Current theories regarding Post-Concussion Syndrome (PCS) are diverse and often contradictory. Since every brain injury is unique, a singular description rarely fits everyone's specific reality. I have compiled this encyclopedia to bridge that gap. Corrections and insights are welcome.

1. The Mechanics of Impact: Absorption of Force

From a physics perspective, when your head sustains an impact, that kinetic energy must be absorbed. The destination of this force determines the outcome:

• Scalp: If the scalp absorbs the majority of the force, it results in a subcutaneous hematoma (a "goose egg").
• Skull: Our skulls are exceptionally hard. While usually resilient, the fluid between the skull and the brain can create an "echo effect," causing brief vertigo (typically under 30 seconds). If the force exceeds the skull's threshold, a fracture occurs, and the residual energy is transmitted directly to the brain, leading to an open traumatic brain injury (TBI).
• Neck: If the neck absorbs the force, it can disrupt cerebral blood flow. Our brain's energy supply relies on vessels in the neck; injuries here mimic concussion symptoms by causing metabolic crises.
• Vestibular System: This is the neural link between the eyes and the brain. Damage here leads to dizziness and light sensitivity.
• The "Invisible" Injury: While scalp and skull damage are visible, neck and vestibular issues are often "invisible." Many concussion clinics successfully treat these "invisible" injuries. However, if the force bypasses these filters and is absorbed directly by the brain—and symptoms arise—that is where a true concussion begins.

2. The Nature of Concussion: Wiring and Structural Damage

The brain’s consistency is akin to tofu, composed of neurons connected by a vast "spiderweb" of axons—long, thread-like fibers. Electrical signals travel along water molecules within these axons, which are tightly wrapped to ensure signal integrity.

• The Energy Crisis: Upon impact, axons are stretched and compressed. This temporary stretching causes water molecules to leak and exchange with the extracellular environment. This "leakage" creates a temporary energy gap. This gap usually resolves automatically as the brain replenishes its energy stores.
• Diffuse Axonal Injury (DAI): Because the brain is a unified organ, an impact causes "Diffuse Axonal Injury"—nearly all regions experience some degree of axonal stretching. Physics dictates there is usually a "stress point" where force is most concentrated, resulting in specific symptoms. Subtle stretching that allows for full recovery is often termed a "Sub-concussion."
• The "New Normal": If the impact velocity is high, the stress point suffers significant damage to axons, microtubules, and the myelin sheath. Glial cells rush to repair these areas, a process that typically concludes within three months. If symptoms persist beyond this window, it is classified as Post-Concussion Syndrome (PCS).
• Structural Reality: PCS is essentially a structural injury. Axonal shearing, micro-fractures, or myelin loss means the brain will never return to its "factory settings." The Corpus Callosum and Cingulum Bundle are the most common stress points; damage here inevitably leads to cognitive and personality changes. This is the "New Normal."

3. Treatment: The Hard Truth

The confusion surrounding "concussion treatment" stems from overly broad definitions.

• Type 1 (Non-Structural): If you haven't suffered structural damage and your symptoms stem from neck or vestibular issues, you can "recover" by treating those areas.
• Type 2 (Structural): True PCS—mild TBI with structural changes—cannot be "cured" in the traditional sense. It is a lifelong alteration.
• The Role of Rehabilitation: Modern research shows that controlled exercise (rather than total rest) helps glial cells by secreting neurosynaptic substances. However, cognitive training is about optimization, not restoration. It helps a disabled person return to work, but it cannot return you to your "original self." If the hardware is altered, the "original you" is a closed chapter.

When I was in middle school, I was bullied often. The bully would smack my head and run away.
It wasn't very hard, and there were basically no symptoms, but I was terrified. I didn't dare tell my teachers or parents.

In the third year of middle school, the bullying got worse. But home was still my safe, familiar place. The fear of being bullied would disappear the moment I got home.

Then, in the second half of that school year, the kid who often hit me jumped up while no one else was in the classroom and smashed my head really hard.

I saw it coming and tensed my neck. My head barely moved.
I felt nothing at first, no pain. But then when I tried to move, my limbs wouldn’t obey. I tried to speak, but no sound came out.
I forced myself to move — my legs could still move, but they were clumsy, and so were my hands.
So I used my hands to drag myself back to my seat. I slept for ten minutes. When I woke up, everything seemed normal again.
I wanted to report him, but I didn’t dare. The silence had cost too much already. He looked scared too, so I thought it was over — he wouldn’t dare hit me again.

