Original Article
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Endovascular Treatment of Ruptured Distal Posterior Inferior Cerebellar Artery Aneurysm. Report of Two Exemplary Cases and Retrospective Analysis of 11 Cases Seung Hwan Lee1
Jun Seok Koh1
1 Department of Neurosurgery, Kyung Hee University Hospital at
Gangdong, College of Medicine, Kyung Hee University, Seoul, Republic of Korea
Address for correspondence Seung Hwan Lee, MD, PhD, Department of Neurosurgery, Kyung Hee University Hospital at Gangdong, College of Medicine, Kyung Hee University, 134-090, Sangil-Dong 149, Gangdong-Gu Seoul, Republic of Korea (e-mail: [email protected]).
J Neurol Surg A 2014;75:343–349.
Abstract
Keywords
► distal PICA aneurysm ► endovascular treatment ► subarachnoid hemorrhage
received October 29, 2013 accepted after revision February 11, 2014 published online May 12, 2014
Background and Purpose Although endovascular therapy for intracranial aneurysms has recently started to replace surgical treatment and literature regarding endovascular therapy’s advantages and disadvantages is being published, literature concerning the endovascular treatment of distal posterior inferior cerebellar artery (PICA) aneurysms specifically limited to rupture are lacking. We describe the clinical characteristics of ruptured distal PICA aneurysms, their clinical outcomes, and the strategies in which endovascular treatment are used. Patients and Methods Eleven consecutive patients with ruptured distal PICA aneurysm with at least 1 year of follow-up were retrospectively reviewed. Clinical profiles and radiologic and interventional methods were analyzed. Results The mean age at the time of treatment was 56.3 years (range: 30–86 years). The 11 patients consisted of 8 women (72.7%) and 3 men (27.3%). Six patients had a saccular aneurysm; 5 had a dissecting aneurysm. The aneurysms were located at the lateral medullary segment (n ¼ 5), telovelotonsillar segment (n ¼ 4), and tonsillomedullary segment (n ¼ 2). The mean maximal aneurysm diameter was 6.5 3.1 mm (range: 3.4–12.7 mm). Of the 11 aneurysms, 6 were treated with pure aneurysm coiling, 4 were treated with coil trapping, and 1 was treated with stent-assisted coiling. Complete aneurysm obliteration was achieved in nine patients (pure coiling: five, coil trapping: three, stent-assisted coiling: one), and a residual neck was found in two patients (pure coiling: two). Good outcomes (Glasgow Outcome Scale [GOS] of 4 or 5) were achieved in nine patients (pure coiling: five, coil trapping: four), a GOS of 3 was recorded in one patient (stent-assisted coiling), and one patient (pure coiling) had a GOS of 1. Conclusion The present data suggest that endovascular treatment for ruptured distal PICA aneurysms is a safe and effective treatment modality under an elaborate treatment plan.
© 2014 Georg Thieme Verlag KG Stuttgart · New York
DOI http://dx.doi.org/ 10.1055/s-0034-1373665. ISSN 2193-6315.
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Hee Sup Shin1
Endovascular Treatment of Ruptured Distal PICA Aneurysm
Introduction Aneurysms of the posterior inferior cerebellar artery (PICA) are rare but often lethal due to proximity to the brainstem1,2 and a high rebleeding rate.3 PICA aneurysms account for 0.5 to 3.0% of all intracranial aneurysms,4,5 and their rebleeding rate is reported to be as high as 78%.6 Distal PICA aneurysms are found to constitute only about a fifth of all PICA aneurysms5,7–9 and are associated with a dissection rate as high as 58%.8 Despite recent advancements in microsurgery with highquality optical devices, surgical treatment of these aneurysms is not always successful due to the complex neurovascular structural relationship with the brainstem and low cranial nerves such as IX, X, and XI.1,2,8,10,11 Alternatively, endovascular treatment is becoming more frequently used in the treatment of surgically inaccessible or difficult lesions; distal PICA lesions have been treated endovascularly applied for the same reasons.8,12–14 Although there are recent publications concerning endovascular treatment, no precise information is available in the literature regarding the management of ruptured distal PICA aneurysm specifying an endovascular technique. In an effort to provide effective treatment options for patients with a high-risk distal PICA aneurysm, we retrospectively analyzed 11 consecutive patients harboring a ruptured distal PICA aneurysm chosen for endovascular treatment. The aim of this study was to report the clinical outcome and obliteration rate in patients who underwent endovascular treatment for ruptured distal PICA aneurysm, and, by extension, to evaluate the appropriateness of its usefulness as a treatment modality.
Patients and Methods A total of 690 aneurysms were treated with surgery or endovascular treatment from January 2007 to December 2011 at Kyung Hee University Hospital at Gangdong, Seoul, South Korea. Among 690 aneurysms, 84 aneurysms (12.2%) were vertebrobasilar aneurysms. Of these 84 aneurysms, 56 (66.7%) were ruptured and, of these, 11 aneurysms were distal PICA aneurysms. We reviewed the data for these 11 consecutive patients who were followed for at least 1 year until December 2012. Clinical profile, radiologic features, intraprocedural findings, and outcomes were analyzed from patients’ medical records and neuroimaging data. Initial neurologic status before treatment was determined using the Hunt and Hess grading system. On admission, all patients underwent routine laboratory tests with a neurologic examination. Brain computerized tomography (CT) with contrast-enhanced threedimensional CT angiography (3D-CTA) was performed for evaluating initial brain status and the assessment of cerebral vasculature anomalies. Once subarachnoid hemorrhage was diagnosed, conventional angiography of both carotid arteries and vertebral arteries were performed for exact cerebral angio-architecture assessment. The location of PICA aneurysms was determined using the criteria of Lister et al.15 Lister Journal of Neurological Surgery—Part A
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Lee et al. divided the distal PICA into five segments: the anteriormedullary (AM) segment, lateral-medullary (LM) segment, tonsillomedullary (TM) segment, telovelotonsillar (TVT) segment, and cortical (C) segment. Endovascular therapy was primarily used as the preferred treatment method if surgical difficulties were anticipated during microscopic manipulation of major deep neurovascular structures. The radiologic completeness of aneurysm obliteration was assessed as follows: complete, no contrast material filling the aneurysmal sac; residual neck, residual contrast material filling the aneurysmal neck; and residual aneurysm, residual contrast material filling the aneurysmal sac. Clinical outcomes were categorized according to the Glasgow Outcome Scale (GOS) at the time of discharge. Angiographic follow-up (magnetic resonance angiography or conventional angiography) was scheduled at 6 months, 1 year, 2 years, and 5 years after treatment.
