British Journal of Neurosurgery
ISSN: 0268-8697 (Print) 1360-046X (Online) Journal homepage: http://www.tandfonline.com/loi/ibjn20
Vertebrobasilar junction giant aneurysm: Lessons learned from a neurosurgical audit and anatomical investigation Francesca Graziano, Mario Ganau, Vittorio Maria Russo, Domenico G. Iacopino & Arthur John Ulm III To cite this article: Francesca Graziano, Mario Ganau, Vittorio Maria Russo, Domenico G. Iacopino & Arthur John Ulm III (2015): Vertebrobasilar junction giant aneurysm: Lessons learned from a neurosurgical audit and anatomical investigation, British Journal of Neurosurgery, DOI: 10.3109/02688697.2015.1023778 To link to this article: http://dx.doi.org/10.3109/02688697.2015.1023778
Published online: 20 Apr 2015.
Submit your article to this journal
Article views: 21
View related articles
View Crossmark data
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ibjn20 Download by: [University of Sherbrooke]
Date: 03 November 2015, At: 02:25
British Journal of Neurosurgery, 2015; Early Online: 1–5 © 2015 The Neurosurgical Foundation ISSN: 0268-8697 print / ISSN 1360-046X online DOI: 10.3109/02688697.2015.1023778
Education Report
Vertebrobasilar junction giant aneurysm: Lessons learned from a neurosurgical audit and anatomical investigation Francesca Graziano1,2, Mario Ganau1, Vittorio Maria Russo1, Domenico G. Iacopino2 & Arthur John Ulm III1 1Department of Neurosurgery, Louisiana State University, New Orleans, Louisiana, USA and 2Department of Experimental
Downloaded by [University of Sherbrooke] at 02:25 03 November 2015
Biomedicine and Clinical Neurosciences, Neurosurgical Clinic, AOPU “P. Giaccone” Universita’ degli Studi di Palermo, Italy
laboratory work uphold a great informative value regarding the complex management of those lesions. The related takehome messages are therefore worth sharing with the BJN community of young trainees.
Abstract The treatment of vascular lesions of the vertebrobasilar junction (VBJ) remains a challenging task in the neurosurgical practice and the gold standard therapy is still under debate. In this article, the authors report a detailed postmortem study of a VBJ giant aneurysm (GA) previously endovascularly treated. Although the decision-making process for the vast majority of neurosurgical treatment can nowadays be accurately carried out during the preoperative planning (i.e., with the aid of neuroimaging fusion protocols, neuronavigation platforms, etc.) meant to maximize the anatomical understanding of the lesions and minimize possible intraprocedural challenges, this postmortem study represents the ultimate essence of neurosurgical audit as the laboratory investigations allowed to reevaluate the clinical history of VBJ GA, and reassess the multiple strategies available for its treatment with a straightforward anatomical perspective. Specifically, the lessons learned through this clinical and laboratory work uphold a great educational value regarding the complex management of those lesions, including the possible role of combined skull base surgical approaches.
Case description A 61-year-old woman without significant comorbidities apart from blood pressure (hypertension) was diagnosed with a GA (3.8 cm 3.6 cm) located at the VBJ after neuroradiological investigations for chronic six-month occipital headache and postural instability. The aneurysm was treated by the last author (A.J.U.) through a two-staged embolization procedure. At first, a 4.5 mm 20 mm Neuroform Stent was placed across the neck of the aneurysm and 1 month later, the aneurysm was filled with 11 Guglielmi detachable coils (GDC-18) (Fig. 1). Five months later, the aneurysm recanalized (Fig. 1C). An endovascular treatment of the aneurysm was chosen again (also considering the personal preferences of the patient). As per protocol, clinical balloon test occlusion or BTO was performed. Nevertheless, the patient developed slurred speech and decreased level of consciousness just 5 min after the occlusion of both vertebral arteries (VAs). In the light of this result, the aneurysm was endosaccularly embolized with coils and Onyx (Fig. 1D). In addition, the right non-dominant vertebral artery was occluded below the postero-inferior cerebellar artery (PICA) origin, with Onyx 34. The patient was ultimately discharged to the rehabilitation unit at her neurological baseline. Fourteen months later, the patient died due to a cause unrelated to the aneurysm; upon her husband’s request, her body was donated to the Department of Neurosurgery, Louisiana State University, New Orleans for anatomical dissection and educational training. The description of the thorough neurosurgical audit and microsurgical investigation conducted on this case is given below.
Keywords: anatomical dissection; neurosurgical audit; skull base approaches; vertebrobasilar junction aneurysms
Introduction The treatment of vascular lesions of the vertebrobasilar junction (VBJ) remains a challenging task in the neurosurgical practice and the gold standard therapy is still under debate. In this article, the authors report a detailed postmortem study of a VBJ giant aneurysm (GA) that was previously treated endovascularly and discuss the potential role which would have had a microsurgical approach in exposing and managing the lesion. This study represents the ultimate essence of neurosurgical audit, as the lessons learned through this clinical and
Correspondence: Francesca Graziano, MD, Department of Experimental Biomedicine and Clinical Neurosciences, Neurosurgical Clinic, AOPU “P. Giaccone” Universita’ degli Studi di Palermo, 129, Via del Vespro, 90100 Palermo, Italy. Tel: 39 (393) 5684317. Fax: ( 39) 091 655 2393. E-mail: [email protected] Received for publication 9 June 2014; accepted 22 February 2015
1
2 F. Graziano et al. exposed in order to open the dura as close to the sinus as possible and increasing the surgical view along the cerebellopontine angle (CPA) (Fig. 2C).
