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

A. Malhotra, X. Wu, V.B. Kalra
Department of Diagnostic Radiology

C.C. Matouk
Department of Neurology and Neurosurgery

H.P. Forman
Department of Diagnostic Radiology
Yale School of Medicine
New Haven, Connecticut

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


  1. van Eijck M, Bechan RS, Sluzewski M, et al. Clinical and imaging follow-up of patients with coiled basilar tip aneurysms up to 20 years. AJNR Am J Neuroradiol 2015;36:2108–13
  2. Chalouhi N, Jabbour P, Gonzalez LF, et al. Safety and efficacy of endovascular treatment of basilar tip aneurysms by coiling with and without stent assistance: a review of 235 cases. Neurosurgery 2012;71:785–94


W.J. van Rooij, M. van Eijck, R. Bechan, G. Roks
St. Elisabeth Ziekenhuis
Tilburg, the Netherlands

We thank our colleagues Malhotra et al for their interest in our long-term follow-up study in patients with coiled basilar tip aneurysms. We thank the Editor for the opportunity to address their questions.

Our follow-up study of a patient cohort of 154 coiled basilar tip aneurysms covered 20 years. No patients were lost to clinical follow-up, and most eligible patients had imaging follow-up at various times. Nevertheless, imaging follow-up was not structured in yearly intervals; therefore, some questions remain unanswered. On the other hand, our study has the longest follow-up and is the most complete in the literature up to now, to our knowledge.

We will try to answer the questions raised by Malhotra et al. As we indicated in the “Materials and Methods” section, any reopening was an indication for additional coiling. Only exceptionally was additional treatment not performed or postponed for technical anatomic or clinical reasons.

Of 9 patients with a rebleed from the coiled ruptured basilar tip aneurysm, 2 died from an initial incompletely occluded aneurysm before 6-month follow-up imaging was performed. In 5 patients, previous follow-up imaging showed a completely occluded aneurysm (for an example, see Fig 2). The 1 patient with a rebleed 16 years after coiling underwent CT at another hospital 2 years earlier, but in retrospect, visible reopening was not appreciated at the time.

Progressive growth of the basilar tip aneurysm was the most devastating event in our patient cohort, directly leading to death in 5 of 6 patients. Multiple additional coiling had no favorable effect on the progressive increase in size of these aneurysms at an unpredictable pace. In the “Discussion,” we addressed the clinical presentation of mass effect on the brain stem and cranial nerves. Most patients presented with gradually progressive cognitive decline, with apathy, dysphagia, fatigue, and gait disturbances. In a later phase, locked-in syndrome occurred in 1 patient. The patient with optic chiasm compression had visual field deficits and headaches.

The most important predictor for reopening of the coiled basilar tip aneurysm is aneurysm size. Larger aneurysms reopen more frequently. However, small aneurysms may also reopen. In our cohort, 11 of 37 (30%) retreated basilar tip aneurysms were 2–9 mm. Two of 11 aneurysms were unruptured. Three of 9 reopened ruptured small aneurysms had a recurrent hemorrhage.

Our study does not provide answers to all questions relating to reopening and rebleeding at follow-up of coiled basilar tip aneurysms. However, one thing is certain: Reopening (and rebleeding) of coiled basilar tip aneurysms is unpredictable. Although some trends are apparent, they are of limited value to the individual patient. Larger aneurysms reopen more frequently, but small aneurysms may also reopen. While most reopening becomes evident in the first year of follow-up, reopening may also occur many years after first or repeated treatment and after long periods of stable complete occlusion.

In our opinion, yearly MR imaging of all coiled basilar tip aneurysms should be adequate to detect this, to some extent unpredictable, reopening in a timely manner. Recurrent episodes of hemorrhage can thus be prevented.

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