Keywords
bibliometrics - citation analysis - exoscopes - neurosurgery - operative microscopes
Introduction
The introduction of operative microscopes (OMs) marked a significant milestone in
microsurgical procedures, serving as a cutting-edge visual enhancement tool. Over
time, continuous advancements in optics, illumination, and integration into computer-assisted
navigation have elevated OMs to the gold standard in microsurgery.[1] However, OMs have inherent limitations including restricted mobility, bulkiness,
limited accessibility, and a confined operative view.[2] Moreover, ergonomic challenges associated with OMs contribute to intraoperative
fatigue and the risk of work-related injuries.[3]
[4]
In recent years, a paradigm shift has occurred with the introduction of exoscopes.
An exoscope is an external telescope equipped with a highly advanced camera system,
providing advanced magnification and digital image processing capabilities.[5] Exoscopes address critical challenges posed by OMs while offering additional benefits
such as ease of use, improved ergonomics, magnified images of the surgical field,
and augmented depth perception. Initially characterized by two-dimensional imaging,
recent advancements have integrated three-dimensional (3D) visualization into exoscopes,
offering surgeons a stereoscopic view of the surgical field.[6] Through the sophisticated combination of a high-resolution camera, light source,
video display unit, and flexible arm, exoscopes offer neurosurgeons an optimal view
of the surgical field, particularly crucial in intricate procedures involving small
structures.[7]
[8]
The emergence of exoscopes signifies a progression in microsurgical techniques, providing
surgeons with a potent instrument capable of enhancing both surgical outcomes and
patient safety. The versatility of exoscopes is evident in their application across
various neurosurgical procedures, including skull base, transsphenoidal, cerebrovascular,
and spinal surgeries, as well as otorhinolaryngological procedures.[9]
[10]
[11]
[12]
[13]
[14]
[15] Results obtained from these procedures have shown promising outcomes when compared
with conventional visualization tools like OMs.
To date, no bibliometric study has focused on exoscopes in neurosurgery. This study
aims to fill that gap by providing the first comprehensive bibliometric analysis of
the topic. This bibliometric analysis aims to provide comprehensive insights into
the current trends in publications related to exoscopes, considering both the quality
and quantity of publications. Our goal is to explore the contributions of countries,
institutions, journals, and authors to exoscope-related research and assist researchers
in identifying current areas of interest, making predictions about the future trajectory
of exoscope-related research.
Materials and Methods
Data Collection
Scopus, developed by Elsevier Co., is an abstract and indexing database with full-text
links, offering comprehensive research capabilities. It is widely regarded as one
of the largest and most comprehensive curated databases especially for bibliometric
analysis, encompassing global research across various disciplines including medicine.
Given its extensive coverage, we opted to retrieve data for this study through a computerized
literature search using the Scopus database.[16]
Retrieval Strategies
The search for research articles related to exoscopes in neurosurgery was conducted
on December 31, 2023. The following search terms were employed: “exoscope OR exoscopic
AND neurosurgery OR brain OR spine OR cadaver OR laboratory.” Only articles published
in English between January 1, 2002, and December 31, 2023, were included. The database
search initially retrieved 236 publications, and after excluding editorials, reprints,
book chapters, conference abstracts, proceedings papers, brief reports, retracted
publications, corrections, news items, and non-English literary works, 186 publications
were included in the final analysis. [Fig. 1] illustrates the flowchart of our retrieval strategy.
Fig. 1 Retrieval flowchart.
Data Extraction and Descriptive Analysis
Records of all publications, including titles, abstracts, countries of publication,
publication years, authors, institutions, journals, keywords, citations, references,
etc., were downloaded and exported in comma-separated value files. Data from these
files were processed after importing them into Microsoft Excel (Version 16.77.1).
Following data processing, the data was descriptively analyzed.
