|Year : 2020 | Volume
| Issue : 1 | Page : 19-23
Surgery for anterior communicating artery aneurysms: Lessons learnt
Jaspreet Singh Dil1, Sumeet Narang1, Harpreet Kaur2, A Raja1
1 National Neurosciences Mission, Adarsha Super-specialty Hospital, Manipal-Udupi, Karnataka, India
2 Department of Anaesthesiology, SMS Medical College, Jaipur, Rajasthan, India
|Date of Submission||10-Aug-2020|
|Date of Acceptance||03-Sep-2020|
|Date of Web Publication||1-Oct-2020|
Dr. Sumeet Narang
National Neurosciences Mission, Adarsha Super-specialty Hospital, Manipal-Udupi, Karnataka
Source of Support: None, Conflict of Interest: None
Background: Anterior communicating artery (ACoA) aneurysms are one of the most common cerebral aneurysms encountered by neurovascular surgeons. They are surgically complex and sensitive and the scope for dialogue and exchange towards development are never over rated.
Aims and objectives: The authors seek to discuss and emphasize on key lessons learnt from the observations from ACoA aneurysms treated by micro-vascular clipping.
Materials and Methods: Hospital based retrospective observational study of 237 cases of ACoA aneurysms admitted to the study hospital and treated by micro-vascular clipping.
Conclusion: The lessons learnt are broadly under the headings: exposure, intracranial pressure, gyrus rectus resection, vascular anatomy, perforator preservation, temporary clipping, damage control, lamina terminalis fenestration, team play, cognitive and morbidity assessment, and timing of surgery.
Keywords: Aneurysm, anterior communicating artery, surgery
|How to cite this article:|
Dil JS, Narang S, Kaur H, Raja A. Surgery for anterior communicating artery aneurysms: Lessons learnt. J Cerebrovasc Sci 2020;8:19-23
|How to cite this URL:|
Dil JS, Narang S, Kaur H, Raja A. Surgery for anterior communicating artery aneurysms: Lessons learnt. J Cerebrovasc Sci [serial online] 2020 [cited 2020 Nov 27];8:19-23. Available from: http://www.jcvs.com/text.asp?2020/8/1/19/296940
| Introduction|| |
Anterior communicating artery (ACoA) complex is the most frequent site of intracranial aneurysms in most reported series. They are surgically the most complex aneurysms of the anterior circulation due to the angio-architecture and flow dynamics of the region, frequent anatomical variations, deep location and existing danger of harm to the surrounding structures, which could result in serious neurologic deficits. The presented article is a synopsis of key lessons learnt in retrospection from microvascular clipping of ACoA aneurysms in 237 patients diagnosed with the condition.
The objective was to discuss and emphasise on key lessons learnt from the observed advantages and disadvantages of various aspects of the surgery for ACoA aneurysms.
| Methods|| |
This was a hospital-based, retrospective, observational study of 237 patients admitted to the National Neurosciences Mission, Adarsha Super-Specialty Hospital (Manipal-Udupi, Karnataka, India) with ACoA aneurysms as diagnosed clinically and radiologically through computed tomography and digital subtraction angiography, managed surgically by microvascular aneurysm clipping.
| Results|| |
Based on the authors' personal experiences with 571 cerebral aneurysms that were operated upon, 41.5% of all cases that is, 237 cases, were ACoA aneurysms. Of those 237, 61.1% were between the ages of 40 and 60 years; 56.5% were males and 43.5% were females. Most patients that is, 54.4% presented with World Federation of Neurological Surgeons Grade 1 subarachnoid haemorrhage (SAH) and 55.2% were found to have a Type III circulation pattern.
The lessons learnt are broadly on the intraoperative steps necessary for good exposure and conducive conditions in the operative field before tackling the aneurysm and the manoeuvres and mindset essential in overcoming the key mission of successfully and effectively treating the aneurysm, while also taking due consideration of the results postoperatively, which affect the surgeon as well as the patient.,
| Discussion|| |
There are important take-home messages to be assimilated from the surgeons' seat of operation. There are significant advantages to some aspects of the surgical strategy and the operative steps, which, though known, are sometimes not implemented, and must be reiterated and routinely practiced for a favourable surgical outcome; while at the same time, there are certain other areas which receive more attention than indicated.
This is of utmost importance for good visual and instrument access in the confined space where cerebrovascular surgeons enter. Using a drill or a bone nibbler to excise the lateral wing of the sphenoid bone greatly aids in this aspect. By facilitating exposure, this step also reduces the amount of retraction needed while operating, which by default means reduction of the avoidable iatrogenic trauma to the brain that occurs on retraction [Figure 1].
The intracranial tension (ICT) is another obvious parameter that affects the route to the aneurysm and the space and conditions of the operative field. The degree of ICT also directly affects the incidence of shunt-dependent hydrocephalus postoperatively. Obtaining laxity of the brain, as far as possible, lowers intraoperative risks that arise due to high ICT. ICT can be optimised by performing a cisternostomy [Figure 2] and [Figure 3]. Opening the cisterns allows the cerebrospinal fluid to be drained and within a short amount of time, turns the brain lax. An alternative is to have a ventricular or a lumbar drain in situ during surgery. Planning for the same varies in accordance with the patient's condition, but where scans reveal dilatation of the ventricles or oedema, and where the surgeon anticipates a high ICT, the presence of the drain is a simple solution which can make a difference.
