I believe most people care about treatment. First of all, to discuss this issue, you must distinguish whether you have functional symptoms or structural symptoms.

These two are completely different. The former is like a cold; you can expect a sudden and complete recovery one day because your brain is perfectly healthy—it just lost its way. Structural damage, on the other hand, is true TBI. Your brain is genuinely broken, only so microscopically that it cannot be seen on MRI. For a long time, doctors relied on MRI to determine whether structural damage existed, which caused a lot of confusion—mixing up concussion with invisible brain injury.

Therefore, as a patient, you first need to know whether you are functional or structural. That is the most important thing.

Currently, the most reliable method is DTI—a special MRI sequence that observes the direction of water flow in the brain. By finding whether your pipes are broken, you can determine if it is brain injury. Only by doing this can you know if you truly have structural damage. Doctor's judgment and standard MRI are unreliable.

Once you have the result, read on.

Functional damage: Congratulations, your brain is healthy. You should aim for a full reversal through effort.

1. When you suffer a blow to the head, you should remember that not only the brain is inside your skull. If you are dizzy, check for ear stones (BPPV). If you are light-sensitive, see an eye doctor. If you have headaches, check your neck. In short, not only brain injury causes symptoms. Only connective tissue, the brain, and heart muscle cells cannot repair themselves. As long as your brain is not damaged, no matter what other parts are injured, you will recover completely. Leave it to the doctors.
2. Mindfulness therapy. After a concussion, many people fall into anxiety and worry. They cannot calm down. It is just that you are too afraid, causing various physical reactions. Try to calm your mind, accept that you "feel not normal," instead of thinking about what to do. You may find that one day when you no longer think about it, you will be fully healed.
3. Exercise. I believe many people scoff at this, thinking it is as trivial as "eat more apples to stay healthy." But in fact, after a concussion, many areas have insufficient blood flow, which can cause cognitive problems. You can use fNIRS or fMRI to detect blood flow issues in the brain. Through high-intensity exercise, when blood circulation speeds up, your brain will suddenly be flooded with blood, and your brain fog and cognitive problems will disappear. Your brain is not broken; it just did not receive enough power after a power outage.

There are also many other therapies. Clinics like ConcussionFX and UPMC are dealing with these issues. If you have no structural damage, your symptoms can fully recover.

Structural damage: First, I have to be honest. Whatever symptoms you have, you must be prepared to live with them for the rest of your life. This is a completely different problem from a simple concussion. There is a wound inside your brain. You cannot be cured. Your goal is to accept the remaining symptoms and live out the rest of your life.

1. Even with structural damage, it is still a form of concussion. You can try the recovery methods that the lucky ones with functional damage use to solve the problems you can. Of course, do not expect obvious effects, but if some symptoms improve, what remains is the wound.
2. Neuroplasticity. When a wound appears in your brain, your brain will spontaneously reconnect to maximize functional recovery. Therefore, maintaining what you used to do is always effective. Do not give up your habits just because you feel you have lost abilities. Neuroplasticity has a window period. If you cannot recover within three months, your brain will consider this as "you" (just like the 80-year-old grandfather downstairs), and you will find it very difficult to achieve breakthrough recovery. Then you must accept the "new normal." Considering how microscopic the damage is, your brain has full capacity to compensate and achieve functional recovery.
3. Habit is also a power. Many patients with structural damage, after a year or two, even if their abilities have not recovered and DTI still shows the wound, still feel that they are fine. It is like getting a tooth filling. At first you are not used to the filled area, but soon you no longer notice it. The human brain's ability to habituate is very strong. When you carry the symptoms for a while, you will stop noticing them. In some situations, you may suddenly have the thought, "This is how I should have felt before the brain injury," and fall into mourning, but it will not last long. Mentally, you have already healed. You have the strength to live the rest of your life.

I believe most people care about treatment. First of all, to discuss this issue, you must distinguish whether you have functional symptoms or structural symptoms.

These two are completely different. The former is like a cold; you can expect a sudden and complete recovery one day because your brain is perfectly healthy—it just lost its way. Structural damage, on the other hand, is true TBI. Your brain is genuinely broken, only so microscopically that it cannot be seen on MRI. For a long time, doctors relied on MRI to determine whether structural damage existed, which caused a lot of confusion—mixing up concussion with invisible brain injury.

