Medicine
Symptoms of Concussion
Quick fact
Only about 10% of concussions involve being knocked out; the majority occur without any loss of consciousness.
Why this is interesting
A concussion can happen without a loss of consciousness—so what are the telltale signs that your brain has been injured?
Read the full explanation
Understanding Symptoms of Concussion
Concussion symptoms are not just a headache. They fall into four main categories: physical (e.g., headache, dizziness, nausea), cognitive (e.g., confusion, difficulty concentrating, memory problems), emotional (e.g., irritability, sadness, anxiety), and sleep-related (e.g., drowsiness, insomnia). These symptoms can appear immediately after the injury or develop over hours to days. For example, a student might feel fine right after a fall but later struggle to follow a conversation or feel unusually tired. The key is that symptoms reflect the brain's temporary dysfunction, not structural damage visible on standard scans.
A deeper explanation
Symptoms arise from a metabolic cascade triggered by the impact. The brain's neurons stretch and undergo a rapid influx of ions, leading to an energy crisis as cells work to restore balance. This disrupts normal communication between neurons, causing the varied symptoms. For instance, dizziness often results from injury to the vestibular system, while cognitive fog stems from impaired axonal function in networks like the frontal lobe. Understanding symptoms matters because they guide diagnosis and recovery—returning to sports or intense mental activity too soon risks prolonging symptoms or causing second impact syndrome, a rare but often fatal condition.