Morphological and clinical analysis of extra-intracranial bypass. 2. Histological and histometrical evaluation with correlation of angiographical findings.

Rest segments of superficial temporal arteries obtained during STA-MCA anastomoses were studied histologically and histometrically. Aging was found to be associated with thickening of the intimal layer and thinning of the medial layer. In comparison with the young patients, the old patients showed a larger internal diameter of the superficial temporal artery and a larger ratio of the thickness of the intimal layer to the medial layer. The internal diameter calculated angiographically and the internal diameter estimated histologically correlated well. The dilatation ratio of the superficial temporal artery did not correlate with dimensional data assessed histologically.