- Email: [email protected]
Importance of Continued Support for Microsurgical Anatomical Studies
Perspectives Commentary on: Petrosectomy and Topographical Anatomy in Traditional Kawase and Posterior Intradural Petrous Apecectomy (PIPA) Approach: An Anatomical Study by Rigante et al. World Neurosurg 86:93-102, 2016
Importance of Continued Support for Microsurgical Anatomical Studies Kaith K. Almefty and Robert F. Spetzler
A
lthough the petroclival region was once considered a surgical “no-man’s land,” the past 30 years have witnessed remarkable success in the surgical treatment of neoplastic and vascular lesions in this region. Located deep within the cranium and densely populated with critical neurovascular structures, the petroclival region has few, if any, comparative anatomical spaces that are as surgically challenging. The surgical successes in this region have been built on 2 major contributions: 1) the introduction of the surgical microscope to the fields of otology and neurosurgery, and 2) a surge of study in the microsurgical anatomy of the space. Now provided with the necessary tool and map, surgeons performing operations in this region have advanced from an era of exploration to an era of refinement.
The current study by Rigante et al. is an anatomical study of the petroclival region that compares the exposure and extent of petrosectomy provided by the posterior intradural petrous apicectomy (PIPA) and the middle fossa anterior petrosectomy, both of which were supplemented with the 0-degree and 30-degree endoscope. The PIPA consists of a retrosigmoid intradural suprameatal approach (RISA) with a posterior intradural petrous apicectomy. The study found 389 mm3 of additional petrosectomy volume with the middle fossa approach than with the PIPA approach (mean volume, 1978 mm3 vs. 1589 mm3). The authors also further detail the intradural and extradural neurovascular structures exposed by each approach and with the supplementation of the endoscope. On the basis of the anatomical findings of their study, Rigante et al. conclude that the PIPA approach is best suited for primarily posterior cranial fossa lesions with minor extension into the middle cranial fossa. The middle fossa approach is better suited for primarily middle
Key words Kawase approach - petroclival - PIPA - RISA - skull base -
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www.SCIENCEDIRECT.com
Abbreviations and Acronyms PIPA: Posterior intradural petrous apicectomy RISA: Retrosigmoid intradural suprameatal approach
fossa lesions with minor extension into the posterior fossa and, in particular, for those lesions requiring good visualization of the anterior brainstem, the fifth nerve, and the petrous and cavernous segments of the carotid artery. As previously mentioned, the anatomy of the petroclival region has been studied extensively. The extraordinary work of skull base laboratories around the world has defined in great detail the surgical anatomy not only of this region but also of the entire skull base in quantitative, illustrative, and photographic terms. The body of work and the anatomical atlases that have been produced are remarkable, instructive, and, to the surgeon, beautiful. In regard to the present topic, the surgical anatomy of the middle fossa and the RISA approaches have been described in great detail by the Rhoton group,1,2 and our own group has performed a quantitative anatomical comparison of the 2 approaches.3 Given this knowledge, we should raise not only the present question of whether the study by Rigante et al. contributes to our knowledge base but also the broader question of whether anatomical studies and laboratories are still worthy of investment in the current highly competitive funding environment. Rigante et al.’s study provided information on 2 areas not yet addressed by the prior quantitative analysis of the petroclival region: 1) a direct comparison of the quantity of petrous apex that can be drilled through each approach, and 2) the additional anatomical exposure provided by the endoscope. These findings highlight 2—among other—reasons for which continued support of our anatomical laboratories is essential. First, the selection of a surgical approach for a given lesion is highly nuanced, and while consideration should be given to the clinical status of the patient, the characteristics of the lesion, and the goals of surgery,
Department of Neurosurgery, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona, USA To whom correspondence should be addressed: Robert F. Spetzler, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2016) 86:46-47. http://dx.doi.org/10.1016/j.wneu.2015.09.086
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2015.09.086
PERSPECTIVES
the foundation for the decision must be on a firm anatomical understanding of the exposure provided by each approach. The operating room is neither the place to discover that a particular approach does not allow one to meet the surgical goal nor the place to perform an unnecessarily extensive dissection. Second, while changes in human anatomy may take many millennia, the effect of technological advancements and improvements in surgical technique rapidly alter surgical anatomy. The application of the endoscope to skull base surgery has done more than allow the development of new approaches that require new surgical anatomical studies; it has also expanded the exposure provided by traditional approaches as highlighted in the present study. Achieving the full potential of new technologies and, in particular, of optical technologies in neurosurgery will require further anatomical study. Anatomical study may seem rudimentary compared with the high-tech modern basic science fields; however, it is unlikely that any field has as rapid and as important a translational value in neurosurgery. Works such as this one by Rigante et al. may immediately be integrated into clinical practice, leading to improvements in patient care. The highly practical nature of the work often enhances the potential for the discovery of new surgical approaches and techniques. Finally, the anatomy laboratory plays an essential role in neurosurgical education and training. The fine anatomical dissections and atlases that have been produced are an inadequate substitute for individual trainee dissection time. This point has been
REFERENCES 1. Tanriover N, Sanus GZ, Ulu MO, Tanriverdi T, Akar Z, Rubino PA, et al. Middle fossa approach: microsurgical anatomy and surgical technique from the neurosurgical perspective. Surg Neurol. 2009;71:586-596. discussion; 596.