Therefore, as a patient, you first need to know whether you are functional or structural. That is the most important thing.

Currently, the most reliable method is DTI—a special MRI sequence that observes the direction of water flow in the brain. By finding whether your pipes are broken, you can determine if it is brain injury. Only by doing this can you know if you truly have structural damage. Doctor's judgment and standard MRI are unreliable.

Once you have the result, read on.

Functional damage: Congratulations, your brain is healthy. You should aim for a full reversal through effort.

1. When you suffer a blow to the head, you should remember that not only the brain is inside your skull. If you are dizzy, check for ear stones (BPPV). If you are light-sensitive, see an eye doctor. If you have headaches, check your neck. In short, not only brain injury causes symptoms. Only connective tissue, the brain, and heart muscle cells cannot repair themselves. As long as your brain is not damaged, no matter what other parts are injured, you will recover completely. Leave it to the doctors.
2. Mindfulness therapy. After a concussion, many people fall into anxiety and worry. They cannot calm down. It is just that you are too afraid, causing various physical reactions. Try to calm your mind, accept that you "feel not normal," instead of thinking about what to do. You may find that one day when you no longer think about it, you will be fully healed.
3. Exercise. I believe many people scoff at this, thinking it is as trivial as "eat more apples to stay healthy." But in fact, after a concussion, many areas have insufficient blood flow, which can cause cognitive problems. You can use fNIRS or fMRI to detect blood flow issues in the brain. Through high-intensity exercise, when blood circulation speeds up, your brain will suddenly be flooded with blood, and your brain fog and cognitive problems will disappear. Your brain is not broken; it just did not receive enough power after a power outage.

There are also many other therapies. Clinics like ConcussionFX and UPMC are dealing with these issues. If you have no structural damage, your symptoms can fully recover.

Structural damage: First, I have to be honest. Whatever symptoms you have, you must be prepared to live with them for the rest of your life. This is a completely different problem from a simple concussion. There is a wound inside your brain. You cannot be cured. Your goal is to accept the remaining symptoms and live out the rest of your life.

1. Even with structural damage, it is still a form of concussion. You can try the recovery methods that the lucky ones with functional damage use to solve the problems you can. Of course, do not expect obvious effects, but if some symptoms improve, what remains is the wound.
2. Neuroplasticity. When a wound appears in your brain, your brain will spontaneously reconnect to maximize functional recovery. Therefore, maintaining what you used to do is always effective. Do not give up your habits just because you feel you have lost abilities. Neuroplasticity has a window period. If you cannot recover within three months, your brain will consider this as "you" (just like the 80-year-old grandfather downstairs), and you will find it very difficult to achieve breakthrough recovery. Then you must accept the "new normal." Considering how microscopic the damage is, your brain has full capacity to compensate and achieve functional recovery.
3. Habit is also a power. Many patients with structural damage, after a year or two, even if their abilities have not recovered and DTI still shows the wound, still feel that they are fine. It is like getting a tooth filling. At first you are not used to the filled area, but soon you no longer notice it. The human brain's ability to habituate is very strong. When you carry the symptoms for a while, you will stop noticing them. In some situations, you may suddenly have the thought, "This is how I should have felt before the brain injury," and fall into mourning, but it will not last long. Mentally, you have already healed. You have the strength to live the rest of your life.

I believe most people care about treatment. First of all, to discuss this issue, you must distinguish whether you have functional symptoms or structural symptoms.

These two are completely different. The former is like a cold; you can expect a sudden and complete recovery one day because your brain is perfectly healthy—it just lost its way. Structural damage, on the other hand, is true TBI. Your brain is genuinely broken, only so microscopically that it cannot be seen on MRI. For a long time, doctors relied on MRI to determine whether structural damage existed, which caused a lot of confusion—mixing up concussion with invisible brain injury.

Therefore, as a patient, you first need to know whether you are functional or structural. That is the most important thing.

