Change in the angle of the anterior genu is associated with occlusion rate after Pipeline flow diversion

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The Pipeline embolization device (PED) is a self-expanding mesh stent that diverts blood flow away from an aneurysm; it has been successfully used to treat aneurysms of the proximal internal carotid artery (ICA). PEDs have a remarkable ability to alter regional blood flow along the tortuous segments of the ICA and were incidentally found to alter the angle of the anterior genu after treatment. The authors quantified these changes and explored their implications as they relate to treatment effect.


The authors retrospectively reviewed cases of aneurysms treated with a PED between the ophthalmic and posterior communicating arteries from 2012 through 2015. The angles of the anterior genu were measured on the lateral projections of cerebral angiograms obtained before and after treatment with a PED. The angles of the anterior genu of patients without aneurysms were used as normal controls.


Thirty-eight patients were identified who had been treated with a PED; 34 (89.5%) had complete obliteration and 4 (10.5%) had persistence of their aneurysm at last follow-up (mean 11.3 months). After treatment, 32 patients had an increase, 3 had a decrease, and 3 had no change in the angle of the anterior genu. The average measured angle of the anterior genu was 36.7° before treatment and 44.3° after treatment (p < 0.0001). The average angle of the anterior genu of control patients was 43.32° (vs 36.7° for the preoperative angle in the patients with aneurysms, p < 0.057). The average change in the angle of patients with postoperative Raymond scores of 1 was 9.10°, as compared with 1.25° in patients with postoperative Raymond scores > 1 (p < 0.001).


Treatment with a PED significantly changes the angle of the anterior genu. An average change of 9.1° was associated with complete obliteration of treated aneurysms. These findings have important implications for the treatment and management of cerebral aneurysm.

ABBREVIATIONS ICA = internal carotid artery; PED = Pipeline embolization device.

Article Information

Correspondence Philipp Taussky: Clinical Neurosciences Center, University of Utah, Salt Lake City, UT.

INCLUDE WHEN CITING Published online January 18, 2019; DOI: 10.3171/2018.9.JNS18726.

Disclosures Dr. Taussky reports a consultant relationship with Medtronic.

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Schematic of the effect of the Pipeline flow diverter on the angle of the anterior genu. A: Preoperative. B: Postoperative. Figure is available in color online only.

  • View in gallery

    Cerebral angiogram obtained in a 78-year-old woman with a cavernous ICA aneurysm. A: The angle of the genu before PED treatment was 22°. B: The angle 1 year after PED treatment was 42°.


  • 1

    Becske TBrinjikji WPotts MBKallmes DFShapiro MMoran CJ: Long-term clinical and angiographic outcomes following Pipeline Embolization Device treatment of complex internal carotid artery aneurysms: five-year results of the Pipeline for Uncoilable or Failed Aneurysms Trial. Neurosurgery 80:40482017

  • 2

    Becske TKallmes DFSaatci IMcDougall CGSzikora ILanzino G: Pipeline for uncoilable or failed aneurysms: results from a multicenter clinical trial. Radiology 267:8588682013

  • 3

    Bouthillier Avan Loveren HRKeller JT: Segments of the internal carotid artery: a new classification. Neurosurgery 38:4254331996

  • 4

    Dai DDing YHKelly MKadirvel RKallmes D: Histopathological findings following pipeline embolization in a human cerebral aneurysm at the basilar tip. Interv Neuroradiol 22:1531572016

  • 5

    Fischer SVajda ZAguilar Perez MSchmid EHopf NBäzner H: Pipeline embolization device (PED) for neurovascular reconstruction: initial experience in the treatment of 101 intracranial aneurysms and dissections. Neuroradiology 54:3693822012

  • 6

    Ishii AChihara HKikuchi TArai DIkeda HMiyamoto S: Contribution of the straightening effect of the parent artery to decreased recanalization in stent-assisted coiling of large aneurysms. J Neurosurg 127:106310692017

  • 7

    Lin LMColby GPJiang BUwandu CHuang JTamargo RJ: Classification of cavernous internal carotid artery tortuosity: a predictor of procedural complexity in Pipeline embolization. J Neurointerv Surg 7:6286332015

  • 8

    Silva Neto ÂRCâmara RLValença MM: Carotid siphon geometry and variants of the circle of Willis in the origin of carotid aneurysms. Arq Neuropsiquiatr 70:9179212012

  • 9

    Suzuki TTakao HFujimura SDahmani CIshibashi TMamori H: Relationships between geometrical parameters and mechanical properties for a helical braided flow diverter stent. Technol Health Care 25:6116232017

  • 10

    Zou QXue WLin JFu YGuan GWang F: Mechanical characteristics of novel polyester/NiTi wires braided composite stent for the medical application. Results Phys 6:4404462016




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