Acute and subacute changes in neural activation during the recovery from sport-related concussion.

To study the natural recovery from sports concussion, 12 concussed high school football athletes and 12 matched uninjured teammates were evaluated with symptom rating scales, tests of postural balance and cognition, and an event-related fMRI study during performance of a load-dependent working memory task at 13 h and 7 weeks following injury. Injured athletes showed the expected postconcussive symptoms and cognitive decline with decreased reaction time (RT) and increased RT variability on a working memory task during the acute period and an apparent full recovery 7 weeks later. Brain activation patterns showed decreased activation of right hemisphere attentional networks in injured athletes relative to controls during the acute period with a reversed pattern of activation (injured > controls) in the same networks at 7 weeks following injury. These changes coincided with a decrease in self-reported postconcussive symptoms and improved cognitive test performance in the injured athletes. Results from this exploratory study suggest that decreased activation of right hemisphere attentional networks mediate the cognitive changes and postconcussion symptoms observed during the acute period following concussion. Conversely, improvement in cognitive functioning and postconcussive symptoms during the subacute period may be mediated by compensatory increases in activation of this same attentional network.

Withdrawal of life support in critically ill neurosurgical patients and in-hospital death after discharge from the neurosurgical intensive care unit. Clinical article.

OBJECT: The aim of this study was to examine the variables influencing the mode and location of death in patients admitted to a neurosurgical intensive care unit (NICU), including the participation of a newly appointed neurointensivist (NI). METHODS: Data from all patients admitted to a university hospital NICU were prospectively collected and compared between 2 consecutive 19-month periods before and after the appointment of an NI. RESULTS: One thousand eighty-seven patients were admitted before and 1279 after the NI's appointment. The withdrawal of life support (WOLS) occurred in 52% of all cases of death. Death following WOLS compared with survival was independently associated with an older patient age (OR 1.04/year, 95% CI 1.03-1.05), a higher University Hospitals Consortium (UHC) expected mortality rate (OR 1.05/%, 95% CI 1.04-1.07), transfer from another hospital (OR 3.7, 95% CI 1.6-8.4) or admission through the emergency department (OR 5.3, 95% CI 2.4-12), admission to the neurosurgery service (OR 7.5, 95% CI 3.2-17.6), and diagnosis of an ischemic stroke (OR 5.4, 95% CI 1.4-20.8) or intracerebral hemorrhage (OR 5.7, 95% CI 1.9-16.7). On discharge from the NICU, 54 patients died on the hospital ward (2.7% mortality rate). A younger patient age (OR 0.94/year, 95% CI 0.92-0.96), higher UHC-expected mortality rate (OR 1.01/%, 95% CI 1-1.03), and admission to the neurosurgery service (OR 9.35, 95% CI 1.83-47.7) were associated with death in the NICU rather than the ward. There was no association between the participation of an NI and WOLS or ward mortality rate. CONCLUSIONS: The mode and location of death in NICU-admitted patients did not change after the appointment of an NI. Factors other than the participation of an NI-including patient age and the severity and type of neurological injury-play a significant role in the decision to withdraw life support in the NICU or dying in-hospital after discharge from the NICU.

Traumatic brain injury after frontal crashes: relationship with body mass index.

BACKGROUND: Previous studies had demonstrated that injury severity and risk of death after motor-vehicle crashes are related to human body characteristics. The purpose of this study was to clarify the relationship between body mass index (BMI) and head injury severity in front seat passengers after a frontal collision. METHODS: Data from all front seat occupants with at least one injury, older than 16 years old involved in a frontal collision from 1993 to 2005 were retrieved from the National Automotive Sampling System (NASS) database. Patient and collision characteristics were analyzed. Two cohorts were defined according to BMI < or > or =30 kg/m2. RESULTS: A total of 6,977 patients were included in this study, 5,918 (85%) had complete data on weight and height. Patient's mean age was 37 +/- 18 years old, the median ISS was 6, interquartile range (IQR) 15, and 61% were men. The mortality rate was positively associated to the crash delta velocity (DV) (p < 0.0001). The use of restraint system reduced the risk of death (p = 0.01). There was a significant increase in fatal outcome (p < 0.0001; RR 1.84 95% CI 1.61-2.1) and injury severity (ISS >25 p < 0.0001; RR 1.36 95% CI 1.19-1.54) in the obese cohort. Obese patients had higher chances of having a maximum head injury (Abbreviated Injury Score head = 6) than those not obese (p = 0.003; RR 1.97 95% CI 1.52-2.55). CONCLUSION: Obese passengers are more likely to suffer a more severe head trauma after a frontal collision. Further studies with computational models are needed to determine the precise role of BMI on brain injury-related biomechanical metrics.

