Each  phrase on this small page has an individual page on our larger website Hersenletsel-uitleg.nl.
Parts of this Dutch site have been translated into English (Brain Injury Explanation). This small page, is a summary of the possible effects of a brain injury, and an introduction to sensory overload
A list of the possible consequences of brain injury per specific area of the brain is available on main website!

Use a translation computer to read everything on the Dutch site!
(See this link) ...



A brain injury is unique to the individual, no two brain injuries are exactly alike !

The consequences are different for everyone. Some people may only have one complaint, others more. How the injury manifests can also vary greatly. There is often a combination of injury and residual skills, remaining knowledge and understanding (intelligence), thinking ability (cognition), behavior and personality,
which is very individual.


1. Brain damage - general information - consequences


Different types of complaints may occur after brain injury. These complaints can be very different in nature. Each brain injury is different.

The symptoms that occur depend on various factors, such as what caused the brain damage, where the injury is located in the brain and the severity of the injury. Factors such as age and a person's social situation may also play a role. It is sometimes difficult to predict when and why someone will experience certain symptoms and how long they will continue. Brain damage cannot even always be made visible seen with brain scans.

Several of the consequences of a brain injury are only visible after a while. People may have sometimes tried to continue to maintain their life as they know it (to survive!) for a very long time before the link was made with a head injury that someone had previously suffered.
 Some people fight so long and hard to keep things as they were, that it literally becomes a fight for survival
Unfortunately, nobody gets a manual with their brain injury to explain what (sometimes invisible) consequences they will experience, or how to deal with them. 

Often, people overestimate themselves until they reach a better understanding of the consequences of their brain damage. It is when people have tried to return to their previous way of life that they experience the (invisible) consequences and find themselves floundering. This is when they may start to research the subject themselves and/or seek professional help.

There is no route map, no GPS in your new life with your brain injury. It seems like a big jig saw puzzle that you have to put together to discover  your new 2.0 version.

2  Mobility: Being (un)able to perform, coordinate and plan movements.

  • Half-sided paralysis (left or right sided).
    The paralysis is on the other side of the body than where the brain injury occurred (with the exception of the cerebellum).
    Each half of the greater brain (cerebral hemisphere) controls the body half on the other side. This is called contralateral.
    The left side of the cerebellum controls the left half of the body, and conversely, the right side controls the right half of the body. This is called ipsilateral.
  • Loss of strength (hemiparesis)
  • Cramps in limbs
  • Spasticity
  • Motion disorders (motor inertia, impossibility to move, coordination and balance problems)
  • Proprioception disorder (sense of position - how your body or body part is relative to the environment)
  • Ataxia - Coordination disorder
  • Apraxia; difficulties in planning and carrying out movements
  • Dysphagia; Swallowing disorder

3. Sensory disorders: These are complaints that affect vision, hearing, touch, taste and smell.

  • Amplified hearing; hyperacusis (not to be confused with over-stimulation of the senses) ánd sensory overload of sound. (see 9.)
  • Temperature disorders; Someone can no longer feel the difference between hot or cold. Body temperature can no longer be properly controlled or there is heat intolerance.
  • Tactile disturbances (touch and sensory sense).
  • Neglect; reduced or absent attention to sensory impressions (typically, one is not conscious of the left side of the body - mostly occurring after brain damage to the right side). Neglect (hemi spatial neglect): someone does not perceive body parts on one side of the body, for example is unaware of space and objects on the left side.
  • Agnosia; difficulty recognising/ to recognize faces or recognising / recognize objects or sounds.
  • Sensory overload, Over-stimulation of the senses / sensory information processing disorder after brain damage / overreact to sensory impressions (see 9.)
  • Sudden deafness
  • Visual consequences for brain damage:
    • Hemianopia; loss of field of view.
    • Cerebral visual impairment (CVI) - is a brain disorder not an eye disorder; vision can be alternately sharp or unfocussed. The eyes are able to see, but the brain is not interpreting what is being seen
    • Prosopagnosia; not recognizing faces.

