Initial Experience Using a High-Definition 3-Dimensional Exoscope System for Microneurosurgery

Initial Experience Using a High-Definition 3-Dimensional Exoscope System for Microneurosurgery Abstract BACKGROUND The operative microscope and endoscope have significantly advanced modern neurosurgery. These devices are nonetheless limited by high costs and suboptimal optics, ergonomics, and maneuverability. A recently developed extracorporeal telescope (“exoscope”) operative system combines characteristics from both the operative microscope and endoscope and provides an affordable, portable, high-definition operative experience. Widespread use of exoscopes in neurosurgery has previously been limited by a lack of stereopsis with 2-dimensional(2-D) monitors. OBJECTIVE To assess the surgical potential of a novel, 3-D, high-definition (4K-HD) exoscope system. METHODS Assess dissection time and visualization of critical structures in a series of human cadaveric cranial neurosurgical approaches with the 3-D 4K-HD exoscope as compared to a standard operating microscope. RESULTS Dissection times and visualization of critical structures was comparable with the 3-D 4K-HD exoscope and a standard operating microscope. The low-profile exoscope nonetheless allowed for larger operative corridors, enhanced instrument maneuverability, and less obstruction in passing instrumentation. The large monitor also resulted in an immersive surgical experience, and gave multiple team members the same high-quality view as the primary operator. Finally, the exoscope possessed a more ergonomically favorable setup as compared to the traditional microscope, allowing the surgeon to be in a neutral position despite the operative angle. CONCLUSION The novel 3-D 4K-HD exoscope system possesses favorable optics, ergonomics, and maneuverability as compared to the traditional operating microscope, with the exoscope's shared surgical view possessing obvious educational and workflow advantages. Further clinical trials are justified to validate this initial cadaveric experience. Exoscope, Operating microscope, Microneurosurgery, Stereopsis ABBREVIATIONS ABBREVIATIONS 2-D 2-dimensional LBL line-by-line OM operating microscope OR operating room The introduction and utilization of the operative microscope had a profound impact on operative technique and neurosurgical care. More recently, neurosurgeons have adopted the use of telescope-based surgery (ie, endoscopy) and broadened its application. Endoscopy in other surgical disciplines offered improvements in surgeon comfort, decreased fatigue, and decreased operative morbidity.1-7 Due to confined operative corridors in cranial surgery, smaller diameter scopes are required for most neurosurgical procedures. Neuroendoscopes therefore have shorter focal distances and require closer positioning to the focal point. These technical constraints translate into increased difficulty maneuvering instruments around the scope and frequent obstruction of the lens by blood and tissue. These surgical workflow issues ultimately limit neurosurgical application of endoscopy. In response to the limitations of both the endoscope and operative microscope, a high-definition extracorporeal telescope (“Exoscope”) system was developed over the past decade.7,8 Previously described exoscope systems (HDXO-SCOPE, VITOM) consisted of a telescope with a mean focal distance of 20 to 30 cm, fiberoptic light source, camera head, pneumatic scope holder, and a high-definition video display. Compared to the endoscope, the exoscope has a wider field of view (600 vs 25 mm) and greater mean focal distance (200-300 vs 3-20 mm), permitting the passage of standard neurosurgical instruments with relative ease. In addition, unlike the operative microscope, the exoscope is light and compact (650 g vs 100 kg), and much less expensive. Furthermore, the exoscope system not only allows both the surgeon and assistant to operate while viewing conveniently positioned high-definition video monitors, but it also allows the rest of operating room (OR) team to follow the procedure with ease. One of the major limitations and criticisms of the prior exoscope system was the lack of stereopsis, as compared with the operating microscope(OM). In response, a 3-dimensional (3-D) 4K-HD exoscope system has been developed to optimize surgical visualization, while maintaining the ergonomic advantage and maneuverability that the exoscope affords. Given the emerging nature of this technology, previous evaluations of exoscopes in neurosurgery are limited to the initial laboratory and clinical experiences with the 2-D exoscopes.7-9 We build upon this work by describing our experience with the novel 3-D 4K-HD exoscope system on a series of human cadaveric specimens. METHODS General Features of the Exoscope System The 3-D video exoscope (Sony Olympus Medical Solutions, Inc, Tokyo, Japan) consists of right and left complementary metal-oxide semiconductor cameras. Both cameras have a resolution of 3840 × 2160 pixels. The system output is in line-by-line (LBL) mode 3-D and can be displayed on 3-D compatible monitors. The cameras are mounted on a proprietary counterbalance arm operated by a traditional dead man switch. The dead man switch, focus, and zoom controls are all located on the camera body. Additional settings are controlled at the console to which the exoscope and counter balance arm are mounted. The system runs on a proprietary Unix-like operating system with a graphical user interface controlled by a touch screen at the console. The light source is a fiber optic LED source. The monitor used in conjunction with this exoscope is a 3840 × 2160 resolution prototype monitor which utilizes the 3-D LBL output of the system to display full-resolution circularly polarized passive 3-D images. Circular polarization 3-D lenses are required to proper viewing of the images. The exoscope has seamless optical and digital zooming that is controlled by either a hand or foot switch. Total magnification ranges from 1.1 to 25.8× with a zooming ratio of 1 to 12 × (6 × optical and 2 × digital). The focal length of the exoscope is 220 to 550 mm, with focusing controlled by hand at the exoscope headpiece or by use of foot pedal. Field of view ranges from 7.5 to 171 mm. Cadaveric Microdissections Seven neurosurgeons with varying experience (ranging from junior resident to senior clinical professor) performed a series of 5 cranial exposures and brain dissections on injected human cadaveric specimens. Each exposure was performed simultaneously on separate specimens utilizing both the 3-D 4K-HD exoscope system and a standard operative microscope (Leica, M320 F12, Leica Microsystems, Wetzler, Germany). The 5 surgical approaches and goals of each exposure are described below. Frontotemporal Orbitozygomatic A curvilinear incision was made from approximately 3 cm inferior to the zygoma to just short of the contralateral midpupillary line. The scalp and superficial temporalis fascia were reflected anteriorly. The temporalis muscle was incised along the superior temporal line and mobilized posteroinferiorly. The periorbital was then bluntly dissected from the bone, starting at the lateral orbital rim and continuing along the superior orbital rim medially to the supraorbital notch. McCarty (fronto-orbital) and temporal burr holes were drilled, and the bony cuts for a 1-piece frontotemporal orbitozygomatic craniotomy10 were performed. Additional removal of the sphenoid ridge and the temporal bone were performed until flush with the posterior orbital wall and floor of the middle fossa, respectively. Next, the dura was opened in a curvilinear fashion and hinged anteriorly. The sylvian fissure was identified and opened from lateral to medial with sharp dissection without retraction. The