Association of contact loading in diffuse axonal injuries from motor vehicle crashes.

BACKGROUND: Although studies have been conducted to analyze brain injuries from motor vehicle crashes, the association of head contact has not been fully established. This study examined the association in occupants sustaining diffuse axonal injuries (DAIs). METHODS: The 1997 to 2006 motor vehicle Crash Injury Research Engineering Network database was used. All crash modes and all changes in velocity were included; ejections and rollovers were excluded; injuries to front and rear seat occupants with and without restraint use were considered. DAI were coded in the database using Abbreviated Injury Scale 1990. Loss of consciousness was included and head contact was based on medical- and crash-related data. RESULTS: Sixty-seven occupants with varying ages were coded with DAI. Forty-one adult occupants (mean, 33 years of age, 171-cm tall, 71-kg weight; 30 drivers, 11 passengers) were analyzed. Mean change in velocity was 41.2 km/h and Glasgow Coma Scale score was 4. There were 33 lateral, 6 frontal, and 2 rear crashes with 32 survivors and 9 were fatalities. Two occupants in the same crash did not sustain DAI. Although skull fractures and scalp injuries occurred in some impacts, head contact was identified in all frontal, rear, and far side, and all but one nearside crashes. CONCLUSIONS: Using a large sample size of occupants sustaining DAI in 1991 to 2006 model year vehicles, DAI occurred more frequently in side than frontal crashes, is most commonly associated with impact load transfer, and is not always accompanied by skull fractures. The association of head contact in >95% of cases underscores the importance of evaluating crash-related variables and medical information for trauma analysis. It would be prudent to include contact loading in addition to angular kinematics in the analysis and characterization of DAI.

Influence of angular acceleration-deceleration pulse shapes on regional brain strains.

Recognizing the association of angular loading with brain injuries and inconsistency in previous studies in the application of the biphasic loads to animal, physical, and experimental models, the present study examined the role of the acceleration-deceleration pulse shapes on region-specific strains. An experimentally validated two-dimensional finite element model representing the adult male human head was used. The model simulated the skull and falx as a linear elastic material, cerebrospinal fluid as a hydrodynamic material, and cerebrum as a linear viscoelastic material. The angular loading matrix consisted coronal plane rotation about a center of rotation that was acceleration-only (4.5 ms duration, 7.8 krad/s/s peak), deceleration-only (20 ms, 1.4 krad/s/s peak), acceleration-deceleration, and deceleration-acceleration pulses. Both biphasic pulses had peaks separated by intervals ranging from 0 to 25 ms. Principal strains were determined at the corpus callosum, base of the postcentral sulcus, and cerebral cortex of the parietal lobe. The cerebrum was divided into 17 regions and peak values of average maximum principal strains were determined. In all simulations, the corpus callosum responded with the highest strains. Strains were the least under all simulations in the lower parietal lobes. In all regions peak strains were the same for both monophase pulses suggesting that the angular velocity may be a better metric than peak acceleration or deceleration. In contrast, for the biphasic pulse, peak strains were region- and pulse-shape specific. Peak values were lower in both biphasic pulses when there was no time separation between the pulses than the corresponding monophase pulse. Increasing separation time intervals increased strains, albeit non-uniformly. Acceleration followed by deceleration pulse produced greater strains in all regions than the other form of biphasic pulse. Thus, pulse shape appears to have an effect on regional strains in the brain.

New rat model for diffuse brain injury using coronal plane angular acceleration.