Results The mean age at the time of treatment was 56.3 years (range: 30–86 years). The 11 patients consisted of 8 women (72.7%) and 3 men (27.3%). After treatment, the mean follow-up duration was 3.0 years (range: 1–5.5 years). Detailed patient and aneurysmal information is listed in ►Table 1. The incidence of distal PICA aneurysm in our series was 1.7% of all intracranial aneurysms and 14.3% of vertebrobasilar system aneurysms. Ruptured distal PICA aneurysm comprised 2.8% of the total 387 ruptured aneurysms and 19.6% of ruptured vertebrobasilar aneurysms. At presentation to the emergency department, five patients had Hunt and Hess grade 2, two patients had Hunt and Hess grade 3, three patients had grade 4, and one patient had grade 5. Intraventricular hemorrhage was present on initial brain CT at admission in six patients and intracerebellar hemorrhage was found in three patients. Two patients had hydrocephalus. On CTA and cerebral angiography analysis, six patients had saccular aneurysms and five exhibited dissecting aneurysms. The aneurysms were located at LM (n ¼ 5), TVT (n ¼ 4), and TM (n ¼ 2). The mean maximal diameter of the aneurysmal was 6.5 3.1 mm (range: 3.4–12.7mm). Of 11 aneurysms, 6 were treated with pure aneurysm coiling, 4 with coil trapping, and the remaining case was treated with stent-assisted coiling. According to imaging obtained immediately after initial treatment, complete obliteration of the aneurysm was achieved in nine patients (pure coiling: five, coil trapping: three, stent-assisted coiling: one), and a residual neck was found in two patients (pure coiling: two). There was no residual aneurysm filled with contrast after treatment. Good outcomes (GOS of 4 or 5) were achieved in nine patients (pure coiling: five, coil trapping: four), GOS 3 was recorded in one patient (stent assisted coiling), one patient (pure coiling) had a GOS of 1. Patient 8 underwent emergent external ventricular drain insertion for relieving hydrocephalus following subarachnoid hemorrhage (SAH) and intraventricular hemorrhage. No
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344
F/74
M/40
F/86
6
7
8
SAH, IVH
SAH, IVH
SAH, ICbH
SAH, IVH, hydrocephalus
SAH, ICbH
SAH, IVH
SAH, ICbH
SAH
SAH, IVH
SAH, IVH
SAH, hydrocephalus
Presentation
4
2
2
4
5
4
2
3
2
2
3
H-H grade
4
2
2
4
4
4
3
3
4
4
3
Fisher grade
Dissecting
Dissecting
Saccular
Dissecting
Saccular
Saccular
Dissecting
Saccular
Saccular
Saccular
Dissecting
Pathologic type
TVT
TVT
LM
TM
TM
LM
TVT
TVT
LM
LM
LM
Location
6.2
4.7
6.3
3.8
12.3
5.1
12.7
5.5
3.4
5.3
6.7
Maximum diameter, mm
Coil trapping
Coil trapping
Coiling
Stent-assisted coil
Coiling
Coiling
Coil trapping
Coiling
Coiling
Coiling
Coil trapping
Treatment
Complete
Complete
Complete
Complete
Residual neck
Residual neck
Complete
Complete
Complete
Complete
Complete
Radiologic outcome
4
5
5
3
1
5
5
5
5
5
5
GOS
Minor CBLL infarct
Minor CBLL infarct
Death
Complications
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Recanalized in 6-mo follow-up
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Follow-up result
Journal of Neurological Surgery—Part A
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Abbreviations: CBLL, cerebellum; GOS, Glasgow Outcome Scale; H-H, Hunt and Hess classification; ICbH, intracerebellar hemorrhage; IVH, intraventricular hemorrhage; LM, lateral medullary segment; SAH, subarachnoid hemorrhage; TM, tonsillomedullary segment; TVT, telovelotonsillar segment.
F/65
F/54
5
11
F/52
4
M/73
F/30
3
M/38
F/50
2
10
F/57
1
9
Sex/Age, y
Patient no.
Table 1 Summary of 11 patients with ruptured distal posterior inferior cerebellar artery aneurysms treated with endovascular therapy
Endovascular Treatment of Ruptured Distal PICA Aneurysm
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Endovascular Treatment of Ruptured Distal PICA Aneurysm
Lee et al.
Fig. 1 A 74-year-old woman presenting with decreased consciousness. (A) Brain computed tomography (CT) scan showing thick subarachnoid clots more on the left cerebellomedullary cistern. (B) Three-dimensional (3D) CT angiogram revealing an aneurysm of the left distal posterior inferior cerebellar artery (PICA). (C) Vertebral angiogram anteroposterior (AP) image and (D) enlarged reconstructed image of rotational 3D angiogram showing a peripheral aneurysm of the lateral medullary segment of left PICA. (E) Vertebral angiogram road map AP image during intervention depicting coil embolization of the ruptured left distal PICA aneurysm through the contralateral vertebral artery (VA) due to the severe tortuosity of the left VA origin (not shown here). (F) Post-coiling vertebral angiogram lateral image showing small neck remnant.
patient required decompressive craniectomy and hematoma evacuation for the cerebellar hemorrhage. Three patients experienced trivial complications that were resolved in a certain time. Procedure-related complication occurred in one patient during selective embolization that resulted in thromboembolism. Fortunately, thrombembolism remained without symptoms. Two patients had PICA territory infarctions attributable to vasospasm that occurred during the postprocedure period. Aneurysmal neck growth following coil compaction was found at the 6-month follow-up magnetic resonance imaging (MRI) in one patient (Patient 6) who had had residual neck after initial coiling that required additional coil embolization. One patient in a poor clinical condition (Hunt and Hess grade 5) at admission died during the postprocedural hospital stay.
