Special Topic: Traumatic Brain Injury

October 2014

Recent years, particularly in the United States, have seen a new awareness of the dangers and consequences of traumatic brain injury (TBI). Unfortunately, although not unexpectedly, this trend has been driven by grim developments. America’s long wars in Iraq and Afghanistan, and their toll of veterans dealing with lingering brain injuries caused by improvised explosive devices and other ordnance, have provided one impetus. And a supposedly lighter sphere of activity—the world of sports—has also deepened the sense of alarm and concern. The ravages of accumulated concussions in older professional football players, and the incidence of concussion and TBI-related deaths in collegiate and scholastic players, have prompted many to question the safety of football and other contact sports.

Recently, the world of motor racing has provided its own distressing and internationally high-profile instances, with the extensive brain trauma suffered by champion Formula One driver Michael Schumacher in a holiday skiing fall in late 2013, and the October 2014 accident during the Japan Grand Prix which, at this writing, has left young French driver Jules Bianchi hospitalized with severe brain injury.

Headlines aside, TBI is a perennially significant health problem in the general population, due not only to sporting incidents but to falls and other unforeseen workplace and household impacts, along with traffic accidents, assaults, and other causes. In the USA alone, according to figures compiled by the Centers for Disease Control and Prevention, TBI was a diagnosis in more than 280,000 hospitalizations and 2.2 million emergency-room visits in 2010, accounting for more than 50,000 deaths. Troublingly, between 2001 and 2009, the rate of ER visits for sports or recreation-related injuries resulting in a diagnosis of TB rose 57% in those aged 19 or younger.

For a look at research into TBI over the last decade and a half, ScienceWatch turned to the Web of Science. A search on pertinent variants of “trauma,” brain,” and “injury,” along with a component covering “sports” and “concussion,” produced a special data file consisting of more than 31,000 papers published between 2001 and June of 2014. From this collection, ScienceWatch highlighted the most prolific and high-impact research, including papers, authors, institutions, and journals.

Each of these listings can be accessed via the tabs above.

INCREASING ATTENTION

In breaking down the papers in the TBI database by year, it becomes evident that the volume of research has increased substantially in recent years, as the graph below illustrates. From just over 1,100 papers in 2001, the annual output of pertinent papers nearly quadrupled by 2013, approaching 4,000 for both of the last two years.

Among the papers in the database, a particular trend is an increase in the number of publications in which permutations of the term “concussion” appear among the keywords, as illustrated below.

As the graph shows, the annual number of papers mentioning “concussion” increased nearly five-fold between 2001 and 2013, with a notable spike after 2008.

AUTHORS

The topic of concussion, not surprisingly, figures in the work of many of the highly cited authors featured in this survey. Robert C. Cantu of Emerson Hospital in Boston, for example, whose 73 papers in the TBI database have collectively garnered more than 4,400 citations, coauthored a 2003 JAMA paper reporting the NCAA Concussion Study (290: 2549-55, 2003), which examined the effects of cumulative effects of concussion in collegiate football players. Collaborators on this report included other authors on our list: Kevin M. Guskiewicz of the University of North Carolina (UNC), Michael McCrea of the Medical College of Wisconsin, and UNC’s Stephen W. Marshall. Cantu has also coauthored reports on sports concussion with Mark R. Lovell of ImPACT Applications in Pittsburgh, and Paul McCrory of the University of Melbourne.

Grant Iverson and the University of British Columbia and Michael W. Collins of the University of Pittsburgh have also concentrated on concussion in athletes.

The most prolific of the authors in the TBI dataset is Patrick M. Kochanek of the University of Pittsburgh, who contributed to 300 reports; these have attracted nearly 3,800 citations. Kochanek’s papers, in particular, examine the biochemical markers of traumatic brain injury. Among his coauthors on more than a third of these papers is Pittsburgh colleague Robert S.B. Clark.

Another of the highly cited authors on our list is Michael Chopp of Henry Ford Hospital, Detroit. His 107 reports in this selection of TBI reports examine physiological aspects of traumatic brain injury in rat models.  Therapeutic methods under investigation include the intracerebral transplantation of bone marrow stromal cells. This measure has been shown to stimulate nerve regeneration, although further study is needed. Joining Chopp on many of these papers were his Henry Ford colleagues Asim Mahmood and Dunyue Lu.