4. Communication disorders

Problems with communication  can manifest in many different ways. For example, some people have difficulty speaking and wording while others have difficulty understanding the language. Cognitive issues such as "delayed information processing" can also cause communication problems. For example, it can be difficult to follow someone who speaks very quickly or changes subject frequently.

* Aphasia - difficulty understanding and producing language ie speaking.
* Dysarthria - articulation disorders.
* Speech apraxia - is a form of movement disorder: difficulty in using the muscles of the mouth and jaws. One is unable to perform purposeful movements despite proper coordination and muscle power.
* Difficulties with understanding language literally. They don't understand sarcasm, irony, or humor, but see it in pictures literally.
* Being easily distracted or unable to remember what someone else is saying.
* Fatigue. One can be too tired to store and interpret information.
* Finding it difficult to function in a busy environment
* Not able to notice intonation differences interpret feelings and understand nuances or not being able to show one’s own emotions.
* Deafness due to brain damage.
* Delay or difficulties switching from one topic to another. An example of this is an unexpected phone call, It is difficult to turn one’s attention from one's own thoughts to the caller. Many people with brain damage therefore find that unexpected telephone calls are unpleasant.

5. Cognitive consequences

With cognition we indicate the processes that are needed to be able to think. Cognition consists of many different functions. Some examples are remembering information, learning abilities and maintaining one’s attention. We need cognitive functions in almost everything we do in our daily lives.

* Memory impairment
* Attention and concentration difficulties
* Executive dysfunctions examples are difficulties with planning, working memory, emotional regulation, maintaining awareness
* Neglect (hemispatial neglect) someone does not perceive body parts on one side of the body, is unaware of space and objects on the left side. (Mostly with braindamage on the right hemisphere).
* Disorientation; changed awareness of person, time and/or place
* Prosopagnosia; no longer able to recognize (recognise) faces
* Changed consciousness of the passing of time; not being able to estimate time correctly or not knowing which part of the day it is. When making plans experiencing difficulty with judging the amount of time necessary for an activity.
* Delayed information processing
* Extreme persevering; unable to stop a thought, action, movement, talk about a subject, hobby or getting stuck in a particular feeling.
* Language problems (see also communication).
* Over-stimulation can also manifest itself at the cognitive level. However, it is a neurological (sensory) consequence of brain damage.

6. Emotional consequences:

(NOTE: Some only have one complaint, others are more.) Emotional changes, on the one hand, can be a direct consequence of brain damage, but also emotional issues are caused by the traumatic effect of brain damage. No two brain injuries are alike! The emotional effect of experiencing limitations due to brain damage can also contribute to changes in emotions. Not every brain-damaged person changes his character negatively. Some people with injuries become milder, softer. (NOTE: people can experience one or more emotional issues)

* Apathy (reduction of initiative)
* Irritability (irritation / losing one’s temper / aggression)
* Mood swings, the risk of depression is increased in people with brain damage. Sadness is also common.
* Behavior without inhibitions / impulsivity
* Risk-seeking behavior
* Decorum reduction; no longer being able to judge if something is appropriate to say
* Libido changes
* involuntary crying and/or
laughing Pseudobulbar affect (PBA)
* Easily moved to tears
* Increased emotional sensitivity, faster emotional
* Milder personal traits than before the injury, easy going, friendlier
* Forthright
* Less empathy

* Changed sense of humour or someone having trouble understanding sarcasm or irony. Taking language literally.
* Difficulties how putting things into perspective
* Impaired insight into illness / Unrealistic expectations 
* Egocentricity
* Changes in personality
* Post traumatic stress disorder
* Reduced ability to cope with stress
* Changed desired for intimacy /experience of sexuality
* Changed relationships with people
* Changed friendships

