Histological structural abnormalities of superficial temporal arteries used for extracranial-intracranial anastomosis.

Histological evaluation of the superficial temporal artery resected at the time of extracranial-intracranial anastomosis was performed in 64 consecutive patients. A neuropathologist who was not aware of the medical condition of these patients studied all specimens under light microscopy with hemotoxylin and eosin, Verhoff, and Mallory strains. Intimal proliferation was observed in 62 samples, intimal fibrosis in 56, fragmentation of the internal elastic lamina in 45, splitting of the internal elastic lamina in 41, fragmentation of the media in 38, and fragmentation of the minimal external elastic tissue in 17. Stenosis of the vessel was observed, and graded from 0% to 50%, with a mean of 20%. The development of intraluminal stenosis was considered to be secondary to the development of intimal fibrosis and hyperplasia. The changes observed were progressive and conformed with those previously described; there was no evidence of correlation with sex, diabetes, or hypertension. The implications for the development of occlusion of the anastomosis or stroke, and for patient survival are discussed.