Sports-Related Concussion: Diagnosis & Management

Transcription

1 Sports-Related Concussion: Diagnosis & Management Kenneth Barnes MD, MSc., CAQSM Internal Medicine, Pediatrics & Sports Medicine Kernodle Clinic Orthopaedics & Sports Medicine Adjunct Faculty, Moses Cone Sports Medicine Fellowship Assistant Professor, Exercise Sports Science, Elon University Clinical Adjunct Faculty, UNC-CH School of Medicine

2 Disclosure Neither I, Kenneth P. Barnes, MD, nor any family member(s), have any relevant financial relationships to be discussed, directly or indirectly, referred to or illustrated with or without recognition within the presentation.

3 Concussion Videos M&feature=results_video&playnext=1&list=PL410E11C33BA94 A89

4 Background Sports-related concussion huge challenge in Sports Medicine Decisions: sidelines ice rink heat of the battle Pressure: coaches parents the player

5 Overview Concussion is more complex than previously thought Changes in normal brain physiology Can persist even after symptoms apparently clear Potential for lasting/permanent damage Previous management strategies are inadequate

6 Definition Definition A complex pathophysiological process affecting the brain, induced by traumatic biomechanical forces Characterized by a rapid onset of cognitive impairment Concussions are often difficult to detect since most do not lead to a loss of consciousness or have other immediately recognizable symptoms Wide range of clinical signs/symptoms highly variable presentation

7 Pathophysiology Linear/rotational forces of acceleration and deceleration on or within the brain Microscopic level: neuron depolarization ion regulation membrane channels axon integrity glucose metabolism cell membrane stability production of oxidative free radicals Rare to see skull fractures, cerebral edema, intracranial bleeds, and epidural/subdural hematomas

8 Concussions on Rise 9% of all high school sports injuries vs. 5.5% in 1997 Greater participation Athletes bigger, stronger, faster Greater awareness

9 Concussion Silent Epidemic million sports related concussions/yr Higher incidence or recognized more? Can we manage concussions better and facilitate a better outcome for our student-athletes? Significant advances over the past decade however, still a great deal we do not understand High risk sports: FB, M/W soccer, M/W basketball, softball, baseball, VB

10 Concussion

11 Female Overview Females cognitively impaired 1.7x more frequently than males Females had more adverse effects from concussion 50% of athletes did not report their injury (2005)!

12 Youth Coaches & Concussions McLeod et al., 2007: 42% thought that LOC was required for a concussion 32% did not think a Grade 1 concussion required removal from competition (no longer use a grading system) 26% would let a symptomatic athlete return to play (RTP)

13 Classifications Many Classifications over the years: Cantu (1986) Colorado Medical Society (1991) American Academy of Neurology (1997) International Consensus Statements (2001,2004, 2008)

14 Cantu Classification Guidelines, 1986 Grade 1: No loss of consciousness, Post-traumatic amnesia for fewer than 30 minutes Grade 2: Loss of consciousness for fewer than 5 minutes OR Post-traumatic amnesia for more than 30 minutes Grade 3: Loss of consciousness for more than 5 minutes OR Post-traumatic amnesia for more than 24 hours

15 Colorado Medical Society Guidelines, 1991 Grade 1: Grade 2: Grade 3: No loss of consciousness, No post-traumatic amnesia, Confusion No loss of consciousness, Post-traumatic amnesia, Confusion Loss of consciousness of any duration

16 American Academy of Neurology Guidelines, 1997 Grade 1: No loss of consciousness, Concussion symptoms for fewer than 15 minutes Grade 2: No loss of consciousness, Concussion symptoms for more than 15 minutes Grade 3: Loss of consciousness of any duration

17 International Consensus Statements on Concussion Historical Overview Vienna, 2001 Broad definition, individualized approach, stepwise RTP Prague, 2004 Stressed difference in younger patients, simple vs complex Zurich, 2008 Abandoned simple vs complex, No RTP same day if < 18 yo, Stressed predisposing factors (i.e. multiple concussions) Underscored deficits can persist long after symptoms resolve Stressed value of neuropsychological testing (ImPact) SCAT2, pocket SCAT2, BESS assessment

18 Current Standard of Classification of Concussion According to the Zurich Conference in 2008: Concussion grading scales should no longer be used Terms simple and complex no longer used Concussion now considered as a single entity that can be affected by various modifying factors BOTTOM LINE management is more conservative!!