Illustrative Cases Patient 6 (►Fig. 1) A 74-year-old woman with sudden onset of a severe bursting headache was transferred from another hospital. Prior to transfer, endovascular treatment had been attempted but was unsuccessful due to the tortuosity of the ipsilateral vertebral artery origin. A brain CT scan at admission revealed thick hematoma clots in the subarachnoid space, mainly on Journal of Neurological Surgery—Part A
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the left cerebellomedullary cistern. A 3D-CTA demonstrated an aneurysm on the left distal PICA. A vertebral angiogram showed a saccular aneurysm arising at the lateral medullary segment of the left PICA. On the day of admission, we successfully performed coil embolization through the contralateral vertebral artery (VA). A postcoiling vertebral angiogram revealed complete obliteration of the aneurysmal sac but little contrast in the aneurysmal neck. The patient had an uncomplicated recovery after treatment. She was discharged after receiving routine post-SAH management without any neurologic compromise. At the 6-month follow-up MRI, partial recanalization was noticed, and an additional coil embolization was performed.
Patient 5 (►Fig. 2) A 54-year-old woman complaining of a sudden onset headache and vomiting visited the emergency department. Neurologic examination revealed an alert patient with decreased cerebellar function. Emergency brain CT scan showed an intraparenchymal hematoma in the right cerebellar hemisphere. An enlarged vertebral 3D-CTA revealed an aneurysm of the right distal PICA. Subsequent cerebral angiography demonstrated a multilobulated irregular shaped aneurysm of the telovelotonsillar segment of the right PICA with luminal irregularity suggesting a dissection. She was brought to the
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Lee et al.
Fig. 2 A 54-year-old woman presenting with sudden headache and vomiting. (A) Brain computed tomography (CT) scan showing an intraparenchymal hematoma in the right cerebellum. (B) Enlarged three-dimensional (3D) CT vertebral angiogram revealing an aneurysm of the right distal posterior inferior cerebellar artery (PICA). (C) Vertebral angiogram lateral image and (D) enlarged reconstructed image of rotational 3D vertebral angiogram showing a multilobulated irregular shaped aneurysm of the telovelotonsillar segment of right PICA with luminal irregularity suggesting dissection. (E) Vertebral angiogram lateral image after trapping of the distal segment of PICA including the ruptured aneurysm depicting complete exclusion of aneurysm. (F) Follow-up CT scan 2 weeks after PICA trapping showing resorbtion of cerebellar hematoma with no PICA territory infarction.
intervention room for endovascular treatment later on in the day. To attempt parent-artery trapping, she first underwent a PICA balloon occlusion test for 15 minutes. After verification of sufficient blood flow through the collateral circulation, the aneurysm was filled with coils, and, to avoid further dissection, the distal segment of the PICA was trapped with coils. She recovered uneventfully without further neurologic deterioration, and a follow-up brain CT scan 2 weeks later showed a resolving cerebellar hematoma without PICA territory infarction.
Discussion PICA aneurysms usually develop at the VA-PICA junction.12,16 The reported incidence of VA-PICA aneurysm is 0.5 to 3% of all intracranial aneurysms and 20% of those in the vertebrobasilar system.5,7,9,11 A distal PICA aneurysm was defined by Lewis et al17 as arising from more peripheral PICA segments not including the VA-PICA junction. The incidence of distal PICA aneurysm is much rarer, constituting < 30% of all PICA aneurysms, accounting for 0.5 to 1.7% of all intracranial aneurysms.1,4,17,18 Our results did not differ significantly from previous reports, with 1.7% of all intracranial aneurysms and 14.3% of vertebrobasilar system aneurysms classified as PICA aneurysms. The reported mean age of patients who present with distal PICA aneurysm is the fifth and sixth decades of life, generally
younger than that of patients with aneurysms at other locations.1,17,19,20 However, the mean age of our series is 56.3 years, which is somewhat higher than that given in previous reports and similar to aneurysms located in vascular anatomy other than the PICA. This difference could result from the fact that we excluded unruptured incidental aneurysms that were included in previous reports. As described earlier, the PICA segments were classified by Lister et al as AM, LM, TM, TVT, and C, which arise peripherally along the vessel without any association with VA.5,17 A review by Lewis et al reported that in distal PICA aneurysms, telovelotonsillar (36.5%), cortical (25.6%), lateral medullary (19.9%), and tonsillomedullary segments (18.0%) were the most common.17 In our study, distal PICA aneurysm arose most frequently at the lateral medullary and telovelotonsillar segments that were not associated with branching sites of PICA. The anatomic characteristics in two curves and hairpin turns of the distal PICA structure were likely to cause excessive hemodynamic stress on the vessel wall, contributing to elastic lamina injury and subsequent aneurysm formation.1,8 In the present study, 5 of 11 consecutive patients had been diagnosed with a bleed secondary to dissection. Although there should be classic angiographic features such as the pearl and string sign, a double lumen, linear defects, or focal outpouching in a typical dissection,17 it is difficult to demonstrate these findings in small vessels like the distal PICA. Instead, we identified dissecting aneurysmal rupture by Journal of Neurological Surgery—Part A
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Endovascular Treatment of Ruptured Distal PICA Aneurysm