optic nerve was then identified and the arachnoid of the opticocarotid cistern was opened sharply. Microdissection continued without the utilization of a retractor system, with the aim to identify the following major structures: ipsilateral and contralateral optic nerves, optic chiasm, lamina terminalis, internal carotid artery, anterior cerebral artery, anterior communicating artery, middle cerebral artery, posterior communicating artery, basilar artery, and oculomotor nerve. Retromastoid A curved retromastoid skin incision was made positioned 3 cm medial to the ear and extending from the top of the ear to the mastoid tip. A craniectomy was then performed extending from the transverse sinus superiorly to the foramen magnum inferiorly. The dura was incised parallel to the transverse and sigmoid sinus. A self-retaining retractor was positioned on the lateral cerebellum and flocculus for increased visualization. The arachnoid overlying the cranial nerves and posterior fossa vessels was opened. Microdissection continued with the aim to identify the following major structures: CN IV-XII, internal auditory canal, jugular foramen, hypoglossal canal, vertebral artery, posterior inferior cerebellar artery, anterior inferior cerebellar artery, superior cerebellar artery. Suboccipital A linear skin incision was made extending from the C2 spinous process to 2 cm above the inion. A midline craniectomy was then performed extending from the foramen magnum to just below the transverse sinus. A Y-shaped dural opening was subsequently created, with retraction of the dural flaps superiorly and laterally. Self-retaining retractors were then utilized to separate both cerebellar tonsils, and the overlying arachnoid incised. Microdissection continued with the aim to identify the following major structures: cerebellar tonsils, vermis, bilateral posterior inferior cerebellar arteries, foramen of luschka, obex, floor of the fourth ventricle, and cerebral aqueduct. Supraorbital (Eyebrow) A linear incision was made along the superior border of the eyebrow from the supraorbital notch medially, to 1 cm lateral to the bony edge of the eyebrow. The incision extended through the fascia of the frontalis muscle, exposing the periosteum. The musclulocutaneous layer was retracted anteriorly with hooks. A single McCarty burr hole was placed exposing the periorbita and frontal dura. The first cut of the craniotomy was placed in a curved fashion from the burr hole, turned backwards and superiorly, and brought down just lateral to the supraorbital notch. An osteotome was then used to extend the craniotomy cuts across the orbital bar, and the fronto-orbital bone flap was removed after fracturing across the thin bone of the orbital roof. Next, the dura was opened in a curvilinear fashion and hinged anteriorly. The optic nerve was then identified and the arachnoid of the opticocarotid cistern was opened sharply. Microdissection continued without the utilization of a retractor system, with the aim to identify the following major structures: ipsilateral and contralateral optic nerves, optic chiasm, lamina terminalis, internal carotid artery, anterior cerebral artery, anterior communicating artery, middle cerebral artery, posterior communicating artery, basilar artery, and oculomotor nerve. Interhemispheric Transcallosal A right-sided U-shaped incision was made with the center-positioned anterior to the coronal suture, the hinge positioned laterally, and the apex crossing midline. A pair of burr holes were placed anteriorly and posteriorly straddling the superior sagittal sinus. A bone flap (∼4 × 6 cm) positioned two-thirds anterior and one-third posterior to the coronal suture was cut with the craniotome. The dura was opened in a U-shaped fashion and hinged toward the sagittal sinus. Self-retaining retractors were placed along the frontal lobe laterally, and the falx and sagittal sinus medially, to expand our corridor. We continued to deepen the exposure until the callosomarginal and pericollosal arteries were identified. Next, the body of the corpus callosum was identified and a 3-cm callosotomy was performed. Once the lateral ventricle was entered, the following structures were identified: septal vein, caudate vein, thalamostriate vein, foramen of monro, choroid plexus, fornix, and thalamus. RESULTS All predetermined structures were visualized using both microscope systems. The 3-D 4K-HD exoscope enabled high-resolution viewing of critical neuroanatomic landmarks across multiple cranial approaches (Figures 1-4). The dissections demonstrated in Figures 1 to 4 were completed by senior faculty and chief residents. In comparing the 2 systems, there was no difference in time to dissect and visualize the predetermined anatomic structures. More specifically, utilizing both the standard microscope and the exoscope all dissections were completed in a 25-min period. Craniotomies were not performed with use of either microscope system, as the microscopes were not utilized until opening of the dura. Two surgeons were able to operate simultaneously on the cadaveric specimen utilizing the exoscope. Instead of viewing through a binocular microscope, both operators viewed the 3-D monitor utilizing the 3-D glasses (see Figure 5). The primary and assisting surgeon had the same operating orientation and vantage point. As shown in the figure, the low-profile design of the exoscope easily allowed for both surgeons to view the monitor without obstruction. Additionally, the low-profile design allowed for larger operating corridors, enhanced instrument maneuverability, and less obstruction when passing of instruments compared to the traditional microscope. Video quality of the exoscope was rated excellent by all surgeons, and judged superior when compared with the traditional microscope. This was based on a simple video quality rating scale, which was assessed by 8 reviewers, specifically 5 faculty and 3 residents. Video quality was rated as inadequate, adequate, above average, or excellent. Additionally, because of the size of the 3-D monitor, the operating experience was as immersive as traditional binocular microscopes with oculars directly in front of the surgeon's eyes. FIGURE 1. View largeDownload slide Supraorbital approach via eyebrow incision, right side. Multiple images (A-D) from the 3-D 4K-HD exoscope demonstrating high-resolution views of critical neuroanatomic structures of the supraorbital approach. ON, optic nerve; OC, optic chiasm; CA, internal carotid artery; PCommA, posterior communicating artery; SHA, superior hypophyseal artery; HA, recurrent artery of Heubner; A1, A1 segment of anterior cerebral artery; AChA, anterior choroidal artery; BA, basilar artery; BT, basilar tip; P1, P1 segment of posterior cerebral artery. FIGURE 1. View largeDownload slide Supraorbital approach via eyebrow incision, right side. Multiple images (A-D) from the 3-D 4K-HD exoscope demonstrating high-resolution views of critical neuroanatomic structures of the supraorbital approach. ON, optic nerve; OC, optic chiasm; CA, internal carotid artery; PCommA, posterior communicating artery; SHA, superior hypophyseal artery; HA, recurrent artery of Heubner; A1, A1 segment of anterior cerebral artery; AChA, anterior choroidal artery; BA, basilar artery; BT, basilar tip; P1, P1 segment of posterior cerebral artery. FIGURE 2. View largeDownload slide Retrosigmoid approach, left side. Multiple images (A and B) from the 3-D 4K-HD exoscope demonstrating high-resolution views of critical neuroanatomic structures of the retrosigmoid approach. T, tentorium; SCA, superior cerebellar artery, P, pons; PICA, posterior inferior cerebellar artery. FIGURE 2. View largeDownload slide Retrosigmoid approach, left side. Multiple images (A and B) from the 3-D 4K-HD exoscope