Perspectives Commentary on: Neuroimaging Changes in the Brain in Contact versus Noncontact Sport Athletes Using Diffusion Tensor Imaging by Gajawelli et al. pp. 824-828.
Ronnie P. Barnes, A.T.C. Senior Vice President, Medical Services New York Football Giants
Objective Concussion Assessment in Athletics and Diffusion Tensor Imaging Ronnie P. Barnes,1 and Heather J. McCrea2
T
he article by Gajawelli et al. in this issue of WORLD NEUROSURGERY is a thought-provoking paper that explores a topic of timely importance. Traumatic brain injury in sports and the long-term effects of such injuries has become the subject of much discussion among athletes, athletic trainers, physicians, parents, and the media. The National Football League, Centers for Disease Control, Department of Defense, and scientists from around the world are allocating resources and significant research efforts to peel back the layers of this injury. There has been a remarkable evolution in the way that those involved in athletics at all levels view traumatic brain injury. Strides have been made in systematically evaluating symptoms and devising a protocol for return-to-play decisions at all levels of sports, but there is much more to the story. One of the major obstacles medical professionals encounter as they attempt to understand this issue has been the lack of objective validated methods to assess and identify concussions. There is no clear understanding of the long-term sequelae or permanent injury from varying degrees of head trauma. Selfreporting of symptoms plays a huge role in determining who is and is not suffering from concussion. This reporting may be significantly affected by a player’s desire to play, external pressures, and even differences between players as to whether they view a particular symptom as a problem. Additionally, some players, particularly those with prior concussion history, seem to be at higher risk for developing concussion than others, and the reason for this variability among players is not fully understood.
Key words - Diffusion tensor imaging - Magnetic resonance imaging - Traumatic brain injury
Abbreviations and Acronyms DTI: Diffusion tensor imaging
Significant efforts have also been made to educate athletes on the risks associated with concussion. This has had a positive effect on cooperation with medical professionals and in increasing selfreporting of symptoms; however, there is still a strong need for an objective way to evaluate both susceptibility to concussion and consequences of specific or cumulative impacts to the head. Currently, the diagnosis of concussion is clinically based, with no specific diagnostic test available to confirm the brain injury or to monitor recovery. While functional magnetic resonance imaging and proton magnetic resonance spectroscopy have been shown to demonstrate changes after a concussion, more research needs to be done to validate these imaging modalities. Several strategies are currently being tested in order to improve assessment of injury in a more objective manner. Modalities that are currently being investigated are computerized neuropsychological testing pre- and postinjury, balance assessment, eye tracking, neurocognitive testing, diffusion tensor imaging (DTI), and biomarkers. There is, however, still a lack of validation of all of these tools as a true measure of concussions. It has long been reported in the literature regarding severe brain trauma that in addition to space-occupying bleeds and edema, diffuse axonal injury, which can be detected on DTI, can often occur through shear forces. Even in the absence of findings on computed tomography, a modality that typically identifies blood and edema, patients may have a poor clinical course. The diffuse axonal injury seen on DTI often helps explain a clinical examination that is significantly worse than would be suggested by other imaging sequences, and thus DTI has been included in the evaluation of severe traumatic brain injury for some time.