2. Seoane E, Rhoton AL Jr. Suprameatal extension of the retrosigmoid approach: microsurgical anatomy. Neurosurgery. 1999;44:553-560.
3. Chang SW, Wu A, Gore P, Beres E, Porter RW, Preul MC, et al. Quantitative comparison of Kawase’s approach versus the retrosigmoid approach: implications for tumors involving both middle and posterior fossae. Neurosurgery. 2009; 64:ons44-ons51. discussion; ons51-ons42.
well demonstrated in many of our medical schools, where due to cost restraints, traditional gross anatomy courses have been restructured as so-called dry laboratories offering only prosections or plastinated specimens. Most of these schools have since reverted to full dissection courses after studies demonstrated a detrimental effect on medical education.4-10 Additionally, changes in the resident training environment, with workhour restrictions and increased oversight, have increased the need for educational opportunities and skill acquisition outside the operating room. Significant emphasis has been placed on surgical simulators to meet this need. However, developing a simulator with the complexities of human tissue and neuroanatomy is challenging, and cadaveric dissection remains the most valuable method of surgical simulation. As expressed by Rhoton, “There is no finish line for this effort. . Surgical anatomy will continue to be the most fundamental science to neurosurgery in the future.”11 Researchers such as Rigante et al. should be congratulated for answering a new anatomical question, our journals should continue to encourage and publish anatomical studies, and our neurosurgery departments should continue to create and fund anatomical laboratories for research and educational purposes.
ACKNOWLEDGMENT We wish to thank the Neuroscience Publications staff at Barrow Neurological Institute for editorial assistance.
4. Goldman E. Building a low-cost gross anatomy laboratory: a big step for a small university. Anat Sci Educ. 2010;3:195-201.
9. Moxham BJ, Plaisant O. Perception of medical students towards the clinical relevance of anatomy. Clin Anat. 2007;20:560-564.
5. Dyer GS, Thorndike ME. Quidne mortui vivos docent? The evolving purpose of human dissection in medical education. Acad Med. 2000;75:969-979.
10. Korf HW, Wicht H, Snipes RL, Timmermans JP, Paulsen F, Rune G, et al. The dissection course— necessary and indispensable for teaching anatomy to medical students. Ann Anat. 2008;190:16-22.
6. Gunderman RB, Wilson PK. Viewpoint: exploring the human interior: the roles of cadaver dissection and radiologic imaging in teaching anatomy. Acad Med. 2005;80:745-749. 7. Rizzolo LJ, Stewart WB. Should we continue teaching anatomy by dissection when.? Anat Rec B New Anat. 2006;289:215-218. 8. Azer SA, Eizenberg N. Do we need dissection in an integrated problem-based learning medical course? Perceptions of first- and second-year students. Surg Radiol Anat. 2007;29:173-180.