demonstrating high-resolution views of critical neuroanatomic structures of the retrosigmoid approach. T, tentorium; SCA, superior cerebellar artery, P, pons; PICA, posterior inferior cerebellar artery. FIGURE 3. View largeDownload slide Orbitozygomatic approach, right side. Multiple images (A and B) from the 3-D 4K-HD exoscope demonstrating high-resolution views of critical neuroanatomic structures of the orbitozygomatic approach. ON, optic nerve; OC, optic chiasm; ICA, internal carotid artery; PCommA, posterior communicating artery; A1 segment of anterior cerebral artery; A2 segment of anterior cerebral artery; HA, recurrent artery of Heubner; M3, M3 segment of middle cerebral artery. FIGURE 3. View largeDownload slide Orbitozygomatic approach, right side. Multiple images (A and B) from the 3-D 4K-HD exoscope demonstrating high-resolution views of critical neuroanatomic structures of the orbitozygomatic approach. ON, optic nerve; OC, optic chiasm; ICA, internal carotid artery; PCommA, posterior communicating artery; A1 segment of anterior cerebral artery; A2 segment of anterior cerebral artery; HA, recurrent artery of Heubner; M3, M3 segment of middle cerebral artery. FIGURE 4. View largeDownload slide Interhemispheric transcallosal approach, right side. Multiple images (A and B) from the 3-D 4K-HD exoscope demonstrating high-resolution views of critical neuroanatomic structures of the interhemispheric approach. F, falx; CC, corpus callosum; PcA, Pericallosal artery. FIGURE 4. View largeDownload slide Interhemispheric transcallosal approach, right side. Multiple images (A and B) from the 3-D 4K-HD exoscope demonstrating high-resolution views of critical neuroanatomic structures of the interhemispheric approach. F, falx; CC, corpus callosum; PcA, Pericallosal artery. FIGURE 5. View largeDownload slide Operative ergonomics of the 3-D 4K-HD exoscope. Image of the operative setup of the 3-D 4K-HD exoscope, demonstrating how 2 surgeons are able to operate simultaneously with a common orientation and vantage point, without obstruction. The low-profile design also allows for large operative corridors and easy maneuverability. FIGURE 5. View largeDownload slide Operative ergonomics of the 3-D 4K-HD exoscope. Image of the operative setup of the 3-D 4K-HD exoscope, demonstrating how 2 surgeons are able to operate simultaneously with a common orientation and vantage point, without obstruction. The low-profile design also allows for large operative corridors and easy maneuverability. The learning curve for the novel exoscope was minimal. All operators became facile with the device after a few minutes of use and a brief instruction tutorial. Junior residents utilizing the exoscope rated the device as simple to use with intuitive controls. When compared to standard operative microscopes, junior residents stated that the simplicity of the exoscope reduced the learning curve. All users completed a rating scale assessment of the exoscope utilizing a simple scale of less complex, equivalent, or more complex as compared to standard operative microscopes. All residents rated the device as less complex. Three of the faculty rated the exoscope as less complex compared to standard operative microscopes and 2 rated it as equivalent. Factors that simplify operative use are fewer operational buttons, point and view operability, smaller overall size, and no eyepiece adjustment. The trigger release, zoom, and focus buttons could all be controlled single handedly (see Figure 6). This simplicity resulted in enhanced operative efficiency when compared to the traditional microscope. Because the exoscope is a single module instead of 1 with 2 handles for control, surgeons found repositioning of the scope easier than traditional microscopes. Factors attributed to ease of repositioning included single hand repositioning, no balancing required, point and view dynamics without necessitating eyepiece repositioning, and compact overall size of exoscope (see Figures 5 and 6). FIGURE 6. View largeDownload slide Focus and zoom adjustment of the exoscope. Adjustment of the zoom and operative focus are controlled from the headpiece of the exoscope utilizing single-handed controls shown. Zoom and focus can also be adjusted with a foot pedal (not shown), allowing for continued bimanual operating during operative view adjustment. FIGURE 6. View largeDownload slide Focus and zoom adjustment of the exoscope. Adjustment of the zoom and operative focus are controlled from the headpiece of the exoscope utilizing single-handed controls shown. Zoom and focus can also be adjusted with a foot pedal (not shown), allowing for continued bimanual operating during operative view adjustment. Ergonomically, the exoscope allowed surgeons to operate in a neutral position, viewing the operative monitor positioned anterior to the surgical field. The monitor could be moved depending on surgical procedure and patient positioning. This benefit of the exoscope became most obvious during the suboccipital and retrosigmoid surgeries. During these approaches, the exoscope was aimed rostrally and upward, similar to traditional microscopes utilized during these procedures. However, because the monitor remained anterior to the surgeon, the surgeon maintained a neutral position while operating. In comparison, when utilizing the traditional microscope, the surgeon positioned themselves low with an upward viewing angle to accommodate the position of the microscope oculars. These ergonomic benefits of the exoscope were especially advantageous during longer surgical dissections. From an educational standpoint, the exoscope provided observers, residents, and students with the same surgical view as the primary surgeon on the 3-D high-definition monitor. Although difficult to quantitatively assess, junior residents stated that as observers their learning was enhanced because of the universal primary surgeon view. Additionally, the low profile of the exoscope allowed observers to better view the primary surgeon's instrument handling, hand/arm positioning, and overall orientation to the operative field as compared to traditional microscopes. All these factors provided an enhanced learning environment and when compared to the traditional microscope, this was an obvious educational benefit. DISCUSSION The 3-D 4K-HD exoscope trialed herein has a number of advantages for neurosurgical applications over traditional OM and endoscopic systems. As detailed in the reviews of prior, 2-D iterations of exoscopes,7,8 it is critical to differentiate this platform from endoscopy before comparing its performance to the OM, which it more closely resembles. Neuroendoscopes utilize long, narrow-diameter rod lenses with short focal lengths and ‘direct in-line’ visual trajectories, resulting in a relatively fixed, narrow field of view that is easily obscured with the introduction of surgical instruments or with moderate to brisk bleeding.7 Endoscopes also traditionally provide only a 2-D image of the surgical field. Given these limitations, neuroendoscopes have been mainly utilized only for niche operations in neurosurgery, such as transsphenoidal, endonasal skull base, or intraventricular procedures.7 Recently developed image-guided endoscopic systems have the potential to improve surgical precision and outcomes with this approach,11,12 but are subject to the same fundamental limitations as traditional endoscopy. In contrast, the 3-D 4K-HD exoscope has a longer focal length that allows it to be positioned outside of the surgical site. This results in a wider visual field that is not as easily obscured by blood or surgical instruments, and closely resembles the view surgeons are accustomed to with the OM. Unlike the OM, however, which provides only the primary surgeon with the highest