NI FEATURE: THE EDITORIAL DEBATE-- PROS AND CONS
|Year : 2016 | Volume
| Issue : 6 | Page : 1147--1148
Distal anterior cerebral artery aneurysms: Surgical tips
Vijendra K Jain
Department of Neurosurgery, Max Hospital, Saket, New Delhi, India
Vijendra K Jain
Department of Neurosurgery, Max Hospital, Saket, New Delhi
|How to cite this article:|
Jain VK. Distal anterior cerebral artery aneurysms: Surgical tips.Neurol India 2016;64:1147-1148
|How to cite this URL:|
Jain VK. Distal anterior cerebral artery aneurysms: Surgical tips. Neurol India [serial online] 2016 [cited 2019 Sep 20 ];64:1147-1148
Available from: http://www.neurologyindia.com/text.asp?2016/64/6/1147/193766
Distal anterior cerebral artery (DACA) aneurysms are uncommon. Therefore, they pose a challenge to surgeons who have less experience with aneurysm surgery. Surgeons who have been performing aneurysm surgery and interhemispheric approach for third ventricular tumors, a DACA aneurysm does not usually pose significant problems.
Planning of craniotomy is very important in these cases. One can draw a line of the shortest distance from the aneurysm to the inner table of the skull and then perform a craniotomy 2–3 cm anterior and posterior to this point. Although some surgeons have performed a bifrontal craniotomy, as reported in the present article, many surgeons, including myself, always perform a right parasagittal craniotomy except when a left-sided craniotomy is necessary to remove an intracerebral hematoma situated on that side. The parasagittal craniotomy should always extend to the midline medially. Sometimes, one is required to perform a pterional craniotomy for a much proximal, i.e., an A2 segment aneurysm. The trajectory angle of the microscope should be planned at the time of the final positioning of the head in a fixation device. This trajectory should be remembered well after the draping has been done.
After the craniotomy, the brain may be made lax by opening the medial sylvian fissure, carotico-chiasmatic cistern, or lamina terminalis, if the pterional approach is used. This can sometimes be achieved by removing a part of the hematoma or tapping the ventricle in the parasagittal craniotomy. Draining of cerebrospinal fluid from the callosal cistern is at times a patient job and may become tedious particularly when there are adhesions between the cingulate gyri on either side. Corpus callosum may be punctured by bipolar forceps to drain the cerebrospinal fluid from the lateral ventricle.
Reaching up to the pericallosal arteries through the interhemispheric approach is the standard technique except that one should carefully decide the direction of the fundus of the aneurysm according to the preparative angiogram. Depending on this, the cingulate gyrus opposite to the direction of fundus should be retracted while dissecting the pericallosal arteries and the neck of the aneurysm. Thus, the initial dissection should always be on the side of the normal artery. Uncommonly, the aneurysm is directed towards the side of the normal artery. One must always proceed with dissection of the artery on the normal side, and during its dissection, one reaches the proximal segment of the artery bearing the aneurysm. Once proximal portion of the artery bearing the aneurysm has been prepared, the surgeon should come back to prepare the artery distal to the aneurysm. Now, the surgeon has to ensure that the proximal and distal portions of the aneurysm bearing artery are seen simultaneously on the microscopic field before starting the dissection of the aneurysm, so that in case of rupture of the aneurysm, proximal and distal clips may be applied without moving the microscope. This is not possible in an aneurysm of the A3 portion located at the junction of inferior and superior surfaces of the genu of corpus callosum. In such cases, a small portion of the genu of corpus callosum can be resected to visualize the proximal artery from the superoinferior direction rather than moving the microscope to gain access to the inferosuperior direction for placement of a temporary clip on the artery proximal to the aneurysm.
Finally dissection around the aneurysm is started. Throughout the dissection, the arachnoidal bands should be sharply cut with scissors rather than broken with a microdissector. This is to prevent any inadvertent movement of the aneurysm and its rupture. Initially, the neck and the adjoining vessels are dissected. Sometimes, when the aneurysm is adherent or buried in the cingulate gyrus and the neck cannot be properly dissected, one has to perform a subpial dissection of the aneurysm dome to properly visualize the neck of the aneurysm.
Sometimes, the aneurysm is directed to the opposite cingulate gyrus, e.g., a right pericallosal artery aneurysm directed and adherent to the left cingulate gyrus. In this situation, the aneurysm may be adherent to the left pericallosal artery/branch, which is hidden from the view. In such situations, a very careful subpial resection of the aneurysm has to be done to free the aneurysm from these vessels and then the clip is placed across its neck.
In case of an intraoperative rupture of the aneurysm, a small temporary clip can be applied on the aneurysm itself to perform further dissection or a proximal temporary clip may be applied along with the distal temporary clip.
In the rare event of intraoperative rupture at the neck of the aneurysm, which cannot be clipped without blocking the artery or cannot be repaired by sutures, one should be ready to carry out the anastomosis of the pericallosal artery.