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Fate of Distal False Aneurysms Complicating Internal Carotid Artery Dissection: A Systematic Review

Open ArchivePublished:April 21, 2016DOI:https://doi.org/10.1016/j.ejvs.2016.03.021

      Background

      False aneurysm formation occurs in 13–49% of internal carotid artery dissections (ICADs). In light of the uncertainty regarding the clinical course, expansion rates and optimal treatment of post-ICAD false aneurysms, a systematic review of the literature was undertaken to establish the fate of the nonoperated distal ICA false aneurysm after ICAD.

      Methods

      PubMed/MEDLINE, Embase, and Cochrane databases were systematically searched up to 13 August 2015 for studies reporting clinical outcomes and imaging surveillance in patients who were found to have developed a false aneurysm associated with ICAD, with specific emphasis on the fate of the nonoperated false aneurysm.

      Results

      Eight studies reported on the course/clinical outcome of ICAD-associated false aneurysms in 166 patients. Of these, five of 166 false aneurysms (3%) increased in size; 86 of 166 (52%) remained unchanged in diameter; 35 of 166 (21%) diminished in size; 32 of 166 (19%) resolved completely; three of 166 (2%) thrombosed; and five 166 (3%) were repaired surgically. Another four of 166 (2%) underwent late surgery (0.5–5.0 years later). During the course of surveillance, none of the nonoperated false aneurysms associated with spontaneous ICAD gave rise to any new neurological or compressive symptoms.

      Conclusions

      In this systematic review, >95% of nonoperated false aneurysms affecting the distal internal carotid artery that developed after an ICAD did not increase in size and were not associated with any delayed neurological symptoms suggesting that conservative management and serial surveillance is the optimal mode of treatment. As nearly all studies suffered from serious bias, reporting standards for diagnosis and follow-up are needed in order to better define their natural history.

      Keywords

      The fate of nonoperated false aneurysms complicating internal carotid artery dissections is unknown. This systematic review observed that false aneurysms rarely became symptomatic and rarely increased in size, suggesting that the majority should be treated conservatively. As nearly all studies suffered from serious bias, reporting standards for diagnosis and follow-up are needed in order to better define their natural history.