A new experimental model was developed to induce diffuse brain injury (DBI) in rats through pure coronal plane angular acceleration. An impactor was propelled down a guide tube toward the lateral extension of the helmet fixture. Upon impactor-helmet contact, helmet and head were constrained to rotate in the coronal plane. In the present experimental series, the model was optimized to generate rotational kinematics necessary for concussion. Twenty-six rats were subjected to peak angular accelerations of 368 +/- 30 krad/sec2 (mean +/- standard deviation) with 2.1 +/- 0.5-msec durations. Following rotational loading, unconsciousness was defined as time between reversal agent administration and return of corneal reflex. All experimental rats demonstrated transient unconsciousness lasting 8.8 +/- 3.7 min that was significantly longer than control rats. Macroscopic damage was noted in 51% of experimental animals: 38% subarachnoid hemorrhage, and 15% intraparenchymal lesion. Microscopic analysis indicated no evidence of axonal swellings at sacrifice times of 24, 48, 72, and 96 h. All rats survived rotational loading without skull fracture. Injuries were classified as concussion based on transient unconsciousness, scaled biomechanics, limited macroscopic damage, and minimal histological abnormalities. The experimental methodology remains adjustable, permitting investigation of increasing DBI severities through modulation of model parameters, and inclusion of further functional and histological outcome measures.

Experimental model for civilian ballistic brain injury biomechanics quantification.

Biomechanical quantification of projectile penetration using experimental head models can enhance the understanding of civilian ballistic brain injury and advance treatment. Two of the most commonly used handgun projectiles (25-cal, 275 m/s and 9 mm, 395 m/s) were discharged to spherical head models with gelatin and Sylgard simulants. Four ballistic pressure transducers recorded temporal pressure distributions at 308kHz, and temporal cavity dynamics were captured at 20,000 frames/second (fps) using high-speed digital video images. Pressures ranged from 644.6 to -92.8 kPa. Entry pressures in gelatin models were higher than exit pressures, whereas in Sylgard models entry pressures were lower or equivalent to exit pressures. Gelatin responded with brittle-type failure, while Sylgard demonstrated a ductile pattern through formation of micro-bubbles along projectile path. Temporary cavities in Sylgard models were 1.5-2x larger than gelatin models. Pressures in Sylgard models were more sensitive to projectile velocity and diameter increase, indicating Sylgard was more rate sensitive than gelatin. Based on failure patterns and brain tissue rate-sensitive characteristics, Sylgard was found to be an appropriate simulant. Compared with spherical projectile data, full-metal jacket (FMJ) projectiles produced different temporary cavity and pressures, demonstrating shape effects. Models using Sylgard gel and FMJ projectiles are appropriate to enhance understanding and mechanisms of ballistic brain injury.

Biomechanics of side impact: injury criteria, aging occupants, and airbag technology.

This paper presents a survey of side impact trauma-related biomedical investigations with specific reference to certain aspects of epidemiology relating to the growing elderly population, improvements in technology such as side airbags geared toward occupant safety, and development of injury criteria. The first part is devoted to the involvement of the elderly by identifying variables contributing to injury including impact severity, human factors, and national and international field data. This is followed by a survey of various experimental models used in the development of injury criteria and tolerance limits. The effects of fragility of the elderly coupled with physiological changes (e.g., visual, musculoskeletal) that may lead to an abnormal seating position (termed out-of-position) especially for the driving population are discussed. Fundamental biomechanical parameters such as thoracic, abdominal and pelvic forces; upper and lower spinal and sacrum accelerations; and upper, middle and lower chest deflections under various initial impacting conditions are evaluated. Secondary variables such as the thoracic trauma index and pelvic acceleration (currently adopted in the United States Federal Motor Vehicle Safety Standards), peak chest deflection, and viscous criteria are also included in the survey. The importance of performing research studies with specific focus on out-of-position scenarios of the elderly and using the most commonly available torso side airbag as the initial contacting condition in lateral impacts for occupant injury assessment is emphasized.

Lateral impact injuries with side airbag deployments--a descriptive study.