WORLD NEUROSURGERY 86: 46-47, FEBRUARY 2016
11. Rhoton AL Jr. Fifty years of neurosurgery. World Neurosurg. 2011;75:163-173. Citation: World Neurosurg. (2016) 86:46-47. http://dx.doi.org/10.1016/j.wneu.2015.09.086 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2016 Elsevier Inc. All rights reserved.
www.WORLDNEUROSURGERY.org
47
Importance of Continued Support for Microsurgical Anatomical Studies Kaith K. Almefty and Robert F. Spetzler
A
lthough the petroclival region was once considered a surgical “no-man’s land,” the past 30 years have witnessed remarkable success in the surgical treatment of neoplastic and vascular lesions in this region. Located deep within the cranium and densely populated with critical neurovascular structures, the petroclival region has few, if any, comparative anatomical spaces that are as surgically challenging. The surgical successes in this region have been built on 2 major contributions: 1) the introduction of the surgical microscope to the fields of otology and neurosurgery, and 2) a surge of study in the microsurgical anatomy of the space. Now provided with the necessary tool and map, surgeons performing operations in this region have advanced from an era of exploration to an era of refinement.
The current study by Rigante et al. is an anatomical study of the petroclival region that compares the exposure and extent of petrosectomy provided by the posterior intradural petrous apicectomy (PIPA) and the middle fossa anterior petrosectomy, both of which were supplemented with the 0-degree and 30-degree endoscope. The PIPA consists of a retrosigmoid intradural suprameatal approach (RISA) with a posterior intradural petrous apicectomy. The study found 389 mm3 of additional petrosectomy volume with the middle fossa approach than with the PIPA approach (mean volume, 1978 mm3 vs. 1589 mm3). The authors also further detail the intradural and extradural neurovascular structures exposed by each approach and with the supplementation of the endoscope. On the basis of the anatomical findings of their study, Rigante et al. conclude that the PIPA approach is best suited for primarily posterior cranial fossa lesions with minor extension into the middle cranial fossa. The middle fossa approach is better suited for primarily middle
Key words Kawase approach - petroclival - PIPA - RISA - skull base -
46
www.SCIENCEDIRECT.com
Abbreviations and Acronyms PIPA: Posterior intradural petrous apicectomy RISA: Retrosigmoid intradural suprameatal approach
fossa lesions with minor extension into the posterior fossa and, in particular, for those lesions requiring good visualization of the anterior brainstem, the fifth nerve, and the petrous and cavernous segments of the carotid artery. As previously mentioned, the anatomy of the petroclival region has been studied extensively. The extraordinary work of skull base laboratories around the world has defined in great detail the surgical anatomy not only of this region but also of the entire skull base in quantitative, illustrative, and photographic terms. The body of work and the anatomical atlases that have been produced are remarkable, instructive, and, to the surgeon, beautiful. In regard to the present topic, the surgical anatomy of the middle fossa and the RISA approaches have been described in great detail by the Rhoton group,1,2 and our own group has performed a quantitative anatomical comparison of the 2 approaches.3 Given this knowledge, we should raise not only the present question of whether the study by Rigante et al. contributes to our knowledge base but also the broader question of whether anatomical studies and laboratories are still worthy of investment in the current highly competitive funding environment. Rigante et al.’s study provided information on 2 areas not yet addressed by the prior quantitative analysis of the petroclival region: 1) a direct comparison of the quantity of petrous apex that can be drilled through each approach, and 2) the additional anatomical exposure provided by the endoscope. These findings highlight 2—among other—reasons for which continued support of our anatomical laboratories is essential. First, the selection of a surgical approach for a given lesion is highly nuanced, and while consideration should be given to the clinical status of the patient, the characteristics of the lesion, and the goals of surgery,
Department of Neurosurgery, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona, USA To whom correspondence should be addressed: Robert F. Spetzler, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2016) 86:46-47. http://dx.doi.org/10.1016/j.wneu.2015.09.086
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2015.09.086
PERSPECTIVES
the foundation for the decision must be on a firm anatomical understanding of the exposure provided by each approach. The operating room is neither the place to discover that a particular approach does not allow one to meet the surgical goal nor the place to perform an unnecessarily extensive dissection. Second, while changes in human anatomy may take many millennia, the effect of technological advancements and improvements in surgical technique rapidly alter surgical anatomy. The application of the endoscope to skull base surgery has done more than allow the development of new approaches that require new surgical anatomical studies; it has also expanded the exposure provided by traditional approaches as highlighted in the present study. Achieving the full potential of new technologies and, in particular, of optical technologies in neurosurgery will require further anatomical study. Anatomical study may seem rudimentary compared with the high-tech modern basic science fields; however, it is unlikely that any field has as rapid and as important a translational value in neurosurgery. Works such as this one by Rigante et al. may immediately be integrated into clinical practice, leading to improvements in patient care. The highly practical nature of the work often enhances the potential for the discovery of new surgical approaches and techniques. Finally, the anatomy laboratory plays an essential role in neurosurgical education and training. The fine anatomical dissections and atlases that have been produced are an inadequate substitute for individual trainee dissection time. This point has been
REFERENCES 1. Tanriover N, Sanus GZ, Ulu MO, Tanriverdi T, Akar Z, Rubino PA, et al. Middle fossa approach: microsurgical anatomy and surgical technique from the neurosurgical perspective. Surg Neurol. 2009;71:586-596. discussion; 596.