      Introduction

      Spontaneous or traumatic internal carotid artery dissections (ICADs) result from a tear in the intima of the internal carotid artery (ICA), usually about 2–3 cm above the carotid bifurcation. This leads to accumulation of blood and a separation of arterial layers within the ICA, with the end result being a stenosis (where thrombus in the false lumen partially compresses flow within the true lumen), complete occlusion (if thrombus in the false lumen completely obstructs flow within the true lumen), or false aneurysm formation (where accumulation of blood is subadventitial).
      • Schievink W.I.
      Spontaneous dissection of the carotid and vertebral arteries.
      • Fusco M.R.
      • Harrigan M.R.
      Cerebrovascular dissections—a review part I: spontaneous dissections.
      • Fusco M.R.
      • Harrigan M.R.
      Cerebrovascular dissections: a review. Part II: blunt cerebrovascular injury.
      False aneurysms are reported to complicate 13–49% of all ICADs.
      • Houser O.W.
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      • Sundt Jr., T.M.
      • Baker Jr., H.L.
      • Reese D.F.
      Spontaneous cervical cephalic arterial dissection and its residuum: angiographic spectrum.
      • Mokri B.
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      • Piepgras D.G.
      Spontaneous dissection of the cervical internal carotid artery.
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      • Leclerc X.
      • Lucas C.
      • Godefroy O.
      • Tessa H.
      • Martinat P.
      • Leys D.
      • et al.
      Helical CT for the follow-up of cervical internal carotid artery dissections.
      • Guillon B.
      • Brunereau L.
      • Biousse V.
      • Djouhri H.
      • Levy C.
      • Bousser M.G.
      Long-term follow-up of aneurysms developed during extracranial internal carotid artery dissection.
      • Touze E.
      • Randoux B.
      • Meary E.
      • Arquizan C.
      • Meder J.F.
      • Mas J.L.
      Aneurysmal forms of cervical artery dissection: associated factors and outcome.
      The highest risk period for suffering a stroke after ICAD is the first 7 days,
      • Schievink W.I.
      Spontaneous dissection of the carotid and vertebral arteries.
      • Fusco M.R.
      • Harrigan M.R.
      Cerebrovascular dissections—a review part I: spontaneous dissections.
      • Fusco M.R.
      • Harrigan M.R.
      Cerebrovascular dissections: a review. Part II: blunt cerebrovascular injury.
      • Guillon B.
      • Brunereau L.
      • Biousse V.
      • Djouhri H.
      • Levy C.
      • Bousser M.G.
      Long-term follow-up of aneurysms developed during extracranial internal carotid artery dissection.
      • Touze E.
      • Randoux B.
      • Meary E.
      • Arquizan C.
      • Meder J.F.
      • Mas J.L.
      Aneurysmal forms of cervical artery dissection: associated factors and outcome.
      • Menon R.
      • Kerry S.
      • Norris J.W.
      • Markus H.S.
      Treatment of cervical artery dissection: a systematic review and meta-analysis.
      and the first-line treatment is usually dual antiplatelet or anticoagulant therapy, in order to prevent thromboembolic stroke.
      • Schievink W.I.
      Spontaneous dissection of the carotid and vertebral arteries.
      • Fusco M.R.
      • Harrigan M.R.
      Cerebrovascular dissections—a review part I: spontaneous dissections.
      • Fusco M.R.
      • Harrigan M.R.
      Cerebrovascular dissections: a review. Part II: blunt cerebrovascular injury.
      • Guillon B.
      • Brunereau L.
      • Biousse V.
      • Djouhri H.
      • Levy C.
      • Bousser M.G.
      Long-term follow-up of aneurysms developed during extracranial internal carotid artery dissection.
      • Touze E.
      • Randoux B.
      • Meary E.
      • Arquizan C.
      • Meder J.F.
      • Mas J.L.
      Aneurysmal forms of cervical artery dissection: associated factors and outcome.
      • Menon R.
      • Kerry S.
      • Norris J.W.
      • Markus H.S.
      Treatment of cervical artery dissection: a systematic review and meta-analysis.
      Following imaging (usually computed tomography [CT]/magnetic resonance angiography [MRA]), patients with ICAD may be found to have a false aneurysm affecting the distal ICA (Fig. 1), raising the question of how best these should be managed in the long term. The literature contains a number of reports detailing outcomes after open and endovascular repair of false aneurysms after ICAD, but the indications for recommending an intervention remain inconsistent.
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      • Schievink W.I.
      • Piepgras D.G.
      • McCaffrey T.V.
      • Mokri B.
      Surgical treatment of extracranial internal carotid artery dissecting aneurysms.
      • Asif K.S.
      • Lazzaro M.A.
      • Teleb M.S.
      • Fitzsimmons B.F.
      • Lynch J.
      • Zaidat O.
      Endovascular reconstruction for progressively worsening carotid artery dissection.
      • Foreman P.M.
      • Griessenauer C.J.
      • Falola M.
      • Harrigan M.R.
      Extracranial traumatic aneurysms due to blunt cerebrovascular injury.
      • Treiman G.S.
      • Treiman R.L.
      • Foran R.F.
      • Levin P.M.
      • Cohen J.L.
      • Wagner W.H.
      • et al.
      Spontaneous dissection of the internal carotid artery: a nineteen-year clinical experience.
      • Mokri B.
      • Piepgras D.G.
      • Houser O.W.
      Traumatic dissections of the extracranial internal carotid artery.
      • Tsai Y.H.
      • Wong H.F.
      • Weng H.H.
      • Chen Y.L.
      Stent-graft treatment of traumatic carotid artery dissecting pseudoaneurysm.
      • Ohta H.
      • Natarajan S.K.
      • Hauck E.F.
      • Khalessi A.A.
      • Siddiqui A.H.
      • Hopkins L.N.
      • et al.
      Endovascular stent therapy for extracranial and intracranial carotid artery dissection: single-center experience.
      Where ICAD false aneurysms have been associated with focal neurological or compressive symptoms, a more invasive approach can be justified.
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      • Mokri B.
      • Piepgras D.G.
      • Houser O.W.
      Traumatic dissections of the extracranial internal carotid artery.
      However, there is considerable uncertainty regarding the optimal management of asymptomatic false aneurysms, particularly if they do not increase in size.
      Figure thumbnail gr1
      Figure 1Three-dimensional computed tomography angiography in a 31-year-old man who suffered an acute carotid dissection with false aneurysm formation (plus a distal stenosis) in the upper internal carotid artery. This aneurysm remained unchanged in size over 3 years of imaging surveillance and was not associated with any further symptoms.
      The aim of the current systematic review was to ascertain the natural history of nonoperated false aneurysms associated with ICAD, with specific reference to aneurysm regression/progression, development of late symptoms and the need for surgical or endovascular intervention.

