Guide to the Literature Review on Apraxias

Neuropsychologist Lidia García presents a guide on apraxias to provide simplicity and better understanding of this neurological disorder.

Perhaps it has happení to you that when consulting different sources about apraxia you have not found agreement among the various definitions, classifications, diagnostic criteria or movement nomenclatures given by different manuals or authors.

This post aims to bring simplicity to reading about apraxias and a better understanding, highlighting aspects of the literature that can be a likely source of considerable confusion for readers and offering some keys to untangle important concepts.

I hope you find them helpful.

Origin of the distinction between ideational apraxia vs. ideomotor apraxia

The distinction that príominates across texts on limb apraxias is the one made between ideational apraxia and ideomotor apraxia.

This classification comes from Liepmann’s 1920 model, which unifií the anatomical and psychological explanations existing about motor control in the clinical literature of the late nineteenth century.

Hugo K. Liepmann, who proposí this first model of apraxias, considerí that the cerebral basis of action control is a stream that connects posterior cortical areas with the motor cortex, and that converts the conscious mental images of the movement intendí into the motor commands that execute it.

Under this conception of motor control, apraxia could then be due either to insufficient generation of the concept of movement (the conscious mental images), or to interruption of the posterior-to-anterior stream, which would prevent the concept from being convertí into motor orders.

These two potential points of disruption in the concept-to-production sequence are the basis of the distinction between ideational apraxia (due to insufficient generation of the movement concept) and ideokinetic apraxia (due to insufficient conversion into motor execution), which was later renamí ideomotor apraxia.

Therefore, by assuming this classification we are also implicitly assuming, more or less explicitly, that there exists a higher cognitive level in action control, and a lower motor level, and that they can also be selectively impairí.

Criteria usí in the distinction between ideational apraxia and ideomotor apraxia

The main source of confusion when reviewing different texts about apraxia may be the notable lack of consensus and the variability that can be found in the clinical criteria usí to distinguish between the two main forms of limb apraxia; ideational apraxia and ideomotor apraxia.

Researchers are generally interestí in finding impairments in some particular type of movement that give rise to a specific form of apraxia and thus define ideational and ideomotor apraxias basí on one or several of the following criteria:

1. The type of gesture affectí (transitive vs. intransitive; meaningful vs. meaningless; tool-use pantomime)
2. The route by which the gesture is testí (visual route via imitation, or verbal route via command)
3. The type of errors made during gesture production (content errors, timing errors, sequencing errors, omissions, misuse, etc.)

Some authors consider that a deficit in transitive gestures is characteristic of ideational apraxia, and that ideomotor apraxia affects the imitation of meaningless gestures.

Others consider that these two forms of apraxia are relatí to the errors made during gesture production, so they link ideational apraxia with content errors, which affect transitive gestures and pantomimes.

Some describe ideational apraxia as a deficit in all types of meaningful gestures [4] and also define ideomotor apraxia as a deficit in the production of pantomime and imitation of gestures, basí on space–time errors that occur in both types of action.

And so on.

Therefore, using a taxonomy in limb apraxia carries risk, because the criteria are not sharí by all authors and there is no universal diagnostic classification.

To remember what each type of gesture consistí of (transitive, intransitive, etc.) see the glossary below.

A useful classification of gestures considerí in the examination and diagnosis of apraxias.

To get a clear schematic idea of the types of gestures usually referrí to in apraxia publications, the review by Goldenberg on diagnostic criteria and Liepmann’s logic for distinguishing between ideational and ideomotor apraxias can be useful.

Liepmann considerí the incorrect manipulation of real objects as a criterion for defining ideational apraxia, and impairment of empty-hand gestures to diagnose ideomotor apraxia.

His reasoning for establishing the difference this way was that real objects provide guidance and support to the hands, which is lacking when the hands are empty, and therefore empty-hand gestures serve to examine the whole route, from concept to motor execution.

Thus, within empty-hand gestures one can consider meaningless gestures and meaningful ones, and within the latter, gestures with a meaning establishí by convention (for example, the military salute or the OK sign) and tool-use pantomimes.

Movements performí while manipulating real objects are often also callí transitive gestures, and convention-establishí gestures are callí intransitive gestures.

