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 Table of Contents  
CASE REPORT
Year : 2021  |  Volume : 9  |  Issue : 1  |  Page : 29-31

Incidental unruptured aneurysm of the distal M2 segment: Case report and review of literature


Department of Neurosurgery, Apollo Hospitals, Chennai, Tamil Nadu, India

Date of Submission21-May-2021
Date of Decision14-Jun-2021
Date of Acceptance18-Jul-2021
Date of Web Publication27-Aug-2021

Correspondence Address:
Dr. K Giridharan
Department of Neurosurgery, Apollo Hospitals, Chennai, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jcvs.jcvs_10_21

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  Abstract 


Aneurysms of the Middle cerebral artery (MCA) are more common at the bifurcation. Distal MCA aneurysm in M2, M3 and M4 segments are rare. Here, we discuss an incidental distal M2 segment aneurysm and its management along with a brief literature review. Fifty-one-year-old male, presented to us with a history of the giddiness of 1-week duration. During the evaluation for giddiness, his computed tomography (CT) brain plain showed a small well-defined hyperdense rounded lesion in the left Sylvian fissure. CT angiogram was done and it showed a saccular aneurysm measuring 7.7 mm × 7.3 mm and had a narrow neck of 1.5 mm arising from the distal M2 segment of MCA. The aneurysm was directed superiorly in the distal MCA. Digital subtraction angiogram showed a 6.4 mm × 6.9 mm distal M2 segment bilobed aneurysm with a neck of 3.8 mm and projecting superiorly. Surgical clipping of the aneurysm was done. Perioperative period was uneventful and the patient is doing well at 3 months follow-up. Review of the literature showed that the incidence of distal MCA aneurysm was low. Intra-operative CT angiogram, neuro-navigation, indocyanine green video angiography (ICGV) are some of the useful tools in improving outcomes in surgical clipping of these aneurysms. Distal MCA aneurysms are less frequently encountered. Surgical clipping is the treatment of choice in these cases. Challenge arises in localising these aneurysms and adjuncts such as intraoperative CT angiogram, neuro-navigation, ICGV can be useful to overcome that challenge.

Keywords: Aneurysm clipping, distal middle cerebral artery aneurysm, M2 segment aneurysm, management of aneurysm, middle cerebral artery aneurysm


How to cite this article:
Giridharan K, Nathan S, Patil S, Mangaleswaran B. Incidental unruptured aneurysm of the distal M2 segment: Case report and review of literature. J Cerebrovasc Sci 2021;9:29-31

How to cite this URL:
Giridharan K, Nathan S, Patil S, Mangaleswaran B. Incidental unruptured aneurysm of the distal M2 segment: Case report and review of literature. J Cerebrovasc Sci [serial online] 2021 [cited 2021 Dec 1];9:29-31. Available from: http://www.jcvs.com/text.asp?2021/9/1/29/324806




  Introduction Top


Middle cerebral artery (MCA) aneurysms are more common at the bifurcation.[1] Distal MCA aneurysm including the M2, M3 and M4 segments are rare. The incidence according to our literature search was about 0.70%–9.4% among MCA aneurysms [Table 1]. Here, we present a case of un-ruptured saccular aneurysm of the left distal M2 segment with its presentation, management and a brief review of literature.
Table 1: Incidence of distal middle cerebral artery aneurysm in literature

