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Original research
The ’bendy' basilar: progressive aneurysm tilting and arterial deformation can be a delayed outcome after coiling of large basilar apex aneurysms
  1. Ansaar T Rai1,
  2. Abdul R Tarabishy2,
  3. SoHyun Boo1,3,
  4. Jeffrey S Carpenter1,
  5. Sanjay Bhattia
  1. 1 Department of Interventional Neuroradiology, West Virginia University Hospital, Morgantown, West Virginia, USA
  2. 2 Department of Neuroradiology, West Virginia University, Morgantown, West Virginia, USA
  3. 3 Department of Neurosurgery, West Virginia University, Morgantown, West Virginia, USA
  1. Correspondence to Dr Ansaar T Rai, Department of Interventional Neuroradiology, West Virginia University, Morgantown, WV 26506, USA; ansaar.rai{at}


Background Morphological changes in the basilar artery and the artery-aneurysm relationship following coiling of large basilar apex aneurysms may induce morbidity.

Methods The basilar artery radius-of-curvature was measured along its center line on volumetrically reconstructed images formatted along the plane of curvature. The aneurysm-tilt-angle was measured between the distal basilar and the vertical long axis of the aneurysm. The measurements were compared between small (<10 mm) and large (≥10 mm) aneurysms on baseline and follow-up studies. The volume (mm3) and mass (g) of the deployed coils was also compared.

Results Among 94 consecutive aneurysms, 62 (66%) were <10 mm and 32 (34%) were ≥10 mm. The mean aneurysm size and volume was 9 mm (±4) and 507 mm3(±1366) respectively. The median aneurysm follow-up was 24 months (IQR 6–59). There was no difference between the groups based on age, gender, or associated comorbidities. The coil mass was 0.4 g (±0.2) for aneurysms <10 mm and 1.9 g (±1.6) for aneurysms ≥10 mm (P<0.0001). The total coil volume was 32 (±20) mm3 for aneurysms <10 mm and 187 (±172) mm3 for aneurysms ≥10 mm (P<0.0001). Aneurysms ≥10 mm tilted 13.5o (±14.4) compared with 1.1o (±2.8) for aneurysms <10 mm (P<0.0001). The basilar artery became more curved by 1.3 (±9.4) mm for aneurysms ≥10 mm and 0.25 (±2.1) mm for aneurysms <10 mm (P=0.0002). Other than size of the coiled aneurysms no other factors correlated with the geometrical changes.

Conclusion Large coiled basilar apex aneurysms may be more prone to aneurysm tilting and bending of the basilar artery. Speculative causes include the weight of the coil mass and the biomechanical forces exerted on the coiled aneurysm.

  • aneurysm
  • coil
  • complication

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  • Contributors AR, AT: study design, data analysis, manuscript preparation. AT, SB, JC, SB: data collection.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial, or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent Not required.

  • Ethics approval Institutional Review Board.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement There is no additional supplemental data.