Regarding “Clinical and Imaging Follow-Up of Patients with Coiled Basilar Tip Aneurysms Up to 20 Years”

We thank van Eijck et al for their effort in addressing the important, relevant question regarding the follow-up on coiled basilar aneurysms in “Clinical and Imaging Follow-Up of Patients with Coiled Basilar Tip Aneurysms Up to 20 Years.”¹ However, we would like to raise a few questions regarding the study.

In this long-term follow-up study of patients with coiled basilar aneurysms, the authors concluded that regular and life-long follow-up should be done, possibly with yearly MR imaging, to detect reopening in a timely manner, because even stable occluded aneurysms can reopen and rebleed many years after treatment. However, it is unclear from the data presented how many of the aneurysms reopened or regrew and whether growth was progressive on follow-up. Were all patients with reopening treated? Retreatment statistics may not accurately indicate how many of these aneurysms reopened or regrew unless all of these were retreated. Chalouhi et al² reported a much higher recanalization rate (17.2% in stented and 38.9% in nonstented aneurysms) versus retreatment rates (7.8% in stented and 27.8% in nonstented aneurysms) in 235 cases of coiled basilar tip aneurysms.

The study provides valuable insight, and it would be very helpful to have a few more questions answered.

In the 9 patients who rebled (and 3 who died), did follow-up imaging help in predicting the event? Did any of these cases show evidence of reopening or regrowth on imaging?

Progressive mass effect was seen in 6 patients and was the cause of death in 5 patients. Four of these had multiple retreatments, and 3 had 5 retreatments. Did repeat coiling have any correlation with progressive mass effect? Was the mass effect on the brain stem or optic chiasm not manifested clinically? Were there any brain stem signs or clinical nerve dysfunction that warranted further imaging?

Unruptured treated aneurysms did not bleed on follow-up. Did they increase in size? Do they need to be followed up? Did any of them need retreatment?

The authors report that the aneurysm size was the most important risk factor for retreatment, and this finding is consistent with the literature. It would be interesting to know whether and how many of the small (<10 mm) aneurysms regrew and whether they were retreated.

While imaging is helpful to document reopening/regrowth, it is unclear whether routine imaging in all patients and annual imaging would necessarily add value. Imaging might also lead to more aggressive retreatment. More data to show that it could actually help prevent rebleeds would be helpful. While all the retreatments in the authors' study did not have complications, other studies have described a roughly 6% rate of thromboembolic complications both with and without stent assistance.²

• © 2016 by American Journal of Neuroradiology