Bibliometric and Visualization Analysis
For bibliometric and visual analysis, VOSviewer (Version 1.6.19) was utilized. VOSviewer,
developed by Professors Van Eck and Waltman, is a bibliometrics software with text
mining capabilities for extracting crucial parameters from a large number of scientific
articles. It generates maps and networks based on network, bibliographic, and text
data.[17] Our research used VOSviewer to perform visual network analysis such as countries
coauthorship analysis and keyword cooccurrence analysis.
Results
A total of 236 published articles were screened, resulting in the inclusion of 186
articles in the final analysis. Limited publications were observed until 2015, with
a gradual increase thereafter, peaking in the years 2017 to 2022 ([Fig. 2]). [Fig. 2] illustrates a consistent growth trend in research papers on exoscopes in neurosurgery
over the past 20 years. [Table 1] presents the top articles on exoscopes in neurosurgery research along with their
citation counts.[4]
[7]
[10]
[15]
[18]
[19]
[20]
[21]
[22]
[23]
[24]
[25]
[26]
[27]
[28]
[29]
[30]
[31]
[32]
[33]
Fig. 2 Yearly publication trend.
Table 1
Top cited articles
Rank
|
Article
|
Year of publication
|
Citations
|
1
|
Initial Clinical Experience with a High-Definition Exoscope System for Microneurosurgery[18]
|
2010
|
101
|
2
|
A High-Definition Exoscope System for Neurosurgery and Other Microsurgical Disciplines:
Preliminary Report[4]
|
2008
|
96
|
3
|
Vitom-3D for Exoscopic Neurosurgery: Initial Experience in Cranial and Spinal Procedures[19]
|
2017
|
86
|
4
|
VITOM 3D: Preliminary Experience in Cranial Surgery[20]
|
2017
|
72
|
5
|
The Exoscope in Neurosurgery: An Innovative “Point of View.” A Systematic Review of
The Technical, Surgical, and Educational Aspects[21]
|
2019
|
71
|
6
|
Lessons Learned Using a High-Definition 3-Dimensional Exoscope for Spinal Surgery[22]
|
2019
|
69
|
7
|
Initial Experience Using a High-Definition 3-Dimensional Exoscope System for Microneurosurgery[7]
|
2018
|
66
|
8
|
Advances In Intraoperative Optics: A Brief Review of Current Exoscope Platforms[23]
|
2020
|
59
|
9
|
The Exoscope in Neurosurgery: An Overview of The Current Literature of Intraoperative
Use in Brain and Spine Surgery[10]
|
2021
|
53
|
10
|
Infratentorial Supracerebellar Resection of a Pineal Tumor Using a High Definition
Video Exoscope (VITOM®)[24]
|
2012
|
52
|
11
|
Initial Experience with 3-Dimensional Exoscope-Assisted Transmastoid and Lateral Skull
Base Surgery[15]
|
2019
|
52
|
12
|
Use Of the Video Telescope Operating Monitor (VITOM) as an Alternative to The Operating
Microscope In Spine Surgery[25]
|
2012
|
51
|
13
|
Application of a Compact High-Definition Exoscope for Illumination and Magnification
in High-Precision Surgical Procedures[26]
|
2017
|
51
|
14
|
First-In-Man Clinical Experience Using a High-Definition 3-Dimensional Exoscope System
for Microneurosurgery[27]
|
2019
|
46
|
15
|
Preliminary Clinical Microneurosurgical Experience with the 4K3-Dimensional Microvideoscope
(ORBEYE) System for Microneurological Surgery: Observation Study[28]
|
2019
|
45
|
16
|
Pros And Cons of Using ORBEYE™ for Microneurosurgery[29]
|
2018
|
45
|
17
|
Endoneurosurgical Resection of Intraventricular and Intraparenchymal Lesions Using
the Port Technique[30]
|
2013
|
44
|
18
|
From Exoscope into The Next Generation[31]
|
2017
|
44
|
19
|
3D Exoscope System in Neurosurgery-Comparison of a Standard Operating Microscope with
a New 3D Exoscope in The Cadaver Laboratory[32]
|
2019
|
41
|
20
|
Fluorescence-Guided Surgery in High Grade Gliomas Using an Exoscope System[33]
|
2014
|
39
|
Contributions of Countries/Regions
The top 10 countries contributing significantly to publications in exoscope research
are listed in [Table 2]. The United States led with the highest number of articles (72), followed by Italy
(35), Germany (25), Japan (23), and China (11). In terms of total citations, the United
States also held the top position (1,259), with an average citation index (ACI) reaching
17.49. Italy, Germany, Finland, and Brazil followed in citation frequency. The ranking
by ACI placed Brazil at the top, followed by the United States, Germany, Malaysia,
and Ireland ([Fig. 3]).
