Group II) and juvenile (Group III) forms of hereditary motor and sensory neuropathy (HMSN) type III were compared, using morphometric methods and ultrastructural analysis. In congenital polyneuropathies (Group I), myelin sheaths were practically absent and onion bulbs, essentially made of multiple laminae of double layered basement membrane, surrounded every axon in the size range of normal myelinated axons. The number of these axons was markedly reduced. Serial sectioning of an isolated fibre showed that the territory of successive clusters of Schwann cell nuclei was considerably reduced when compared with the biopsies in Groups II and III and with normal controls. Fibres without myelin surrounded by multiple layers of basement membrane represented between 25 and 50 per cent of the entire population of fibres in the size range of myelinated fibres in Group II and were practically absent in Group III. The number of "myelinated' fibres (that is, fibres with myelin, and amyelinate or demyelinated fibres) was normal in Groups II and III. Although there is no indication that congenital hypomyelination onion bulb polyneuropathy is a separate entity, it can be considered as a subtype of Dejerine-Sottas disease (HMSN type III). In this disease there is a gradient of severity both in clinical expression and in the disorder of Schwann cells. In the severe congenital form, all Schwann cells are affected and are incapable of forming myelin. The diminution of the number of nerve fibres in the "myelinated' fibre size range, whether or not related to a prenatal involvement of Schwann cells, is another expression of the gravity of this form. The proportion of amyelinate fibres, i.e. with Schwann cells incapable of forming myelin, becomes less in the more benign late infantile and juvenile forms of the disease in which a process of demyelination and remyelination takes place. The literature on the congenital neuropathies, a heterogeneous assembly of diseases, is reviewed.

Adolescent↗
PubMed1982

Liver peroxisome damage during acute hepatic failure in partial ornithine transcarbamylase deficiency.

A boy with ornithine transcarbamylase (OTC) deficiency was relatively symptom free for 9 months and then developed an acute episode with liver failure and metabolic imbalance. Subsequently there was severe cerebral atrophy. Liver ornithine transcarbamylase activity was 3% of the normal mean. Of considerable interest was the finding of an accelerated breakdown of liver peroxisomes during the acute phase.

Acute Disease↗
PubMed1981

A Golgi study of the brain malformation in Zellweger's cerebro-hepato-renal disease.

Characteristic neuronal heterotopias in two cases of Zellweger's cerebro-hepato-renal disease were studied with the Golgi method. In the corona radiata, heterotopias consist of large fields of small or medium-sized radial pyramids, and of dense clusters containing larger, randomly oriented pyramidal cells and multipolar neurons, some of which resemble granule cells. The latter type of heterotopia could result from a focal destructive process at a relatively early stage of neuronal migration. In the cerebellar white matter, heterotopic masses contain Purkinje cells and possibly Golgi neurons but no granule or basket cells. The mispositioned Purkinje cells resemble the subcortical and intragranular Purkinje cells of the reeler mutant mouse and those of the weaver mutant. The morphology of neurons in the abnormally convoluted olivary nucleus is normal.

Bile Ducts, Intrahepatic↗
PubMed1981

Formation of "neo-cortex" in a congenital human teratoma.

A congenital human teratoma contained a neuroectodermal mass with architectonic features similar to those of the normal developing neo-cortex. Surrounding a central cavity, a germinal, an intermediate and a cortical zone were clearly distinguishable from innermost to outermost. Glial fibers coursed radially through the intermediate and cortical zones. In the "cortical plate" neuronal elements were oriented radially with an inside out gradient of differentiation. Mesothelial tissue covered the outer surfaces of the "cortex". Over limited sectors a gap in the integrity of the meso-glial barrier were associated with neuroglial ectopias. The following points are of neurobiologic importance: the information of the "miniature cerebral cortex" occurred in the absence of any influence of afferent subcortical fibers. The radial alignment of glial fibers between the germinal pseudostratified epithelium and the outer surface occurred only in sectors of the neuroectodermal mass where a "neo-cortex" was present, and may therefore have been a critical determinant in the formation of the "cortical plate". The integrity of the outer glial mesenchymal barrier may be necessary for the normal arrangement of cortical neurons.

Brain Neoplasms↗
PubMed1981

Pooled European series of hereditary peripheral neuropathies in infancy and childhood. A "correspondence work shop" report of the European Federation of Child Neurology Societies (EFCNS).

