Dyscalculia is a math learning disability that impairs an individual's ability to learn number-related concepts, perform accurate math calculations and perform other basic math skills.

Difficulty with arithmetic, numbers, sequences of numbers or quantities is not a consequence of brain damage that will be noticed first.
It can cause significant problems in daily life, especially in our digital world.


Dyscalculia or acalculia

There are different views on how an arithmetic disorder should be called if it is a consequence of a neurological injury such as brain damage. Both the terms 'dyscalculia' and 'acalculia' are used.

On this page we want to discuss the difficulties and problems that people with brain damage experience with arithmetic,
numbers, quantities or amounts. They did not have those problems before the injury.
We do not discuss the learning or developmental disability. The symptoms may very well be the same, but the underlying causes and
intervention strategies are different.



Dyscalculia after brain injury can vary from mild complaints that are barely noticeable to significant problems in daily life.

For example, consider the difficulty that can arise if digital access codes are required, sent to a mobile phone, and a person has difficulty seeing or putting these numbers in the correct order.

Dyscalculia can co-occur with dyslexia during normal intellectual functioning and is related to it. It is also related to spatial orientation problems. Dyscalculia can be a sign of early dementia if no other brain injury has occurred.


Examples of problems in daily life

Attention! Not all of the problems mentioned need to occur in one person. One person with a brain injury may experience one or two complaints from this list, while another may experience five.
Most people with dyscalculia after brain injury have problems estimating quantities. Is it less or more, too much or too little?
There may be problems with counting. The person uses the fingers to count
There is difficulty solving a calculation. Difficulty remembering the numbers used to make the calculation. Difficulty visualizing the sum and retaining it in working memory of a sub-task. For example, with the sum 3 x 27 one must first remember the subtask 3 x 20, and then think of 3 x 7 and add the two results, 60 and 21.

There may be problems with the order, putting numbers or digits in order, reading recipes or telling the time. In case one has difficulty with digital numbers, 1:30 PM can be read as half one, which would lead to the incorrect conclusion that it is half past twelve. 2:30 PM can be read as half two, which would lead to the incorrect conclusion that it is half past one. In case one cannot recognize numbers, analogue telling of the time is also difficult and a speaking clock or alarm clock can help.


There may be problems with spatial orientation (math operations or reading a map). Interpreting codes and patterns (musical notes or languages) can cause problems.
People may have difficulty entering the correct PIN codes, number codes, series of numbers or remembering them.
There may be problems with mental arithmetic or with the calculation rules, or with checking how someone has calculated something to pay together.
There may be difficulty handling coins or finding the right amount in the wallet at a cash register.
There are menus that frustrate people. Without the ability to operate a menu (with numbers!), some people cannot operate their heater, thermostat or printer, let alone get the right employees on the phone. In an emergency, not even the doctor's office. And when they get on the phone with the latter, they have to call their personal number, which can look like abracadabra to someone with dyscalculia.
Someone with dyscalculia may even have difficulty identifying the correct dice in a game.

If someone has difficulty quickly estimating the numbers on the dice, especially if they are close together, crowding may occur. A kind of visual form of overstimulation. It then becomes impossible to observe the dots separately.


Three main forms of dyscalculia

Three main forms of dyscalculia are distinguished:

  • Aphasic dyscalculia
    There are problems reading (alexia) and writing (agraphia) numbers.


  • Spatial dyscalculia
    Arithmetic errors occur due to misplacement of numbers and misalignment of columns. This type of dyscalculia is usually associated with damage to the right hemisphere of the brain. Especially if there is also unilateral spatial neglect on the left, and
    constructive apraxia (for example, someone cannot draw properly or construct simple figures / put something together).


  • Anaritmetry
    A math disorder in which a person no longer knows how to divide or multiply and has forgotten the rules.
    The anarithmetry is not explained by aphasia, apraxia, alexia or spatial disturbance. It most commonly occurs after an injury to the left parietal lobe. It is one of the four characteristics of 'Gerstmann's syndrome'. (later on this page).


Underlying neuropsychological problems

There can be several causes that can influence the problem of dyscalculia:

  • Not being able to visualize figures and figures well
  • Less good/not reading and recognizing numerical symbols
  • Difficulty with logical reasoning
  • Difficulty with abstract thinking
  • Delayed information processing
  • Problem with working memory
  • Problem with attention processes
  • The lack of concentration
  • The lack of overview
  • Crowding problem: a visual form of overstimulation. Crowding is the phenomenon in which someone can no longer perceive visual stimuli that are close to each other separately.
  • Having trouble writing
  • Less understanding of verbal instructions
  • Decreased activity in the brain areas where word recognition and word analysis take place

Neuropsychological examination

It may be important for a neuropsychologist to find out which of the forms of dyscalculia is involved and which possible underlying neuropsychological processes are affected by the inability to calculate.


During a neuropsychological examination, the skills and the brain areas associated with the skills will be examined. Various tests will be administered that will be interpreted in conjunction with each other. In this way something can be said about the consequences of the brain injury. It is checked whether the applied skill is appropriate for what one can normally expect at an age.

It is important to see if there are problems both verbally and in writing. If a person has lost the understanding of numbers, it can be confused with aphasia. Working memory plays a role in remembering and repeating sequences of numbers, such as telephone numbers.