Endovascular Treatment of Ruptured Distal PICA Aneurysm noting solitary or multiple irregular fusiform dilatations with or without narrowing along the associated PICA in angiography and if the SAH was thicker around the corresponding PICA segment on CT scan. The incidence of dissection in PICA aneurysms ranged between 3.4% and 58.3%.1,8,17,19–22 In this report, 5 (45.5%) of 11 aneurysms were dissecting aneurysms, which is on the high end of what is reported in the literature. This appears to be due to the high risk of rupture if dissection occurs in the distal PICA because we only included ruptured aneurysms. In our series, all treatment of ruptured distal PICA aneurysms was performed urgently due to the high incidence of rebleeding, which is established in the literature.8,23,24 Furthermore, small peripheral aneurysms arising on the cerebellar artery are known to be more prone to hemorrhage.25 There are two major points of consensus in clinical practice when treating distal PICA aneurysms endovascularly. First, if the aneurysm is saccular, perform endosaccular coiling with preservation of the PICA lumen, especially if the lesion is in the anterior or lateral medullary segment. As previously demonstrated by Lewis et al,17 most brainstem perforating vessels arise from proximal (anterior or lateral medullary) segments. However, endosaccular coiling with preservation of the PICA lumen may not always be feasible due to specific anatomic variations in the PICA (small caliber, tortuosity, and angulation).3 Second, if dissection is suspected as the source of bleeding, parent artery occlusion is a treatment of choice. Bleeding from dissection occurs as a consequence of internal elastic lamina tearing, further penetrating into the tunica media and adventitia. Therefore, leaving the initial internal elastic lamina untreated will result in recanalization and rebleeding. Fortunately, most dissections occur in the distal segment that generally lacks brainstem perforating vessels. As for expected morbidity in PICA trapping, Chalouhi et al3 stated that trapping of the PICA causes only minimal morbidity, and infarction after PICA occlusion did not resulted in permanent morbidity because infarction occurs only in the cerebellumsparing brainstem. They also mentioned that because perforating arteries form an anastomotic plexiform network at the surface of the medulla that is exclusively supplied by the anterior spinal artery and direct branches of the vertebral arteries, the risk of brainstem ischemia with PICA occlusion is low. According to the present study, four patients underwent PICA trapping by means of coil occlusion for the dissecting aneurysm. Among the four patients, two patients experienced trivial cerebellar infarction following the procedure, of which symptoms were well tolerated and transient. Although endovascular treatment as a primary modality for aneurysmal treatment is becoming more common than surgical treatment, some technical difficulties in the endovascular treatment of distal PICA aneurysms remain. Because the distal PICA is narrow, tortuous, and angulated, superselective catheterization is not often possible, and it is hard to use remodeling techniques such as temporary balloon inflation or stent deployment. Thus far, in treating patients with distal PICA aneurysms, unless remodeling techniques are feasible, the only option is to occlude the aneurysm along with the PICA. Journal of Neurological Surgery—Part A
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Lee et al. Despite the challenging anatomical conditions of the distal PICA, our endovascular technical results are favorable compared with previous series. The reported intraprocedural rupture rate was known to be 4.2 to 19% in the literature.3,7,26 In this series, no intraprocedural rupture occurred. Endovascular approaches tailored to specific patient and aneurysm characteristics may prevent intraprocedural ruptures. In the urgent treatment of ruptured distal PICA aneurysm, the most effective endovascular treatment at present is either endosaccular coiling or parent artery occlusion with coil trapping to prevent rebleeding. Occlusion of the parent artery (after ensuring adequate collateral circulation) is necessary if hemorrhage occurs secondary to a dissecting distal segment PICA aneurysm and remodeling techniques are inapplicable. Future advances such as softer microcatheters and stent material will allow aneurysms to be obliterated with parent artery preservation. Nevertheless, a tailored treatment plan for each aneurysm should be based on these fundamental principles.
Conclusion We report the results of endovascular treatment in the largest series of ruptured distal PICA aneurysms to date. The profiles of endovascular treatment for posterior circulation aneurysms are well documented, but there is still a lack of consensus regarding appropriate treatment strategies for ruptured peripheral cerebellar artery aneurysms. However, the present data suggest that endovascular treatment for ruptured distal PICA aneurysms is a safe and effective treatment modality. More clinical experience with endovascular equipment and future advances are certain to improve the treatment outcomes in patients with distal PICA aneurysms.
References 1 Horiuchi T, Tanaka Y, Hongo K, Nitta J, Kusano Y, Kobayashi S.
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Characteristics of distal posteroinferior cerebellar artery aneurysms. Neurosurgery 2003;53(3):589–595; discussion 595–596 Matsushima T, Matsukado K, Natori Y, Inamura T, Hitotsumatsu T, Fukui M. Surgery on a saccular vertebral artery-posterior inferior cerebellar artery aneurysm via the transcondylar fossa (supracondylar transjugular tubercle) approach or the transcondylar approach: surgical results and indications for using two different lateral skull base approaches. J Neurosurg 2001; 95(2):268–274 Chalouhi N, Jabbour P, Starke RM, et al. Endovascular treatment of proximal and distal posterior inferior cerebellar artery aneurysms. J Neurosurg 2013;118(5):991–999 Locksley HB. Natural history of subarachnoid hemorrhage, intracranial aneurysms and arteriovenous malformations. Based on 6368 cases in the cooperative study. J Neurosurg 1966;25(2): 219–239 Hudgins RJ, Day AL, Quisling RG, Rhoton AL Jr, Sypert GW, GarciaBengochea F. Aneurysms of the posterior inferior cerebellar artery. A clinical and anatomical analysis. J Neurosurg 1983;58(3): 381–387 Ishikawa T, Suzuki A, Yasui N. Distal posterior inferior cerebellar aneurysms—report of 12 cases. Neurol Med Chir (Tokyo) 1990; 30(2):100–108
