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|Year : 2014 | Volume
| Issue : 1 | Page : 15-18
Long-term outcomes of trapping vertebral artery-posterior inferior cerebellar artery dissecting aneurysms after revascularization
Chongqian Wang1, Xiang-En Shi2, Jinkun Wang1, Bo Wang1, Zhiwei Tang1
1 Department of Neurosurgery, 1st Affiliated Hospital of Kunming Medical University, Kunming 650031, China
2 Department of Neurosurgery, Fu Xing Hospital Affiliated to Capital Medical University, Beijing 100038, China
|Date of Submission||21-Nov-2013|
|Date of Decision||21-Dec-2013|
|Date of Acceptance||02-Feb-2014|
|Date of Web Publication||7-Mar-2014|
Department of Neurosurgery, 1st Affiliated Hospital of Kunming Medical University, 295 Xichang Road, Kunming 650032
Source of Support: This study was funded in part by the National Science Foundation of China (81360204 to Zhiwei Tang), Conflict of Interest: None
Objective: This study is designed to evaluate the long-term outcome of trapping vertebral artery-posterior inferior cerebellar artery (VA-PICA) dissecting aneurysms after revascularization. Materials and Methods: Five patients with VA-PICA dissecting aneurysms were treated surgically between 2007 and 2010. All the aneurysms were trapped through a far-lateral approach after revascularization of the PICAs by occipital artery-posterior inferior cerebellar artery (OA-PICA) bypass. All patients were scheduled for clinical follow-up in the out-patient department at 3 months, 6 months, then annually. Computed tomography (CT) scan and CT angiography, or magnetic resonance (MR) imaging and MR angiography were performed to assess the anastomosis and cerebral blood supply. Results: Among the five patients, two of them did not have any neurological deficit after surgery, the other three had post-operative lower cranial nerve palsy but recovered completely within 6 months. Post-operative cerebral angiography (received by two patients) and CT angiography (received by the other three patients) showed patent bypasses in all patients and there was no reappearance of the aneurysms. After following-up from 47 to 74 months (61 month is the median follow-up period), all patients showed excellent outcomes. Conclusion: Trapping the aneurysms after revascularization of PICAs by OA-PICA bypass is a safe method to treat the VA-PICA dissecting aneurysms.
Keywords: Intracranial aneurysm, occipital artery, posterior inferior cerebellar artery, surgical procedures, vertebral artery
|How to cite this article:|
Wang C, Shi XE, Wang J, Wang B, Tang Z. Long-term outcomes of trapping vertebral artery-posterior inferior cerebellar artery dissecting aneurysms after revascularization. Neurol India 2014;62:15-8
|How to cite this URL:|
Wang C, Shi XE, Wang J, Wang B, Tang Z. Long-term outcomes of trapping vertebral artery-posterior inferior cerebellar artery dissecting aneurysms after revascularization. Neurol India [serial online] 2014 [cited 2019 Sep 18];62:15-8. Available from: http://www.neurologyindia.com/text.asp?2014/62/1/15/128247
| » Introduction|| |
Vertebral artery-posterior inferior cerebellar artery (VA-PICA) dissecting aneurysms are rare, but surgery for these aneurysms is challenging because the dissecting VA aneurysms involve the origin of PICA. The PICA gives rise to the perforating arteries to supply blood to the brainstem and cerebellum and damages to these vessels may lead to infarction of their respective territory after surgical treatment, hence necessitate PICA revascularization. In this paper, we report our surgical performance to trap the aneurysms after PICA revascularization by occipital artery (OA) -PICA bypass and the long term post-operative outcomes of patients.
| » Clinic Profiles of Patients|| |
Between November 2007 and February 2010, five patients with VA-PICA dissecting aneurysms were treated in our institute. All patients were males with a mean age of 47 years (ranging from 40 to 55 years), four of them presented with subarachnoid hemorrhage (SAH) upon admission, the other one presented with a 4 month history of intermittent occipital headache. Among the four SAH patients with ruptured VA-PICA aneurysms, one was classified grade? I on the Hunt-Hess scale at the time of treatment and the other three were grade??. The mean interval between SAH onset and the surgical treatment was 22 days (range from 6 days to 49 days). Based on the cerebral angiographical assessment, the dissecting VA aneurysms in all patients involved the origin of PICA on the right VA.