A European series of 287 cases of "pure" peripheral neuropathy, pooled from 14 neuropediatric centres, has been analysed retrospectively with particular emphasis on the hereditary motor and sensory neuropathies (HMSN) which comprised 241 of the patients. Due to incomplete information in many records it has only been possible to make a crude analysis of the problems of diagnosis and classification. More than half of the HMSN series conform to the diagnosis of HMSN I (charcot-Marie-Tooth-Roussy-Levy disease), A relatively homogeneous group but with large variations in age of onset and severity of disease between individuals in the same family. In five of the 147 cases the onset was at or before birth. An overdiagnosis of HMSN III (Déjérine-Sottas' disease) was considered probable due partly to an unawareness of the high frequency of subclinical carriers among parents in families with HMSN I. Cases with axonal types of polyneuropathy, appearing sporadically or with suspected autosomal dominant (HMSN II) or recessive inheritance, occurred with unexpected frequency in children. This group of 60 pooled European cases was considered worthy of a particularly thorough follow-up and further investigation in order to achieve a better delineation between different subtypes. Cases with an onset before birth or very early in infancy (20 cases) comprised a heterogeneous group with some special subtypes. Surprisingly enough, no less than 5 of the 20 cases represented HMSN I. Cerebrospinal fluid protein levels were not found to be useful for differentiating various types of HMSN. Elevated levels were revealed in about half of the examined cases of HMSN I and in 75% of cases of HMSN III, the levels of increase showing a marked overlap. In nearly all of the axonal cases investigated the CSF protein was normal.

Axons↗
PubMed1981

Progressive expanding congenital porencephalies: a treatable cause of progressive encephalopathy.

In congenital porencephalies, diverticulation of the lateral ventricle is a dynamic process producing compression and stretching of the brain tissue bordering the diverticulum, bulging of the overlying skull, macrocephaly, and occasionally progessive neurologic signs (hemiplegia, raised intracranial pressure), even when the rest of the ventricular system is not dilated and the CSF pressure is normal. Ventriculoperitoneal shunting can result in remarkable improvement of focal motor deficits and may apparently also play a beneficial role on further mental development. Successive computed tomography scans demonstrate that the brain parenchyma, which had been stretched by the porencephalic pouch, is capable of regaining near normal thickness. Congenital porencephalies are initiated by a limited destructive brain lesion, but the gradual expansion of the ventricular herniation may imply a mechanism identical to that which has been postulated in normal pressure hydrocephalus. Nine cases of unilateral "expanding" congenital porencephalies are presented and the treatment of this condition is discussed.

Brain↗
PubMed1981

[Intracranial arteriovenous malformations in childhood. A revision of 25 cases (author's transl)].

Clinical features of A-V intracranial malformations during infancy, childhood and adolescence are reviewed on this series of 25 less-than-15-years-old patients. Great cirsoid malformations (2 cases) and aneurysms of the vein of Galen (2 cases) may cause diffuse brain-steal-ischaemia, hydrocephalus and congestive heart failure in early ages, event at birth. The clinical manifestations of brain angiomas rather begin from the fifth year of life. Little sized angiomas cause preferentially intracranial haemorrhagic attacks (17 of 21 cases in this series). Middle sized racemic angiomas cause focal seizures and/or focal neurologic signs. In 5 patients an intracranial bruit of a great diagnostic value was present. Combining brain radioisotopic studies, brain C.A.T. and angiography near 100% of intracranial A-V malformations can be diagnosed early after clinical suspicion.

Adolescent↗
PubMed1980

Chronic progressive encephalitis in children with x-linked hypogammaglobulinemia.

This report is on six cases of a chronic relentlessly progressive encephalitis occurring in boys with congenital hypogammaglobulinemia presumably of the x-linked type, which are thought to represent a separate neurological entity. Intellectual deterioration, dysarthria, spasticity, ataxia, optic atrophy and an increase of lymphocytes in the cerebrospinal fluid, were the main clinical signs. The pathological picture was that of a viral encephalitis, but all virological investigations on brain biopsies and CSF were negative. The significance of intra-cisternal tubuloreticular inclusions in brain endothelial cells, similarities with chronic rubella encephalitis, and the role of the immunological deficiency are discussed. Sofar, the cause of this new type of encephalitis remains obscure.

Adolescent↗