Discussion
Endoscopic sinus surgery is considered the gold standard for the management of most sinus pathology. Improvements and updates in image quality and angled scopes have resulted in advances in endoscopic sinus surgery (ESS) with the expansion of use of the endoscopic approach in skull base surgical interventions.(10)
The three dimensional (3D) endoscopes have been utilized for endonasal surgery, and recent publications have shown the advantages and a number of limitations in using 3D endoscopes in endonasal sinus surgery or skull base surgical approaches.(2) In these reports, 3D images were reconstructed from multiple 2D images obtained using special lenses that imitate the compound eye of bees, from various angles.(11) This is a different technology to the 3D HD storz endoscopes that were used in this study.
In our clinical study, the mean operative time in the 2D group was significantly higher than the 3D group. This is also shown by Castelnuovo et al., (2012), while studying the utilization of the 3D endoscope in resection of anterior skull base malignancy, they found a statistically significant reduction of both operative time and error rates by using the new stereoscopic endoscope(12), which require the passive polarizing three dimensional display(13) compared to two dimensional endoscope. Also they recorded low(14) or absent surgeon discomforts with the novel stereoscopic systems.(15) Moreover Barkhoudarian et al., reported that there is a strong evidence for 3D allowing a 30-minute reduction in pituitary adenoma resection operating time.(16) A shorter operative time decreases the risk of postoperative complications in endoscopic pituitary surgery.(17)
In our study, the frequency of using the surgical navigation system showed that there was a highly significant increase in frequency of navigation system use in the 2D group more than the 3D group. There are no similar studies in the literature to compare to our study but these results are in keeping with the hypothesis that 3D endoscopy gives improved depth of perception hence a reduction in the need to use navigation to confirm anatomy.
In our 2D group there was no surgeon discomfort during all operative cases while 3 operative cases in the 3D group resulted in the surgeon reporting discomfort (headache/migraine); there was no significant difference between the two studied groups. Other authors in clinical and experimental studies reported similar results. Moreover a small number of surgeons in multiple studies recorded user side effects and discomforts like dizziness, eye strain, fatigue, migraine and headaches in 3D endoscope users.(18)
Minimally invasive surgery is the standard of patient care in many institutions (19). However, incidents of increased complication rates among inexperienced surgeons have been reported and a detailed study of these claims demonstrates that the surgical learning curve plays a vital role in the rate of complications.(20)
Regarding intraoperative complications, the incidence of complication in our 2D group was higher than 3D group, however it was statistically not significant. The most common complication in our 2D group was cavernous bleeding in 11 cases (42.3%) followed by C.S.F leak in 6 patients (23.1%), while in 3D group there were 7 cases of C.S.F leak (26.9%) followed by cavernous bleeding in 5 patients (19.2%).
For endoscopic pituitary surgery, the Southern Surgeons club noted that 90% of complications happened in the first 30 patients of the learning curve, with the initial risk being tenfold of that after 50 operations.(21) They were using 2D endoscopy and a number of explanations were given including: loss of depth perception (stereopsis), ergonomic difficulties of using an endoscope, and issues with training.(20, 21)
Regarding our cadaveric study, the mean dissection time for both sides of the cadavers using 2D endoscope was 19.67±1.53 minutes while in using 3D endoscope was 21.33±4.93 minutes which was not statistically significant (p > 0.05). It is possible that if we had chosen a more complicated index longer operation to compare then we might increase the likelihood of repeating the same results as seen in the clinical study with 2D taking longer than 3D.
The cadaveric study describes only a qualitative comparison of various approaches and anatomical landmarks using 3-dimensional endoscopy as a new learning tool and technique. Future studies should focus on more detailed quantitative comparisons of field exposure and surgical limitations.