Table 2
Top countries
Rank
|
Country
|
Documents
|
Citations
|
ACI
|
1
|
United states
|
72
|
1,259
|
17.49
|
2
|
Italy
|
35
|
394
|
11.26
|
3
|
Germany
|
25
|
361
|
14.44
|
4
|
Japan
|
23
|
217
|
9.43
|
5
|
China
|
11
|
35
|
3.18
|
6
|
Finland
|
9
|
81
|
9.00
|
7
|
Austria
|
7
|
50
|
7.14
|
8
|
Russian
|
4
|
7
|
1.75
|
9
|
Dominican Republic
|
3
|
7
|
2.33
|
10
|
India
|
3
|
11
|
3.67
|
11
|
Ireland
|
3
|
25
|
11.67
|
12
|
Switzerland
|
3
|
16
|
5.33
|
13
|
Brazil
|
2
|
52
|
26.00
|
Abbreviation: ACI, average citation index.
Fig. 3 Publications from each country.
Contributions of Research Institutions
Top-cited institutions in exoscope research were predominantly located in the United
States. Notable institutions, their publication volumes, and citations are detailed
in [Table 3]. Cedars-Sinai Medical Center (United States) had the highest citations (181), followed
by SBH Health System (United States), University of Pennsylvania (United States),
Johns Hopkins (United States), and University of Helsinki (Finland). The ACI for institutions
ranked Cedars-Sinai (60.33) at the top, followed by SBH Health System (39.00), Johns
Hopkins (29.00), and Mayo Clinic Jacksonville Florida (16.00).
Table 3
Top institutions with highest number of citations
Rank
|
Organizations
|
Citations
|
Documents
|
ACI
|
1
|
Cedars-Sinai Medical Center, United States
|
181
|
3
|
60.33
|
2
|
SBH Health System, United States
|
78
|
2
|
39.00
|
4
|
Hospital of the University of Pennsylvania, United States
|
68
|
5
|
13.60
|
3
|
Johns Hopkins University School of Medicine, United States
|
58
|
2
|
29.00
|
5
|
University of Helsinki and Helsinki University Hospital, Finland
|
39
|
4
|
9.75
|
6
|
Mayo Clinic, Jacksonville, United States
|
32
|
2
|
16.00
|
7
|
RWTH Aachen University Hospital, Germany
|
11
|
4
|
2.75
|
Abbreviation: ACI, average citation index.
Contributions of Authors'
In terms of first authors, A.J. Schupper (United States) led with four publications,
followed by several authors with three articles each. Constantinos Hadjipanayis (United
States) was the last author with the most publications (7), followed by Gabriel Zada
and K.L. Chaichana (United States) with six each. David Langer (United States) and
Martins Lehecka (Finland) were last authors in five articles each. Several authors
had three publications as the last author. The details of top first and last authors
are given in [Tables 4] and [5], respectively. An author-bibliographic coupling analysis map generated using VOSviewer
is presented in [Fig. 4].
