Intracranial Bypass of Posterior Inferior Cerebellar Artery Aneurysms: Indications, Technical Aspects, and Clinical Outcomes

Abstract BACKGROUND: For some posterior inferior cerebellar artery (PICA) aneurysms, there is no constructive endovascular or direct surgical clipping option. Intracranial bypass is an alternative to a deconstructive technique. OBJECTIVE: To evaluate the clinical features, surgical techniques, and outcome of PICA aneurysms treated with bypass and obliteration of the diseased segment. METHODS: Retrospective review of PICA aneurysms treated via intracranial bypass was performed. Outcome measurements included postoperative stroke, cranial nerve deficits, gastrostomy/tracheostomy requirement, bypass patency, modified Rankin scale (mRS) at discharge, and mRS at 6 mo. RESULTS: Seven patients with PICA aneurysms treated with intracranial bypass were identified. Five had fusiform aneurysms (4 ruptured, 1 unruptured), 1 had a giant partially thrombosed saccular aneurysm (unruptured), and 1 had a dissecting traumatic aneurysm (ruptured). Two aneurysms were at the anteromedullary segment, 4 at the lateral medullary segment, and 1 at the tonsillomedullary segment. Three patients underwent PICA-to-PICA side to side anastomoses, 2 PICA-to-PICA reanastomosis, 1 vertebral artery-to-PICA bypass, and 1 occipital artery-PICA bypass. Six out of 7 aneurysms were obliterated surgically and 1 with additional endovascular occlusion after the bypass. All bypasses were patent intraoperatively; 2 were later demonstrated occluded without radiological signs or symptoms of stroke. No patients had new cranial nerve deficit postoperatively. With the exception of 1 death due to pulmonary emboli 3 mo postoperatively, all others remain at a mRS ≤ 2. CONCLUSION: Constructive bypass and aneurysm obliteration remains a viable alternative for treatment of PICA aneurysms not amenable to direct surgical clipping or to a vessel-preserving endovascular option.

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Anatomical triangles defining surgical routes to posterior inferior cerebellar artery aneurysms

Journal of Neurosurgery ◽

10.3171/2010.8.jns10759 ◽

2011 ◽

Vol 114 (4) ◽

pp. 1088-1094 ◽

Cited By ~ 33

Author(s):

Ana Rodríguez-Hernández ◽

Michael T. Lawton

Keyword(s):

Cranial Nerve ◽

Posterior Inferior Cerebellar Artery ◽

Surgical Morbidity ◽

Surgical Clipping ◽

Cerebellar Artery ◽

Pica Aneurysms

Object Surgical routes to posterior inferior cerebellar artery (PICA) aneurysms are opened between the vagus (cranial nerve [CN] X), accessory (CN XI), and hypoglossal (CN XII) nerves for safe clipping, but these routes have not been systematically defined. The authors describe 3 anatomical triangles and their relationships with PICA aneurysms, routes for surgical clipping, outcomes, and angiographically demonstrated anatomy. Methods The vagoaccesory triangle is defined by CN X superiorly, CN XI laterally, and the medulla medially. It is divided by CN XII into the suprahypoglossal triangle (above CN XII) and the infrahypoglossal triangle (below CN XII). From a consecutive surgical series of 71 PICA aneurysms in 70 patients, 51 aneurysms were analyzed using intraoperative photographs. Results Forty-three PICA aneurysms were located inside the vagoaccessory triangle and 8 were outside. Of the aneurysms inside the vagoaccessory triangle, 22 (51%) were exposed through the suprahypoglossal triangle and 19 (44%) through the infrahypoglossal triangle; 2 were between triangles. The lesions were evenly distributed between the anterior medullary (16 aneurysms), lateral medullary (19 aneurysms), and tonsillomedullary zones (16 aneurysms). Neurological and CN morbidity linked to aneurysms in the suprahypoglossal triangle was similar to that associated with aneurysms in the infrahypoglossal triangle, but no morbidity was associated with PICA aneurysms outside the vagoaccessory triangle. A distal PICA origin on angiography localized the aneurysm to the suprahypoglossal triangle in 71% of patients, and distal PICA aneurysms were localized to the infrahypoglossal triangle or outside the vagoaccessory triangle in 78% of patients. Conclusions The anatomical triangles and zones clarify the borders of operative corridors to PICA aneurysms and define the depth of dissection through the CNs. Deep dissection to aneurysms in the anterior medullary zone traverses CNs X, XI, and XII, whereas shallow dissection to aneurysms in the lateral medullary zone traverses CNs X and XI. Posterior inferior cerebellar artery aneurysms outside the vagoaccessory triangle are frequently distal and superficial to the lower CNs, and associated surgical morbidity is minimal. Angiography may preoperatively localize a PICA aneurysm's triangular anatomy based on the distal PICA origin or distal aneurysm location.

