An international bibliometric study of scientific articles on intracranial aneurysms

Abstract

Objectives

The number of original scientific researches on intracranial aneurysms has risen over the last 30 years. Despite the rise in the number of articles, there is no up-to-date exhaustive bibliometric research in the literature. This study aimed to contribute to the literature via a bibliometric analysis of the original scientific researches on intracranial aneurysms published over the last 30 years.

Methods

The literature review was done using the Web of Science. All articles and its citations containing aneurysm keywords were analyzed in the "title" section of articles published in the research areas: Neurosciences Neurology during 1980–2019. Correlation analyses between the number of articles produced by the countries and their economic and development indicators of gross domestic product, and Human Development Index were analyzed using the Spearman correlation coefficient. Linear regression analysis was utilized to estimate the number of articles to be published in the future.

Results

There were a total of 21,673 publications on intracranial aneurysms. Of these publications, 13,371 (61.7%) were articles. The three countries that produced the most articles were the USA (4098), Japan (2668), and China (937). A statistically significant correlation was found between the development indicators of world countries and publication productivity (p<0.001). The three journals that produced the most publications were Neurosurgery, Journal of Neurosurgery, and American Journal of Neuroradiology. The most cited article was published in Journal of Neurosurgery.

Conclusion

This bibliometric study provides a collection of data that will help design future research on intracranial aneurysms more efficiently and make innovations at greater speed.

Introduction

Intracranial aneurysms are the number one cause of non-traumatic subarachnoid hemorrhage. ¹ High mortality and morbidity rates of ruptured intracranial aneurysms are still a serious health problem. ² The survival rate after aneurysmal subarachnoid hemorrhage (SAH) has increased by 17% in the past few decades, probably owing to better diagnosis, early aneurysms repair, prescription of nimodipine, and advanced intensive care support. ³ Although the mortality rate related to acute SAH has decreased from 50% to 35% in recent years, there is still critical morbidity and mortality, which can be related to the fact that 25% of patients are deceased before reaching the hospital, the lack of specialists or equipment in the first hospital reached, and the continuing debates on the optimal management of aneurysmal SAH.

The technological innovations contributed to the developments in the diagnosis and treatment of aneurysms. Some important developments in the diagnosis of intracranial aneurysms are the availability of Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) throughout the world, increasing quality of imaging techniques, high specificity and sensitivity of Computed Tomography Angiography (CTA) and Magnetic Resonance Angiography (MRA) as non-invasive methods, and Digital Subtraction Angiography (DSA) replacing conventional angiography. While surgical clipping had previously been the gold standard choice of treatment for intracranial aneurysms, endovascular treatment has become an alternative to surgery following the invention of the Guglielmi controlled-release coil system in 1990. ⁴ In 1997, the International Subarachnoid Aneurysms Trial (ISAT), a multi-centered prospective randomized clinical trial comparing the results of surgical clipping and endovascular coiling in ruptured intracranial aneurysms, came out in favor of endovascular treatment, and has since become the choice of treatment.^5,6

The economies of developed countries are well known to be closely associated with the medical service received by their citizens as well as the development of innovations and availability of technology. While some hospitals in undeveloped countries do not even possess a CT machine, MRA with high resolution is a common diagnostic method in the USA. Therefore, undeveloped countries can hardly compete with developed countries regarding research output. The indicators of gross domestic product (GDP), purchasing power parity (PPP), and human development index (HDI) are the most valuable and common indexes used for comparison of the development levels and economic powers of countries.

The current study is confined only to major research articles and excluded abstracts from meetings, books, case reports, letters to the editor, and reviews. The research community and clinical professionals would be interested in the research output on intracranial aneurysms over the years from institutions and scientists across the world. This information can be useful for planning research studies in a more efficient way and developing innovations faster. Moreover, it can be used to scrutinize the reasons why particular types of research have been carried out by the leading institutions over the years.

Bibliometric analysis is a method that is utilized for analyzing scientific outputs such as articles and books using statistical methods.^7,8 Researchers can check the current state of research by particular institutions and authors via such bibliometric analysis. Furthermore, they can make comparisons between general journals publishing the results of large trials and specialty journals, which are leaders in publishing innovations. The network visualization figures make it easier for readers to understand articles, citations, co-citations, and other bibliometric analysis findings by visualizing them. In addition, detailed explanations of the figures are presented in the figure legends.

