Abstract
The aim of this study is to assess field of view, usability and applicability of a rigid, multidirectional steerable video endoscope (EndActive) in various intracranial regions relevant to neurosurgical practice. In four cadaveric specimens, frontolateral, pterional, transnasal (to sella and clivus), interhemispheric (transcallosal and retrocallosal) and retrosigmoid approaches as well as precoronal burr holes for ventriculoscopy were performed. Anatomical target structures were defined in each region. We assessed field of view as well as optical and ergonomic features of the prototype. The EndActive is a 4-mm-diameter rigid video (endo)scope with an integral image sensor comprising an embedded light source. The viewing direction in a range of 160° can either be controlled by the computer keyboard or a four-way joystick mounted to the handle section of the endoscope. The endoscopic imaging system allows the operator to simultaneously see both a 160° wide-angle view of the site and an inset of a specific region of interest. The surgeon can hold the device like a microsurgical instrument in one hand and control movements precisely due to its reduced weight and ergonomic shape. The multiplanar variable-view rigid endoscope proved to be useful for following anatomical structures (cranial nerves I–XII). The device is effective in narrow working spaces where movements jeopardize the delicate surrounding structures. The multiplanar variable viewing mechanism in a compact device offers advantages in terms of safety and ergonomics. Improving the usability will probably optimize the applicability of endoscopic techniques in neurosurgery.
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Cappabianca P, Cinalli G, Gangemi M, Brunori A, Cavallo LM, de Divitiis E, Decq P, Delitala A, Di Rocco F, Frazee J, Godano U, Grotenhuis A, Longatti P, Mascari C, Nishihara T, Oi S, Rekate H, Schroeder HW, Souweidane MM, Spennato P, Tamburrini G, Teo C, Warf B, Zymberg ST (2008) Application of neuroendoscopy to intraventricular lesions. Neurosurgery 62:575–597
Ebner FH, Marquardt JS, Hirt B, Feigl GC, Tatagiba M, Schuhmann MU (2010) Broadening horizons of neuroendoscopy with a variable-view rigid endoscope: an anatomical study. Eur J Surg Oncol 36:195–200
Fries G, Perneczky A (1998) Endoscope-assisted brain surgery: part 2—analysis of 380 procedures. Neurosurgery 42:226–231
Hopf NJ, Perneczky A (1998) Endoscopic neurosurgery and endoscope-assisted microneurosurgery for the treatment of intracranial cysts. Neurosurgery 43:1330–1336
Mayberg MR, LaPresto E, Cunningham EJ (2005) Image-guided endoscopy: description of technique and potential applications. Neurosurg Focus 9:E10
Perneczky A, Fries G (1998) Endoscope-assisted brain surgery: part 1—evolution, basic concept, and current technique. Neurosurgery 42:219–224
Prevedello DM, Doglietto F, Jane JA Jr, Jagannathan J, Han J, Laws ER Jr (2007) History of endoscopic skull base surgery: its evolution and current reality. J Neurosurg 107:206–213
Renn WH, Rhoton AL Jr (1975) Microsurgical anatomy of the sellar region. J Neurosurg 43(3):288–298
Rhoton AL Jr (2000) The cerebellopontine angle and posterior fossa cranial nerves by the retrosigmoid approach. Neurosurgery 47(3):93–129
Schroeder HW, Nehlsen M (2009) Value of high-definition imaging in neuroendoscopy. Neurosurg Rev 32:303–308
Snyderman CH, Carrau RL, Kassam AB, Zanation A, Prevedello D, Gardner P, Mintz A (2008) Endoscopic skull base surgery: principles of endonasal oncological surgery. J Surg Oncol 97:658–664
Tabaee A, Anand VK, Barron Y, Hiltzik DH, Brown SM, Kacker A, Mazumdar M, Schwartz TH (2009) Endoscopic pituitary surgery: a systematic review and meta-analysis. J Neurosurg 111:545–554
Conflict of interest statement
The present study was sponsored by Karl Storz GmbH, Tuttlingen, Germany on request of the authors with regard to the costs of the anatomical specimens and study. Karl Storz supplied the EndActive for the laboratory investigation. Karl Storz did not influence the study design and collection, analysis and interpretation of data. The decision to submit the manuscript for publication was taken exclusively by the authors, which have no financial and personal relationship to Karl Storz and its representatives.
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Henry W. S. Schroeder, Greifswald, Germany
Ebner et al. evaluated the usefulness of a rigid multidirectional steerable video endoscope (EndActive) provided by Karl Storz GmbH & Co. KG, Tuttlingen, Germany in four human cadaver heads. They assessed the field of view and the applicability in various approaches (frontolateral, pterional, transnasal, interhemispheric and retrosigmoid as well as precoronal burr holes for ventriculoscopy). In contrast to standard rigid endoscopes, the videoscope allows to simultaneously see both a 160° degree wide-angle view of the site and an inset of a specific region of interest. By activating a joystick mounted on the handle of the scope, the surgeon can move the field of view in any of the four available directions (up, down, left and right) within a range of 160°. Because of the variable angles of view which do not require any endoscope movements, the authors state that the use of this endoscope enhances the safety of endoscopic inspection.