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  Case Report Top


Fifty-one-year-old male, a known case of coronary artery disease– status post percutaneous transluminal coronary angioplasty and stenting with moderate left ventricular dysfunction, on dual antiplatelets, presented to us with a history of giddiness of 1-week duration. He was evaluated by the ENT team and diagnosed to have benign paroxysmal positional vertigo. During the evaluation for giddiness, his computed tomography (CT) brain plain showed a small well-defined hyperdense rounded lesion in the left Sylvian fissure arising from the M2 segment of the left MCA [Figure 1]. CT angiogram was done and it showed a saccular aneurysm measuring 7.7 mm × 7.3 mm with a narrow neck of 1.5 mm arising from the distal M2 segment of MCA. The aneurysm was directed superiorly in the distal MCA [Figure 1]. There was no history of headache, features of complex partial seizures or limb weakness. He had a history of progressive, painless diminished vision in the left eye due to cataract for the past 9 months. Digital subtraction angiogram of the cerebral vessels was proceeded with and showed a bilobed aneurysm in the left MCA – distal M2 segment branch, pointing superiorly. It was incorporating a branch which appeared dysplastic. The aneurysm measured 6.4 mm × 6.9 mm with a neck of 3.8 mm [Figure 2]. Patients and attenders were explained about the image findings and given the options of surgical clipping and endovascular coil embolization, including the pros and cons of each. They agreed to proceed with Surgical clipping of the aneurysm. Antiplatelets were discontinued from 1 week before surgery.
Figure 1: Non contrast computed tomography and computed tomography angiogram of Brain. Non contrast Computed tomography showing aneurysm in the left Sylvian fissure as seen in Axial (a), coronal (b) and sagittal (c) sections. Computed tomography angiogram showing aneurysm in the left Sylvian fissure as seen in Axial (d), coronal (e) and sagittal (f) sections

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Figure 2: Angiographic images of the aneurysm. Computed tomography angiography reconstruction image (a), Digital subtraction angiogram lateral view (b) and Antero-posterior view (c). Three-dimensional reconstruction of the aneurysm from digital subtraction angiogram (d and e)

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Intra operative findings

Through standard left pterional craniotomy, Sylvian dissection was done. MCA M1 segment including the bifurcation, M2 segments and their branches defined. The saccular aneurysm in the distal M2 segment was identified with multiple surface blebs [Figure 3]. A branch was seen to arise at just about the neck of the aneurysm. Aneurysm was clipped using at 6.5 mm curved clip, carefully including the blebs and avoiding the branch arising from the neck [Figure 3].
Figure 3: Intraoperative pictures of the aneurysm and its clipping. Aneurysm in distal M2 segment with multiple blebs (a). Application of clip with proximal control in place. Blebs included within the clip while sparing the branching vessel (b). Post application of clip with proximal control in place (c). After removal of proximal control (d)

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Post-operative period was uneventful. The patient had no neurological deficit at 1 month follow-up.


  Discussion Top


Among the cerebral vessels, the MCA is the largest and most complex.[1] Micro surgically it is divided into four segments: Sphenoidal (M1), insular (M2), opercular (M3), cortical (M4).[1],[8] Some authors describe a Terminal segment (M5) also.[1],[8] The MCA is the most common site of saccular aneurysms.[1] Among the various classifications, the most accepted one divides it into four groups: Proximal, bifurcation, distal and cortical aneurysms.[8] Most of the MCA aneurysms occur at the bifurcation, while the distal and cortical aneurysms are very rare.[9] Most commonly, the latter ones manifest clinically with rupture and intracranial haemorrhage.[9]

Aneurysms of distal MCA are a rarely seen condition, constituting 0.47% of all aneurysms and 1.1%–5% of MCA aneurysms.[3],[5]

The incidence of Distal MCA aneurysm in some of the available literature is given in [Table 1].

Gibo et al.,[1] described that to locate MCA aneurysms, the distal vessel was classified into four segments M2 (insular segment), M2–M3 junction, M3 (opercular segment) and M4 (cortical segment). Most commonly the MCA aneurysms occur at the division of the main trunk (M1–M2 junction) due to hemodynamic stress and/or congenital factors.

