Concussion

A concussion is a mild traumatic brain injury caused by a blow to the head or body that causes the brain to move rapidly within the skull. It temporarily disrupts brain function and can affect memory, judgment, reflexes, balance, and coordination. Loss of consciousness is not required for a concussion to occur — many people with concussion never pass out.

Most people recover fully with appropriate rest and a gradual return to activity. Repeated concussions, especially before full recovery, increase the risk of longer-lasting symptoms. Recognition, removal from play or risk, and a structured recovery plan are essential, particularly in sports and for children and adolescents.

Symptoms may appear immediately or hours later and can include:

• Headache or pressure in the head
• Nausea or vomiting
• Dizziness, balance problems, or lightheadedness
• Blurred or double vision
• Sensitivity to light or noise
• Feeling sluggish, hazy, foggy, or confused
• Difficulty concentrating or remembering
• Mood changes — irritability, sadness, or nervousness
• Sleep changes — sleeping more or less than usual, or trouble falling asleep
• Loss of consciousness (in some cases)

In children, symptoms may also include excessive crying, listlessness, changes in nursing or eating, and loss of interest in favorite toys.

Concussion results from biomechanical forces transmitted to the brain — a direct hit to the head or an indirect force (e.g., whiplash) that causes rapid acceleration-deceleration. Common settings include contact sports, falls, bicycle and motor-vehicle crashes, and assaults. The injury disrupts neuronal function and can cause temporary changes in brain metabolism and blood flow without necessarily showing structural damage on standard CT scans.

Risk factors include:

• Participation in contact or collision sports (football, soccer, hockey, rugby, boxing, etc.)
• Previous concussion — increases risk of another and of longer recovery
• Falls, especially in young children and older adults
• Motor-vehicle and bicycle crashes without proper restraints or helmets
• Military combat exposure
• Physical abuse

Possible complications include:

• Prolonged post-concussion symptoms (headache, dizziness, cognitive and mood problems lasting weeks to months)
• Second-impact syndrome — rare but catastrophic brain swelling if a second injury occurs before recovery (especially concerning in young athletes)
• Increased risk of further concussions
• In rare cases with repeated injuries over years, associations with chronic traumatic encephalopathy (CTE) — still an area of active research
• Mental-health effects, including anxiety and depression

Prevention strategies:

• Wear appropriate, well-fitted helmets for cycling, motorcycling, skiing, contact sports, and certain work activities (helmets reduce skull fracture and severe injury risk; they do not eliminate concussion)
• Use seat belts and child safety seats
• Follow sports rules and fair-play practices; coach and athlete education on safe technique
• Strengthen neck muscles as part of conditioning (may modestly help)
• Fall-prevention measures for older adults and home safety for young children
• Never return to play the same day as a suspected concussion

Diagnosis is clinical, based on mechanism of injury and symptoms. Tools include:

• Symptom checklists and standardized assessments (e.g., SCAT for sports)
• Neurologic examination including balance and cognitive screening
• CT scan when red-flag features suggest possible hemorrhage or more serious injury (most concussions have normal CT)
• MRI in selected prolonged or atypical cases
• Neuropsychological testing when return-to-learn or return-to-play decisions are complex

There is no single biomarker test in routine clinical use yet.

Anyone with a suspected concussion should be evaluated by a healthcare professional. Seek emergency care for:

• Worsening or severe headache
• Repeated vomiting
• Increasing confusion, restlessness, or agitation
• Seizures
• Unequal pupils, double vision, or other vision changes
• Weakness, numbness, or decreased coordination
• Slurred speech
• Inability to wake up or unusual drowsiness
• Clear fluid or blood from the nose or ears

These may indicate a more serious brain injury.

Management emphasizes relative rest followed by gradual return to activity:

• Acute phase — brief relative physical and cognitive rest (usually 24–48 hours); avoid complete prolonged isolation in a dark room
• Symptom-limited activity — light activity that does not significantly worsen symptoms, then stepwise increase
• Return-to-learn — graded school accommodations before full academic load
• Return-to-play — supervised, stepwise protocol only after symptoms have resolved at rest and with cognitive load; medical clearance required
• Headache management with clinician-guided analgesics (avoid overuse)
• Physical therapy for neck and vestibular issues when indicated
• Referral to specialized concussion clinics for prolonged recovery
• Address sleep, mood, and migraine-like features as needed

Athletes must not return to contact risk until fully cleared.

Helpful recovery steps:

• Follow the staged activity plan from your clinician
• Prioritize sleep; keep a regular schedule
• Limit screen time if it worsens symptoms, then reintroduce gradually
• Stay hydrated and eat regular meals
• Avoid alcohol and sedating medicines not approved by your clinician
• Do not drive until cleared if reaction time or vision is affected
• Report worsening symptoms promptly
• Be patient — recovery time varies; children and adolescents often need longer

Bring:

• Description of the injury mechanism and any loss of consciousness
• Full list of symptoms and when they started
• Prior concussion history
• Medicines and supplements
• School or sports requirements and timelines
• Questions about return-to-learn, return-to-play, and expected recovery