The present study was designed to provide descriptive data on side impact injuries in vehicles equipped with side airbags using the United States National Automotive Sampling System (NASS). The database was queried with the constraint that all vehicles must adhere to the Federal Motor Vehicle Safety Standards FMVSS 214, injured occupants be in the front outboard seats with no rollovers or ejections, and side impacts airbags be deployed in lateral crashes. Out of the 7812 crashes in the 1997-2004 weighted NASS files, AIS > or = 2 level injuries occurred to 5071 occupants. There were 3828 cases of torso-only airbags, 955 cases of torso-head bag combination, and 288 inflatable tubular structure/curtain systems. Side airbags were not attributed to be the cause of head or chest injury to any occupant at this level of severity. The predominance of torso-only airbags followed by torso-head airbag combination reflected vehicle model years and changing technology. Head and chest injuries were coupled for the vast majority of occupants with injuries to more than one body region. Comparing literature data for side impacts without side airbag deployments, the presence of a side airbag decreased AIS=2 head, chest, and extremity injuries when examining raw data incidence rates. Although this is the first study to adopt strict inclusion-exclusion criteria for side crashes with side airbag deployments, future studies are needed to assess side airbag efficacy using datasets such as matched-pair occupants in side impacts.

Impact of a neurointensivist on outcomes in patients with head trauma treated in a neurosciences intensive care unit.

OBJECT: The aim of this study was to evaluate the impact of a newly appointed neurointensivist on outcomes in head-injured patients in the neurological/neurosurgical intensive care unit (NICU). METHODS: The mortality rate, length of stay (LOS), and discharge disposition of all patients with head trauma who had been admitted to a 10-bed tertiary care university hospital NICU were compared between two 19-month periods, before and after the appointment of a neurointensivist. Data regarding these patients were collected using the hospital database and the University HealthSystem Consortium (UHC) database. Samples of medical records were reviewed for Glasgow Coma Scale (GCS) score documentation. The authors analyzed data pertaining to 328 patients before and 264 after the neurointensivist's appointment. The unadjusted mean in-hospital mortality rate increased 1.1% in the after period, but this increase was significantly lower compared with the UHC-based expected increase of 8.1% in the mortality rate during the same period (p < 0.0001). The unadjusted mean mortality rate in the NICU decreased from 13.4 to 12.9% (relative mortality rate reduction 4%) and the mean NICU LOS increased from 3.1 to 3.6 days (relative NICU LOS increase 16%), both nonsignificantly. A 51% reduction in the NICU-associated mortality rate (p = 0.01), a 12% shorter hospital LOS (p = 0.026), and 57% greater odds of being discharged to home or to rehabilitation (p = 0.009) were found in the after period in multivariate models after controlling for baseline differences between the two time periods. Better documentation of the GCS score by the NICU team was also found in the after period (from 60.4 to 82%, p = 0.02). CONCLUSIONS: The institution of a neurointensivist-led team model had an independent, positive impact on patient outcomes, including a lower NICU-associated mortality rate and hospital LOS, improved disposition, and better chart documentation.

Brain strains in vehicle impact tests.

The purpose of this research was to use vehicle impact test data and parametric finite element analysis to study the contribution of translational accelerations (TransAcc) and rotational accelerations (RotAcc) on strain-induced head injuries. Acceleration data were extracted from 33 non-contact vehicle crash tests conducted by the US Department of Transportation, National Highway Traffic Safety Administration. A human finite element head model was exercised using head accelerations from the nine accelerometer package placed inside the driver dummy in these tests. Three scenarios were parameterized: both TransAcc and RotAcc, only TransAcc, and only RotAcc to demonstrate the contribution of these accelerations on brain injury. Brain strains at multiple elements, cumulative strain damage, dilatation damage, and relative motion damage data were compared. Rotational accelerations contributed to more than 80% of the brain strain. Other injury metrics also supported this finding. These findings did not depend on the crash mode, peak amplitude of translational acceleration (29 to 120 g), peak amplitude of rotational acceleration (1.3 to 9.4 krad/s ( 2 ) ) or HIC (68-778). Rotational accelerations appeared to be the major cause of strain-induced brain injury.

Effect of image uncertainty on the dosimetry of trigeminal neuralgia irradiation.