7. Other physical disorders:

Sometimes, brain damage results in the development of other specific physical disorders. Below are a number of complaints that can occur after brain injury:
* Epilepsy
* Coma and lowered consciousness
* High brain pressure, brain edema
* Sleep disorders (eg insomnia, too much need for sleep, apnea caused by brain damage)
* Disorders of bladder and intestinal function (incontinence)
* Swallowing disorder (dysphagia)
* Headache

8. In general:

Sometimes the complaints that are experienced cannot be classified as physical, mental or other, and cannot be accurately categorized. These complaints can indirectly affect many of the specific features mentioned above and are therefore of great importance to a person's daily life.

* Fatigue / neuro fatigue
* Sensory overload / over-stimulation of senses and of cognition due to too much information / incentives.
We have found traces of the origin of overstimulation and recorded this in a study to be published.

Remember: No two brain injuries are alike !

9. Hypersensitivity / Over-stimulation / *Sensory information processing disorder as a result of brain injury* / Overreacting to sensory impressions / Unusual sensory processing * (help us with good translation, thank you!)

Sensory overstimulation is a debilitating situation that has a neurological origin. It occurs when more information (in the form of stimuli) is received by the brain than the brain is capable of processing. The brain cannot properly filter environmental stimuli or does not allow them to pass through the necessary neural pathways at a sufficient speed. A stimulus is information that we receive through our senses; to see, hear, smell, taste, feel (external stimuli) or through our thoughts or our body (internal stimuli).

Also, proprioception or one’s sense of position or relation to the environment can be overwhelmed and overstimulated *. Proprioception is the ability to perceive the position of our own body and body parts. It seems that this information from various sensory cells can also over-stimulate the brain. People then indicate that they feel seasick or  'drunk', as if their balance is disturbed.

Over-stimulation is one of the most common complaints after brain injury. The senses provide more information than can be adequately processed by the brain and this can lead to physical feelings of unwellness.

Although over-stimulation occurs frequently, many patients find it difficult to find recognition and understanding of over-stimulation and its effects from doctors, family, friends, and at work.

There are various names for the problem of sensory overstimulation.

Overloading of neural networks, flooding of the senses or sensory overload are some of them. Every single name points out a serious and underestimated problem. It is a chronic and invisible result of brain damage. Not comparable to hyperacusis. Although it does happen that hyperacusis occurs at the same time as sensory overload. Sometimes there are multiple forms of sensory overstimulation happening at the same time.


Sensory overstimulation is as well as a a consequence, also actually a condition in itself. In the case of brain damage, something has been permanently damaged in the brain. If, two years after the brain injury, the symptoms of sensory overload have not diminished, the unfortunate prognosis is that one should learn to live with it ... [* source: our questionnaires; consider this as copyright]

The 7 senses that can be overstimulated are:

    The visual sense (sense of sight)
    The auditory sense (hearing sense)
    The olfactory sensation (sense of smell)
    The gustatory sense (taste sense)
    The vestibular sense (labyrinth and equilibrium sense)
    The tactile sense (touch and feel)
    The proprioceptive sense (the muscular sense, the kinesthetic sense ('the sense of movement')).

Normally, all these stimuli are processed properly by our brains. We call this capacity of the brain "mental capacity." After brain damage, processing of stimuli is often disturbed, (sensory hypersensitivity) and sensory and cognitive overload occur.
This can result in unpleasant complaints and recovery from these complaints can be difficult and slow  each time a person is overloaded *. Read more about fatigue or neuro fatigue on our website. [* source: our questionnaires; consider this as copyright]

Where in the brain?

The brain structures involved in overstimulation are all neural structures that recognise and then process a stimulus of being aware stimulus. That is, from start station to end station.
The amygdala, brain stem, pituitary and thalamus are most often associated with the treatment of stimuli, because these structures receive, filter and encode the stimuli in importance, but also the cerebral cortex of the frontal lobe and neurotransmitters play a role in attenuating stimuli in healthy (healthy) brains.