      Materials and Methods

      A systematic review was undertaken according to the recommendations of the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement.
      • Moher D.
      • Liberati A.
      • Tetzlaff J.
      • Altman D.
      PRISMA Group. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement.
      The PRISMA checklist with a related appendix (participants, interventions, comparisons, and outcomes) is detailed in Fig. 2 (see also Appendix in Supporting Information).
      Figure thumbnail gr2
      Figure 2Checklist with the recommendations of the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) Statement.
      • Moher D.
      • Liberati A.
      • Tetzlaff J.
      • Altman D.
      PRISMA Group. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement.
      For more information, visit www.prisma-statement.org.
      PubMed/MEDLINE, Embase, and the Cochrane databases were independently searched by two investigators (K.I.P., A.J.B.) up to 13 August 2015 in order to identify studies reporting the clinical course of nonoperated false aneurysms complicating ICAD. By use of the medical subject heading terms “carotid artery dissection AND aneurysm”, a total of 2,306 reports were identified. The abstracts of these reports were read, and full-text articles retrieved where relevant. Only English-language reports were considered. Studies reporting on the same series of patients were excluded. Single case reports were not included. The data were extracted independently by two reviewers (K.I.P and A.J.B.). Any discrepancies were resolved by a third reviewer (A.R.N.).