In line with the notable increase in the number of publications in recent years, there is a parallel increase in bibliometric studies in the field of health. Recently, there have been bibliometric studies in various medical fields. Kiraz and Demir (2020) analyzed 13,662 articles about spinal cord injury between 1980 and 2018 through bibliometric analyses. ⁹ Demir and Comba (2020) reported the abstracts of 6545 articles on celiac published between 1980 and 2018.¹⁰ Ozsoy and Demir (2019) analyzed 9087 publications about bariatric surgery published between 1980 and 2016.¹¹ An analysis and summary of thousands, maybe tens of thousands, of publications with bibliometric studies provide a convenient resource for researchers conducting research in this field. Through the analysis of the publications in a specific research field, bibliometric analyses are able to identify the top active authors, institutions, countries, and journals as well as the international collaborations between them. The keyword analyses reveal the trend topics or the most investigated topics. Citation analyses reveal the most effective publications and journals. ¹²

To our best knowledge, there is no up-to-date exhaustive bibliometric research on intracranial aneurysms in the literature. This study provides a summary of the articles on aneurysms published between 1980 and 2019 through bibliometric analyses. It aims to reveal the most effective countries, institutions, and authors, the most cited publications and journals, and international collaborations. Keyword analyses identified the trend topics and aimed to discuss the trend research areas about this issue. In addition, correlation and regression analyses aimed to identify the course of publication productivity and the effective factors in publication productivity.

Material and methods

Search strategy

The literature review was performed using Web of Science (WoS: by Clavariate Analytics) database (access date: 7 April 2020). All the articles and its citations that included aneurysm keywords in the “title” section of the articles published in the WoS database between 1980 and 2019 were analyzed bibliometrically. The codes given in parentheses (Title: (“aneurysm*”) Refined by: Research Areas: (Neurosciences Neurology) and Document Types: (Article) Timespan=1980-2019. Indexes=SCI-Expanded, SSCI, A&HCI, CPCI-S, CPCI-SSH, BKCI-S, BKCI-SSH, ESCI) were used as keywords for the search.

Statistical methods

The normality of the data distribution was tested using the Shapiro–Wilk test. Correlation analyses between the number of articles produced by the countries and their economic and development indicators of GDP (gross domestic product), GDP PPP (purchasing power parity) (data was obtained from the World Bank Group website), ¹³ and HDI (Human Development Index) (data was obtained from the United Nations Development Programme Human Development Report 2019) ¹⁴ were analyzed using the Spearman correlation coefficient in line with the data distribution. Linear regression analysis was utilized to estimate the number of articles to be published in the future. p<0.05 was taken as statistically significant. Statistical analyses were performed using SPSS (Version 22.0, SPSS Inc., Chicago, IL, ABD, License: Hitit University) package programming. Bibliometric analysis, citation/co-citation analysis, and network visualizations were done using VOS viewer (Version 1.6.15) package program. ¹⁵

Results

The literature review revealed a total number of 21,673 publications. Of all these publications, 13,371 (61.7%) were articles, 2140 (9.9%) were Meeting Abstracts, 1208 (5.6%) were Letters, 965 (4.5%) were Reviews, 716 (3.3%) were Proceedings Papers, and the rest were in the “other publications” category (Editorial Material (3062), Note (388), Correction (93), Book Chapter (55), Early Access (30), News İtem (29), Reprint (32), Book (1), Discussion (3), Retracted Publication (1), Retraction (1), Bibliography (1)). This study performed the bibliometric analysis of only 13,371 publications that were articles; the other publication types were excluded. Of all the articles, 94.4% (12,619) were written in English. The remaining 5.6% were published in other languages (Japanese (258), French (176), Spanish (106), German (76), Italian (51), Czech (31), Russian (24), Portuguese (22), Chinese (3), Polish (2), Slovak (2), Estonian (1), Hungarian (1), and Turkish (1)).

