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|NI FEATURE: THE EDITORIAL DEBATE-- PROS AND CONS
|Year : 2016 | Volume
| Issue : 6 | Page : 1145-1146
Surgery for distal anterior cerebral artery aneurysm
B Ravi Mohan Rao
Department of Neurosurgery, Apollo Hospitals, Seshadripuram, Bangalore, Karnataka, India
|Date of Web Publication||11-Nov-2016|
B Ravi Mohan Rao
Department of Neurosurgery, Apollo Hospitals, Seshadripuram, Bangalore, Karnataka
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Rao B R. Surgery for distal anterior cerebral artery aneurysm. Neurol India 2016;64:1145-6
Distal anterior cerebral artery (DACA) aneurysms account for 6% of all intracranial aneurysms. The difficulties in surgical clipping of these aneurysms are well documented and include the narrow operative corridor between the falx cerebri and medial frontal lobe, lack of a large cistern due to which it may be difficult to release adequate cerebrospinal fluid (CSF) to relax the brain, and the lack of definite landmarks to follow for reaching the aneurysm and for achieving an early proximal control. Neuronavigation is definitely a tool that helps in planning the craniotomy and the appropriate corridor to follow to achieve an early proximal control. As the aneurysm is located on the corpus callosum (A3 aneurysms), brain shift will not introduce inaccuracies. In addition, major release of CSF usually does not occur during surgery unless the ventricle is tapped to obtain brain relaxation. Intraoperative indocyanine green (ICG) angiography using a 800 nm filter or fluorescein sodium angiography using a 560 nm filter is invaluable in confirming the absence of residual aneurysm after clipping. As this is a retrospective study spanning 25 years, intraoperative video angiography could not have been used for this purpose; however, postoperative digital subtraction angiogram (DSA)/computed tomographic (CT) angiography could have given an objective evidence of satisfactory clipping. This study also represents the experience of multiple neurosurgeons and hence may reflect their biases in approaching the ruptured DACA aneurysm. This study being retrospective also suffers from having an inadequate follow up. The publication by Dr. Juha Hernesniemi gives an idea of a single surgeon's experience in treating DACA aneurysms over several decades along with a 100% follow-up of all their patients with respect to the the long-term outcome. A total of 517 patients with DACA aneurysms were evaluated at Helsinki and Kuopio between 1936 and 2007. The treatment results were analyzed in 427 patients treated between 1980 and 2005 since both CT scans and microsurgery were used in all these patients. With a median follow-up of 10 years, 280 patients with ruptured DACA aneurysms underwent evaluation of long-term outcome after treatment. They found that, among other things, DACA aneurysms were smaller (median: 6 mm versus 8 mm) and presented more often with an intracerebral hematoma (53% versus 26%) than ruptured aneurysms in general, findings which are mirrored in this study. Microsurgical treatment showed similar complication rates (treatment morbidity 15%; treatment mortality 0.4%) as observed in other ruptured aneurysms. At 1 year after the subarachnoid hemorrhage (SAH), DACA aneurysms had equally favorable outcome (Glasgow Outcome Scale (GOS) score ≥4) as other ruptured aneurysms (74% versus 69%), however, their mortality was lower (13% versus 24%). Factors predicting an unfavorable outcome for ruptured DACA aneurysms were advanced age, Hunt and Hess grade ≥3, rebleeding before treatment, presence of an intracerebral hematoma (ICH) or intraventricular hemorrhage, and existence of associated severe preoperative hydrocephalus. The cumulative relative survival ratio showed a 16% excess mortality in patients with a ruptured DACA aneurysm during the first 3 years after SAH compared to the matched general population. From the 4th year onwards, there was no excess mortality during the follow-up period. This 100% follow-up is impossible to replicate in an Indian scenario. It is surprising that no DACA aneurysm was coiled in this large series. Difficulties in coiling these aneurysms have been well documented and consist of principally negotiating the microcatheter into the distal ACA. I have anecdotally operated on a recurrent DACA aneurysm after coiling and found that the coils have to be extracted to allow satisfactory clipping of the aneurysm. Microsurgical clipping of DACA aneurysms provides a long-lasting result with very small rates of rebleeding provided that no residual aneurysm has been left behind. Lastly, all DACA aneurysms need not be clipped/treated as in the case of an associated medial frontal arteriovenous malformation (AVM) illustrated [Figure 1] and [Figure 2]. After successful excision of the AVM, the flow related DACA aneurysms are being monitored and the neurologically intact patient is under regular follow up.
|Figure 1: Lateral cerebral DSA of a 40-year-old female patient presenting with ruptured medial frontal AVM with multiple flow related unruptured DACA aneurysms|
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|Figure 2: Lateral cerebral DSA taken 1 year after the microsurgical excision of the AVM. The distal ACA has regressed in size. The multiple aneurysms are seen to be stable in size. The patient was not willing for a definitive treatment of the aneurysms and is under follow up|
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| » References|| |
Misra BK, Purandare HR, Warade AG. Indocyanine green dye available in India is good for microscope integrated near infrared video angiography. Neurol India 2011;59:321-2.
Lehecka M, Lehto H, Niemelä M, Juvela S, Dashti R, Koivisto T, Ronkainen A, Rinne J, Jääskeläinen JE, Hernesniemi J. Distal anterior cerebral artery aneurysms: Treatment and outcome analysis of 501 patients. Neurosurgery2008:62;590-601.
[Figure 1], [Figure 2]