Occipital Artery-posterior Inferior Cerebellar Artery Research Articles

The occipital artery: a meta-analysis of its anatomy with clinical correlations.

The occipital artery arises as one of the main branches of the external carotid artery. The goal of the present meta-analysis was to provide a detailed analysis of the complete anatomy of the occipital artery using the available data in the literature. The main online medical databases such as PubMed, Embase, Scopus, Web of Science, Cochrane Library, and Google Scholar were used to gather all studies on anatomical variations, course, branches, and the close anatomical area of the occipital artery. A total of 65 studies were indicated, evaluated, and included in this meta-analysis. The occipital artery was found to run in the groove with a prevalence of 83.93% (95% confidence intervals: 50.53-100.00%). The occipital artery forming a common trunk with another artery had a prevalence of 13.91% (95% confidence intervals: 9.15-19.47%). The mean maximal diameter of the occipital artery was set to 2.26mm (standard error = 0.15). The mean maximal diameter of the occipital segment of the occipital artery was found to be 1.24mm (standard error = 0.15). The mean occipital artery length was set to 131.93mm (standard error = 3.02). In conclusion, the authors of the present study believe that this is the most accurate and up-to-date meta-analysis regarding the anatomy of the occipital artery. Knowledge about this structure can be of great use when performing revascularization procedures, such as the occipital artery-posterior inferior cerebellar artery bypass, or reconstructive procedures, such as the occipital artery fascial flap.

Microsurgical Treatment of Vertebral Artery Dissection: Surgical Strategies and Treatment Outcomes

Vertebral artery dissection (VAD) is a rare cerebrovascular disease that can lead to permanent morbidity or mortality. Open surgery for VAD is challenging; therefore, most cases are managed via endovascular techniques. There are several surgical methods for VAD treatment, including trapping or proximal occlusion with or without bypass; however, the standard treatment protocol is not well established. The aims of this study were to demonstrate surgical strategies, surgical outcomes, and complications of each method and to propose an algorithm to select the appropriate procedure. This study included 22 patients with VAD who underwent open surgical treatment between January 2015 and December 2019 and were retrospectively reviewed and evaluated for postoperative outcomes and complications. Proximal occlusion, trapping, occipital artery-posterior inferior cerebellar artery (PICA) bypass with blind-alley formation, and occipital artery-PICA with trapping were performed in 13, 2, 5, and 2 patients. The surgical procedure depended on the type of VAD: pre-PICA, PICA, post-PICA, and non-PICA. All VADs were completely obliterated after surgery. Obliteration occurred immediately for 18 patients (81.8%) and within 1 week for 4 patients (18.2%). There was no postoperative bleeding or PICA infarction. Favorable outcome at 3 months after operation was achieved in 100% for good-grade patients and 86.4% overall. Open surgery can be a safe and effective treatment of VAD when surgical strategies are carefully selected. Angioarchitecture and the type of VAD influence the selection of the surgical method.

Ruptured vertebral artery dissecting aneurysms involving a dominant posterior inferior cerebellar artery origin: A preferred indication for bypass surgery in clinical practice

BackgroundIn clinical practice, the optimal treatment approach for ruptured vertebral artery dissecting aneurysm (VADA) involving a posterior inferior cerebellar artery (PICA) remains unclear. Here, we report two cases of ruptured VADA involving a dominant PICA that were successfully treated with surgical occlusion with occipital artery (OA) to PICA bypass, while avoiding postoperative ischemia. Case descriptionThe first patient was a 47-year-old woman who presented with a Hunt–Hess grade III, diffuse subarachnoid hemorrhage (SAH) due to a ruptured right VADA involving a PICA. The PICA was dominant, supplying a wide vascular territory in the right cerebellum (the “PICA–anterior inferior cerebellar artery” variant). The second patient was a 56-year-old man who presented with a Hunt–Hess grade II, localized SAH due to a ruptured right VADA involving a PICA. The PICA was also dominant, supplying a wide vascular territory in the bilateral cerebellum (the “bihemispheric PICA” variant). Both patients were treated with OA–PICA bypass, which was followed by surgical trapping of the VADA in the first patient and proximal clipping in the second patient on the day of the SAH onset. The postoperative course was uneventful, and magnetic resonance imaging showed no apparent ischemic change in the brainstem and cerebellum in either patient. ConclusionsFor ruptured VADA involving a PICA, dominance of the involved PICA may be a practically preferred indication for bypass surgery because of the severity of ischemia when a dominant PICA is sacrificed and because the vascular anatomy of a dominant PICA makes anastomosis feasible.