Development of publications and citations

The distribution of the articles by years is given in Figure 1, which also demonstrates the regression analysis about the estimations for the number of publications in the future. The estimated number of publications was 881 (95% CI: 787–970) for the year 2020 and 1038 (869–1203) for the year 2029.

Figure 1.

Number of publications by years on aneurysms.

Active countries

The distribution of the articles according to countries is given in Figure 2. Top active countries that produced more than 200 publications were the USA (4098), Japan (2668), China (937), Germany (910), France (734), South Korea (715), Canada (598), UK (524), Netherlands (470), Italy (460), Switzerland (303), Turkey (300), Finland (246), and India (220). Figure 3 demonstrates the network map of the international collaboration among 46 out of 119 countries that had at least 15 articles.

Figure 2.

World map for the publication productivity of worldwide countries on aneurysms. In the indicator given at the bottom left of the figure, productivity increases from green to red.

Figure 3.

Network visualization map for international collaboration of worldwide countries on aneurysms. The size of the circle shows the large number of publications, the colors indicate the cluster of collaboration, and the thickness of the lines indicates the strength of collaboration.

Correlation analysis

A statistically significant correlation was found between the number of articles produced by the countries about intracranial aneurysms and their GDP, GDP PPP, and HDI indicators (r=0.701, p<0.001; r=0.639, p<0.001, r=0.574, p=0.001).

Active journals

There were 258 journals where the 13,371 articles were published. These journals included 48 journals that produced at least 40 publications about aneurysm. Table 1 demonstrates the top 48 journals that produced the highest number of publications. In addition, the last column of the table includes the total number of citations of the journals and the average number of citations per article. The citation network visualization map between these journals is given in Figure 4.

Table 1.

Active journals on aneurysm.

Journals	RC	C	AC	Journals	RC	C	AC
Neurosurgery	1272	49,647	39.0	Neurology India	106	629	5.9
Journal of Neurosurgery	1225	64,573	52.7	Cerebrovascular Diseases	89	1879	21.1
American Journal of Neuroradiology	1013	38,175	37.7	Journal of Neuroradiology	86	1185	13.8
World Neurosurgery	833	4208	5.1	Neurology	83	4242	51.1
Acta Neurochirurgica	714	11,937	16.7	Neurosurgical Focus	81	553	6.8
Interventional Neuroradiology	608	3203	5.3	Minimally Invasive Neurosurgery	80	1057	13.2
Surgical Neurology	601	13,743	22.9	Childs Nervous System	77	1219	15.8
Stroke	541	35,730	66.0	Arquivos De Neuro Psiquiatria	73	402	5.5
Journal of Neurointerventional Surgery	501	5595	11.2	Operative Neurosurgery	71	415	5.8
Neuroradiology	410	9483	23.1	Journal of Neuroimaging	63	421	6.7
Neurologia Medico Chirurgica	398	3393	8.5	Neurocirugia	63	182	2.9
Journal of Clinical Neuroscience	357	2674	7.5	Neurosurgery Clinics of North America	58	843	14.5
Neurological Surgery	272	893	3.3	Canadian Journal of Neurological Sciences	56	834	14.9
British Journal of Neurosurgery	224	2198	9.8	Pediatric Neurosurgery	51	480	9.4
Journal of Korean Neurosurgical Society	214	1367	6.4	Journal of Neurological Surgery Part A Central European Neurosurgery	50	125	2.5
Clinical Neurology and Neurosurgery	206	2260	11.0	Journal of Neurosurgery Pediatrics	50	510	10.2
Neurological Research	178	2196	12.3	Clinical Neuroradiology	49	263	5.4
Neurochirurgie	154	853	5.5	Neurochirurgia	47	249	5.3
Neurocritical Care	148	1895	12.8	Acta Neurologica Scandinavica	45	629	14.0
Neurosurgical Review	138	1510	10.9	Journal of the Neurological Sciences	44	607	13.8
Journal of Stroke Cerebrovascular Diseases	132	696	5.3	Frontiers in Neurology	43	121	2.8
Rivista Di Neuroradiologia	129	96	0.7	Interdisciplinary Neurosurgery Advanced Techniques and Case Management	42	21	0.5
Journal of Neurology Neurosurgery and Psychiatry	119	3583	30.1	Journal of Neurosurgical Anesthesiology	42	638	15.2
Turkish Neurosurgery	112	444	4.0	Neurosurgery Quarterly	42	60	1.4

RC: record count; C: number of citations; AC: average number of citations per document.