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Posterior inferior cerebellar artery aneurysms: incidence, clinical presentation, and outcome of endovascular treatment. AJNR Am J Neuroradiol 2008;29(1):86–90 Isokangas JM, Siniluoto T, Tikkakoski T, Kumpulainen T. Endovascular treatment of peripheral aneurysms of the posterior inferior cerebellar artery. AJNR Am J Neuroradiol 2008;29(9):1783–1788 Harati A, Mpotsaris A, Lohmann F, et al. Strategies in the treatment of distal cerebellar aneurysms: report of a series of 11 patients. J Neurol Surg A Cent Eur Neurosurg 2012;73(5):267–274 Salcman M, Rigamonti D, Numaguchi Y, Sadato N. Aneurysms of the posterior inferior cerebellar artery-vertebral artery complex: variations on a theme. Neurosurgery 1990;27(1):12–20; discussion 20–21 Al-khayat H, Al-Khayat H, Beshay J, Manner D, White J. Vertebral artery-posteroinferior cerebellar artery aneurysms: clinical and lower cranial nerve outcomes in 52 patients. Neurosurgery 2005; 56(1):2–10; discussion 11 Jeon SG, Kwon H, Ahn JS, Kwun BD, Choi CG, Jin SC. Detachable coil embolization for saccular posterior inferior cerebellar artery aneurysms. J Korean Neurosurg Soc 2009;46(3):221–225 Dowd CF, Halbach VV, Higashida RT, Barnwell SL, Hieshima GB. Endovascular coil embolization of unusual posterior inferior cerebellar artery aneurysms. Neurosurgery 1990;27(6):954–961 Lubicz B, Leclerc X, Gauvrit JY, Lejeune JP, Pruvo JP. Endovascular treatment of peripheral cerebellar artery aneurysms. AJNR Am J Neuroradiol 2003;24(6):1208–1213 Lister JR, Rhoton AL Jr, Matsushima T, Peace DA. Microsurgical anatomy of the posterior inferior cerebellar artery. Neurosurgery 1982;10(2):170–199 Mericle RA, Reig AS, Burry MV, Eskioglu E, Firment CS, Santra S. Endovascular surgery for proximal posterior inferior cerebellar artery aneurysms: an analysis of Glasgow Outcome Score by Hunt-
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Hess grades. Neurosurgery 2006;58(4):619–625; discussion 619– 625 Lewis SB, Chang DJ, Peace DA, Lafrentz PJ, Day AL. Distal posterior inferior cerebellar artery aneurysms: clinical features and management. J Neurosurg 2002;97(4):756–766 Zingale A, Chiaramonte I, Consoli V, Albanese V. Distal posterior inferior cerebellar artery saccular and giant aneurysms: report of two new cases and a comprehensive review of the surgicallytreated cases. J Neurosurg Sci 1994;38(2):93–104 Park JS, Lee TH, Seo EK, Cho YJ. Aneurysms of distal posterior inferior cerebellar artery. J Korean Neurosurg Soc 2008;44(4): 205–210 Tokimura H, Yamahata H, Kamezawa T, et al. Clinical presentation and treatment of distal posterior inferior cerebellar artery aneurysms. Neurosurg Rev 2011;34(1):57–67 Wu J, Xu F, Yu ZQ, et al. Clinical experiences of ruptured posteroinferior cerebellar artery aneurysms and anatomical analysis in the cadaver in a single center of China. Clin Neurol Neurosurg 2012;114(4):366–371 Kleinpeter G. Why are aneurysms of the posterior inferior cerebellar artery so unique? Clinical experience and review of the literature. Minim Invasive Neurosurg 2004;47(2):93–101 Yamaura A. Diagnosis and treatment of vertebral aneurysms. J Neurosurg 1988;69(3):345–349 Tawk RG, Bendok BR, Qureshi AI, et al. Isolated dissections and dissecting aneurysms of the posterior inferior cerebellar artery: topic and literature review. Neurosurg Rev 2003;26(3):180–187 Gács G, Viñuela F, Fox AJ, Drake CG. Peripheral aneurysms of the cerebellar arteries. Review of 16 cases. J Neurosurg 1983;58(1): 63–68 Bradac GB, Bergui M. Endovascular treatment of the posterior inferior cerebellar artery aneurysms. Neuroradiology 2004; 46(12):1006–1011
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Endovascular Treatment of Ruptured Distal PICA Aneurysm
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Endovascular Treatment of Ruptured Distal Posterior Inferior Cerebellar Artery Aneurysm. Report of Two Exemplary Cases and Retrospective Analysis of 11 Cases Seung Hwan Lee1
Jun Seok Koh1
1 Department of Neurosurgery, Kyung Hee University Hospital at
Gangdong, College of Medicine, Kyung Hee University, Seoul, Republic of Korea
Address for correspondence Seung Hwan Lee, MD, PhD, Department of Neurosurgery, Kyung Hee University Hospital at Gangdong, College of Medicine, Kyung Hee University, 134-090, Sangil-Dong 149, Gangdong-Gu Seoul, Republic of Korea (e-mail: [email protected]).
J Neurol Surg A 2014;75:343–349.
Abstract
Keywords
► distal PICA aneurysm ► endovascular treatment ► subarachnoid hemorrhage
received October 29, 2013 accepted after revision February 11, 2014 published online May 12, 2014
Background and Purpose Although endovascular therapy for intracranial aneurysms has recently started to replace surgical treatment and literature regarding endovascular therapy’s advantages and disadvantages is being published, literature concerning the endovascular treatment of distal posterior inferior cerebellar artery (PICA) aneurysms specifically limited to rupture are lacking. We describe the clinical characteristics of ruptured distal PICA aneurysms, their clinical outcomes, and the strategies in which endovascular treatment are used. Patients and Methods Eleven consecutive patients with ruptured distal PICA aneurysm with at least 1 year of follow-up were retrospectively reviewed. Clinical profiles and radiologic and interventional methods were analyzed. Results The mean age at the time of treatment was 56.3 years (range: 30–86 years). The 11 patients consisted of 8 women (72.7%) and 3 men (27.3%). Six patients had a saccular aneurysm; 5 had a dissecting aneurysm. The aneurysms were located at the lateral medullary segment (n ¼ 5), telovelotonsillar segment (n ¼ 4), and tonsillomedullary segment (n ¼ 2). The mean maximal aneurysm diameter was 6.5 3.1 mm (range: 3.4–12.7 mm). Of the 11 aneurysms, 6 were treated with pure aneurysm coiling, 4 were treated with coil trapping, and 1 was treated with stent-assisted coiling. Complete aneurysm obliteration was achieved in nine patients (pure coiling: five, coil trapping: three, stent-assisted coiling: one), and a residual neck was found in two patients (pure coiling: two). Good outcomes (Glasgow Outcome Scale [GOS] of 4 or 5) were achieved in nine patients (pure coiling: five, coil trapping: four), a GOS of 3 was recorded in one patient (stent-assisted coiling), and one patient (pure coiling) had a GOS of 1. Conclusion The present data suggest that endovascular treatment for ruptured distal PICA aneurysms is a safe and effective treatment modality under an elaborate treatment plan.
© 2014 Georg Thieme Verlag KG Stuttgart · New York
DOI http://dx.doi.org/ 10.1055/s-0034-1373665. ISSN 2193-6315.
This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.
