We employed 6-fluorodopa to study the integrity of the nigrostriatal dopaminergic projection by positron emission tomography in 4 subjects with clinical features of mild parkinsonism caused by exposure to manganese. The 6-fluorodopa scans were normal. This finding suggests that in early manganism sufficient to cause parkinsonian deficits, damage may occur in pathways postsynaptic to the nigrostriatal system, probably involving striatal or pallidal neurons. Fluorodeoxyglucose scans showed decreased cortical glucose metabolism, the significance of which is discussed.

Given the abundant and, at times, contradictory studies of ventricular enlargement in neurological and psychiatric disorders, the current study was carried out to provide an empirical basis for analysing and interpreting these measures. A sample of CT scans on 100 control subject was drawn from the files of the University of British Columbia Department of Radiology and 19 measures of ventricular and head diameter or area were made. The interrelationships of these measures were then examined using factor analytic procedures. Three ventricular dimensions were found. To validate these three dimensions, the relationship of each with age was examined and then the agecorrected scores of seven clinical groups were compared on each of these dimensions. The magnitude of the relationship between these dimensions and age was impressive and each dimension contributed unique information regarding these age-related changes. Moreover, the analysis of the clinical groups suggested that differential patterns of ventricular change were present dependent upon the disease. These results are discussed with a view to integrating the findings of previous studies and planning future studies. The first purpose of this study was to discover if different measures of ventricular area or diameter provide similar or different information on ventricular enlargement. Therefore, 13 measures of ventricular area or diameter (nine area and four linear measures) and six measures of head area or diameter (three linear and three area measures) derived from the CT scans of 100 normal subjects aged 18 to 79 were factor analysed to find out the number of ventricular dimensions underlying these measures. As many studies in the literature report a strong relationship between age and different measures of ventricular system, 9 the second purpose of the study was to discover the relationship between age and different ventricular measures. The primary question was whether specific measures provided unique information on the normal ventricular changes with ageing. This question was addressed by predicting age from the 13 ventricular measures using a step-wise multiple regression analysis. Department ofThe final purpose of the current study was to validate these dimensions clinically by determining if unique profiles of ventricular change were present in different neurological and psychiatric conditions. These specific measures for each ventricular dimension as identified by factor analysis were used to generate regression equations predicting the age of the normal subjects and these regression equations were used to predict age in the clinical groups. The residuals or the number of years their predicted age differed from their actual age were then analysed using analysis of variance procedures to see if different disorders had characteristic profiles of abnormal ventricular enlargement. The patient sample consisted of 70 patients representing seven diagnostic categories, as follows: 1) dementia of unknown origin; 2) multiple sclerosis; 3) Parkinson's ...

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