OBJECTIVE: Our objective was to quantify the uncertainty in localization of the trigeminal nerve (TGN) with magnetic resonance imaging (MRI) and computed tomography (CT) and to determine the effect of this uncertainty on gamma-knife dose delivery. METHODS: An MR/CT test phantom with 9, 0.6-mm diameter, copper rings was devised. The absolute ring positions in stereotactic space were determined by the angiographic module of the LGP software. The standard deviation, sigma, in the difference between the absolute and MR-measured or CT-measured coordinates of the rings was determined. The trigeminal nerve in 52 previously treated patients was contoured and expanded by 1sigma and 2sigma margins to model the uncertainty in the location of the nerve. For gamma-knife treatment, a single isocenter was used and was located at the distal cisternal portion of the trigeminal nerve root. Irradiation methods included a 4-mm collimator, 90 Gy to isocenter and a 4&8-mm collimator, 70 Gy to isocenter. A patient outcome survey that sampled pain relief and morbidity was done. RESULTS: The MR coordinate sigma was 0.7 mm left-right, 0.8 mm anterior-posterior, and 0.6 mm superior-inferior, and the CT coordinate sigma was 0.4 mm left-right, 0.2 mm anterior-posterior, and 0.2 mm superior-inferior. A 45% higher dose line covered the TGN with the 4&8-mm method. No significant increase in pain reduction or morbidity occurred. CONCLUSIONS: The uncertainty of target location by MRI is more than twice that found in CT imaging. The 4&8-mm collimator method covers the trigeminal root cross section with a higher isodose line than does the 4-mm method. This higher dose did not significantly reduce pain or increase morbidity.

Temporal cavity and pressure distribution in a brain simulant following ballistic penetration.

To study ballistic brain injury biomechanics, two common civilian full metal jacket handgun projectiles (25-caliber and 9-mm) were discharged into a transparent brain simulant (Sylgard gel). Five pressure transducers were placed at the entry (two), exit (two) and center (one) of the simulant. High-speed digital video photography (20,000 frames/second) was used to capture the temporal cavity pulsation. Pressure histories and high-speed video images were synchronized with a common trigger. Pressure data were sampled at 308 kHz. The 25-caliber projectile had an entry velocity of 238 m/s and exit velocity of 170 m/s. The 9-mm projectile had an entry velocity of 379 m/s and exit velocity of 259 m/s. Kinetic energies lost during penetration were 45.2 J for the 25-caliber projectile and 283.7 J for the 9-mm. Size of temporary cavities and pressures were dependent on projectile size and velocity. The 9-mm projectile created temporary cavities 1.5 times larger in size and lasted 1.5 times longer than the 25-caliber projectile. The 9-mm projectile had pressures three times higher than the 25-caliber projectile. Pressure differences between the center location and surrounding regions were approximately 1.4 times higher and lasted about 1.6 times longer in the 9- mm projectile than the 25-caliber projectile. Collapsing of the temporary cavity drew the brain simulant toward the center of the temporary cavity and created negative pressures of approximately -0.5 atmospheric pressure in the surrounding region. Pressures reached approximately +2 atmospheric pressure when temporary cavities collapsed. These quantified data may assist in understanding injury biomechanics and management of penetration brain trauma.

Risk of pediatric head injury after motor vehicle accidents.

OBJECT: Injury to the brain as a result of motor vehicle accidents (MVAs) represents a frequent cause of pediatric disability. The authors analyze the correlation between the relative risk of pediatric brain injury and the use of child safety seats (CSSs). METHODS: A national database of MVAs was examined to provide data for the analysis of four age categories (infant, toddler, young child, and adolescent) and four restraint categories (unrestrained, properly restrained, improperly restrained, and other). The Abbreviated Injury Scale (AIS) was used to assess the severity of head injury; children with no injuries and children with moderate-to-maximum head injuries were evaluated. The data confirm that proper use of a CSS substantially increases the likelihood of not sustaining head injury in an MVA. The data are most dramatic for infants (the likelihood of sustaining no head injury was 15.2% for unrestrained infants compared with 92.8% for properly restrained infants) but the protective effect is seen in all age categories, with the least difference observed in the adolescent category. For children who sustain a moderate-to-maximum head injury, proper use of a CSS reduces the incidence of injury, again most dramatically for the infant category (unrestrained infants had a 7% risk of moderate-to-maximum head injury compared with only 0.5% for properly restrained infants). CONCLUSIONS: Improvements in CSSs have reduced the risk of moderate-to-maximum head injuries in children of all age categories. Overall, a CSS is most protective for the infant and toddler categories. The improperly restrained child still has substantial protection, although the properly restrained child has more. Detailed parental education regarding appropriate restraint system installation and use should be required.