Hee Sup Shin1
Endovascular Treatment of Ruptured Distal PICA Aneurysm
Introduction Aneurysms of the posterior inferior cerebellar artery (PICA) are rare but often lethal due to proximity to the brainstem1,2 and a high rebleeding rate.3 PICA aneurysms account for 0.5 to 3.0% of all intracranial aneurysms,4,5 and their rebleeding rate is reported to be as high as 78%.6 Distal PICA aneurysms are found to constitute only about a fifth of all PICA aneurysms5,7–9 and are associated with a dissection rate as high as 58%.8 Despite recent advancements in microsurgery with highquality optical devices, surgical treatment of these aneurysms is not always successful due to the complex neurovascular structural relationship with the brainstem and low cranial nerves such as IX, X, and XI.1,2,8,10,11 Alternatively, endovascular treatment is becoming more frequently used in the treatment of surgically inaccessible or difficult lesions; distal PICA lesions have been treated endovascularly applied for the same reasons.8,12–14 Although there are recent publications concerning endovascular treatment, no precise information is available in the literature regarding the management of ruptured distal PICA aneurysm specifying an endovascular technique. In an effort to provide effective treatment options for patients with a high-risk distal PICA aneurysm, we retrospectively analyzed 11 consecutive patients harboring a ruptured distal PICA aneurysm chosen for endovascular treatment. The aim of this study was to report the clinical outcome and obliteration rate in patients who underwent endovascular treatment for ruptured distal PICA aneurysm, and, by extension, to evaluate the appropriateness of its usefulness as a treatment modality.
Patients and Methods A total of 690 aneurysms were treated with surgery or endovascular treatment from January 2007 to December 2011 at Kyung Hee University Hospital at Gangdong, Seoul, South Korea. Among 690 aneurysms, 84 aneurysms (12.2%) were vertebrobasilar aneurysms. Of these 84 aneurysms, 56 (66.7%) were ruptured and, of these, 11 aneurysms were distal PICA aneurysms. We reviewed the data for these 11 consecutive patients who were followed for at least 1 year until December 2012. Clinical profile, radiologic features, intraprocedural findings, and outcomes were analyzed from patients’ medical records and neuroimaging data. Initial neurologic status before treatment was determined using the Hunt and Hess grading system. On admission, all patients underwent routine laboratory tests with a neurologic examination. Brain computerized tomography (CT) with contrast-enhanced threedimensional CT angiography (3D-CTA) was performed for evaluating initial brain status and the assessment of cerebral vasculature anomalies. Once subarachnoid hemorrhage was diagnosed, conventional angiography of both carotid arteries and vertebral arteries were performed for exact cerebral angio-architecture assessment. The location of PICA aneurysms was determined using the criteria of Lister et al.15 Lister Journal of Neurological Surgery—Part A
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Lee et al. divided the distal PICA into five segments: the anteriormedullary (AM) segment, lateral-medullary (LM) segment, tonsillomedullary (TM) segment, telovelotonsillar (TVT) segment, and cortical (C) segment. Endovascular therapy was primarily used as the preferred treatment method if surgical difficulties were anticipated during microscopic manipulation of major deep neurovascular structures. The radiologic completeness of aneurysm obliteration was assessed as follows: complete, no contrast material filling the aneurysmal sac; residual neck, residual contrast material filling the aneurysmal neck; and residual aneurysm, residual contrast material filling the aneurysmal sac. Clinical outcomes were categorized according to the Glasgow Outcome Scale (GOS) at the time of discharge. Angiographic follow-up (magnetic resonance angiography or conventional angiography) was scheduled at 6 months, 1 year, 2 years, and 5 years after treatment.
Results The mean age at the time of treatment was 56.3 years (range: 30–86 years). The 11 patients consisted of 8 women (72.7%) and 3 men (27.3%). After treatment, the mean follow-up duration was 3.0 years (range: 1–5.5 years). Detailed patient and aneurysmal information is listed in ►Table 1. The incidence of distal PICA aneurysm in our series was 1.7% of all intracranial aneurysms and 14.3% of vertebrobasilar system aneurysms. Ruptured distal PICA aneurysm comprised 2.8% of the total 387 ruptured aneurysms and 19.6% of ruptured vertebrobasilar aneurysms. At presentation to the emergency department, five patients had Hunt and Hess grade 2, two patients had Hunt and Hess grade 3, three patients had grade 4, and one patient had grade 5. Intraventricular hemorrhage was present on initial brain CT at admission in six patients and intracerebellar hemorrhage was found in three patients. Two patients had hydrocephalus. On CTA and cerebral angiography analysis, six patients had saccular aneurysms and five exhibited dissecting aneurysms. The aneurysms were located at LM (n ¼ 5), TVT (n ¼ 4), and TM (n ¼ 2). The mean maximal diameter of the aneurysmal was 6.5 3.1 mm (range: 3.4–12.7mm). Of 11 aneurysms, 6 were treated with pure aneurysm coiling, 4 with coil trapping, and the remaining case was treated with stent-assisted coiling. According to imaging obtained immediately after initial treatment, complete obliteration of the aneurysm was achieved in nine patients (pure coiling: five, coil trapping: three, stent-assisted coiling: one), and a residual neck was found in two patients (pure coiling: two). There was no residual aneurysm filled with contrast after treatment. Good outcomes (GOS of 4 or 5) were achieved in nine patients (pure coiling: five, coil trapping: four), GOS 3 was recorded in one patient (stent assisted coiling), one patient (pure coiling) had a GOS of 1. Patient 8 underwent emergent external ventricular drain insertion for relieving hydrocephalus following subarachnoid hemorrhage (SAH) and intraventricular hemorrhage. No
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344
F/74
M/40
F/86
6
7
8
SAH, IVH
SAH, IVH
SAH, ICbH
SAH, IVH, hydrocephalus
SAH, ICbH
SAH, IVH
SAH, ICbH
SAH
SAH, IVH
SAH, IVH
SAH, hydrocephalus
Presentation
4
2
2
4
5
4
2
3
2
2
3
H-H grade
4
2
2
4
4
4
3
3
4
4
3
Fisher grade
Dissecting
Dissecting
Saccular
Dissecting
Saccular
Saccular
Dissecting
Saccular
Saccular
Saccular
Dissecting
Pathologic type
TVT
TVT
LM
TM
TM
LM
TVT
TVT
LM
LM
LM
Location
6.2
4.7
6.3
3.8
12.3
5.1
12.7
5.5
3.4
5.3
6.7
Maximum diameter, mm
Coil trapping
Coil trapping
Coiling
Stent-assisted coil
Coiling
Coiling
Coil trapping
Coiling
Coiling
Coiling
Coil trapping
Treatment
Complete
Complete
Complete
Complete
Residual neck
Residual neck
Complete
Complete
Complete
Complete
Complete
Radiologic outcome
4
5
5
3
1
5
5
5
5
5
5
GOS
Minor CBLL infarct
Minor CBLL infarct
Death
Complications
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Recanalized in 6-mo follow-up
Unchanged
Unchanged
Unchanged
Unchanged
Unchanged
Follow-up result
Journal of Neurological Surgery—Part A
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Abbreviations: CBLL, cerebellum; GOS, Glasgow Outcome Scale; H-H, Hunt and Hess classification; ICbH, intracerebellar hemorrhage; IVH, intraventricular hemorrhage; LM, lateral medullary segment; SAH, subarachnoid hemorrhage; TM, tonsillomedullary segment; TVT, telovelotonsillar segment.