Table 4
Top first authors with highest number of articles
Rank
|
First author
|
Articles as first author
|
H-index of the author
|
Affiliations[*]
|
1
|
Schupper, Alexander J.
|
4
|
15
|
Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, NY,
United States
|
2
|
de Divitiis, Oreste
|
3
|
43
|
Department of Neurosurgery, Università degli Studi di Napoli “Federico II,” Naples,
Italy
|
3
|
Mamelak, Adam N.
|
3
|
51
|
Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, United States
|
4
|
Rossmann, Tobias
|
3
|
4
|
Department of Neurosurgery, Helsinki University Hospital, University of Helsinki,
Helsinki, Finland, Department of Neurosurgery, Kepler University Hospital, Neuromed
Campus, Linz, Austria
|
5
|
Strickland, Ben A.
|
3
|
14
|
Department of Neurosurgery, University of Southern California, Los Angeles, CA, United
States
|
* Affiliations given here are at the time of article writing and may change afterwards.
Table 5
Top last authors with highest number of articles
Rank
|
Last author
|
Articles as last author
|
H-index of the author
|
Affiliations[*]
|
1
|
Hadjipanayis, Constantinos
|
7
|
44
|
Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, Mount Sinai Beth
Israel, New York, NY, United States
|
2
|
Zada, Gabriel
|
6
|
42
|
Department of Neurological Surgery, Keck School of Medicine, University of Southern
California, Los Angeles, United States
|
3
|
Chaichana, Kaisorn L.
|
6
|
51
|
Department of Neurosurgery, Mayo Clinic, Jacksonville, United States
|
4
|
Langer, David
|
5
|
27
|
Department of Neurosurgery, Lenox Hill Hospital, New York, NY, United States
|
5
|
Lehecka, Martin
|
5
|
27
|
Department of Neurosurgery, Helsinki University Hospital, Helsinki, Finland
|
* Affiliations given here are at the time of article writing and may change afterwards.
Fig. 4 Authorship coupling analysis (co-citation analysis) using VOSviewer. Each node represents
a different author, and the node size is proportionate to the number of citations.
Analysis of Core Journals
The top five journals publishing research on exoscopes in neurosurgery, along with
their publication counts, impact factors, and average citation indices, are summarized
in [Table 6]. World Neurosurgery had the highest number of publications (41), followed by Operative Neurosurgery (21), and Acta Neurochirurgica (13). Acta Neurochirurgica and Operative Neurosurgery had the highest impact factors (2.4 and 2.3, respectively). Operative Neurosurgery led in ACI (20.76).
Table 6
Top journals with most published articles
Rank
|
Journal
|
Number of publications count
|
Citation
|
JIF (2022)
|
JCR (2022)
|
ACI
|
1
|
World Neurosurgery
|
41
|
565
|
2.21
|
Q2
|
13.78
|
2
|
Operative Neurosurgery
|
21
|
439
|
2.3
|
Q2
|
20.76
|
3
|
Acta Neurochirurgica
|
13
|
150
|
2.4
|
Q1
|
11.54
|
4
|
Journal of Neurological Surgery, Part A: Central European Neurosurgery
|
7
|
106
|
0.98
|
Q3
|
15.14
|
5
|
Surgical Neurology International
|
5
|
16
|
0.76
|
Q3
|
3.20
|
Abbreviations: ACI, average citation index; JCR, Journal Citation Reports; JIF, Journal
Impact Factor.
Keyword Analysis of Research Hotspots
Keyword cooccurrence analysis revealed the top 20 keywords in exoscope research ([Table 7]). The overlay visualization map ([Fig. 5]) highlighted early keywords focused on the use of exoscopes in neurosurgical procedures,
while recent keywords emphasized ergonomics and diagnostic imaging. A word cloud of
top author-indexed keywords is presented in [Fig. 6].
Fig. 5 Keywords cooccurrence analysis (overlay visualization map) using VOSviewer. Each
node represents a different keyword, and the node size is proportionate to the number
of times the keywords used in the articles.
Fig. 6 Word cloud of keywords.