19 Definition (Consensus Statement on Concussion in Sport: 3 rd International Conference on Concussion in Sport, Zurich, November 2008) Caused by direct blow to head, face, neck, or elsewhere on the body with an impulsive force to the head Results in rapid onset of short-lived neurological impairment that resolves spontaneously May result in neuropathological changes, but acute clinical symptoms reflect functional disturbance rather than structural injury Results in graded set of symptoms that may or may not involve loss of consciousness. Resolution of symptoms typically follows sequential course No abnormality is seen on standard neuroimaging

20 Historical Perspectives Concussion scales: > 25 published by 2001; None based on valid scientific evidence Canadian guidelines (2000) four R's: recognition, response, rehabilitation, return

21 1. Recognition perhaps the most challenging aspect of managing sport-related concussion is recognizing the injury, especially in athletes with no obvious signs that a concussion has actually occurred Exact pathophysiological changes to the brain following concussion are not fully understood All concussions mandate evaluation by a medical doctor

22 Diagnosing Concussion

23 Diagnosing Concussion No longer use grading scales Different scales, not always congruent Treatment was based on Grade Severity can only be determined over time

24 Diagnosing Concussion History Exam Sideline Office Radiology

25 Diagnosing Concussion History Witnessed injury Report of injury LOC IS NOT NECESSARY! Symptoms

26 Concussion Assessment Assessment of acute concussion is multifactorial Assess signs, symptoms, behavior, and abnormal brain function Test memory What team are we playing? Who scored last? Test cognitive functioning Word recall (cat, pen) Digit recall (say backwards) Months in order (recall months in backward order) Neurological exam is paramount Speech, eye motion, pupils, pronator drift, balance testing Presence of one or more of these factors indicate high probability of concussion and should necessitate removal from field Sport Concussion Assessment Tool (SCAT) Quick standardized tool for concussion assessment

27 Sideline evaluation (1.) ABC s (2.) Exclude cervical spine injury (3.) Evaluate concussion, use standardized tools (i.e. SCAT2) if available (4.) Do not leave the player alone Serial monitoring for initial few hours following injury to observe for deterioration (5.) Player should not be allowed to return to field on day of injury

28 ED/Clinic Setting Do a complete H+P Do a comprehensive neurological exam Monitor for worsening signs/symptoms Obtain additional info from other sources (parents, coaches, trainers, etc.) Emergent neuroimaging only if there is concern for severe brain injury or abnormality -- Usually NOT necessary!!

29 Neuroimaging CT MRI Study of choice Greater accessibility Good for intracranial hemorrhage, contusion, or herniation More sensitive and specific than CT in identifying small cerebral contusions, edema, and small nonhemorrhagic lesions Prohibited by: cost, availability, claustrophobia, metal hardware in body Other imaging studies Functional MRI (f MRI) Diffusion tensor imaging (DTI) Positron Emission Tomography (PET) Single Photon Emission Computerized Tomography (SPECT) Near Infrared Spectroscopy (NIRS)

30 Diagnosing Concussion Signs/Symptoms Visual changes Balance problems Dizziness Confusion Memory loss Irritability / changes in emotion Difficulty concentrating Difficulty with sleep (sleep or wake) Headache Light sensitivity

31 2. Response Suspected concussion: Immediate removal Return while symptomatic may greatly increase the risk of more severe post-concussive symptoms and a more prolonged post-concussive course Second Impact Syndrome feared but rare Concussion = Functional brain injury only image if suspect a structural injury Neuropsych assessment: demonstrated to be an extremely valuable tool

32 Concussion Treatment

33 Concussion Treatment Plenty of rest and fluids Let them sleep! No 2 hr rule Avoid aspirin NSAIDs

34 Concussion Management Patience is key! Physical AND cognitive rest until symptoms resolve. When symptomatic, restrict/prohibit physical activity and activities involving attention and concentration. Emphasize delay in recovery if athlete resumes these activities too soon. Do not overlook depression, anxiety, or mood disturbances. Recovery should be based on the individual, NOT tables or guidelines. Several factors will modify concussion management (Table 1).

