Accepted Manuscript New techniques for improving the safety of transcranial endoscopic skull-base surgery Wei Zhu, M.D. Ph.D. Ying Mao, M.D. Ph.D. PII:
S1878-8750(14)00214-9
DOI:
10.1016/j.wneu.2014.03.001
Reference:
WNEU 2289
To appear in:
World Neurosurgery
Received Date: 20 November 2013 Accepted Date: 4 March 2014
Please cite this article as: Zhu W, Mao Y, New techniques for improving the safety of transcranial endoscopic skull-base surgery, World Neurosurgery (2014), doi: 10.1016/j.wneu.2014.03.001. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT New techniques for improving the safety of transcranial endoscopic skull-base surgery
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The concept of endoneurosurgery has exited for over one century since Victor de l’Espinasse, as the first surgeon, performed a neuroendoscopic procedure, in which he resected choroid plexus in infants with hydrocephalus using a cystoscope in 1910 (2). However, until recent few decades, modern neuroendoscopy is becoming a more and more flourishing field with the requirement of minimally invasive neurosurgery, and the innovation and implementation of emerging technology, such as refinements in telescope and lens design, light sources, instrumentation and neuronavigation.
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Endoscopic skull-base surgery via transcranial approaches However, endoneurosurgery is still mainly performed in intraventricular surgery, endonasal skull-base surgery, and spine surgery. Only very few cases were reported in which neuroendoscopy was applied to treat skull-base lesions via transcranial approaches, such as pterional or retrosigmoidal approach. Endoscopy as the solo optic device to access the posterior fossa was first reported in China (7). Jarrahy and Shahinian et al (3, 4, 6) reported a series of case of endoscopic vascular decompressions (EVD) for the treatment of trigeminal neuralgia and glossopharyngeal neuralgia, and resection of vestibular schwannomas. Their studies highlighted many advantages of purely endoscopic approaches, including the superior visualization of the anatomy and panoramic views, facilitating the decompression through the available operating window with otherwise narrow views. After retrospectively comparing their EVD cohort of 255 patients with trigeminal neuralgia with a larger series of microvascular decompression of over 1,600 patients, they found that EVD resulted in a higher pain relief rate in contrast to microvascular decompression right after operation and at the 3-year follow-up. Other reports (1) described the technics of extraendoscopic neurosurgery for resection of CPA lesions including epidermoid cyst, residual ependymoma, and pilocytic astrocytoma of the cerebellar hemisphere. The difficulties of transcranial endoscopic skull-base surgery Trancranial endoscopic skull-base surgery is usually performed as endoscopic-controlled or endoscopic-assisted procedure. Compared to endonasal skull-base endoneurosurgery, this procedure lacks natural and safe surgical corridor to access to the surgical field. Frequently inserting and maneuvering an endoscope through a small craniotomy bears a risk of injuring the brain or neurovascular structures. Despite the advances in optic device and endoscopic instrumentation have been achieved, this limitation still makes the endoscopic manipulation difficult. Therefore, trancranial endoneurosurgery is often performed to treat cystic and small lesions, or those with poor blood supply. To track the endoscopy tip to prevent damage to the brain along the surgical corridor, or to identify the anatomic structures of endoscopic images, image guidance systems (IGS) are often used. However, the
ACCEPTED MANUSCRIPT
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operator needs to convert these two-dimensional images into three-dimensional ones in his mind. The brain shift during operation due to CSF evacuation and brain retraction is another problem, which prevents the navigation from being able to reflect intraoperative actual anatomy. Thus, training in cadaver is still not replaceable for novice surgeons before they can perform a real neuroendoscopic operation. In recent few decades, instruments and devices for pure endoscopic techniques were developed, which makes the endoscopic maneuver safer and more efficient. These refined instruments are much more frequently applied in endonasal endoscopic skull-base surgery, during which they could be safely inserted and extracted through the nasal cavity. However, endoscopic maneuver via trancranial approaches is still not easy. To prevent the damage to the surrounding neurovascular structures during the procedure, establishing an artificial working channel through the surgical corridor would be helpful.
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Training of endoneurosurgery As any other new surgical techniques, there is a learning curve in endoneurosurgery. It is challenging for both novice neurosurgeons and experienced ones who used to microneurosurgery. Endoscopic surgery is performed in three-dimensional space but viewed on a two-dimensional monitor. Depth perception of the complex neurovascular structures is also a big challenge for beginner. The operators should adapt to these unfamiliar instruments, and the operative time will be much longer during the initial endoscopic cases. Endoscopic cadaver course is crucial for novice endoscopic neurosurgeons to become more familiar with the surgical anatomy and instruments. Virtual endoscopy (5) is also an efficient training platform for novice neurosurgeons. It provided not only the simulated endoscopic view, but also the endoscopic handling. It also helps in converting the two-dimensional radiological images to three-dimensional depiction of anatomy during actual endoscopic surgery. Virtual endoscopy has been widely applied in third ventriculostomy, endonasal surgery as pre-operative planning and training tool.