Two authors based at the University of Cambridge—John D. Pickard and David K. Menon—appear frequently as coauthors on reports that examine cerebrovascular pressure and many other aspects of TBI. Both authors are credited with more than 100 reports in the TBI database, and both, respectively, have collected more than 3,000 total citations.

Andrew Maas of the University Hospital Antwerp, Belgium, is the author of nearly 100 reports, collectively cited more than 3,100 times. Many of these reports derive from the International Mission on Prognostic Analysis of Clinical Trials in Traumatic Brain Injury (IMPACT), examining outcomes in diagnostic and therapeutic measures for TBI. Gordon B. Murray of the University of Edinburgh appears on many of these reports; another occasional collaborator is Geoffrey T. Manley of the University of California, San Francisco.

Based at the Hebrew University of Jerusalem, Esther Shohami studies the pharmacology of TBI. In the papers identified for this survey, she contributed to 85 reports, collectively cited approximately 2,600 times.

Another of the featured authors, Alan I. Faden of the University of Maryland School of Medicine, whose 89 papers in the database have been cited 2,400 roughly times, appeared in ScienceWatch in 2013, discussing the journal Neurotherapeutics, of which he was then editor-in-chief.

INSTITUTIONS

As a major center of TBI research, the University of Pittsburgh stands out, topping both the listings of most-prolific and most-cited institutions. (The two measures are generally related, in that larger institutions, with their typically higher output of papers, have a clear advantage in accruing overall citations.) The 970 papers listing at least one University of Pittsburgh-affiliated author accounted for more than 16,000 citations. Next in both the prolific and total-cites categories is the University of Pennsylvania, with 771 papers and nearly 14,000 total citations. The University of Toronto, Harvard University, and Virginia Commonwealth University also rank highly by both measures.

Meanwhile, the measure of impact, or cites per paper, permits smaller or more modestly producing institutions to compete with large, prolific centers. By this measure, as mentioned above, Michael Chopp and colleagues from Henry Ford Hospital consistently produced high-impact work despite a comparatively low tally of 128 reports, averaging more than 37 citations per paper. Georgetown University and New York University, similarly, registered nearly 30 citations per paper.

COUNTRIES

Among countries represented in the TBI database, the United States stands apart, with more than 16,000 papers listing at least one US-based author. Canada, Australia, Germany, and England also rank highly as prolific producers and, subsequently, register strongly in terms of total citations.

By the measure of cites-per-paper, Scotland actually emerges (among those countries with at least 200 papers in the database) as the most consistent performer, averaging more than 20 citations each on its 449 papers. (Note: the TBI database treats England, Scotland, and the United Kingdom’s other constituent countries as separate entities, although ScienceWatch acknowledges that the matter engenders disagreement, as the recent Scottish independence referendum demonstrated. In the case of this survey, the reasons are entirely practical as opposed to political.) The Netherlands and Switzerland also recorded 20 or more citations per paper.

RESEARCH FRONTS

According to the current update to Essential Science Indicators (a subset of the Web of Science), reflecting papers published and cited over the last decade, interest in TBI has been captured in 11 Thomson Reuters Research Fronts. These discrete areas of research, as was explained in a 2013 report, are identified via automated citation analysis, when a “core” of older papers is frequently cited together by later papers, forming a cluster of closely related investigation.

The two most prominent Research Fronts correspond to the threads mentioned above: one front, with a comparatively small foundational core of four papers but more than 1,200 collective citations to the core, deals with combat-related traumatic brain injury to military personnel. The other front, with 10 core papers and nearly 900 overall citations, focuses on chronic traumatic encephalopathy and other consequences of repeated head injury in athletes, with explicit mention of retired professional football players.

The ongoing plight of athletes and veterans, and the burden of TBI in the general population, seem certain to perpetuate a high level of attention from the biomedical community.

