There are multiple causes that can lead to brain injury . Similarly, the impact of an injury on the nervous system can produce a wide variety of symptoms depending on the area affected and the type of damage that has occurred.

Examples of this can be problems with speech understanding, perception of stimuli through the senses or problems linked to the motor system. Within the latter type of problems, one can find the difficulty or loss of capacity when performing sequential movements, which are used on a daily basis when performing very diverse actions. We are talking about apraxias .

A little preamble: what kind of moves do we make?

In order to understand what an apraxia is, we need to take into account the great diversity of movements that we make. Whether they are voluntary or not, the capacity for movement has allowed human beings to develop as a species and to be able to execute actions of great complexity.

Some of the main movements that human beings make are the following.

1. Reflexes

These types of movements tend to be intense reactions of little complexity and duration , generally due to the activation of a bundle of specific nerve fibres. These are small movements performed involuntarily.

2. Voluntary movements

Voluntary movements are those that we carry out with a certain goal , at a conscious level and that at least originally need the individual’s attention in order to be carried out correctly. With enough practice, they can be automated.

3. Automatic movements

On this occasion a behaviour is performed voluntarily, but it is automated , i.e. no conscious attention to the sequence of actions is required to carry it out beyond choosing its start and/or end moment. These are sequences of actions that are internalized thanks to the practice and habituation of the person to carry them out, such as the set of actions that we carry out to eat soup, ride a bike, drive, sit down or even talk or walk. It is in this type of movement that apraxia appears.

Describing the concept of apraxia

Once the above brief explanation is taken into account, it is easier to explain the concept of apraxia. It is understood as such when the capacity to perform propositional movements that require sequencing and coordination of movements ceases or becomes very difficult, making it impossible to perform certain automatic movements.

This alteration is generally due to a brain injury, keeping the subject who suffers it the ability to understand the action he is asked to do, being the task easy to perform or being this already known by the individual and maintaining a correct muscle function. Generally, the individual does not present anosognosia, so he is fully aware of his deficit.

Most popular types of apraxia

As we have mentioned, apraxia implies an impossibility to carry out sequences of coordinated movements in a sequential and ordered way.

However, n o there is only one typology of this problem, there being a large number of classes of apraxia . Some of the main ones are reflected below.

1. Ideational apraxia

In this type of apraxia the subjects have a difficulty not only in carrying out coordinated tasks, but also in imagining them , not being able in many cases to imagine the correct sequence necessary to carry out a specific behaviour. However, the individual actions that make up the sequence can be carried out correctly.

It is also considered as ideational apraxia (although in this case it is also called conceptual) the difficulty to use objects due to the same causes, that is to say, the lack of knowledge of the sequence of actions necessary to use, for example, a comb. It is common in neurodegenerative diseases such as Alzheimer’s or Parkinson’s dementia, as well as in injuries of the dominant hemisphere and the corpus callosum.

2. Ideomotor apraxia

This type of apraxia is the most common in clinical practice. On this occasion, the subjects can correctly imagine the sequence of actions necessary to carry out a given behavior, although they are not capable of carrying it out physically .

In the ideomotor apraxia the deficit is found in a difficulty in the planning of the movement. Within this typology, different subtypes could be found, such as buccofacial apraxia, speech apraxia, limb apraxia and axial apraxia (of the body axis, affecting actions such as sitting and posture). They are frequent in bilateral injuries and cortico-basal degenerations, being generally affected both sides of the body.

3. Constructive apraxia

As for constructive apraxia, it is based on the difficulty in construction or drawing due to difficulties in spatial perception and oculo-manual coordination . Thus, there is not a correct association between the image perceived visually and the movements necessary to carry out the elaboration. Some subjects with this type of problem are incapable of recognizing the differences between the stimulus they are asked to copy and its elaboration, and it is even discussed whether the problem is one of movement or of integration between information.

Also called visuoconstructive deficit, this type of apraxia is used as an indicator of cognitive impairment due to its early appearance in Alzheimer’s patients. It usually appears in patients with lesions in the right hemisphere, but a large number of cases have been observed where the damaged hemisphere is the left one. The lesion is usually located in the parieto-occipital region, which is consistent with the lack of coordination between vision (located mainly in the occipital lobe) and movement (present in the parietal).

Possible causes

Apraxia, as a product of brain injury, can have a wide variety of causes . Although the list of possible causes is much longer, some of them may be the following.

Cardiovascular accidents

Whether it is a haemorrhage or a stroke , cardiovascular accidents often cause the death of a part of the brain , being the most common cause of the appearance of apraxia and other disorders linked to brain injury.

Head injuries

A contusion affecting the brain can cause serious damage to this organ, which may or may not be reversible . Depending on the area damaged by the blow, or the possible kickback (i.e. the blow produced on the side opposite the injury due to the bounce against the skull), apraxia can easily occur.

Brain Tumors

The presence of a strange and growing mass in the brain causes damage in various areas of the brain , both due to the tumor itself and to the pressure exerted on the brain against the skull. If this damage occurs in the areas responsible for the motor system or in areas of association that integrate the coordination of movements, the appearance of an apraxia is greatly facilitated.

Neurodegenerative disease

Disorders with a progressive deterioration of the nervous system are closely linked to the presence of apraxia. In fact, one of the characteristics of cortical dementias is the presence of the aphaso-apraxo-agnostic syndrome , which includes the progressive appearance of problems with speech, movement sequencing and perceptive and intellectual abilities.

Treatment

Being generally the product of brain injuries, apraxia is problematic and the form of treatment will vary greatly depending on the cause. Although they are difficult to recover from and in some cases may have consequences, the type of treatment carried out generally tends to use therapy at a physical level, and rehabilitation or compensation for lost functions.

Bibliographic references:

  • Ardila, A. (2015). Kinetic, ideomotor, ideational and conceptual apraxia. Neuropsychology, Neuropsychiatry and Neurosciences Journal, Vol.15, Nº1, pp. 119-139
  • Bradley, W.G.; Daroff, R.B. et al. (2004) Clinical Neurology: Diagnosis and Treatment. Vol I. Fourth Edition. Pages 127-133.
  • Garcia, R. and Perea, M.V. (2015). Constructive and dressing apraxia. Journal Neuropsychology, Neuropsychiatry and Neurosciences, 15, 1, 159-174.
  • Greene, J.D.W. (2005). Apraxia, agnosias and higher visual function abnormalities. J Neurol Neurosurg Psychiatry; 76:v25-v34.