Bibliometric overview of the Top 100 most cited articles on hydrocephalus.

Background: Hydrocephalus is one of the most common brain disorders and numerous articles were published to address the clinical aspect and its management. This study aims to highlight the most influential work on hydrocephalus on bibliometric basis.
Methods: A thorough search of Scopus database was performed using the word "hydrocephalus." The 100 most cited articles were retrieved, and variables of importance were collected including the article's title, 1st author affiliation, country of origin, year and journal of publication, article's category, and citation count according to Scopus and Google scholar databases.
Results: The 100 most cited articles were thoroughly analyzed. Publication dates ranged from 1946 to 2014, with most articles (45) published between 1998 and 2007. The mean number of citations per publication was 201 with total of 20,177 citations. The United States of America contributed half of the articles. The leading institution was the Canadian hospital for Sick Children University of Toronto having published 5 articles. Hydrocephalus in general and normal pressure hydrocephalus was the two major categories addressed with most studies fall under the topic of surgical management. Neurosurgery was the specialty with the greatest contribution (47%). The articles were published in 46 different journals led by the Journal of Neurosurgery with total of 17 articles.
Conclusion: This bibliometric analysis delineates the landmark publications in hydrocephalus. The listed articles depict the myriad of studied aspects historically which helps in understanding hydrocephalus overall in evidence-based module for neurosurgeons and non-neurosurgeons. Copyright:

INTRODUCTION

Hydrocephalus is a complex condition that was first described by Hippocrates (466–377 BC), who described the associated symptoms of headache, vomiting, visual disturbance, and diplopia.[4] Throughout the years, the understanding of hydrocephalus has evolved, so it is identified as abnormal CSF physiology that results in pathological expansion of cerebral ventricles.[12] Although, many theories have been formulated to explain the molecular mechanism for development of hydrocephalus, the precise pathophysiology still unclear.[13,14] Hydrocephalus is one of the most common brain disorders that are estimated to possess mean prevalence of 85/100,000.[11] Substantial burden for both individual and society has been caused by the chronic state of hydrocephalus.[7] It is a debilitating condition which can present at any age and encompasses heterogeneous pathogenesis.[13] Hydrocephalus causes are numerous, including but not limited to, tumors, congenital or non-congenital aqueductal stenosis, or genetic syndromes. It may also complicate a wide range of conditions such as infections, head injury, malformations, and subarachnoid hemorrhage.[1,11] Although there is no cure for hydrocephalus, early diagnosis and surgical intervention can improve morbidity, mortality, and quality of life.[6]

During the past decades, as a result of advancements in radiological imaging and basic neuroscientific study tool our understanding of hydrocephalus and our ability to manage and control it effectively.[16] These advancements are reflected in scientific articles, particularly in those most influential papers that covers different aspects including natural history, pathophysiology, epidemiology, etiology, diagnostic, and treatment strategies. An understanding of the available literature and the most heavily cited works can be used for scientific and clinical purposes.

Bibliometric analysis is defined as a statistical evaluation that aims to quantify the impact of scientific articles. The term “Bibliometrics” was first employed by Alan Pritchard in 1969.[10] A citation analysis is the most common bibliometric method which serves to review and evaluate the most-cited articles in a specific research area. It aims to identify landmark publications and recognize the level of contribution made by authors, specialties, institutions, countries, and journals.[9] There is certainly a considerable number of articles that are insufficiently valued by their citation counts (CCs) despite their importance. Nonetheless, the CC remains the accepted method internationally to assess an article’s impact.

At present, citation analysis has been applied to identify articles in multiple medical and surgical fields.[15,18-20] Many analyses addressed neurosurgical topics such as meningioma,[3] acoustic neuroma,[2] low grade glioma,[5] idiopathic intracranial hypertension,[17] and yet none have been performed solely on hydrocephalus. We aimed to conduct a bibliometric analysis of the 100 most-cited works on hydrocephalus to analyze the current scientific production and to guide the health-care providers in this area.

MATERIALS AND METHODS

Search strategy

In March 2020, a title specific search was accomplished using Scopus database to identify the top 100 most cited articles on hydrocephalus. The search keyword that was used was hydrocephalus; another search keyword like “dilated ventricles, high intracranial pressure” was eliminated due to the non-specificity of the result to hydrocephalus. The search resultant was sorted in descending order according to CC. Google scholar CC was obtained by performing article title search and logging the CC of the article according to Google scholar database.

Data

Data of importance were collected and a comparative analysis between the published articles at basic six levels were made; article title, authors block, affiliation of the 1st author, country of origin, journal of publication, year of publication, CC according to Scopus database, and CC according to Google scholar database. The top 100 articles were categorized after studying the top 100 articles’ abstracts to the following two categories and seven subcategories; hydrocephalus (Clinical/Epidemiological/Historical, Genetic Association, in intracranial hemorrhage, in utero Surgical Management, Pathophysiology, Radiological Assessment, RCT on shunt Valve types, Surgical Management), Normal pressure Hydrocephalus (Clinical/Epidemiological, Guidelines, Pathophysiology, Radiological Assessment, Surgical Management, and In Alzheimer disease).