From 1Medical Services, New York Football Giants; and the 2Department of Neurosurgery, New York Presbyterian/Weill Cornell Medical Center, New York, New York, USA To whom correspondence should be addressed: Ronnie P. Barnes, A.T.C. [E-mail: [email protected]] Citation: World Neurosurg. (2013) 80, 6:796-797. http://dx.doi.org/10.1016/j.wneu.2013.10.022
796
www.SCIENCEDIRECT.com
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2013.10.022
PERSPECTIVES
Only more recently have groups, including ours, questioned whether these more subtle findings might be present in milder traumas such as those encountered during contact sports. If changes are found and then correlated with other variables such as neurocognitive testing or symptoms experienced, this could allow for a more objective assessment of athletes who undergo brain trauma. It would also be useful to know whether athletes with DTI findings were more susceptible to future injury. While we find this to be a promising technique and are currently investigating its use, one of the obstacles is the large degree of variability from one subject to the next. This requires the use of large numbers of subjects, including significant numbers of control subjects, in order to minimize bias introduced by inter-subject variability rather than true injury. The study outlined in this article is a small pilot study with only 11 contact sport athletes and 13 age-matched noncontact athletes. They do not detail what sports these athletes play or the level at which they compete, nor do they discuss the history of these athletes, i.e., did the noncontact athletes play contact sports at any point or have they had any past minor traumas outside of athletics? Do the athletes have a history of concussion or other injury in prior seasons? Additionally, it is not clear whether the 8 athletes examined postseason were similarly divided into contact and noncontact athletes, though this assumption seems likely. The authors do mention that 1 of the contact sport athletes reported a concussion during the season. It would be interesting to know anecdotally whether this athlete’s DTI showed more change from preseason to postseason than the other subjects. The authors report that P values show more significance in the
postseason scans than the preseason scans, suggesting a worsening during the season; however, the preseason and postseason scans do not appear to be directly compared for each patient. Doing such could add additional information, which the authors suggest they will do in the future. Though this study has certain limitations, most notably the small sample size, it does yield interesting results and further suggests the utility of expanding this technique to larger studies with additional controls and assessment of individual athletes over time. The authors find “significant DTI changes in the corpus callosum, the external capsule, the inferior fronto-occipital fasciculus” and regions of the superior/posterior corona radiate. These differences were present both when comparing contact and noncontact athletes preseason and postseason, and the postseason comparison appears to have more significant P values. Given the small sample size, known significant variability seen from subject to subject on DTI, and the lack of comparison between patients across time, it is difficult to truly conclude that DTI worsened over the course of the season; however, this is still a potentially interesting finding that suggests further DTI studies with larger cohorts would be beneficial.
Citation: World Neurosurg. (2013) 80, 6:796-797. http://dx.doi.org/10.1016/j.wneu.2013.10.022 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2013 Elsevier Inc. All rights reserved.
ELSEVIER Advertising Orders and Inquiries Inquiries regarding advertising in WORLD NEUROSURGERY should be directed to: Bob Heiman RH Media LLC Office: +1-856-673-4000 Cell: +1-856-520-9632 Fax: +1-856-673-4001 Email: [email protected] For all ratecards, please visit: www.elsmediakits.com.
WORLD NEUROSURGERY 80 [6]: 796-797, DECEMBER 2013
www.WORLDNEUROSURGERY.org
797
Ronnie P. Barnes, A.T.C. Senior Vice President, Medical Services New York Football Giants
Objective Concussion Assessment in Athletics and Diffusion Tensor Imaging Ronnie P. Barnes,1 and Heather J. McCrea2
T
he article by Gajawelli et al. in this issue of WORLD NEUROSURGERY is a thought-provoking paper that explores a topic of timely importance. Traumatic brain injury in sports and the long-term effects of such injuries has become the subject of much discussion among athletes, athletic trainers, physicians, parents, and the media. The National Football League, Centers for Disease Control, Department of Defense, and scientists from around the world are allocating resources and significant research efforts to peel back the layers of this injury. There has been a remarkable evolution in the way that those involved in athletics at all levels view traumatic brain injury. Strides have been made in systematically evaluating symptoms and devising a protocol for return-to-play decisions at all levels of sports, but there is much more to the story. One of the major obstacles medical professionals encounter as they attempt to understand this issue has been the lack of objective validated methods to assess and identify concussions. There is no clear understanding of the long-term sequelae or permanent injury from varying degrees of head trauma. Selfreporting of symptoms plays a huge role in determining who is and is not suffering from concussion. This reporting may be significantly affected by a player’s desire to play, external pressures, and even differences between players as to whether they view a particular symptom as a problem. Additionally, some players, particularly those with prior concussion history, seem to be at higher risk for developing concussion than others, and the reason for this variability among players is not fully understood.
