Afasia: diagnósitco diferencial

Aphasia: Differential Diagnosis


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Aphasia is the loss or impairment of language function caused by braindamage [1] that is typically associated with lesions in the language-dominan themisphere (the lef themisphere for 96% of right-handed and 70% of left-handed individuals [2]).

This term comes from the Ancient Greek word ἀφασία which means “speechlessness” [3]. However, this disorder can also compromise—in many different ways and to many different degrees—both language production and comprehension in any of its modalities: oral expression, auditory comprehension, reading or writing [4,5]. Therefore, depending on the linguistic abilities that are impaired—and which can also coexist with other cognitive deficits—aphasic syndromes can be very heterogeneous.

Aphasia, Speech Disorders and Communication Disorders

Since aphasia (as a disorder of language) also involves a deterioration of communication skills, it is important to discriminate between this disorder and other types of communication disorders that can result from acquired brain injury such as speech disorders and neuropsychological disorders such as apraxia of speech or cognitive-communication disorders [4].

Aphasia vs. Speech Disorders

Speech disorders such as dysphonia, dysphasia, dysglossia, dyslalia, or dysarthria are alterations of different origins (buccophonatory or neurological) that affect various parameters of speech such as the acoustic characteristics of voice (intensity, tone, and timbre), fluency, pronunciation, and the articulation of phonemes and words, but in which language is preserved [5].

Aphasia, on the other hand, is characterized by an alteration in the structure of language affecting its semantic, grammatical, phonological and/or syntactic level, which deteriorates its symbolic nature [5], that is, the capacity of language to represent ideas or thoughts.

Therefore, while this disorder is a specific impairment of language that affects its oral modality and the ability to communicate, speech disorders affect communication but not language.

In certain cases, aphasia may co-occur with apraxia of speech, which is, like aphasia, an acquired disorder resulting from brain injury. Apraxia of speech is characterized by an impaired ability to execute voluntarily the appropriate movements for articulation of speech due to a lesion in motor association areas of the cerebral cortex responsible for the programming of voluntary movements of the musculature of the mouth, tongue and larynx [2, 5]. Although some aphasic syndromes such as non-fluent aphasia may include apraxia of speech as a symptom, apraxia of speech itselfis an alteration of kinetic planning.

In clinical evaluations, the motor apraxias can be distinguished by the fact that difficulty in moving the musculature of the mouth, tongue and larynx will also be present with tasks other than talking [2], such as swallowing, blowing, whistling, chewing or kissing.

Another useful distinction is that between apraxia of speech and dysarthria. Dysarthria is a neuromuscular disorder in which the execution of speech movements is likewise impaired and affects articulation but is not due to a difficulty in the planning of movements, but rather to a problem of activation of the muscles involved in speech production. Clinically, they are distinguishable in that, in apraxia of speech, articulation errors are inconsistent and increase as a function of word length, whereas in dysarthria, articulation errors are consistent and are relatively uninfluenced by word length [4]. In addition, apraxia of speech has automatic-voluntary dissociation [4] (for example, patients may have difficulty smiling consciously but may spontaneously smile).

Aphasia vs. Cognitive-Communication Disorders

On the other hand, when we speak, listen, read or write, not only linguistic aspects intervene, but these abilities also require other cognitive functions such as attention, memory, executive functions, reasoning or abstraction [4]. Therefore, we must be able to discriminate between problems primarily related to language (aphasia) and language problems secondary to deficits in other functions. These problems have been termed cognitive-communication disorders and affect behavioral self-regulation, social interaction, activities of daily living, learning and academic performance, and vocational performance [4].

Types of Aphasia

A first classification criterion helpful in differential diagnosis of aphasia is usually the distinction between fluent and non-fluent aphasia [7]. If it is non-fluent, expressive language is less preserved than receptive language and, if the opposite occurs, it is considered to be fluent [5].

According to the traditional classification of different types of this disorder [4, 7], non-fluent aphasias include Broca’s aphasia, transcortical motor aphsia, and global aphasia; fluent aphasias include Wernicke’s aphasia, transcortical sensory aphsia, conduction aphasia, and anomicaphasia.

Patients with Broca’s aphasia often show difficulty with spontaneous speech, poor fluency, telegraphic speech, agrammatism (grammatical and syntactic errors) and difficulty with naming and repetition, whereas comprehension is relatively preserved [5,6]. If a patient presents similar symptoms to those of Broca’s aphsia but does not exhibit repetition problems, transcortical motor aphsia would be inferred [6].

In Wernicke’s aphasia, comprehension and naming are severely impaired. Oral expression, while fluent, contains abundant paraphasias (word structure errors or substitutions of one word for another) and neologisms (nonexistent words) [5,6]. In transcortical sensory aphasia the patient presents the typical symptoms of Wernicke’s aphasia except that repetition is preserved [6].

If the patient’s main problem is with repetition, this would be conduction aphasia. In anomic aphasia, there is a deficit in naming ability. Finally, in global aphasia, both comprehension and production are severely impaired [5,6].

Even though this classification is probably the most widely accepted, the differential diagnosis of aphasias through this or any other taxonomy of syndromic groups, presents some problems in practice, an issue that will be addressed in a future post.

Bibliography

  1. Ardila, A. y Benson, D. F. (1996). Aphasia: A clinical perspective. Nueva York: Oxford.
  2. Scott J. G. y Schoenberg, M. R. (2011). Language problems and assessment: the aphasic patient. En Schoenberg, M. R. y Scott J. G. (Eds.). The Little Black book of neuropsychology: a syndrome-based approach (p. 159-178). New York, Dordrecht, Heidelberg, London: Springer.
  3. Real Academia Nacional de Medicina (2012). Diccionario de términos médicos. Madrid: Panamericana. Recuperado de http://dtme.ranm.es/ingresar.aspx
  4. Gispert-Saúch, M. M. (2011). Lenguaje, afasias y trastornos de la comunicación. En Bruna, O., Roig, T., Puyuelo, M., Junqué, C. y Rueano, A. (Eds.). Rehabilitación neuropsicológica: intervención y práctica clínica (p. 61-81). Barcelona: Elsevier Masson.
  5. Portellano, J. A. (2010). Introducción a la neuropsicología. Madrid: McGraw Hill.
  6. Cuetos, F., González, M., Martínez, L., Mantiñán, N., Olmedo, A. y Dioses, A. (2010). ¿Síndromes o síntomas en la evaluación de los pacientes afásicos?.Psicothema, vol. 22(4), pp. 715-719.
  7. Ardila, A. y Roselli, M. (2007). Neuropsicología clínica. México, D. F.: El Manual Moderno.

By: Lidia García

Translated by Silvia Duque

Lidia García Pérez
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