What are the signs and symptoms of a concussion?

Signs and Symptoms of Concussion

Concussion presents with a constellation of symptoms across four distinct domains: physical, cognitive, emotional, and sleep-related, with headache being the most frequently reported symptom, occurring in the majority of cases. 1

Four Symptom Domains

Physical Symptoms

The physical manifestations are the most commonly recognized:

• Headache (most frequent symptom overall) 1
• Dizziness and balance problems 1
• Nausea and vomiting 1
• Fatigue and drowsiness 1
• Light sensitivity (photophobia) 1
• Noise sensitivity (phonophobia) 1
• Visual problems and blurred vision 1
• Double vision 1
• Numbness 1

Cognitive Symptoms

These reflect the functional brain disturbance:

• Difficulty concentrating 1
• Difficulty remembering 1
• Feeling "slow" or "foggy" (mental fogginess may predict slower recovery) 1
• Confusion 1
• Amnesia (both retrograde and anterograde) 1

Emotional/Behavioral Symptoms

Mood changes are common but often overlooked:

• Irritability 1
• Sadness 1
• Nervousness 1
• Feeling more emotional 1
• Anxiety 1
• Depression 1

Sleep Disturbances

Sleep pattern changes occur frequently:

• Trouble falling asleep 1
• Excessive sleep 1
• Loss of sleep 1
• Drowsiness 1

Critical Signs Requiring Immediate Attention

Loss of consciousness (LOC) occurs in less than 10% of concussions but represents a critical red flag warranting immediate emergency evaluation. 1, 2 The absence of LOC does not rule out concussion—this is a common pitfall that leads to underdiagnosis. 3

Additional red flags mandating emergency medical services activation include: 2

• Worsening or severe headache
• Repeated vomiting
• Altered mental status
• Seizure activity
• Visual changes
• Signs of skull fracture (Battle's sign, raccoon eyes, hemotympanum, CSF otorrhea/rhinorrhea)

Temporal Pattern and Evolution

Symptoms may present immediately or evolve over minutes to hours following the injury, and can be delayed in onset. 1 This delayed presentation complicates diagnosis, as symptoms may not be apparent during initial evaluation. 1

Resolution typically follows a sequential course, with most symptoms resolving within the first 3 months. 4 However, 15-20% of patients develop persistent symptoms beyond this timeframe. 1, 3

Important Clinical Considerations

Amnesia serves as an important indicator of more serious injury and should be systematically assessed. 1 Evaluate both:

• Retrograde amnesia (events before injury)
• Anterograde amnesia (events after injury)

Note that retrograde amnesia symptoms may falsely appear to improve as patients hear others discuss the injury events. 1

The symptoms are nonspecific and cannot be explained by drug, alcohol, medication use, cervical injuries, peripheral vestibular dysfunction, or other comorbidities. 1 This requires careful differential diagnosis to exclude other causes.

Pathophysiological Basis

Symptoms result from a neurometabolic cascade triggered by biomechanical forces, increasing local energy demand amid decreased cerebral blood flow and mitochondrial dysfunction. 1, 3 This represents a functional disturbance rather than structural injury, explaining why standard neuroimaging appears normal. 1, 3

Assessment Approach

Any child with a single symptom or sign of head injury must be immediately removed from activity and not return that day, regardless of symptom resolution. 2 The "when in doubt, sit them out" principle is paramount. 3

Systematic symptom assessment using graded checklists provides objective tracking across serial evaluations. 1 These tools allow quantification of symptom severity on a 0-6 scale across all domains, facilitating monitoring of recovery trajectory. 1