Downloaded by [University of Sherbrooke] at 02:25 03 November 2015
Posterior transpetrosal approach with its extensions The posterior transpetrosal approach included various degrees of mastoid and labyrinth resection in order to minimize the neurovascular structures retraction and to provide a surgical view as close as possible to the giant lesion. The first degree of mastoid resection was the retrolabyrinthine extension. It included a complete mastoidectomy, exposing of the bony capsule of the semicircular canals and skeletonizing of the mastoid segment of the facial nerve. In the translabyrinthine extension, the semicircular canals and the vestibule were fully drilled out, and the tympanic, labyrinthine, and meatal segments of the facial nerve were skeletonized. Afterward, the transcochlear extension was performed, the otic capsule was drilled completely, the labyrinthine segment of the facial nerve was transposed posteriorly, and the cochlea and the petrous apex were drilled out (Fig. 2D and E). Fig. 1. A–D. DSA of the vertebrobasilar system. (A) Left Vertebral DSA. The GA at the VBJ presented an almost spherical shape and a large neck, measuring 14 mm. The GA shifted the BA to the right side. The right PICA rose almost at the level of the VBJ. (B) I Endovascular treatment. Left vertebral DSA. As part I of the two-staged procedure, a Neuroform Stent was placed across the aneurysm neck. One month later, the aneurysm was filled with GDC coils. (C–D) Aneurysm recanalization and II Endovascular treatment. After 5 months, the recanalization occurred. Four GDC 18 coils were used to create a scaffold and a total of 5 cc of Onyx 34 and 4 cc of Onyx 18 were injected in the recanalized region.
Laboratory investigation The specimen was embalmed and the arteries and veins were injected with colored silicone. The combination of the following skull base approaches was performed bilaterally: the far-lateral approach (FLA) with its transcondylar and supracondylar extensions; the retrosigmoid, the presigmoid with its retro, translabyrinthine, and transcochlear extensions; and the extended anterior transpetrosal.
Far-lateral approach with its extensions A lateral suboccipital craniotomy was performed, including resection of the posterolateral rim of the foramen magnum, and extending laterally until the medial edge of the sigmoid sinus was exposed. Inferiorly and laterally, the craniotomy was extended over the condylar fossa and condylar canal. The ipsilateral posterior arch of C1 from the sulcus arteriosus to the midline was removed. The transverse foramen of C1 was opened up and the V3 segment of the VA was mobilized and transposed medially. Afterward, the transcondylar extension was carried out. Subsequently, the jugular tubercle was reached and removed extradurally so that a wide exposure with a flat angle along the foramen magnum, lower clivus, and anterolateral brainstem was provided (Fig. 2A and B).
Retrosigmoid approach The posterolateral craniotomy was enlarged until the posterior aspect of the sigmoid transverse sinus junction was
Anterior transpetrosal approach A subtemporal craniotomy, extending down to the floor of the middle fossa, was added to the previous bone work. The dura was elevated from the floor in order to expose, progressively, the middle meningeal artery, the greater superficial petrosal nerve or GSPN, and the mandibular branch of the trigeminal nerve. The medial insertion of the tentorium was then exposed and the posterolateral triangle or Kawase triangle was identified and, in order to access the upper clivus, the shallow volume of petrous apex, in the Kawase triangle, was drilled out (Fig. 2F–I).
Discussion Vascular lesions located at the VBJ are rare and complex pathologies with a dismal natural history.1–4 Even though the high risk of rupture makes their treatment mandatory, the management is extremely challenging and associated with high rate of morbidity and mortality. Several treatment options are currently available, including either surgical or endovascular technique.1,5–15 Different factors may play a critical role in the selection of the most appropriate therapy, surgical or endovascular, including the preoperative clinical and neurological assessment of the patient, the features of the aneurysm and its relationship with surrounding neural, osseous, and vascular structures. The different risk factors for bleeding of unruptured intracranial aneurysms have been described in several studies; noteworthily, a relatively recent paper was focused on univariate and multivariate analyses conducted through a meta-regression study including all the clinical series published during the decade 1996–2006.16 From these analyses several statistically significant risk factors for rupture emerged, some were already known and some others were not officially stated before: age 60 years [risk ratio (RR), 2.0; 95% confidence interval (CI), 1.1–3.7], female gender (RR, 1.6; 95% CI, 1.1–2.4), Japanese or Finnish descent (RR, 3.4; 95% CI, 2.6–4.4), size 5 mm (RR, 2.3; 95% CI, 1.0–5.2),
Downloaded by [University of Sherbrooke] at 02:25 03 November 2015
Vertebrobasilar junction giant aneurysm 3