quality stereoscopic image, the 3-D 4K-HD exoscope provides the same high-quality, 3-D immersive image to the entire OR. This visual arrangement is ideally suited for teaching hospitals as it facilitates resident and fellow education, and may also streamline OR work flow by allowing technicians and OR support staff to be more engaged in the procedure and better anticipate surgeon needs. The 3-D 4K-HD exoscope has a number of other advantages over the OM. First, the exoscope is lightweight and compact, making it easy to move into and out of the OR, and drape before bringing it into the sterile field. This is in stark contrast to the bulky traditional OM, which needs to be wheeled into and out of the OR with each procedure, and takes up significant floor space when in the OR. The 3-D 4K-HD exoscope is also easily positioned and repositioned throughout a case (addressing a criticism of prior exoscope iterations),7 and like previous versions has favorable ergonomics that allow the surgeon to sit in a natural position with their head upright.9 The exoscope also has a large depth of field, which reduces the need for refocusing during periods of dissection. These characteristics are critical to surgeon comfort in long cases, and limit the potential for fatigue and distractions from suboptimal positioning and/or out of focus surgical fields that are often encountered with the traditional OM. Finally, the cost of the exoscope system, including the 3-D monitor, glasses, and service and maintenance will be competitive with respect to the OM, a critical advantage in the increasingly cost-conscious healthcare environment. These combined features make the exoscope appealing for integration into the most cutting-edge neurosurgical programs, with the favorable economics and the portability of the system also facilitating access to this technology in developing countries with more limited resources.7 As with all new technology, there are certain disadvantages. The exoscope arm can obstruct the view of the operators or observers; however, this can be avoided with simple surgeon or exoscope position changes. Additionally, the exoscope relies on an external monitor, which is an added piece of equipment that must be accounted for in the operating suite and during nonuse. This requires knowledge of set up and space within the OR for viewing. No adverse effects such as vertigo or dizziness from wearing the 3-D glasses were reported. Limitations This study is the first neurosurgical experience with the 3-D 4K-HD exoscope, and while it convincingly demonstrated a comparable visual experience to the OM during cadaver dissections, its performance in living-patient surgery remains to be evaluated. The authors nonetheless feel that the advantages of the 3D 4K-HD exoscope noted in this trial, including ease of scope positioning, surgeon ergonomics, and a communal, immersive, high-resolution viewing experience, will only be amplified in a live OR setting. As future evaluations occur and surgeon exposure to this system increases, the authors predict that integration of this system into neurosurgery, and other fields utilizing surgical microscopy, will rapidly occur. CONCLUSION The 3-D 4K-HD is a novel exoscope system aimed at improving visualization and overall operative experience of the surgeon and entire surgical team. Visualization, ergonomics, and maneuverability all favored the exoscope system over the traditional microscope in this small series of cadaveric dissections, thereby supporting a proof of concept for this operative system. Our trial supports a planned clinical use assessment during human neurosurgery to validate this initial cadaveric experience. Disclosure Laboratory time for this work was supported by an unrestricted gift from Sony Olympus Medical Solutions, Inc (Tokyo, Japan). REFERENCES 1. Quilici PJ, Greaney EM, Quilici J, Anderson S. Laparoscopic inguinal hernia repair results: 131 cases. Am Surg . 1993; 59( 12): 824- 830. Google Scholar PubMed  2. Cruvinel MG, Duarte JB, Castro CH, Costa JR, Kux P. Multimodal approach to rapid discharge after endoscopic thoracic sympathectomy. Acta Anaesthesiol Scand . 2005; 49( 2): 238- 242. Google Scholar CrossRef Search ADS PubMed  3. McKenna RJ, Mahtabifard A, Pickens A, Kusuanco D, Fuller CB. Fast-tracking after video-assisted thoracoscopic surgery lobectomy, segmentectomy, and pneumonectomy. Ann Thorac Surg . 2007; 84( 5): 1663- 1667; discussion 1667-1668. Google Scholar CrossRef Search ADS PubMed  4. Bilimoria KY, Bentrem DJ, Merkow RP et al.   Laparoscopic-assisted vs. open colectomy for cancer: comparison of short-term outcomes from 121 hospitals. J Gastrointest Surg . 2008; 12( 11): 2001- 2009. Google Scholar CrossRef Search ADS PubMed  5. Shah SS, DiCristina CM, Bell LM, Ten Have T, Metlay JP. Primary early thoracoscopy and reduction in length of hospital stay and additional procedures among children with complicated pneumonia: results of a multicenter retrospective cohort study. Arch Pediatr Adolesc Med . 2008; 162( 7): 675- 681. Google Scholar CrossRef Search ADS PubMed  6. Tiberio GA, Baiocchi GL, Arru L et al.   Prospective randomized comparison of laparoscopic versus open adrenalectomy for sporadic pheochromocytoma. Surg Endosc . 2008; 22( 6): 1435- 1439. Google Scholar CrossRef Search ADS PubMed  7. Mamelak AN, Nobuto T, Berci G. Initial clinical experience with a high-definition exoscope system for microneurosurgery. Neurosurgery . 2010; 67( 2): 476- 483. Google Scholar CrossRef Search ADS PubMed  8. Mamelak AN, Danielpour M, Black KL, Hagike M, Berci G. A high-definition exoscope system for neurosurgery and other microsurgical disciplines: preliminary report. Surg Innov . 2008; 15( 1): 38- 46. Google Scholar CrossRef Search ADS PubMed  9. Mamelak AN, Drazin D, Shirzadi A, Black KL, Berci G. Infratentorial supracerebellar resection of a pineal tumor using a high definition video exoscope (VITOM®). J Clin Neurosci . 2012; 19( 2): 306- 309. Google Scholar CrossRef Search ADS PubMed  10. Andaluz N, van Loveren HR, Keller JT, Zuccarello M. The one-piece orbitopterional approach. Skull Base . 2003; 13( 4): 241- 245. Google Scholar CrossRef Search ADS PubMed  11. Spiotta AM, Fiorella D, Vargas J et al.   Initial multicenter technical experience with the Apollo device for minimally invasive intracerebral hematoma evacuation. Neurosurgery . 2015; 11( suppl 2): 243- 251; discussion 251. Google Scholar CrossRef Search ADS PubMed  12. Fiorella D, Gutman F, Woo H, Arthur A, Aranguren R, Davis R. Minimally invasive evacuation of parenchymal and ventricular hemorrhage using the Apollo system with simultaneous neuronavigation, neuroendoscopy and active monitoring with cone beam CT. J Neurointerv Surg . 2015; 7( 10): 752- 757. Google Scholar CrossRef Search ADS PubMed  COMMENT The authors summarize their initial experience with a new 3-D 4K-HD exoscope. The technology they describe appears to offer a new set of advantages over the traditional operating microscope, including maneuverability and ergonomics. This preliminary experience in cadaveric dissections provides optimism that functionally it performs at least as well as the traditional microscope. Certainly, further evaluation must be done in living patients and with a larger group of surgeons to fully identify the advantages and disadvantages of this new tool. New tools like this one help identify areas where our current technology lacks. Future, more widespread, attempts with this device will help to show whether it offers enough to become a more integral tool in the neurosurgeon's armamentarium. Rohan Chitale Nashville, Tennessee Copyright © 2017 by the Congress of Neurological Surgeons http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Operative Neurosurgery Oxford University Press