But a week later, he came back. This time I wasn’t ready.
He punched me with his fist, very hard. My head moved a lot.
In that moment, my mind went blank. My thoughts became crystal clear — and different. It felt like my brain went from multi-core to single-core. I was forced from an active state into a “calm” state.
I held my head and said, “Are you trying to kill me?” He laughed and said, “My hand hurts from hitting you.”

This time, I didn’t lose control of my limbs — but I slowly lay down. I don’t know if I wanted to make the situation bigger or if my body just gave out. I felt very sleepy and wanted to fall asleep right there. But class would come back soon, and I was afraid someone would step on me.
So I crawled back to my seat and slept for three hours.

When I woke up, school was over. Everything around me felt strange. I knew something was wrong with my brain. I went home and watched TV — everything felt different. The show’s content felt different from before. I couldn’t follow lessons. I didn’t do my homework that night.

The next day, I tried to do my homework. I pushed through with this strange feeling and a very slow, clumsy brain. I finished the math problems.
A few days later, the bullies tried to hit my head again. I just stood there, thinking, “I don’t care if I die.” Someone stopped them. He never hit me again.

About a week later, my brain slowed down less. I could follow classes again. I could think. But my cognition had changed.
Before, when I looked at things, my instinctive thoughts were many and passionate. When I focused, it was orderly and fast. I would be so absorbed in class that the world around me disappeared.
Now, when I look at things, I have few thoughts and little passion. When I focus, I’m slow and often forget where my thoughts were going. If I try to go fast, I derail. In class, I focus for two seconds and then get distracted. Also, I get tired much more easily.
Other than that, everything else seemed the same. I don’t know if it was a concussion, but I think it was. After that hit, I had only cognitive issues. No retrograde amnesia, no loss of consciousness, no vomiting, no light or sound sensitivity, no headache or dizziness. Just a brain that didn’t work as well.

In high school, I wasn’t bullied anymore. I was happy enough, but the cognitive change affected me. I wasn’t as joyful as before. I didn’t get into a good university. At work, learning new things is hard. I get tired easily.

Nine years later, I still couldn’t let it go. I went to a hospital and told my story. The doctor ordered an MRI — completely normal.
Four more years passed. I learned about brain injury, that a normal MRI doesn’t mean nothing happened. And I saw that many people with post-concussion syndrome had symptoms that matched mine exactly.
I broke down. I had been at peace because I hoped time would heal everything, that I could ignore it. But when I learned about permanent brain damage, all the memories came flooding back to 13 years ago. I suddenly remembered why I always felt my brain didn’t work well. I recalled being hit into a concussion. I had buried that memory.
I fell into depression. I rushed to a psychiatric hospital.
One doctor said it was psychological. Another said there might indeed be brain damage that instruments can’t detect, but after hearing my story he doubted it — after all, a 16-year-old boy hit on the hard part of the skull (between the forehead and crown) — how could that cause such serious brain damage?
But my symptoms are real. My cognition changed after that day. I have to get better.
I saw a psychologist who thought I might have CPTSD.
Then I saw another neurologist. He ordered ERP and fNIRS. Both were abnormal.
I asked him what was wrong. He said my brain was damaged by that hit. He said the MRI was done too late — there might have been tiny bleeding spots at the time, but they were absorbed, so nothing shows up now.
I asked if I could recover. He said, “Try, maybe it’ll help, but probably not.”
I was crushed. Despair set in.

I traveled to Beijing. Their doctors said the P300 abnormalities don’t prove much. They ordered another MRI and DTI — both completely normal.
I consulted several well-known professors and concussion associations. They all said that with normal imaging, there can’t be any residual effects, and they sent me to psychiatrists.
I know I have psychological issues, but the cognitive change after that punch is not fake. I don’t want to fix my obsession with the event — I want to fix the event itself.

My ERP and fNIRS showed prolonged MMN and reduced brain connectivity — which perfectly matches my condition.
It’s been 15 years. I still haven’t found a treatment. After that concussion, everything looked and felt different. My thinking is sparse. I can’t concentrate. Is this permanent brain damage? I don’t know. But I have never recovered.