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LETTER TO EDITOR
Year : 2014  |  Volume : 62  |  Issue : 4  |  Page : 455-457

Pipeline stents for partially thrombosed posterior circulation aneurysms: A word of caution!


1 Department of Neurosurgery, Nizam's Institute of Medical Sciences, Hyderabad, Andhra Pradesh, India; Division of Neurosurgery, Sunnybrook Health Sciences Centre, University of Toronto, Ontario, Canada
2 Division of Neurosurgery, Sunnybrook Health Sciences Centre, University of Toronto, Ontario, Canada

Date of Web Publication19-Sep-2014

Correspondence Address:
Ashish Kumar
Department of Neurosurgery, Nizam's Institute of Medical Sciences, Hyderabad, Andhra Pradesh, India; Division of Neurosurgery, Sunnybrook Health Sciences Centre, University of Toronto, Ontario, Canada

Ashish Kumar
Department of Neurosurgery, Nizam's Institute of Medical Sciences, Hyderabad, Andhra Pradesh, India; Division of Neurosurgery, Sunnybrook Health Sciences Centre, University of Toronto, Ontario, Canada

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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.141268

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How to cite this article:
Kumar A, Yang V, Dacosta L, Kumar A, Yang V, Dacosta L. Pipeline stents for partially thrombosed posterior circulation aneurysms: A word of caution!. Neurol India 2014;62:455-7

How to cite this URL:
Kumar A, Yang V, Dacosta L, Kumar A, Yang V, Dacosta L. Pipeline stents for partially thrombosed posterior circulation aneurysms: A word of caution!. Neurol India [serial online] 2014 [cited 2020 Oct 31];62:455-7. Available from: https://www.neurologyindia.com/text.asp?2014/62/4/455/141268


Sir,

A 59-years-old lady presented with complaints of recent headaches and double vision. Examination revealed right partial third nerve palsy. Magnetic resonance imaging (MRI) of head showed a globular hemorrhagic lesion (14 Χ 16 Χ 18 mm) in the interpeduncular region on the right side pressing on the right crus. Cerebral angiogram showed a large partially thrombosed right P1-P2 segment posterior cerebral artery (PCA) aneurysm [Figure 1]. The high location of the lesion, reaching up to the third ventricle, made direct clipping difficult. Other surgical options were considered, such as distal PCA bypass and proximal occlusion, and endovascular coiling-both considered high risk in this situation. Therefore, we opted to use a Pipeline Embolization Device (PED) to occlude the aneurysm with flow diversion.

Patient underwent successful deployment of two pipeline stents co-axially to cover the entire length of the neck and no major branches covered [Figure 2], and discharged subsequently without any complications. Her complaints of double vision improved for period of time, but recurrent worsening of the double vision lead to two admissions in the next 3 weeks. MRI showed increasing size of the aneurysm along with further thrombosis causing increased vasogenic edema around the aneurysm and mass effect [Figure 3]. This was interpreted as a reaction to clotting in the aneurysm sac, and she was started on steroids, improving on both occasions. Four weeks after treatment she presented with sudden onset left hemiparesis. Computed tomography angiography (CTA) showed no clot in the right PCA, however it showed new hemorrhage into the aneurysm and extension into the posterior third ventricle [Figure 4]. A small filling of the aneurysm neck could be seen through the stent. Patient was admitted into the critical care unit (CCU) and options were being discussed with the family in terms of; (a) Deploying a new stent within the area of leak or (b) sacrificing the right PCA/surgical clipping with debulking and aneurysmorraphy. Unfortunately within 30 minutes of the CTA patient blew both pupils and CT [Figure 5] showed massive brainstem hemorrhage and intraventricular hemorrhage (IVH). External ventricular drains were inserted as a last resort but patient succumbed the very next day.
Figure 1: MRI showing the real size of thrombosed PCA aneurysm while cerebral angiogram showing only partial filling of the lumen while the aneurysm can be seen arising from P1-P2 segment of PCA

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Figure 2: (a and b) Cerebral angiogram done after 6 days showing increased fi lling of aneurysm, (c) 3D angiogram showing the aneurysmal morphology, (d) Post stent deployment 3D spin showing stasis in the aneurysm, (e) CTA post procedure showing the stent across the neck of the aneurysm

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Figure 3: Interval MRI showing increased mass effect and surrounding vasogenic edema in the brainstem

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Figure 4: (a and b) CT showing increasing hemorrhage in the aneurysm after 4 weeks of procedure with early signs of hemorrhage in the third ventricle (white arrow). (c) CTA showing leak of contrast across the stent
into the aneurysm (red arrow)


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Figure 5: Catastrophic hemorrhage into the brainstem along with intraventricular hemorrhage

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Pipeline embolization devices have stormed the endovascular arena in last few years [1] and chiefly their use has been limited to the anterior circulation. With increasing experience, unexpected complications have been reported, being the most common delayed parenchymal hemorrhage and rupture of apparently well-treated large or giant aneurysms. Kuzmik et al., [2] described two paraophthalmic aneurysms treated with SILK stents™ where one of aneurysms occluded completely while the other one ruptured. Hampton et al., have described this process of mural destabilization in two different anterior circulation aneurysms [3] hypothesizing that this phenomenon is responsible for continuous growth of treated aneurysms, which may become symptomatic in the early or late period after treatment.