Initial Experience Using a High-Definition 3-Dimensional Exoscope System for Microneurosurgery

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Abstract

Abstract BACKGROUND The operative microscope and endoscope have significantly advanced modern neurosurgery. These devices are nonetheless limited by high costs and suboptimal optics, ergonomics, and maneuverability. A recently developed extracorporeal telescope (“exoscope”) operative system combines characteristics from both the operative microscope and endoscope and provides an affordable, portable, high-definition operative experience. Widespread use of exoscopes in neurosurgery has previously been limited by a lack of stereopsis with 2-dimensional(2-D) monitors. OBJECTIVE To assess the surgical potential of a novel, 3-D, high-definition (4K-HD) exoscope system. METHODS Assess dissection time and visualization of critical structures in a series of human cadaveric cranial neurosurgical approaches with the 3-D 4K-HD exoscope as compared to a standard operating microscope. RESULTS Dissection times and visualization of critical structures was comparable with the 3-D 4K-HD exoscope and a standard operating microscope. The low-profile exoscope nonetheless allowed for larger operative corridors, enhanced instrument maneuverability, and less obstruction in passing instrumentation. The large monitor also resulted in an immersive surgical experience, and gave multiple team members the same high-quality view as the primary operator. Finally, the exoscope possessed a more ergonomically favorable setup as compared to the traditional microscope, allowing the surgeon to be in a neutral position despite the operative angle. CONCLUSION The novel 3-D 4K-HD exoscope system possesses favorable optics, ergonomics, and maneuverability as compared to the traditional operating microscope, with the exoscope's shared surgical view possessing obvious educational and workflow advantages. Further clinical trials are justified to validate this initial cadaveric experience. Exoscope, Operating microscope, Microneurosurgery, Stereopsis ABBREVIATIONS ABBREVIATIONS 2-D 2-dimensional LBL line-by-line OM operating microscope OR operating room The introduction and utilization of the operative microscope had a profound impact on operative technique and neurosurgical care. More recently, neurosurgeons have adopted the use of telescope-based surgery (ie, endoscopy) and broadened its application. Endoscopy in other surgical disciplines offered improvements in surgeon comfort, decreased fatigue, and decreased operative morbidity.1-7 Due to confined operative corridors in cranial surgery, smaller diameter scopes are required for most neurosurgical procedures. Neuroendoscopes therefore have shorter focal distances and require closer positioning to the focal point. These technical constraints translate into increased difficulty maneuvering instruments around the scope and frequent obstruction of the lens by blood and tissue. These surgical workflow issues ultimately limit neurosurgical application of endoscopy. In response to the limitations of both the endoscope and operative microscope, a high-definition extracorporeal telescope (“Exoscope”) system was developed over the past decade.7,8 Previously described exoscope systems (HDXO-SCOPE, VITOM) consisted of a telescope with a mean focal distance of 20 to 30 cm, fiberoptic light source, camera head, pneumatic scope holder, and a high-definition video display. Compared to the endoscope, the exoscope has a wider field of view (600 vs 25 mm) and greater mean focal distance (200-300 vs 3-20 mm), permitting the passage of standard neurosurgical instruments with relative ease. In addition, unlike the operative microscope, the exoscope is light and compact (650 g vs 100 kg), and much less expensive. Furthermore, the exoscope system not only allows both the surgeon and assistant to operate while viewing conveniently positioned high-definition video monitors, but it also allows the rest of operating room (OR) team to follow the procedure with ease. One of the major limitations and criticisms of the prior exoscope system was the lack of stereopsis, as compared with the operating microscope(OM). In response, a 3-dimensional (3-D) 4K-HD exoscope system has been developed to optimize surgical visualization, while maintaining the ergonomic advantage and maneuverability that the exoscope affords. Given the emerging nature of this technology, previous evaluations of exoscopes in neurosurgery are limited to the initial laboratory and clinical experiences with the 2-D exoscopes.7-9 We build upon this work by describing our experience with the novel 3-D 4K-HD exoscope system on a series of human cadaveric specimens. METHODS General Features of the Exoscope System The 3-D video exoscope (Sony Olympus Medical Solutions, Inc, Tokyo, Japan) consists of right and left complementary metal-oxide semiconductor cameras. Both cameras have a resolution of 3840 × 2160 pixels. The system output is in line-by-line (LBL) mode 3-D and can be displayed on 3-D compatible monitors. The cameras are mounted on a proprietary counterbalance arm operated by a traditional dead man switch. The dead man switch, focus, and zoom controls are all located on the camera body. Additional settings are controlled at the console to which the exoscope and counter balance arm are mounted. The system runs on a proprietary Unix-like operating system with a graphical user interface controlled by a touch screen at the console. The light source is a fiber optic LED source. The monitor used in conjunction with this exoscope is a 3840 × 2160 resolution prototype monitor which utilizes the 3-D LBL output of the system to display full-resolution circularly polarized passive 3-D images. Circular polarization 3-D lenses are required to proper viewing of the images. The exoscope has seamless optical and digital zooming that is controlled by either a hand or foot switch. Total magnification ranges from 1.1 to 25.8× with a zooming ratio of 1 to 12 × (6 × optical and 2 × digital). The focal length of the exoscope is 220 to 550 mm, with focusing controlled by hand at the exoscope headpiece or by use of foot pedal. Field of view ranges from 7.5 to 171 mm. Cadaveric Microdissections Seven neurosurgeons with varying experience (ranging from junior resident to senior clinical professor) performed a series of 5 cranial exposures and brain dissections on injected human cadaveric specimens. Each exposure was performed simultaneously on separate specimens utilizing both the 3-D 4K-HD exoscope system and a standard operative microscope (Leica, M320 F12, Leica Microsystems, Wetzler, Germany). The 5 surgical approaches and goals of each exposure are described below. Frontotemporal Orbitozygomatic A curvilinear incision was made from approximately 3 cm inferior to the zygoma to just short of the contralateral midpupillary line. The scalp and superficial temporalis fascia were reflected anteriorly. The temporalis muscle was incised along the superior temporal line and mobilized posteroinferiorly. The periorbital was then bluntly dissected from the bone, starting at the lateral orbital rim and continuing along the superior orbital rim medially to the supraorbital notch. McCarty (fronto-orbital) and temporal burr holes were drilled, and the bony cuts for a 1-piece frontotemporal orbitozygomatic craniotomy10 were performed. Additional removal of the sphenoid ridge and the temporal bone were performed until flush with the posterior orbital wall and floor of the middle fossa, respectively. Next, the dura was opened in a curvilinear fashion and hinged anteriorly. The sylvian fissure was identified and opened from lateral to medial with sharp dissection without retraction. The optic nerve was then identified