Table 7
Top keywords
Rank
|
Keywords
|
Occurrences
|
1
|
human
|
167
|
2
|
article
|
138
|
3
|
humans
|
134
|
4
|
exoscope
|
122
|
5
|
neurosurgery
|
121
|
6
|
clinical article
|
94
|
7
|
adult
|
91
|
8
|
male
|
90
|
9
|
neurosurgical procedures
|
88
|
10
|
microsurgery
|
87
|
11
|
female
|
83
|
12
|
procedures
|
81
|
13
|
middle aged
|
59
|
14
|
aged
|
50
|
15
|
ergonomics
|
47
|
16
|
craniotomy
|
46
|
17
|
nuclear magnetic resonance imaging
|
46
|
18
|
brain tumor
|
44
|
19
|
three-dimensional imaging
|
44
|
20
|
diagnostic imaging
|
42
|
Analysis of Fields
Out of 186 articles, 164 were original articles and 22 were reviews. Articles covered
various neurosurgical disciplines, with 87 focusing on the brain, 25 on the spine,
and 26 on both. Fourteen articles explored topics related to otology. The detailed
breakdown is provided in [Table 8].
Table 8
Articles in different fields
Fields
|
No. of articles
|
Brain only
|
87
|
Spine only
|
25
|
Brain and spine
|
26
|
Otology
|
14
|
Laboratory studies (cadaveric/anatomic specimens, animals)
|
13
|
Others (training models, devices, surveys, etc.)
|
23
|
Discussion
This study analyzes the evolution of research related to exoscopes, exploring the
body of literature, contributions from countries, institutions, authors, journals,
and prevailing research topics in exoscope utilization. Through a methodical approach,
this study offers crucial perspectives to help researchers and clinicians navigate
the growing literature and engage with the most recent developments in exoscope research.
Scopus was selected as the database for this study, as it is considered as the most
suitable bibliometric analysis database.[34] It offers researchers the ability to search both forward and backward from a particular
citation. Compared with PubMed and Google Scholar, it provides highly structured metadata,
including author affiliations, citation counts, and document types. Scopus integrates
with tools like VOSviewer, enabling users to create visual maps of research collaborations,
citation networks, and keyword cooccurrence.[35]
[36]
Although exoscope as an intraoperative tool was discussed in the 1990s,[37]
[38] its widespread use did not occur until after 2015. The rise in exoscope research
is observed from 2017 onwards, with 2022 being the most productive year yielding 46
publications. The recent surge in exoscope research reflects the growing recognition
of exoscope as a valuable surgical tool. This trend may be driven by technological
improvements, such as the introduction of 3D exoscopes, emerging applications of exoscopes
in microsurgery, and its other proposed benefits.[5]
[39]
[40]
[41]
In terms of publication output, resource-rich countries dominate the landscape. The
United States emerged as the most prolific contributor, publishing 72 articles. Italy,
Germany, Japan, and China followed, indicating a notable concentration of research
activity in these countries. The United States not only leads in publication quantity
but also in total citations, amassing a significant 1,259 citations with an ACI of
17.49. Italy and Germany follow the United States in citation ranking, with 394 and
361 total citations, respectively, highlighting the impact of research originating
from these nations. Ireland, Brazil, Germany, and Malaysia are also ranked high in
the ACI, suggesting that even with somewhat smaller publication counts, their research
related to exoscopes is frequently highly cited.[42] However, the underrepresentation of low- and middle-income countries (LMICs) in
exoscope research highlights disparities in access to advanced surgical technologies.
This emphasizes the importance of creating global research networks and ensuring equitable
health care resources.