Highly Cited Authors in Traumatic Brain Injury, 2001-2014

(Listed in alphabetical order, based on papers published in special TBI database)

Name Affiliation
Erin D. Bigler Brigham Young University, Provo, UT USA
Robert C. Cantu Emerson Hospital, Boston, MA USA
Michael Chopp Henry Ford Hospital, Detroit, MI USA
Robert S.B. Clark University of Pittsburgh, PA USA
Michael W. Collins University of Pittsburgh, PA USA
Alan I. Faden University of Maryland, Baltimore, MD USA
Kevin M. Guskiewicz University of North Carolina, Chapel Hill, NC USA
David A. Hovda University of California, Los Angeles USA
Grant L. Iverson University of British Columbia, Vancouver, Canada
Patrick M. Kochanek University of Pittsburgh, PA USA
Harvey S. Levin Baylor College of Medicine, Houston, TX USA
Mark R. Lovell ImPACT Applications, Pittsburgh, PA USA
Dunyue Lu McLaren Behavioral Health Services, Detroit, MI USA
Andrew I.R. Maas University Hospital Antwerp, Belgium
Asim Mahmood Henry Ford Hospital, Detroit, MI USA
Geoffrey T. Manley University of California, San Francisco, CA USA
Anthony Marmarou* Virginia Commonwealth University, Richmond, VA USA
Stephen W. Marshall University of North Carolina, Chapel Hill, NC USA
Michael McCrea Medical College of Wisconsin, Milwaukee, WI USA
Paul McCrory University of Melbourne, Australia
Tracy K. McIntosh Media Neuroconsultants, Media, PA USA
David K. Menon University of Cambridge, UK
Gordon B. Murray University of Edinburgh, UK
John D. Pickard University of Cambridge, UK
Esther Shohami Hebrew University of Jerusalem, Israel
Donald G. Stein Emory University, Atlanta, GA  USA
Ewout Steyerberg Erasmus University, Rotterdam, Netherlands
Kevin K.W. Wang University of Florida, Gainesville, FL USA
SOURCE: Thomson Reuters Web of Science

*Deceased, 2010

Traumatic Brain Injury: Prolific Institutions, 2001-2014

(Listed by number of papers in special TBI database)

Institution Number of Papers
University of Pittsburgh 970
University of Pennsylvania 771
University of Toronto 766
Harvard University 678
Virginia Commonwealth University 642
University of Washington 627
Baylor College of Medicine 555
Univ. of California, Los Angeles 498
Johns Hopkins University 445
United States Army 416
Monash University 381
University of Miami 372
Univ. of California, San Francisco 365
University of Melbourne 360
University of Cambridge 355
SOURCE: Thomson Reuters Web of Science

Traumatic Brain Injury: Highly Cited Institutions, 2001-2014

(Listed by number of total citations to papers in special TBI database)

Institution Citations
University of Pittsburgh 16,434
University of Pennsylvania 13,924
University of Toronto 13,629
Harvard University 12,080
Virginia Commonwealth University 11,665
Univ. of California, Los Angeles 10,699
University of Washington 9,404
Baylor College of Medicine 9,182
Univ. of California, San Francisco 7,757
Johns Hopkins University 7,701
University of Cambridge 6,884
University of North Carolina 6,735
University of Melbourne 6,651
United States Army 6,645
University of Miami 6,524
SOURCE: Thomson Reuters Web of Science

Traumatic Brain Injury : High-Impact Institutions, 2001-2014

(Listed by average cites per paper, among institutions with 100 or more papers in special TBI database)

Institution Cites per Paper
Henry Ford Hospital (Detroit, MI) 37.53
Georgetown University 28.47
New York University 28.32
University of North Carolina, Chapel Hill 27.97
King’s College London 25.28
Medical College of Wisconsin 25.26
Hebrew University of Jerusalem 24.87
Erasmus University Rotterdam 23.65
University of Zurich 23.02
Stanford University 22.96
Free University of Berlin 22.71
University of Wisconsin, Madison 22.28
University of New South Wales 22.22
Charité University Medicine Berlin 22.19
Dartmouth College 21.97
SOURCE: Thomson Reuters Web of Science

Traumatic Brain Injury: Prolific Countries, 2001-2014

(Listed by number of papers in special TBI database)

Nation Number of Papers
USA 16,134
Canada 2,144
Australia 1,793
England 1,725
Germany 1,712
China 1,331
Italy 982
Japan 779
France 782
Sweden 748
Spain 671
Netherlands 641
Switzerland 482
Scotland 449
Israel 446
SOURCE: Thomson Reuters Web of Science

Traumatic Brain Injury: Highly Cited Countries, 2001-2014

(Listed by number of total citations to papers in special TBI database)

