Combined Exoscopic and Endoscopic Technique for Craniofacial Resection

Round 1

Reviewer 1 Report

Authors anwered to previous remarks and modified the manuscript accordingly

Reviewer 2 Report

In the present form the manuscript appears acceptable. All the concerns have been correctly and extensively addressed.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The paper contains an evaluation of a technique for craniofacial resection using exocscope together with endoscpe to overcome the blond spot limitations.

The paper is very interesting and particularly relevant  for the fies, and the presented material is of very good quality.

I especially appreciated the details about the two specific cases, and the associated figures with clear annotations.

Minor comments:

Scheme in Fig. 1 can be improved by highlighting better the differences between transcranial and transfacial approach.

Additional short details about the procedure can be added in the introduction: many details are found here and there, and they can be organized in a structured way.

What is PORT in Table 1? Post Operative Radio Therapy? Please specify.

Line 145:  (are) summarized. 

In general, the manuscript needs an additional proofread. Too many passive sentences are used, and in some parts the narrative style can be significantly improved.

The inner ear in Fig.3 is not clear: use another color. Same for eustachian tube.

line 188 - 195: the concepts are repeated different times. 

The assessment outcomes are not clear: does the combined exo+endo reduce the time for completing the procedure? It is not evident from Section 3.3

Author Response

Minor comments:

Comment＃1

Scheme in Fig. 1 can be improved by highlighting better the differences between transcranial and transfacial approach.

Response: We appreciate your comment, and have revised Figure 1a accordingly.

Comment＃2

Additional short details about the procedure can be added in the introduction: many details are found here and there, and they can be organized in a structured way.

Response: We appreciate your comment on this point and have revised the introduction as follows:

“In CFR, a transcranial approach is critical in skull base osteotomy to permit the lesion to remain covered in the safety margin at the skull base (Figure 1a red arrow). Although neurosurgeons are generally not very familiar with the management of malignant head and neck tumors, the efficacy and safety of surgical resection are expected to improve with the proactive involvement of neurosurgeons in the treatment of these tumors; hence, neurosurgeons should be a part of the multidisciplinary team.the success rate and safety of surgical resection is expected to improve with their proactive involvement in tumor treatment [8]. CFR requires exceptional surgical skills and anatomical knowledge since critical neural and vascular structures are within or adjacent to the skull base. An optimal view of the surgical field is required for the precise resection of the tumor at the appropriate site. CFR procedures are classified into anterior, lateral, anterolateral, and temporal bone resection (TBR), according to the position of the skull base resection [9].” (Lines 42–59)

“In this report, we describe our initial experience with CEE in the transcranial ap-proach for CFR. It is expected that the introduction of digital visualization devices, such as exoscopes, will lead to major advances in skull base surgery [20], and our experience will be beneficial for surgeons involved in the treatment of malignant head and neck tumors.”(Lines 343-347)

Comment＃3

What is PORT in Table 1? Post Operative Radio Therapy? Please specify.

Response: As per the reviewer’s comment, we have defined the abbreviation as follows:

“PORT, postoperative radiotherapy” (Line 162)

Comment＃4

Line 145: (are) summarized.

Response: We have revised the text as follows:

“Clinical and demographic characteristics for the enrolled patients wereare summarized in Table 1.” (Lines 155–156)

Comment＃5

In general, the manuscript needs an additional proofread. Too many passive sentences are used, and in some parts the narrative style can be significantly improved.

Response: The manuscript has undergone English Language proofreading by a specialized language editing company again.

Comment＃6

The inner ear in Fig.3 is not clear: use another color. Same for eustachian tube.

Response: We appreciate your comment regarding this point and have revised Figure 3e accordingly.

Comment＃7

line 188 - 195: the concepts are repeated different times.

Response: We agree with the reviewer, and have revised the text as follows:

“For temporal bone resection, it was critical to preservinge important structures, such as the internal carotid artery and jugular bulb located on the medial side of the temporal bone, is critical; but however, it was difficult to observingethe medial side of temporal bonethese vital anatomical structures under an exoscope is challenging because since the middle ear and external ear involved in the tumor obstructed the field of view (Figure 3c, green ellipse). Therefore, during the me-dial segment osteotomy, we switched from an exoscope to an endoscope to obtain a better visualization of these vital anatomical structures. aAn endoscope was inserted into the extradural space of the lateral skull base, and the medial segment was transected under direct visualization (Figure 3 e).” (Lines 207–215)

Comment＃8

The assessment outcomes are not clear: does the combined exo+endo reduce the time for completing the procedure? It is not evident from Section 3.3

Response: We agree with your comment that the assessment outcomes are not clear; however, owing to the very small number of cases and wide variety of surgery types, objectively comparing the operation times with previous experience using microsurgery was not possible. We do not think that the combined exo-endo approach can reduce the operation time; however, it enables performing more accurate surgery in the same amount of time, in a better ergonomic condition. We have revised the text to address this, as follows: 

