Concussion / Mild Traumatic Brain Injury
Trauma-induced transient brain dysfunction without imaging abnormality.
Also known as: concussion, mild TBI, mTBI, post-concussive syndrome, PCS
Overview
A complex pathophysiologic process affecting the brain induced by traumatic biomechanical forces, producing transient impairment of neurologic function. Typically GCS 13-15, loss of consciousness <30 minutes (often none), and post-traumatic amnesia <24 hours, with normal structural neuroimaging.
Epidemiology
~3-4 million sports-related concussions per year in the US; many more from falls, MVCs, military blast injuries, and assaults. Up to 40% of patients have symptoms beyond 1 month (persistent post-concussive symptoms).
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Risk factors
- Contact sports: football, hockey, soccer, lacrosse, rugby, boxing, MMA
- Prior concussion (especially within the last year — risk of second impact syndrome)
- Younger age (children and adolescents recover more slowly than adults)
- Female sex (higher reported incidence in same sports)
- Pre-existing migraine, ADHD, learning disability, anxiety/depression
- Falls in elderly, MVCs at any age
- Military service (blast exposure)
Pathophysiology
Rotational and linear acceleration forces produce shear stress on axons and a transient neurometabolic cascade: indiscriminate neurotransmitter release, ionic shifts (potassium efflux, calcium influx), hypermetabolic glucose use to restore ionic gradients, and reduced cerebral blood flow. The mismatch between energy demand and supply leaves the brain vulnerable to a second hit during this metabolic crisis (second impact syndrome).
Clinical presentation
Symptoms
- Headache (most common)
- Confusion, feeling 'in a fog'
- Dizziness, balance problems
- Nausea/vomiting
- Photophobia, phonophobia
- Difficulty concentrating, slowed thinking
- Memory problems (especially retrograde and anterograde amnesia around the event)
- Sleep disturbance, fatigue, irritability, emotional lability
Signs / physical exam
- Often normal neurologic exam after the acute phase
- Abnormalities on sideline assessment tools (SCAT-6: symptom checklist, cognitive testing, balance — modified BESS)
- Vestibular/ocular motor screening (VOMS) abnormalities — smooth pursuit, saccades, convergence, VOR
- Possible mild postural instability
Classic findings
Transient confusion, amnesia for the event, and normal neuroimaging following biomechanical force to the head.
Differential diagnosis
- Intracranial hemorrhage (SDH, EDH, contusion) — Persistent or worsening symptoms, focal deficit, GCS deterioration — CT mandatory if Canadian CT Head Rule positive
- Cervical strain / whiplash — Neck pain, decreased ROM; can coexist with concussion; image cervical spine
- Vertebrobasilar TIA / dissection — Vertigo, diplopia, dysarthria after trauma; CTA of neck vessels
- Vestibular concussion (peripheral) — Vertigo, nausea, abnormal vestibular ocular reflex; positional testing
- Migraine triggered by trauma — Throbbing, photophobia, aura; responds to migraine therapy
- Post-traumatic seizure — Witnessed convulsion, tongue bite, postictal state
- Functional / psychogenic — Inconsistent exam, secondary gain, normal imaging — diagnosis of exclusion
Diagnostic workup
Diagnostic criteria
Clinical: traumatic mechanism + altered mental status / symptoms / amnesia + normal structural imaging. No single laboratory or imaging test is required.
Labs
- Generally not indicated
- Consider glucose, blood alcohol, drug screen if altered mental status
- GFAP/UCH-L1 blood biomarker (FDA-cleared) can help rule out CT-positive injury in select adults
Imaging
- Non-contrast head CT if any Canadian CT Head Rule criteria positive: GCS <15 at 2 h, suspected open/depressed skull fracture, signs of basilar fracture, vomiting ≥2 episodes, age ≥65, amnesia >30 min, dangerous mechanism
- MRI not routinely needed; consider if persistent symptoms beyond expected recovery or focal findings
- Cervical spine imaging per NEXUS or Canadian C-spine Rules
Diagnostic algorithm
| Step | Activity | Goal |
|---|---|---|
| 1 | Symptom-limited activity (daily activities, light cognitive tasks) | Tolerate cognitive/physical activity without symptom exacerbation |
| 2 | Light aerobic exercise (walking, stationary bike, <70% max HR) | Increase heart rate |
| 3 | Sport-specific exercise (running, skating drills — no head impact) | Add movement |
| 4 | Non-contact training drills, resistance training | Coordination and cognitive load |
| 5 | Full-contact practice after medical clearance | Restore confidence, assess functional skills |
| 6 | Return to play | Normal game play |
Treatment
First-line
- Initial relative rest (1-2 days) — physical and cognitive — followed by GRADUAL return to activity
- Symptom-limited aerobic activity (sub-symptom-threshold exercise like stationary bike) within 24-48 h is now recommended (Buffalo Treadmill Test guides intensity)
- Acetaminophen for headache (avoid NSAIDs/aspirin in the first 24-48 h due to bleeding risk, though increasingly considered safe)
- Sleep hygiene, hydration, avoid alcohol and recreational drugs
- Return-to-learn before return-to-play — graduated school accommodations as needed
- Graduated return-to-play protocol (6-step Berlin/Amsterdam consensus): only progress when asymptomatic at the prior step; no full contact until cleared by clinician
Second-line / adjunct
- Targeted therapy by dominant symptom: vestibular therapy for dizziness, oculomotor therapy for visual symptoms, cervical PT for neck pain, cognitive behavioral therapy for mood/sleep
- Migraine prophylaxis (amitriptyline, propranolol, topiramate) for persistent post-traumatic headache
- Neuropsychological testing for prolonged cognitive symptoms
- Avoid return to contact sport until full recovery; consider permanent retirement after multiple concussions or persistent symptoms
Complications
- Persistent post-concussive symptoms (>1 month) in up to 30-40%
- Second impact syndrome — rare but catastrophic diffuse cerebral edema from repeat head injury before recovery; pediatric athletes at highest risk
- Post-traumatic epilepsy
- Chronic traumatic encephalopathy (CTE) — neurodegenerative tauopathy associated with repetitive head impacts; diagnosed only postmortem
- Depression, anxiety, PTSD
- Vocational and academic impairment
PANCE pearls
- Loss of consciousness is NOT required to diagnose concussion (occurs in <10% of sports concussions).
- 'Strict rest' (cocoon therapy) for >2 days is HARMFUL — early symptom-limited activity improves outcomes (Amsterdam consensus 2023).
- Never return an athlete to play on the same day of a suspected concussion.
- Headache patterns matter: persistent post-traumatic headache often resembles migraine and responds to migraine treatment.
- Anyone with suspected concussion needs a graduated return-to-learn AND return-to-play plan — academic and athletic stepwise progression.
References
- Amsterdam Consensus 2023 — Consensus Statement on Concussion in Sport — 6th International Conference (Patricios et al., BJSM 2023)
- CDC mTBI 2018 — CDC Guideline on Diagnosis and Management of Mild Traumatic Brain Injury Among Children (Lumba-Brown et al., JAMA Pediatr 2018)
- Canadian CT Head Rule — The Canadian CT Head Rule for Patients with Minor Head Injury (Stiell et al., Lancet 2001)
- AAN 2013 — Evaluation and Management of Concussion in Sports (Giza et al., Neurology 2013)
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