and the arachnoid of the opticocarotid cistern was opened sharply. Microdissection continued without the utilization of a retractor system, with the aim to identify the following major structures: ipsilateral and contralateral optic nerves, optic chiasm, lamina terminalis, internal carotid artery, anterior cerebral artery, anterior communicating artery, middle cerebral artery, posterior communicating artery, basilar artery, and oculomotor nerve. Retromastoid A curved retromastoid skin incision was made positioned 3 cm medial to the ear and extending from the top of the ear to the mastoid tip. A craniectomy was then performed extending from the transverse sinus superiorly to the foramen magnum inferiorly. The dura was incised parallel to the transverse and sigmoid sinus. A self-retaining retractor was positioned on the lateral cerebellum and flocculus for increased visualization. The arachnoid overlying the cranial nerves and posterior fossa vessels was opened. Microdissection continued with the aim to identify the following major structures: CN IV-XII, internal auditory canal, jugular foramen, hypoglossal canal, vertebral artery, posterior inferior cerebellar artery, anterior inferior cerebellar artery, superior cerebellar artery. Suboccipital A linear skin incision was made extending from the C2 spinous process to 2 cm above the inion. A midline craniectomy was then performed extending from the foramen magnum to just below the transverse sinus. A Y-shaped dural opening was subsequently created, with retraction of the dural flaps superiorly and laterally. Self-retaining retractors were then utilized to separate both cerebellar tonsils, and the overlying arachnoid incised. Microdissection continued with the aim to identify the following major structures: cerebellar tonsils, vermis, bilateral posterior inferior cerebellar arteries, foramen of luschka, obex, floor of the fourth ventricle, and cerebral aqueduct. Supraorbital (Eyebrow) A linear incision was made along the superior border of the eyebrow from the supraorbital notch medially, to 1 cm lateral to the bony edge of the eyebrow. The incision extended through the fascia of the frontalis muscle, exposing the periosteum. The musclulocutaneous layer was retracted anteriorly with hooks. A single McCarty burr hole was placed exposing the periorbita and frontal dura. The first cut of the craniotomy was placed in a curved fashion from the burr hole, turned backwards and superiorly, and brought down just lateral to the supraorbital notch. An osteotome was then used to extend the craniotomy cuts across the orbital bar, and the fronto-orbital bone flap was removed after fracturing across the thin bone of the orbital roof. Next, the dura was opened in a curvilinear fashion and hinged anteriorly. The optic nerve was then identified and the arachnoid of the opticocarotid cistern was opened sharply. Microdissection continued without the utilization of a retractor system, with the aim to identify the following major structures: ipsilateral and contralateral optic nerves, optic chiasm, lamina terminalis, internal carotid artery, anterior cerebral artery, anterior communicating artery, middle cerebral artery, posterior communicating artery, basilar artery, and oculomotor nerve. Interhemispheric Transcallosal A right-sided U-shaped incision was made with the center-positioned anterior to the coronal suture, the hinge positioned laterally, and the apex crossing midline. A pair of burr holes were placed anteriorly and posteriorly straddling the superior sagittal sinus. A bone flap (∼4 × 6 cm) positioned two-thirds anterior and one-third posterior to the coronal suture was cut with the craniotome. The dura was opened in a U-shaped fashion and hinged toward the sagittal sinus. Self-retaining retractors were placed along the frontal lobe laterally, and the falx and sagittal sinus medially, to expand our corridor. We continued to deepen the exposure until the callosomarginal and pericollosal arteries were identified. Next, the body of the corpus callosum was identified and a 3-cm callosotomy was performed. Once the lateral ventricle was entered, the following structures were identified: septal vein, caudate vein, thalamostriate vein, foramen of monro, choroid plexus, fornix, and thalamus. RESULTS All predetermined structures were visualized using both microscope systems. The 3-D 4K-HD exoscope enabled high-resolution viewing of critical neuroanatomic landmarks across multiple cranial approaches (Figures 1-4). The dissections demonstrated in Figures 1 to 4 were completed by senior faculty and chief residents. In comparing the 2 systems, there was no difference in time to dissect and visualize the predetermined anatomic structures. More specifically, utilizing both the standard microscope and the exoscope all dissections were completed in a 25-min period. Craniotomies were not performed with use of either microscope system, as the microscopes were not utilized until opening of the dura. Two surgeons were able to operate simultaneously on the cadaveric specimen utilizing the exoscope. Instead of viewing through a binocular microscope, both operators viewed the 3-D monitor utilizing the 3-D glasses (see Figure 5). The primary and assisting surgeon had the same operating orientation and vantage point. As shown in the figure, the low-profile design of the exoscope easily allowed for both surgeons to view the monitor without obstruction. Additionally, the low-profile design allowed for larger operating corridors, enhanced instrument maneuverability, and less obstruction when passing of instruments compared to the traditional microscope. Video quality of the exoscope was rated excellent by all surgeons, and judged superior when compared with the traditional microscope. This was based on a simple video quality rating scale, which was assessed by 8 reviewers, specifically 5 faculty and 3 residents. Video quality was rated as inadequate, adequate, above average, or excellent. Additionally, because of the size of the 3-D monitor, the operating experience was as immersive as traditional binocular microscopes with oculars directly in front of the surgeon's eyes. FIGURE 1. View largeDownload slide Supraorbital approach via eyebrow incision, right side. Multiple images (A-D) from the 3-D 4K-HD exoscope demonstrating high-resolution views of critical neuroanatomic structures of the supraorbital approach. ON, optic nerve; OC, optic chiasm; CA, internal carotid artery; PCommA, posterior communicating artery; SHA, superior hypophyseal artery; HA, recurrent artery of Heubner; A1, A1 segment of anterior cerebral artery; AChA, anterior choroidal artery; BA, basilar artery; BT, basilar tip; P1, P1 segment of posterior cerebral artery. FIGURE 1. View largeDownload slide Supraorbital approach via eyebrow incision, right side. Multiple images (A-D) from the 3-D 4K-HD exoscope demonstrating high-resolution views of critical neuroanatomic structures of the supraorbital approach. ON, optic nerve; OC, optic chiasm; CA, internal carotid artery; PCommA, posterior communicating artery; SHA, superior hypophyseal artery; HA, recurrent artery of Heubner; A1, A1 segment of anterior cerebral artery; AChA, anterior choroidal artery; BA, basilar artery; BT, basilar tip; P1, P1 segment of posterior cerebral artery. FIGURE 2. View largeDownload slide Retrosigmoid approach, left side. Multiple images (A and B) from the 3-D 4K-HD exoscope demonstrating high-resolution views of critical neuroanatomic structures of the retrosigmoid approach. T, tentorium; SCA, superior cerebellar artery, P, pons; PICA, posterior inferior cerebellar artery. FIGURE 2. View largeDownload slide Retrosigmoid approach, left side. Multiple images (A and B) from the 3-D 4K-HD exoscope demonstrating high-resolution