      Assessment of Bias

      As this was a review of small observational studies, potential sources of bias were looked into (Table 2). Selection bias was defined as missing information on baseline characteristics. Information bias was defined as absence of reporting how the aneurysm was assessed during follow-up (imaging modality/measurement protocol). Attrition bias was assumed to be present when not all participants were accounted for because they were lost to follow-up. Assessment of confounding was limited to assessment whether any factors that could influence the natural history were taken into account (such as single or dual antiplatelet therapy).
      Table 1Natural history of false aneurysms (FA) complicating internal carotid artery (ICA) dissection.
      Study (year)Number and aetiologyMean follow-up (mo)FA size increasedFA size unchangedFA size decreasedFA resolvedICA thrombosedDeferred interventionSymptoms during follow-upImaging modality for FA diagnosis
      Mokri (1990)
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      20 spontaneous640/206/208/204/202/200/200/20ANG
      Mokri (1990)
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      14 traumatic400/145/142/141/141/145/14
      Five false aneurysms were treated surgically (bypass, n = 4; ligation, n = 1), but only four were symptomatic. No data were provided on whether the aneurysm had changed in size in these patients.
      “Embolic events” (n = 4)
      Five false aneurysms were treated surgically (bypass, n = 4; ligation, n = 1), but only four were symptomatic. No data were provided on whether the aneurysm had changed in size in these patients.
      ANG
      Treiman et al. (1996)
      • Treiman G.S.
      • Treiman R.L.
      • Foran R.F.
      • Levin P.M.
      • Cohen J.L.
      • Wagner W.H.
      • et al.
      Spontaneous dissection of the internal carotid artery: a nineteen-year clinical experience.
      8 spontaneous840/86/8
      Four asymptomatic “persisting” false aneurysms were treated by resection and bypass.
      0/82/80/84/8
      Four asymptomatic “persisting” false aneurysms were treated by resection and bypass.
      0/8ANG
      Leclerc et al. (1998)
      • Leclerc X.
      • Lucas C.
      • Godefroy O.
      • Tessa H.
      • Martinat P.
      • Leys D.
      • et al.
      Helical CT for the follow-up of cervical internal carotid artery dissections.
      8 spontaneous240/84/80/84/80/80/80/8Helical CTA
      Guillon et al. (1999)
      • Guillon B.
      • Brunereau L.
      • Biousse V.
      • Djouhri H.
      • Levy C.
      • Bousser M.G.
      Long-term follow-up of aneurysms developed during extracranial internal carotid artery dissection.
      20 spontaneous370/2013/206/201/200/200/200/20MRA or ANG
      Djouhri et al. (2000)
      • Djouhri H.
      • Guillon B.
      • Brunereau L.
      • Levy C.
      • Bousson V.
      • Biousse V.
      • et al.
      MR angiography for the long-term follow-up of dissecting aneurysms of the extracranial internal carotid artery.
      26 spontaneous410/2620/264/262/260/260/260/26MRA or ANG
      Touze et al. (2001)
      • Touze E.
      • Randoux B.
      • Meary E.
      • Arquizan C.
      • Meder J.F.
      • Mas J.L.
      Aneurysmal forms of cervical artery dissection: associated factors and outcome.
      32 spontaneous370/3219/325/328/320/320/320/32DSA and/or MRA
      Benninger et al. (2007)
      • Benninger D.H.
      • Gandjour J.
      • Georgiadis D.
      • Stockli E.
      • Arnold M.
      • Baumgartner R.W.
      Benign long-term outcome of conservatively treated cervical aneurysms due to carotid dissection.
      12 spontaneous100/1212/120/120/120/120/120/12DSA and/or MRA
      Foreman et al. (2014)
      • Foreman P.M.
      • Griessenauer C.J.
      • Falola M.
      • Harrigan M.R.
      Extracranial traumatic aneurysms due to blunt cerebrovascular injury.
      26 traumatic225/26
      Two enlarging but asymptomatic false aneurysms were treated by insertion of a covered stent.