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Endovascular sacrifice of the proximal posterior inferior cerebellar artery for treatment of ruptured intracranial aneurysms

Journal of NeuroInterventional Surgery ◽

10.1136/neurintsurg-2020-016261 ◽

2020 ◽

Vol 12 (8) ◽

pp. 777-782

Author(s):

James G Malcolm ◽

Jonathan A Grossberg ◽

Nealen G Laxpati ◽

Ali Alawieh ◽

Frank C Tong ◽

...

Keyword(s):

Posterior Inferior Cerebellar Artery ◽

High Morbidity ◽

Brainstem Compression ◽

Cerebellar Artery ◽

Diseased Segment ◽

Suboccipital Decompression ◽

Pica Aneurysms ◽

Ruptured Intracranial Aneurysms ◽

Dissecting Aneurysms

BackgroundRuptured aneurysms of the intracranial vertebral artery (VA) or posterior inferior cerebellar artery (PICA) are challenging to treat as they are often dissecting aneurysms necessitating direct sacrifice of the diseased segment, which is thought to carry high morbidity due to brainstem and cerebellar stroke. However, relatively few studies evaluating outcomes following VA or proximal PICA sacrifice exist. We sought to determine the efficacy and outcomes of endovascular VA/PICA sacrifice.MethodsA retrospective series of ruptured VA/PICA aneurysms treated by endovascular sacrifice of the VA (including the PICA origin) or proximal PICA is reviewed. Collected data included demographic, radiologic, clinical, and disability information.ResultsTwenty-one patients were identified. Median age was 57 years (IQR 11); 15 were female. The Hunt and Hess grade was mostly 3 and 4 (18/21). Seven cases (33%) involved VA-V4 at the PICA take-off, and 14 cases (67%) involved the PICA exclusively. For VA pathology, V4 was sacrificed in all cases, while for PICA pathology, sacrificed segments included anterior medullary (4/14), lateral medullary (7/14), and tonsillomedullary (3/14) segments. Four patients went to hospice (19%). Twelve patients (57%) had evidence of stroke on follow-up imaging: cerebellar (8), medullary (1), and both (3). One patient required suboccipital decompression for brainstem compression. No aneurysm re-rupture occurred. Median discharge modified Rankin Scale score was 2.0 (IQR 2), which decreased to 1.0 (IQR 1) at median follow-up of 6.5 months (IQR 23).ConclusionsEndovascular sacrifice of V4 or PICA aneurysms may carry less morbidity than previously thought, and is a viable alternative for poor surgical candidates or those with good collateral perfusion.

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Decision Making in Surgery for Nonsaccular Posterior Inferior Cerebellar Artery Aneurysms With Special Reference to Intraoperative Assessment of Collateral Blood Flow and Neurophysiological Function

Operative Neurosurgery ◽

10.1093/ons/opx141 ◽

2017 ◽

Vol 14 (4) ◽

pp. 422-431 ◽

Cited By ~ 1

Author(s):

Alessandro Narducci ◽

Ran Xu ◽

Peter Vajkoczy

Keyword(s):