Blind-Alley Formation and Occipital Artery-Posterior Inferior Cerebellar Artery Bypass for the Treatment of Unclippable Vertebral Artery Aneurysms with Posterior Inferior Cerebellar Artery Involvement

Unclippable vertebral artery aneurysms (UVAs) are difficult to treat with direct clipping, especially in cases involving the origin of the posterior inferior cerebellar artery (PICA). Bypass with trapping is the common procedure used for these conditions. The authors used the blind-alley formation technique, which is a simpler method than trapping and can avoid some complications. To report 7 cases of UVA with PICA involvement treated with blind-alley formation and occipital artery (OA)-PICA bypass as well as their surgical outcomes and complications and to describe the operative techniques. Seven patients with UVA and PICA involvement underwent OA-PICA bypass and blind-alley formation (occlusions of the PICA origin and vertebral artery proximal to the aneurysm). Vertebral artery dissecting aneurysms and fusiform atherosclerotic vertebral artery aneurysms were detected in 6 patients and 1 patient, respectively. All patients presented with subarachnoid hemorrhage, and 71.4% of them were classified into the poor-grade group. Good bypass patency and complete aneurysm obliteration were achieved in all cases. Six aneurysms (85.7%) were completely obliterated according to computed tomography angiography performed immediately postoperatively. Another aneurysm was 50% and 100% thrombosed immediately and at 7 days after the operation, respectively. Surgical complications were found in 1 patient (14.3%) who had postoperative diparesis with dysphagia. Three patients (42.9%) achieved a Glasgow Outcome Score of 4 or 5 one month after the operation. Blind-alley formation and OA-PICA bypass are simple, safe, and effective for the treatment of patients with UVA with PICA involvement.

Treatment of Vertebral Artery Aneurysm with OA-PICA Bypass in the Prone Position

The occipital artery-posterior inferior cerebellar artery (OA-PICA) bypass is a well-known surgical technique for the treatment of vertebral artery (VA) aneurysms involving the PICA. However, the OA-PICA bypass is considered to be a difficult procedure owing to the deep operative field and the proximity of the lower cranial nerves. The mid-lateral suboccipital approach allows for the establishment of a wide and superficial operative field reliably and safely.

Surgical Strategies for Ruptured Complex Aneurysms Using Skull Base Technique and Revascularization Surgeries.

Object:Surgical clipping of paraclinoid aneurysm, thrombosed large aneurysm, and/or vertebral-basilar dissecting aneurysms can be very difficult and has relatively high morbidity. We describe our experience using skull base and bypass technique and discuss the advantages and its pitfalls.Patients and Methods:We retrospectively reviewed medical charts of 22 consecutive patients with complex aneurysmal lesions underwent skull base and/or bypass techniques between March 2012 and April 2017.Results:There were 5 patients with paraclinoid or internal carotid artery (ICA) aneurysm underwent modified extradural temporopolar approach with mini-peeling of the dura propria with suction decompression, 3 patients with ICA aneurysm underwent intradural anterior clinoidectomy, 12 patients with vertebral dissecting aneurysm through transcondylar fossa approach (6 patients underwent occipital artery-posterior inferior cerebellar artery [OA-PICA] bypass), 1 patients with vertebral artery dissection underwent superficial temporal artery-superior cerebellar artery and OA-PICA bypass through posterior transpetrosal approach, 1 patient with arteriovenous fistula at the ventral side of the craniovertebral junction through extremely far lateral approach. Surgical outcome was good recovery in 10 patients, moderate disability in 4, severe disability in 4, vegetative state in 2, and dead is 2 patients. The favorable outcome was 63.6%, and poor outcome was 36.4%, which showed poor grade subarachnoid hemorrhagic patients. No patient suffered any complication related to re-rupture and/or incomplete clipping.Conclusion:Skull base technique, which can create a wide and shallow operative space, allowed us to improve surgical outcome and to reduce the risk of intraoperative neurovascular injury for surgical treatment of deeply located complex aneurysms.

Variations of Occipital Artery-Posterior Inferior Cerebellar Artery Bypass: Anatomic Consideration.