35 Concussion Modifiers TABLE 1. Concussion Modifiers Factors: Symptoms Signs Sequelae Temporal Threshold Modifier: Number Duration (>10 days) Severity Prolonged LOC (>1 min), amnesia Concussive convulsions Frequency - repeated concussions over time Timing - injuries close together in time Recency - recent concussion or TBI Repeated concussions occurring with progressively less impact force or slower recovery after each successive concussion

36 Concussion Modifiers (Table 1, Continued) Factors: Age Co- and Pre-morbidities Medication Behaviour Sport Modifier: Child and adolescent (< 18 years old) Migraine, depression or other mental health disorders, attention deficit hyperactivity disorder (ADHD), learning disabilities (LD), sleep disorders Psychoactive drugs, anticoagulants Dangerous style of play High-risk activity, contact and collision sport, high sporting level

37 Pharmacology Helps to manage symptoms including anxiety, depression, insomnia, and headache Acute anxiety BZD s Depression SSRI s Insomnia BZD s, TCA s Cognitive slowing/fatigue psychostimulants (i.e. Provigil), dopaminergic agents (i.e. Levodopa) Mania/Psychosis typical/atypical antipsychotics (i.e. Risperdal) Prior to returning to play, athlete needs to be symptom-free and off these medications (except for antidepressants) Initiation of these medications need close monitoring

38 Neuropsychological Testing Use is heavily market driven Provides a way to assess information relating to neurological deficits suffered post-concussion when compared to baseline neurological function Adjunct to clinical decision making process (CAN NOT determine RTP) No reason to test while the athlete is symptomatic Sometimes difficult to draw accurate conclusions without a baseline test

39 Neuropsychological Testing Expense ($750-$4,000) and time factor (30 min to 3 hours) limits widespread use Recommended that trained neuropsychologists are needed to assess findings Examples: Immediate Post Concussion Assessment and Cognitive Testing (ImPACT ) Headminder

40 Neuropsychological Testing General rule of thumb: For as long as it takes for symptoms to clear, it is the same length of time before the athlete is ready to RTP Once symptoms clear... Repeat computer test (if have baseline) Good approach: Retest only asymptomatic patients Avoids problems with practice effects and false negatives

41 3. Rehabilitation Traditionally: Orthopedic Model 1. Phase 1: healing phase, rest, modalities 2. Phase 2: return to fxn, ROM, strength, stability, proprioception, flexibility 3. Phase 3: return to sport, graduated increase in sport-specific activity

42 3. Rehabilitation Concussion Model REST!!! Physical and Cognitive!!! Symptoms aggravated by exertion (physical & cognitive) differs from orthopedic model absolute rest a must fitness activity, aerobic activity, exertional ADL's Concentration, memorization and learning can aggravate post-concussive symptoms Rest MUST involve cognitive rest Most difficult phase athlete used to working through pain (needs extensive education and support)

43 4. Return

44 Cantu Concussion Guidelines, Return to Play Management based on first concussion: Grade 1: Athlete may return to play if asymptomatic for one week (if athlete is totally asymptomatic, return to play on same day may be considered). Grade 2: Athlete may return to play if asymptomatic for one week. Grade 3: Athlete may not return to play for at least one month; athlete may then return to play if asymptomatic for one week.

45 Colorado Medical Society Guidelines, Return to Play Management based on first concussion: Grade 1: Athlete may return to play if asymptomatic for 20 minutes. Grade 2: Grade 3: Athlete may return to play if asymptomatic for one week. Athlete should be transported to a hospital emergency department; athlete may return to play one month after injury if asymptomatic for two weeks.

