Concussions (Mild Traumatic Brain Injury) - Knee & Sports

Summary
- Concussions are a subset of mild traumatic brain injury (mTBI) characterized by acute transient impairment of neurologic function secondary to an impulsive force transmitted to the head.
- Diagnosis is made by careful neurological evaluation of an athlete following head trauma with a focus on cognitive function.
- Treatment is immediate removal from play followed by cognitive and physical rest for 24-48 hours, and subsequent completion of a graduated return to play protocol.

Epidemiology
- Incidence
  - 1.6-3.8 million sports-related concussions per year
    
    increasing over the past decade, though possibly due to increased awareness
    
    substantial rise in youth athletes is concerning
  - 5-9% of all sports injuries
- Demographics
  - traumatic brain injury (TBI) is the leading cause of sport-related death
  - American football associated with the majority of concussions
  - occur in competition more often than practice

Etiology
- Pathophysiology
  - direct blow to the head, face, neck or elsewhere with force transmitted to the head
  - complex neurometabolic cascade resulting in the typical signs and symptoms of a concussion
    
    abnormal neuronal ionic flux -- headache, photophobia, phonophobia
    
    altered release of neurotransmitters (glutamate) -- impaired cognition, amnesia, slowed reaction time
    
    energy depletion, in an effort to correct the above underlying biochemical imbalances -- vulnerable to second injury (second-hit phenomenon)
  - may or may not experience loss of consciousness
    
    not required for diagnosis of concussion
- Risk factors
  - sports with player-to-player contact
    
    football, wrestling, soccer, basketball at highest risk
  - prior concussion
    
    2-8x higher risk of sustaining another concussion
  - female
  - age < 18 years
  - mood disorders, learning disorders, history of migraines
    
    may complicate diagnosis and recovery
- Guidelines
  - International Conference on Concussion in Sport
    
    meeting held every 4 years
    
    focuses on the prevention, diagnosis and management of sports-related concussion
    
    generates a consensus statement summarizing the updated practice guidelines
    
    consensus statement created at the first meeting in 2001
    
    grading system for concussions removed in 2004
    
    all classification systems removed in 2008
    
    newer assessment tools and timing of return to play was the primary focus of the most recent meeting

Presentation
- Symptoms
  - somatic symptoms
    
    headache
    
    most common symptom
    
    present in 70% of concussed athletes
    
    types
    
    myofascial tension headache -- pain localized to posterior neck at base of skull
    
    post-traumatic headache -- pressure localized to forehead and/or top of head
    
    dizziness
    
    balance problems
    
    nausea and/or vomiting
    
    vision changes
    
    sensitivity to light (photophobia) or sound (phonophobia)
  - cognitive symptoms
    
    feeling "in a fog" or slowed down
    
    difficulty concentrating
    
    forgetful
  - emotional symptoms
    
    lability
    
    irritability
    
    sadness
  - sleep disturbance
    
    change in amount of sleep (more or less)
    
    difficulty falling asleep, insomnia
    
    drowsiness
- Signs
  - many sports have established "mandatory signs of concussion"
    
    presence of these visible signs dictates further evaluation and often removal from play
    
    note, the specific signs and subsequent recommended action differs between sports
  - loss of consciousness
    
    occurs in only ~10% of cases
  - lying motionless > 5 seconds
  - slow to get up
  - confusion or disorientation
  - clutching the head
  - amnesia
  - vacant look
  - motor incoordination
  - ataxia

Evaluation
- Sideline evaluation
  - primary survey
    
    airway, breathing, circulation
    
    assess for spinal cord injury
    
    cervical collar and back board immobilization if needed
    
    in an altered patient, assume cervical spine injury until proven otherwise
    
    indications for transport to ER for advancing imaging
    
    deteriorating mental status
    
    increasingly restless, agitated or combative
    
    severe or worsening headache
    
    focal neurologic findings
    
    unequal pupils
    
    abnormal extraocular eye movements
    
    motor and/or sensory deficit
    
    neck pain or tenderness concerning for cervical spine injury
    
    do not leave player alone after injury
  - secondary survey -- evaluate cognitive function
    