What are the complaints that are caused by over-stimulation?
What are the symptoms caused by caused by overstimulation
What we found in the results of our study (2016):

  • Overstimulation complaints vary from mild irritation to headache * pain in the eyes *, ears * and skin *, nausea *, vomiting*, exhaustion * up to and including temporary paralysis symptoms *. In short: an overloaded system and a source of stress * can mean physical illness *.

  • Many people have to reduce their social contacts and become isolated *. Life in isolation is the only way to prevent over-stimulation *.


  • Many patients with brain injury are in constant depletion mode due to chronic over-stimulation *, which can hardly or not be trained * Learning  rest and pause strategies can help to understand and have a measure of control over this, but does not offer a cure*.


  • Temporary exacerbation of, for example, paralysis of the affected side *, for example, in the face *, arm * or leg * and failing speech * is common.

  • People have died due to chronic fatigue caused by overstimulation *. Overstimulation should not be underestimated!

NOTE! Several complaints have been discovered by us, our results are available for scientific research. [* source: our questionnaires consider this copyright]


4. Three categories of overstimulation

What we found in the results of our survey (2016):

  • The form in which the limit is immediately exceeded. For example background noise can result in immediate overstimulation*.
  • The form in which stimuli accumulate (like a traffic jam) and at a certain instant they can no longer be processed. Then there is overstimulation*.
    For example: someone perseveres for ten minutes in a company of people but then it becomes too much. This person should prevent this from happening by leaving the company of people within those ten minutes before they reach their limit.
  • Delayed overstimulation by hyper focus *. When people train or force themselves knowingly and willingly 'to be able to do something', the overstimulation can strike after completion of the task, and strike mercilessly. In this case, training has adverse effects*.

[* source: our questionnaires consider this as copyright]



5. How can we recognize overstimulation?

What we found in the results of our survey (2016):


In our survey, people indicated that symptoms of overstimulation vary per person*, per situation* and per moment*. This sometimes makes it difficult to recognise overstimulation for both the environment and for the person involved*. Overstimulation fluctuates from day to day, for example, if the overload is already in place, it gets worse. * and the trigger for overstimulation differs *.

The following problems are mentioned in our survey:

- Extreme (sudden) fatigue that requires a long recovery*
- Headache*
- A feeling as if there is a tight band around the head*
- Pressure in the head*
- No longer able to participate in a conversation*
- Word finding problems, these pass once the overstimulation is over* Difficulty gettingt he words in your head out of your mouth, or word-catching problems (hearing something different, or incoherently) this too passes if the overstimulation is over

- Faltering speech that passes once the overstimulation is over*
- Reduced articulation*
- Difficulty and slowness in thinking*
- Reduced concentration*
- Reduced coordination of movements*

- Contact avoiding behaviour because there is an 'overload' in the head*
- Looking away and not being able to take part in the conversation in order to protect themselves from the stimuli*

- Irritation, aggressive behaviour, being short tempered, irritable , having a short fuse*
- Being more emotional*
- Hyperactivity, increased activity, being busy*
- Crying, fatigue crying*
- Being scared*
- Increased heart rate, higher breathing or restrained breath*
- Shaking, stiffening of the muscles, chance of falling over*
- Blinking or closed eyes*

- Nausea or vomiting*
- Temporary loss of facial muscles*
- Numbness of the affected side / reduced motor skills*
- Short absences of consciousness*
- Totally exhausted feeling*


"It’s very chaotic, or busy in my head, behind my eyes.  I am extremely tired. It seems as if my head can burst open at any moment. I often get sick, my thinking falters and I just feel totalled." one of the respondents stated.