46 American Academy of Neurology Guidelines, Return to Play Management based on first concussion: Grade 1: Athlete may return to play if asymptomatic for 15 minutes. Grade 2: Athlete may return to play if asymptomatic for one week. Grade 3: Athlete should be transported to a hospital emergency department; if athlete had brief loss of consciousness (i.e., seconds), may return to play when asymptomatic for one week; if athlete had prolonged loss of consciousness (i.e., minutes), may return to play when asymptomatic for two weeks.

47 International Consensus Statements on Concussion Graduated Return to Play Protocol Step-wise process Each step = 24 hours Progress to next step if asymptomatic for at least 24 hours at that current level If symptomatic, rest for 24 hours, then drop athlete down to previous asymptomatic step and try to progress again

48 Graduated Return to Play Protocol TABLE 2. Graduated Return to Play Protocol Rehabilitation Stage Functional Exercise at Each Stage of Rehabilitation Objective of Each Stage 1. No activity Complete physical and cognitive rest Recovery 2. Light aerobic exercise Walking, swimming or stationary cycling keeping Increase HR intensity, <70% MPHR; no resistance training 3. Sport-specific exercise Skating drills in ice hockey, running drills in soccer; Add movement no head impact activities 4. Non-contact training drills Progression to more complex training drills, eg, Exercise, coordination, and passing drills in football and ice hockey; may start sport specific activity progressive resistance training 5. Full contact practice Following medical clearance, participate in normal Restore confidence and assess training activities functional skills by coaching staff 6. Return to play Normal game play

49 Ongoing research Pediatric population Genetic/biomarker testing Second Impact Syndrome Male vs. female athlete Protective equipment (i.e. helmets, mouthgards)

50 Pediatric Athlete Not a little adult! Growth and development make concussion assessment and management very difficult Less neck and shoulder musculature less capable of transferring kinetic energy at the head throughout the body Neurological development at risk Ability to focus Sustain attention Memory recall Rapid information processing

51 Pediatric Athlete No set timetable for recovery Need to be conservative on return to play protocol Consider extending out time of one or more steps Emphasize cognitive rest and longer recovery period Studies still limited in terms of the pediatric population

52 Genetics Current investigations ongoing to evaluate the association of genotypes, alleles, and genetic biomarkers to concussions S100B predicts long-term disability from a head injury Apo E4 risk factor for Alzheimer s G-219T polymorphism of ApoE promoter increased risk for Alzheimer s and unfavorable post-concussive outcomes Tau mutation on Chromosome 17 frontotemporal dementia

53 Repeated Concussive Injury

54 Repeated Concussive Injury Concern for Second Impact Syndrome (SIS) Athlete sustains head injury while still symptomatic from a previous head injury Second head injury leads to metabolic disruption and loss of autoregulation of cerebral blood supply Results in cerebral vascular engorgement, cerebral edema/swelling, increased intracranial pressure, cerebral/brainstem herniation, and ultimately, coma and death Rare, but is of great concern in pediatric population due to immaturity of the brain Contact sports (i.e. football, hockey) increase risk of SIS

55 Repeated Concussive Injury The Zack Lystedt Law: year-old Zachery Lystedt, from Maple Valley, WA, suffered a life-threatening brain injury after he returned to play football following a hard hit earlier in the game May Gov. Christine Gregoire signed the nation's toughest youth athlete return-to-play law Washington was the 1 st State to pass concussion legislation

56 The Zackary Lystedt Law

57 Gfeller-Waller Awareness Act Matthew Gfeller died in August 2008: he sustained a head injury during a high school football game in Winston-Salem he played for R.J. Reynolds High School Jaquan Waller died in September 2008: he sustained a head injury during a high school football game in Greenville He played for J.H. Rose High School Waller suffered from Second Impact Syndrome Gfeller died from a single concussion

