Apraxias are disorders of the nervous system that affect our execution of previously learned movements or tasks. They imply a difficulty in motor planning and its execution (for example, it can make it difficult for us to think about how to send a letter and sequence the steps: I write the letter, I put it in an envelope, I close an envelope and send it).
Apraxias prevent us from performing actions if someone asks us to do them or if we have the intention to do them (although we find them much easier to perform if we do it spontaneously). Thus, they make it difficult for us, for example, to shake hands, get dressed, open an envelope, draw, make a small construction with pieces or use certain tools.
In this article we will learn in more detail what this neurological disorder consists of, what its possible causes are, the brain areas involved and the different types of aphasia that exist.
What are apraxias?
Praxias were defined by Steinhal in 1871, cited in , as “coordinated motor actions that are carried out to achieve an end” (p.). These are complex movements that have previously been learned.
Returning to the term apraxia; The prefix “a” of the concept of praxia implies the “absence of”; in this case, the absence of the ability to execute previously learned movements.
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So, according to the medical portal, we can define apraxia as “a disorder of the brain and nervous system, which makes the person unable to perform certain tasks or movements when asked, even if they have understood the request or order, are willing to do it, has learned the task and/or the muscles necessary to carry it out work properly.”
Two systems
We find two systems involved in apraxias:
- Conceptual system: It has to do with the knowledge we have about the use and functioning of objects, utensils and tools.
- Production system: For its part, this system allows us to store and carry out the sensorimotor representation (spatial and temporal) necessary to be able to execute the motor activity. That is, it allows us to execute the movement.
Characteristics and symptoms of apraxias
The main symptom of apraxias is an inability to execute previously learned movements. In order to speak of apraxia, there must be no paralysis, paresis or ataxia as the primary cause of the motor difficulty. Nor should there be an intellectual deficit that justifies the inability to execute the movement.
There is also an absence of any type of attentional, confusional or delusional disorder, as well as the absence of sensory disorders that justify the motor deficit.
A person with apraxia fails when asked to imitate or perform an intentional movement; However, motor activity may be preserved when he performs it spontaneously.
In the event that the side opposite the injury is affected, we speak of hemiapraxias, although in these cases execution on both sides may also be affected.
What causes apraxias?
We find different causes that explain apraxias, although basically these are caused by brain damage.
Apraxias are acquired disorders; That is, they arise once the person has already learned the tasks or skills that he or she subsequently fails to carry out. Among the causes of apraxias we find:
- Brain tumors.
- Traumatic brain injuries (traumatic brain injury).
- Cerebrovascular accident (hemorrhagic or ischemic stroke).
- Hydrocephalus.
- Neurodegenerative diseases (that progressively worsen the functioning of the brain and nervous system).
- Dementia.
Brain areas involved in apraxias
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At a neurological level, there are different brain areas that can be involved (and therefore damaged) in apraxias. This is because these areas are related to the functions that a healthy person could perform perfectly if they did not have apraxia. Between them:
- premotor area
- Supplementary premotor area
- occipital lobes
- Parietal lobes
- Temporal lobes
- Basal gray nuclei
- Hard body
- Thalamus
8 types of apraxias
There are several types of apraxias depending on their characteristics, affected brain areas, etc. We are going to know what each of them consists of and illustrate them with examples:
Ideatory apraxia
The person manifests an inability to manipulate previously known objects and tools. For example, he cannot use a knife if asked (although he could spontaneously).
Thus, it is characterized by the inability to execute a series of sequenced propositional gestures aimed at a goal, as a consequence of the loss of the action plan. In this type of apraxia the conceptual system is altered.
Ideomotor apraxia
In ideomotor apraxia, what is affected is the performance of simple gestures, although the ability to manipulate real objects and tools is preserved. For example, the person may not wave if asked.
This type of apraxia affects the purposeful execution of simple movements, executed deliberately and out of context. It is important to know that there are no sensory or motor deficits or cognitive impairment in the subject that explains it.
Here the conceptual system already explained is preserved, but the production program or production system is damaged or altered. This would explain why there is a failure in the transmission of messages to the motor area in the frontal lobe.
Constructive apraxia
This is an inability to reproduce drawings or assemble two-dimensional or three-dimensional pieces, which makes it impossible to carry out tasks such as models, designing plans, building with cubes or copying a simple drawing.
Dressing apraxia
In dressing apraxia there is an inability to dress oneself independently. In this way, the person does not know how to orient themselves with clothing, being unable to sequence the order, which causes them to dress in a clumsy and awkward manner. This type of apraxia usually appears together with anterior (constructive) apraxia.
gait apraxia
In this case, the inability occurs in the fact of walking correctly voluntarily, although spontaneously (not thought or planned) the person may be able to walk properly. It is usually associated with serious brain diseases, such as tumors, dementia or hydrocephalus.
Buccophonatory apraxia
Buccophonatory apraxia is the inability to make voluntary movements of the face, lips, tongue or phonatory organs. This translates into an inability to perform gestures such as blowing, sticking out the tongue or showing teeth.
However, as in other apraxias, the ability to perform the movement spontaneously may persist.
Optic apraxia
A person with optic apraxia cannot perform visual search movements in guided movements. That is, if, for example, she is looking at a room and is asked to look for a more or less hidden book, she cannot perform this visual search action.
Callous apraxia
Finally, apraxia callosa has to do with the inability to execute motor activities through verbal command (that is, if someone asks us to do a certain movement or task).
It arises from the absence of the corpus callosum, which prevents the left hemisphere from transmitting the appropriate commands to the right to move the left hand.
Thus, the left hand is affected, and is caused by hemiapraxia produced by a callosotomy (section of the corpus callosum).
References:
- MedlinePlus. (2021). Apraxia. Recovered from:
- Portellano, J. A. (2005). Introduction to neuropsychology. Retrieved from
- Rains, G.D., & Campos, V. (2004). Principles of human neuropsychology. Mexico: McGraw-Hill.
- Rosenweig, M.R., Breedlove, S.M. & Watson, N.V. (2005). Psychobiology: An introduction to behavioral, cognitive, and clinical neuroscience. Barcelona: Ariel.