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In the paper by Feigl et al, the authors described a voxel based neuronavigation system with 3D perspective image rendering for endoscopic procedures through keyhole approaches to the skull base. By applying this novel system, the operators would be able to track the endoscopy tip more easily, which helped to prevent injury to the surrounding anatomic structure through the keyhole surgery. The system also provided the neurosurgeon not only with the live image of the endoscope but on the same screen it simultaneously showed a virtual 3D voxel based endoscopic image from the same view as the endoscope camera. The virtual images are reconstructed from pre-operative MRI or CCT images, also provided a transparent visualization of neurovascular structures (such as internal carotid artery) hidden behind the bony structures during the procedure. This novel system combined the techniques of IGS and virtual endoscopy, which could potentially make the transcranial endoneurosurgical procedures safer. Its main contribution could be achieved as a
ACCEPTED MANUSCRIPT training tool for novice endoscopic neurosurgeons. Besides the limitations of this system and study that the authors mentioned, brain shift due to CSF evacuation or brain retraction should be considered during actual IGS endoneurosurgery. The operators also need to keep in mind that actual surgical experience and skill could not be replaced by only practice on training platforms.
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Referances Di X, Sui A, Hakim R, Wang M, Warnke JP: Endoscopic minimally invasive neurosurgery: emerging techniques and expanding role through an extensive review of the literature and our own experience - part II: extraendoscopic neurosurgery. Pediatr Neurosurg 47: 327-336, 2011 Grant JA: Victor Darwin Lespinasse: a biographical sketch. Neurosurgery 39:1232-1233, 1996 Jarrahy R, Cha ST, Eby JB, Berci G, Shahinian HK: Fully endoscopic vascular decompression of the glossopharyngeal nerve. J Craniofac Surg 13: 90-95, 2002 Jarrahy R, Eby JB, Cha ST, Shahinian HK: Fully endoscopic vascular decompression of the trigeminal nerve. Minimally Invasive Neurosurgery 45: 32-35, 2002 Neubauer A, Wolfsberger S: Virtual endoscopy in neurosurgery: a review. Neurosurgery 72(Suppl): 97-106, 2013 Shahinian HK, Eby JB, Ocon M: Fully endoscopic excision of vestibular schwannomas. Minim Invasive Neurosurg. 47: 329-332, 2004 Wang H, Zhang D, Wang B: [Endoscopic surgery of the cerebellopontine angle]. Zhonghua Er Bi Yan Hou Ke Za Zhi 31:153-155, 1996. Chinese
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ACCEPTED MANUSCRIPT
S1878-8750(14)00214-9
DOI:
10.1016/j.wneu.2014.03.001
Reference:
WNEU 2289
To appear in:
World Neurosurgery
Received Date: 20 November 2013 Accepted Date: 4 March 2014
Please cite this article as: Zhu W, Mao Y, New techniques for improving the safety of transcranial endoscopic skull-base surgery, World Neurosurgery (2014), doi: 10.1016/j.wneu.2014.03.001. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT New techniques for improving the safety of transcranial endoscopic skull-base surgery
RI PT
The concept of endoneurosurgery has exited for over one century since Victor de l’Espinasse, as the first surgeon, performed a neuroendoscopic procedure, in which he resected choroid plexus in infants with hydrocephalus using a cystoscope in 1910 (2). However, until recent few decades, modern neuroendoscopy is becoming a more and more flourishing field with the requirement of minimally invasive neurosurgery, and the innovation and implementation of emerging technology, such as refinements in telescope and lens design, light sources, instrumentation and neuronavigation.