Figure 4.

Network visualization map for citation analysis of active journals on aneurysms. The number of average citations from blue to red (blue-green-yellow-red) increases.

Active organization

Table 2 demonstrates the top 25 organizations and organizations-enhanced that produced the highest number of publications.

Table 2.

Active organization and organizations-enhanced on aneurysm.

Organizations	RC	Organizations-enhanced	RC
Mayo Clinic	333	University of California System	451
Capital Med University	216	Mayo Clinic	410
University California San Francisco	207	Harvard University	317
University Toronto	181	Utrecht University	267
Suny Buffalo	160	State University of New York Suny System	249
University Med Ctr Utrecht	160	University of Toronto	244
University Calif Los Angeles	156	Utrecht University Medical Center	232
University Helsinki	147	Capital Medical University	228
Seoul Natl University	146	Assistance Publique Hopitaux Paris APHP	225
University Pittsburgh	137	University of California San Francisco	213
Harvard University	135	Barrow Neurological Institute	203
University Iowa	133	University of Helsinki	175
Tohoku University	123	State University of New York Suny Buffalo	173
St Joseph’s Hospital	115	University of California Los Angeles	166
University Virginia	114	Helsinki University Central Hospital	164
Kyoto University	108	Pennsylvania Commonwealth System of Higher Education PCSHE	163
Thomas Jefferson University	107	University of Iowa	158
Massachusetts Gen Hospital	103	Seoul National University Snu	157
Harvard Med Sch	100	Jefferson University	147
Columbia University	97	Massachusetts General Hospital	146
University Cincinnati	96	Johns Hopkins University	141
University Florida	96	University of Pittsburgh	140
University Washington	96	University of Virginia	137
University Illinois	94	Columbia University	136
Barrow Neurological Institute	93	University of Montreal	135

RC: record count.

Active authors

The active authors who produced more than 100 articles were Rinkel GJE (199), Kallmes DF (156), Lanzino G (147), Ogilvy CS (113), Lawton MT (110), Spetzler RF (110), and Hernesniemi J (105), respectively.

Citation analysis

The 20 most cited articles according to the total number of citations are demonstrated in Table 3. The last column of the table includes the number of citations per year.

Table 3.

The 20 most cited manuscripts on aneurysm.