“The mean operation times (total, 811.5±385.1 min; neurosurgery 200.0±56.8 min) and the mean amount of intraoperative blood loss (698.4±512.2 ml) were comparable to those observed in our previous reports on CFR using a microscope (total operation time for TBR, 765.8±139.8 min [28]; neurosurgery operation time for TBR, 161.2±68.5 min [28]; intraoperative blood loss for TBR, 1627.0±1568.7 ml [28]; total operation time for anterolateral CFR, 942 (range, 616–1945) min [7]; and intraoperative blood loss for anterolateral CFR, 1426 (range, 500–6228) ml [7]). Considering the ergonomics and small footprint of the exoscope and endoscope, and the reduction of blind spots by the endoscope, we assume CEE to be better than a microscope for a transcranial approach in CFR.” (Line 368–376)

Reviewer 2 Report

In this interesting work by Iwami K and colleagues the feasibility of a combined exoscopic-endoscopic approach for craniofacial resections was assessed retrospectively in a case series of 8 cases, operated on between 2019 and 2021. The authors found the combined approach of these two instruments as an effective strategy in transcranial skull base surgery, especially in cases where simultaneous surgical procedures were carried on.

As correctly stated by the authors in the introduction section, when managing malignant head/neck cancers, an optimal view of the surgical field is required for the precise resection of the tumor at the appropriate site. In this context in recent years combined craniofacial resections, performed by different specialists, have been proposed as a feasible option in order to increase the extent of tumor resection. In this context, the possibility to couple an exoscopic procedure to the nasal endoscopic one would be welcomed, given the proven very high quality images that modern exoscopes may offer.

The article is interesting and well written. Images are very high quality ones and the authors should be commenced for them. Both exemplificative cases are well depicted and reported. As it appears one of the first studies that directly assessed the feasibility of a combined exoscopic-endoscopic approach in neurosurgery, for sure this work deserves attention.

I would ask minor corrections to the authors:

• english written language may be improved by a mother tongue speaker;
• why did the authors decide to perform the endoscopic part as a single operator procedure and not as a 4-hands procedure?
• The table reporting the eight cases should be enriched specifying the exact location of each tumor and the exact transcranial/transnasal approach performed
• given that only eight cases are reported, the pre and postoperative images of such cases would be welcomed in a figure, for instance eliminating figure 3 that appears unnecessary.

Once revised as suggested, this work may be an appropriate publication for the journal.

Author Response

Comment＃1

English written language may be improved by a mother tongue speaker;

Response: The manuscript has undergone English Language proofreading by a specialized language editing company again.

Comment＃2

why did the authors decide to perform the endoscopic part as a single operator procedure and not as a 4-hands procedure?

Response: When the surgical field becomes deep and narrow, surgical procedures are often performed by a single operator while the assistant concentrates on operating the endoscope as a scopist. However, when the surgical field is wide, the surgical procedure is more efficient in the 4-hands technique under 3D exoscope. To avoid confusion, the following sentence has been deleted.

“The transcranial approach was performed using the one surgeon, two hand technique.” (Lines 125–126)

Comment＃3

The table reporting the eight cases should be enriched specifying the exact location of each tumor and the exact transcranial/transnasal approach performed

We appreciate your comment regarding this point and have revised table 1 accordingly.

Comment＃4

given that only eight cases are reported, the pre and postoperative images of such cases would be welcomed in a figure, for instance eliminating figure 3 that appears unnecessary.

Response: We appreciate the reviewer’s comment regarding this point and have added pre- and postoperative key images of cases 3–8 in Figure 9. However, since Reviewer 1 instructed us to revise Figure 3, we have retained it.

Reviewer 3 Report

Authors describes their preliminary experience in using a combined exoscope-endoscope approach to cranio-facial resection for malignant or invasive tumors. 
Their experience is well presented and their surgical procedure is meticulously described. 
The discussion is limited only to authors' CEE experience in CFR: I would suggest to discuss the result of recent employed CEE for CFR with previous experience microsurgery, and to better highlight the eventual limitation of miscrosurgery and the benefits of exoscopy.

Author Response

Comment＃1

The discussion is limited only to authors' CEE experience in CFR: I would suggest to discuss the result of recent employed CEE for CFR with previous experience microsurgery, and to better highlight the eventual limitation of microsurgery and the benefits of exoscopy.

We agree with your comment and have revised the text to address this as follows:

“As shown in figure 1a, the microscope is large and overhangs the patient's head. Therefore, when a neurosurgeon and head and neck surgeon simultaneously perform surgical procedures, it is necessary to devise the patient's position, the operators’ position, and the arrangement of the other surgical equipment. Moreover, tThe small camera head of the exoscope and endoscope did do not interfere with the surgeon’s access to the surgical field during simultaneous transcranial and transfacial procedures.” (Lines 357–362)

“The mean operation times (total, 811.5±385.1 min; neurosurgery 200.0±56.8 min) and the mean amount of intraoperative blood loss (698.4±512.2 ml) were comparable to those observed in our previous reports on CFR using a microscope (total operation time for TBR, 765.8±139.8 min [28]; neurosurgery operation time for TBR, 161.2±68.5 min [28]; intraoperative blood loss for TBR, 1627.0±1568.7 ml [28]; total operation time for anterolateral CFR, 942 (range, 616–1945) min [7]; and intraoperative blood loss for anterolateral CFR, 1426 (range, 500–6228) ml [7]). Considering the ergonomics and small footprint of the exoscope and endoscope, and the reduction of blind spots by the endoscope, we assume CEE to be better than a microscope for a transcranial approach in CFR.” (Lines 368–376)