Fig. 2. Microsurgical exposure. (A) Full-extended (transcondylar and supracondylar) FLA. Left side: The infratonsillar retraction of the cerebellar hemisphere exposed the cisternal segment of the lower CNs from the IX to the XII, running behind the VA. The inferior surface of the aneurysm was visualized. (B) Endoscopic view trough the FLA. Left side: The endoscope was introduced through the surgical corridor gained by the extradural resection of the jugular tubercle, just beside the retracted dura, above the accessory nerve, and below the glossopharyngeal and vagus nerves. The endoscope showed a small and soft aneurysm at the VBJ. (C) Combined retrosigmoid and FLA. Left side: The posterolateral craniotomy was enlarged until the sigmoid–transverse sinus junction was exposed. The lateral retraction of the cerebellar hemisphere provided the exposure of the cisternal segment of the V, and VII–VIII CNs, and the surgical view of the aneurysm was widened along the CPA. (D) Combined posterior transpetrosal retrolabyrinthine and FLA. Left side: The posterior transpetrosal approach enhanced the visualization of the cisternal portions of the facial and vestibulocochlear nerves, and increased the exposure of the homolateral surface of the aneurysm. (E) Combined posterior transpetrosal transcochlear and FLA. Left side: The vestibule–cochlea complex has been sacrificed and the VII CN has been fully exposed and mobilized posteromedially. The approach provided a trajectory almost parallel to the surface of the clivus, widening the surgical exposure of the anterolateral surface of the aneurysm, which was found to be attached to the clivus. The VI CN was stretched and dislocated laterally by the aneurysm, in both sides. (F-G) Combined anterior and posterior transpetrosal and FLA. Left side: Through the anterior transpetrosal approach, the superolateral portion of the aneurysm, upper clivus, and the related neurovascular structures were exposed. The combination of the anterior and posterior transpetrosal approaches with the extended FLA provided a supra/infratentorial exposure of the aneurysm; the homolateral superior, lateral, and inferior surfaces of the lesion were visualized. (H-I) Combined anterior and posterior transpetrosal approach and FLA. Right side: On the right side, the cisternal portion of the trigeminal nerve was compressed and dislocated laterally by the aneurysm. The basilar apex, PCA, SCA, and PComA were exposed bilaterally. On the right side, the upper part (almost 1 cm) of the BA was also exposed and a transitional configuration of the PcomA was found. I. The tentorial splitting increased the visualization of the upper surface of the aneurysm.
posterior circulation aneurysm (RR, 2.5; 95% CI, 1.6–4.1) and symptomatic aneurysm (RR, 4.4; 95% CI, 2.8–6.8). The case described in this article fulfills 5 of those 6 risk factors. Although some concerns have been raised regarding the potential influence of biased data (either due to publication bias or heterogeneity in methodological quality) analyzed in the above-mentioned meta-regression study,
the study has made an important contribution to neurosurgical knowledge by providing essential data for clinical decision-making in patients with unruptured intracranial aneurysms.17 Our case unfortunately demonstrates that the decisionmaking process might not be always straightforward, especially in case of GAs or difficult anatomical sites.
4 F. Graziano et al.
Downloaded by [University of Sherbrooke] at 02:25 03 November 2015
Lesson learned from the microsurgical approaches to the VBJ GA The fully extended FLA (with transcondylar and supracondylar extensions) allowed the exposure of both the VAs and of the homolateral PICA. The infratonsillar retraction of the cerebellar hemisphere exposed the cisternal segment of the lower cranial nerves (CNs) from the IX to the XII, running behind the VA. The inferior surface of the aneurysm was visualized, but neither the basilar artery (BA) nor the neck of the aneurysm could be observed (Fig. 2A). The lateral suboccipital craniotomy was then extended until exposure of the sigmoid-transverse sinus junction was obtained (combined retrosigmoid and FLA). The lateral retraction of the cerebellar hemisphere allowed the exposure of the cisternal segment of the V, and VII–VIII CNs, and the surgical view of the aneurysm was widened along the CPA. The view of the BA and petroclival region was obscured by the lateral portion of the aneurysm, where the GDCs were also identified (Fig. 2B). The extended posterior transpetrosal approach allowed a complete visualization of the cisternal and intracanalicular portions of the facial nerve, while the vestibulocochlear nerves were sacrificed. The approach provided a trajectory almost parallel to the surface of the clivus, widening the surgical exposure of the anterolateral surface of the aneurysm, which was found to be attached to the clivus. Again, the BA was not exposed, and the neck of the aneurysm was hidden behind the lesion, in front of the brainstem (Fig. 2D and E). The VI CN was stretched and dislocated laterally by the aneurysm, in both sides. Through an anterior transpetrosal approach, the superolateral portion of the aneurysm, upper clivus, and related neurovascular structures were exposed (Fig. 2F–I). The superior surface of the aneurysm was located 1 cm below the posterior clinoid processes. The anterolateral surface of the cerebral peduncle was severely compressed by the dome of the aneurysm. The oculomotor, trochlear, and trigeminal nerves were visualized from their origin at the brainstem en route to the cavernous sinus and skull base foramina. On the right side, the cisternal portion of the trigeminal nerve was compressed and dislocated laterally by the aneurysm (Fig. 2H and I). The basilar apex, posterior cerebral artery (PCA), superior cerebellar artery (SCA), and posterior communicating artery (PComA) were exposed bilaterally. In addition, the upper part (almost 1 cm) of the BA was exposed and a transitional configuration of the PcomA was observed. The combination of the anterior and posterior transpetrosal approaches with the extended FLA provided a supra/ infratentorial exposure of the aneurysm; the homolateral superior, lateral, and inferior surfaces of the lesion were visualized.