| » Surgical Procedure|| |
We performed far-lateral approach in all cases. Patients were placed in the lateral position and the heads were fixed in my field head frame with the ipsilateral external auditory meatus and the mastoid bone was placed at the highest point. The inverted J-shaped incision starts from approximate C5 and extends rostrally along the posterior median line until 2 cm above the external occipital protuberance. Then the incision curves to the mastoid prominence. After elevating the skin and muscles flap in a single layer, we could find the amputated end of OA at the edge of the incision. Then we dissected OA along its path by cutting the occipital muscles until reaching the OA sulcus at the mastoid prominence. We then performed the lateral suboccipital craniectomy, extending to the inferior nuchal line superiorly, the midline medially, the posterior rim of the foramen magnum inferiorly and the occipital condyle laterally. Then we resected the ipsilateral C1 posterior arch, the inferior part of the mastoid, about 1/3 of the occipital condyle and opened the foramen magnum. The VA aneurysm with its parent artery and the PICA could be exposed adequately after the cerebellar hemisphere and the tonsil were lifted superomedially and the lower cranial nerves surrounding the aneurysm were visualized at this step. Here, we temporarily clipped the caudal loop of PICA and anastomosed the OA end to the PICA side. The VA was deflated by sequentially clipping the proximal and the distal side of the aneurysm and the PICA was occluded by clipping upstream the anastomosis at its origin. If the aneurysm was huge, we resected the aneurysm to relieve its pressure on the brain stem [Figure 1].
|Figure 1: A procedure of trapping the vertebral artery-posterior inferior cerebellar artery (PICA) aneurysms after revascularization of PICAs by occipital artery -PICA bypass|
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| » Clinical Follow-up and Imaging Evaluation|| |
All five patients were scheduled for clinical follow-up in the outpatient department at post-operative 3 months, 6 months and annually. Angiographic evaluation was carried out at 6 month after the surgery. Computed tomography (CT) scan plus CT angiography, or magnetic resonance (MR) imaging plus MR angiography were ordered to assess the anastomosis and the cerebral blood supply. We assessed the Glasgow Outcome Score for patients on every follow-up visit. We discussed the results of clinical and angiographic evaluation and potential consequences with patients to decide the need for additional management.
| » Results|| |
On the 1 st day, all the patients woke up completely after surgery. Three of them had complications of lower cranial nerve palsy (LCNP), whereas the other two had no complications. At 1 week after the surgery, the symptoms of LCNP in the three patients became a little bit severer than those of the 1 st day and the other two patients still exhibited no neurological deficit. At this time point, initial post-operative cerebral angiography was ordered in two patients and CT angiography in three patients, showing patent bypasses and no filling of the aneurysms was seen [Figure 2].
|Figure 2: (a) Cerebral angiography displaying the right dissecting vertebral artery (VA) aneurysm involving the origin of posterior inferior cerebellar artery (PICA). (b) Intra-operative photograph showing the dissecting aneurysm involving the origin of PICA. (c) Intra-operative photograph showing permanently clipped proximal and distal edges of VA after resection of the aneurysm and the black arrow pointing the occipital artery (OA) -PICA anastomotic site. (d) Post-operative cerebral|
angiography displaying the patent anastomosis 1 week after the surgery (short black arrow: Aneurysm; long black arrow: Anastomotic site; short white arrow: OA; long white arrow: PICA)
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After a mean period of 61 months follow-up (range from 47 to 74 months), the follow-up imaging studies showed that all the bypasses are patient with no infarction [Figure 3]. And the clinical assessment of all the patients showed the complete absence of neurological deficits.
|Figure 3: Computed tomography angiography after 56 months follow-up, arrow showing the patent anastomosis (long black arrow: Anastomotic site; short white arrow: Occipital artery [OA]; long white arrow: Posterior inferior cerebellar artery [PICA])|
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| » Discussion|| |
In this study, we found that trapping the aneurysms after OA-PICA bypasses is an effective surgical intervention for VA-PICA dissecting aneurysms. All five patients survived, three of them live without any neurological deficit in the follow-up periods, two patients had only mild LCNP 3 months after the surgery, but has completely recovered after 6 months. In general, all patients with the VA-PICA dissecting aneurysms have good outcomes in the long-term.