Posterior Inferior Cerebellar Artery ◽

Neurophysiological Monitoring ◽

Occipital Artery ◽

Pica Pica ◽

Endovascular Techniques ◽

Vessel Occlusion ◽

Cerebellar Artery ◽

Pica Aneurysms ◽

Intraoperative Test ◽

Time Assessment

Abstract BACKGROUND Posterior inferior cerebellar artery (PICA) aneurysms represent a challenging pathology. PICA sacrifice is often necessary, due to the high proportion of nonsaccular aneurysms that can be found in this location. Several treatments are available, but the infrequency of these aneurysms and the increasing number of endovascular techniques have limited the development of a standardized algorithm for cases in which open surgery is indicated. OBJECTIVE We present our series of nonsaccular PICA aneurysms, in the attempt to define an algorithm for their surgical management. METHODS We retrospectively reviewed the operation database, identifying patients harboring nonsaccular PICA aneurysms who were surgically treated at our institution from 2007 to 2016. RESULTS During a 9-yr period, 17 patients harboring 18 nonsaccular PICA aneurysms were surgically treated at our institution. Fourteen (7.7%) aneurysms were located within the proximal PICA (including those located at the vertebral artery–PICA junction), and 4 were located distally. We performed PICA revascularization in 8 (57.1%) cases of proximal aneurysms (n = 4, PICA–PICA bypass; n = 4, occipital artery–PICA bypass). We based our decision whether to perform bypass on intraoperative test occlusion with indocyanine green (ICG) videoangiography and neurophysiological monitoring. In no cases, bypass was necessary for distal aneurysms. CONCLUSION For nonsaccular PICA aneurysms, in which vessel occlusion is often necessary, it is possible to adopt a selective use of revascularization techniques. Intraoperative occlusion test with ICG videoangiography and neurophysiological monitoring provides reliable indications, allowing real-time assessment of collateral circulation.

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Isolated abducens nerve palsy associated with subarachnoid hemorrhage: a localizing sign of ruptured posterior inferior cerebellar artery aneurysms

Journal of Neurosurgery ◽

10.3171/2017.2.jns162951 ◽

2018 ◽

Vol 128 (6) ◽

pp. 1830-1838 ◽

Cited By ~ 2

Author(s):

Jan-Karl Burkhardt ◽

Ethan A. Winkler ◽

George F. Lasker ◽

John K. Yue ◽

Michael T. Lawton

Keyword(s):

Subarachnoid Hemorrhage ◽

Cranial Nerve ◽

Posterior Inferior Cerebellar Artery ◽

Artery Aneurysm ◽

Abducens Nerve ◽

Dorello’S Canal ◽

Ruptured Aneurysms ◽

Fisher Grade ◽

Cerebellar Artery ◽

Pica Aneurysms

OBJECTIVECompressive cranial nerve syndromes can be useful bedside clues to the diagnosis of an enlarging intracranial aneurysm and can also guide subsequent evaluation, as with an acute oculomotor nerve (cranial nerve [CN] III) palsy that is presumed to be a posterior communicating artery aneurysm and a surgical emergency until proven otherwise. The CN VI has a short cisternal segment from the pontomedullary sulcus to Dorello’s canal, remote from most PICA aneurysms but in the hemodynamic pathway of a rupturing PICA aneurysm that projects toward Dorello’s canal. The authors describe a cranial nerve syndrome for posterior inferior cerebellar artery (PICA) aneurysms that associates subarachnoid hemorrhage (SAH) and an isolated abducens nerve (CN VI) palsy.METHODSClinical and radiological data from 106 surgical patients with PICA aneurysms (66 ruptured and 40 unruptured) were retrospectively reviewed. Data from a group of 174 patients with other aneurysmal SAH (aSAH) were analyzed in a similar manner to control for nonspecific effects of SAH. Univariate statistical analysis compared incidence and risk factors associated with CN VI palsy in subarachnoid hemorrhage.RESULTSOverall, 13 (4.6%) of 280 patients had CN VI palsy at presentation, and all of them had ruptured aneurysms (representing 13 [5.4%] of the 240 cases of ruptured aneurysms). CN VI palsies were observed in 12 patients with ruptured PICA aneurysms (12/66 [18.1%]) and 1 patient with other aSAH (1/174 [0.1%], p < 0.0001). PICA aneurysm location in ruptured aneurysms was an independent predictor for CN VI palsy on multivariate analysis (p = 0.001). PICA aneurysm size was not significantly different in patients with or without CN VI palsy (average size 4.4 mm and 5.2 mm, respectively). Within the PICA aneurysm cohort, modified Fisher grade (p = 0.011) and presence of a thick cisternal SAH (modified Fisher Grades 3 and 4) (p = 0.003) were predictors of CN VI palsy. In all patients with ruptured PICA aneurysms and CN VI palsy, dome projection and presumed direction of rupture were directed toward the ipsilateral and/or contralateral Dorello’s canal, in agreement with laterality of the CN palsy. In patients with bilateral CN VI palsies, a medial projection with extensive subarachnoid blood was observed near bilateral canals.CONCLUSIONSThis study establishes a localizing connection between an isolated CN VI palsy, SAH, and an underlying ruptured PICA aneurysm. CN VI palsy is an important clinical sign in aSAH and when present on initial clinical presentation may be assumed to be due to ruptured PICA aneurysms until proven otherwise. The deficit may be ipsilateral, contralateral, or bilateral and is determined by the direction of the aneurysm dome projection and extent of subarachnoid bleeding toward Dorello’s canal, rather than by direct compression.