    any athlete with symptoms or signs of a concussion should be removed from the playing field and undergo immediate cognitive evaluation by a licensed healthcare provider
    
    if no healthcare provider is avaliable, the athlete should be removed from play entirely and urgently referred to a physician
    
    sideline assessment tool that tests attention and memory
    
    SCAT5 is the most commonly used
  - Sports Concussion Assessment Tool 5 (SCAT5)
    
    standardized neuropsychological test for evaluating concussions in athletes aged 13 years or older
    
    child SCAT5 can be used for younger athletes
    
    composed of two parts
    
    immediate on-field assessment
    
    office or off-field assessment
    
    immediate on-field assessment
    
    red flags
    
    observable signs
    
    witnessed or on video review
    
    Maddocks questions -- memory assessment
    
    Glasgow Coma Scale (GCS)
    
    cervical spine assessment
    
    off-field assessment
    
    should be done in a private, distraction-free area
    
    Standard Assessment of Concussion (SAC) test
    
    Balance Error Scoring System (BESS) test

Imaging
- Advancing imaging
  - usually unnecessary
  - need for imaging is determined by the evaluating physician
  - indications
    
    acute head trauma with
    
    deteriorating mental status
    
    increasingly combative, aggressive, restless
    
    focal neurologic deficit
    
    neck pain concerning for cervical spine injury
    
    history of subacute/chronic head trauma with persistent symptoms
- Computerized tomography (CT) head
  - most commonly used in the acute setting
  - findings
    
    normal in vast majority
    
    can identify fractures, intracranial hemorrhage, contusion, mass effect and herniation
- Magnetic resonance imaging (MRI) brain
  - superior visualization of brain structures
  - diffusion-weighted imaging (DWI) most sensitive to shear injury
  - findings
    
    standard MRI normal in vast majority
    
    concussion is most often a functional rather than structural pathology
    
    functional MRI can show increased cerebrovascular reactivity in the acute post-concussive period

Neuropsychological Assessment Tools
- Standard Assessment of Concussion (SAC) test
  - evaluates
    
    orientation (ex. What month is it?)
    
    memory, immediate and delayed (ex. repeating 5 words over 3 trials and 1 trial at the conclusion of assessment
    
    concentration (ex. repeating string of 5 numbers backwards)
- Immediate Post-concussion Assessment and Cognitive Testing battery (ImPACT)
  - a computer-based test that assesses verbal and visual memory, processing speed, reaction time, impulse control and presence of concussive symptoms
  - comparison is made to baseline scores or historical controls
  - useful tool in guiding treatment and return to play decisions
- Balance Error Scoring System (BESS)
  - tests balance and postural stability by having the athlete perform 3 stances for 10 seconds each
    
    bipedal stance
    
    unipedal stance
    
    tandem stance
- Sensory Organization Test (SOT)
  - assesses integrity of the entire balance system by testing the vestibular, visual and somatosensory systems, which are responsible for postural stability and maintenance of balance
- King-Devick (K-D) Test
  - examines saccadic eye movements, language and concentration by having the athlete rapidly read numbers off a card from left to right for 3 successive tests
- Sports Concussion Assessment Tool 5 (SCAT5)
  - reviewed under Sideline evaluation

                        Treatment
                    
                        Nonoperative
                    
                        immediate removal from play, same day return to play is NOT indicated   
                    
                        indications
                    
                        athletes of any age with signs/symptoms concerning for concussion (see above)
                    
                        if concerned at all, remove athlete from play!
                    
                        athletes with head trauma and no medical provider experienced in concussion evaluation present
                    
                        head trauma with history of concussion
                    
                        loss of consciousness
                    
                        amnesia
                    
                        positive exertional stress test
                    
                        symptoms lasting > 15 minutes
                    
                        cognitive and physical rest x24-48H, graduated return to play protocol    
                    
                        indications
                    
                        acute concussion
                    
                        technique
                    
                        same day return to play is contraindicated in patients diagnosed with a concussion
                    
                        graduated return to play protocol highlighted in table below
                    
                        each step should take 24 hours, so an athlete should take one week to proceed through the full protocol and return to play
                    
                                            Graduated Return to Play Protocol
                                        
                                            Stage
                                        
                                            Activity 
                                        
                                            Goal 
                                        
                                            1. Symptom-limited activity
                                        
                                            Daily activities that do not provoke symptoms

                                            Gradual reintroduction of work/school activities
                                        
                                            2. Light aerobic exercise
                                        
                                            Walking, swimming, or stationary cycling to maintain HR at <70% of maximum. No resistance training.
                                        
                                            Increase heart rate
                                        
                                            3. Sport-specific exercise
                                        
                                            Running or skating drills. No head impact activities.

