Concussion Signs and Symptoms
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
Diagnostic Criteria
A concussion diagnosis requires at least one of four key signs following head trauma 2:
- Altered mental state immediately after injury 2
- Posttraumatic amnesia for less than 24 hours 2
- Loss of consciousness for less than 30 minutes 2
- Other focal and transient neurologic dysfunction 2
The diagnosis is established when a patient experiences direct or indirect transmission of kinetic energy to the head AND demonstrates at least one of these findings within 24 hours 2.
Physical Symptoms
The most common physical manifestations include 1:
- Headache (most frequent symptom overall) 1, 3
- Dizziness and balance problems 1, 3
- Nausea and vomiting 1, 3
- Fatigue and drowsiness 1, 3
- Light sensitivity (photophobia) and noise sensitivity (phonophobia) 1
- Visual problems, including blurred vision and double vision 1
- Numbness 1
Cognitive Symptoms
Cognitive impairments manifest as 1, 3:
- Difficulty concentrating and remembering 1, 3
- Feeling "slow" or "foggy" (mental fogginess), which may predict slower recovery 1
- Confusion and amnesia (both retrograde and anterograde) 1
- Slowed thinking and problems with executive functions 2
Amnesia serves as an important indicator of more serious injury and should be systematically assessed 1.
Emotional and Behavioral Symptoms
Common emotional changes include 1, 3:
Sleep Disturbances
Sleep-related symptoms encompass 1:
Critical Red Flag Symptoms Requiring Emergency Evaluation
Loss of consciousness occurs in less than 10% of concussions but represents a critical red flag warranting immediate emergency evaluation. 1 Patients must return immediately to the emergency department if they develop 2, 1:
- Repeated vomiting 2, 1
- Worsening headache 2
- Increased sleepiness 2
- Seizures 2, 1
- Focal neurologic deficits 2
- Abnormal behavior 2
- Confusion or problems remembering 2
- Altered mental status 1
- Signs of skull fracture 1
Temporal Pattern and Clinical Course
Symptoms may present immediately or evolve over minutes to hours following the injury, and can be delayed in onset. 1 Most patients (80-85%) achieve complete symptom resolution within 3 months, but 15-20% develop persistent postconcussion syndrome requiring specialist referral 2, 3.
Risk Factors for Prolonged Recovery
High-risk patients include those with 2, 3:
- History of multiple concussions 2
- Female gender 2, 3
- Age over 40 years 2, 3
- Pre-existing mood disorders 2, 3
- The triad of headache, nausea, and dizziness at initial presentation (50% chance of developing post-concussion syndrome at 6 months) 3
- High initial symptom burden 3
Assessment Approach
Any patient with a single symptom or sign of head injury must be immediately removed from activity and not return that day, regardless of symptom resolution, following the "when in doubt, sit them out" principle. 1 Clinicians should recognize both obvious signs (fluctuating levels of consciousness, balance problems, memory and concentration issues) and common self-reported symptoms 4.
Systematic symptom assessment using graded checklists provides objective tracking across serial evaluations, allowing quantification of symptom severity on a 0-6 scale across all domains 1. In addition to thorough clinical evaluation, formal cognitive and postural stability testing is recommended to assist in objectively determining injury severity 4. Baseline testing with concussion-assessment measures is recommended to establish the individual's "normal" preinjury performance 4.
Important Clinical Considerations
The symptoms are nonspecific and cannot be explained by drug, alcohol, medication use, cervical injuries, peripheral vestibular dysfunction, or other comorbidities, requiring careful differential diagnosis to exclude other causes 1. Symptoms result from a neurometabolic cascade triggered by biomechanical forces, increasing local energy demand amid decreased cerebral blood flow and mitochondrial dysfunction 1.
Management Principles
Begin sub-symptom threshold aerobic exercise immediately rather than strict rest, as complete rest beyond 2-3 days may delay recovery. 3 Patients should start light aerobic activity at 60-70% of maximum heart rate for 15-20 minutes daily, gradually increasing duration and intensity as tolerated 3. Implement partial cognitive rest with screen time limited to 30-minute intervals with breaks, reduced reading, and shortened work/school days 3.