Neurosurgical audit In the present study, we performed the most suitable skull base approaches to expose the giant lesion, in order to evaluate if, in this case, having this specific anatomical aspect, the microsurgery would have been superior to the endovascular techniques in treating the aneurysm. The microsurgical dissection demonstrated that none of the surgical approach was able to completely expose the lesion precluding the proximal and distal vascular control. The GA was extremely embedded
in the brainstem and the BA was compressed, precluding any chances to reach the aneurysm’s neck and to dissect the copious perforating artery network arising from the aneurysm. Our neurosurgical audit has shown that in such a condition, the microsurgery is not a treatment option to be considered and, now, we can confirm that the endovascular technique was the best option for the patient.
Limits of the postmortem study The main limitation of the present audit is the lack of recent premortem computed tomography or CT, magnetic resonance imaging (MRI), or Digital subtraction angiography (DSA) images. This aspect is crucial as it might raise concerns regarding possible posttreatment evolution of the lesion, and therefore might lead us to conclude that the anatomical findings at dissection may not represent the original state of the vascular lesion at the time of initial endovascular treatment.
Conclusion While it is important to bear in mind that each therapeutic modality may provide either benefits or risks to the patient, the audit conducted in this case of VBJ GA showed that in such challenging lesions the endovascular modalities might be the strategy of choice. Noteworthily, securing a GA, and preventing its rupture, does not always provide a lifetime cure for the patient. Only considering GA as a veritable brain disease will help in assessing the right balance between advantages and disadvantages of each therapeutic strategy. Declaration of interest: The authors report no declaration of interest concerning the materials or methods used in this study or the findings specified in this paper. The authors alone are responsible for the content and writing of the paper.
References 1. Collice M, Arena O, D’Aliberti G, et al. Aneurysms of the vertebrobasilar junction area: preliminary experience in endovascular, surgical management. Acta Neurochir (Wien) 1997;139:124–33. 2. Drake CG. The treatment of aneurysms of the posterior circulation. Clin Neurosurg 1979;26:96–144. 3. Spetzler RF, Riina HA, Lemole GM Jr. Giant aneurysms. Neurosurgery 2001;49:902–8. 4. Tiyaworabun S, Wanis A, Schirmer M, Bock WJ. Aneurysms of the vertebro-basilar system: clinical analysis, follow-up results. Acta Neurochir (Wien) 1982;63:221–9. 5. Le Roux PD, Richard Winn H. Surgical decision making for the treatment of cerebral aneurysms. Youmans: Neurological Surgery, 5th ed. Pennsylvania: Saunders; 1996:1793–1812. 6. Spetzler RF, Hadley MN, Rigamonti D, et al. Aneurysms of the basilar artery treated with circulatory arrest, hypothermia, barbiturate cerebral protection. J Neurosurg 1988;68:868–79. 7. Fiorella D. Pipeline in clinical practice in 2011. Neuroradiology 2012;54:277–8. 8. Guglielmi G, Viñuela F, Duckwiler G, et al. Endovascular treatment of posterior circulation aneurysms by electrothrombosis using electrically detachable coils. J Neurosurg 1992;77:515–24. 9. Cantore G, Santoro A, Guidetti G, et al. Surgical treatment of giant intracranial aneurysms: current viewpoint. Neurosurgery 2008;63:279–89; discussion 289–90. 10. Drake CG. Giant intracranial aneurysms: experience with surgical treatment in 174 patients. Clin Neurosurg 1979;26:12–95.
Vertebrobasilar junction giant aneurysm 5
Downloaded by [University of Sherbrooke] at 02:25 03 November 2015
11. Gonzalez NR, Duckwiler G, Jahan R, Murayama Y, Viñuela F. Challenges in the endovascular treatment of giant intracranial aneurysms. Neurosurgery 2006;59:S113–24; discussion S3–13. 12. Hernesniemi J, Vapalahti M, Niskanen M, Kari A. Management outcome for vertebrobasilar artery aneurysms by early surgery. Neurosurgery 1992;31:857–61; discussion 861–2. 13. Lawton MT, Raudzens PA, Zabramski JM, Spetzler RF. Hypothermic circulatory arrest in neurovascular surgery: evolving indications, predictors of patient outcome. Neurosurgery 1998;43:10–20; discussion 20–1. 14. Peluso JP, van Rooij WJ, Sluzewski M, Beute GN. Aneurysms of the vertebrobasilar junction: incidence, clinical presentation,
outcome of endovascular treatment. AJNR Am J Neuroradiol 2007;28:1747–51. 15. Schievink WI, Wijdicks EF, Piepgras DG, et al. The poor prognosis of ruptured intracranial aneurysms of the posterior circulation. J Neurosurg 1995;82:791–5. 16. Wermer MJ, van der Schaaf IC, Algra A, Rinkel GJ. Risk of rupture of unruptured intracranial aneurysms in relation to patient and aneurysm characteristics: an updated meta-analysis. Stroke 2007;38:1404–10. 17. Van der Jagt M, Koudstaal PJ, Dippel DW, Habbema JD. Methodological quality and publication bias in observational studies on risk of rupture of unruptured intracranial aneurysms. Stroke 2008;39:e11.
