Neurol India Home 

Year : 2019  |  Volume : 67  |  Issue : 4  |  Page : 1024--1026

Endoscopic Transsphenoidal Surgery: A Revolutionary Evolution

Dhananjaya I Bhat 
 Department of Neurosurgery, NIMHANS, Bengaluru, Karnataka, India

Correspondence Address:
Dr. Dhananjaya I Bhat
Professor of Neurosurgery, NIMHANS, Hosur Road, Bengaluru - 560 029, Karnataka

How to cite this article:
Bhat DI. Endoscopic Transsphenoidal Surgery: A Revolutionary Evolution.Neurol India 2019;67:1024-1026

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Bhat DI. Endoscopic Transsphenoidal Surgery: A Revolutionary Evolution. Neurol India [serial online] 2019 [cited 2021 Jan 19 ];67:1024-1026
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Full Text

Endoscopes have slowly evolved from a crude contraption called the light conductor, or Lichtleiter, demonstrated by Philipp Bozzini in 1806 consisting of candle with a mirror, eye piece, and a hollow tube to the present highly sophisticated fiber optic cables, based on high fidelity transmission of light abiding the principles of total internal reflection of light.

From more than a century, neurosurgeons have evolved in their management of this indomitable disease: the pituitary adenoma. It started off with Sir Victor Horsley and others in the late 19th century with transcranial surgery for these adenomas. Cushing, Hirsch in the early 20th century popularized the transsphenoidal surgery, which unfortunately went into disrepute due to poor illumination and technical limitations. The world had to wait till the latter half of the 1950s when Guiot (a student of Norman Dott) brought about a resurgence of sublabial transsphenoidal surgery with the use of intraoperative image intensification and fluoroscopy. Later, Jules Hardy (1967) introduced the microscope and for another 2–3 decades this would be the most popular surgery for pituitary adenomas. From the 1960s onwards over the next two decades, there was the development of fiberoptics, camera attachments, along with major technical advances in endoscopes. In the 1980s, with the ENT surgeons performing functional endoscopic sinus surgeries, endoscopic transsphenoidal surgery (ETSS) spawned under the astute hands of neurosurgeons, namely Jankowski, Jho, Cappabianca, and many others in the 1990s. Initially, it was endoscope-assisted microscopic surgery, which soon transformed into purely endoscopic surgery. Thus dawned a new era of pituitary surgery.[1]

Man's insatiable thirst for the quest of perfection and the ideal surgery has always been bolstered by the parallel advances in the field of technology. ETSS is one of the paragons for this statement. For any new innovation to be successfully and widely adopted, certain criteria need to be fulfilled, and again, ETSS exemplifies it.[2] These features include the following:

Limitations of available techniques: Microsurgical pituitary surgery results were the best in the 1990s and surgical perfection had been achieved. However, microscopes provided a tunnel view restricted to the midline by the retractors, so lateral and suprasellar lesions were difficult to visualize. Nasal complication from stripping of mucosa was evident. Endoscope helps in circumventing all the above. In 1990s ENT surgeons perfected the art of endoscopic sinus surgery and could easily visualize the sphenoid sinus. This led to the growth of ETSS with better maneuverability, wide panoramic view, and lesser damage to mucosa [1],[3],[4]Tangible benefits over the existing time-honored procedures: Adoption of any new technique, especially in medicine, must undergo the robust test of fire and come out unscathed for it to be accepted in the highly skeptical bordering to neurosis medical fraternity, many of whom believe status quo as best. In this effect, a large body of evidence in the form of publications and conference presentations have appeared. What was the final verdict? The superiority of endoscopy over microsurgery has not been unequivocally established. Notwithstanding this, it can be concluded that endoscopic surgery is not inferior if not superior to traditional microsurgery. Pablo et al. in their article published in this issue of Neurology India “Endoscopic versus microscopic pituitary adenoma surgery, a single-center study,” studied the outcome of 399 patients who had undergone either microscopic or endoscopic surgery for pituitary adenomas.[5] Their results were similar to that reported in the literature. Their study and many other studies have shown lesser invasivity and mucosal complications; better gross tumor resection for invasive tumors especially in lesions with suprasellar and cavernous sinus extensions; lesser cerebrospinal fluid leaks; and shorter hospital stay with ETSS as compared to microscopic transsphenoidal surgeries. There was no change in the overall outcome, visual outcome, or endocrine remissions in majority of the studies. Only one meta-analysis confirmed significant vascular injury following endoscopic surgeries [3],[6],[7],[8],[9]The procedure should not be a major paradigm shift from the existing surgical techniques, thus making learning easier. The procedure should be visualized by the observing surgeon while it is being performed. It is very difficult for a person to come out of his comfort zone and try a new difficult technique, especially with the present legally oriented public. ETSS satisfies all these preconditionsThere should be an adequate caseload to justify learning and shift to a new surgical procedure. Pituitary adenoma constitutes one of the most common central nervous system tumors managed by a neurosurgeon, a reason enough to learn an apparently better techniquePatients demanding the surgical approach. Patients are allured by the terms “minimally invasive,” “endoscopic” as opposed to “open or microscopic” surgery. Let us be clear that in these days of heightened patient awareness, widespread availability of a wealth of information from the internet, the veracity of which cannot always be vouched for, it becomes all the more reason for the competitive neurosurgeon to be abreast with the latest know-how in the professional frontDriving force of market and training programs. Endoscope manufacturing companies are aggressively marketing their products, highlighting the obvious selective advantages of their equipment to both the professionals and to general public. A large number of training programs organized by them on a regular basis throughout the world has seen a slow steady diffusion of the technology on this planet. In a web-based multicenter worldwide questionnaire to pituitary surgeons, it was seen that the majority (85.2%) of cases were endoscopically approached.[10]

