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Volume 68 September1975

561

Section of Pathology President J W Stewart MB Meeting 11 February 1975

The Pathology of Neurological Deficit Etiology of Mental Retardation Professor J P M Tizard (John Radcliffe Hospital, Oxford) pointed out the size of the problem, e.g. 6 million mental defectives in the USA, and stressed the multiplicity of factors often involved. Low intelligence could be considered 'physiological' (i.e. analogous with low height), or 'pathological', but in practice it might be impossible to make a hard and fast distinction between the two. In order to illustrate this thesis he recounted a detailed case history. A child born at 36 weeks, with low genetic endowment, developed hypoglycemia. At 3 months he developed infantile spasms. At 2 years an elevated level of blood lead and of antibodies to cytomegalovirus were reported. At 4 years of age the child's mental age was 18 months. Professor Tizard then admitted this case to be of his own invention, but felt that it gave a graphic illustration of the complexity of the situations commonly presenting.

Locomotor Disorders in Childhood Professor A E Claireaux (Hospital for Sick Children, Great Ormond Street, London WCI) described three CNS conditions affecting the newborn: kernicterus, subependymal intraventricular hemorrhage, and a group who had fits and clonic spasms and died of cystic encephalomalacia. He then surveyed the complex field of muscle disorders and their investigation. Under denervation atrophy he included acute anterior poliomyelitis, acute polyneuritis and Werdnig-Hoffmann disease. From the large number of genetically determined myopathies he made special mention of the pseudohypertrophic (Duchenne) type as a 'possibly neural' lesion, and of Pompe's disease (glycogen storage). He illustrated the fine structural abnormalities which

are likely to be of importance in future classification of the myopathies, especially changes in mitochondria.

The Leukodystrophies Dr Magda Erdohazi (Hospital for Sick Children, Great Ormond Street, London WCJ) defined leukodystrophy as an inherited progressive degeneration of cerebral white matter and, following Blackwood (1957), classified cases on a histochemical basis into three main groups: sudanophilic; PAS-positive nonmetachromatic (globoid cell type of Krabbe); and metachromatic (disorder of sulphatide). The basis of the latter two conditions has now been established as lysosomal enzyme deficiency. Most cases are inherited as autosomal recessives. Metachromatic leukodystrophy (sulphatide lipidosis) is due to deficiency in the enzyme aryl sulphatase A. Sulphatide material accumulates in myelin sheaths, Schwann cells, nerve cells and visceral organs. No sudanophilic material is found. In globoid cell leukodystrophy - a disease mainly of young infants - the conspicuous microscopical feature is the presence of large 'globoid' cells filled with material staining strongly with periodic acid-Schiff. The enzyme deficiency, that of galactocerebroside ,B galactoside, has recently been discovered. The presumed macrophage origin of the globoid cells is supported by electron microscopical studies which have shown pseudopodia and no glial fibres. In sudanophilic leukodystrophy bright staining sudanophilic material accumulates in the demyelinated areas. It is likely that diverse pathological processes can produce this picture. One type of inherited sudanophilic (Pelizaeus-Merzbacher) leukodystrophy is characterized by the relative preservation of perivascular myelin. An

Locomotor disorders in childhood.

35 Volume 68 September1975 561 Section of Pathology President J W Stewart MB Meeting 11 February 1975 The Pathology of Neurological Deficit Etiolo...
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