Elsevier

Surgical Neurology

Volume 67, Issue 6, June 2007, Pages 553-563
Surgical Neurology

Aneurysm–Rainbow Team/Helsinki
Microneurosurgical management of distal middle cerebral artery aneurysms

https://doi.org/10.1016/j.surneu.2007.03.023Get rights and content

Abstract

Background

Distal middle cerebral artery aneurysms originate from branches of MCA distal to its main bifurcation or the peripheral branches. Distal middle cerebral artery aneurysms are the least frequently seen among the middle cerebral artery aneurysms. The purpose of this article is to review the practical anatomy, preoperative planning, and avoidance of complications in the microsurgical dissection and clipping of MdistAs.

Methods

This review, and the whole series on intracranial aneurysms, are mainly based on the personal microneurosurgical experience of the senior author (JH) in 2 Finnish centers (Helsinki and Kuopio), which serve without patient selection the catchment area in Southern and Eastern Finland.

Results

These 2 centers have treated more than 10 000 aneurysm patients since 1951. In the Kuopio Cerebral Aneurysm Database of 3005 patients with 4253 aneurysms, 69 patients carrying altogether 78 MdistAs formed 5% of all MCA aneurysms. Among the 18 patients with ruptured MdistAs (23%), an ICH occurred in 9 (50%).

Conclusions

Distal middle cerebral artery aneurysms are rare. The microneurosurgical treatment of MdistAs is challenging. They are often difficult to localize during the operation, and lack of collateral circulation makes their occlusion more demanding. High rate of ICH and high tendency of rebleeding urge acute or emergency surgery in most of ruptured cases. Microneurosurgical clipping is the most effective treatment of MdistAs.

Introduction

Middle cerebral artery aneurysms can be classified into proximal, bifurcation, or distal type (Table 1). The proximal MCA aneurysms or M1As are located in the main trunk (M1), between the bifurcation of the internal carotid artery (ICA) and the main bifurcation of MCA [9]. The MbifAs are located in the main bifurcation of MCA [10]. The MdistAs, originating from branches of MCA distal to the main bifurcation or the peripheral branches, are the focus of the present article.

Distal middle cerebral artery aneurysms are the least frequent of MCA aneurysms [18], [35], [36], [43], [56]. Microneurosurgical treatment of MdistAs is demanding. It is difficult to localize them, the small ones in particular, because they lie deep in the sylvian cistern, among the distal branches of the MCA. Intraoperative navigation may be further complicated by the presence of SAH and ICH. Furthermore, they can be mycotic, inflammatory, or dissecting [29], [39], [43]. The lack of collateral circulation makes occlusion more challenging, necessitating bypass and revascularization techniques [27], [35], [36]. Since the first definition by Poppen [30] in 1951, there are only few reports on management of MdistAs [18], [29], [35], [36], [56].

The purpose is to review the practical anatomy, preoperative planning, and avoidance of complications in the microsurgical dissection and clipping of MdistAs. This review, and the whole series on intracranial aneurysms, is intended for the neurosurgeons who are subspecializing in neurovascular surgery.

This review is mainly based on the personal microneurosurgical experience of the senior author (JH) in 2 Finnish centers (Helsinki and Kuopio), which serve, without selection, the catchment area in the southern and eastern Finland. These 2 centers have treated more than 10 000 patients with aneurysm since 1951.

The data presented in our series of articles represent 3005 consecutive patients harboring 4253 intracranial aneurysms from the Kuopio Cerebral Aneurysm Database (1977-2005). The aim is to present a consecutive, nonselected, population-based series of intracranial aneurysms without any selection bias. This database is not reflective of the personal series of the senior author (JH) alone.

Section snippets

Occurrence of MdistAs

Distal middle cerebral artery aneurysms are the least frequent of the MCA aneurysms reported to form 1.1% to 5% of them [18], [35], [36], [43], [56]. Four MdistAs form 2% of the series reported by Yaşargil [56]. In the largest series reported to date, Horiuchi et al [18] reported 9 MdistAs. Table 2, Table 3, Table 4, Table 5present clinical data of patients with MdistA in a consecutive and population-based series of 3005 patients with 4253 intracranial aneurysms from 1977 to 2005 in the Kuopio

Microsurgical anatomical considerations of MdistAs

Distal middle cerebral artery aneurysms originate from the M2s or more distal branches of MCA. Distal middle cerebral artery aneurysms are located in the lateral and distal part of the sylvian fissure, between the frontal and temporal lobes, where diverse vascular anatomy may affect the outcome of surgery. The sylvian fissure varies in shape and volume, and previous SAHs may toughen the arachnoid in and on the fissure [8], [55]. The venous anatomy of the sylvian fissure is complex and varies

Imaging of MdistAs

Digital subtraction angiography is still the present criterion standard in many centers. Multislice helical CTA is the primary modality in our centers for several reasons: noninvasive and quick imaging, comparable sensitivity and specificity to DSA in aneurysms larger than 2 mm [20], [46], [53], [54], disclosure of calcifications in the walls of arteries and aneurysm, and quick reconstruction of 3-dimensional (3D) images (Fig. 3).

For intraoperative navigation toward MdistAs, 3D CTA or DSA

Microsurgical strategy with MdistAs

We divide MdistAs into (a) aneurysms on M2 or M2-M3 junction and (b) those distal to M2-M3 junction. In the proximity of the main MCA bifurcation, the approach suitable for the by far more prevalent MbifAs will do [10]. To expose more MdistAs, the approach must be more occipital over the sylvian fissure.