Localized cervical facet joint kinematics under physiological and whiplash loading.

OBJECT: Although facet joints have been implicated in the whiplash injury mechanism, no investigators have determined the degree to which joint motions in whiplash are nonphysiological. The purpose of this investigation was to quantify the correlation between facet joint and segmental motions under physiological and whiplash loading. METHODS: Human cadaveric cervical spine specimens were exercise tested under physiological extension loading, and intact human head-neck complexes were exercise tested under whiplash loading to correlate the localized component motions of the C4-5 facet joint with segmental extension. Facet joint shear and distraction kinematics demonstrated a linear correlation with segmental extension under both loading modes. Facet joints responded differently to whiplash and physiological loading, with significantly increased kinematics for the same-segmental angulation. The limitations of this study include removal of superficial musculature and the limited sample size for physiological testing. CONCLUSIONS: The presence of increased facet joint motions indicated that synovial joint soft-tissue components (that is, synovial membrane and capsular ligament) sustain increased distortion that may subject these tissues to a greater likelihood of injury. This finding is supported by clinical investigations in which lower cervical facet joint injury resulted in similar pain patterns due to the most commonly reported whiplash symptoms.

Field data on head injuries in side airbag vehicles in lateral impact.

Field data on side airbag deployments in lateral crashes and head injuries have largely remained anecdotal. Consequently, the purpose of this research was to report head injuries in lateral motor vehicle impacts. Data from the National Automotive Sampling System files were extracted from side impacts associated with side airbag deployments. Matched pairs with similar vehicle characteristics but without side airbags were also extracted. All data were limited to the United States Federal Motor vehicle Safety Standards FMVSS 214 compliant vehicles so that the information may be more effectively used in the future. In this study, some fundamental analyses are presented regarding occupant- and vehicle-related parameters.

Quantitative pupillometry, a new technology: normative data and preliminary observations in patients with acute head injury. Technical note.

The authors prospectively used a new hand-held point-and-shoot pupillometer to assess pupillary function quantitatively. Repetitive measurements were initially made in more than 300 healthy volunteers ranging in age from 1 to 87 years, providing a total of 2,432 paired (alternative right eye, left eye) measurements under varying light conditions. The authors studied 17 patients undergoing a variety of nonintracranial, nonophthalmological, endoscopic, or surgical procedures and 20 seniors in a cardiology clinic to learn more about the effects of a variety of drugs. Additionally, the authors carried out detailed studies in 26 adults with acute severe head injury in whom intracranial pressure (ICP) was continuously monitored. Finally, five patients suffering from subarachnoid hemorrhage were also studied. Quantitative pupillary measurements could be reliably replicated in the study participants. In healthy volunteers the resting pupillary aperture averaged 4.1 mm and the minimal aperture after stimulation was 2.7 mm, resulting in a 34% change in pupil size. Constriction velocity averaged 1.48 +/- 0.33 mm/second. Pupillary symmetry was striking in both healthy volunteers and patients without intracranial or uncorrected visual acuity disorders. In the 2,432 paired measurements in healthy volunteers, constriction velocity was noted to fall below 0.85 mm/second on only 33 occasions and below 0.6 mm/second on eight occasions (< one in 310 observations). In outpatients, the reduction in constriction velocity was observed when either oral or intravenous narcotic agents and diazepam analogs were administered. These effects were transient and always symmetrical. Among the 26 patients with head injuries, eight were found to have elevations of ICP above 20 mm Hg and pupillary dynamics in each of these patients remained normal. In 13 patients with a midline shift greater than 3 mm, elevations of ICP above 20 mm Hg, when present for 15 minutes, were frequently associated with a reduction in constriction velocity on the side of the mass effect to below 0.6 mm/second (51% of 156 paired observations). In five patients with diffuse brain swelling but no midline shift, a reduction in constriction velocities did not generally occur until the ICP exceeded 30 mm Hg. Changes in the percentage of reduction from the resting state following stimulation were always greater than 10%, even in patients receiving large doses of morphine and propofol in whom the ICP was lower than 20 mm Hg. Asymmetry of pupillary size greater than 0.5 mm was observed infrequently (< 1%) in healthy volunteers and was rarely seen in head-injured patients unless the ICP exceeded 20 mm Hg. Pupillometry is a reliable technology capable of providing repetitive data on quantitative pupillary function in states of health and disease.

