Open access Review Multimodal management of giant cerebral aneurysms: review of literature and case presentation Jessica K Campos ,1 Benjamin Z Ball,1 Barry Cheaney II ,2 Alexander J Sweidan,3 Bima J Hasjim,1 Frank P K Hsu,1 Alice S Wang,4 Li- Mei Lin 5 To cite: Campos JK, Ball BZ, ABSTRACT and re- organisation by fibroblasts.3 These Cheaney II B, et al. Multimodal The pathophysiology of giant cerebral aneurysms renders fibroblasts produce connective tissue that management of giant cerebral them difficult to treat. Advances in technology have aneurysms: review of literature reinforces the wall while still permitting it to attempted to address any shortcomings associated 4 5 and case presentation. Stroke grow. These recurrent haemorrhages have with open surgery or endovascular therapies. Since & Vascular Neurology 2020;5: been postulated to be the cause of a giant the introduction of the flow diversion technique, the e000304. doi:10.1136/svn- aneurysm’s slower growth rates compared 2019-000304 endovascular approach with flow diversion has become 6 the first- line modality chosen to treat giant aneurysms. A with smaller aneurysms. Certain locations, Received 18 November 2019 subset of these giant aneurysms may persistent despite such as the ophthalmic and cavernous Revised 18 February 2020 any treatment modality. Perhaps the best option for these segments of the internal carotid artery (ICA), Accepted 27 February 2020 recurrent and/or persistent giant aneurysms is to employ a are more likely to allow for the development Published Online First multimodal approach—both surgical and endovascular— of giant aneurysms due to the adjacent ante- 15 March 2020 rather than any single technique to provide a curative rior clinoid process as well as the dura of the result with favourable patient outcomes. This paper cavernous sinus which each partially shield provides a review of the histopathology and treatment the aneurysm dome and buttress it against options for giant cerebral aneurysms. Additionally, an haemodynamic forces that might otherwise illustrative case is presented to highlight the unique cause rupture.7 challenges of a curative solution for giant cerebral aneurysms that persist despite initial treatment. TREatMENT OPTIONS INTRODUCTION Microsurgical techniques Giant cerebral aneurysms (>25 mm) may Microsurgical intervention for giant aneu- © Author(s) (or their be treated via endovascular or microsur- rysms has been reported dating back to the employer(s)) 2020. Re- use 8 permitted under CC BY- NC. No gical means, with each approach having its 1950s. It has varying success depending commercial re- use. See rights own benefits, risks and technical challenges. on the specific intervention selected, with and permissions. Published by They represent an extremely complicated the most common being clipping or aneu- BMJ. subset of aneurysm pathology. Giant aneu- rysm trapping with extracranial–intracranial 1 Department of Neurosurgery, rysms may require a multimodal approach bypass. Mortality has been reported at least University of California Irvine 6% and up to 13%, whereas favourable clin- Medical Center, Orange, combining both endovascular and microsur- California, USA gical approaches to achieve the best possible ical outcomes range from 71% to 80% in most 9–12 2Oregon Health & Science outcomes. series. University, School of Medicine, Gewirtz and Awad reported the results of 35 Portland, Oregon, USA 3 patients treated with microsurgical clipping Department of Neurology, PatHOPHYSIOLOGY for giant aneurysms of the anterior circu- University of California Irvine Medical Center, Orange, Giant aneurysms, defined as >25 mm, are lation. Twenty- six (68%) of these patients California, USA histopathologically distinct. They have a loss presented with subarachnoid haemorrhage. 4Western University of Health of type I collagen and fibronectin in the adven- Thirty- three were treated with one or more Sciences, College of Osteopathic titia and muscularis mucosa, respectively.1 clips across the aneurysm neck, and two were Medicine of the Pacific, Pomona, Constant blood pulsations weaken the vessel treated with aneurysm trapping. Thirty- four California, USA 5Carondelet Neurological wall, degenerate the internal elastic lamina of 35 (97%) giant aneurysms were completely 2 Institute, St Joseph’s Hospital, and stretch the aneurysm dome. Scarring obliterated and patency of all of the parent Carondelet Health Network, of the aneurysm wall results from the forma- arteries was achieved in 30 cases (86%). The Tucson, Arizona, USA tion of thrombi within the wall and laminar clinical outcome, as defined by authors, was Correspondence to necrosis. In addition, frequent microhaemor- 34% ‘excellent’, 37% ‘good’, 14% ‘fair’, 9% Dr Li- Mei