Currently, the most reliable method is DTI—a special MRI sequence that observes the direction of water flow in the brain. By finding whether your pipes are broken, you can determine if it is brain injury. Only by doing this can you know if you truly have structural damage. Doctor's judgment and standard MRI are unreliable.

Once you have the result, read on.

Functional damage: Congratulations, your brain is healthy. You should aim for a full reversal through effort.

1. When you suffer a blow to the head, you should remember that not only the brain is inside your skull. If you are dizzy, check for ear stones (BPPV). If you are light-sensitive, see an eye doctor. If you have headaches, check your neck. In short, not only brain injury causes symptoms. Only connective tissue, the brain, and heart muscle cells cannot repair themselves. As long as your brain is not damaged, no matter what other parts are injured, you will recover completely. Leave it to the doctors.
2. Mindfulness therapy. After a concussion, many people fall into anxiety and worry. They cannot calm down. It is just that you are too afraid, causing various physical reactions. Try to calm your mind, accept that you "feel not normal," instead of thinking about what to do. You may find that one day when you no longer think about it, you will be fully healed.
3. Exercise. I believe many people scoff at this, thinking it is as trivial as "eat more apples to stay healthy." But in fact, after a concussion, many areas have insufficient blood flow, which can cause cognitive problems. You can use fNIRS or fMRI to detect blood flow issues in the brain. Through high-intensity exercise, when blood circulation speeds up, your brain will suddenly be flooded with blood, and your brain fog and cognitive problems will disappear. Your brain is not broken; it just did not receive enough power after a power outage.

There are also many other therapies. Clinics like ConcussionFX and UPMC are dealing with these issues. If you have no structural damage, your symptoms can fully recover.

Structural damage: First, I have to be honest. Whatever symptoms you have, you must be prepared to live with them for the rest of your life. This is a completely different problem from a simple concussion. There is a wound inside your brain. You cannot be cured. Your goal is to accept the remaining symptoms and live out the rest of your life.

1. Even with structural damage, it is still a form of concussion. You can try the recovery methods that the lucky ones with functional damage use to solve the problems you can. Of course, do not expect obvious effects, but if some symptoms improve, what remains is the wound.
2. Neuroplasticity. When a wound appears in your brain, your brain will spontaneously reconnect to maximize functional recovery. Therefore, maintaining what you used to do is always effective. Do not give up your habits just because you feel you have lost abilities. Neuroplasticity has a window period. If you cannot recover within three months, your brain will consider this as "you" (just like the 80-year-old grandfather downstairs), and you will find it very difficult to achieve breakthrough recovery. Then you must accept the "new normal." Considering how microscopic the damage is, your brain has full capacity to compensate and achieve functional recovery.
3. Habit is also a power. Many patients with structural damage, after a year or two, even if their abilities have not recovered and DTI still shows the wound, still feel that they are fine. It is like getting a tooth filling. At first you are not used to the filled area, but soon you no longer notice it. The human brain's ability to habituate is very strong. When you carry the symptoms for a while, you will stop noticing them. In some situations, you may suddenly have the thought, "This is how I should have felt before the brain injury," and fall into mourning, but it will not last long. Mentally, you have already healed. You have the strength to live the rest of your life.

Currently, in medicine, the understanding of concussion is that no abnormalities can be found on MRI. MRI itself is not a precise imaging tool, and the brain itself is an extremely delicate organ—any structural damage almost invariably leads to permanent functional decline. This means that if the damage is smaller than MRI’s resolution, it can still cause lifelong consequences.

Inside our brain, there are countless neurons that generate electrical signals. They are connected by axons, which transmit these signals. The axons are wrapped in myelin sheaths to accelerate signal transmission, and inside the axons are microtubules that transport nutrients to other parts of the cell.

Axonal tissue itself is viscous, meaning it can stretch to some extent. When external force is applied, different regions of the brain, having different masses, oscillate asynchronously. This asynchronous oscillation creates shear forces that damage the axons in between.

1. Mild axonal stretching

   This temporary stretching is called subconcussive impact and may cause no symptoms. The axons can later return to their original length.

2. Slightly more stretching

   At this stage, pores in the axon wall cause ion leakage, leading to an energy deficit in the brain and a variety of symptoms. Like the previous stage, the axons can return to their normal length, and once energy is restored, you recover completely. This is called transient dysfunction.