Advances in diagnosis of posterior inferior cerebellar artery (PICA) aneurysms have revealed the high frequency of distal and/or dissecting PICA aneurysms. Surgical treatment of such aneurysms often requires revascularization of the PICA including but not limited to its caudal loop. To examine the microsurgical anatomy involved in occipital artery (OA)-PICA anastomosis at various anatomic segments of the PICA. Twenty-eight PICAs in 15 cadaveric heads were examined with the operating microscope to take morphometric measurements and explore the specific anatomy of bypass procedures. OA bypass to the p2, p3, p4, or p5 segment was feasible with a recipient vessel of sufficient diameter. The loop wandering near the jugular foramen in the p2 segment provided sufficient length without requiring cauterization of any perforating arteries to the brainstem. Wide dissection of the cerebellomedullary fissure provided sufficient exposure for the examination of some p3 segments and all p4 segments hidden by the tonsil. OA-p5 bypass was placed at the main trunk before the bifurcation in 5 hemispheres and at the larger hemispheric trunk in others. Understanding the possible variations of OA-PICA bypass may enable revascularization of the appropriate portion of the PICA when the parent artery must be occluded. A detailed anatomic understanding of each segment clarifies important technical nuances for the bypass on each segment. Dissection of the cerebellomedullary fissure helps to achieve sufficient exposure for the bypass procedures on most of the segments.

Management strategy for bilateral complex vertebral artery aneurysms.

Bilateral complex vertebral artery aneurysms (BCoVAAns) have no established strategy of management. We retrospectively reviewed five consecutive patients with unruptured BCoVAAns between January 2006 and December 2012. Considering surgical risks of lower cranial nerve (LCN) injuries and eventual growth of an opposite side lesion after unilateral vertebral artery (VA) occlusion, we proposed a strategy of combined open and interventional treatment using revascularization. We applied the following several specific techniques: (1) proximal clipping and occipital artery-posterior inferior cerebellar artery (OA-PICA) and/or superficial temporary artery (STA)-superior cerebellar artery (SCA) bypasses; (2) Distal blood pressure, motor evoked potentials (MEPs), and somatosensory evoked potentials (SEPs) monitoring after parent artery temporary occlusion for safe permanent occlusion of the proximal portions of VA and PICA; (3) V3 to V4 bypass using radial artery (RA) graft with proximal clipping or trapping, two of them combined with OA-PICA bypass; (4) VA fenestration as an opportunity to preserve the flow of the parent artery. Two patients were treated bilaterally and 3 unilaterally, with modified Rankin scale assessed at 39 months postoperatively in average 0 in 2, 1 in 2, and 2 in 1, respectively, and the untreated opposite side lesions without regrowth or bleeding. Two patients with patent V3-RA-V4 bypass complained of dysphagia due to LCN palsies. One of them however suffered a cerebellar infarction due to occlusion of the OA-PICA bypass. When BCoVAAns require surgical treatment, revascularization or preservation of the VA should be considered at the first operation. By doing so, the opposite aneurysm can be effectively occluded by coil embolization, even with VA sacrifice if required.

Long-term outcomes of trapping vertebral artery-posterior inferior cerebellar artery dissecting aneurysms after revascularization

This study is designed to evaluate the long-term outcome of trapping vertebral artery-posterior inferior cerebellar artery (VA-PICA) dissecting aneurysms after revascularization. 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. 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. Trapping the aneurysms after revascularization of PICAs by OA-PICA bypass is a safe method to treat the VA-PICA dissecting aneurysms.

Posterior Circulation Extracranial-Intracranial Bypass

Experience of various types of extracranial-intracranial (EC-IC) bypass for the posterior circulation is presented; subtemporal superficial temporal artery-supracerebellar artery (STA-SCA) bypass,18 paramedian suboccipital occipital artery-posterior inferior cerebellar artery OA-PICA bypass,10 and occipital artery-posterior cerebral artery OA-PCA bypass, and/or OA-SCA bypass via the paramedian suboccipital supracerebellar transtentorial (SCTT) approach8 and other bypasses including saphenous vein interposition graft.9 The author have experienced 45 surgeries of these kinds on 44 patients, while around 500 EC/IC bypasses for the anterior circulation have been performed in the same period. The series includes cases of eight intractable aneurysms and two of moyamoya angiopathy besides most cases of vertebrobasilar occlusive disease. Indication of such surgeries and their results along with technical consideration by representing typical cases are described and discussed.

脳血管バイパス術 手術初心者によるガーゼおよびチューブを用いた手術訓練の血行再建術における効能

We describe microsurgical training methods for novice operators using gauze and tubes. Seven training methods were designed, and a neurosurgeon without microsurgical experience practiced these methods every day for about 3 years. After completing training, the neurosurgeon performed superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis, A3-A3 bypass, and occipital artery-posterior inferior cerebellar artery (OA-PICA) bypass. These training methods contribute to improving microsurgical technique, especially microvascular anastomosis, of novice operators.