It is important to keep in mind that overstimulation differs per person.*

[* source: our questionnaires consider this as copyright]



6. Different forms of overstimulation

What we found in the results of our survey (2016):

  1. Cognitive overstimulation*
  2. Sensory overstimulation (sounds, image, light, smell, feeling / sense of touch, position sense)*
  3. Emotional overstimulation*


Cognitive overstimulation

Cognitive overstimulation is caused by:

  • Own thoughts*
  • Multitude of what is said or being asked for*
  • Multitude of information to be processed, for example duplicate tasks or multitasking. Often, people with brain injury cannot do two things at the same time. It is either the one or the other. For example listening and working on something at the same time does not go well*.
  • Often information processing is delayed in case of brain injury, as a result of which stimuli can accumulate*.

This can lead to a situation in which the seriousness of the overstimulation is underestimated by healthcare professionals who are insufficiently trained to be alert to this.

Sensory overstimulation

is caused by:


Overstimulation by sound due to the inability to filter out background noise occurs, making it difficult to have a conversation.

In our survey we heard about: sound intolerance to music*, high or low tones*, child voices*, high ladies voices*, cutlery sounds*, teaspoons stirring in a glass* and the like. Also irritation with rhythmic sounds*, such as tapping a pen occurs*.

Many complaints are reminiscent of or are similar to hyperacusis, in which sound is often perceived as being too loud, maddening or hurting the ears.


  • VISION sense / eyesight

Visual overstimulation occurs while seeing busy patterns* or colors (USA) colours (UK)*, a multitude of objects in the house*, a piece of text without enough spacing in between the lines, and *, seeing movements*. See also the page vision problems.


  •  LIGHT

Overstimulation due to light occurs, for example, in light reflection*, in certain light bulbs (halogen / tl)*, backlighting* or changes in shadow*. Notorious are the car rides on a road with lots of trees and a low sun behind the trees*.



Overstimulation of tactile feeling occurs in people who suffer from extreme sensitivity to  movement*, touch*, vibrations*, bass tones*, etc. Sometimes this overstimulation is experienced as pain through touch*, physical pain.



We observe the position of our body throughout the day and how our body relates to the world around us. In every muscle, joint and connective tissue there are minuscule sensors (proprioceptors) that let us know how we stand, sit or lie. In people with brain injury this multitude of information can be experienced as feeling dizzy* or unsteady on the legs*. One can become  overstimulated by things such as movement*and position of your head*, this leads to feelings of uncertainty about how to navigate your body*.



Overstimulation by odours can be caused by the enhanced smell of food smells, natural scents, body odours, perfumes and deodorants*.



Nociception (feeling pain) and thermoception (feeling warmth and cold) are also senses that can over stimulate. Those who have a lot of headaches for example are more likely to be overburdened with sensations  and therefore over-stimulated*.


Emotional overstimulation

In itself, it is questionable whether emotional overstimulation is part of cognitive overstimulation.

Emotional overstimulation has to do with the increased emotional vulnerability after brain injury*. Once overstimulated, the person can often no longer regulate the emotions*. The reactions are often more emotionally extreme and that can vary from person to person from fatigue-crying to 'being more concerned with someone else*', frustration (also to oneself), being angry or aggression.

In emotional situations in someone's life, the 'measuring cup' appears to fill up quickly and sensory stimuli are less well tolerated.


Crying often gives relief. For people with overstimulation, it does not necessarily have anything to do with sadness*. It should not be confused with compulsive crying or with emotional lability.


Overstimulation can not always be prevented. Some people experience emotional overstimulation in which their own thoughts are experienced as overwhelming. The same applies to empathising and sympathizing with another.


Overstimulation functions in three directions. Through our bodily sensations, tho through our thoughts and emotions which are harder to control if too many stimuli are perceived* and stimuli pile up*. If someone is already overstimulated, the cognitive "inbox" becomes full.*

[* source: our questionnaires consider this as copyright]


7. Congestion of stimuli


If more stimuli are received than the brain can handle, , the stimuli begin to pile up, meaning that there are still a lot of (unprocessed) stimuli in the traffic jam.
Compare it with just as much traffic on a normal four-lane highway that suddenly has to use a country road ... including honking and light signals from the motorists who do not want to stand still!