3. Stretch further than that

   From this point onward, we enter the realm of structural damage. Such damage is invisible on MRI, but on DTI (diffusion tensor imaging) you can see reduced FA (fractional anisotropy) and increased MD (mean diffusivity) and RD (radial diffusivity) in some white matter tracts. This happens because water molecules have left the axons. You will experience various symptoms chronically.

   Different axons may be in different states: some may be torn, some may have lost their myelin sheaths, some may be twisted. In clinical cases, these often coexist.

4. Stretch even further

   This leads to widespread axonal tearing. Glial cells, in order to protect the severed axons, act like band-aids, sealing off the damaged areas. At this point, the “band-aid” signal becomes visible on MRI. So finally, MRI can detect it.

According to statistics, 70% of concussion patients fall into categories 1 and 2. The remaining 30% go on to develop PCS (post-concussion syndrome). These PCS patients include those in categories 1 and 2 who also have other issues (e.g., neck or vestibular problems), plus all of category 3.

Therefore, for every PCS patient, undergoing DTI is crucial. The distinction between functional concussion and structural concussion determines whether you will fully recover or live with lifelong consequences.

目前医学界对脑震荡的理解是MRI上找不到异常。MRI本身并不是精确的成像工具，大脑本身也是一个极其脆弱的器官——任何结构性损伤几乎都会导致永久性的功能衰退。这意味着即使损伤小于MRI分辨率，仍可能带来终生后果。

在我们的大脑中，有无数神经元产生电信号。它们通过轴突连接，轴突传递这些信号。轴突被髓鞘包裹以加速信号传递，轴突内部有微管，负责将养分输送到细胞的其他部位。

轴突组织本身具有粘性，意味着它可以有一定程度的拉伸。当外部力量施加时，大脑不同区域因质量不同而异步振荡。这种异步振荡产生剪切力，损伤中间轴突。

1. 轻度轴突拉伸 这种暂时的拉伸称为亚震荡冲击，可能不会引起任何症状。轴突随后可以恢复到原来的长度。
2. 稍微多拉伸一些 此阶段，轴突壁孔隙会导致离子泄漏，导致大脑能量不足及多种症状。和前一阶段一样，轴突可以恢复正常长度，能量恢复后，你就能完全恢复。这被称为暂时性功能障碍。
3. 延伸得更远 从这里开始，我们进入了结构性损坏的领域。这种损伤在MRI上看不见，但在DTI（扩散张量成像）中，你可以看到部分白质束中FA（分数各向异性）降低，以及平均扩散率（MD）和径向扩散率（RD）增加。这是因为水分子离开了轴突。你会长期经历各种症状。 不同的轴突可能处于不同状态：有些可能撕裂，有些可能失去髓鞘，有些可能扭曲。在临床病例中，这些通常并存。
4. 进一步扩展 这导致广泛的轴突撕裂。胶质细胞为了保护被切断的轴突，就像创可贴一样，封闭受损区域。此时，“创可贴”信号在MRI上变得可见。所以，MRI终于能检测到它了。

根据统计，70%的脑震荡患者属于第一类和第二类。剩下的30%则发展为PCS（脑震荡后综合征）。这些PCS患者包括属于第1类和第2类且同时有其他问题（如颈部或前庭问题）的患者，以及所有第3类患者。

因此，对于每一位PCS患者来说，接受DTI至关重要。功能性脑震荡和结构性脑震荡的区别决定了你是能完全康复还是终身后果。

Generally speaking, if symptoms of a concussion still exist three months later, they are generally considered permanent. Optimistic doctors might say they can improve, but almost no doctor would say they can be fully cured and return to baseline. Because PCS itself means it is not a transient dysfunction, but rather structural damage exists. Precisely because scientists have discovered that the pathology of PCS is structural damage that cannot be seen on MRI, concussions are referred to as mild traumatic brain injury (mTBI) – “mild” implies microscopic.