ISSN: 0268-8697 (Print) 1360-046X (Online) Journal homepage: http://www.tandfonline.com/loi/ibjn20
Vertebrobasilar junction giant aneurysm: Lessons learned from a neurosurgical audit and anatomical investigation Francesca Graziano, Mario Ganau, Vittorio Maria Russo, Domenico G. Iacopino & Arthur John Ulm III To cite this article: Francesca Graziano, Mario Ganau, Vittorio Maria Russo, Domenico G. Iacopino & Arthur John Ulm III (2015): Vertebrobasilar junction giant aneurysm: Lessons learned from a neurosurgical audit and anatomical investigation, British Journal of Neurosurgery, DOI: 10.3109/02688697.2015.1023778 To link to this article: http://dx.doi.org/10.3109/02688697.2015.1023778
Published online: 20 Apr 2015.
Submit your article to this journal
Article views: 21
View related articles
View Crossmark data
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ibjn20 Download by: [University of Sherbrooke]
Date: 03 November 2015, At: 02:25
British Journal of Neurosurgery, 2015; Early Online: 1–5 © 2015 The Neurosurgical Foundation ISSN: 0268-8697 print / ISSN 1360-046X online DOI: 10.3109/02688697.2015.1023778
Education Report
Vertebrobasilar junction giant aneurysm: Lessons learned from a neurosurgical audit and anatomical investigation Francesca Graziano1,2, Mario Ganau1, Vittorio Maria Russo1, Domenico G. Iacopino2 & Arthur John Ulm III1 1Department of Neurosurgery, Louisiana State University, New Orleans, Louisiana, USA and 2Department of Experimental
Downloaded by [University of Sherbrooke] at 02:25 03 November 2015
Biomedicine and Clinical Neurosciences, Neurosurgical Clinic, AOPU “P. Giaccone” Universita’ degli Studi di Palermo, Italy
laboratory work uphold a great informative value regarding the complex management of those lesions. The related takehome messages are therefore worth sharing with the BJN community of young trainees.
Abstract The treatment of vascular lesions of the vertebrobasilar junction (VBJ) remains a challenging task in the neurosurgical practice and the gold standard therapy is still under debate. In this article, the authors report a detailed postmortem study of a VBJ giant aneurysm (GA) previously endovascularly treated. Although the decision-making process for the vast majority of neurosurgical treatment can nowadays be accurately carried out during the preoperative planning (i.e., with the aid of neuroimaging fusion protocols, neuronavigation platforms, etc.) meant to maximize the anatomical understanding of the lesions and minimize possible intraprocedural challenges, this postmortem study represents the ultimate essence of neurosurgical audit as the laboratory investigations allowed to reevaluate the clinical history of VBJ GA, and reassess the multiple strategies available for its treatment with a straightforward anatomical perspective. Specifically, the lessons learned through this clinical and laboratory work uphold a great educational value regarding the complex management of those lesions, including the possible role of combined skull base surgical approaches.
Case description A 61-year-old woman without significant comorbidities apart from blood pressure (hypertension) was diagnosed with a GA (3.8 cm 3.6 cm) located at the VBJ after neuroradiological investigations for chronic six-month occipital headache and postural instability. The aneurysm was treated by the last author (A.J.U.) through a two-staged embolization procedure. At first, a 4.5 mm 20 mm Neuroform Stent was placed across the neck of the aneurysm and 1 month later, the aneurysm was filled with 11 Guglielmi detachable coils (GDC-18) (Fig. 1). Five months later, the aneurysm recanalized (Fig. 1C). An endovascular treatment of the aneurysm was chosen again (also considering the personal preferences of the patient). As per protocol, clinical balloon test occlusion or BTO was performed. Nevertheless, the patient developed slurred speech and decreased level of consciousness just 5 min after the occlusion of both vertebral arteries (VAs). In the light of this result, the aneurysm was endosaccularly embolized with coils and Onyx (Fig. 1D). In addition, the right non-dominant vertebral artery was occluded below the postero-inferior cerebellar artery (PICA) origin, with Onyx 34. The patient was ultimately discharged to the rehabilitation unit at her neurological baseline. Fourteen months later, the patient died due to a cause unrelated to the aneurysm; upon her husband’s request, her body was donated to the Department of Neurosurgery, Louisiana State University, New Orleans for anatomical dissection and educational training. The description of the thorough neurosurgical audit and microsurgical investigation conducted on this case is given below.
Keywords: anatomical dissection; neurosurgical audit; skull base approaches; vertebrobasilar junction aneurysms
Introduction The treatment of vascular lesions of the vertebrobasilar junction (VBJ) remains a challenging task in the neurosurgical practice and the gold standard therapy is still under debate. In this article, the authors report a detailed postmortem study of a VBJ giant aneurysm (GA) that was previously treated endovascularly and discuss the potential role which would have had a microsurgical approach in exposing and managing the lesion. This study represents the ultimate essence of neurosurgical audit, as the lessons learned through this clinical and
Correspondence: Francesca Graziano, MD, Department of Experimental Biomedicine and Clinical Neurosciences, Neurosurgical Clinic, AOPU “P. Giaccone” Universita’ degli Studi di Palermo, 129, Via del Vespro, 90100 Palermo, Italy. Tel: 39 (393) 5684317. Fax: ( 39) 091 655 2393. E-mail: [email protected] Received for publication 9 June 2014; accepted 22 February 2015
1
2 F. Graziano et al. exposed in order to open the dura as close to the sinus as possible and increasing the surgical view along the cerebellopontine angle (CPA) (Fig. 2C).