The more distal MdistAs are, the more difficult it is to locate them in the sylvian cistern and sulci, among the distal branches of the MCA, and, in particular, in the presence of SAH or ICH.

General principles

The sylvian fissure is opened appropriately over the site of the aneurysm. We prefer to identify and follow M2s or M3s in proximal to distal direction. After finding the aneurysm, the rest of the dissection and subsequent clipping are often straightforward. With the help of temporary clipping, the base of the aneurysm is dissected free, and usually, one microclip is placed on the base. It may not be advisable to dissect the dome completely before applying a pilot clip. The parent artery and the

Associated aneurysms

Distal middle cerebral artery aneurysms are particularly often associated with other aneurysms. At least one additional aneurysm was found in 51 (74%) of the 69 patients with MdistA and in 10 (56%) of the 18 patients with ruptured MdistA (Table 4). Our strategy is to clip all aneurysms that can be exposed through the same craniotomy (see video 1). This may not be advisable if the clipping of the ruptured aneurysm is difficult or the brain is swollen due to acute SAH [34].

Giant MdistAs

Distal middle cerebral artery aneurysms that occasionally grow large or giant though the hemodynamic stress are seen less than in M1As and MbifAs. In the series of 1704 MCA aneurysms (Table 3), 5 (6%) of the 78 MdistAs were large or giant (15 mm or more) as compared with 16 (7%) of the 241 M1As [9] and 207 (15%) of the 1385 MbifAs [10]. Large size further complicates clipping in terms of preserving the parent artery.

Fusiform, dissecting, and mycotic MdistAs

Fusiform, dissecting, and mycotic aneurysms are longitudinal dilations of the cerebral arteries, in sharp contrast to saccular aneurysms of the arterial forks. We prefer exosurgery over endosurgery when there is SAH or, in particular, large ICH. In some fusiform aneurysms, it may be possible to find the so-called beer belly, which is tangentially clipped with a small straight or curved clip under temporary occlusion of the parent artery. In distal aneurysms with retrograde flow, it is often

Bypass operations and arteriotomies

End-to-side or end-to-end STA-MCA bypass should be considered, particularly in proximally located MdistAs, when the exclusion of the aneurysm neck from the parent and branching arteries cannot be performed [18], [29], [39], [40].

Acknowledgments

We thank Mr Ville Kärpijoki for excellent technical assistance.

References (57)

  • J. Bailes et al.

    Management morbidity and mortality of poor-grade aneurysm patients

    J Neurosurg

    (1990)
  • H. Batjer et al.

    Emergent aneurysm surgery without cerebral angiography for the comatose patient

    Neurosurgery

    (1991)
  • L. Brandt et al.

    Ruptured middle cerebral artery aneurysm with intracerebral hemorrhage in younger patients appearing moribund: emergency operation?

    Neurosurgery

    (1987)
  • J. Chun et al.

    Current multimodality management of infectious intracranial aneurysms

    Neurosurgery

    (2001)
  • D. Chyatte et al.

    Nuances of middle cerebral artery aneurysm microsurgery

    Neurosurgery

    (2001)
  • A. Day et al.

    Spontaneous fusiform middle cerebral artery aneurysms: characteristics and a proposed mechanism of formation

    J Neurosurg

    (2003)
  • C.G. Drake et al.

    Surgery of vertebrobasilar aneurysms

    (1996)
  • J. Frösen et al.

    Contribution of mural and bone marrow–derived neointimal cells to thrombus organization and wall remodeling in a microsurgical murine saccular aneurysm model

    Neurosurgery

    (2006)
  • J. Frösen et al.

    Remodeling of saccular cerebral artery aneurysm wall is associated with rupture: histological analysis of 24 unruptured and 42 ruptured cases

    Stroke

    (2004)
  • H. Gibo et al.

    Microsurgical anatomy of the middle cerebral artery

    J Neurosurg

    (1981)
  • O. Heiskanen et al.

    Acute surgery for intracerebral haematomas caused by rupture of an intracranial arterial aneurysm. A prospective randomized study

    Acta Neurochir (Wien)

    (1988)
  • J. Hernesniemi et al.

    Lateral supraorbital approach as an alternative to the classical pterional approach

    Acta Neurochir (Wien)

    (2005)
  • T. Horiuchi et al.

    Ruptured distal middle cerebral artery aneurysm

    J Neurosurg

    (2004)
  • International Study of Unruptured Intracranial Aneurysms Investigators

    Unruptured intracranial aneurysms—risk of rupture and risks of surgical intervention. International Study of Unruptured Intracranial Aneurysms Investigators

    N Engl J Med

    (1998)
  • M. Kangasniemi et al.

    Detection of intracranial aneurysms with two-dimensional and three-dimensional multislice helical computed tomographic angiography

    Neurosurgery

    (2004)
  • K. Kazumata et al.

    Operative anatomy and classification of the sylvian veins for the distal transsylvian approach

    Neurol Med Chir

    (2003)
  • I. Papo et al.

    Intracerebral haematomas from aneurysm rupture: their clinical significance

    Acta Neurochir (Wien)

    (1987)
  • E. Pasztor et al.

    The surgery of middle cerebral artery aneurysms

    Acta Neurochir (Wien)

    (1986)
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