The possible explanations of continuous growth of thrombosed aneurysms are parasitization of aneurysm by vasa vasorum, [4] with the formation of a continuous cycle of hemorrhage and thrombosis of vasa vasorum, leading to increase in the size even when the aneurysm is completely excluded from the circulation and no flow is seen within the sac. Clinico-pathologic studies suggest that the deployment of PEDs in a partially thrombosed aneurysm can increase the risk of rupture in weak points in the vessel wall already covered by thrombus. Lack of wall nutrition due to overlying thrombus might be the underlying reason. [5]

Ding et al., reported a giant PCA circulation aneurysm which was quite similar to our patient where the PED occluded at the proximal end while the aneurysm kept on causing increased mass effect, ultimately being excised surgically. [6] Similarly to the aneurysm growth after apparently successful treatment with PED, cases of delayed intraparenchymal hemorrhage [7],[8] have been reported but the exact mechanism is still unknown.

In summary, PEDs are, as advertised, a revolution in the treatment of intracranial aneurysms. There is growing evidence that they might play a major role in treatment of aneurysms, with the bulk of the experience in the anterior circulation. Its use in the posterior circulation is still related to a higher complication rates. [9] However, it should be kept in mind that device deployment is technically demanding, with proper training/supervision being a real need. As the experience with PED grows, we become familiar with previously unknown complications, such as growth of apparently occluded aneurysms and delayed hemorrhage remote from the index aneurysm, and despite many hypotheses, we do not have a definitive answer to these questions. The device should be seen as another tool in cerebrovascular surgery, not as a panacea. Use in aneurysms amenable to more established techniques, either open or endovascular, should be promoted with caution, within an investigative, regulated environment to be able to provide accurate information about the device's efficacy and maybe change definitively the landscape of cerebrovascular neurosurgery.

 
  References Top

1.Lylyk P, Miranda C, Ceratto R, Ferrario A, Scrivano E, Luna HR et al. Curative endovascular reconstruction of cerebral aneurysms with the pipeline embolization device: The Buenos Aires experience. Neurosurgery 2009;64:632-42.  Back to cited text no. 1
    
2.Kuzmik GA, Williamson T, Ediriwickrema A, Andeejani A, Bulsara KR. Flow diverters and a tale of two aneurysms. J Neurointerv Surg 2013;5:e23.  Back to cited text no. 2
    
3.Hampton T, Walsh D, Tolias C, Fiorella D. Mural destabilization after aneurysm treatment with a flow-diverting device: A report of two cases. J Neurointerv surg 2011;3:167-71.  Back to cited text no. 3
    
4.Dehdashti AR, Thines L, Willinsky RA, Tymianski M. Symptomatic enlargement of an occluded giant carotido-ophthalmic aneurysm after endovascular treatment: The vasa vasorum theory. Acta Neurochir (Wien) 2009;15:1153-8.  Back to cited text no. 4
    
5.Chow M, McDougall C, O'Kelly C, Ashforth R, Johnson E, Fiorella D. Delayed spontaneous rupture of a posterior inferior cerebellar artery aneurysm following treatment with flow diversion: A clinicopathologic study. AJNR Am J Neuroradiol 2012;33:E46-51.  Back to cited text no. 5
    
6.Ding D, Starke RM, Liu KC. Microsurgical strategies following failed endovascular treatment with the pipeline embolization device: Case of a giant posterior cerebral artery aneurysm. J Cerebrovasc Endovasc Neurosurg 2014;16:26-31.  Back to cited text no. 6
    
7.Cruz JP, Chow M, O'Kelly C, Marotta B, Spears J, Montanera W, et al. Delayed ipsilateral parenchymal hemorrhage following flow diversion for the treatment of anterior circulation aneurysms. AJNR Am J Neuroradiol 2012;33:603-8.  Back to cited text no. 7
    
8.Velat GJ, Fargen KM, Lawson MF, Hoh BL, Fiorella D, Mocco J. Delayed intraparenchymal hemorrhage following pipeline embolization device treatment for a giant recanalized ophthalmic aneurysms. J Neurointerv Surg 2012;4:e24.  Back to cited text no. 8
    
9.Phillips TJ, Wenderoth JD, Phatouros CC, Rice H, Singh TP, Devilliers L, et al. Safety of the pipeline embolization device in treatment of posterior circulation aneurysms. AJNR Am J Neuroradiol 2012;33:1225-31.  Back to cited text no. 9
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]

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