F/65
F/54
5
11
F/52
4
M/73
F/30
3
M/38
F/50
2
10
F/57
1
9
Sex/Age, y
Patient no.
Table 1 Summary of 11 patients with ruptured distal posterior inferior cerebellar artery aneurysms treated with endovascular therapy
Endovascular Treatment of Ruptured Distal PICA Aneurysm
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Endovascular Treatment of Ruptured Distal PICA Aneurysm
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Fig. 1 A 74-year-old woman presenting with decreased consciousness. (A) Brain computed tomography (CT) scan showing thick subarachnoid clots more on the left cerebellomedullary cistern. (B) Three-dimensional (3D) CT angiogram revealing an aneurysm of the left distal posterior inferior cerebellar artery (PICA). (C) Vertebral angiogram anteroposterior (AP) image and (D) enlarged reconstructed image of rotational 3D angiogram showing a peripheral aneurysm of the lateral medullary segment of left PICA. (E) Vertebral angiogram road map AP image during intervention depicting coil embolization of the ruptured left distal PICA aneurysm through the contralateral vertebral artery (VA) due to the severe tortuosity of the left VA origin (not shown here). (F) Post-coiling vertebral angiogram lateral image showing small neck remnant.
patient required decompressive craniectomy and hematoma evacuation for the cerebellar hemorrhage. Three patients experienced trivial complications that were resolved in a certain time. Procedure-related complication occurred in one patient during selective embolization that resulted in thromboembolism. Fortunately, thrombembolism remained without symptoms. Two patients had PICA territory infarctions attributable to vasospasm that occurred during the postprocedure period. Aneurysmal neck growth following coil compaction was found at the 6-month follow-up magnetic resonance imaging (MRI) in one patient (Patient 6) who had had residual neck after initial coiling that required additional coil embolization. One patient in a poor clinical condition (Hunt and Hess grade 5) at admission died during the postprocedural hospital stay.
Illustrative Cases Patient 6 (►Fig. 1) A 74-year-old woman with sudden onset of a severe bursting headache was transferred from another hospital. Prior to transfer, endovascular treatment had been attempted but was unsuccessful due to the tortuosity of the ipsilateral vertebral artery origin. A brain CT scan at admission revealed thick hematoma clots in the subarachnoid space, mainly on Journal of Neurological Surgery—Part A
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the left cerebellomedullary cistern. A 3D-CTA demonstrated an aneurysm on the left distal PICA. A vertebral angiogram showed a saccular aneurysm arising at the lateral medullary segment of the left PICA. On the day of admission, we successfully performed coil embolization through the contralateral vertebral artery (VA). A postcoiling vertebral angiogram revealed complete obliteration of the aneurysmal sac but little contrast in the aneurysmal neck. The patient had an uncomplicated recovery after treatment. She was discharged after receiving routine post-SAH management without any neurologic compromise. At the 6-month follow-up MRI, partial recanalization was noticed, and an additional coil embolization was performed.
Patient 5 (►Fig. 2) A 54-year-old woman complaining of a sudden onset headache and vomiting visited the emergency department. Neurologic examination revealed an alert patient with decreased cerebellar function. Emergency brain CT scan showed an intraparenchymal hematoma in the right cerebellar hemisphere. An enlarged vertebral 3D-CTA revealed an aneurysm of the right distal PICA. Subsequent cerebral angiography demonstrated a multilobulated irregular shaped aneurysm of the telovelotonsillar segment of the right PICA with luminal irregularity suggesting a dissection. She was brought to the
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Fig. 2 A 54-year-old woman presenting with sudden headache and vomiting. (A) Brain computed tomography (CT) scan showing an intraparenchymal hematoma in the right cerebellum. (B) Enlarged three-dimensional (3D) CT vertebral angiogram revealing an aneurysm of the right distal posterior inferior cerebellar artery (PICA). (C) Vertebral angiogram lateral image and (D) enlarged reconstructed image of rotational 3D vertebral angiogram showing a multilobulated irregular shaped aneurysm of the telovelotonsillar segment of right PICA with luminal irregularity suggesting dissection. (E) Vertebral angiogram lateral image after trapping of the distal segment of PICA including the ruptured aneurysm depicting complete exclusion of aneurysm. (F) Follow-up CT scan 2 weeks after PICA trapping showing resorbtion of cerebellar hematoma with no PICA territory infarction.
intervention room for endovascular treatment later on in the day. To attempt parent-artery trapping, she first underwent a PICA balloon occlusion test for 15 minutes. After verification of sufficient blood flow through the collateral circulation, the aneurysm was filled with coils, and, to avoid further dissection, the distal segment of the PICA was trapped with coils. She recovered uneventfully without further neurologic deterioration, and a follow-up brain CT scan 2 weeks later showed a resolving cerebellar hematoma without PICA territory infarction.