      1/2610/2610/260/262/26
      Two enlarging but asymptomatic false aneurysms were treated by insertion of a covered stent.
      0/26CTA and DSA
      Note. ANG = conventional angiography; MRA = magnetic resonance angiography; DSA = digital subtraction angiography; CTA = computed tomography angiography.
      a Five false aneurysms were treated surgically (bypass, n = 4; ligation, n = 1), but only four were symptomatic. No data were provided on whether the aneurysm had changed in size in these patients.
      b Four asymptomatic “persisting” false aneurysms were treated by resection and bypass.
      c Two enlarging but asymptomatic false aneurysms were treated by insertion of a covered stent.
      Table 2Types of bias included in the studies.
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      • Leclerc X.
      • Lucas C.
      • Godefroy O.
      • Tessa H.
      • Martinat P.
      • Leys D.
      • et al.
      Helical CT for the follow-up of cervical internal carotid artery dissections.
      • Guillon B.
      • Brunereau L.
      • Biousse V.
      • Djouhri H.
      • Levy C.
      • Bousser M.G.
      Long-term follow-up of aneurysms developed during extracranial internal carotid artery dissection.
      • Touze E.
      • Randoux B.
      • Meary E.
      • Arquizan C.
      • Meder J.F.
      • Mas J.L.
      Aneurysmal forms of cervical artery dissection: associated factors and outcome.
      • Foreman P.M.
      • Griessenauer C.J.
      • Falola M.
      • Harrigan M.R.
      Extracranial traumatic aneurysms due to blunt cerebrovascular injury.
      • Treiman G.S.
      • Treiman R.L.
      • Foran R.F.
      • Levin P.M.
      • Cohen J.L.
      • Wagner W.H.
      • et al.
      Spontaneous dissection of the internal carotid artery: a nineteen-year clinical experience.
      • Djouhri H.
      • Guillon B.
      • Brunereau L.
      • Levy C.
      • Bousson V.
      • Biousse V.
      • et al.
      MR angiography for the long-term follow-up of dissecting aneurysms of the extracranial internal carotid artery.
      • Benninger D.H.
      • Gandjour J.
      • Georgiadis D.
      • Stockli E.
      • Arnold M.
      • Baumgartner R.W.
      Benign long-term outcome of conservatively treated cervical aneurysms due to carotid dissection.
      StudySelection biasInformation biasAttrition biasConfounding
      Mokri (1990)
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      YesYesNoYes
      Treiman et al. (1996)
      • Treiman G.S.
      • Treiman R.L.
      • Foran R.F.
      • Levin P.M.
      • Cohen J.L.
      • Wagner W.H.
      • et al.
      Spontaneous dissection of the internal carotid artery: a nineteen-year clinical experience.
      YesYesYesYes
      LeClerc et al. (1998)7YesYesYesYes
      Guillon et al. (1999)
      • Guillon B.
      • Brunereau L.
      • Biousse V.
      • Djouhri H.
      • Levy C.
      • Bousser M.G.
      Long-term follow-up of aneurysms developed during extracranial internal carotid artery dissection.
      NoNoNoYes
      Djouhri et al. (2000)
      • Djouhri H.
      • Guillon B.
      • Brunereau L.
      • Levy C.
      • Bousson V.
      • Biousse V.
      • et al.
      MR angiography for the long-term follow-up of dissecting aneurysms of the extracranial internal carotid artery.
      YesYesNoYes
      Touze et al. (2001)
      • Touze E.
      • Randoux B.
      • Meary E.
      • Arquizan C.
      • Meder J.F.
      • Mas J.L.
      Aneurysmal forms of cervical artery dissection: associated factors and outcome.
      YesYesYesYes
      Benninger et al. (2007)
      • Benninger D.H.
      • Gandjour J.
      • Georgiadis D.
      • Stockli E.
      • Arnold M.
      • Baumgartner R.W.
      Benign long-term outcome of conservatively treated cervical aneurysms due to carotid dissection.
      YesYesYesYes
      Foreman et al. (2014)
      • Foreman P.M.
      • Griessenauer C.J.
      • Falola M.
      • Harrigan M.R.
      Extracranial traumatic aneurysms due to blunt cerebrovascular injury.
      NoNoNoYes

