CLINICAL IMPORTANCE OF THE SUPRA-ISTHMIC ANASTOMOSIS BETWEEN THE SUPERIOR THYROID ARTERIES IN 6 CASES OF OCCLUSION OF THE COMMON CAROTID-ARTERY

In six cases of occlusion of a single common carotid artery, antegrade blood flow was demonstrable in the ipsilateral internal carotid arter y by doppler ultrasonography. Antegrade blood flow was also observed i n the intracranial portion of the internal carotid artery, comparative ly reduced and irregular with respect to that of the corresponding con tralateral artery. Studies by color doppler ultrasound and digital sub traction angiography revealed the presence of a collateral arch that p assed through the supra-isthmic anastomosis between the superior thyro id arteries. All six subjects examined had presented with neurological deficits that subsequently almost completely regressed. The regressio n of symptomatology indicates the clinical importance of the collatera l circle.