This is an interesting report on a novel endoscope. Compared with the traditional rigid rod-lens scopes, it provides several advantages: reduced weight, wide field of view (160°), variable viewing angle, picture-in-picture display, etc. The main advantage is that the tip of the endoscope does not need to be moved to look around. The handling seems to be convenient for the surgeon. However, the main limitation today is the poor resolution of only 320,000 pixels. This is even worse than standard PAL resolution. When comparing it with high-definition (HD) cameras, the resolution is more than six times lower!!! Furthermore, the colour fidelity is obviously much lower than with HD systems as well. I would not accept this decrease in resolution and colour fidelity, although some features are better than in standard rod lenses. Today, HD video cameras are still the state-of-the-art in endoscopic neurosurgery. However, with further improvement of the video chips, video endoscopes will probably replace the “old” rod lenses in the future.
Luigi M. Cavallo, Paolo Cappabianca, Napoli, Italy
In this manuscript, the reader is directly brought into the conceptual thinking of “minimally invasive” so that it can easily be understood that where there is technological progress, there is chance of development, and probably there is a way to miniaturize it. We could intend the miniaturization as a natural path of scientific burst, just wondering that, in 1946, the ENIAC, one of first calculator, occupied an entire room and weighted 30 t. Nowadays, there have been developing machines that dispose of calculating capabilities million-fold superior, with surprisingly reduced dimensions, down to a fingertip. The endoscopic equipment perfectly fits this environment, being the result of an integrated clock gear mechanism between different electronic devices changing through time and technological progress.
The actual frontier is represented by the use of HD cameras that provide an extremely sharp and active vision, almost overcoming the lack of tridimensionality. Nevertheless, these HD cameras’ weight of more than 400 g is really too much as compared with the 70 g of the system developed by authors, which measures 18 cm of total length (10 cm the shaft and 8 the handle). Conversely, the quality of images, made of only 320,000 pixels, is not yet an adequate advantage as compared to the 2 million-pixels image quality of the HD cameras, as also admitted by the authors, who had to use a small-sized image to avoid a blurring effect.
However, they demonstrated an excellent versatility of the rigid multidirectional steerable video endoscope (EndActive), applying it in lab rehearsals of different neurosurgical procedures. We found the possibility of controlling viewing direction by means of a remote computer keyboard or directly with a four-way joystick very attractive. Above all, the multiplanar variable view provided, thanks to the camera–chip unit on the tip of the endoscope, a wider lens that gives a 160° range of view (for the conventional scopes, it is 80°) and the inclination sensor as an extra feature have to be highlighted.
Therefore, we retain that the authors are definitely on the right path; it is only a matter of time before realising a new device with the same image quality of HD cameras but with the same weight, shape, ergonomics and manoeuverability of a pencil. No doubt that this possibility will change the endoscope use and applications in neurosurgery.
Dieter Hellwig, Hannover, Germany
The authors describe a newly developed prototype of a rigid, multidirectional steerable video endoscope which they use for cadaveric research. In contrast to other available neuroendoscopes, this videoscope has no working channel and can be used as a complementary tool during microsurgical interventions or for ventriculoscopy. The instrument could be very helpful to visualise spaces, which cannot be inspected using the microscope for instance in aneurysm surgery or microvascular decompression as well as for other skull-base interventions. Furthermore, the reduced weight and the ergonomic shape make it easy to handle like any other microsurgical instrument.
In conclusion, the rigid multidirectional steerable videoscope represents a useful contribution to endoscopy-assisted microsurgery. We are eager to see the first results after the application in neurosurgery.
Nikolai Hopf, Stuttgart, Germany
The paper of Ebner et al. on “Developments in neuroendoscopy: trial of a miniature rigid endoscope with a multidirectional steerable tip camera in the anatomical lab” is a well written and important contribution to the literature. The idea to overcome the restrictions of classic endoscopes which is either to be rigid or steerable in multiple viewing directions is an important step for neuroendoscopy to play an important role in the daily neurosurgical routine, may be, sometimes even as the most important visualisation tool. The most important advantage of the system is the ability to change viewing angles without changing the endoscope or moving it at all. In addition, the light weight, by providing a chip at the tip and no heavy camera at the end of the optic, is a promising although not a new technique. However, the used prototype has also some major restrictions. Most importantly, it has no HD resolution, and it is not designed to be fixed in the operating field to use bimanual endoscope-controlled microsurgical technique. It is also not yet clear how robust the mechanical parts on the tip of the system really are and if sterilization may be an issue when used in patients. These questions were of course not yet addressed in the lab tests but need to be considered in the further development. Furthermore, it needs to be determined whether the assumed advantage of the system to not have to move the endoscope for “looking around” proves to be of importance during surgery. In summary, Ebner at al. have successfully demonstrated that the combination of two putative incompatible characteristics of endoscopes does work in a lab setting, but it is still a long way to go for successful use in patients.
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Ebner, F.H., Marquardt, J.S., Hirt, B. et al. Developments in neuroendoscopy: trial of a miniature rigid endoscope with a multidirectional steerable tip camera in the anatomical lab. Neurosurg Rev 35, 45–51 (2012). https://doi.org/10.1007/s10143-011-0341-6
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DOI: https://doi.org/10.1007/s10143-011-0341-6