At the beginning of the last century, Josef Gerstmann met a patient who, after a brain injury, was unable to name the fingers of his hand , or even recognize them. Moved by the interest in this curious symptom, he found a constellation of symptoms accompanying this phenomenon.

Let’s look at Gerstmann’s syndrome , a clinical picture that occurs after an injury to the parietal lobes. We will describe what its symptoms are, where the lesion is located and what causes it to occur.

Symptoms of Gerstmann syndrome

When we talk about Gerstmann’s original patient, we always mention the four classic symptoms: digital agnosia, agraphia, achalculia and laterality problems.

If these four cardinal points are present at the same time in a patient, we say that he suffers from Gerstmann’s syndrome.

1. Digital Agnosia

This is a form of asomatognosia, that is, the inability to recognize parts of one’s body . This symptom can affect either side of the body depending on which brain hemisphere is affected. Interestingly, the inability to recognize the fingers is closely related to the presence of dyscalculia. Those children who are unable to recognize their own fingers due to injury or malformation have much more difficulty learning to calculate.

2. Agraphia

The patient with Gerstmann syndrome is unable to communicate in writing . Agraphia can occur for two different reasons: either an injury that causes language deficits or an injury where language ability is fine but motor skills are affected.

In the case of Gerstmann’s syndrome it is not clear what the reason for this is. While some patients also have other language disorders such as inability to read or aphasia that may be related, we also know that a common denominator in the syndrome is the inability to manipulate images mentally. Both hypotheses are up in the air.

3. Dyscalculia

This is the name given to the difficulties in performing arithmetic head operations . Patients with Gerstmann syndrome have difficulties with even the simplest addition and subtraction. It remains to be seen exactly at what point in the arithmetic operations the disability occurs. Perhaps it is in the retention of numbers in consciousness, as a kind of working memory for arithmetic operations.

4. Laterality problems

Gerstmann’s patient was completely unable to differentiate left from right . This is not cross laterality, where both directions are confused, but the loss of the notion of laterality. For this person, left and right do not exist and he responds randomly to the tests made on him.

Other symptoms are added to this classic tetralogy and may or may not be present depending on the patient. The lesions in each case are unique and will result in a different clinical picture, although all (or almost all) will have these four key points. Many patients show a fifth symptom not included in tetralogy, but which has become more and more relevant in case descriptions over the century.

5. Aphasia

The inability to articulate language can be observed in many patients with Gerstmann syndrome , indicating that more than an affectation of concrete abilities, what could be affected in reality is symbolic thinking. Moreover, it could even be that the inability to understand abstract concepts explains why patients do not know what to answer when asked where the right or index finger is, confusing digital agnosia with receptive aphasia.

Causes of this syndrome

The syndrome occurs due to injury in the left parietal region of the brain, specifically the angular convolution . The parietal region is responsible for motor and sensory functions, spatial aspects, calculus and part of the language. It is normal, then, that a lesion somewhere in the parietal lobe, due to geographical and also functional proximity, should affect this whole group.

It is common for regions that are close to each other to carry out similar functions or to complement each other, as if they had each specialized in a particular aspect of a more general function. For example, motor and sensory functions are closely related, and one is next to the other. Thus, an injury to the motor function can also alter sensitivity and vice versa. This is why an apparently focal lesion can affect a whole subsystem of related components.

The reasons why someone could suffer damage to the parietal lobe are multiple . Head injuries, through the blow itself or the edema that follows, brain tumours or even strokes are common causes of this syndrome. It is very common to find people who have lost the blood supply to this area of the brain, losing the neurons in charge of these functions.


The treatment of Gerstmann’s syndrome is symptomatic. There is nothing that can be done to automatically restore the damage, but this does not mean that the individual cannot rehabilitate himself and relearn all those skills he has lost. Depending on the injury, the severity of the injury, and the age of the individual, the prognosis is different.

To get an idea, we must think that the brain is very plastic and has the capacity to reorganize itself to assume the functions that have been lost. As if the workers of a company assume the responsibilities of an entire department that has just been dismissed, but without cost. The younger the brain, the more adaptable it is.

With progressive training it is possible to restore functions. It is not always possible to return to pre-syndrome function, especially if the affected area is very large or the injuries are deep, but disability is ruled out if cognitive rehabilitation is followed thoroughly.