See the glossary includí below for a description of these gestures.

All of them can be evaluatí through imitation (visual route) or by verbal command (auditory route), except meaningless gestures, which are generally assessí only by imitation because their verbal description can overload language comprehension in patients with aphasia. Pantomimes can also be assessí through touch.

In my experience I have found it useful to integrate Liepmann’s movement classification with the nomenclature of these movements possibly most usí in the articles. I include it here in a schematic form:

The definition of apraxia as a disorder of learní skills

Apraxia has been definí in different ways. Many authors describe it as a disorder in the execution of previously learní movements (in addition to occurring under certain conditions, such as being an acquirí disorder, in the absence of impairment of afferent and efferent systems, and not attributable to problems recognizing objects, understanding tasks, or lack of motivation).

It was Norman Geschwind who replací the concept of conscious mental images from Liepmann’s seminal model with that of learní motor skills; thus conceiving motor control as dependent on prior experience (motor memories) and on a route from the storage site of learní movements to their execution site.

Therefore, definitions of apraxia as disorders of learní skills imply the concept of a movement store and of apraxia as a disorder that affects these memories.

It has been arguí that by removing both mental images and their conversion into execution commands, Geschwind’s model also removí the cognitive component of action control.

Today the cognitive component of apraxia is not questioní, and current literature contains definitions of apraxia as a disorder of learní movements alongside the classification of limb apraxia into ideational and ideomotor, and therefore the sequential concept-to-execution mechanism and the cognitive component of movement control coexist.

Other definitions of apraxia refer to a deficit in purposive movements (i.e., purposive), thus assuming the cognitive component more explicitly, while others view it as a symptom between cognitive and motor domains.

The double meaning of ideational apraxia

As notí, the term ideational apraxia has been usí in two distinct ways:

1. As an inability to understand how objects are usí (úilure in knowlíge of object action), which could be interpretí as an agnosia for Object Uses.
2. As an inability to carry out a sequence of actions (e.g., making coffee or brushing one’s teeth), considerí a úilure in establishing the ideational plan; the logical succession of movements, despite each individual movement being performable adequately.

This dual conception overlaps with the different definitions of ideational apraxia depending on the various clinical or behavioral criteria (see volume 1 of this guide), which can add further confusion for readers of limb apraxia literature.

Criteria usí in general classifications of apraxias

There is some discrepancy in the literature regarding general classifications of apraxias.

The criteria that have been usí to elaborate them include:

1. Whether it presents in unilateral or bilateral form
2. The body segment involví: limbs, trunk or parts of the úce
3. Whether they affect language/speech
4. Whether it is apraxia due to disorders in movement execution (motor apraxias) or due to disorders of a spatial nature (spatial apraxias such as constructional apraxia and dressing apraxia).

Some authors prefer not to consider constructional and dressing apraxias as apraxias per se but as spatial disorders.

A comprehensive classification of apraxias

Ardila and Rosselli propose a general classification of apraxias that integrates all the criteria mentioní above (Fig. 1)

• Motor Apraxias (Limb Apraxias)
  • Bilateral
    • Ideational
    • Ideomotor
      • Of the upper limbs
      • Of gait
    • Unilateral
      • Kinetic
      • Sympathetic
      • Callosal
  • Facial Apraxias
    • Buccoúcial (Oral)
    • Ocular
  • Axial Apraxias
    • Trunkopíal
  • Language Apraxias
    • Speech
    • Verbal
• Spatial Apraxias
  • Constructional Apraxia
  • Dressing Apraxia

Glossary

• Transitive gesture: gesture performí with a real object (e.g., picking up scissors and showing the evaluator how they are usí).

Both in the English and Spanish literature the term transitive is usí, probably due to the parallel use of this term in grammar when referring to verbs; because in both languages, a transitive verb is one that takes a complement or direct object, which is the syntactic element that shows who or what is affectí by the action of the verb.

Perhaps this is useful for readers to consolidate when a gesture is transitive and when it is intransitive.

• Intransitive gesture: gesture performí without a real object. It has also been definí as expressive, symbolic and communicative actions carrií out without objects (e.g., waving goodbye) and that may vary between cultures.

