Ira R. Casson

Concussion in professional football: recovery of NFL and high school athletes assessed by computerized neuropsychological testing--Part 12.

OBJECTIVE: Acute recovery from concussion (mild traumatic brain injury) is assessed in samples of NFL and high school athletes evaluated within days of injury. METHODS: All athletes were evaluated within days of injury using a computer-based neuropsychological test and symptom inventory protocol. Test performance was compared to preinjury baseline levels of a similar but not identical group of athletes who had undergone preseason testing. Statistical analyses were completed using Multivariate Analysis of Variance (MANOVA). RESULTS: NFL athletes demonstrated a rapid neuropsychological recovery. As a group, NFL athletes returned to baseline performance in a week with the majority of athletes having normal performance two days after injury. High school athletes demonstrated a slower recovery than NFL athletes. CONCLUSION: Computer-based neuropsychological testing was used within the overall medical evaluation and care of NFL athletes. As found in a prior study using more traditional neuropsychological testing, NFL players did not demonstrate decrements in neuropsychological performance beyond one week of injury. High school players demonstrated more prolonged neuropsychological effects of concussion.

Concussion in professional football: brain responses by finite element analysis: part 9.

OBJECTIVE:Brain responses from concussive impacts in National Football League football games were simulated by finite element analysis using a detailed anatomic model of the brain and head accelerations from laboratory reconstructions of game impacts. This study compares brain responses with physician determined signs and symptoms of concussion to investigate tissue-level injury mechanisms. METHODS:The Wayne State University Head Injury Model (Version 2001) was used because it has fine anatomic detail of the cranium and brain with more than 300,000 elements. It has 15 different material properties for brain and surrounding tissues. The model includes viscoelastic gray and white brain matter, membranes, ventricles, cranium and facial bones, soft tissues, and slip interface conditions between the brain and dura. The cranium of the finite element model was loaded by translational and rotational accelerations measured in Hybrid III dummies from 28 laboratory reconstructions of NFL impacts involving 22 concussions. Brain responses were determined using a nonlinear, finite element code to simulate the large deformation response of white and gray matter. Strain responses occurring early (during impact) and mid-late (after impact) were compared with the signs and symptoms of concussion. RESULTS:Strain concentration “hot spots” migrate through the brain with time. In 9 of 22 concussions, the early strain “hot spots” occur in the temporal lobe adjacent to the impact and migrate to the far temporal lobe after head acceleration. In all cases, the largest strains occur later in the fornix, midbrain, and corpus callosum. They significantly correlated with removal from play, cognitive and memory problems, and loss of consciousness. Dizziness correlated with early strain in the orbital-frontal cortex and temporal lobe. The strain migration helps explain coup-contrecoup injuries. CONCLUSION:Finite element modeling showed the largest brain deformations occurred after the primary head acceleration. Midbrain strain correlated with memory and cognitive problems and removal from play after concussion. Concussion injuries happen during the rapid displacement and rotation of the cranium, after peak head acceleration and momentum transfer in helmet impacts.

Concussion in professional football: neuropsychological testing--part 6.

OBJECTIVE:The National Football League (NFL) neuropsychological testing program is reviewed, and neuropsychological test data are presented on various samples of NFL athletes who sustained concussion (mild traumatic brain injury, MTBI). METHODS:This study evaluated post-MTBI neuropsychological testing of NFL players from 1996 to 2001. All athletes completed a standardized battery of neuropsychological tests and underwent postinjury neuropsychological testing within a few days after concussion. Test scores were compared with baselines using analysis of variance for athletes having on-field memory dysfunction, three or more concussions, or 7+ days out from practice and play. RESULTS:The MTBI group did not display significant neuropsychological dysfunction relative to baseline scores within a few days of injury. However, a subsample of the injured athletes who displayed on-field memory dysfunction performed significantly more poorly on two of the memory tests. The neuropsychological test results of a group of athletes with a history of three or more MTBIs did not differ significantly compared with a group who had fewer than three concussions or compared with league-wide normative data. The neuropsychological performance of athletes who were out from full participation 7+ days was not significantly different from the group who returned to play within 7 days or the norms. CONCLUSION:Neuropsychological testing is used within the overall medical evaluation and care of NFL athletes. Players who experience MTBI generally demonstrate rapid recovery of neuropsychological performance, although poorer neuropsychological test results were related to on-field memory dysfunction. NFL players did not demonstrate evidence of neurocognitive decline after multiple (three or more) MTBIs or in those players out 7+ days. The data show that MTBI in this population is characterized by a rapid return of neuropsychological function in the days after injury.

Concussion in professional football: comparison with boxing head impacts--part 10.