No	Article	Author	Journal	PY	TC	AC
1	The International Cooperative Study on the Timing of Aneurysm Surgery: Part 1: Overall management results	Kassell, NF. et al.	Journal of Neurosurgery	1990	1385	44.68
2	Guidelines for the management of aneurysmal subarachnoid hemorrhage a guideline for healthcare professionals from the American Heart Association/American Stroke Association	Connolly, E. et al.	Stroke	2012	1182	131.33
3	Long-term angiographic recurrences after selective endovascular treatment of aneurysms with detachable coils	Raymond, J. et al.	Stroke	2003	920	51.11
4	Electrothrombosis of saccular aneurysms via endovascular approach .2. Preliminary clinical-experience	Guglıelmı, G. et al.	Journal of Neurosurgery	1991	898	29.93
5	Electrothrombosis of saccular aneurysms via endovascular approach .1. Electrochemical basis, technique, and experimental results	Guglıelmı, G. et al.	Journal of Neurosurgery	1991	713	23.77
6	Guglielmi detachable coil embolization of acute intracranial aneurysm: perioperative anatomical and clinical outcome in 403 patients	Vinuela, F. et al.	Journal of Neurosurgery	1997	681	28.38
7	The international cooperative study on the timing of aneurysm surgery .2. Surgical results	Kassell, NF. et al.	Journal of Neurosurgery	1990	665	21.45
8	Prevalence of unruptured intracranial aneurysms, with emphasis on sex, age, comorbidity, country, and time period: a systematic review and meta-analysis	Vlak, Monique HM. et al.	Lancet Neurology	2011	592	59.2
9	Curative endovascular reconstruction of cerebral aneurysms with the pipeline embolization device: the Buenos Aires experience	Lylyk, P. et al.	Neurosurgery	2009	566	47.17
10	Guglielmi detachable coil embolization of cerebral aneurysms: 11 years' experience	Murayama, Y. et al.	Journal of Neurosurgery	2003	557	30.94
11	Endovascular treatment of unruptured aneurysms	Roy, D. et al.	Stroke	2001	519	25.95
12	Definition of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage as an outcome event in clinical trials and observational studies proposal of a multidisciplinary research group	Vergouwen, Mervyn DI. et al.	Stroke	2010	511	46.45
13	Magnitude and role of wall shear stress on cerebral aneurysm - computational fluid dynamic study of 20 middle cerebral artery aneurysms	Shojima, M. et al.	Stroke	2004	490	28.82
14	Changes in case fatality of aneurysmal subarachnoid hemorrhage overtime, according to age, sex, and region: a meta-analysis	Nieuwkamp, Dennis J. et al.	Lancet Neurology	2009	489	40.75
15	Risk of recurrent subarachnoid hemorrhage, death, or dependence and standardized mortality ratios after clipping or coiling of an intracranial aneurysm in the international subarachnoid aneurysm trial (isat): long-term follow-up	Molyneux, Andrew J. et al.	Lancet Neurology	2009	477	39.75
16	Endovascular treatment of posterior circulation aneurysms by electrothrombosis using electrically detachable coils	Guglıelmı, G. et al.	Journal of Neurosurgery	1992	471	16.24
17	The pipeline embolization device for the intracranial treatment of aneurysms trial	Nelson, PK. et al.	Amerıcan Journal of Neuroradıology	2011	466	46.6
18	Characterization of cerebral aneurysms for assessing risk of rupture by using patient-specific computational hemodynamics models	Cebral, JR. et al.	Amerıcan Journal of Neuroradıology	2005	455	28.44
19	Atrial septal aneurysm and patent foramen ovale as risk factors for cryptogenic stroke in patients less-than 55 years of age - a study using transesophageal echocardiography	Cabanes, L. et al.	Stroke	1993	441	15.75
20	Endovascular occlusion of intracranial aneurysms with electrically detachable coils - correlation of aneurysm neck size and treatment results	Zubıllaga, AF. et al.	Amerıcan Journal of Neuroradıology	1994	416	15.41

PY: publication year; TC: total number of citations; AC: average number of citations per year.

Co-citation analysis

The references sections of the 13,371 articles had citations to 85,908 publications. There were also 9 articles that received more than 500 citations. These top cited articles were Molyneux (2002), Wiebers (2003), Hunt (1968), Fisher (1980), Jennett (1975), Molyneux (2005), Raymond (2003), Kassell (1990), and Wiebers (1998), respectively.^5,16–23

Trend topics

There were a total of 10,741 different keywords in the 13,371 articles. A network map of the cluster analysis performed with 76 keywords used in at least 60 different articles is given in Figure 5. The network map of trend keyword analysis is shown in Figure 6. The network map of citation analysis of keywords is shown in Figure 7. These keywords are also presented in Table 4.

Figure 5.

Network visualization cluster map for keyword analysis on aneurysms. The size of the circles indicates that the keyword is used frequently. The thickness of the lines indicates the strength of relationship.

Figure 6.

Network visualization map for trends based on keyword analysis on aneurysms. The number of uses of the keyword is increasing from blue to red (blue-green-yellow-red). The size of the circles indicates that the keyword is used frequently. The thickness of the lines indicates the strength of relationship.

Figure 7.

Network visualization map for citation analysis of keywords on aneurysms. The number of citations taken by keywords increases from blue to red (blue-green-yellow-red). The size of the circles indicates that the keyword is used frequently. The thickness of the lines indicates the strength of relationship.

Table 4.

The first 76 trend keywords on aneurysm.