You might see many concussion recovery channels on YouTube claiming that any concussion can be fully healed. I have to be honest: those channels are often trying to sell expensive courses. They aren't necessarily lying, because the definition of concussion is “after a blow to the head.” That blow can injure the neck or the vestibular system, and that is still a concussion. Those who claim concussion is treatable are usually treating the vestibular system or the neck, or teaching mindfulness to relieve anxiety. They have never actually addressed the real concussion itself – i.e., mild traumatic brain injury.

Once we understand the mechanism of structural damage, why does it lead to permanent inattention and fatigue?

The brain has a network called the Default Mode Network (DMN). It is responsible for thinking when we are not actively focusing attention. When you enter this mode, you might just be spacing out, not deliberately thinking, yet you still absorb all incoming information. In this state, your brain acts like a magnet, automatically drawn to the information – for example, when you read a newspaper, watch TV, a movie, or an animation. Almost all human cognitive activities rely on this mode. If you space out completely without any deliberate interference, you can even enter a state called “flow” – a state where the brain runs at extremely low energy consumption yet performs at peak efficiency.

What we commonly call “paying attention” essentially uses the DMN as well. However, this mode places extremely high demands on brain hardware. Anything like fatigue, insomnia, fever, or a cold can impair DMN performance.

The most terrifying thing about a concussion is that the key structures of the DMN – the corpus callosum and the cingulum – due to the shape of the brain, are most vulnerable to concussion. Shearing forces concentrate there. If that shearing force does not exceed the threshold, you experience only a performance drop due to an energy deficit – it feels like having a cold, not like losing something. But if you truly lose this ability, it means the damage has exceeded the threshold. The axons that participate in the DMN have already died. They may or may not be visible on MRI. Because the DMN has extremely high requirements for brain integrity, even damage that is invisible on MRI can impair it.

This damage is lifelong. You do not have “inattention” in the usual sense. Rather, the DMN you used to rely on is gone. You can no longer absorb information efficiently while spacing out; you just space out. You then mistakenly think you are distracted, so you force yourself to concentrate, using your prefrontal cortex to perform cognitive tasks. But this state cannot be sustained for long (and that is not your fault – no one can). So you feel that you cannot concentrate, and you try to extend this prefrontal cognitive effort. This actually forces the brain to run at an inefficient, high-energy mode, not the restorative, low-energy mode. Consequently, you cannot engage in long cognitive tasks and then feel refreshed as if after a nap; instead, you feel extreme fatigue, drowsiness, because your brain energy is depleted and you need sleep to recharge.

Much of our cognition happens under the DMN – for instance, experiencing nature. When you are bored, you space out, and in that spaced-out state you feel the environment around you. If the DMN is damaged, unless you deliberately look and observe carefully, you will not generate any effective information, even if you are in your favorite environment. Moreover, the experience of the executive network (manual focused attention) is different from the DMN. That is why after a concussion, your perception, sensation, feeling, and experience change.

It is like driving a long-distance car. The car has both autopilot and manual driving modes. Normally, you spend most of your time in autopilot, switching to manual only for special tasks. But if autopilot fails, you either drive manually the whole way and become extremely fatigued, or the car stops moving altogether. And you will feel that this is no longer the same driving experience – a part of you (the autopilot) is gone.

I know many people are most concerned about treatment. I am sorry to say that brain cells cannot regenerate. Any structural damage, from mild to severe, is permanent. If you had any chance of full recovery, it would not have become persistent post-concussion syndrome. That means you already have a permanent structural deficit, and that deficit has caused the DMN to disappear forever.

What you can do is use cognitive strategies. For example, notebooks, voice recordings, etc., to replace that autopilot. Then use those notes or recordings to find the information you need for work.

Alternatively, you can maximize the duration of manual driving through exercise, medication, and effective rest. This approach is called brain compensation – using other brain regions to take over the lost function. Over time, with compensation, your manual driving ability can become stronger, from getting tired after 20 minutes to lasting two hours.