2. Seoane E, Rhoton AL Jr. Suprameatal extension of the retrosigmoid approach: microsurgical anatomy. Neurosurgery. 1999;44:553-560.
3. Chang SW, Wu A, Gore P, Beres E, Porter RW, Preul MC, et al. Quantitative comparison of Kawase’s approach versus the retrosigmoid approach: implications for tumors involving both middle and posterior fossae. Neurosurgery. 2009; 64:ons44-ons51. discussion; ons51-ons42.
well demonstrated in many of our medical schools, where due to cost restraints, traditional gross anatomy courses have been restructured as so-called dry laboratories offering only prosections or plastinated specimens. Most of these schools have since reverted to full dissection courses after studies demonstrated a detrimental effect on medical education.4-10 Additionally, changes in the resident training environment, with workhour restrictions and increased oversight, have increased the need for educational opportunities and skill acquisition outside the operating room. Significant emphasis has been placed on surgical simulators to meet this need. However, developing a simulator with the complexities of human tissue and neuroanatomy is challenging, and cadaveric dissection remains the most valuable method of surgical simulation. As expressed by Rhoton, “There is no finish line for this effort. . Surgical anatomy will continue to be the most fundamental science to neurosurgery in the future.”11 Researchers such as Rigante et al. should be congratulated for answering a new anatomical question, our journals should continue to encourage and publish anatomical studies, and our neurosurgery departments should continue to create and fund anatomical laboratories for research and educational purposes.
ACKNOWLEDGMENT We wish to thank the Neuroscience Publications staff at Barrow Neurological Institute for editorial assistance.
4. Goldman E. Building a low-cost gross anatomy laboratory: a big step for a small university. Anat Sci Educ. 2010;3:195-201.
9. Moxham BJ, Plaisant O. Perception of medical students towards the clinical relevance of anatomy. Clin Anat. 2007;20:560-564.
5. Dyer GS, Thorndike ME. Quidne mortui vivos docent? The evolving purpose of human dissection in medical education. Acad Med. 2000;75:969-979.
10. Korf HW, Wicht H, Snipes RL, Timmermans JP, Paulsen F, Rune G, et al. The dissection course— necessary and indispensable for teaching anatomy to medical students. Ann Anat. 2008;190:16-22.
6. Gunderman RB, Wilson PK. Viewpoint: exploring the human interior: the roles of cadaver dissection and radiologic imaging in teaching anatomy. Acad Med. 2005;80:745-749. 7. Rizzolo LJ, Stewart WB. Should we continue teaching anatomy by dissection when.? Anat Rec B New Anat. 2006;289:215-218. 8. Azer SA, Eizenberg N. Do we need dissection in an integrated problem-based learning medical course? Perceptions of first- and second-year students. Surg Radiol Anat. 2007;29:173-180.
WORLD NEUROSURGERY 86: 46-47, FEBRUARY 2016
11. Rhoton AL Jr. Fifty years of neurosurgery. World Neurosurg. 2011;75:163-173. Citation: World Neurosurg. (2016) 86:46-47. http://dx.doi.org/10.1016/j.wneu.2015.09.086 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2016 Elsevier Inc. All rights reserved.
www.WORLDNEUROSURGERY.org
47