Although VA-PICA dissecting aneurysms are rare cases among all the cerebral aneurysms, they have a high risk of rupture or subsequent rupture, leading to high mortality and significant neurological deficit for most survivors. ,,, In our study, four of five patients presented with SAH due to the rupture of aneurysms. Aggressive treatment should be performed to prevent the recurrent SAH and improve the outcome. Because VA-PICA dissecting aneurysms involve the origin of PICA and the brainstem perforating branches arise from the proximal PICA, therefore revascularization of PICA to prevent lateral medullary and cerebellar infarction is an optimal strategy. ,
OA-PICA bypass is the major method to revascularize PICA. ,, The OA suboccipital segment has a mean diameter of 1.9 mm and an average length of 79.3 mm. The mean distance between the OA and the external occipital protuberance was 45 mm and the mean diameter of the caudal loop of PICA was 1.2 mm, which makes it an ideal donor artery for OA-PICA bypass.  In our study, the mean diameter of the OA suboccipital segment was 2.2 mm, the mean length was 88.0 mm, the mean diameter of the caudal loop of PICA was 1.2 mm which also demonstrated that OA is an ideal donor artery for OA-PICA bypass. However, using OA as a donor artery is inconvenient because it has many branches, located deep to the muscles and difficult to dissect.
PICA-PICA bypass has been used to revascularize PICA. , The proximity and parallel course of the bilateral caudal loops of PICA make it possible to perform a side-to-side anastomosis and the calibers of the posterior medullary segments of PICAs are relatively consistent. However, this type of bypass is associated with an ischemic risk to the territories of both PICAs.  Alternatively, some surgeons use VA-PICA transposition to revascularize PICA. , Brainstem perforating branches arise from the proximal segment of PICA, which makes PICA mobilization really difficult and performing VA-PICA anastomosis in deep and narrow operative field is a challenging and complicated procedure. Placing a graft vessel between VA and PICA, such as VA-radial artery-PICA, or VA-superficial temporal artery-PICA is another method to revascularize PICA. , The graft vessel is easy to harvest with sufficient length. However, performing double anastomoses increases the risk of stenosis and technical difficulty.
Post-operative LCNP is a common complication of the surgical treatment for VA-PICA aneurysms due to the close proximity of the aneurysm with the glossopharyngeal vagal and accessory nerves. This close position increases the possibility of injuring the lower cranial nerves during the surgical procedure. The outcome of post-operative LCNP is good: A)bout 48% of patients resolved completely within 3 months and about 76% of them within 6 months according to the report by Al-khayat et al.  In our study, 3 of 5 patients had LCNP, but all of them completely recovered within 6 months after surgery. Knowledge about the natural history of post-operative LCNP will help neurosurgeons to make effective clinical decision.
| » Conclusion|| |
In this study, we performed OA-PICA bypass for patients with the VA-PICA dissecting aneurysms. All the bypasses are patent and there is no filling of the aneurysms after the surgery and the clinical functional outcomes are excellent. We recommend that trapping the aneurysms after revascularization of PICAs by OA-PICA bypass is an effective surgical treatment for the VA-PICA aneurysms, but individualized strategies also need to be considered based on specific cases.
| » Acknowledgments|| |
This study was funded in part by the National Science Foundation of China (81360204 to Zhiwei Tang). We thank Dr. P. Han at Barrow Neurological Institute for helping with the manuscript preparation.
| » References|| |
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[Figure 1], [Figure 2], [Figure 3]
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