Gyrus rectus resection
Our experiences have led us to believe that resection of the gyrus does not produce long-term disabilities to the patient and, in fact, is a very useful step, especially in anteriorly and inferiorly directed aneurysms, as it prevents landing on the fundus first. It provides us with those valuable few millimetres that aids the dissection of the neck of the aneurysm and helps to easily visualise the opposite A2. This step also reduces the need for a more forceful retraction which should be avoided where possible [Figure 4].
On occasions when surgeons have self-imposed time constraints for whatever reason, we think we have reached as far as we need to once the aneurysm is identified. This, however, is a short cut with possible disastrous effects. One very important lesson for a cerebrovascular surgeon approaching an aneurysm is that one must see more of the vascular system than one needs to. Visualisation of the aneurysm alone is not adequate, and one must also visualise at least the A1 segment proximal to the ACoA origin, the A2 segment distal to the ACoA origin and also the recurrent artery of Heubner and the perforating branches of ACoA before proceeding with the clipping.,, Taking the time to provide oneself with this arterial map facilitates navigation by providing a wider field [Figure 5] and [Figure 6].
The aim of the surgery is total occlusion of the aneurysm while preserving the perforators.,, The severance of the hypothalamic perforators, which causes devastating neurological deficits, is one amongst the most serious risks that make ACoA aneurysms surgically sensitive. We believe that the hypothalamicperforatorsarethethreadstoabetterlife. There can be no compromise and no margin for error in dealing with these vessels and it is absolutely imperative to save them. This statement again highlights the necessity of adequate identification of the vascular anatomy.
It is at the time of clipping of the neck of the aneurysm that utmost caution is to be implemented. The most tremendous risk visible to none but to the surgeon, is the rupture of the sac. This risk can be averted by the application of a temporary clip, proximal to the neck, on either one or both sides, depending on the type of circulation in the Circle of Willis, before the application of the final clip. Occluding the proximal vessel with a proximal clip reduces the flow to the aneurysm and makes the dissection of the neck easier and safer, and can be reapplied till the surgeon is more than satisfied with the situation [Figure 7]. We recommend the intermittent application of temporary clips [Figure 8] for 2–3 min followed by a release for 2–3 min before re-applying if required, to maintain the cerebral perfusion during those intervals. Once the surgeon is assured that the dissection is adequate, the final clip can be applied with more confidence than anxiety.
Intraoperative rupture of the aneurysm sac is a perpetual risk. In the unwanted irreversible event where a rupture occurs despite one's best efforts to prevent it, panic worsens the calamity. It is advised to proceed slowly, rather than in a hurry. The best solution is again to employ a temporary clip to control the bleeding. The temporary clip provides the surgeon with more time to evaluate the situation and implement a remedy.
Lamina terminalis fenestration
A lot of importance has been given to this step in the surgery for aneurysms, to prevent post-operative shunt-dependent hydrocephalus. However, the factors that could predispose to post-operative hydrocephalus are actually at play even prior to the surgery, such as the grade of the aneurysm itself. Although some surgeons routinely open the lamina terminalis in aneurysm surgery, our studies indicate that there is no significant difference in the incidence of post-operative hydrocephalus in cases where this step was not performed, which is in line with the findings observed by other studies, that opening of the lamina terminalis did not result in its functional patency.
No amount of skill or experience makes surgery a one-man show. Coordination and cooperation amongst all members of the involved team is vital in contributing to the success of the procedure, from before it starts to after it ends. Thorough planning and communication with the neuro-anaesthetist is imperative. The anaesthesia team must be aware of the surgeon's strategy and anticipated risks, such as the plan to use temporary clips, which affects the haemodynamic status, and to be able to execute their functions in tune with the events on the table, for example, in the administration of propofol for cerebroprotection.
Cognitive and morbidity assessment
Despite outstanding progress and results in cerebrovascular surgery in India, perhaps, one drawback lies in the lack of evidence of the condition and quality of life of the numerous patients surgically treated. Several factors contribute to the difficulty in objectively carrying out such analyses, but it is only by facing those numbers that we as neurosurgeons can keep our feet on the ground and strive for continuous development. Efforts need to be made to follow-up with patients on a long term before we can consider their management complete.
Lastly, the timingofthesurgery,,, is a subject of little debate in the management of a patient presenting with an SAH, as studies have shown that surgery is required at the earliest practically possible to prevent a life-threatening rebleed. In agreement with 'the International Cooperative Study on the Timing of Aneurysm Surgery', we have experienced that overall outcome is better with early surgery, which yields a lower mortality (Kassell and Hernesniemi). The post-operative risk following early surgery is equivalent to the risk of rebleeding and vasospasm in patients who undergo delayed surgery. Surgical outcome might only appear to be better in patients operated later, possibly because they have survived the condition long enough to cross the threshold of suffering a rebleed, creating favourable surgical conditions, but with worse morbidity in the long run. Although the timing of the presentation is not always in the surgeons' control, it must be remembered that the decision to intervene promptly is an integral part of the strategy without which none of the above lessons would bear significance.
| Conclusion|| |
Neurovascular surgery has been an ever-evolving field from the era of the air-ventriculogram to the ready images on a magnetic resonance imaging film. Just as much has been learnt over the years through the documented experiences of surgeons, more must be shared for further progress in the field.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]