Discussion PICA aneurysms usually develop at the VA-PICA junction.12,16 The reported incidence of VA-PICA aneurysm is 0.5 to 3% of all intracranial aneurysms and 20% of those in the vertebrobasilar system.5,7,9,11 A distal PICA aneurysm was defined by Lewis et al17 as arising from more peripheral PICA segments not including the VA-PICA junction. The incidence of distal PICA aneurysm is much rarer, constituting < 30% of all PICA aneurysms, accounting for 0.5 to 1.7% of all intracranial aneurysms.1,4,17,18 Our results did not differ significantly from previous reports, with 1.7% of all intracranial aneurysms and 14.3% of vertebrobasilar system aneurysms classified as PICA aneurysms. The reported mean age of patients who present with distal PICA aneurysm is the fifth and sixth decades of life, generally
younger than that of patients with aneurysms at other locations.1,17,19,20 However, the mean age of our series is 56.3 years, which is somewhat higher than that given in previous reports and similar to aneurysms located in vascular anatomy other than the PICA. This difference could result from the fact that we excluded unruptured incidental aneurysms that were included in previous reports. As described earlier, the PICA segments were classified by Lister et al as AM, LM, TM, TVT, and C, which arise peripherally along the vessel without any association with VA.5,17 A review by Lewis et al reported that in distal PICA aneurysms, telovelotonsillar (36.5%), cortical (25.6%), lateral medullary (19.9%), and tonsillomedullary segments (18.0%) were the most common.17 In our study, distal PICA aneurysm arose most frequently at the lateral medullary and telovelotonsillar segments that were not associated with branching sites of PICA. The anatomic characteristics in two curves and hairpin turns of the distal PICA structure were likely to cause excessive hemodynamic stress on the vessel wall, contributing to elastic lamina injury and subsequent aneurysm formation.1,8 In the present study, 5 of 11 consecutive patients had been diagnosed with a bleed secondary to dissection. Although there should be classic angiographic features such as the pearl and string sign, a double lumen, linear defects, or focal outpouching in a typical dissection,17 it is difficult to demonstrate these findings in small vessels like the distal PICA. Instead, we identified dissecting aneurysmal rupture by Journal of Neurological Surgery—Part A
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Endovascular Treatment of Ruptured Distal PICA Aneurysm
Endovascular Treatment of Ruptured Distal PICA Aneurysm noting solitary or multiple irregular fusiform dilatations with or without narrowing along the associated PICA in angiography and if the SAH was thicker around the corresponding PICA segment on CT scan. The incidence of dissection in PICA aneurysms ranged between 3.4% and 58.3%.1,8,17,19–22 In this report, 5 (45.5%) of 11 aneurysms were dissecting aneurysms, which is on the high end of what is reported in the literature. This appears to be due to the high risk of rupture if dissection occurs in the distal PICA because we only included ruptured aneurysms. In our series, all treatment of ruptured distal PICA aneurysms was performed urgently due to the high incidence of rebleeding, which is established in the literature.8,23,24 Furthermore, small peripheral aneurysms arising on the cerebellar artery are known to be more prone to hemorrhage.25 There are two major points of consensus in clinical practice when treating distal PICA aneurysms endovascularly. First, if the aneurysm is saccular, perform endosaccular coiling with preservation of the PICA lumen, especially if the lesion is in the anterior or lateral medullary segment. As previously demonstrated by Lewis et al,17 most brainstem perforating vessels arise from proximal (anterior or lateral medullary) segments. However, endosaccular coiling with preservation of the PICA lumen may not always be feasible due to specific anatomic variations in the PICA (small caliber, tortuosity, and angulation).3 Second, if dissection is suspected as the source of bleeding, parent artery occlusion is a treatment of choice. Bleeding from dissection occurs as a consequence of internal elastic lamina tearing, further penetrating into the tunica media and adventitia. Therefore, leaving the initial internal elastic lamina untreated will result in recanalization and rebleeding. Fortunately, most dissections occur in the distal segment that generally lacks brainstem perforating vessels. As for expected morbidity in PICA trapping, Chalouhi et al3 stated that trapping of the PICA causes only minimal morbidity, and infarction after PICA occlusion did not resulted in permanent morbidity because infarction occurs only in the cerebellumsparing brainstem. They also mentioned that because perforating arteries form an anastomotic plexiform network at the surface of the medulla that is exclusively supplied by the anterior spinal artery and direct branches of the vertebral arteries, the risk of brainstem ischemia with PICA occlusion is low. According to the present study, four patients underwent PICA trapping by means of coil occlusion for the dissecting aneurysm. Among the four patients, two patients experienced trivial cerebellar infarction following the procedure, of which symptoms were well tolerated and transient. Although endovascular treatment as a primary modality for aneurysmal treatment is becoming more common than surgical treatment, some technical difficulties in the endovascular treatment of distal PICA aneurysms remain. Because the distal PICA is narrow, tortuous, and angulated, superselective catheterization is not often possible, and it is hard to use remodeling techniques such as temporary balloon inflation or stent deployment. Thus far, in treating patients with distal PICA aneurysms, unless remodeling techniques are feasible, the only option is to occlude the aneurysm along with the PICA. Journal of Neurological Surgery—Part A
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Lee et al. Despite the challenging anatomical conditions of the distal PICA, our endovascular technical results are favorable compared with previous series. The reported intraprocedural rupture rate was known to be 4.2 to 19% in the literature.3,7,26 In this series, no intraprocedural rupture occurred. Endovascular approaches tailored to specific patient and aneurysm characteristics may prevent intraprocedural ruptures. In the urgent treatment of ruptured distal PICA aneurysm, the most effective endovascular treatment at present is either endosaccular coiling or parent artery occlusion with coil trapping to prevent rebleeding. Occlusion of the parent artery (after ensuring adequate collateral circulation) is necessary if hemorrhage occurs secondary to a dissecting distal segment PICA aneurysm and remodeling techniques are inapplicable. Future advances such as softer microcatheters and stent material will allow aneurysms to be obliterated with parent artery preservation. Nevertheless, a tailored treatment plan for each aneurysm should be based on these fundamental principles.
Conclusion We report the results of endovascular treatment in the largest series of ruptured distal PICA aneurysms to date. The profiles of endovascular treatment for posterior circulation aneurysms are well documented, but there is still a lack of consensus regarding appropriate treatment strategies for ruptured peripheral cerebellar artery aneurysms. However, the present data suggest that endovascular treatment for ruptured distal PICA aneurysms is a safe and effective treatment modality. More clinical experience with endovascular equipment and future advances are certain to improve the treatment outcomes in patients with distal PICA aneurysms.
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Endovascular Treatment of Ruptured Distal PICA Aneurysm
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