Key words - Diffusion tensor imaging - Magnetic resonance imaging - Traumatic brain injury
Abbreviations and Acronyms DTI: Diffusion tensor imaging
Significant efforts have also been made to educate athletes on the risks associated with concussion. This has had a positive effect on cooperation with medical professionals and in increasing selfreporting of symptoms; however, there is still a strong need for an objective way to evaluate both susceptibility to concussion and consequences of specific or cumulative impacts to the head. Currently, the diagnosis of concussion is clinically based, with no specific diagnostic test available to confirm the brain injury or to monitor recovery. While functional magnetic resonance imaging and proton magnetic resonance spectroscopy have been shown to demonstrate changes after a concussion, more research needs to be done to validate these imaging modalities. Several strategies are currently being tested in order to improve assessment of injury in a more objective manner. Modalities that are currently being investigated are computerized neuropsychological testing pre- and postinjury, balance assessment, eye tracking, neurocognitive testing, diffusion tensor imaging (DTI), and biomarkers. There is, however, still a lack of validation of all of these tools as a true measure of concussions. It has long been reported in the literature regarding severe brain trauma that in addition to space-occupying bleeds and edema, diffuse axonal injury, which can be detected on DTI, can often occur through shear forces. Even in the absence of findings on computed tomography, a modality that typically identifies blood and edema, patients may have a poor clinical course. The diffuse axonal injury seen on DTI often helps explain a clinical examination that is significantly worse than would be suggested by other imaging sequences, and thus DTI has been included in the evaluation of severe traumatic brain injury for some time.
From 1Medical Services, New York Football Giants; and the 2Department of Neurosurgery, New York Presbyterian/Weill Cornell Medical Center, New York, New York, USA To whom correspondence should be addressed: Ronnie P. Barnes, A.T.C. [E-mail: [email protected]] Citation: World Neurosurg. (2013) 80, 6:796-797. http://dx.doi.org/10.1016/j.wneu.2013.10.022
796
www.SCIENCEDIRECT.com
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2013.10.022
PERSPECTIVES
Only more recently have groups, including ours, questioned whether these more subtle findings might be present in milder traumas such as those encountered during contact sports. If changes are found and then correlated with other variables such as neurocognitive testing or symptoms experienced, this could allow for a more objective assessment of athletes who undergo brain trauma. It would also be useful to know whether athletes with DTI findings were more susceptible to future injury. While we find this to be a promising technique and are currently investigating its use, one of the obstacles is the large degree of variability from one subject to the next. This requires the use of large numbers of subjects, including significant numbers of control subjects, in order to minimize bias introduced by inter-subject variability rather than true injury. The study outlined in this article is a small pilot study with only 11 contact sport athletes and 13 age-matched noncontact athletes. They do not detail what sports these athletes play or the level at which they compete, nor do they discuss the history of these athletes, i.e., did the noncontact athletes play contact sports at any point or have they had any past minor traumas outside of athletics? Do the athletes have a history of concussion or other injury in prior seasons? Additionally, it is not clear whether the 8 athletes examined postseason were similarly divided into contact and noncontact athletes, though this assumption seems likely. The authors do mention that 1 of the contact sport athletes reported a concussion during the season. It would be interesting to know anecdotally whether this athlete’s DTI showed more change from preseason to postseason than the other subjects. The authors report that P values show more significance in the
postseason scans than the preseason scans, suggesting a worsening during the season; however, the preseason and postseason scans do not appear to be directly compared for each patient. Doing such could add additional information, which the authors suggest they will do in the future. Though this study has certain limitations, most notably the small sample size, it does yield interesting results and further suggests the utility of expanding this technique to larger studies with additional controls and assessment of individual athletes over time. The authors find “significant DTI changes in the corpus callosum, the external capsule, the inferior fronto-occipital fasciculus” and regions of the superior/posterior corona radiate. These differences were present both when comparing contact and noncontact athletes preseason and postseason, and the postseason comparison appears to have more significant P values. Given the small sample size, known significant variability seen from subject to subject on DTI, and the lack of comparison between patients across time, it is difficult to truly conclude that DTI worsened over the course of the season; however, this is still a potentially interesting finding that suggests further DTI studies with larger cohorts would be beneficial.
Citation: World Neurosurg. (2013) 80, 6:796-797. http://dx.doi.org/10.1016/j.wneu.2013.10.022 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2013 Elsevier Inc. All rights reserved.
ELSEVIER Advertising Orders and Inquiries Inquiries regarding advertising in WORLD NEUROSURGERY should be directed to: Bob Heiman RH Media LLC Office: +1-856-673-4000 Cell: +1-856-520-9632 Fax: +1-856-673-4001 Email: [email protected] For all ratecards, please visit: www.elsmediakits.com.
WORLD NEUROSURGERY 80 [6]: 796-797, DECEMBER 2013
www.WORLDNEUROSURGERY.org
797
