Aphasia: Differential Diagnosis and Types of Aphasia

In this article, neuropsychologist Lidia García Pérez explains what aphasia is and the types of aphasia, and distinguishes this disorder from speech disorders, dysarthria, and cognitive-communicative impairment.

What is aphasia?

Aphasia is a loss or disorder of language caused by brain damage [1], typically associated with lesions in the language-dominant hemisphere (the left hemisphere in 96% of right-handed people and 70% of left-handed people [2]).

The term comes from the Greek ἀφασία, meaning “inability to speak” [3]. However, this disorder can affect, in different ways and to different degrees, both language production and language comprehension, in any of their modalities: oral expression, oral comprehension, writing, or reading [4,5].

As a result, very different syndromes can be described within it, depending on which language skills are affected, and these can also coexist with other cognitive deficits.

Aphasia, speech disorders, and communication disorders 

Since the language disorder involved in aphasia also impairs the ability to communicate, it’s important to distinguish it from other types of communication impairments, whether or not they are due to acquired brain injury, such as speech disorders and neuropsychological disorders such as apraxia of speech or cognitive-communicative impairments [4].

Aphasia vs. speech disorders

Speech disorders, such as dysphonia, stuttering, dysglossia, dyslalia, or dysarthria, are impairments of different origins (oral-phonatory or neurological) that affect various aspects of speech, such as the acoustic qualities of the voice (loudness, pitch, and timbre), fluency, pronunciation, or the articulation of phonemes and words, but in which language itself is preserved [5].

Aphasia, on the other hand, is characterized by an impairment in the structure of language that affects its semantic, grammatical, phonological, and/or syntactic level, damaging its symbolic nature [5], that is, the ability of language to represent ideas or thoughts. So, while aphasia is a specific language impairment that affects its oral modality and the ability to communicate, speech disorders also affect communication, but not language.

In some cases, aphasia can be accompanied by apraxia of speech, which, like aphasia, is a neuropsychological disorder acquired through brain damage. It involves difficulty voluntarily performing the articulatory movements of speech due to a lesion in the motor association areas of the cortex responsible for programming the voluntary movements of the muscles of the mouth, tongue, and larynx [2,5]. Although some types of aphasia, such as non-fluent aphasias, may include apraxia of speech as a symptom, apraxia of speech itself is a motor planning problem.

In a clinical assessment, apraxia of speech can be identified by difficulty moving the muscles of the mouth, tongue, and larynx in tasks other than speaking [2], such as swallowing, blowing, whistling, chewing, or kissing.

Activities for neuropsychological rehabilitation in patients with Broca’s aphasia

Aphasia vs. dysarthria

Another useful distinction is between apraxia of speech and dysarthria, a neuromuscular disorder in which the execution of speech movements is also impaired, affecting articulation, but not because of a movement planning problem; rather, it’s a problem activating the muscles involved.

Clinically, they can be distinguished because in dysarthria, articulation errors are consistent and word length has less influence, while in apraxia of speech, word length has more influence on errors and the errors are not consistent [4]. In addition, apraxia of speech shows an automatic-voluntary dissociation [4] (for example, the patient may have difficulty smiling on purpose but can smile spontaneously).

Aphasia vs. cognitive-communicative impairment

When we speak, listen, read, or write, it’s not only linguistic aspects that come into play; these skills also require other cognitive functions, such as attention, memory, executive functions, reasoning, and abstraction [4].

That’s why we need to be able to distinguish between a primary language problem (aphasia) and language problems secondary to deficits in those other functions, which have been called cognitive-communicative impairments and affect behavior regulation, social interaction, activities of daily living, learning, and academic and professional performance [4].

Types of aphasia

A first classification criterion, useful in the differential diagnosis of types of aphasia, is usually the distinction between fluent aphasia and non-fluent aphasia [7]. In non-fluent aphasia, expressive language is less preserved than receptive language; when the opposite is true, it’s considered fluent [5].

Non-fluent aphasias

According to the classic classification [4, 7], non-fluent aphasias include Broca’s aphasia, transcortical motor aphasia, and global aphasia, while fluent aphasias include Wernicke’s aphasia, transcortical sensory aphasia, conduction aphasia, and anomic aphasia.

Patients with Broca’s aphasia usually have difficulty with spontaneous speech, poor fluency, telegraphic speech, agrammatism (grammatical and syntactic errors), and difficulties with naming and repetition, while comprehension is relatively better preserved [5,6]. When a patient has a similar picture but no repetition problems, it’s classified as transcortical motor aphasia [6].

In global aphasia, there are severe problems with both comprehension and production [5,6].

Fluent aphasia

In Wernicke’s aphasia, comprehension and naming are severely affected, and oral expression is fluent but full of paraphasias (incorrect constructions or substitutions of one word for another) and neologisms (words that don’t exist) [5,6]. In transcortical sensory aphasia, the patient has the problems of Wernicke’s aphasia except for difficulty with repetition [6].

When difficulty with repetition is the main problem, it’s classified as conduction aphasia. In anomic aphasia, there is only a naming deficit.

Although this classification is probably the most widespread, the differential diagnosis of aphasias using this or any other taxonomy of syndrome groups has some limitations in practice, a topic we will address in a future post.

References

• Ardila, A. & Benson, D. F. (1996). Aphasia: A clinical perspective. New York: Oxford.
• Scott J. G. and Schoenberg, M. R. (2011). Language problems and assessment: the aphasic patient. In Schoenberg, M. R. & Scott J. G. (Eds.). The little black book of neuropsychology: a syndrome-based approach (pp. 159-178). New York, Dordrecht, Heidelberg, London: Springer.
• Real Academia Nacional de Medicina (2012). Diccionario de términos médicos. Madrid: Panamericana. Recuperado de http://dtme.ranm.es/ingresar.aspx
• 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: ElsevierMasson.
• Portellano, J. A. (2010). Introducción a la neuropsicología. Madrid: McGraw Hill.
• 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.
• Ardila, A. y Roselli, M. (2007). Neuropsicología clínica. México, D. F.: El Manual Moderno.

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Afasia: diagnóstico diferencial y tipos de afasias