Long-Term Clinical Follow-Up of Therapeutic Internal Carotid Artery Occlusion

I read with interest and congratulations the results of “Long-Term 3T MR Angiography Follow-Up after Therapeutic Occlusion of the Internal Carotid Artery to Detect Possible de Novo Aneurysm Formation,”¹ as well as the opinion regarding management of internal carotid artery (ICA) aneurysms in this day of new intravascular options.

The authors suggest, with accuracy, that no (or little) systematic follow-up data are available on such patients and that publications are anecdotal. We did systematically review our clinical, if not imaging, follow-up experience with therapeutic occlusion of the ICA, with attention to delayed complications of subarachnoid hemorrhage (SAH) and infarct following balloon occlusion of the ICA.² Sixty of 62 patients (97%) who survived at least 6 months (mean, 60 months; median, 112 months) were the basis for analysis. We did use MR angiography (MRA) in the follow-up of patients, but not systematically, and with far less than the 3T MRA quality available to de Gast et al. ¹ The total follow-up period was 468 patient years. Two SAHs due to de novo anterior communicating aneurysms occurred, and these are mentioned in de Gast's article. The incidence of delayed SAH due to de novo aneurysm was 0.4 per 100 patient-years follow-up. We estimated this occurrence (400/100,000) to be 40 times the risk of SAH in the general population and 5 times greater than Miller et al³ suggested might be expected in patients with previous SAH. Perhaps the 109 patient years that de Gast et al reviewed are insufficient to further document this low occurrence rate.

Unfortunately, our manuscript has been lost to the ages in the abyss of nonindexed, short-lived journals, a lesson in itself in scientific documentation methods and an additional caveat to those entertaining thoughts of new journal development.

• Copyright © American Society of Neuroradiology