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

Operative Neurosurgery ◽

10.1093/ons/opx152 ◽

2017 ◽

Vol 14 (5) ◽

pp. 563-571 ◽

Cited By ~ 2

Author(s):

Ken Matsushima ◽

Satoshi Matsuo ◽

Noritaka Komune ◽

Michihiro Kohno ◽

J Richard Lister

Keyword(s):

Artery Bypass ◽

Posterior Inferior Cerebellar Artery ◽

Jugular Foramen ◽

Occipital Artery ◽

Parent Artery ◽

Microsurgical Anatomy ◽

Main Trunk ◽

Cerebellar Artery ◽

Cerebellomedullary Fissure ◽

Pica Aneurysms

Abstract BACKGROUND 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. OBJECTIVE To examine the microsurgical anatomy involved in occipital artery (OA)-PICA anastomosis at various anatomic segments of the PICA. METHODS 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. RESULTS 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. CONCLUSION 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.

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Dissecting Fusiform PICA Aneurysm Repair With Trapping and an Unconventional End-to-Side Reanastomosis: 2-Dimensional Operative Video

Operative Neurosurgery ◽

10.1093/ons/opab123 ◽

2021 ◽

Author(s):

Fabio A Frisoli ◽

Joshua S Catapano ◽

Rohin Singh ◽

Michael T Lawton

Keyword(s):

Posterior Inferior Cerebellar Artery ◽

Flow Diverter ◽

Fourth Generation ◽

Parent Artery ◽

Recipient Site ◽

Bypass Patency ◽

Cerebellar Artery ◽

Endovascular Approach ◽

Pica Aneurysms ◽

Aneurysm Repair

Abstract Dissecting fusiform posterior inferior cerebellar artery (PICA) aneurysms are rare and challenging.1,2 One common treatment is occlusion of the aneurysm and parent artery via an endovascular approach without revascularization.3 Revascularization of the artery requires an open microsurgical bypass or endovascular placement of a newer-generation flow diverter.4 We present an end-to-side reanastomosis of the PICA for treatment of a dissecting fusiform left PICA aneurysm with anatomy deemed unfavorable for endovascular treatment in a 62-yr-old man with subarachnoid hemorrhage. After discussions regarding risks, benefits, and alternatives to the procedure, the family consented to surgical treatment. A far-lateral craniotomy was performed, with partial condylectomy to widen the exposure. The cisterna magna was opened, and the dentate ligament was cut to visualize the vertebral artery. The PICA was identified and traced distally to the aneurysmal segment, which was circumferentially diseased. Perforators were noted immediately distal to the aneurysm. The aneurysm was then trapped, and the afferent artery was transected and brought to the sidewall of the distal artery. The recipient site was trapped with temporary clips, and a linear arteriotomy was made. An end-to-side reanastomosis was performed, temporary clips were removed, and hemostasis was achieved. Postoperative angiography confirmed bypass patency and preservation of the PICA perforators. Conventional reanastomosis of the parent artery after aneurysm excision is achieved by end-to-end reanastomosis. In contrast, we performed an unconventional end-to-side reanastomosis to revascularize the PICA while leaving the efferent artery in situ to protect its medullary perforators. This bypass is an example of a fourth-generation bypass.5,6 Used with permission from the Barrow Neurological Institute, Phoenix, Arizona.