Keyword	O	Keyword	O	Keyword	O	Keyword	O
Subarachnoid hemorrhage	3360	Giant aneurysm	189	Unruptured aneurysm	113	Recanalization	76
Aneurysm/Aneurysms	2535	Middle cerebral artery	187	Hemodynamics	112	Computational fluid dynamics	75
Intracranial aneurysm/Aneurysms	1711	Vertebral artery	177	Magnetic resonance imaging	106	Dissection	75
Cerebral aneurysm/Aneurysms	1416	Flow diverter	176	Sah	104	Recurrence	74
Endovascular treatment	562	Coil	175	Anterior cerebral artery	101	Treatment	74
Clipping	426	Aneurysmal subarachnoid hemorrhage	171	Hemorrhage	100	Posterior communicating artery	73
Outcome	417	Complication/complications	158	Ruptured aneurysm	100	Cerebral infarction	72
Embolization	395	Basilar artery	152	Cerebral angiography	99	Internal carotid artery	72
Vasospasm	361	Cerebral vasospasm	145	Magnetic resonance angiography	99	Arteriovenous malformation	69
Vascular disorders	358	Internal carotid artery	144	Fusiform aneurysm	98	Posterior cerebral artery	69
Coiling	287	Rupture	143	Guglielmi detachable coil	96	Anterior communicating artery aneurysm	67
Coil embolization	286	Microsurgery	137	Aneurysmal bone cyst	92	Microsurgical clipping	66
Stent	284	Posterior inferior cerebellar artery	130	Unruptured intracranial aneurysm	91	Morphology	66
Endovascular	281	Risk factors	124	Endovascular coiling	89	Aneurysm clipping	62
Endovascular therapy	213	Flow diversion	123	Digital subtraction angiography	88	Cerebral blood flow	62
Dissecting aneurysm	210	Delayed cerebral ischemia	120	Surgical clipping	87	Surgical treatment	62
Surgery	210	Pipeline embolization device	117	Bypass	85	Natural history	61
Angiography	208	Anterior communicating artery	113	Aneurysm surgery	82	Rebleeding	61
Stroke	197	Hydrocephalus	113	Stent-assisted coiling	79	Prognosis	60

O: number of occurrences.

Discussion

An analysis of the number of publications by years indicated an significant increase in the articles about aneurysms over the years. Especially since the year 2008, the number of publications has increased rapidly and exceeded 400, and there have been more than 800 articles published in recent years. Regression analysis results indicated that the number of articles on this issue will continue to increase more and more.

There was a significant correlation between the number of articles on intracranial aneurysms and the development indicators of the countries, and the top 10 productive countries were those with economic power such as the USA, Japan, Germany, China, France, South Korea, Canada, UK, the Netherlands, and Italy, which indicates that publication productivity of the countries are affected by the development level. Only three developing countries were among the top 20 productive countries: Turkey, India, and Brazil. This study highlights that there is a linear relationship between the countries’ publication productivity about aneurysms and their economic power. Although this finding is not surprising, the present study demonstrates the rank among developed countries. When this rank is compared and evaluated with other bibliometric analyses of scientific topics, important information could be given about developed countries' roles in giving direction to scientific studies. The purpose of including a figure of international collaborations about the studies on aneurysms is to provide researchers interested in this topic with a different view and guide international studies in terms of collaboration. An analysis of the collaborations between the countries, as highlighted in several studies in the literature,^7–9 showed that geographically regional borders had an effect on collaborative studies.

The journals that contributed to the literature with more than 300 articles included Neurosurgery, Journal of Neurosurgery, American Journal of Neuroradiology, World Neurosurgery, Acta Neurochirurgica, Interventional Neuroradiology, Surgical Neurology, Stroke, Journal of Neurointerventional Surgery, Neuroradiology, Neurologia Medico Chirurgica, and Journal of Clinical Neuroscience. The journals with the highest average number of citations per article were Stroke, Journal of Neurosurgery, Neurology, Neurosurgery, American Journal of Neuroradiology, Journal of Neurology, Neurosurgery and Psychiatry, Neuroradiology, Surgical Neurology, and Cerebrovascular Diseases. Researchers interested in this topic are recommended to consider these journals first.