Bibliometric parameters

Contemporarily, quantifying the importance of articles is achieved using bibliometric parameters which involve the CC of articles, Journal’s SCImago Journal Rank (SJR), and Journal’s Source-normalized Impact per paper (SNIP) for journals. The CC accounts for the number of accounted citations of a pertinent article since its publication. The SJR score, which signifies the journals influence by the number of citations the journal has received and the source of the received citation. The SNIP is a parameter which symbolizes how discipline specific is the journals based on the discipline of the journals in which citations was received.

RESULTS

Article analysis

The title specific search yielded a total of 12,044 articles. The top 100 articles based on the CC were collected and the following data were recorded (Title, 1st author, journal, year of publication, CC according to Scopus, and CC according to Google scholar) [Table 1]. Altogether, the top 100 articles accumulated a total of 20,177 CCs and an average CC of 201 citations. The percentage of self-citation in our bibliometric review accounted for only 6.6% according to Scopus data base. The most cited article was published in The New England Journal of Medicine by Adams et al. by the Massachusetts Medical Society in 1965 which addressed “Symptomatic Occult Hydrocephalus With Normal Cerebrospinal fluid pressure: a treatable Syndrome” for which it received 896 citations according to Scopus database and 1619 citations according to Google Scholar Database. The range of publications started from 1946 to 2014 in which 45 articles were published between 1998 and 2007 which marks the most prolific epoch in publications history of hydrocephalus [Figure 1]. The United States of America contributed to half of top 100 most cited articles on hydrocephalus [Figure 2]. The Canadian hospital for Sick Children University of Toronto published 5 articles in our review as the most contributing institute [Figure 3]. A thorough review of the top 100 articles showed that two major categories were addressed: hydrocephalus in general and normal pressure hydrocephalus. The most studied topic falls under the umbrella of surgical management of hydrocephalus “18 articles” and the pathophysiology of hydrocephalus “14 articles” came as a 2nd in terms of study interest [Table 2]. A summary of the top 5 most cited articles and the relevant information in the study are summarized [Table 3].

Table 1:

The list of the top 100 most-cited articles on hydrocephalus.

Figure 1:

Trends of highly cited works on hydrocephalus.

Figure 2:

Top 5 most contributing countries to the most-cited works on hydrocephalus.

Figure 3:

The topmost contributing institutes to the most-cited works on hydrocephalus.

Table 2:

Studied Topics in the top 100 most cited articles on hydrocephalus.

Table 3:

Summary of the 5 top 5 most cited articles on hydrocephalus.

Author and journal analysis

In our review, around 160 authors have contributed to the top 100 most cited articles on hydrocephalus. The analysis of the contributing authors based on the 1st authors specialty demonstrated that neurosurgeons showed vast interest in hydrocephalus which accounted to approximately half of the articles in our bibliometric review [Figure 4]. A sub-analysis of the top 5 most contributing authors illustrated that Drake, J.M and Mori E both published four articles each in our review with approximately equal author Hirsch Index (H index) of 65 and 64, respectively [Figure 5].

Figure 4:

The list of contributing specialties to the most-cited articles on hydrocephalus.

Figure 5:

Top authors of contribution to the list.

The enlisted top 100 most cited articles on hydrocephalus were contributed by 46 journals. Journal based quantified inspection illustrated that the top 5 most contributing journals were accountable for producing 43 articles in our review. The Journal of Neurosurgery (JNS) published 17 articles and the 2nd most ranked journal was the Neurosurgery Journal where it produced 12 articles the SNIP and SJR scores emphasized that JNS is more influential and field specific when compared to the neurosurgery journals [Figure 6].

Figure 6:

Top journals of contribution to the list.

DISCUSSION

In the light of this bibliometric based evaluation of the impactful work on hydrocephalus to guide today’s learner in the era of informational over satiety to denote important articles that need to be acknowledged.

The observation of the published work showed that the most impactful articles started from 1946 but interestingly only between 1998 and 2008 almost half of articles in our list were produced which could be related to the radiological advancement and increasing availability of brain imaging that was started in 1980 and continued to increase until 2010 according to a review by Edelman.[8] Notably, the predominance of hydrocephalus management existed in surgical intervention around 50% of our bibliometric analysis was contributed by neurosurgeons which emphasizes the role of neurosurgeons in this field. Various other specialties have contributed to our list as well such as neurology, genetics, radiology, and others indicating the diversity of medical professions dealing with the disease.

The major categories that were encountered when we reviewed the studied topics were mainly addressing hydrocephalus in general and normal pressure hydrocephalus. The majority of the articles were focused on the former (n = 67), in which the most studied subcategory was the surgical management (n = 18) followed by studies looking into the pathophysiology of hydrocephalus, our review also yielded two randomized controlled trials mainly comparing types of shunt valves. It is important to note that none of the studies that our research has yielded discussed medical therapy of hydrocephalus which supports that hydrocephalus is a surgical disease even with the recent advancement in research to medical therapy. The remainder of topics discussed genetic association (n = 10), hydrocephalus in intracranial hemorrhage and studies of radiological nature as well as other categories. Regarding normal pressure hydrocephalus, the most frequently studied topics were clinical or epidemiological review articles (n = 10) followed by surgical management studies (n = 8). A few studies were published focusing on the association with Alzheimer’s disease and others outlining guidelines for management. The predominance of articles in our list studying hydrocephalus could probably be attributed to the incidence of the disease when compared to normal pressure hydrocephalus, as well as the more recent discovery of normal pressure hydrocephalus.