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Dissecting aneurysms of the posterior inferior cerebellar artery: retrospective evaluation of management and extended follow-up review in 6 patients

Journal of Neurosurgery ◽

10.3171/jns/2008/109/7/0023 ◽

2008 ◽

Vol 109 (1) ◽

pp. 23-27 ◽

Cited By ~ 35

Author(s):

Eric S. Nussbaum ◽

Michael T. Madison ◽

Mark E. Myers ◽

James Goddard ◽

Tariq Janjua

Keyword(s):

Posterior Inferior Cerebellar Artery ◽

Occipital Artery ◽

Management Protocol ◽

Cerebellar Artery ◽

Acute Subarachnoid Hemorrhage ◽

Pica Aneurysms ◽

Proximal Occlusion ◽

Individualized Management ◽

Dissecting Aneurysms

Object The authors report the management protocol and successful outcomes in 6 patients with dissecting aneurysms of the posterior inferior cerebellar artery (PICA). Methods Medical records and neuroimaging studies of 6 patients who underwent surgical treatment of dissecting PICA aneurysms were reviewed. The mean follow-up duration was 1.8 years. No patient was lost to follow-up review. Results Four patients presented with acute subarachnoid hemorrhage and 2 with PICA ischemia. All patients underwent surgery, which entailed proximal occlusion with distal revascularization in 3 cases and circumferential wrap/clip reconstruction in 3 cases. The revascularization techniques used were occipital artery–PICA bypass and PICA–PICA anastomosis. Delayed follow-up angiography was performed in all cases. In patients treated with proximal occlusion, delayed angiography showed minimal retrograde opacification of the dissected segments. The 3 patients treated with wrap/clip reconstruction showed unexpectedly significant normalization of their lesions on angiographic studies. Outcome was good in all cases. Conclusions Dissecting PICA aneurysms are rare lesions with an apparent propensity for bleeding. Individualized management including distal revascularization with PICA sacrifice or circumferential wrap/clip reconstruction to reinforce the dissected segment produced good outcomes. Patients treated with aneurysm wrapping may show dramatic angiographic improvement of the dissected segment.

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Far-Lateral Craniotomy for Posterior Inferior Cerebellar Artery to Occipital Artery Bypass: 2-Dimensional Operative Video

Operative Neurosurgery ◽

10.1093/ons/opz261 ◽

2019 ◽

Vol 17 (6) ◽

pp. E234-E235

Author(s):

Benjamin K Hendricks ◽

Robert F Spetzler

Keyword(s):

Artery Bypass ◽

Video Recording ◽

Posterior Inferior Cerebellar Artery ◽

Careful Consideration ◽

Occipital Artery ◽

Institutional Review Board Approval ◽

Institutional Review ◽

Cerebellar Artery ◽

Far Lateral ◽

Pica Aneurysms

Abstract Posterior inferior cerebellar artery (PICA) aneurysms are infrequent compared with other intracranial aneurysms and are more commonly distal in origin (35% of PICA aneurysms are distal vs 6.5% of other aneurysms). This makes PICA aneurysms a surgical challenge that requires careful consideration of the patient's angiographic anatomy and perfusion needs before deciding on the appropriate intervention. This patient had a highly calcified left PICA p2 segment aneurysm, which was not favorable for endovascular intervention. An end-to-side anastomosis of the occipital artery to the p3 PICA segment was performed. This anastomosis was achieved with 11-0 suture. A permanent clip was then placed along the vertebral artery occluding both the proximal PICA and the aneurysm. Indocyanine green angiography was performed to demonstrate bypass and PICA patency. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

