Functional neuroimaging of acute oculomotor deficits in concussed athletes

Johnson, Brian D.; Zhang, Kai; Hallett, Mark; Slobounov, Semyon

doi:10.1007/s11682-014-9316-x

Cited by 66 publications

(94 citation statements)

References 39 publications

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“…While behavioral changes in response to subconcussive head impacts are difficult to measure, evidence coupled with neuroimaging data suggest that the ocular-motor system is particularly vulnerable and sensitive to head impacts. 19,38,39,41 Our data provide evidence of cumulative defect in the ocular NPC, and these changes may be head impact frequency-and magnitude-dependent. After a 3-week rest period, NPC normalized to the baseline.…”

Section: Discussionmentioning

confidence: 64%

Association of Football Subconcussive Head Impacts With Ocular Near Point of Convergence

et al. 2016

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IMPORTANCE An increased understanding of the relationship between subconcussive head impacts and near point of convergence (NPC) ocular-motor function may be useful in delineating traumatic brain injury.OBJECTIVE To investigate whether repetitive subconcussive head impacts during preseason football practice cause changes in NPC. DESIGN, SETTING, AND PARTICIPANTSThis prospective, observational study of 29 National Collegiate Athletic Association Division I football players included baseline and preseason practices (1 noncontact and 4 contact), and postseason follow-up and outcome measures were obtained for each time. An accelerometer-embedded mouthguard measured head impact kinematics. Based on the sum of head impacts from all 5 practices, players were categorized into lower (n = 7) or higher (n = 22) impact groups.EXPOSURES Players participated in regular practices, and all head impacts greater than 10g from the 5 practices were recorded using the i1Biometerics Vector mouthguard (i1 Biometrics Inc). MAIN OUTCOMES AND MEASURES Near point of convergence measures and symptom scores.RESULTS A total of 1193 head impacts were recorded from 5 training camp practices in the 29 collegiate football players; 22 were categorized into the higher-impact group and 7 into the lower-impact group. There were significant differences in head impact kinematics between lower-and higher-impact groups (number of impacts, 6 vs 41 [lower impact minus higher impact = 35; 95% CI, 21-51; P < .001]; linear acceleration, 99g vs 1112g [lower impact minus higher impact= 1013; 95% CI, 621 -1578; P < .001]; angular acceleration, 7589 radian/s 2 vs 65 016 radian/s 2 [lower impact minus higher impact= 57 427; 95% CI , 31 123-80 498; P < .001], respectively). The trajectory and cumulative burden of subconcussive impacts on NPC differed by group (F for group × linear trend 1, 238 = 12.14, P < .001 and F for group × quadratic trend 1, 238 = 12.97, P < .001). In the higher-impact group, there was a linear increase in NPC over time (B for linear trend, unstandardized coefficient [SE]: 0.76 [0.12], P < .001) that plateaued and resolved by postseason follow-up (B for quadratic trend [SE]: −0.06 [0.008], P < .001). In the lower-impact group, there was no change in NPC over time. Group differences were first observed after the first contact practice and remained until the final full-gear practice. No group differences were observed postseason follow-up. There were no differences in symptom scores between groups over time. CONCLUSIONS AND RELEVANCEAlthough asymptomatic, these data suggest that repetitive subconcussive head impacts were associated with changes in NPC. The increase in NPC highlights the vulnerability and slow recovery of the ocular-motor system following subconcussive head impacts. Changes in NPC may become a useful clinical tool in deciphering brain injury severity.

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Section: Discussionmentioning

confidence: 64%

Association of Football Subconcussive Head Impacts With Ocular Near Point of Convergence

et al. 2016

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“…The sequelae of concussion, a mild TBI, might be underestimated [19,20]. The World Health Organization Collaborating Center for Neurotrauma Task Force has estimated that up to 70%–90% of all traumatic brain injuries are treated as a mild TBI or concussion [21].…”