views of critical neuroanatomic structures of the retrosigmoid approach. T, tentorium; SCA, superior cerebellar artery, P, pons; PICA, posterior inferior cerebellar artery. FIGURE 3. View largeDownload slide Orbitozygomatic approach, right side. Multiple images (A and B) from the 3-D 4K-HD exoscope demonstrating high-resolution views of critical neuroanatomic structures of the orbitozygomatic approach. ON, optic nerve; OC, optic chiasm; ICA, internal carotid artery; PCommA, posterior communicating artery; A1 segment of anterior cerebral artery; A2 segment of anterior cerebral artery; HA, recurrent artery of Heubner; M3, M3 segment of middle cerebral artery. FIGURE 3. View largeDownload slide Orbitozygomatic approach, right side. Multiple images (A and B) from the 3-D 4K-HD exoscope demonstrating high-resolution views of critical neuroanatomic structures of the orbitozygomatic approach. ON, optic nerve; OC, optic chiasm; ICA, internal carotid artery; PCommA, posterior communicating artery; A1 segment of anterior cerebral artery; A2 segment of anterior cerebral artery; HA, recurrent artery of Heubner; M3, M3 segment of middle cerebral artery. FIGURE 4. View largeDownload slide Interhemispheric transcallosal approach, right side. Multiple images (A and B) from the 3-D 4K-HD exoscope demonstrating high-resolution views of critical neuroanatomic structures of the interhemispheric approach. F, falx; CC, corpus callosum; PcA, Pericallosal artery. FIGURE 4. View largeDownload slide Interhemispheric transcallosal approach, right side. Multiple images (A and B) from the 3-D 4K-HD exoscope demonstrating high-resolution views of critical neuroanatomic structures of the interhemispheric approach. F, falx; CC, corpus callosum; PcA, Pericallosal artery. FIGURE 5. View largeDownload slide Operative ergonomics of the 3-D 4K-HD exoscope. Image of the operative setup of the 3-D 4K-HD exoscope, demonstrating how 2 surgeons are able to operate simultaneously with a common orientation and vantage point, without obstruction. The low-profile design also allows for large operative corridors and easy maneuverability. FIGURE 5. View largeDownload slide Operative ergonomics of the 3-D 4K-HD exoscope. Image of the operative setup of the 3-D 4K-HD exoscope, demonstrating how 2 surgeons are able to operate simultaneously with a common orientation and vantage point, without obstruction. The low-profile design also allows for large operative corridors and easy maneuverability. The learning curve for the novel exoscope was minimal. All operators became facile with the device after a few minutes of use and a brief instruction tutorial. Junior residents utilizing the exoscope rated the device as simple to use with intuitive controls. When compared to standard operative microscopes, junior residents stated that the simplicity of the exoscope reduced the learning curve. All users completed a rating scale assessment of the exoscope utilizing a simple scale of less complex, equivalent, or more complex as compared to standard operative microscopes. All residents rated the device as less complex. Three of the faculty rated the exoscope as less complex compared to standard operative microscopes and 2 rated it as equivalent. Factors that simplify operative use are fewer operational buttons, point and view operability, smaller overall size, and no eyepiece adjustment. The trigger release, zoom, and focus buttons could all be controlled single handedly (see Figure 6). This simplicity resulted in enhanced operative efficiency when compared to the traditional microscope. Because the exoscope is a single module instead of 1 with 2 handles for control, surgeons found repositioning of the scope easier than traditional microscopes. Factors attributed to ease of repositioning included single hand repositioning, no balancing required, point and view dynamics without necessitating eyepiece repositioning, and compact overall size of exoscope (see Figures 5 and 6). FIGURE 6. View largeDownload slide Focus and zoom adjustment of the exoscope. Adjustment of the zoom and operative focus are controlled from the headpiece of the exoscope utilizing single-handed controls shown. Zoom and focus can also be adjusted with a foot pedal (not shown), allowing for continued bimanual operating during operative view adjustment. FIGURE 6. View largeDownload slide Focus and zoom adjustment of the exoscope. Adjustment of the zoom and operative focus are controlled from the headpiece of the exoscope utilizing single-handed controls shown. Zoom and focus can also be adjusted with a foot pedal (not shown), allowing for continued bimanual operating during operative view adjustment. Ergonomically, the exoscope allowed surgeons to operate in a neutral position, viewing the operative monitor positioned anterior to the surgical field. The monitor could be moved depending on surgical procedure and patient positioning. This benefit of the exoscope became most obvious during the suboccipital and retrosigmoid surgeries. During these approaches, the exoscope was aimed rostrally and upward, similar to traditional microscopes utilized during these procedures. However, because the monitor remained anterior to the surgeon, the surgeon maintained a neutral position while operating. In comparison, when utilizing the traditional microscope, the surgeon positioned themselves low with an upward viewing angle to accommodate the position of the microscope oculars. These ergonomic benefits of the exoscope were especially advantageous during longer surgical dissections. From an educational standpoint, the exoscope provided observers, residents, and students with the same surgical view as the primary surgeon on the 3-D high-definition monitor. Although difficult to quantitatively assess, junior residents stated that as observers their learning was enhanced because of the universal primary surgeon view. Additionally, the low profile of the exoscope allowed observers to better view the primary surgeon's instrument handling, hand/arm positioning, and overall orientation to the operative field as compared to traditional microscopes. All these factors provided an enhanced learning environment and when compared to the traditional microscope, this was an obvious educational benefit. DISCUSSION The 3-D 4K-HD exoscope trialed herein has a number of advantages for neurosurgical applications over traditional OM and endoscopic systems. As detailed in the reviews of prior, 2-D iterations of exoscopes,7,8 it is critical to differentiate this platform from endoscopy before comparing its performance to the OM, which it more closely resembles. Neuroendoscopes utilize long, narrow-diameter rod lenses with short focal lengths and ‘direct in-line’ visual trajectories, resulting in a relatively fixed, narrow field of view that is easily obscured with the introduction of surgical instruments or with moderate to brisk bleeding.7 Endoscopes also traditionally provide only a 2-D image of the surgical field. Given these limitations, neuroendoscopes have been mainly utilized only for niche operations in neurosurgery, such as transsphenoidal, endonasal skull base, or intraventricular procedures.7 Recently developed image-guided endoscopic systems have the potential to improve surgical precision and outcomes with this approach,11,12 but are subject to the same fundamental limitations as traditional endoscopy. In contrast, the 3-D 4K-HD exoscope has a longer focal length that allows it to be positioned outside of the surgical site. This results in a wider visual field that is not as easily obscured by blood or surgical instruments, and closely resembles the view surgeons are accustomed to with the OM. Unlike the OM, however, which provides only the primary surgeon with the highest quality stereoscopic image, the 