627allowed demonstration of marked microcirculatory changes occuring during vasospasm which cannot be detected by macroscopic techniques. SUMMARY Twenty-three patients with occlusion of an internal carotid artery hare been followed 5 to 60 months after angiography. None had a later permanent stroke. Eight had delayed TIAs in the occluded internal carotid area, never in another area. In these TIAs the role of the homolateral external carotid artery is emphasized, because in the 8 cases this artery was the main collateral to the occluded internal carotid, and angiography had shown atheromatous stenosis of homolateral external/common carotid arteries or an irregular stump at the site of the occlusion. Hemodynamic and embolic mechanisms are discussed, especially the latter, because of the absence of serere stenosis and eridence of emboligenic plaques. Stroke, Vol 12, No 5, 1981 References

Twenty-five asphyxiated term babies were investigated in order to evaluate the prediction of their neurodevelopmental outcome by means of computerized tomography (CT) as compared to neurological symptoms during the neonatal period. Low density (LD) areas, thought to represent hypoxicischaemic lesions, were assessed quantitatively by means of a LD score based on the extent and degree of LD, the total score ranging from 0-36. Neonatal scans were defined according to the time span elapsed between asphyxia and CT as (1) early CT (day 1-7, n = 15), and (2) intermediate CT (day 9-23: n = 14; day 29: n = 1). The newborns were classified according to the neonatal neurological findings as having mild (n = 8, 32%), moderate (n = 9, 36%), and severe (n = 8, 32%) encephalopathy, following the definition of Sarnat and Sarnat (1976). Among the twenty-two survivors, the follow-up (mean age 19.2 +/- 6.0 mts) revealed fourteen (56%) with normal outcome, two (8%) with transient neurodevelopmental anomalies during the first year, and nine (36%) with permanent abnormalities such as cerebral palsy and/or retardation (mainly global) and/or epilepsy. Early CT scans had no predictive value. Intermediate CT, however, showed distinct variations of LD areas which resulted in an LD score well correlated with the later outcome. In particular, a LD score below 14 characterized every baby who developed normally; a prediction not possible in a reliable way be means of neonatal neurological signs. For all abnormal children, the score correlated with the severity of the later neurodevelopmental disorder, except for one with the latest intermediate CT (day 29).

Hypoxic-ischaemic brain lesions may be detected as low density (LD) areas by means of computerized tomography (CT), but the clinical significance of such LD areas has been controversial. Since timing might be a critical factor, we studied the temporal evolution of LD areas in 9 asphyxiated term babies who had had two or more CT, and compared the changes to the neurodevelopmental outcome. Scans were classified according to the elapsed time after asphyxia as early (day 1-7, n = 6), intermediate (week 2-4, n = 7; week 4-7, n = 3) and late CT (3 months or more, n = 7). In early scans, no, or only ill defined, LD areas were seen in the periventricular region. In intermediate CT's, LD-zones were further diminished in those babies who later were normal. Sharply accentuated LD areas, however, appeared in those who later suffered from neurodevelopmental disorders. These LD areas, probably representing hypoxic-ischaemic lesions, were located periventricularly, extending into the subcortical white matter and the cortex, and usually involved both hemispheres symmetrically. They began to disappear at 4 to 7 weeks in some regions, possibly because of glial proliferation. LD persisting more than 4-7 weeks tended to transform into cyst-like lesions, or marked atrophy. We conclude (1) that hypoxic-ischaemic lesions appear as zones of low density on CT scans performed after the first week and (2) that the extent of such lesions can best be assessed between 9 to 23 days after asphyxia.

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The assessment of medical technologies has to answer several questions ranging from safety and effectiveness to complex economical, social, and health policy issues. The type of data needed to carry out such evaluation depends on the specific questions to be answered, as well as on the stage of development of a technology. Basically two types of data may be distinguished: (a) general demographic, administrative, or financial data which has been collected not specifically for technology assessment; (b) the data collected with respect either to a specific technology or to a disease or medical problem. On the basis of a pilot inquiry in Europe and bibliographic research, the following categories of type (b) data bases have been identified: registries, clinical data bases, banks of factual and bibliographic knowledge, and expert systems. Examples of each category are discussed briefly. The following aims for further research and practical goals are proposed: criteria for the minimal data set required, improvement to the registries and clinical data banks, and development of an international clearinghouse to enhance information diffusion on both existing data bases and available reports on medical technology assessments.