Downloaded by [University of Sherbrooke] at 02:25 03 November 2015
Posterior transpetrosal approach with its extensions The posterior transpetrosal approach included various degrees of mastoid and labyrinth resection in order to minimize the neurovascular structures retraction and to provide a surgical view as close as possible to the giant lesion. The first degree of mastoid resection was the retrolabyrinthine extension. It included a complete mastoidectomy, exposing of the bony capsule of the semicircular canals and skeletonizing of the mastoid segment of the facial nerve. In the translabyrinthine extension, the semicircular canals and the vestibule were fully drilled out, and the tympanic, labyrinthine, and meatal segments of the facial nerve were skeletonized. Afterward, the transcochlear extension was performed, the otic capsule was drilled completely, the labyrinthine segment of the facial nerve was transposed posteriorly, and the cochlea and the petrous apex were drilled out (Fig. 2D and E). Fig. 1. A–D. DSA of the vertebrobasilar system. (A) Left Vertebral DSA. The GA at the VBJ presented an almost spherical shape and a large neck, measuring 14 mm. The GA shifted the BA to the right side. The right PICA rose almost at the level of the VBJ. (B) I Endovascular treatment. Left vertebral DSA. As part I of the two-staged procedure, a Neuroform Stent was placed across the aneurysm neck. One month later, the aneurysm was filled with GDC coils. (C–D) Aneurysm recanalization and II Endovascular treatment. After 5 months, the recanalization occurred. Four GDC 18 coils were used to create a scaffold and a total of 5 cc of Onyx 34 and 4 cc of Onyx 18 were injected in the recanalized region.
Laboratory investigation The specimen was embalmed and the arteries and veins were injected with colored silicone. The combination of the following skull base approaches was performed bilaterally: the far-lateral approach (FLA) with its transcondylar and supracondylar extensions; the retrosigmoid, the presigmoid with its retro, translabyrinthine, and transcochlear extensions; and the extended anterior transpetrosal.
Far-lateral approach with its extensions A lateral suboccipital craniotomy was performed, including resection of the posterolateral rim of the foramen magnum, and extending laterally until the medial edge of the sigmoid sinus was exposed. Inferiorly and laterally, the craniotomy was extended over the condylar fossa and condylar canal. The ipsilateral posterior arch of C1 from the sulcus arteriosus to the midline was removed. The transverse foramen of C1 was opened up and the V3 segment of the VA was mobilized and transposed medially. Afterward, the transcondylar extension was carried out. Subsequently, the jugular tubercle was reached and removed extradurally so that a wide exposure with a flat angle along the foramen magnum, lower clivus, and anterolateral brainstem was provided (Fig. 2A and B).
Retrosigmoid approach The posterolateral craniotomy was enlarged until the posterior aspect of the sigmoid transverse sinus junction was
Anterior transpetrosal approach A subtemporal craniotomy, extending down to the floor of the middle fossa, was added to the previous bone work. The dura was elevated from the floor in order to expose, progressively, the middle meningeal artery, the greater superficial petrosal nerve or GSPN, and the mandibular branch of the trigeminal nerve. The medial insertion of the tentorium was then exposed and the posterolateral triangle or Kawase triangle was identified and, in order to access the upper clivus, the shallow volume of petrous apex, in the Kawase triangle, was drilled out (Fig. 2F–I).
Discussion Vascular lesions located at the VBJ are rare and complex pathologies with a dismal natural history.1–4 Even though the high risk of rupture makes their treatment mandatory, the management is extremely challenging and associated with high rate of morbidity and mortality. Several treatment options are currently available, including either surgical or endovascular technique.1,5–15 Different factors may play a critical role in the selection of the most appropriate therapy, surgical or endovascular, including the preoperative clinical and neurological assessment of the patient, the features of the aneurysm and its relationship with surrounding neural, osseous, and vascular structures. The different risk factors for bleeding of unruptured intracranial aneurysms have been described in several studies; noteworthily, a relatively recent paper was focused on univariate and multivariate analyses conducted through a meta-regression study including all the clinical series published during the decade 1996–2006.16 From these analyses several statistically significant risk factors for rupture emerged, some were already known and some others were not officially stated before: age 60 years [risk ratio (RR), 2.0; 95% confidence interval (CI), 1.1–3.7], female gender (RR, 1.6; 95% CI, 1.1–2.4), Japanese or Finnish descent (RR, 3.4; 95% CI, 2.6–4.4), size 5 mm (RR, 2.3; 95% CI, 1.0–5.2),
Downloaded by [University of Sherbrooke] at 02:25 03 November 2015
Vertebrobasilar junction giant aneurysm 3