      Results

      The systematic review identified 2,306 potential papers for inclusion (Fig. 3). After duplicate reports were excluded, 2,301 abstracts were reviewed and 1,940 papers excluded. After a review of the full text in the remaining 361 studies, 353 were excluded, leaving eight studies for inclusion in the systematic review.
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      • Leclerc X.
      • Lucas C.
      • Godefroy O.
      • Tessa H.
      • Martinat P.
      • Leys D.
      • et al.
      Helical CT for the follow-up of cervical internal carotid artery dissections.
      • Guillon B.
      • Brunereau L.
      • Biousse V.
      • Djouhri H.
      • Levy C.
      • Bousser M.G.
      Long-term follow-up of aneurysms developed during extracranial internal carotid artery dissection.
      • Touze E.
      • Randoux B.
      • Meary E.
      • Arquizan C.
      • Meder J.F.
      • Mas J.L.
      Aneurysmal forms of cervical artery dissection: associated factors and outcome.
      • Foreman P.M.
      • Griessenauer C.J.
      • Falola M.
      • Harrigan M.R.
      Extracranial traumatic aneurysms due to blunt cerebrovascular injury.
      • Treiman G.S.
      • Treiman R.L.
      • Foran R.F.
      • Levin P.M.
      • Cohen J.L.
      • Wagner W.H.
      • et al.
      Spontaneous dissection of the internal carotid artery: a nineteen-year clinical experience.
      • Djouhri H.
      • Guillon B.
      • Brunereau L.
      • Levy C.
      • Bousson V.
      • Biousse V.
      • et al.
      MR angiography for the long-term follow-up of dissecting aneurysms of the extracranial internal carotid artery.
      • Benninger D.H.
      • Gandjour J.
      • Georgiadis D.
      • Stockli E.
      • Arnold M.
      • Baumgartner R.W.
      Benign long-term outcome of conservatively treated cervical aneurysms due to carotid dissection.
      Figure thumbnail gr3
      Figure 3Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) 2009 flow diagram. Note. a Of these 83 non-English-language reports, 59 were case reports, 13 were reviews, and 11 were brief commentaries/letters.
      Table 1 details clinical and surveillance outcomes in 166 patients with a nonoperated false aneurysm complicating ICAD from the eight published series.
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      • Leclerc X.
      • Lucas C.
      • Godefroy O.
      • Tessa H.
      • Martinat P.
      • Leys D.
      • et al.
      Helical CT for the follow-up of cervical internal carotid artery dissections.
      • Guillon B.
      • Brunereau L.
      • Biousse V.
      • Djouhri H.
      • Levy C.
      • Bousser M.G.
      Long-term follow-up of aneurysms developed during extracranial internal carotid artery dissection.
      • Touze E.
      • Randoux B.
      • Meary E.
      • Arquizan C.
      • Meder J.F.
      • Mas J.L.
      Aneurysmal forms of cervical artery dissection: associated factors and outcome.
      • Foreman P.M.
      • Griessenauer C.J.
      • Falola M.
      • Harrigan M.R.
      Extracranial traumatic aneurysms due to blunt cerebrovascular injury.
      • Treiman G.S.
      • Treiman R.L.
      • Foran R.F.
      • Levin P.M.
      • Cohen J.L.
      • Wagner W.H.
      • et al.
      Spontaneous dissection of the internal carotid artery: a nineteen-year clinical experience.
      • Djouhri H.
      • Guillon B.
      • Brunereau L.
      • Levy C.
      • Bousson V.
      • Biousse V.
      • et al.
      MR angiography for the long-term follow-up of dissecting aneurysms of the extracranial internal carotid artery.
      • Benninger D.H.
      • Gandjour J.
      • Georgiadis D.
      • Stockli E.
      • Arnold M.
      • Baumgartner R.W.
      Benign long-term outcome of conservatively treated cervical aneurysms due to carotid dissection.
      Forty false aneurysms (24%) followed traumatic ICAD, while 126 (76%) were classed as having occurred following spontaneous ICAD. The mean follow-up period for the 166 patients was 38.5 months (range 1 month–15 years). The demographic data, sex ratios, and/or aneurysm sizes were not specified in six of the eight studies.
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      • Leclerc X.
      • Lucas C.
      • Godefroy O.
      • Tessa H.
      • Martinat P.
      • Leys D.
      • et al.
      Helical CT for the follow-up of cervical internal carotid artery dissections.
      • Touze E.
      • Randoux B.
      • Meary E.
      • Arquizan C.
      • Meder J.F.
      • Mas J.L.
      Aneurysmal forms of cervical artery dissection: associated factors and outcome.
      • Treiman G.S.
      • Treiman R.L.
      • Foran R.F.
      • Levin P.M.
      • Cohen J.L.
      • Wagner W.H.
      • et al.
      Spontaneous dissection of the internal carotid artery: a nineteen-year clinical experience.
      • Djouhri H.
      • Guillon B.
      • Brunereau L.
      • Levy C.
      • Bousson V.
      • Biousse V.
      • et al.
      MR angiography for the long-term follow-up of dissecting aneurysms of the extracranial internal carotid artery.
      • Benninger D.H.
      • Gandjour J.
      • Georgiadis D.
      • Stockli E.
      • Arnold M.
      • Baumgartner R.W.
      Benign long-term outcome of conservatively treated cervical aneurysms due to carotid dissection.
      Overall, only five of 166 false aneurysms (3%) increased in size during follow-up. Of the remainder, 86 of 166 false aneurysms (52%) remained unchanged in size; 35 of 166 (21%) diminished in size, while 32 of 166 (19%) resolved completely. Three false aneurysms (2%) spontaneously thrombosed (along with the ICA) without causing symptoms. Accordingly, 161 false aneurysms (97%) either remained unchanged in size or regressed/resolved.
      Only four patients with an initially nonoperated false aneurysm after traumatic ICAD (2%) developed new neurological symptoms during follow-up and all were from the same publication.
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      No further clinical details were provided in these four patients, other than stating that they were “presumed to be embolic from thrombus in the residual false aneurysm” and that symptoms occurred up to 3 years after aneurysm detection. No focal neurological symptoms were reported during the course of follow-up in 126 patients with a false aneurysm after spontaneous ICAD.
      Eleven patients (7%) ultimately underwent open or endovascular intervention (Table 1), but only four were as a consequence of “late embolic symptoms” (see above).
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      • Foreman P.M.
      • Griessenauer C.J.
      • Falola M.
      • Harrigan M.R.
      Extracranial traumatic aneurysms due to blunt cerebrovascular injury.
      • Treiman G.S.
      • Treiman R.L.
      • Foran R.F.
      • Levin P.M.
      • Cohen J.L.
      • Wagner W.H.
      • et al.
      Spontaneous dissection of the internal carotid artery: a nineteen-year clinical experience.
      The indications for intervening in the remaining seven patients were aneurysm persistence (n = 5) or aneurysm expansion (n = 2). Overall, five of the 11 treated false aneurysms underwent resection and interposition bypass, while one patient underwent extracranial to intracranial bypass, three were treated by carotid ligation, and two expanding false aneurysms were treated by insertion of a covered stent. The other three expanding false aneurysms were treated conservatively and none developed recurrent symptoms.

