Concussions (Mild Traumatic Brain Injury) - Knee & Sports

Introduction

Definition
- 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
Epidemiology
- 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
- 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
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