Your nervous system is constantly busy working with the processing of all incoming 'info' of sound, image, smell, movement, feeling, thoughts or listening to everything that is said all the other sensations that are a normal part of the lives we live. People with brain injury can have big problems with processing stimuli. They can become very ill by simply processing normal information.



8. Medical background of overstimulation

Overstimulation can be caused by

  • Broken filtering

All stimuli enter the brain as equals, both the important and the unimportant stimuli. They are not filtered. The stimuli arrive unrestrained in the brain. The brainstem, the thalamus and the cerebral cortex (frontal) and the neurotransmitters should process the information, judge it’s relevance and then inhibit the less important information. Specific damage in an area can disrupt the filter or destroy it completely.


  • Diversion = delay

When a brain injury causes brain cell activity needed to process information to be re-routed around the injury, there is a delay in perception. This is not only when there is a focal, local injury, but also in the case of diffuse injury, spread over the brain. It takes longer before stimuli are interpreted. That is one of the causes that make a person with brain damage being overwhelmed by stimuli. This is also called delayed information processing.

There are more stimuli on hold than can be processed. Just like a PC that crashes because the processor is too slow.


  • Fragmented observation

Many people with overstimulation due to brain injury observe every separate detail through hyper selection. For these people it is difficult to see connections between details and to see / view / listen to the whole.

This can be the case both on the auditory and on the visual level. As long as one sound stimulus is offered, the conversation is central and there is no music playing in the background, there is no problem with noise. But if there is a buzz in the background or more obtrusive background noise, then the processing of the stimuli goes wrong.

This can also happen in the visual area. People cannot ignore details, every drop on the windshield of the car when it rains and the action of the windshield wiper, or every individual in a group, or every stone on a cobblestone road.


  • Distorted processing can cause overstimulation
    • Cerebral visual disorders CVI - double vision, varying sharp vision, depths can become immense or not, spaces can be observed as larger or smaller than they actually are
    • Agnosia - not recognizing an object, sound, smell, etc.
    • Non synchronous processing of stimuli in the brain. Signals do not arrive synchronously at the brain area.



9. Summary of consequences of overstimulation *
What we found in the results of our survey (2016):

  • No longer being able to think*
  • Fight-flight or stiffen reaction*
  • Extreme fatigue*
  • Vicious cycle of fatigue to prolonged exhaustion*
  • People have died from exhaustion due to long-term accumulation of overstimulation*
  • Physical complaints due to high stress hormone by prolonged stress due to overstimulation*, chance of nervous system change, autoimmune disorders, cardiovascular disease, muscle function change, disturbance of sleep and sleep problems, depression, burn-out or anxiety disorders.

[* source: our questionnaires consider this as copyright]



10. Project flooding

We established Project flooding as a patient interest organization. We hope to achieve a society, where physicians and media take this target group seriously and to create a network that we can use to develop relevant products but also for further scientific research.

We encourage scientific research into overstimulation.
We are a recognised patient interest organisation for overstimulation as a result of brain injury since 2016.

In 2019, we received the Gold medal of honor for particularly good work for people with brain injuries.

11. Videos on overstimulation

We have created a special page (see link) with videos on different types of overstimulation.

12. Do you want to help?

Would you like to make a better translation than the one that we have attempted here?
Would you like to help us promote the cause of overstimulation as a result of brain damage in your country ?

Please contact us and help us with a good translation. Thanks!! We do not trust the translation of the words "overstimulation" and "stimuli / incentives" are correct. Maybe you are thinking "YES! It's not called overstimulation but ..." Tell us :)

We work voluntarily without pay but with heart for brain damage.

If you see an error ... Please email us the paragraph with the corresponding number, then the entire sentence that contained the error - in black - and then make the corrected sentence green. Then we can easily find the wrong sentence. :)