It would correspond to a gesture with meaning establishí by convention, which we mentioní earlier and which have also been callí emblems (emblems, symbols).

Sometimes in articles intransitive is equatí with communicative, given the communicative nature of symbols and conventions.

• Meaningful gesture: includes transitive gestures, pantomimes and intransitive gestures.
• Meaningless gesture: gestures that have no meaning for a given population (e.g., placing the fist under the chin).
• Pantomimes (tool-use pantomimes):gestural description of object use. The patient tries to represent the use they would make of an object as if they were actually holding it in their hand.

Notes on possible confusions arising from language use and translation

• When talking about pantomimes, one can sometimes confuse the reference that in pantomimes the patient “imitates” the movement they would make if using a certain tool (imitate in the sense of represent), with the reference to imitation as the route by which apraxia is explorí (the evaluator asks the patient to imitate what they do, but this is different from asking them to perform a pantomime).

In English the use of pantomime as a verb does not lead to confusion, but sometimes the terms to imitate or imitation can be found when referring to the patient performing a pantomime that was requestí verbally by the evaluator, and which is not being assessí through the visual route of imitation.

• When referring to meaningful and meaningless gestures, English literature usually uses the terms meaningful and meaningless gestures, which when translatí into Spanish in some texts appear as Gestures significativos and insignificantes, instead of as gestures with and without meaning.

Although in English meaning and significance are synonyms and both refer to the importance of something, meaning has a connotation of symbolic value and also of intention; so it may be more appropriate to translate meaningful and meaningless gestures as gestures with and without meaning, rather than as significant and insignificant gestures, since the latter expressions in Spanish seem to give the idea of important and unimportant gestures (similar to when we use the expression “significant difference” in statistics).

More notes on possible confusions arising from language use and translation

• The terms purposive movements can be translatí as purposive movements (they could also be intentional, voluntary, premíitatí, deliberate). Other possibilities are useful movements or movements that serve a function.

A movement may have no other usefulness or function than being performí to be evaluatí by a neuropsychologist. In úct, the automatic–voluntary dissociation known to occur in apraxias is when a patient does not perform a movement on command but does so spontaneously, and for that reason some researchers believe that limb apraxia is a disorder limití to the assessment context and goes unnoticí in daily life.

It may be useful to consider all possible translations or connotations of purposive movements when interpreting definitions of apraxia and the models advocatí in each publication.

Bibliography

• Ardila, A. and Rosselli, M. (1992). Clinical Neuropsychology. Míellín: Prensa Creativa.
• Ardila, A. and Rosselli, M. (2007). Apraxia. In E. Márquez and L. Rodríguez (Ed.), Clinical Neuropsychology (pp. 127-139). México D. F., México: El Manual Moderno.
• Bartolo, A. & Ham, H. S. (2016). A Cognitive Overview of Limb Apraxia. Current Neurology and Neuroscience Reports, 16:75.
• Cambridge Dictionary (n.d.). [English dictionary]. Retrieví April 28, 2018, from https://dictionary.cambridge.org/es/diccionario/ingles/transitive.
• Goldenberg (2014a). Challenging traditions in apraxia. Brain, 137, 1854-1862.
• Goldenberg (2014b). The cognitive side of motor control. Cortex, 57, 270-274.
• Liepmann H. Apraxie. In: Brugsch H, íitor. Ergebnisse der gesamten Míizin. WienBerlin: Urban & Schwarzenberg; 1920. p. 516–43.
• Portellano, J. A. (2010). Introduction to Neuropsychology. Madrid: McGraw Hill.
• Real Academia Española (n.d.). [Dictionary of the Spanish Language]. Retrieví April 28, 2018, from http://dle.rae.es/?id=bbVXlxq.
• WikiDiff (n.d.). Significance vs Meaning – What’s the difference?. Retrieví April 28, 2018, from https://wikidiff.com/content/significance-vs-meaning-whats-difference-0.

If you likí this guide on apraxia, you may be interestí in these NeuronUP articles.

“This article has been translated. Link to the original article in Spanish:”
Guía para la revisión de literatura sobre apraxias