Nation Citations
USA 252,310
Canada 33,492
England 30,110
Germany 28,343
Australia 25,154
Italy 15,658
Netherlands 12,827
Sweden 11,544
Switzerland 9,640
China 9,563
France 9,406
Scotland 9,204
Japan 9,031
Israel 8,597
Spain 5,694
SOURCE: Thomson Reuters Web of Science

Traumatic Brain Injury: High-Impact Countries, 2001-2014

(Listed by average citations per paper, of those nations that published 200 or more papers in special TBI database)

Nation Cites per Paper
Scotland 20.50
Netherlands 20.01
Switzerland 20.00
Israel 19.28
Denmark 18.41
Ireland 17.59
England 17.46
Germany 16.56
Italy 15.95
USA 15.64
Canada 15.62
Sweden 15.43
Belgium 14.36
Australia 14.03
Finland 14.02
SOURCE: Thomson Reuters Web of Science

Traumatic Brain Injury: Prolific Journals, 2001-2014

(Listed by number of papers in special TBI database)

Journal Papers
Journal of Neurotrauma 2,943
Brain Injury 1,873
Journal of Head Trauma Rehabilitation 803
Journal of Trauma 605
Critical Care Medicine 555
Archives of Clinical Neuropsychology 462
Journal of Neurosurgery 444
Neurosurgery 432
Archives of Physical Medicine and Rehabilitation 428
Clinical Neuropsychology 373
Brain Research 306
Neurorehabilitation 251
PLOS One 250
Neurology 247
Neurocritical Care 239
SOURCE: Thomson Reuters Web of Science

Traumatic Brain Injury: Highly Cited Journals, 2001-2014

(Listed by number of total citations to papers in special TBI database)

Institution Citations
Journal of Neurotrauma 28,178
Brain Injury 14,477
Journal of Trauma 12,142
Journal of Head Trauma Rehabilitation 10,544
Archives of Physical Medicine and Rehabilitation 8,796
Journal of Neurosurgery 7,775
Neurosurgery 7,503
Critical Care Medicine 7,139
Experimental Neurology 7,051
Journal of Neuroscience 6,564
Journal of Cerebral Blood Flow and Metabolism 6,258
Brain Research 5,184
Journal of the International Neuropsychological Society 4,752
Journal of Neuroscience Research 4,412
Journal of Neurochemistry 4,232
SOURCE: Thomson Reuters Web of Science

Traumatic Brain Injury: High-Impact Journals, 2001-2014

(Listed by average cites per paper, of those that published 100 or more papers in special TBI database)

Journal Cites per Paper
Journal of Neuroscience 54.70
Journal of Neuroscience Research 32.34
Experimental Neurology 30.52
Journal of Cerebral Blood Flow and Metabolism 28.32
Clinical Journal of Sport Medicine 27.92
Journal of Neurology, Neurosurgery
and Psychiatry
27.86
Journal of Neurochemistry 24.18
Pediatrics 23.54
Neuroscience 21.49
Journal of the International Neuropsychological Society 21.41
Archives of Physical Medicine and Rehabilitation 20.55
Journal of Trauma 20.07
Journal of Neurosurgery 17.51
British Journal of Sports Medicine 17.50
American Journal of Physical Medicine & Rehabilitation 17.42
SOURCE: Thomson Reuters Web of Science

Highly Cited Papers on Traumatic Brain Injury, 2001 to 2014

(Drawn from the special TBI database, listed by citations within
each multiyear grouping)

2001-2005

Paper Citations
D. Davalos, et al., “ATP mediates rapid microglial response to local brain injury in vivo,” Nature Neuroscience, 8(6): 752-8, 2005. [New York U., NY] 685
M. Asahi, et al., “Effects of matrix metalloproteinase-9 gene knock-out on the proteolysis of blood-brain barrier and white matter components after cerebral ischemia,” J. Neuroscience, 21(19): 7724-32, 2001. [Harvard U., Cambridge, MA; Tufts U., Boston, MA; Massachusetts Gen. Hosp., Charlestown, MA] 445
K.M. Guskiewicz, et al., “Cumulative effects associated with recurrent concussion in collegiate football players – The NCAA Concussion Study,” JAMA, 290(19): 2549-55, 2003. [8 US institutions] 379
R.K. Narayan, M.E. Michel, et al. (Clinical Trials in Head Injury Study Group), “Clinical trials in head injury,” J. Neurotrauma, 19(5): 503-57, 2002. [33 institutions worldwide] 376
D. Panikashvili, et al., “An endogenous cannabinoid (2-AG) is neuroprotective after brain injury,” Nature, 413(6855): 527-31, 2001. [Hebrew U. Jerusalem, Israel] 362

