Central Nervous System

Degenerative diseases of the nervous system in children are acknowledged to be chronic (usually) and destructive (invariably), and for the biochemically oriented clinician they provide a challenging interest because most are genetically, and probably, therefore, chemically determined. Individually relatively rare, most of them are inherited as autosomal recessive conditions, and by implication may represent the clinical effects of inborn metabolic errors. Nevertheless only a minority at present are thus identified because, except where there is an easily recognizable storage product such as ganglioside, or abnormal metabolic cumulation readily identifiable in body fluids such as amino acid, it is usually very difficult to guide biochemical research on purely clinical and pathological indications. It is still necessary and possible, however, to give an accurate prognosis and genetic analysis without any biochemical information, but biochemical refinements offer the opportunity of delineating syndromes which at a given point in time are clinically indistinguishable, e.g. Tay-Sachs variants, and this may be important in genetic counselling. In a few conditions biochemical identification of fetal tissues enables a more constructive opportunity for eugenic measures. At the present stage of our knowledge, and with perennial economic limitations on screening measures, a discriminating use of elaborate biochemical techniques is desirable and it is proposed to review a scheme of investigation which depends for its usefulness upon a careful clinical appraisal, and therefore is applicable to conditions which are not identifiable chemically as well as those that are. Abroad neuropathological classification of heredodegenerative neurological diseases is presented in Table I. TABLE I Neuropathological Classification of Heredodegenerative Neurological Diseases