Our first ranked article was published in in 1965 by R. D. Adams titled “symptomatic occult hydrocephalus with normal cerebrospinal fluid pressure a treatable syndrome” which was released in the new England journal of medicine with a total CC of 896 (1619 citations on Google scholar). A follow-up paper after the one published by R. D. Adams and S. Hakim in the same year. The term normal pressure hydrocephalus was first introduced in this paper, which included three case reports of the condition while focusing on the clinical features as well as the diagnostic approach for the described entity, with strong focus was on the symptomology and suspected pathophysiology. The paper also addressed the variations of normal pressure hydrocephalus from other diseases that might mimic the conditions especially dementia as well as interpretations of the available investigations at the time. The paper stressed on the recognition of the syndrome due to the fact that the symptoms can subside with surgical ventricular shunting as demonstrated by their three presented cases.

Earlier in the year of 1965, S. Hakim and R. D. Adams published “The special clinical problem of symptomatic hydrocephalus with normal cerebrospinal fluid pressure, observations on cerebrospinal fluid hydrodynamics.” The study reported three cases of hydrocephalus in the setting of normal cerebrospinal fluid pressure. They also described the triad of symptoms observed in these cases constituting of the famous triad of mental derangement, gait disturbance and urinary incontinence. The researchers reported recovery of the condition by lowering the cerebrospinal fluid pressure by means of ventriculoatrial shunting, while hypothesizing on the possible mechanism of symptom formation. The article was published in the Journal of the Neurological Sciences receiving a CC of 732 in Scopus database (1266 citations on Google scholar) since its publication, placing it second in our list. Both of the studies paved the way for further clinical research by first describing this treatable entity, its clinical features and management by lowering CSF pressure by surgical shunting which remains the treatment of choice to this day.

Drake, J.M. was our highest-ranking author with the most contribution to our list (total of 4 articles) and an author H index of 63. Followed by Mori, E. with the same number of publications, however, Mori, E had a higher author H index of 65. The remaining authors in our top 5 list with highest contribution were Bradley, W.G., Hashimoto, M. and Ishikawa, M. by contributing three articles each. The authors were ranked based on the number of publications as well as the number of citations in their published works. Drake, J.M. has published one of the three randomized controlled trials in our list “Randomized trial of cerebrospinal fluid shunt valve design in pediatric hydrocephalus” in 1998. The article has made its way to our top ten list by accumulating a CC of 509 (653 citations on Google scholar). The study compared the delta valve, orbis sigma valve which were new at the time and the standard differential-pressure valve. The aim was to assess the shunt failure rate between the excess flow limiting valves and the standard differential pressure valves. Total of 344 patients were randomized and received one of the three valves. The study concluded that there was no significant difference in shunt failure rates after 1 year between the three valves. The article was released in Neurosurgery, which is the second ranking journal in our list with 12 article contribution to our list (SNIP and SJR of 1.523 and 1.29 respectively).

JNS published most of the articles in our list, by releasing 17 papers. One of which titled “Acute hydrocephalus after aneurysmal subarachnoid hemorrhage” published in 1985 by Van Gijn J was ranked 7th in our list by being cited 324 times. The study reported the incidence of hydrocephalus in 200 patients with diagnosed ruptured intracranial aneurysms. Hydrocephalus was evident in 20% of the studied cases. They also discussed the clinical and radiological features as well as management with external ventricular drain. JNS had a SNIP of 2 and a SJR of 1.69. Journal of neurology, neurosurgery and psychiatry (SNIP 2.28 and SJR 3.211), and pediatric neurosurgery (SNIP 0.492 and SJR 0.341) were placed in 3rd and 4th places, respectively, by releasing five articles each, followed by brain with a total contribution of four papers.

CONCLUSION

In this bibliometric analysis, we identified the top 100 most-cited articles with the term “hydrocephalus” using Scopus database. This study delineates the landmark publications in hydrocephalus. It identifies the articles that have addressed the historical development and provided key studies which highlight the important progress made in the field. The data presented reveals several characteristic related to the top contributions, including authors, institutions, type of study, and journal. The findings indicate that papers originating from outstanding institutions in North America and UK, published in high impact journals had the highest citations. Recognizing the most influential publications will provide an important framework to an enhanced understanding of the scientific advancements made in the field and identify potential area of research. It also serves as an efficient guide to achieving evidence-based clinical practice to optimize the outcome, which will help in reducing the disease burden.

Limitations

Inherent limitations exist when performing a citation analysis on a certain clinical topic. The database specific limitation exists where only one database was used to perform this review study. The extent of self-citation among all authors was not significant in our identified studies. The significance of highlighting the most-cited works on hydrocephalus does not necessarily confer the influence of any given article but it merely reflects and justify why the scientific committee have given it a high number of citations.