The following is evaluated:

  • Intellectual functioning
  • Visual-spatial skills
  • Memory and orientation
  • Language and speech skills
  • Mental arithmetic skills (number sequence with forward and backward counting, reading aloud and dictating simple and multi-digit numbers, single-digit arithmetic, etc.)
  • Written mathematics and sequential operations
  • Interpretation of mathematical symbols
  • Arranging numbers in columns


Where in the brain?

As we wrote earlier, the underlying neuropsychological problems of difficulties with numbers, figures, symbols, quantities, etc. have to do with specific brain areas that are needed for a task.
However, there are also specific areas of the brain that have everything to do with arithmetic:


Parietal lobe

In healthy brains, a fronto-parietal arithmetic network is active during arithmetic. This concerns both the prefrontal cortex (in the forehead) and the parietal lobe further back to the side.


Specifically, a large cerebral groove is active; the intraparietal sulcus (IPS). As the name suggests, this groove is located in the parietal lobe. This groove plays an important role in understanding numerical symbols.

The intraparietal sulcus (IPS) is active during arithmetic tasks.


If someone has difficulty writing (agraphia), damage to the parietal lobe is suspected. If someone has agraphia, it is logical that this person also has difficulty writing numbers (agraphic acalculia), and is unable to write down numbers.

Particularly on the left side of the parietal lobe

Acquired dyscalculia is more common after injury, especially in the
left parietal lobe. However, acquired dyscalculia is also reported in cases of unilateral brain damage to the parietal lobe in the right hemisphere.


Posterior Parietal Lobe 

If a general mental disorder and overt aphasia can be ruled out as the most logical cause, the combination of:

  • difficulty with arithmetic
  • difficulty writing
  • right-left confusion

should alert the practitioner to the possibility of injury or disease in the posterior parietal lobe, just above the intraparietal sulcus (IPS).


Gerstmann's syndrome

The combination of difficulties described above should therefore lead to Gerstmann's syndrome. This is defined by the following characteristics: difficulty with writing/written expression (agraphia), difficulty with simple arithmetic operations (acalculia), the inability to recognize the fingers (finger agnosia) and right-left disorientation.


Frontal lobe

As mentioned, there is a fronto-parietal arithmetic network that is active during arithmetic. If damage has occurred here, it will have an immediate impact.
The left part of the frontal lobe may be affected if the understanding of numbers or combinations of numbers is lost due to the brain injury. There have been studies suggesting that there is a common acalculia mechanism between the right and left hemispheres of the brain.


Left brain

The left hemisphere is the area where the ability for logical reasoning resides in the majority of people. The brain is structured differently in left-handed people. This skill of logical reasoning is essential for arithmetic assignments.


Wernicke area

There is a special area in the left hemisphere of the brain that, if damaged, is associated with difficulty understanding language. Difficulty with language can also result in calculation errors (aphasic acalculia). The area referred to is the Wernicke area and is located in the left temporal lobe (in the dominant hemisphere) at the border area of the parietal lobe.


                Wernicke area

Be careful with coup contrecoup injuries

If traumatic brain injury has occurred with a 'coup contrecoup injury', the effect of the brain injury can be bilateral. This can be important information if there has been an accident to the right parietal lobe of the head, where the contracoup may also have caused injury to the left parietal lobe. Then difficulty with arithmetic or numbers is an  expected consequence.
With coup contrecoup injury, damage occurs on the side of the blow; swelling and rupture of blood vessels. This is called a 'coup'. Because the brain moves slower than the skull, the brain first collides with the bone on the side of the impact. Then the brain will collide with the back or side of the skull. This is called 'contrecoup'.
Bruising and tearing of blood vessels can also occur at the back or side.
'Contrecoup' is also referred to as 'countercoup'.


How can dyscalculia be recognized?

When a person with a brain injury has to perform an arithmetic task, it is done slowly. That is, significantly slower than if that person had done that task before the brain injury. The person must think longer before naming or finding a symbol, number, amount or quantity. Just like children do, they count with their fingers as a memory aid or look at the raised fingers during an arithmetic task.
The person finds it difficult or not at all to solve the calculation task without using a calculation aid. He or she is always late when entering a check digit series at a bank or other situation where a check digit series is requested.
The aforementioned problems in daily life may also be prominent.


Learning to deal with it

Lost nerve tissue does not recover, which is why during rehabilitation and in the chronic phase, attention is paid to compensation techniques and learning to use aids. In this way, a person can adapt to life with this disability.
It is logical that if someone has difficulty with the order of numbers or if someone no longer recognizes numbers and digits, a calculator or calculator is not the solution. Then customization is required. An occupational therapist could help with this.
Society should pay attention to the following matters:

  • That there are people who have difficulty with the digital world and cannot always rely on an informal caregiver for banking matters or for completing the monthly PGB declaration.
  • That these people should be able to be helped in their own home town at a bank branch.
  • That there are people who need to continue to use cash to keep an overview of their spending patterns.
  • For example, organizations that work with people with brain injuries can choose to send the secure emails with a fixed series of numbers, for example the date of birth of the person with the injury, instead of always sending a new code by text message. If the person with the injury can no longer recognize a number, that doesn't help either.
  • Healthcare organizations, hospitals or general practitioners that offer a digital platform for their clients should also come up with alternatives to logging in with a series of numbers or to the selection menu where you need a very good memory to remember the other options.

It would be good if the IT professionals, the programmers of such programs, realized that an alternative to a series of numbers is desirable for many people. If numbers are used, please do not put them in a row, but provide spaces between the numbers.
Above all, give people a little more time...


© Hersenletsel-uitleg

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