Section: Discussionmentioning

confidence: 99%

Increased Risk of Stroke in Patients of Concussion: A Nationwide Cohort Study

Liu

Huang

Chung

et al. 2017

IJERPH

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Long-term morbidities can develop after traumatic brain injury (TBI). Some studies have suggested that the risk of stroke is higher after TBI, but the association between concussion and stroke remains unclear. Using a national cohort, the authors analyzed the incidence of both hemorrhagic and ischemic strokes in patients with previous concussion. A representative cohort of approximately one million people was followed up for four years. Patients with new-onset concussion were identified (n = 13,652) as the concussion group. Subsequently, the incidence rates of later stroke events in the concussion group were compared to a sex-, age- and propensity score–matched comparison group (n = 13,652). The overall incidence rate of stroke in the concussion group was higher than that of the comparison group (9.63 versus 6.52 per 1000 person-years, p < 0.001). Significantly higher stroke risk was observed in the concussion group than in the comparison group (crude hazard ratio 1.48, p < 0.001; adjusted HR 1.65, p < 0.001). In the concussion group, the cumulative incidence rates of both ischemic stroke and hemorrhagic stroke were higher than those of the comparison group (8.9% vs. 5.8% and 2.7% vs. 1.6%, respectively, both p < 0.001). Concussion is an independent risk factor for both ischemic and hemorrhagic strokes. Prevention and monitoring strategies of stroke are therefore suggested for patients who have experienced concussion.

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“…The battery of oculomotor tasks included eye fixation, reflexive saccades, antisaccades, memory-guided saccades, self-paced saccades, and circular and sinusoidal smooth pursuit (see Johnson et al 4 and Heitger et al 5 for details). All saccades were performed in the horizontal plane.…”

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confidence: 99%

Follow-up evaluation of oculomotor performance with fMRI in the subacute phase of concussion

2015

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Objective: To expand on our previous study by performing a follow-up testing session in the subacute phase of injury for participants recently diagnosed with a concussion.Methods: A battery of oculomotor tests were administered to participants 30 days postconcussion while simultaneous fMRI was performed.Results: Three of the 7 oculomotor tasks (antisaccade, self-paced saccade, and memory-guided saccade) administered showed significant differences between the recently concussed group compared with normal volunteers. However, performance in these 3 tasks did show improvement from the acute phase of injury. The fMRI analysis revealed significant differences in brain activation patterns compared with normal volunteers, with the concussed group still demonstrating increased and larger areas of activation. Similar to the oculomotor performance, the fMRI analysis showed that at 30 days postinjury, the concussed group more closely mirrored that of the normal volunteer group compared with at 7 days following insult.Conclusions: Even at 30 days postinjury, and despite being clinically asymptomatic, advanced techniques are able to detect subtle lingering alterations in the concussed brain. Therefore, progressive neuroimaging techniques such as fMRI in conjunction with assessment of oculomotor performance may be beneficial in clinical management of concussion. Concussion initiates complex sequelae that produce disturbances in brain function and numerous somatic and cognitive symptoms.1 The majority of sports-related concussions demonstrate spontaneous recovery and resolution of clinical symptoms within 10 days postinjury.2 However, more advanced technologies have highlighted subtle changes and nuances in brain morphology, physiology, and function following concussion even though participants have returned to baseline on clinical measures. The direct relationship between the functional integrity of the brain and corresponding eye movements makes testing of oculomotor behavior a potential tool to allow for objective measures and inferences on brain integrity postconcussion.3 Given that concussion can disrupt multiple brain functional networks, including the oculomotor control networks, our previous study focused on the acute effects of concussion by having participants perform a battery of oculomotor tests while simultaneously undergoing fMRI. Behavioral results revealed that concussed participants performed worse in all oculomotor tasks and had increased fMRI recruitment and larger areas of activation.Here, we performed a follow-up to this study in the subacute phase of concussive injury. Based on our previous findings, we hypothesized that the more complex oculomotor tasks would demonstrate significant behavioral differences that coincide with increased activation areas and patterns. We also expected to still see impaired oculomotor performance, albeit less pronounced than in the acute phase of injury.

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Functional neuroimaging of acute oculomotor deficits in concussed athletes

Cited by 66 publications

References 39 publications

Association of Football Subconcussive Head Impacts With Ocular Near Point of Convergence

Association of Football Subconcussive Head Impacts With Ocular Near Point of Convergence

Increased Risk of Stroke in Patients of Concussion: A Nationwide Cohort Study

Follow-up evaluation of oculomotor performance with fMRI in the subacute phase of concussion

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