Future directions in brain injury research.

This paper reviews the potential future directions that are important for brain injury research, especially with regard to concussion. The avenues of proposed research are categorized according to current concepts of concussion, types of concussion, and a global schema for globally reducing the burden of concussion.

Neuropathological findings in disabled survivors of a head injury.

We investigated how the occurrence and severity of the main neuropathological types of traumatic brain injury (TBI) influenced the severity of disability after a head injury. Eighty-five victims, each of whom had lived at least a month after a head injury but then died, were studied. Judged by the Glasgow Outcome Scale (GOS), before death 35 were vegetative, 30 were severely and 20 were moderately disabled. Neuropathological assessment showed that 71 (84%) victims had sustained cerebral contusions, 49 (58%) had diffuse axonal injury (DAI), 57 (67%), had ischemic brain damage (IBD), 58 (68%) had symmetrical ventricular enlargement, and in 47 (55%) intracranial pressure (ICP) had been increased. Thirty-five (41%) had undergone evacuation of an intracranial hematoma. Brainstem damage was seen in only 11 (13%). Analysis (χ(2) test for trends) of the relationship between these features and outcome showed that findings of DAI, raised ICP, thalamic damage, or ventricular enlargement (all p<0.005), and IBD (p=0.04) were associated with an increasingly worse outcome. Conversely, moderate or severe contusions (p=0.001) were increasingly associated with better outcomes, and evacuation of a hematoma was associated (p=0.001) with outcomes likely to be better than vegetative. We conclude that diffuse or multifocal neuropathological patterns of TBI from primary axonal injury or secondary ischemic damage are most likely to be associated with the most severely impaired outcomes after a head injury.

Severe-to-fatal head injuries in motor vehicle impacts.

Severe-to-fatal head injuries in motor vehicle environments were analyzed using the United States Crash Injury Research and Engineering Network database for the years 1997-2006. Medical evaluations included details and photographs of injury, and on-scene, trauma bay, emergency room, intensive care unit, radiological, operating room, in-patient, and rehabilitation records. Data were synthesized on a case-by-case basis. X-rays, computed tomography scans, and magnetic resonance images were reviewed along with field evaluations of scene and photographs for the analyses of brain injuries and skull fractures. Injuries to the parenchyma, arteries, brainstem, cerebellum, cerebrum, and loss of consciousness were included. In addition to the analyses of severe-to-fatal (AIS4+) injuries, cervical spine, face, and scalp trauma were used to determine the potential for head contact. Fatalities and survivors were compared using nonparametric tests and confidence intervals for medians. Results were categorized based on the mode of impact with a focus on head contact. Out of the 3178 medical cases and 169 occupants sustaining head injuries, 132 adults were in frontal (54), side (75), and rear (3) crashes. Head contact locations are presented for each mode. A majority of cases clustered around the mid-size anthropometry and normal body mass index (BMI). Injuries occurred at change in velocities (DeltaV) representative of US regulations. Statistically significant differences in DeltaV between fatalities and survivors were found for side but not for frontal impacts. Independent of the impact mode and survivorship, contact locations were found to be superior to the center of gravity of the head, suggesting a greater role for angular than translational head kinematics. However, contact locations were biased to the impact mode: anterior aspects of the frontal bone and face were involved in frontal impacts while temporal-parietal regions were involved in side impacts. Because head injuries occur at regulatory DeltaV in modern vehicles and angular accelerations are not directly incorporated in crashworthiness standards, these findings from the largest dataset in literature, offer a field-based rationale for including rotational kinematics in injury assessments. In addition, it may be necessary to develop injury criteria and evaluate dummy biofidelity based on contact locations as this parameter depended on the impact mode. The current field-based analysis has identified the importance of both angular acceleration and contact location in head injury assessment and mitigation.