One interesting terminology frequently encountered in the technique of ETSS or any other endoscopic surgery for that matter is “learning curve.”[4],[8],[9] Learning curve was used in the aeronautical manufacturing company in 1936 by TP Wright to explain the fact that – as experience in producing a particular airplane part increases – the time taken and the cost to manufacture that product decreases; i.e. as you become more experienced you do the work faster and more efficiently.[11] This word has been imbued into the surgical arena during the 1980s with the introduction of the term “minimally invasive surgery” (coined by the English urologist John Wicker). In layman's term, it is the time taken or the number of procedures to be performed by an average surgeon before he/she can deliver acceptable clinical outcomes. Graphical representation of this gives a learning curve. A superfluous explanation is: the X-axis of the graph represents a number of surgeries performed or time and Y-axis the increasing proficiency levels. When a new surgical skill is learned, initially there is an upward slope of the curve and after sometime it plateaus, i.e. the surgeon doesn't improve further in surgical adept. In endoscopic pituitary surgery this term “learning curve,” especially “steep learning curve,” has been used in gay abandon. Also, it particularly applies to surgeons who are well trained and experienced in microscopic transsphenoidal pituitary surgery who may contemplate changing to ETSS. The “curves” act as a major deterrent for them. They are so accustomed to a particular type of surgical practice with unequivocal excellent outcomes that learning something new, which is “steep,” unlearning what is imbued in their genes, may appear as a daunting task. The term “steep” may actually be a misnomer.[11] A steep curve indicates that there is an almost vertical take-off in the graph, with surgical proficiency increasing rapidly with a very few cases. However, in literature, “steep” is used to indicate more difficulty, so the correct term may be a “gradual” learning curve. The bright side of this aspect of transition from microscopic surgery to endoscopic is that there is a larger body of evidence which states that experienced surgeons are good in transforming their approach without causing any worsening of clinical outcomes. They need to be patient and bear with initial longer time of surgery, frustration of getting used to the two-dimensional images, difficulty in achieving hemostasis, and getting used to the clutter of instruments in the narrow field. The learning curve for an experienced microscopic surgeon to plateau endoscopic skills is said to vary on an average between 20 and 50 cases.[4],[8],[9],[12] As for an untrained neurosurgical resident, both microscopy and endoscopy are new and he has to acquire the skills by step-wise supervised training programs, cadaver dissection, and attending workshops. In an interesting study, surgically untrained medical students were given a 12-week intensive training in open laparotomy and laparoscopic surgical techniques. At the end of the study, it was found that they were equally trained in both the types with no gross difference in expertise between the two procedures.[13] With the embracement of pure endoscopic surgery by many teaching institutes worldwide, a wealth of pedantic information and workshops, I don't expect to see any unique difficulty for a trainee to excel in endoscopic surgery. The only limitations being the trainee's aptitude, surgical dexterity, and appropriate pedagogy. In few years or decade from now, the word “learning curve” will become obsolete in endoscopic surgery; just like we never hear about “learning curve” for hand/eye coordination for using microscopes in neurosurgery. It becomes part of their training program.

To help surgeons overcome initial difficulties, technology has come to the rescue. There is neuronavigation that reigns in the horse-like blindfolds preventing it to go astray.[4] To overcome the flat two-dimensional images, three-dimensional endoscopes are available, which help in learning and teaching and may improve the surgical results in future.[14] Virtual reality endoscopy is in the nascent stage and helps in training and preoperative planning.[15] The problem of controlling difficult bleeding with endoscopy has been a concern among many surgeons. With improved skill in handling the instruments, patience, and newer hemostatic agents, this problem can be tackled confidently. Along with all these exciting changes going on, with better resolution cameras, vetting of sophisticated instruments, and with the ethos of patient safety, comfort along with best clinical outcomes prime in mind of every dynamic neurosurgeon, endoscopic pituitary surgery may be the next revolutionary evolution in neurosurgery akin to microscopic surgery is seen in the latter half of the 20th century.


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