Concussion: Understanding, Diagnosis, and Recovery

What Is a Concussion?

A concussion is a traumatic brain injury (TBI) caused by a bump, blow, or jolt to the head that changes how the brain functions. Importantly, you do not have to lose consciousness to have a concussion — in fact, loss of consciousness occurs in fewer than 10% of concussions.

The brain sits inside the skull surrounded by cerebrospinal fluid. When the head is suddenly accelerated or decelerated, the brain may bounce around, twist, or move inside the skull, stretching and damaging brain cells and triggering neurochemical changes.

Concussions account for approximately 1.6–3.8 million sports-related TBIs annually in the United States. They occur across all sports and in everyday accidents (vehicle collisions, falls).

Pathophysiology

At the cellular level, concussion causes:

Ionic flux: Disrupted ion gradients across cell membranes
Neurochemical cascade: Excitatory neurotransmitter release leading to energy crisis
Metabolic depression: Reduced cerebral glucose utilization — the brain struggles to meet energy demands
Axonal injury: Stretching or disruption of axons (nerve fibers)

The brain needs time to restore normal neurochemical and metabolic function. Returning to activity before this happens risks a more severe injury with repeat trauma.

Causes

Contact sports: Football, soccer, hockey, rugby, lacrosse, basketball
High-impact sports: Skiing, cycling, equestrian
Motor vehicle accidents
Falls (especially in the elderly)
Direct head-to-head, head-to-surface, or head-to-object collision

Symptoms

Concussion symptoms vary widely and may not all appear immediately:

Cognitive: Difficulty thinking clearly, feeling slowed down, difficulty concentrating, memory problems (especially short-term memory), confusion

Physical: Headache (most common symptom), nausea or vomiting, dizziness, balance problems, blurred or double vision, light sensitivity (photophobia), noise sensitivity (phonophobia), fatigue

Emotional/Behavioral: Irritability, sadness, emotional lability, anxiety, feeling "not right"

Sleep: Sleeping more or less than usual, trouble falling asleep

Red Flag Symptoms — Seek Emergency Care Immediately

The following symptoms may indicate a more serious brain injury (bleeding, significant swelling):

One pupil larger than the other
Repeated vomiting
Worsening headache that is "the worst headache of your life"
Seizures
Cannot be awakened
Slurred speech, increasing confusion, or deteriorating level of consciousness
Numbness or weakness in the limbs

If red flags are present: Call 911 or go to the emergency room immediately.

Diagnosis

Concussion is a clinical diagnosis — there is no single test that definitively confirms it. Diagnosis is based on:

History and symptom assessment:

Mechanism of injury
Presence and duration of symptoms
SCAT (Sport Concussion Assessment Tool) — standardized assessment used sideline and clinically

Neurological examination:

Cognitive assessment (orientation, memory, concentration)
Balance testing (modified BESS — Balance Error Scoring System)
Coordination
Symptom severity rating

Imaging:

Standard CT scans and MRI are typically normal after concussion — they rule out structural injury (bleeding, fracture) but cannot "show" a concussion
Advanced MRI techniques (diffusion tensor imaging) are research tools, not clinical standard

Baseline testing: ImPACT and other computerized neurocognitive tests provide baseline scores for athletes to compare to post-injury assessments.

Treatment and Management

Initial Rest

Physical and cognitive rest for 24–48 hours acutely
Important: Prolonged strict rest (more than 2–3 days) is no longer recommended — it delays recovery in most patients
Limit screen time, bright lights, loud noises, and cognitively demanding tasks initially

Graduated Return to Activity

Concussion management follows a structured return-to-activity and return-to-sport protocol. Each stage requires being symptom-free for at least 24 hours before advancing:

Stage	Activity
1	Symptom-limited daily activity — walking, light daily tasks
2	Light aerobic exercise — walking, swimming (no resistance training)
3	Sport-specific exercise — running drills, skating
4	Non-contact training drills
5	Full-contact practice after medical clearance
6	Return to competition

Medical clearance is required before contact return. A physician or trained clinician must confirm the athlete is symptom-free and neurologically normal before final clearance.

Persistent Post-Concussion Symptoms (Post-Concussion Syndrome)

Most concussions (80–90%) resolve within 7–10 days. When symptoms persist beyond 4 weeks, this is termed post-concussion syndrome — and may require multidisciplinary management including:

Vestibular (balance) physical therapy
Vision therapy
Cervicogenic treatment (neck injury component)
Neuropsychological support
Medication management (headache, sleep, mood)

Second Impact Syndrome

Second impact syndrome is a rare but potentially fatal condition that occurs when a second concussion is sustained before full recovery from the first. The result is rapid, massive cerebral swelling that can be fatal or cause permanent disability. This is the primary reason strict return-to-play protocols must be followed.