Research: Long-Term Objectives
To develop strategies for reducing the incidence and severity of mild traumatic brain injury (mTBI) in the population that can be translated to clinical practice. This includes continued hypothesis-driven research, development of novel protective equipment, diagnostic equipment for field use and other healthcare settings, neuropharmacological strategies, novel strategies for return to activity and educational tools for disseminating information about mTBI, its evaluation and prevention. |
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Research Aims | |||
The HIT System™ |
Clinical Research Protocols |
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We hypothesize that head acceleration due to impact is predictive of the type and severity of brain injury, and correlated to specific clinical measures of brain injury. |
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Specific Aims |
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The HIT System™ | |||
Sports provide an Ideal Environment for Monitoring Head Impacts Real-time monitoring and recording of all significant head impacts using the Head Impact Telemetry (HIT) System™. HIT System™ computes head acceleration, impact duration and impact location for multiple athletes simulatiously to alert team physicians and athletic trainers to potentially injurious impacts. Impacts are immediately transmitted (via radio frequence) to a Sideline Controller which records, processes and stores the data. The Head Impact Telemetry (HIT) System™ monitors, records and processes head impacts in real-time during all practices and competitions. The HIT System™ measures impact magnitude, location and duration. The HIT System™ is the first and only commercially available system that can measure head accelerations (impacts) in real-time during games and practices. The HIT System™ sensor/encoder package contains impact sensors, a processor, and a transmitter. (A commercial version of this product for football use will be available from Riddell this fall.) The HIT System™ transforms a helmet or headgear into a head-impact monitor. A microprocessor-based data collector receives impact data continuously from encoders that can be hundreds of meters away. The HIT System™ can monitor dozens of athletes or soldiers simultaneously. Our proprietary software analyzes those data and sends a warning via an alert pager if any impact has a potentially injurious profile. Multiple athletes can be monitored simultaneously. The data collector stores all of the key signatures of each impact — peak linear acceleration, rotational acceleration, impact duration and location, etc. — with a time stamp for future analysis. The data can be accessed to compute commonly used head-impact severity measures (HIC, GSI, etc.). The HIT System™ reflects more than a decade of research (supported in part by the National Center for Medical Rehabilitation Research at the National Institutes of Health). HITS has been tested in the crucible of NFL, college and high school football stadiums and practice fields since 2004. Using the HIT System, we have recorded over two million impacts and corresponding data on head injuries. Simbex and our research partners are using the analysis of these data to shed new light on the biomechanical causes of mild traumatic brain injuries (mTBI). This research may lead to advancements in protective equipment or other injury reduction strategies.
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Clinical Research ProtocolsCombining current concussion management strategies with emerging technology to diagnose, treat and evaluate concussive impacts in athletes. Clinical assessments include: symptomatology, neurocognitive function, brain imaging (fMRI/DTI) and postural stability. | |||
Neurocognitive Assessment:ImPACT© WebsiteImPACT© - Computerized Neuropsychological Exam: ImPACT© (Immediate Post-concussion Assessment and Cognitive Test) is a computerized neuropsychological test battery specifically designed and validated for use as a tool for sports-related concussion that takes approximately 20 minutes to complete[1]. ImPACT consists of six cognitive test modules, including tests for verbal memory, visual working memory, attention, visual attention span, processing speed, and choice reaction time. Composite scores are computed for memory, reaction time, and processing speed, and postconcussion symptom data selected from 22 commonly described symptoms (based on the consensus from the 1st International Conference on Concussion in Sports, Vienna 2001 - used by NFL and NHL). ImPACT is administered at one preseason baseline time point and serially at three post-concussion time points: within 24-48 hours post-injury, and 7 days or symptom resolution. |
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Neuropsychological Test BatteryParticipants undergo approximately 2.5 hours of neuropsychological (NP) testing. The tests were chosen to probe cognitive domains showing particular deficits in mTBI. Tests with alternate forms were chosen where available, to allow for repeat measures with minimal practice effect contamination, although this should be minimized given the 12 month interval between assessments. The battery assesses levels of estimated general intellectual function (Wide Range Achievement Test - 3rd Edition (WRAT-3 Green)), verbal learning and memory (California Verbal Learning Test II, CVLT II versions Standard, Alternate, and Research and Word Memory Test), visual memory (Brief Visiospatial Memory Test- Revised (BVMT-R)), reaction time and distractibility (Continuous Performance Task (CPT)), motor function and coordination,and psychomotor speed (Wechsler Adult Intelligence Scale, Digit Symbol Coding subtests and D-KEFS Trail Making subtests). In addition, a group of tests assessing working memory, executive function (Stroop, Controlled Oral Word Fluency Test (D-KEFS CFL/FAS) and Controlled Oral Word Categories (D-KEFS Animal/Boys and Clothing/Girls)) and attentional function (Paced Auditory Serial Additional Test, WAIS-III Letter Number Sequencing, ) are given. |
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Functional Magnetic Resonance Imaging (fMRI)Subjects undergo a structural scan sequence and 4 fMRI memory tasks: visual and verbal continuous recognition memory tasks (encoding and retrieval, with long and short delay memory), verbal and visual-spatial 3-back (Working Memory, vigilance, reaction time). The Dartmouth Advanced Neuroimaging Research Center, opened in December 2005, runs a research-dedicated Philips Acheiva 3.0T MR scanner, allowing us to run the proposed protocol at high field on this latest generation scanner. |
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Diffusion Tensor Imaging (DTI)Brain ImagingDiffusion Tensor Imaging (DTI) measures the diffusivity of water in a number of orientations. Its usefulness is based on the observation that water diffusivity is high along an axon's body and very low perpendicular to it -- axons function like long tubes, in other words — and that the observed values will vary with structural changes, such as axonal tearing or swelling. In practice, DTI measurements reflect the combined diffusions of tens of thousands of axons (and other tissues too) at each "voxel", or three dimensional sample region. The "diffusion tensor", a mathematical model of the diffusion, gives the best estimate of overall voxel diffusion behavior under the assumption that it can be modeled with a single diffusion ellipsoid. From diffusion tensors, images can be created of average or maximal diffusivity measurements, or of more complicated values such as the "fractional anisotropy" (FA), which is the degree to which diffusion ellipsoids exhibit isotropy (uniform diffusion in all directions) or anisotropy (diffusion limited to a particular direction). |
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Postural Stability and Balance Assessment
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Force PlateForce plate testing is conducted using an AccuSway Force Platform from AMTI. This test utilizes the same test protocol as the BESS test, running 3 trials on "firm ground" on the flat force plate, and the 3 "foam pad" trials with the Airex balance pad centered on the Force Plate. Testing is run using the AMTI Balance Clinic software program. Additional Force Plate testing with a military ISOBalance Force Plate is also being conducted for comparison. |
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On-Field Concussion Assessment
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