Fig. 2. Microsurgical exposure. (A) Full-extended (transcondylar and supracondylar) FLA. Left side: The infratonsillar retraction of the cerebellar hemisphere exposed the cisternal segment of the lower CNs from the IX to the XII, running behind the VA. The inferior surface of the aneurysm was visualized. (B) Endoscopic view trough the FLA. Left side: The endoscope was introduced through the surgical corridor gained by the extradural resection of the jugular tubercle, just beside the retracted dura, above the accessory nerve, and below the glossopharyngeal and vagus nerves. The endoscope showed a small and soft aneurysm at the VBJ. (C) Combined retrosigmoid and FLA. Left side: The posterolateral craniotomy was enlarged until the sigmoid–transverse sinus junction was exposed. The lateral retraction of the cerebellar hemisphere provided the exposure of the cisternal segment of the V, and VII–VIII CNs, and the surgical view of the aneurysm was widened along the CPA. (D) Combined posterior transpetrosal retrolabyrinthine and FLA. Left side: The posterior transpetrosal approach enhanced the visualization of the cisternal portions of the facial and vestibulocochlear nerves, and increased the exposure of the homolateral surface of the aneurysm. (E) Combined posterior transpetrosal transcochlear and FLA. Left side: The vestibule–cochlea complex has been sacrificed and the VII CN has been fully exposed and mobilized posteromedially. The approach provided a trajectory almost parallel to the surface of the clivus, widening the surgical exposure of the anterolateral surface of the aneurysm, which was found to be attached to the clivus. The VI CN was stretched and dislocated laterally by the aneurysm, in both sides. (F-G) Combined anterior and posterior transpetrosal and FLA. Left side: Through the anterior transpetrosal approach, the superolateral portion of the aneurysm, upper clivus, and the related neurovascular structures were exposed. The combination of the anterior and posterior transpetrosal approaches with the extended FLA provided a supra/infratentorial exposure of the aneurysm; the homolateral superior, lateral, and inferior surfaces of the lesion were visualized. (H-I) Combined anterior and posterior transpetrosal approach and FLA. Right side: On the right side, the cisternal portion of the trigeminal nerve was compressed and dislocated laterally by the aneurysm. The basilar apex, PCA, SCA, and PComA were exposed bilaterally. On the right side, the upper part (almost 1 cm) of the BA was also exposed and a transitional configuration of the PcomA was found. I. The tentorial splitting increased the visualization of the upper surface of the aneurysm.
posterior circulation aneurysm (RR, 2.5; 95% CI, 1.6–4.1) and symptomatic aneurysm (RR, 4.4; 95% CI, 2.8–6.8). The case described in this article fulfills 5 of those 6 risk factors. Although some concerns have been raised regarding the potential influence of biased data (either due to publication bias or heterogeneity in methodological quality) analyzed in the above-mentioned meta-regression study,
the study has made an important contribution to neurosurgical knowledge by providing essential data for clinical decision-making in patients with unruptured intracranial aneurysms.17 Our case unfortunately demonstrates that the decisionmaking process might not be always straightforward, especially in case of GAs or difficult anatomical sites.
4 F. Graziano et al.
Downloaded by [University of Sherbrooke] at 02:25 03 November 2015
Lesson learned from the microsurgical approaches to the VBJ GA The fully extended FLA (with transcondylar and supracondylar extensions) allowed the exposure of both the VAs and of the homolateral PICA. The infratonsillar retraction of the cerebellar hemisphere exposed the cisternal segment of the lower cranial nerves (CNs) from the IX to the XII, running behind the VA. The inferior surface of the aneurysm was visualized, but neither the basilar artery (BA) nor the neck of the aneurysm could be observed (Fig. 2A). The lateral suboccipital craniotomy was then extended until exposure of the sigmoid-transverse sinus junction was obtained (combined retrosigmoid and FLA). The lateral retraction of the cerebellar hemisphere allowed the exposure of the cisternal segment of the V, and VII–VIII CNs, and the surgical view of the aneurysm was widened along the CPA. The view of the BA and petroclival region was obscured by the lateral portion of the aneurysm, where the GDCs were also identified (Fig. 2B). The extended posterior transpetrosal approach allowed a complete visualization of the cisternal and intracanalicular portions of the facial nerve, while the vestibulocochlear nerves were sacrificed. The approach provided a trajectory almost parallel to the surface of the clivus, widening the surgical exposure of the anterolateral surface of the aneurysm, which was found to be attached to the clivus. Again, the BA was not exposed, and the neck of the aneurysm was hidden behind the lesion, in front of the brainstem (Fig. 2D and E). The VI CN was stretched and dislocated laterally by the aneurysm, in both sides. Through an anterior transpetrosal approach, the superolateral portion of the aneurysm, upper clivus, and related neurovascular structures were exposed (Fig. 2F–I). The superior surface of the aneurysm was located 1 cm below the posterior clinoid processes. The anterolateral surface of the cerebral peduncle was severely compressed by the dome of the aneurysm. The oculomotor, trochlear, and trigeminal nerves were visualized from their origin at the brainstem en route to the cavernous sinus and skull base foramina. On the right side, the cisternal portion of the trigeminal nerve was compressed and dislocated laterally by the aneurysm (Fig. 2H and I). The basilar apex, posterior cerebral artery (PCA), superior cerebellar artery (SCA), and posterior communicating artery (PComA) were exposed bilaterally. In addition, the upper part (almost 1 cm) of the BA was exposed and a transitional configuration of the PcomA was observed. The combination of the anterior and posterior transpetrosal approaches with the extended FLA provided a supra/ infratentorial exposure of the aneurysm; the homolateral superior, lateral, and inferior surfaces of the lesion were visualized.
