Apraxia: classification

Definition of apraxia

Apraxia, the acquired disorder of the gesture par excellence, represents the impossibility or difficulty of coordinating gestures, despite the patient's motor capacity remains unharmed. It is a neuropsychological disorder, generally resulting in brain traumas: strictly speaking, it is understandable how apraxia is a complex and heterogeneous disorder. In this article we will analyze the various forms of apraxia, classified on the basis of the level of coordination / elaboration of the motor gesture.

Apraxia and related diseases

Before proceeding with the classification of the various forms of apraxia, a premise is necessary.

The incidence of apraxia is considerable in brain-damaged subjects: in fact, it has been observed that 30% of patients with lesions against the left cerebral hemisphere also suffer from some form of apraxia, more or less severe. As we analyzed in the introductory article, most apraxis patients are not aware of their deficits, they are normo-intelligent, they are not disabled, and both the will and the motor capacity remain unchanged. In the past, it was customary to consider apraxia within a pathological framework directly related to other movement disorders: currently, this hypothesis has been rejected, since apraxia is understood as a disorder in its own right, associated with others movement disorders, but not directly related .

Classification

First, apraxia is distinguished by the areas affected: apraxia of the limbs (ideomotor and ideational), oral (constructive and buccofacial) and of the trunk. A further classification of the forms of apraxia is carried out according to the degree of processing of the motor gesture.

• Ideomotor apraxia : typical consequence of brain lesions of the left hemisphere (in particular: trauma of the corpus callosum, damage to the parietal lobe, frontal lesion of the lateral pre-motor region). The patient is not able to translate the conceived gesture (directed to a purpose) into movement: involving the individual muscle groups, ideomotor apraxia denies the subject the possibility of performing a voluntary movement, even if he mentally designs it correctly.
• Ideational (or ideational) apraxia: the affected subject is unable to perform the movements in the correct temporal succession. In other words, the apraxical cannot mentally design the gesture and is unable to control its movements. Typical pathology resulting from lesions in the premotor cortex and in the secondary parietal cortex.
• Constructive apraxia: the apraxis patient is not able to reproduce bi / three-dimensional configurations, both on imitation and on memory. More often than not, constructive apraxia is a consequence of brain injuries to the right or left hemisphere.
• Buccofacial apraxia : the affected patient is not able to perform indicative movements with the mouth, pharynx or neck muscles, even under imitative stimulation. This type of apraxia is related to traumas of the left hemisphere, of the prerolandic and post-Rolandic region.
• Tracheal apraxia: still very controversial, trunk apraxia consists mainly of the patient's inability to coordinate the movements of the trunk and perform them correctly for a purpose (for example, the patient is unable to sit or stand up from a chair ).

Other types of apraxia include:

• Verbal apraxia: the patient is denied the possibility of coordinating the movements of the mouth, therefore to articulate the words correctly.
• Motor apraxia : the patient's significant gestures are disorganized, the movements are not very spontaneous and very forced. They generally involve half of the body affected by the affected brain area.
• Acrocinetic apraxia : the apraxis patient gestures in an awkward and bizarre, almost crystallized way; moreover, the movements, always unorganized, lack spontaneous coordination.

All newly described forms of apraxia are linked by a fundamental aspect: the apraxia is not simply correlated to the movement as such, rather it affects the organization, the planning and the coordination of the gestures and movements. The apasseic patient is not aware of how to do that given action, nor to translate the sequence of movements according to a defined scheme. In other cases of apraxia, the patient is unable to imagine that gesture, or to represent it ideally before performing it.

Clearly, the degree of severity of apraxia is directly proportional to the severity of the brain damage caused.