2006-2010

Paper Citations
C.W. Hoge, et al., “Mild traumatic brain injury in US soldiers returning from Iraq,” New Engl. J. Med., 358(5): 453-63, 2008. [US Army, Walter Reed Army Inst. Res, Silver Spring, MD; Deployment Health Clin. Ctr., Washington, DC; Uniformed Serv. U. Hlth. Sci., Washington, DC]   657
J.A. Langlois, et al., “The epidemiology and impact of traumatic brain injury – A brief overview,” J. Head Trauma Rehabilitation, 21(5): 375-8, 2006.  [Ctrs. Disease Control & Prevent., Atlanta, GA; Lockheed Martin Corp., Atlanta] 457
R.G. Ellis-Behnke, et al., “Nano neuro knitting: Peptide nanofiber scaffold for brain repair and axon regeneration with functional return of vision,” PNAS, 103(13): 5054-9, 2006. [MIT, Cambridge, MA; State Key Lab. Brain & Cognit. Sci., Hong Kong, China; U. Hong Kong, China; Fourth Mil. Med. U., Xian, China] 328
M.F. Kraus, et al., “White matter integrity and cognition in chronic traumatic brain injury: a diffusion tensor imaging study,” Brain, 130: 2508-19, 2007. [U. Illinois, Chicago; Wayne State U., Detroit, MI] 269
D. Warden, “Military TBI during the Iraq and Afghanistan wars,” J. Head Trauma Rehabilitation, 21(5): 398-402, 2006. [Walter Reed Army Med. Ctr. Dev. & Vet. Brain Injury Ctr., Washington, DC] 258

2011-2014

Paper Citations
D.J. Cooper, et al., “Decompressive craniectomy in diffuse traumatic brain injury,” New Engl. J. Med., 364(16): 1493-1502, 2011.  [10 Australia and Saudi Arabia institutions] 163
C.D. Mac Donald, et al., “Detection of blast-related traumatic brain injury in U.S. military personnel,” New Engl. J. Med., 364(22): 2091-2100, 2011. [Washington U., St. Louis, MO; Landstuhl Reg. Med. Ctr., Germany; Walter Reed Army Med. Ctr., Washington, DC] 98
B.E. Gavett, R.A. Stern, A.C. McKee, “Chronic traumatic encephalopathy: a potential late effect of sport-related concussive and subconcussive head trauma,” Clin. Sports Med., 30(1): 179, 2011.  [Bedford Vet. Affairs Med. Ctr., MA; Boston U., MA] 71
K.M. Kinnunen, et al., “White matter damage and cognitive impairment after traumatic brain injury,” Brain, 134: 449-63, 2011. [6 UK institutions] 61
G. Barkhoudarian, D.A. Hovda, C.C. Giza, “The molecular pathophysiology of concussive brain injury,” Clin. Sports Med., 30(1): 33, 2011.  [U. Calif., Los Angeles] 50
SOURCE: Thomson Reuters Web of Science

Traumatic Brain Injury: Most-Represented Fields, 2001 to 2014

(Listed by number of papers in special TBI database, as indexed in respective Web of Science journal categories

Journal Category Papers
Neurosciences 11,297
Clinical Neurology 10,977
Critical Care Medicine 5,613
Rehabilitation 4,871
Surgery 4,116
Psychology 1,921
Sport Sciences 1,642
Clinical Psychology 1,522
Psychiatry 1,437
Pediatrics 1,117
Biochemistry & Molecular Biology 950
Pharmacology & Pharmacy 864
Emergency Medicine 824
Endocrinology & Metabolism 618
Cell Biology 616
SOURCE: Thomson Reuters Web of Science

The data and citation records included in this report are from Thomson Reuters Web of ScienceTM. Web of ScienceTM is a registered trademark of Thomson Reuters. All rights reserved.