OBJECTIVE: This study addresses impact biomechanics from boxing punches causing translational and rotational head acceleration. Olympic boxers threw four different punches at an instrumented Hybrid III dummy and responses were compared with laboratory-reconstructed NFL concussions. METHODS: Eleven Olympic boxers weighing 51 to 130 kg (112–285 lb) delivered 78 blows to the head of the Hybrid III dummy, including hooks, uppercuts and straight punches to the forehead and jaw. Instrumentation included translational and rotational head acceleration and neck loads in the dummy. Biaxial acceleration was measured in the boxer’s hand to determine punch force. High-speed video recorded each blow. Hybrid III head responses and finite element (FE) brain modeling were compared to similarly determined responses from reconstructed NFL concussions. RESULTS: The hook produced the highest change in hand velocity (11.0 ± 3.4 m/s) and greatest punch force (4405 ± 2318 N) with average neck load of 855 ± 537 N. It caused head translational and rotational accelerations of 71.2 ± 32.2 g and 9306 ± 4485 r/s2. These levels are consistent with those causing concussion in NFL impacts. However, the head injury criterion (HIC) for boxing punches was lower than for NFL concussions because of shorter duration acceleration. Boxers deliver punches with proportionately more rotational than translational acceleration than in football concussion. Boxing punches have a 65 mm effective radius from the head cg, which is almost double the 34 mm in football. A smaller radius in football prevents the helmets from sliding off each other in a tackle. CONCLUSION: Olympic boxers deliver punches with high impact velocity but lower HIC and translational acceleration than in football impacts because of a lower effective punch mass. They cause proportionately more rotational acceleration than in football. Modeling shows that the greatest strain is in the midbrain late in the exposure, after the primary impact acceleration in boxing and football.

Concussion in professional football: repeat injuries—Part 4

OBJECTIVE:A 6-year study was conducted to determine the signs, symptoms, and management of repeat concussion in National Football League players. METHODS:From 1996 to 2001, concussions were reported by 30 National Football League teams using a standardized reporting form filled out by team physicians with input from athletic trainers. Signs and symptoms were grouped by general symptoms, somatic complaints, cranial nerve effects, cognition problems, memory problems, and unconsciousness. Medical actions taken and management were recorded. RESULTS:Data were captured for 887 concussions in practices and games involving 650 players. A total of 160 players experienced repeat injury, with 51 having three or more concussions during the study period. The median time between injuries was 374.5 days, with only six concussions occurring within 2 weeks of the initial injury. Repeat concussions were more prevalent in the secondary (16.9%), the kick unit on special teams (16.3%), and wide receivers (12.5%). The ball return carrier on special teams (odds ratio [OR] = 2.08, P = not significant) and quarterbacks (OR = 1.92, P < 0.1) had elevated odds for repeat injury, followed by the tight end (OR = 1.24, P = not significant) and linebackers (OR = 1.22, P = not significant). There were similar signs and symptoms with single and repeat concussion, except for a higher prevalence of somatic complaints in players on their repeat concussions compared with their first concussion (27.5% versus 18.8%, P < 0.05). More than 90% of players were managed by rest, and 57.5% of those with second injuries returned to play within a day. Players with three or more concussions had signs, symptoms, and treatment similar to those with only a single injury. CONCLUSION:The most vulnerable players for repeat concussion in professional football are the ball return carrier on special teams and quarterbacks. Single and repeat concussions are managed conservatively with rest, and most players return quickly to play.

Concussion in Professional Football: Players Returning to the Same Game—Part 7

OBJECTIVE:A 6-year study was conducted to determine the signs, symptoms, and outcome of players who were concussed and either returned immediately or were rested and returned to the same game in the National Football League (NFL). METHODS:From 1996 to 2001, concussions were recorded by NFL teams by use of a special standardized reporting form filled out by team physicians. Signs and symptoms were grouped by general symptoms, somatic complaints, cranial nerve effects, cognition problems, memory problems, and unconsciousness. Action taken after concussion was recorded for 887 patients. RESULTS:There were 135 players (15.2%) who returned immediately and 304 (34.3%) who rested and returned to the same game after concussion. There were few differences by player position or team activity about the injury or action taken. However, the mean number of signs and symptoms progressively increased from those who returned immediately (1.52), rested and returned to play (2.07), were removed from play (3.51), or were hospitalized (6.55). Immediate recall problems (odds ratio [OR], 1.93; confidence interval [CI], 1.26–2.94), memory problems (OR, 1.52; CI, 1.06–2.19), and the number of signs and symptoms (OR, 1.39; CI, 1.25–1.55) were predictive of removal from play or hospitalization. There was no statistical association between return to play in the same game and a subsequent concussion or a more serious concussion involving 7+ days out. CONCLUSION:Players who are concussed and return to the same game have fewer initial signs and symptoms than those removed from play. Return to play does not involve a significant risk of a second injury either in the same game or during the season. The current decision-making of NFL team physicians seems appropriate for return to the game after a concussion, when the player has become asymptomatic and does not have memory or cognitive problems.

Chronic Traumatic Encephalopathy in a National Football League Player

To the Editor: We read with great interest the article on a new microvascular retractor (1). The authors describe a very useful selfretaining microvascular retractor for the retraction and repositioning of cerebral blood vessels. They state that this retractor, with a semicircular tip, remains stable on pulsating vessels during the procedure and grossly preserves the vessel diameter. In our department, we have been using a comparable instrument (Fig. C1). The diameters of the blades are 2, 4, and 6 mm, respectively. However, this “microvascular retractor” is hand-held and not self-retaining, as the one described by the authors. This instrument has been used mainly during microvascular decompression surgery for lifting, manipulating, and repositioning offending cerebral vessels. It can anchor the vessel and permit its manipulation during retraction in the vertical and horizontal planes. This handheld retractor is especially useful when dealing with larger or elongated vessels that may easily slip from the classic suction tips of microdissectors.