                                            Add movement
                                        
                                            4. Non-contact training drills
                                        
                                            More complex training drills (i.e. passing drills). May start progressive resistance/strength training.
                                        
                                            Exercise, coordination, and improved cognition
                                        
                                            5. Full contact practice
                                        
                                            Normal training activities.

                                            Restore confidence, assess functional skills
                                        
                                            6. Return to play
                                        
                                            Normal game play

Prevention
- Protective equipment
  - head gear and helmets reduce impact forces to the brain
  - helmet use is associated with decreased rates of head and neck injuries in certain sports
    
    youth hockey, alpine, equestrian, cycling and motor sports
  - risk compensation
    
    use of protective equipment may paradoxically increase injury rates by enabling more dangerous playing techniques
- Rules changes
  - beneficial when a clear cut mechanism is implicated in a particular sport
    
    upper limb-to-head contact banned in American football
    
    accounted for ~50% of concussions
    
    strict enforcement of red cards for high elbows in professional soccer
- Community education
  - players, coaches, athletic trainers, referees and the general public
  - focus on safe play, identification of concussion and appropriate graduated return to play
    
    minimizing premature return to play decreases risk of long-term complications
- Preparticipation concussion evaluation
  - number of previous concussions, type and severity of symptoms, length of recovery
  - mechanism of injury
    
    low-impact injury but with disproportionately high symptom severity can indicate an athlete who is particularly vulnerable to injury
  - great opportunity for education and modification of high-risk behavior
- Future research
  - energy-absorbing artifical turf fields
  - genetic tests -- apolipoprotein E
  - specific playing technique -- limited contact football, different tackling techniques

Complications
- Second impact syndrome
  - second head trauma before symptoms of a concussion have resolved
  - catastrophic cerebral edema resulting from loss of autoregulation of the brain blood supply
  - high rate of death and disability
    
    mortality rate ~50%
  - associated with male gender, young age and American football
- Postconcussion syndrome
  - persistent symptoms of a concussion (i.e. headache, confusion)
    
    > 10-14 days in adults
    
    > 4 weeks in children
  - return to play is contraindicated
  - should undergo formal neuropsychiatric evaluation
  - use of pharmacotherapy is controversial
- Intracranial hemorrhage
  - subdrual hematoma most common
  - epidural hematoma
    
    commonly have a lucid period before neurologic decline
    
    neurosurgical decompression and seizure prophylaxis indicated
- Chronic traumatic encephalopathy (CTE)
  - progressive neurologic deterioration resulting from repetitive brain trauma
  - symptoms
    
    behavior changes -- loss of impulse control, aggression, irritability
    
    mood changes -- depression, apathy, suicidal ideation
    
    cognitive impairment -- difficulty with executive functions (i.e. carrying out tasks), memory loss, dementia
  - diagnosis
    
    postmortem neuropathologic examination of the brain
    
    cerebral atrophy
    
    enlarged ventricles
    
    diffuse senile plaques

Graduated Return to Play Protocol
Stage	Activity	Goal
1. Symptom-limited activity	Daily activities that do not provoke symptoms	Gradual reintroduction of work/school activities
2. Light aerobic exercise	Walking, swimming, or stationary cycling to maintain HR at <70% of maximum. No resistance training.	Increase heart rate
3. Sport-specific exercise	Running or skating drills. No head impact activities.	Add movement
4. Non-contact training drills	More complex training drills (i.e. passing drills). May start progressive resistance/strength training.	Exercise, coordination, and improved cognition
5. Full contact practice	Normal training activities.	Restore confidence, assess functional skills
6. Return to play	Normal game play