Using both methods together can help you return to society and find a job. Doctors only address your ability to return to society. If you are already working, then you are considered a completely normal person, and your family and friends may think so too. Thus, this injury is invisible. It shows up in your personal abilities and quality of life. But you must be clear: you indeed have a brain injury. Do not think you are not trying hard enough just because others see no difference between you and a normal person

一般来说，如果三个月后脑震荡症状仍然存在，通常被视为永久性的。乐观的医生可能会说他们可以改善，但几乎没有医生会说他们能完全治愈并恢复到基线。因为PCS本身意味着它不是短暂的功能障碍，而是结构性损伤的存在。正因为科学家发现PCS的病理是MRI无法观察的结构性损伤，脑震荡被称为轻度创伤性脑损伤（mTBI）——“轻度”意味着显微镜下损伤。

你可能会在YouTube上看到很多脑震荡康复频道声称任何脑震荡都可以完全愈合。说实话：那些频道往往是在推销昂贵的课程。他们不一定是在撒谎，因为脑震荡的定义是“头部受击后”。这种打击可能会损伤颈部或前庭系统，这仍然是脑震荡。那些声称脑震荡可以治疗的人，通常是在治疗前庭系统或颈部，或者教授正念以缓解焦虑。他们从未真正处理过真正的脑震荡本身——也就是轻微的创伤性脑损伤。

一旦我们理解了结构损伤的机制，为什么会导致永久性的注意力不集中和疲劳？

大脑有一个称为默认模式网络（DMN）的网络。它负责在我们不主动集中注意力时思考。进入这个模式时，你可能只是走神，没有刻意思考，但你仍然吸收了所有输入的信息。在这种状态下，你的大脑像磁铁一样，自动被信息吸引——例如，当你读报纸、看电视、看电影或看动画时。几乎所有人类认知活动都依赖于这种模式。如果你完全空闲，没有任何有意干扰，你甚至可以进入一种叫做“心流”的状态——大脑以极低的能量消耗运行，却能发挥最佳效率。

我们通常所说的“关注”其实也用到了DMN。然而，这种模式对大脑硬件的要求极高。任何像疲劳、失眠、发烧或感冒这样的情况都会影响DMN的表现。

脑震荡最令人恐惧的是，由于大脑形状，DMN的关键结构——胼胝体和扣带——最容易受到脑震荡的影响。剪切力集中在那里。如果剪切力没有超过阈值，你只会因能量不足而表现下降——感觉就像感冒，而不是失去什么东西。但如果你真的失去了这个能力，说明伤害已经超过了阈值。参与DMN的轴突已经死亡。MRI上可能看不到。由于DMN对大脑完整性有极高的要求，即使是MRI上看不见的损伤也可能损害大脑。

这种损伤是终身的。你并不是通常意义上的“注意力不集中”。相反，你曾经依赖的DMN已经消失了。你无法在恍惚时高效吸收信息;你只是走神。你会误以为自己分心了，于是强迫自己集中注意力，用前额叶皮层执行认知任务。但这种状态无法持续太久（这不是你的错——没人能）。所以你觉得自己无法集中注意力，试图延长这种前额叶的认知努力。这实际上迫使大脑处于低效的高能量模式，而非恢复性低能量模式。因此，你无法进行长时间的认知任务后像小睡后那样感到精神焕发;相反，你会感到极度疲劳和嗜睡，因为大脑能量耗尽，需要睡眠来充电。

我们的大部分认知都发生在DMN之下——比如体验大自然。当你感到无聊时，你会走神，在那种恍惚状态下你感受到周围的环境。如果DMN受损，除非你有意识地仔细观察和观察，否则你无法产生任何有效的信息，即使你身处你喜欢的环境中。此外，执行网络（手动聚焦注意力）的体验与DMN不同。这就是为什么脑震荡后，你的感知、感觉、感觉和体验会发生变化。

这就像开长途汽车。汽车既有自动驾驶模式，也有手动驾驶模式。通常你大部分时间都在自动驾驶，只有在特殊任务时才切换到手动模式。但如果自动驾驶失效，你要么全程手动驾驶，感到极度疲劳，要么车辆完全停止移动。你会感觉这已经不再是同一种驾驶体验——你的一部分（自动驾驶）消失了。

我知道很多人最关心的是治疗。很遗憾地说，脑细胞无法再生。任何结构性损伤，从轻微到严重，都是永久性的。如果你有机会完全康复，就不会变成持续性的脑震荡后综合症。这意味着你已经有永久性的结构缺陷，而这种缺陷导致DMN永久消失。