58 Gfeller-Waller Awareness Act NC was the 16 th State to pass concussion legislation

59 Gfeller-Waller Awareness Act Signed into law on June 16, 2011 by Governor Purdue Purpose: to protect the safety of student-athletes in NC 3 major areas of focus: education emergency action post-concussion protocol implementation, and clearance/return to play or practice following concussion

60 Post-Concussion Protocol If a student-athlete exhibits signs and symptoms consistent with a concussion (even if not formally diagnosed), the studentathlete is to be removed from play and is not allowed to return to play (game, practice, or conditioning) on that day - "When in doubt, sit them out!! Student-athletes are encouraged to report their own symptoms, or to report if peers may have concussion symptoms Coaches, parents, volunteers, first responders, school nurse, licensed athletic trainers (if available), are responsible for removing a student-athlete from play if they suspect a concussion

61 Post-Concussion Protocol Following the injury, the student-athlete should be evaluated by a qualified medical professional with training in concussion management It is strongly recommended that each institution seek qualified medical professionals in the surrounding community to serve as resources in the area of concussion management In order for a student- athlete to return to play without restriction, he/she must have written clearance from appropriate medical personnel The form that should be used for this written clearance is posted on this website: ntid=8440&type=5&atomid=11952

62 Take Home Points Concussion present a complex problem No simple concussions and no two concussions are alike Treat each athlete or patient as an individual Education/Awareness for everyone Baseline testing is ideal (SCAT2, SAC, BESS) Be thorough in the initial evaluation and subsequent follow-up

63 Take Home Points Neuroimaging valid when suspicious for serious brain injury, otherwise no imaging needed Management is STRICT REST physical and cognitive Never RTP if symptomatic Be conservative on return to play Be even more conservative with pediatric athletes NO ONE returns to play same day of a suspected concussion

64 Final Thoughts. within the context of concussion, we are left to wonder why an investment of 4 months to rehabilitate a high ankle sprain is considered acceptable, whereas 4 months for brain rehabilitation is considered unacceptable

65 Questions?

66 Thank You

67 References 1. McCrory, P. and Meeuwisse, W. Consensus Statement on Concussion in Sport: the 3rd International Conference on Concussion in Sport held in Zurich, November Br. J. Sports Med (Suppl I): 43; i76-i McCrory, P. and Johnston, K. Summary and Agreement Statement of the 2nd International Conference on Concussion in Sport, Prague Clin. J. Sports Med: Vol 15, Number 2, March 2005, pp Aubry, M. and Cantu, R. Summary and Agreement Statement of the First International Conference in Sport, Vienna The Physician and Sports Medicine: Vol 30, Number 3, February Herring, S. and Bergfield, J. Concussion (Mild Traumatic Brain Injury) and the Team Physician: A Consensus Statement. Official Journal of the American College of Sports Medicine, Medicine & Science in Sports & Exercise: November 2005, pp Anderson, T. and Heitger, M. Concussion and Mild Head Injury. Practical Neurology 2006: Vol 6, pp Akhavan, A. and Flores, C. How should we follow athletes after a concussion?. The Journal of Family Practice: October 2005, Vol 54, Number Goldberg, L. and Dimeff, R. Sideline Management of Sports-related Concussions. Sports Medicine and Arthroscopy Review: Vol 14 (4), December 2006, pp Kushner, D. Concussion in Sports: Minimizing the Risk for Complications. American Family Physician: Vol 64, Number 6, pp Tator, C. Concussions are Brain Injuries and Should be Taken Seriously. Can. J. Neurol. Sci. 2009: Vol 36, pp Mayers, L. Return-to-Play Criteria After Athletic Concussion. Arch. Neurology 2008: Vol 65, Number 9, pp Covassin, T. and Elbin, R. Current Sport-Related Concussion Teaching and Clinical Practices of Sports Medicine Professionals. Journal of Athletic Training: Vol 44, Number 4, August 2009, pp Davis, G.A. and Iverson, G.L. Contributions of Neuroimaging, Balance Testing, Electrophysiology, and Blood Markers to the Assessment of Sport-related Concussion. Br. J. Sports Med 2009: Vol 43 (Suppl I), i36-i45.