The highest total number of citations was found to belong to the article entitled “The International Cooperative Study on the Timing of Aneurysm Surgery: Part 1: Overall management results” by Kassell et al. (1990) in Journal of Neurosurgery. ²² The top two cited studies following this were the articles entitled “Guidelines for the management of aneurysmal subarachnoid hemorrhage a guideline for healthcare professionals from the American Heart Association/American Stroke Association” published in Stroke in 2012²⁴ and “Long-term angiographic recurrences after selective endovascular treatment of aneurysms with detachable coils” published in Stroke in 2003.²¹ When the average number of citations is taken into consideration, the top-cited article following these studies was “Prevalence of unruptured intracranial aneurysms, with emphasis on sex, age, comorbidity, country, and time period: a systematic review and meta-analysis” by Vlak et al. (2011) published in the Lancet Neurology. ²⁵ The study with the highest average number of citations following this was the study entitled “Curative endovascular reconstruction of cerebral aneurysms with the pipeline embolization device: the Buenos Aires experience” written by Lylyk et al. (2009) in Neurosurgery. ²⁶

Co-citation analysis results showed that the researchers cited the studies conducted by Molyneux (2002), Wiebers (2003), Hunt (1968), Fisher (1980), Jennett (1975), Molyneux (2005), Raymond (2003), Kassell (1990), and Wiebers (1998) the most in the references sections of their articles.^5,16–23 We believe that researchers planning studies about intracranial aneurysms should read these articles first.

Keyword analysis results showed that the words vascular disorders, flow diverter, delayed cerebral ischemia, pipeline embolization device, stent-assisted coiling, morphology, computational fluid dynamics, microsurgical clipping, and endovascular coiling were among the trend keywords, indicating the research popularity of the endovascular treatments in recent years. L’uther et al. (2020) reported that endovascular treatments are more popular than clipping surgeries in the treatment of intracranial aneurysms. ²⁷

Only one study was found to have had a bibliometric analysis of the studies on intracranial aneurysms. The study analyzed the studies published between 1991 and 2002 regarding China’s growing contribution to global intracranial aneurysms research. ²⁸ The present study is more comprehensive as it provides an analysis of the articles published in recent years. In addition, this study provides an analysis of global publications and involves keyword analyses and detailed citation and co-citation analyses. It also makes a holistic analysis of the global outputs about aneurysms and includes the analysis of a total of 13,371 articles. It is thus believed to be a guide for researchers who will conduct research on intracranial aneurysms.

The limitation of this study is that it reviewed the articles published in only the WoS database. The analyses did not involve Scopus and PubMed databases. In a study comparing PubMed, Scopus, and Web of Science, Falagas et al. (2008) did not recommend PubMed for detailed citation analysis, although it is a useful, fast, and easy-to-use database. In addition, Scopus covers a wider journal range, of help both in keyword searching and citation analysis, but it is currently limited to recent articles (published after 1995) compared with WoS. ²⁹ Chou (2012) compared the impact factors of the journals indexed in WoS and Scopus databases (for Engineering Education and Education Technology journals) and stated that educators and librarians trusted only the impact factor (IF) of WoS database to assess the quality of journals. In addition, due to the similarities of IF ranking between WoS and Scopus, they reported that Scopus was also a valuable tool for assessing the importance of a specific journal. ³⁰ Although the databases have different strengths and weaknesses, the two companies already have competing bibliographical citation databases in Scopus (Elsevier) and the WoS (Clarivate Analytics). We preferred WoS in our study. In addition, one database needs to be used in bibliometric studies that analyze a large number of articles. Otherwise, the same articles found in different databases (there could be thousands) would be included in the analysis twice, and the results would not be reliable.

Conclusion

This study provides a summary of the 13,371 articles about aneurysms, which indicates an increasing number of articles in the literature, published between 1980 and 2019 through bibliometric analysis methods. This summary reveals the contribution of the authors, institutions, journals, and countries about this topic and investigates the collaboration between the countries. Some important publications and journals are identified for researchers. Researchers could also benefit from the trend keywords analyses to determine new research topics This bibliometric study provides a collection of data that will help design future research on intracranial aneurysms more efficiently and make innovations at greater speed.