Understanding Concussion: Definition, Workup, Symptoms, and Treatment
A concussion is a mild traumatic brain injury caused by biomechanical forces to the head, face, neck, or body that transmit impact to the brain, resulting in immediate but typically transient neurological dysfunction without structural brain damage on standard imaging 1.
What Happens in a Concussion
The injury triggers a neurometabolic cascade that increases local brain energy demand while simultaneously decreasing cerebral blood flow and causing mitochondrial dysfunction 1. This represents a functional disturbance rather than structural injury, which is why standard neuroimaging (CT, MRI) appears normal 1.
Clinical Diagnosis Criteria
Concussion is diagnosed clinically when at least one of the following occurs after head trauma 2:
- Any alteration of mental state immediately after injury
- Posttraumatic amnesia lasting less than 24 hours
- Loss of consciousness for less than 30 minutes
- Glasgow Coma Scale score of 13-15
- Other focal and transient neurologic dysfunction
Important caveat: Symptoms may evolve over minutes to hours rather than appearing immediately, and loss of consciousness is NOT required for diagnosis 1.
Symptoms Presentation
Concussion symptoms fall into four distinct domains 3:
Physical Symptoms
- Headache (most common)
- Dizziness
- Blurred or double vision
- Nausea
- Neck pain
- Fatigue
- Light and noise sensitivity
- Sleep disturbance
Cognitive Symptoms
- Slowed thinking
- Difficulty with attention and concentration
- Memory problems
- Executive function deficits
Emotional/Behavioral Symptoms
- Irritability
- Emotional lability
- Changed emotional responsivity
- Quickness to anger
Sleep Disturbances
- Insomnia or hypersomnia
- Disrupted sleep patterns
Workup and Evaluation
Initial Assessment
The primary goal is ruling out acute intracranial pathology requiring neurosurgical intervention 3. Look specifically for:
- Red flags indicating need for emergent imaging: worsening headache, repeated vomiting, seizures, focal neurologic deficits, declining mental status
- Mechanism of injury details
- Timeline of symptom onset and evolution
- Assessment across all four symptom domains
Diagnostic Tools
While concussion remains a clinical diagnosis, objective tools can supplement evaluation 4:
- Standardized cognitive testing
- Ocular tracking assessments
- Neurophysiological measures
Neuroimaging
Standard structural neuroimaging (CT/MRI) will be normal in concussion 1. Imaging is indicated only when:
- Red flag symptoms suggest intracranial hemorrhage or structural injury
- Clinical deterioration occurs
- Mechanism suggests high-risk injury
Critical pitfall: Do not expect imaging to confirm concussion diagnosis—it won't. The diagnosis is clinical.
Treatment Approach
Acute Phase (First 48 Hours)
Avoid strict rest—it is detrimental 1. The 2023 consensus guidelines found evidence of harm from prolonged strict rest.
Instead, implement:
- Brief period of relative rest (24-48 hours maximum)
- Early education and reassurance 2
- Immediate removal from risk of further injury 5
- Light cognitive and physical activities as tolerated
Subacute Phase (2 Days to 4 Weeks)
For adolescents specifically, exercise is strongly recommended as appropriate therapy for acute concussion 1. This represents the strongest evidence-based recommendation from the 2023 consensus statement.
Treatment strategy:
- Graded aerobic exercise starting early, monitoring for symptom exacerbation 4
- Incremental return to activities of daily living 6
- Supervised progressive return to cognitive demands (school/work)
- Avoid high-intensity physical activity (shown to be detrimental) 1
Symptom-Targeted Interventions
For specific symptom profiles 2:
- Vestibular symptoms: Vestibular rehabilitation (weak recommendation, low-quality evidence)
- Neck pain: Manual treatment of neck and spine (weak recommendation)
- Headache: Targeted headache management strategies 6
- Psychological symptoms: Psychological treatment (weak recommendation)
Persistent Symptoms (>4 Weeks)
Approximately 15-34% of patients develop persistent postconcussion symptoms (PPCS) 1, 2. When symptoms persist beyond 4 weeks:
- Consider interdisciplinary coordinated rehabilitative treatment 2
- Evaluate for coexisting conditions: cervical injury, vestibular dysfunction, psychological factors, pre-existing conditions 1
- Specialty referrals as indicated by symptom profile
- Continue graded exercise programs
- Oculomotor vision treatment (good clinical practice recommendation based on consensus) 2
Important consideration: PPCS symptoms are nonspecific and may be attributable to factors other than the concussion itself 1. Assess for preexisting, coexisting, and resulting comorbidities.
Evidence Quality Note
The 2023 PM&R consensus statement 1 represents the most recent high-quality guideline evidence. However, the panel acknowledged that evidence for most interventions remains limited to small trials of moderate to low quality, with the notable exception of exercise in adolescents. The 2021 JAMA Network Open guideline 2 similarly found only weak scientific support (very low to low certainty evidence) for commonly applied interventions in persistent symptoms.
Recovery Timeline
Most concussions resolve within 2-3 weeks 2. However:
- 34-44% experience symptoms at 3-6 months 2
- 5-20% experience symptoms at 12 months 2
- Recovery typically follows a sequential course but can be prolonged 1
Critical Clinical Pitfalls to Avoid
- Do NOT prescribe prolonged strict rest—evidence shows harm 1
- Do NOT rely on neuroimaging to diagnose concussion—it will be normal 1
- Do NOT allow high-intensity exercise in acute phase—evidence shows harm 1
- Do NOT assume all persistent symptoms are from concussion—evaluate for other causes 1
- Do NOT delay early mobilization and light activity—early gradual return is beneficial 4, 5