Surgical treatment of vertebral artery-posterior inferior cerebellar artery dissecting aneurysms

To study an effective method for vertebral artery-posterior inferior cerebellar artery (VA-PICA) dissecting aneurysms. Five patients with VA-PICA dissecting aneurysms were treated surgically between December 2007 and February 2010, who were all males, aged from 40 to 55 years. Four of them presented with subarachnoid hemorrhage (SAH), 1 of them suffered from an intermittent headache on occipital area about 4 months. All the aneurysms were trapped via a far-lateral approach after revascularization of the PICAs by occipital artery-posterior inferior cerebellar artery (OA-PICA) bypass. Among the 5 patients, 1 of them got a good outcome without any neurological deficit after surgery, 3 of them had postoperative lower cranial nerve palsy, 1 of them complicated with bleeding in the operative field after postoperative antithrombotic treatment, and suffered from contralateral hemiplegia after second surgery of removing hematoma. Postoperative cerebral angiographies (received by 2 patients) and CT angiographies (received by 3 patients) all showed patent bypasses and no filling of the aneurysms. During the follow-up from 2 to 29 months, 4 patients got good outcomes, 1 patient still suffered from moderate hemiplegia. Trapping the aneurysms after revascularization of PICA by OA-PICA bypass should be an effective method to treat the VA-PICA dissecting aneurysms, but individualized strategies also need to be considered based on different cases.

Fluorescein sodiumを用いた術中蛍光脳血管撮影による脳血流の評価

We evaluated the usefulness of fluorescence cerebral angiography using fluorescein sodium (fluorescein-FCAG) for detecting the blood flow in the cerebral artery and vein during neurological surgery. The study population comprised 81 patients who underwent aneurysm clipping (76 cases), superficial temporal artery-middle cerebral artery anastomosis (4 cases) and occipital artery-posterior inferior cerebellar artery anastomosis (1 case). After aneurysm clipping and/or anastomosis, the target arteries were illuminated using a beam from a pencil-type probe with a blue light-emitting diode at its tip. After a 2.5-5 ml of 10% fluorescein sodium was injected intravenously, fluorescence in the vessels was clearly observed through a microscope and recorded on videotape. The excellent image quality and spatial resolution of fluorescence facilitated intraoperative real-time assessment of the patency of the target arteries. In large arteries such as internal cerebral artery, images by FCAG using indocyanine green (ICG-FCAG) were clearer than those by fluorescein-FCAG. On the other hand, in perforating arteries, fluorescein-FCAG was superior to ICG-FCAG in resolution. The fluorescence by fluorescein-FCAG disappeared faster than that when ICG-FCAG was used. Fluorescein-FCAG is very promising because it allows confirmation of the intravascular blood flow from outside. Our findings suggest that observation of the blood flow by fluorescein-FCAG can prevent unexpected cerebral infarctions and improve the surgical outcome.

Microsurgical anatomy of cerebral revascularization. Part II: Posterior circulation

Revascularization is an important component of treatment for complex aneurysms, skull base tumors, and vertebrobasilar ischemia in the posterior circulation. In this study, the authors examined the microsurgical anatomy related to cerebral revascularization in the posterior circulation and demonstrate various procedures for bypass surgery. The microsurgical anatomy of cerebral and cerebellar vessels as they relate to revascularization procedure and techniques, including extracranial-to-intracranial bypass grafting, arterial interposition grafting, and side-to-side anastomosis, were examined by performing stepwise dissections in 22 adult cadaveric specimens. The arteries and veins in the specimens were perfused with colored silicone. Dominant cerebral and cerebellar revascularization procedures in the posterior circulations include superficial temporal artery (STA)-posterior cerebral artery (PCA), STA-superior cerebellar artery (SCA), occipital artery (OA)-anterior inferior cerebellar artery, OA-posterior inferior cerebellar artery (PICA), and PICA-PICA anastomoses. These procedures are effective in relatively small but critical areas including the brainstem and cerebellum. For revascularization of larger areas a saphenous vein graft is used to create a bypass between the PCA and the external carotid artery. Surgical procedures are generally difficult to perform in deep and narrow operative spaces near critical vital structures. Although a clear guideline for cerebral revascularization procedures has not yet been established, it is important to understand various microsurgical techniques and their related anatomical structures. This will help surgeons consider surgical indications for treatment of patients with vertebrobasilar ischemia caused by aneurysms, tumors, or atherosclerotic diseases in the posterior circulation.