The top-cited institutions in exoscope research predominantly hail from the United
States, with Cedars-Sinai Medical Center leading in both total citations (181) and
ACI (60.33). Collaborations were observed among the United States, Brazil, Germany,
and Switzerland.[42] Notably, although Egypt, Finland, and Austria may have fewer publications, they
engage closely in collaboration with other major contributors. [Fig. 7] presents the coauthorship analysis showing collaboration between different countries
with respect to research on exoscope. For future research, creating a worldwide research
network and ensuring equitable health care resources for LMICs would be valuable undertakings.[42]
Fig. 7 Coauthorship analysis (unit of analysis = countries) using VOSviewer. Each node represents
a different country, and the node size is proportionate to the contribution of each
country in exoscope-related research.
The analysis of author contributions to exoscope research highlights A.J. Schupper
from the United States as the leading contributor with four publications as the first
author. Notably, Constantinos Hadjipanayis from the United States emerges as the one
with the highest overall contribution as the last author, having authored seven publications.
The first authorship acknowledges the individual who plays a pivotal role in the conception
and execution of the research. The last author position suggests leadership roles
in guiding and overseeing research projects.[43] Recognizing the contributions of both first and last authors is crucial for fostering
a collaborative and equitable research environment, where seasoned researchers mentor
and support junior colleagues.
World Neurosurgery (Impact Factor [IF] = 2.21, Q2), Operative Neurosurgery (IF = 2.3, Q2), and Acta Neurochirurgica (IF = 2.4, Q1) were the key journals in publishing a considerable volume of research
and high-impact publications. The prevalence of words such as microsurgery, ergonomics,
3D imaging, brain tumors, and craniotomy in top 20 keywords suggest the exoscope applications,
its advancements, and key areas of research being pursued for exoscope.[41]
[44] Exoscope provides improved ergonomics for better operative experiences and longevity,
especially in neurosurgery where musculoskeletal disorders are prevalent.[45] The 3D exoscope enhances surgeon comfort and satisfaction, particularly in procedures
requiring nonneutral body positioning, like spine procedures[46] or supracerebellar infratentorial approach.[47] These continuous innovations are enhancing exoscope technology, leading to its increasingly
widespread adoption.
The 186 articles included in this study reflect a diverse spectrum of topics within
neurosurgery and otology. A significant number, 87 articles, focused on the brain,
highlighting the predominance of research in this domain of neurosurgery. The spine
is another important focus of interest, with 25 articles related to spinal neurosurgery.
In addition, 26 articles covered both brain and spine, indicating the interrelation
of these areas in neurosurgical research. Notably, otology, a discipline within ear
and skull base surgery, was represented by 14 articles. The diverse applications of
exoscope across neurosurgery, spinal surgery, and otology demonstrate its versatility
and potential to revolutionize multiple fields.
This study finds its strength in being the first bibliometric review done for exoscopes.
This study used not only performance analysis tools but also visualization tools to
represent the literature on exoscope-related research. However, this study also had
several limitations. The database used for this research was Scopus, which may have
led to the omission of articles not published in Scopus. Despite its advantages, Scopus
has certain inherent limitations that may affect the scope of this study. Compared
with other databases such as Web of Science, Scopus offers relatively recent coverage,
with indexing beginning primarily in 1970 for most disciplines and limited retrospective
inclusion of older publications. As a result, we might have inadvertently missed some
earlier articles. Similarly, Scopus covers a broad range of document types including
articles, reviews, and conference papers, it excludes some formats like books, book
chapters, and theses, which are often included in Google Scholar or PubMed. Language
and time filters were used, which might have excluded some relevant articles. The
quality of studies was not considered in this review.[42]
Conclusion
Exoscope has been found to be a valuable tool in neurosurgical armamentarium with
the surge in research related to exoscope starting in 2017. The United States is the
most important contributor, followed by Italy and Germany. World Neurosurgery is the journal that has published the most articles related to exoscope. Recent keywords
such as 3D technology and ergonomics suggest the recent advancements and hotspots
in exoscopic research. Exoscopes have been used in diverse surgical procedures from
brain and spine to otorhinolaryngological procedures indicating its versatile utilization.
Future advancements and research will be vital as exoscope can be a new gold standard
in microneurosurgery.