      Discussion

      The incidence of spontaneous ICAD is about three per 100,000 population.
      • Giroud M.
      • Fayolle H.
      • Andre N.
      • Dumas R.
      • Becker F.
      • Martin D.
      • et al.
      Incidence of internal carotid artery dissection in the community of Dijon.
      Spontaneous ICAD accounts for 25% of strokes in patients aged under 45 years of age and up to 2% of ischaemic strokes overall.
      • Schievink W.I.
      Spontaneous dissection of the carotid and vertebral arteries.
      • Lee V.H.
      • Brown Jr., R.D.
      • Manderkar J.N.
      • Mokri B.
      Incidence and outcome of cervical artery dissection: a population-based study.
      • Bogousslansky J.
      • Pierre P.
      Ischemic stroke in patients under age 45.
      Although most ICADs generally follow a benign course after the initial high-risk period, 13–49% may be complicated by the development of a false aneurysm.
      • Houser O.W.
      • Mokri B.
      • Sundt Jr., T.M.
      • Baker Jr., H.L.
      • Reese D.F.
      Spontaneous cervical cephalic arterial dissection and its residuum: angiographic spectrum.
      • Mokri B.
      • Sundt Jr., T.M.
      • Houser O.W.
      • Piepgras D.G.
      Spontaneous dissection of the cervical internal carotid artery.
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      • Leclerc X.
      • Lucas C.
      • Godefroy O.
      • Tessa H.
      • Martinat P.
      • Leys D.
      • et al.
      Helical CT for the follow-up of cervical internal carotid artery dissections.
      • Guillon B.
      • Brunereau L.
      • Biousse V.
      • Djouhri H.
      • Levy C.
      • Bousser M.G.
      Long-term follow-up of aneurysms developed during extracranial internal carotid artery dissection.
      • Touze E.
      • Randoux B.
      • Meary E.
      • Arquizan C.
      • Meder J.F.
      • Mas J.L.
      Aneurysmal forms of cervical artery dissection: associated factors and outcome.
      To date, there has been no consensus as to how best these (usually asymptomatic) patients with false aneurysms should be managed. Medical treatment involves either formal anticoagulation or dual antiplatelet therapy, although there is no evidence that either is safe or preferrable.
      • Chowdhury M.
      • Sabbagh C.N.
      • Jackson D.
      • Coughlin P.A.
      • Ghost J.
      Antithrombotic treatment for acute extracranial carotid artery dissections: a meta-analysis.
      The first observation from this systematic review was that only 3% of initially nonoperated false aneurysms increased in size during a mean 38.5-month period of follow-up (range 1 month–15 years). The remaining false aneurysms (97%) either remained unchanged (52%), decreased in size (21%), or resolved completely (21%). A very small proportion (2%) thrombosed when the ICA spontaneously thrombosed.
      The second finding was that only four of 166 of aneurysms (2%) developed symptoms during follow-up. All four followed traumatic ICAD and all were from the same publication.
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      No false aneurysms that arose after spontaneous ICAD developed symptoms.
      The third finding was that only 11 patients (7%) underwent some form of invasive intervention during follow-up. Four followed the onset of symptoms, which occurred months/years after aneurysm formation and were assumed to be embolic in origin,
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      while seven asymptomatic patients underwent open/endovascular treatment of an expanding false aneurysm (n = 2) or a persisting false aneurysm (n = 5).
      Some authors have argued for a more aggressive approach to treating ICAD-related false aneurysms,
      • El-Sabrout R.
      • Cooley D.A.
      Extracranial carotid artery aneurysms: Texas Heart Institute experience.
      while others have advocated a more conservative approach.
      • Menon R.
      • Kerry S.
      • Norris J.W.
      • Markus H.S.
      Treatment of cervical artery dissection: a systematic review and meta-analysis.
      The 2014 American Heart Association/American Stroke Association Guidelines recommend an initially conservative treatment strategy in patients with ICAD,
      • Biller J.
      • Sacco R.L.
      • Albuquerque F.C.
      • Demaerschalk B.M.
      • Fayad P.
      • Long P.H.
      • et al.
      American Heart Association Stroke Council
      Cervical arterial dissections and association with cervical manipulative therapy: a statement for healthcare professionals from the American Heart Association/American Stroke Association.