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Surgical clipping of a ruptured posterior inferior cerebellar artery aneurysm

Neurosurgical FOCUS ◽

10.3171/2015.v1.focus14554 ◽

2015 ◽

Vol 38 (videosuppl1) ◽

pp. Video12

Author(s):

M. Yashar S. Kalani ◽

Peter Nakaji ◽

Joseph M. Zabramski ◽

Robert F. Spetzler

Keyword(s):

Posterior Inferior Cerebellar Artery ◽

Cranial Nerves ◽

Artery Aneurysm ◽

Posterior Circulation ◽

Endovascular Techniques ◽

Surgical Clipping ◽

Cerebellar Artery ◽

Posterior Circulation Aneurysms ◽

Pica Aneurysms ◽

Lower Cranial Nerves

Posterior circulation aneurysms are commonly treated with endovascular techniques. In select cases, microsurgery remains an essential tool for treating these lesions. We present a case of a ruptured posterior inferior cerebellar artery (PICA) aneurysm approached via a craniotomy. Given the labyrinth of neurovascular bundles present in the posterior fossa, surgical exposure of PICA aneurysms can be challenging. This video demonstrates the steps of the craniotomy, subarachnoid dissection, mobilization of the vertebral artery and lower cranial nerves, and clipping of the aneurysm.The video can be found here: http://youtu.be/fQSxQj7oL0U.

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Endovascular Surgery for Proximal Posterior Inferior Cerebellar Artery Aneurysms: An Analysis of Glasgow Outcome Score by Hunt-Hess Grades

Neurosurgery ◽

10.1227/01.neu.0000204127.81249.28 ◽

2006 ◽

Vol 58 (4) ◽

pp. 619-625 ◽

Cited By ~ 51

Author(s):

Robert A. Mericle ◽

Adam S. Reig ◽

Matthew V. Burry ◽

Eric Eskioglu ◽

Christopher S. Firment ◽

...

Keyword(s):

Posterior Inferior Cerebellar Artery ◽

Endovascular Surgery ◽

Glasgow Outcome Score ◽

Clinical Grade ◽

Outcome Score ◽

Fisher Grade ◽

Cerebellar Artery ◽

Pica Aneurysms ◽

Angiographic Result

Abstract OBJECTIVE: Proximal posterior inferior cerebellar artery (PICA) aneurysms represent a subset of posterior circulation aneurysms that can be routinely treated with either clipping or coiling. The literature contains limited numbers of patients with proximal PICA aneurysms treated with endovascular surgery. We report our experience with endovascular surgery of proximal PICA aneurysms with emphasis on patients with poor Hunt-Hess grades. METHODS: We reviewed 31 consecutive patients with proximal PICA aneurysms who were treated with endovascular surgery. The following data were analyzed: age, sex, size of aneurysm, Hunt-Hess grade at presentation, Fisher grade at presentation, angiographic result after embolization, complications, number of days hospitalized, duration of follow-up, angiographic follow-up results, and Glasgow Outcome Score at follow-up. RESULTS: Excellent angiographic occlusion was achieved in 30 of 31 (97%) patients. Clinical follow-up with Glasgow Outcome Score was performed on every patient an average of 10 months later. Twenty-one of 31 (68%) patients had good outcomes (Glasgow Outcome Score I or II) at follow-up. Of the patients who presented with a favorable clinical grade (Hunt-Hess 0–III), 13 of 15 (87%) had good outcomes at follow-up. Of the patients who presented with a poor clinical grade (Hunt-Hess Grade IV or higher), 8 of 16 (50%) had good outcomes at follow-up. CONCLUSION: This series demonstrates the safety and efficacy of endovascular surgery for proximal PICA aneurysms. Many patients with poor Hunt-Hess grades from ruptured PICA aneurysms ultimately had a good outcome. This could be secondary to early, aggressive treatment of hydrocephalus and the minimally invasive nature of the endovascular approach.

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