68 References 13. Johnston, K. and Ptito, A. New Frontiers in Diagnostic Imaging in Concussive Head Injury. Clin. J. Sport Med: Vol 11, Number 3, 2001, pp Schrader, H. and Mickeviciene, D. Magnetic resonance imaging after most common form of concussion. BMC Medical Imaging 2009: Vol 9, Number 11, pp Iverson, G. Outcome from mild traumatic brain injury. Current Opinion in Psychiatry 2005: Vol 18, pp Paoli de Almeida Lima, D. and Simao Filho, C. Quality of life and neuropsychological changes in mild head trauma. Late analysis and correlation with S100B protein and cranial CT scan performed at hospital admission. Injury, Int. J. Care Injured 2008: Vol 39, pp Kristman, V. and Tator, C. Does the Apolipoprotein E4 Allele Predispose Varsity Athletes to Concussion? A Prospective Cohort Study. Clin. J. Sport Med: Vol 18, Number 4, July 2008, pp Roland Terrell, T. and Bostick, R. APOE, APOE Promoter, and Tau Genotypes and Risk for Concussion in College Athletes. Clin. J. Sport Med: Vol 18, Number 1, January 2008, pp Hutchinson, M. and Mainwaring, L. Differential Emotional Responses of Varsity Athletes to Concussion and Musculoskeletal Injuries. Clin. J. Sport Med: Vol 19, Number 1, January 2009, pp Bruce, J. and Echemendia, R. History of Multiple Self-reported Concussions is Not Associated with Reduced Cognitive Abilities. Neurosurgery: Vol 64, Number 1, January 2009, pp The ImPACT Test. Sideline ImPACT Schatz, P. and Pardini, J. Sensitivity and specificity of the ImPACT Test Battery for concussion in athletes. Archives of Clin. Neuropsychology: Vol 21, Issue 1, January 2006, pp Cernich, A. and Reeves, D. Automated Neuropsychological Assessment Metrics Sports Medicine Battery. Archives of Clin. Neuropsychology: 22S (2007) S Broglio, S and Macciochi, S. Sensitivity of the Concussion Assessment Battery. Neurosurgery: Vol 60, Number 6, June 2007, pp

69 References 25. McCrea, M. and Barr, W. Standard regression-based methods for measuring recovery after sport-related concussion. Journal of the International Neuropsychological Society (2005): Vol 11, pp Shuttleworth-Edwards, A. Central or peripheral? A positional stance in reaction to the Prague statement on the role of neuropsychological assessment in sports concussion management. Archives of Clin. Neuropsychology 2008: Vol 23, pp Guskiewicz, K. Postural Stability Assessment Following Concussion: One Piece of the Puzzle. Clin. J. Sport Med 2001: Vol 11, pp Solomon, G. and Haase, R. Biopsychosocial characterisitics and neurocognitive test performance in National Football League players: An initial assessment. Arch. of Clin. Neuropsych 2008: Vol 23, pp Boutin, D. and Lassonde, M. Neuropsychological assessment prior to and following sports-related concussion during childhood: A case study. Neurocase 2008: Vol 14, Number 3, pp Scolaro Moser, R. and Iverson, G. Neuropsychological evaluation in the diagnosis and management of sports-related concussion. Arch of Clin. Neuropsych: Vol 22, Issue 8, November 2007, pp Maroon, J. and Lovell, M. Cerebral Concussion in Athletes: Evaluation and Neuropsychological Testing. Neurosurgery: Vol 47, Number 3, September 2000, pp Grindel, S. and Lovell, M. The Assessment of Sport-Related Concussion: The Evidence Behind Neuropsychological Testing and Management. Clin. J. of Sport Med 2001: Vol 11, pp Broglio, S. and Macciochi, S. Neurocognitive Performance of Concussed Athletes When Symptoms Free. Journal of Athletic Training 2007: Vol 42, Number 4, pp Echemendia, R. and Herring, S. Who should conduct and interpret the neuropsychological assessment in sportsrelated concussion? Br. J. Sports Med 2009: 43 (Suppl I) pp i32-i Putukian, M. and Aubry, M. Return to play after sports concussion in elite and non-elite athletes. Br. J. Sports Med 2009: 43 (Suppl I) pp i28-i Cohen, J. and Giola, G. Sports-related concussion in pediatrics. Current Opinion in Pediatrics 2009: Vol 21, pp De Beaumont, L. and Theoret, H. Brain function decline in healthy retired athletes who sustained their last sports concussion in early adulthood. Brain 2009: Vol 132, pp