3-D 4K-HD exoscope provides the same high-quality, 3-D immersive image to the entire OR. This visual arrangement is ideally suited for teaching hospitals as it facilitates resident and fellow education, and may also streamline OR work flow by allowing technicians and OR support staff to be more engaged in the procedure and better anticipate surgeon needs. The 3-D 4K-HD exoscope has a number of other advantages over the OM. First, the exoscope is lightweight and compact, making it easy to move into and out of the OR, and drape before bringing it into the sterile field. This is in stark contrast to the bulky traditional OM, which needs to be wheeled into and out of the OR with each procedure, and takes up significant floor space when in the OR. The 3-D 4K-HD exoscope is also easily positioned and repositioned throughout a case (addressing a criticism of prior exoscope iterations),7 and like previous versions has favorable ergonomics that allow the surgeon to sit in a natural position with their head upright.9 The exoscope also has a large depth of field, which reduces the need for refocusing during periods of dissection. These characteristics are critical to surgeon comfort in long cases, and limit the potential for fatigue and distractions from suboptimal positioning and/or out of focus surgical fields that are often encountered with the traditional OM. Finally, the cost of the exoscope system, including the 3-D monitor, glasses, and service and maintenance will be competitive with respect to the OM, a critical advantage in the increasingly cost-conscious healthcare environment. These combined features make the exoscope appealing for integration into the most cutting-edge neurosurgical programs, with the favorable economics and the portability of the system also facilitating access to this technology in developing countries with more limited resources.7 As with all new technology, there are certain disadvantages. The exoscope arm can obstruct the view of the operators or observers; however, this can be avoided with simple surgeon or exoscope position changes. Additionally, the exoscope relies on an external monitor, which is an added piece of equipment that must be accounted for in the operating suite and during nonuse. This requires knowledge of set up and space within the OR for viewing. No adverse effects such as vertigo or dizziness from wearing the 3-D glasses were reported. Limitations This study is the first neurosurgical experience with the 3-D 4K-HD exoscope, and while it convincingly demonstrated a comparable visual experience to the OM during cadaver dissections, its performance in living-patient surgery remains to be evaluated. The authors nonetheless feel that the advantages of the 3D 4K-HD exoscope noted in this trial, including ease of scope positioning, surgeon ergonomics, and a communal, immersive, high-resolution viewing experience, will only be amplified in a live OR setting. As future evaluations occur and surgeon exposure to this system increases, the authors predict that integration of this system into neurosurgery, and other fields utilizing surgical microscopy, will rapidly occur. CONCLUSION The 3-D 4K-HD is a novel exoscope system aimed at improving visualization and overall operative experience of the surgeon and entire surgical team. Visualization, ergonomics, and maneuverability all favored the exoscope system over the traditional microscope in this small series of cadaveric dissections, thereby supporting a proof of concept for this operative system. Our trial supports a planned clinical use assessment during human neurosurgery to validate this initial cadaveric experience. Disclosure Laboratory time for this work was supported by an unrestricted gift from Sony Olympus Medical Solutions, Inc (Tokyo, Japan). REFERENCES 1. Quilici PJ, Greaney EM, Quilici J, Anderson S. Laparoscopic inguinal hernia repair results: 131 cases. Am Surg . 1993; 59( 12): 824- 830. Google Scholar PubMed  2. Cruvinel MG, Duarte JB, Castro CH, Costa JR, Kux P. Multimodal approach to rapid discharge after endoscopic thoracic sympathectomy. Acta Anaesthesiol Scand . 2005; 49( 2): 238- 242. Google Scholar CrossRef Search ADS PubMed  3. McKenna RJ, Mahtabifard A, Pickens A, Kusuanco D, Fuller CB. Fast-tracking after video-assisted thoracoscopic surgery lobectomy, segmentectomy, and pneumonectomy. Ann Thorac Surg . 2007; 84( 5): 1663- 1667; discussion 1667-1668. Google Scholar CrossRef Search ADS PubMed  4. Bilimoria KY, Bentrem DJ, Merkow RP et al.   Laparoscopic-assisted vs. open colectomy for cancer: comparison of short-term outcomes from 121 hospitals. J Gastrointest Surg . 2008; 12( 11): 2001- 2009. Google Scholar CrossRef Search ADS PubMed  5. Shah SS, DiCristina CM, Bell LM, Ten Have T, Metlay JP. Primary early thoracoscopy and reduction in length of hospital stay and additional procedures among children with complicated pneumonia: results of a multicenter retrospective cohort study. Arch Pediatr Adolesc Med . 2008; 162( 7): 675- 681. Google Scholar CrossRef Search ADS PubMed  6. Tiberio GA, Baiocchi GL, Arru L et al.   Prospective randomized comparison of laparoscopic versus open adrenalectomy for sporadic pheochromocytoma. Surg Endosc . 2008; 22( 6): 1435- 1439. Google Scholar CrossRef Search ADS PubMed  7. Mamelak AN, Nobuto T, Berci G. Initial clinical experience with a high-definition exoscope system for microneurosurgery. Neurosurgery . 2010; 67( 2): 476- 483. Google Scholar CrossRef Search ADS PubMed  8. Mamelak AN, Danielpour M, Black KL, Hagike M, Berci G. A high-definition exoscope system for neurosurgery and other microsurgical disciplines: preliminary report. Surg Innov . 2008; 15( 1): 38- 46. Google Scholar CrossRef Search ADS PubMed  9. Mamelak AN, Drazin D, Shirzadi A, Black KL, Berci G. Infratentorial supracerebellar resection of a pineal tumor using a high definition video exoscope (VITOM®). J Clin Neurosci . 2012; 19( 2): 306- 309. Google Scholar CrossRef Search ADS PubMed  10. Andaluz N, van Loveren HR, Keller JT, Zuccarello M. The one-piece orbitopterional approach. Skull Base . 2003; 13( 4): 241- 245. Google Scholar CrossRef Search ADS PubMed  11. Spiotta AM, Fiorella D, Vargas J et al.   Initial multicenter technical experience with the Apollo device for minimally invasive intracerebral hematoma evacuation. Neurosurgery . 2015; 11( suppl 2): 243- 251; discussion 251. Google Scholar CrossRef Search ADS PubMed  12. Fiorella D, Gutman F, Woo H, Arthur A, Aranguren R, Davis R. Minimally invasive evacuation of parenchymal and ventricular hemorrhage using the Apollo system with simultaneous neuronavigation, neuroendoscopy and active monitoring with cone beam CT. J Neurointerv Surg . 2015; 7( 10): 752- 757. Google Scholar CrossRef Search ADS PubMed  COMMENT The authors summarize their initial experience with a new 3-D 4K-HD exoscope. The technology they describe appears to offer a new set of advantages over the traditional operating microscope, including maneuverability and ergonomics. This preliminary experience in cadaveric dissections provides optimism that functionally it performs at least as well as the traditional microscope. Certainly, further evaluation must be done in living patients and with a larger group of surgeons to fully identify the advantages and disadvantages of this new tool. New tools like this one help identify areas where our current technology lacks. Future, more widespread, attempts with this device will help to show whether it offers enough to become a more integral tool in the neurosurgeon's armamentarium. Rohan Chitale Nashville, Tennessee Copyright © 2017 by the Congress of Neurological Surgeons

Journal

Operative NeurosurgeryOxford University Press

Published: Apr 1, 2018

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