你可以用认知策略。比如笔记本、语音录音等，替代这种自动驾驶。然后用这些笔记或录音找到工作所需的信息。

或者，你可以通过锻炼、服药和有效休息来最大化手动驾驶的时间。这种方法称为大脑补偿——利用其他脑区来接替失去的功能。随着时间推移，通过补偿，你的手动驾驶能力可以增强，从20分钟后疲劳到持续两小时。

结合这两种方法可以帮助你重返社会并找到工作。医生只关注你重返社会的能力。如果你已经在工作，那么你就被视为完全正常的人，你的家人和朋友也可能这么认为。因此，这种伤害是看不见的。它体现在你的个人能力和生活质量上。但你必须明确：你确实有脑损伤。不要因为别人看不出你和普通人有什么不同，就觉得自己不够努力

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:

• 头皮：如果头皮吸收了大部分力量，就会导致皮下血肿（“鸡卵”）。
• 头骨：我们的头骨异常坚硬。虽然通常具有弹性，但颅骨与大脑之间的液体会产生“回声效应”，导致短暂的眩晕（通常不到30秒）。如果力超过颅骨阈值，就会发生骨折，残余能量直接传递到大脑，导致开放性创伤性脑损伤（TBI）。
• 颈部：如果颈部吸收了力量，可能会干扰脑部血流。我们大脑的能量供应依赖于颈部的血管;这里的伤势会模拟脑震荡症状，导致代谢危机。
• 前庭系统：这是眼睛与大脑之间的神经连接。这里的损伤会导致头晕和光敏感。
• “隐形”损伤：虽然头皮和颅骨损伤可见，但颈部和前庭问题往往“隐形”。许多脑震荡诊所成功治疗这些“隐形”伤害。然而，如果力量绕过这些过滤器，直接被大脑吸收——症状出现——真正的脑震荡就是从这里开始的。

2. 震荡的本质：布线与结构损伤

大脑的一致性类似豆腐，由神经元组成，这些神经元由庞大的“蜘蛛网”轴突——长而细的纤维——连接在一起。电信号沿着这些轴突内的水分子传播，这些轴突被紧密包裹以确保信号完整性。

• 能源危机：撞击时，轴突被拉伸和压缩。这种暂时的拉伸会导致水分子泄漏并与细胞外环境交换。这种“泄漏”会造成暂时的能量间隙。随着大脑补充能量储备，这一缺口通常会自动消除。
• 弥漫性轴突损伤（DAI）：由于大脑是一个统一的器官，撞击会引起“弥漫性轴突损伤”——几乎所有区域都会经历某种程度的轴突拉伸。物理学表明，通常存在一个“应力点”，力集中度最高，导致特定症状。允许完全恢复的细微拉伸通常被称为“亚脑震荡”。
• “新常态”：如果撞击速度较快，应力点会受到轴突、微管和髓鞘的严重损伤。胶质细胞会迅速修复这些区域，这一过程通常在三个月内结束。如果症状持续超过该时间窗口，则被归类为脑震荡后综合征（PCS）。
• 结构性现实：PCS本质上是一种结构性损伤。轴突剪切、微骨折或髓鞘流失意味着大脑永远无法恢复到“出厂设置”。胼胝体和腹环束是最常见的应力点;这里的损伤不可避免地导致认知和人格的变化。这就是“新常态”。

3. 治疗：残酷的真相

围绕“脑震荡治疗”的混淆源于定义过于宽泛。

• 1型（非结构性）：如果你没有结构性损伤，且症状源自颈部或前庭问题，可以通过治疗这些部位来“恢复”。
• 第二型（结构性）：真正的PCS——伴有结构性变化的轻度创伤性脑损伤——无法以传统意义“治愈”。这是终生的改变。
• 康复的作用：现代研究表明，受控运动（而非完全休息）通过分泌神经突触物质有助于胶质细胞。然而，认知训练的重点是优化，而非恢复。它帮助残疾人重返工作岗位，但无法让你恢复到“原来的自己”。如果硬件被修改，“原始你”将成为封闭的章节。

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.