AC C
EP
TE D
M AN U
SC
Endoscopic skull-base surgery via transcranial approaches However, endoneurosurgery is still mainly performed in intraventricular surgery, endonasal skull-base surgery, and spine surgery. Only very few cases were reported in which neuroendoscopy was applied to treat skull-base lesions via transcranial approaches, such as pterional or retrosigmoidal approach. Endoscopy as the solo optic device to access the posterior fossa was first reported in China (7). Jarrahy and Shahinian et al (3, 4, 6) reported a series of case of endoscopic vascular decompressions (EVD) for the treatment of trigeminal neuralgia and glossopharyngeal neuralgia, and resection of vestibular schwannomas. Their studies highlighted many advantages of purely endoscopic approaches, including the superior visualization of the anatomy and panoramic views, facilitating the decompression through the available operating window with otherwise narrow views. After retrospectively comparing their EVD cohort of 255 patients with trigeminal neuralgia with a larger series of microvascular decompression of over 1,600 patients, they found that EVD resulted in a higher pain relief rate in contrast to microvascular decompression right after operation and at the 3-year follow-up. Other reports (1) described the technics of extraendoscopic neurosurgery for resection of CPA lesions including epidermoid cyst, residual ependymoma, and pilocytic astrocytoma of the cerebellar hemisphere. The difficulties of transcranial endoscopic skull-base surgery Trancranial endoscopic skull-base surgery is usually performed as endoscopic-controlled or endoscopic-assisted procedure. Compared to endonasal skull-base endoneurosurgery, this procedure lacks natural and safe surgical corridor to access to the surgical field. Frequently inserting and maneuvering an endoscope through a small craniotomy bears a risk of injuring the brain or neurovascular structures. Despite the advances in optic device and endoscopic instrumentation have been achieved, this limitation still makes the endoscopic manipulation difficult. Therefore, trancranial endoneurosurgery is often performed to treat cystic and small lesions, or those with poor blood supply. To track the endoscopy tip to prevent damage to the brain along the surgical corridor, or to identify the anatomic structures of endoscopic images, image guidance systems (IGS) are often used. However, the
ACCEPTED MANUSCRIPT
SC
RI PT
operator needs to convert these two-dimensional images into three-dimensional ones in his mind. The brain shift during operation due to CSF evacuation and brain retraction is another problem, which prevents the navigation from being able to reflect intraoperative actual anatomy. Thus, training in cadaver is still not replaceable for novice surgeons before they can perform a real neuroendoscopic operation. In recent few decades, instruments and devices for pure endoscopic techniques were developed, which makes the endoscopic maneuver safer and more efficient. These refined instruments are much more frequently applied in endonasal endoscopic skull-base surgery, during which they could be safely inserted and extracted through the nasal cavity. However, endoscopic maneuver via trancranial approaches is still not easy. To prevent the damage to the surrounding neurovascular structures during the procedure, establishing an artificial working channel through the surgical corridor would be helpful.
EP
TE D
M AN U
Training of endoneurosurgery As any other new surgical techniques, there is a learning curve in endoneurosurgery. It is challenging for both novice neurosurgeons and experienced ones who used to microneurosurgery. Endoscopic surgery is performed in three-dimensional space but viewed on a two-dimensional monitor. Depth perception of the complex neurovascular structures is also a big challenge for beginner. The operators should adapt to these unfamiliar instruments, and the operative time will be much longer during the initial endoscopic cases. Endoscopic cadaver course is crucial for novice endoscopic neurosurgeons to become more familiar with the surgical anatomy and instruments. Virtual endoscopy (5) is also an efficient training platform for novice neurosurgeons. It provided not only the simulated endoscopic view, but also the endoscopic handling. It also helps in converting the two-dimensional radiological images to three-dimensional depiction of anatomy during actual endoscopic surgery. Virtual endoscopy has been widely applied in third ventriculostomy, endonasal surgery as pre-operative planning and training tool.
AC C
In the paper by Feigl et al, the authors described a voxel based neuronavigation system with 3D perspective image rendering for endoscopic procedures through keyhole approaches to the skull base. By applying this novel system, the operators would be able to track the endoscopy tip more easily, which helped to prevent injury to the surrounding anatomic structure through the keyhole surgery. The system also provided the neurosurgeon not only with the live image of the endoscope but on the same screen it simultaneously showed a virtual 3D voxel based endoscopic image from the same view as the endoscope camera. The virtual images are reconstructed from pre-operative MRI or CCT images, also provided a transparent visualization of neurovascular structures (such as internal carotid artery) hidden behind the bony structures during the procedure. This novel system combined the techniques of IGS and virtual endoscopy, which could potentially make the transcranial endoneurosurgical procedures safer. Its main contribution could be achieved as a
ACCEPTED MANUSCRIPT training tool for novice endoscopic neurosurgeons. Besides the limitations of this system and study that the authors mentioned, brain shift due to CSF evacuation or brain retraction should be considered during actual IGS endoneurosurgery. The operators also need to keep in mind that actual surgical experience and skill could not be replaced by only practice on training platforms.
5. 6. 7.
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Referances Di X, Sui A, Hakim R, Wang M, Warnke JP: Endoscopic minimally invasive neurosurgery: emerging techniques and expanding role through an extensive review of the literature and our own experience - part II: extraendoscopic neurosurgery. Pediatr Neurosurg 47: 327-336, 2011 Grant JA: Victor Darwin Lespinasse: a biographical sketch. Neurosurgery 39:1232-1233, 1996 Jarrahy R, Cha ST, Eby JB, Berci G, Shahinian HK: Fully endoscopic vascular decompression of the glossopharyngeal nerve. J Craniofac Surg 13: 90-95, 2002 Jarrahy R, Eby JB, Cha ST, Shahinian HK: Fully endoscopic vascular decompression of the trigeminal nerve. Minimally Invasive Neurosurgery 45: 32-35, 2002 Neubauer A, Wolfsberger S: Virtual endoscopy in neurosurgery: a review. Neurosurgery 72(Suppl): 97-106, 2013 Shahinian HK, Eby JB, Ocon M: Fully endoscopic excision of vestibular schwannomas. Minim Invasive Neurosurg. 47: 329-332, 2004 Wang H, Zhang D, Wang B: [Endoscopic surgery of the cerebellopontine angle]. Zhonghua Er Bi Yan Hou Ke Za Zhi 31:153-155, 1996. Chinese
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