      but there is no specific recommendation relating to the treatment of post-ICAD false aneurysms. The evidence from this systematic review would suggest that the natural history of post-ICAD false aneurysms is generally benign and that a policy of clinical and imaging surveillance is appropriate.
      The constituent studies in this systematic review do, however, have limitations. Firstly, owing to the relative rarity of the condition, most studies reported on <20 patients (Table 1). These relatively small case series are sensitive to bias, owing to variations in patient characteristics in the constituent studies (e.g., age, sex) and by the approach to treatment (conservative vs. prointervention). The various types of bias that were present in each study limit the scientific validity of our conclusions (Table 2). Furthermore, the imaging modality used for the follow-up varied between studies (e.g., helical CT,
      • Leclerc X.
      • Lucas C.
      • Godefroy O.
      • Tessa H.
      • Martinat P.
      • Leys D.
      • et al.
      Helical CT for the follow-up of cervical internal carotid artery dissections.
      conventional angiography,
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      MRA,
      • Guillon B.
      • Brunereau L.
      • Biousse V.
      • Djouhri H.
      • Levy C.
      • Bousser M.G.
      Long-term follow-up of aneurysms developed during extracranial internal carotid artery dissection.
      etc.). In addition, several patients were lost to follow-up.
      • Mokri B.
      Traumatic and spontaneous extracranial internal carotid artery dissections.
      • Djouhri H.
      • Guillon B.
      • Brunereau L.
      • Levy C.
      • Bousson V.
      • Biousse V.
      • et al.
      MR angiography for the long-term follow-up of dissecting aneurysms of the extracranial internal carotid artery.
      Finally, most of the studies were relatively old and therefore had no access to more sophisticated imaging strategies at the time of diagnosis and during follow-up. Secondly, there has never been a randomized controlled trial to test the relative efficacy of conservative versus interventional treatment. Thirdly, there may be other unpublished series that might otherwise have reported higher rates of stroke/transient ischaemic attack in patients with nonoperated false aneurysms after ICAD (i.e., publication bias). The fact that none of the published series on false aneurysm formation after spontaneous ICAD in Table 1 reported any recurrent symptoms during follow-up might be considered “unexpected”. The lack of accurate information regarding the fate and optimal management of such false aneurysms complicating traumatic/spontaneous ICAD calls for better reporting standards and/or an international registry for these rare clinical entities.
      In conclusion, the available evidence suggests that the vast majority of patients who develop a false aneurysm affecting the distal ICA after ICAD can be managed conservatively with antiplatelet and/or anticoagulant therapy. They can be reassured that the vast majority of false aneurysms will either reduce in size, resolve completely, or remain unchanged, and that it is highly unlikely that they will develop recurrent symptoms during follow-up. An annual follow-up using MRA or CT angiography is probably appropriate to ensure that the false aneurysm has not increased in size. Intervention should be reserved for the very small minority of patients who develop symptoms during follow-up and a range of open and endovascular interventions are available should they be required.

      Conflict of Interest

      None.

      Funding

      None.

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      Linked Article

      • Re. “Fate of the Distal False Aneurysms Complicating Internal Carotid Artery Dissection: Systematic Review”
        European Journal of Vascular and Endovascular SurgeryVol. 53Issue 2
        • Preview
          Extracranial carotid artery aneurysms (ECAA) are an uncommon condition and the natural course remains unknown.1 Among various etiological factors, dissection seems to be most prominent.2 Paraskevas et al. reviewed eight studies on 166 patients with distal false carotid aneurysms and found that over 50% of aneurysms remained unchanged while only four patients underwent late surgery.3 The authors concluded that conservative management with serial surveillance is the optimal approach for false aneurysms.
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