These distal MCA aneurysms often present with rupture and intracerebral bleed.[9] More commonly they are associated with trauma.[9] Treatment of these aneurysm is a challenge in view of difficulty in locating the aneurysm during surgery and the lack of collaterals.[10] An inaccurate localisation of aneurysm may lead to larger craniotomies and unnecessary arachnoid and pial dissections which may result in permanent neurological injuries.[10] Surgical clipping and obliteration of the aneurysm is the most preferred treatment option. The intraoperative CT angiography integrated with a navigation platform is the recommended standard of care.[9] In the absence of which, a conventional neuronavigation system guidance is recommended. The use of indocyanine green video angiography (ICGV) is recommended if available, before and after clipping of aneurysm. It helps in ascertaining the perforators and in defining the neck before application of the clip and in confirming the flow in distal vessels and perforators after clipping.[11]


  Conclusion Top


Distal MCA segment (M2, M3 and M4) aneurysms are rare in occurrence. Proper pre-operative workup with CT angiogram, cerebral digital subtraction angiogram and planning of the procedure is recommended. Intra-operative use of Neuronavigation, ICGV, intra-operative CT angiogram, if available will help in improving the accuracy of localization of the aneurysm. Surgical clipping of the aneurysm is the treatment of choice.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Gibo H, Carver CC, Rhoton AL, Lenkey C, Mitchell RJ. Microsurgical anatomy of the middle cerebral artery. Jeurosurg 1981;54:151-69.  Back to cited text no. 1
    
2.
Yasargil MG. Microneurosurgery II: Clinical considerations, surgery of the intracranial aneursyms and results. Vol. 2; Stuttgart: Georg Thieme Verlag; 1984. p. 124-64.  Back to cited text no. 2
    
3.
Rinne J, Hernesniemi J, Niskanen M, Vapalahti M. Analysis of 561 patients with 690 middle cerebral artery aneurysms: Anatomic and clinical features as correlated to management outcome. Neurosurgery 1996;38:2-11.  Back to cited text no. 3
    
4.
Baltacioğlu F, Cekirge S, Saatci I, Oztürk H, Arat A, Pamir N, et al. Distal middle cerebral artery aneurysms. Endovascular treatment results with literature review. Interv Neuroradiol 2002;8:399-407.  Back to cited text no. 4
    
5.
Dashti R, Hernesniemi J, Niemelä M, Rinne J, Lehecka M, Shen H, et al. Microneurosurgical management of distal middle cerebral artery aneurysms. Surg Neurol 2007;67:553-63.  Back to cited text no. 5
    
6.
Narisawa A, Kon H, Kawaguchi T, Takazawa H, Morita T, Sonobe S, et al. Characteristics of distal middle cerebral artery aneurysm. Nosotchu 2012;34:304-9.  Back to cited text no. 6
    
7.
Tsutsumi K, Horiuchi T, Nagm A, Toba Y, Hongo K. Clinical characteristics of ruptured distal middle cerebral artery aneurysms: review of the literature. Journal of Clinical Neuroscience. 2017;40:14-7.  Back to cited text no. 7
    
8.
Elsharkawy A, Lehečka M, Niemelä M, Billon-Grand R, Lehto H, Kivisaari R, et al. New, more accurate classification of middle cerebral artery aneurysms: Computed tomography angiographic study of 1009 consecutive cases with 1309 middle cerebral artery aneurysms. Neurosurgery 2013;73:94-102.  Back to cited text no. 8
    
9.
Ricci A, Di Vitantonio H, De Paulis D, Del Maestro M, Raysi SD, Murrone D, et al. Cortical aneurysms of the middle cerebral artery: A review of the literature. Surg Neurol Int 2017;8:117.  Back to cited text no. 9
    
10.
Raza SM, Papadimitriou K, Gandhi D, Radvany M, Olivi A, Huang J. Intra-arterial intraoperative computed tomography angiography guided navigation: A new technique for localization of vascular pathology. Neurosurgery 2012;71 Suppl. 2:ons240-52.  Back to cited text no. 10
    
11.
Raabe A, Beck J, Gerlach R, Zimmermann M, Seifert V, Macdonald RL, et al. Near-infrared indocyanine green video angiography: A new method for intraoperative assessment of vascular flow. Neurosurgery 2003;52:132-9.  Back to cited text no. 11
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

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