Lin; rhages in the aneurysm wall from parasitised ‘poor’ and 6% ‘death’. Nine patients suffered drlimeilin@ gmail. com vasa vasorum are subject to encapsulation neurological morbidity and mortality was 6% 22 Campos JK, et al. Stroke & Vascular Neurology 2020;5:e000304. doi:10.1136/svn-2019-000304 Open access with good or excellent clinical outcomes in 71%.10 Simi- 5%–25% risk of ischaemic stroke after parent vessel sacri- larly, Nanda et al conducted a study of 59 giant aneurysms fice secondary to haemodynamic and thromboembolic treated by surgical clipping by a single surgeon. Forty- eight causes. Both a BTO without the development of neuro- had anterior circulation and 11 had posterior circulation logical deficit and a transcranial Doppler demonstrating aneurysms. The mortality rate was 10.1% (11 patients). no >30% drop in the middle cerebral artery velocity from The majority (71.9%) experienced a good outcome baseline should be demonstrated prior to embolisation.23 (Glasgow Outcome Score (GOS) of 4 or 5). Predictors Complications related to BTOs with associated vessel of the poor outcome included ruptured aneurysm, poor sacrifice include transient ischaemic attacks from relative clinical outcome and posterior location.12 Additionally, in ischaemia, thromboembolic strokes and development of Cantore et al’s series on 58 patients with giant aneurysms aneurysms.24 treated with surgical clipping, the mortality rate was 6.9% and clinical improvement 94.4%.9 Coil embolisation Microsurgical clip reconstruction requires some form Coil embolisation of giant cerebral aneurysms is associ- of aneurysmal neck, even if it is broad and fenestrated or ated with significantly high retreatment rates. Chalouhi encircling clips can be implemented for reconstruction. et al studied 334 large and giant aneurysms (80% ante- The option of bypass must be entertained if clip deploy- rior circulation) that were coiled at a single institution. ment obstructs the patency of one or more arteries. Thirty- two (10%) were giant aneurysms. Recanalisa- Temporary trapping is required along with blood pres- tion and retreatment rates were 39% and 33%, respec- sure augmentation in order to enhance collateral flow tively.25 Recanalisation is highest in the setting of wide while temporary clips are placed. The aneurysm can residual aneurysm necks, largely due to coil compac- then be punctured and decompressed, however, if a tion, growing residual aneurysm neck, and refilling significant thrombus is present, endoaneurysmectomy fundus.3 26 27 Fernandez et al series with 51 wide- necked must be performed.13 Multiple bypass approaches exist aneurysms (necks>4 mm) treated with coil embolisation including direct vessel reimplantation, side-to- side vessel reported complete thrombosis was observed in only anastomosis, low- flow extracranial- intracranial bypass and 15%.28 Additionally, Horowitz et al’s retrospective study high- flow extracranial–intracranial (EC-IC) bypass.14–18 A evaluating aneurysm recurrences or subtotal initial coil bypass is done under burst suppression and temporary embolisation found seven of the nine patients requiring clip occlusion. Once the bypass is complete, patency is repeat treatment were secondary to coil compaction.26 verified via the micro- Doppler technique along with an Comparatively, Hasan et al demonstrated in a study of 175 intraoperative angiogram. The aneurysm is then subse- coiled aneurysms, 8 had major recurrences resulting from quently treated during the same operation via trapping or significant aneurysm sac growth (15% to 102% increase), occlusion. If proximal occlusion were to obstruct branch independent of change in coil volume.27 vessels or perforators, distal occlusion can be done.19 20 Vascular reconstruction devices (VRD), such as Neuro- Cantore et al reported results on 41 patients with giant form Atlas Stent (Stryker Neurovascular, Fremont, Cali- aneurysms managed with high- flow EC- IC bypass. Four fornia, USA), Low- profile Visualised Intraluminal Support (9.8%) died and 34 (91.9%) improved. Graft patency at (LVIS; Microvention, Tustin, California, USA) and the follow- up examination was 92.7%.9 PulseRider (Cerenovus, Irvine, California, USA), were The use of deep hypothermic circulatory arrest with designed to augment coil embolisations of wide-neck aneu- microsurgical clipping or bypass approaches is a modality rysms. An in vitro study demonstrated that these devices that has waned in popularity. The procedure has an unpre- reinforce embolisation by improving coil neck coverage dictable recovery after circulatory arrest, with treatment and increasing coil packing density.29 Both LVIS Jr and complications approaching 40% with an additional 20% Neuroform Atlas stents provide low profile advantages medical