INTRODUCTION

Meningiomas are the most common (36.6%) primary intracranial tumors (1). The incidence of meningioma depends on age; while it occurs in 0.14 per 100,000 children aged 0-19, it is 37.75 per 100,000 in the 75-84 age group (1-2). They originate from arachnoidal cap cells and often adhere to the dura (3). They are mostly benign tumors, but there are also variants with malign features (4). The diagnosis of meningiomas has increased significantly with cross-sectional imaging techniques such as magnetic resonance imaging and multi-detector computed tomography (5).

In parallel with the overall increase in the number of publications recently, the number and variety of bibliometric studies have also increased (6). With many bibliometric studies conducted in this field, thousands or even tens of thousands of studies have been analyzed, thus creating a valuable source for new research. Bibliometric analysis reveals actively publishing authors, institutes, countries, journals, and their relations with each other (6). Examining the most cited publications is a frequently used method in bibliometric analysis (7,8). The number of citations of an article is an important objective indicator showing the extent of credit and interest it gets in the academic world (9). For this reason, in bibliometric studies, the 50 most cited publications are filtered and analyzed (7).

A review of the literature shows that many bibliometric studies have been conducted on various subjects in the field of neurosurgery (6,10-14). We also planned to review the 50 most cited publications on meningioma using the Thomson ISI Web of Science® Database.

METHODS

In March 2022, we searched the term “meningioma” in the “title” section and in Neurology and Neuroscience categories of the Thomson Reuters Web of Science-Science Citation Index Expanded database. The 50 most cited articles published in English since 1970 were examined.

The parameters we noted were the number of citations, the country and institute where they were submitted, the publishing journal, the year of publication, and the content of the articles. Eight journals that published two or more articles were searched using the multidisciplinary database Scopus, through the free-access portal SCImago Country & Journal Rank (SJR). The documents published by these eight journals, the citations they received, and the citation/document ratios for the last two years were noted.

The period from 1970 to present was divided into decades and grouped by the year articles were published. The content of the articles was categorized as cytogenetic studies, non-surgical or radiosurgery studies, studies on classification and scoring, progression, epidemiology-etiology studies, reviews, surgical outcome studies, and radiological studies.

Statistical Analysis

The IBM SPSS Statistics Co. 25.0 (IBM Co., Armonk, NY, USA) was used for statistical analysis. Qualitative data were defined as frequency distributions and quantitative data were presented as mean, minimum, and maximum values.

RESULTS

When the 50 most cited articles were examined, it was seen that they recorded a total of 17,432 and an average of 348.6 citations. While the most cited article received 1237 citations, the least cited one was cited 196 times (Table 1). The articles were found to be under eight different research titles. The most common article field was cytogenetic studies with 11 articles (Table 2). Others were radiosurgery, classification score system, progression, epidemiology-etiology, review, surgical outcomes, and radiology.

More than half (54%) of the articles were on studies conducted in the US, followed by Germany with 14%. The studies that led to the publication of 50 articles were conducted at 36 different institutes from 12 different countries (Figure 1). The institute that carried out the highest number of studies (5) is the Mayo Clinic (Table 3).

These articles have been published in 25 different journals. 8 journals published at least 2 or more articles (Table 4). The highest number of articles (10) was published by the Journal of Neurosurgery, which is followed by the International Journal of Radiation Oncology, Biology Physics, and the Journal of Neurosurgery with 5 articles each. We identified 8 journals which published 2 or more of the 50 most cited articles on meningioma. Examining the 8 journals using the data obtained from SJR, with Scopus data, we have seen that the average number of citations per document (cites/doc.) was 4.14, the average total documents were 949.7 in 2020, and the average total number of citations for those documents was 18307.1.

DISCUSSION

We have listed 50 most-cited articles on meningiomas. We found that these articles were published on studies conducted in 12 different countries, while the US accounted for more than half (54%) of them (Figure 1). This result is in line with the findings of other bibliometric studies (6,10-14). It goes without saying that economic development lays a suitable ground for advances in science and technology (15). The US’s ability to allocate funding and resources for scientific research thanks to its economic power enabled this country to outperform in this field, which can also be observed in the findings of this study. Based on our observation, it appears that an article on meningiomas is more likely to be cited highly if it was published in a subject-specific journal (Neurosurgery or Radiation oncology) by an English-speaking institution in the US. It is also not a coincidence that the five leading countries in terms of scientific publications are the US, Germany, Canada, France, and the UK, respectively, which enjoy developed economies and scientific productivity. In this vein, this study suggests that there is a linear relationship between the number of publications on meningiomas in these countries and their economic power. This situation gives important information about the influence of developed countries in conducting scientific studies.

When the article types were examined, the cytogenetic studies outnumbered articles in other fields. The World Health Organization (WHO) published its central nervous system classification in 1979, 1993, 2000, 2007, 2016, and 2020 (16). The importance of histomorphological features and molecular changes has increased in the last two updates. In this way, the WHO reduced the interobserver variability of histological interpretation in diagnostic criteria and to provide a more accurate classification of clinical outcomes. In accordance with this, cytogenetic studies have been widely cited and received interest in studies on meningiomas (Table 2).

According to the Thomson ISI Web of Science® Database data, recently a significant increase has been observed in the number of articles on meningioma. In the early 2000s, approximately 500 articles on meningioma were published per year, while recently, this number has approached 1500 per year. Considering the publications year of the 50 most cited articles, it was seen that most articles (38%) were published between 2000-2009. Since our bibliometric study is mostly based on the number of citations, this time interval has been accepted as normal, since it takes time to publish the articles, capture sufficient interest, organize a new study, and publish this study as well. A review of other bibliometric studies also showed that the cited articles were mostly published in the same period (6,10-14).

As far as the journals in which the most cited articles were published are concerned, the Journal of Neurosurgery, International Journal of Radiation Oncology Biology Physics, Neurosurgery, American Journal of Surgical Pathology, Journal of Neuro-oncology, Cancer, Surgical Neurology, and Proceedings of the National Academy of Sciences (PNAS) are the leading ones, respectively (Table 4). Ten of the most cited articles (Table 4) and the most cited article (Table 1) were published in the Journal of Neurosurgery. This Journal is one of the most important sources for the international neurosurgery community. Having examined other journals, we noted that they included oncology as well as neurosurgery journals. This is because meningioma is a subject studied by radiation oncology and medical oncology physicians as well as by neurosurgery physicians. It is recommended that researchers interested in this subject should be cognizant of these journals. Additionally, it has been observed that the journal named PNAS has a higher number of total citations and citations per document compared to the other journals (Table 4).

CONCLUSION

In this study, we used bibliometric analysis methods to present a scientific summary of the 50 most cited articles on meningioma, which has been increasingly studied in the literature, published between 1970-2022. This summary reveals the contributions to this topic by journals, countries, authors, and institutions. Some important publications and journals have been identified for researchers. This bibliometric study provides a collection of data that will help design future research on meningiomas more efficiently, identify gaps, and develop new approaches.

ETHICS

Ethics Committee Approval: All procedures performed were in accordance with the 1964 Helsinki Declaration. This article does not contain any studies with human participants or animals performed by any of the authors.

Informed Consent: For this type of study formal consent is not required.

Authorship Contributions

Surgical and Medical Practices: Ö.Ö., Concept: Ö.Ö., O.B., Design: Ö.Ö., Data Collection or Processing: Ö.Ö., Analysis or Interpretation: Ö.Ö., Literature Search: Ö.Ö., Writing: Ö.Ö.

Conflict of Interest: No conflict of interest was declared by the authors.

Financial Disclosure: The authors declared that this study received no financial support.