70 References 38. Covassin, T. and Swanik, C. B. Sex differences in baseline neuropsychological function and concussion symptoms of collegiate athletes. Br. J. Sports Med 2006: Vol 40, pp Covassin, T. and Schatz, P. Sex differences in neuropsychological function and post-concussion symptoms of concussed collegiate athletes. Neurosurgery 2007: Vol 61, pp Standaert, C. and Herring, S. Expert Opinion and Controversies in Sports and Musculoskeletal Medicine: Concussion in the Young Athlete. Arch Phys Med Rehabil: Vol 88, pp , August Scolaro Moser, R. and Schatz, P. Enduring effects of concussion in youth athletes. Arch of Clin. Neuropsych 2001: Vol 17, Issue 1, January 2002, pp Field, M. and Collins, M. Does age play a role in recovery from sports-related concussion? A comparison of high school and collegiate athletes. Journal of Pediatrics: Vol 42, Issue 5, May Kirkwood, M. and Owen Yeates, K. Pediatric Sport-Related Concussion: A Review of the Clinical Management of an Oft-Neglected Population. Pediatrics: Vol 117, Number 4, April 2006, pp Ashare, A. Returning to play after concussion. Acta Paediatrica 2009: Vol 98, pp Purcell, L. What are the most appropriate return-to-play guidelines for concussed child athletes? Br. J. Sports Med 2009: Vol 43 (Suppl I) pp i51-i Gessel, L. and Fields, S. Concussions Among United States High School and Collegiate Athletes. Journal of Athletic Training: Vol 42, Number 4, December 2007, pp Giola, G. A. and Schneider, J. C. Which symptom assessments and approaches are uniquely appropriate for paediatric concussion? Br. J. Sports Med 2009: Vol 43 (Suppl I), pp i13-i Dick, R. W. Is there a gender difference in concussion incidence and outcomes? Br. J. Sports Med 2009: Vol 43 (Suppl I), pp i46-i McCrory, P. Does Second Impact Syndrome Exist? Clin. J. Sport Med 2001: Vol 11, Number 3, pp Guskiewicz, K. and McCrea, M. Cumulative Effects Associated With Recurrent Concussion in Collegiate Football Players. JAMA: Vol 290, Number 19, November 19, 2003, pp

71 References 51. McCrea, M. and Guskiewicz, K. Acute Effects and Recovery Time Following Concussion in Collegiate Football Players. JAMA: Vol 290, Number 19, November 19, 2003, pp Covassin, T. and Stearne, D. Concussion History and Postconcussion Neurocognitive Performance and Symptoms in Collegiate Athletes. Journal of Athletic Training 2008: Vol 43, Number 2, pp Miller, G. A Late Hit for Pro Football Players. Science: Vol 325, August 7, 2009, pp Singh, G. D. and Maher, G. Customized mandibular orthotics in the prevention of concussion/mild traumatic brain injury in football players: a preliminary study. Dental Traumatology: Vol 25, Issue 5, July 9, 2009, pp Levy, M. and Ozgur, B. Birth and Evolution of the Football Helmet. Neurosurgery: Vol 55, Number 3, September 2004, pp Levy, M. and Ozgur, B. Analysis and Evolution of Head Injury in Football. Neurosurgery: Vol 55, Number 3, September 2004, pp Benson, B. W. and Hamilton, G. M. Is protective equipment useful in preventing concussion? A systematic review of the literature. Brit. J. Sport Med 2009: Vol 43 (Suppl I), pp i56-i67.