Neurosurgical audit In the present study, we performed the most suitable skull base approaches to expose the giant lesion, in order to evaluate if, in this case, having this specific anatomical aspect, the microsurgery would have been superior to the endovascular techniques in treating the aneurysm. The microsurgical dissection demonstrated that none of the surgical approach was able to completely expose the lesion precluding the proximal and distal vascular control. The GA was extremely embedded
in the brainstem and the BA was compressed, precluding any chances to reach the aneurysm’s neck and to dissect the copious perforating artery network arising from the aneurysm. Our neurosurgical audit has shown that in such a condition, the microsurgery is not a treatment option to be considered and, now, we can confirm that the endovascular technique was the best option for the patient.
Limits of the postmortem study The main limitation of the present audit is the lack of recent premortem computed tomography or CT, magnetic resonance imaging (MRI), or Digital subtraction angiography (DSA) images. This aspect is crucial as it might raise concerns regarding possible posttreatment evolution of the lesion, and therefore might lead us to conclude that the anatomical findings at dissection may not represent the original state of the vascular lesion at the time of initial endovascular treatment.
Conclusion While it is important to bear in mind that each therapeutic modality may provide either benefits or risks to the patient, the audit conducted in this case of VBJ GA showed that in such challenging lesions the endovascular modalities might be the strategy of choice. Noteworthily, securing a GA, and preventing its rupture, does not always provide a lifetime cure for the patient. Only considering GA as a veritable brain disease will help in assessing the right balance between advantages and disadvantages of each therapeutic strategy. Declaration of interest: The authors report no declaration of interest concerning the materials or methods used in this study or the findings specified in this paper. The authors alone are responsible for the content and writing of the paper.
References 1. Collice M, Arena O, D’Aliberti G, et al. Aneurysms of the vertebrobasilar junction area: preliminary experience in endovascular, surgical management. Acta Neurochir (Wien) 1997;139:124–33. 2. Drake CG. The treatment of aneurysms of the posterior circulation. Clin Neurosurg 1979;26:96–144. 3. Spetzler RF, Riina HA, Lemole GM Jr. Giant aneurysms. Neurosurgery 2001;49:902–8. 4. Tiyaworabun S, Wanis A, Schirmer M, Bock WJ. Aneurysms of the vertebro-basilar system: clinical analysis, follow-up results. Acta Neurochir (Wien) 1982;63:221–9. 5. Le Roux PD, Richard Winn H. Surgical decision making for the treatment of cerebral aneurysms. Youmans: Neurological Surgery, 5th ed. Pennsylvania: Saunders; 1996:1793–1812. 6. Spetzler RF, Hadley MN, Rigamonti D, et al. Aneurysms of the basilar artery treated with circulatory arrest, hypothermia, barbiturate cerebral protection. J Neurosurg 1988;68:868–79. 7. Fiorella D. Pipeline in clinical practice in 2011. Neuroradiology 2012;54:277–8. 8. Guglielmi G, Viñuela F, Duckwiler G, et al. Endovascular treatment of posterior circulation aneurysms by electrothrombosis using electrically detachable coils. J Neurosurg 1992;77:515–24. 9. Cantore G, Santoro A, Guidetti G, et al. Surgical treatment of giant intracranial aneurysms: current viewpoint. Neurosurgery 2008;63:279–89; discussion 289–90. 10. Drake CG. Giant intracranial aneurysms: experience with surgical treatment in 174 patients. Clin Neurosurg 1979;26:12–95.
Vertebrobasilar junction giant aneurysm 5
Downloaded by [University of Sherbrooke] at 02:25 03 November 2015
11. Gonzalez NR, Duckwiler G, Jahan R, Murayama Y, Viñuela F. Challenges in the endovascular treatment of giant intracranial aneurysms. Neurosurgery 2006;59:S113–24; discussion S3–13. 12. Hernesniemi J, Vapalahti M, Niskanen M, Kari A. Management outcome for vertebrobasilar artery aneurysms by early surgery. Neurosurgery 1992;31:857–61; discussion 861–2. 13. Lawton MT, Raudzens PA, Zabramski JM, Spetzler RF. Hypothermic circulatory arrest in neurovascular surgery: evolving indications, predictors of patient outcome. Neurosurgery 1998;43:10–20; discussion 20–1. 14. Peluso JP, van Rooij WJ, Sluzewski M, Beute GN. Aneurysms of the vertebrobasilar junction: incidence, clinical presentation,
outcome of endovascular treatment. AJNR Am J Neuroradiol 2007;28:1747–51. 15. Schievink WI, Wijdicks EF, Piepgras DG, et al. The poor prognosis of ruptured intracranial aneurysms of the posterior circulation. J Neurosurg 1995;82:791–5. 16. Wermer MJ, van der Schaaf IC, Algra A, Rinkel GJ. Risk of rupture of unruptured intracranial aneurysms in relation to patient and aneurysm characteristics: an updated meta-analysis. Stroke 2007;38:1404–10. 17. Van der Jagt M, Koudstaal PJ, Dippel DW, Habbema JD. Methodological quality and publication bias in observational studies on risk of rupture of unruptured intracranial aneurysms. Stroke 2008;39:e11.
