The role of neuropsychology in aphasia

Given its complexity, it is necessary to have a team made up of many professionals who, from different approaches, aim to help the patient recover as much function as possible and facilitate the adaptation of the person to their new life situation. Speech therapists, occupational therapists, physiotherapists, social workers and clinical psychologists, all must provide their assessments and, if necessary, their treatment options. Of course, neuropsychologists also play an important role in this process, which will be addressed in this article.

The neuropsychologist is responsible for describing the cognitive profile of persons with aphasia following brain injury. Therefore, when language is understood as a cognitive function, it is difficult to separate it from other functions that interact with it and are also influenced by it, such as working memory, executive functioning and memory, among others (1). Understanding this profile can be key to knowing what abilities have been preserved before starting rehabilitation.

In addition, neuropsychology is one of the fields responsible for directing the different advances in neuroscience regarding language function and developing new methods for approaching rehabilitation, moving from asyndrome model or approach to a model based on language processes (2,3).

Neuropsychological assessment of aphasia

The framing model

One of the main requirements for neuropsychological assessment of language is having a model that enables us to understand how language functions. The Classic Model, often referred to as the “Wernicke-Geschwind model” (4), is commonly used. This model proposes a syndrome classification but is insufficient to describe the language alterations present in individuals with aphasia, and thus, not very specific tobe used for assessment and subsequent rehabilitation. Moreover, there are other models that can be more useful.

At the functional-anatomic level, the dual-stream model proposed by Hickok and Poeppel (5) postulates two pathways that are relevant to language production and language comprehension. A dorsal stream (analogous to the Wernicke-Geschwind model) supports phonological and motor processing whereas a ventral stream deals with auditory comprehension and is more involved in semantic processing. Subsequently, Friederici and Gierhan (6) proposed a model comprising at least two dorsal and ventral streams, each serving different language processes associated to different fascicles.

At the cognitive level, the Ellis and Young model of monolingual language processing (7) allows clinicians to dissociate several processes within the different aspects of language that have usually been assessed, and therefore, to discern the cause of the impairment more clearly. This model provides a foundation for the development of a successful approach to aphasia treatment.

The key to designing a rehabilitation program, therefore, lies in the ability to detect which language processes are impaired and which are not. To this end, it is essential to identify the different dissociations by having the subjects perform specific tasks and then analyzing any errors exhibited by them.

PALPA (Psycholinguistic Assessments of Language Processing in Aphasia) is a clinical instrument designed to assess language processing skills in people with aphasia. It consists of several tests that examine components of language structure. Another interesting tool is the Pyramids and Palm Trees Test (PPT), which measures the capacity to retrieve semantic information from pictures.

It should also be noted that, in most cases, an assessment should be conducted to determine how other cognitive functions may be affecting language in general or some process in particular.

Final Observations

It should not be forgotten that, in many cases, neuropsychological assessment goes beyond identifying impairments; considering the effects of these difficulties is therefore important as every person is unique. It can be then said that each individual with aphasia exhibits different features and that an adequate approach can only be based on that particular individual.

The neurofunctional tests commonly used to assess the impact of brain injury on daily life are little or no longer sensitive to the impact of language impairments on our lives (8). The administration of specific tests such as the communicative effectiveness index, CADL-2 (Communication Activities of Daily Living) and the Communicative Activity Log (CAL) is recommended.

Neuropsychological rehabilitation of language

Rehabilitation approach

On this basis, the approach to neuropsychological rehabilitation should focus on training the impaired processes identified by a previous assessment. Methods of rehabilitation include classic techniques such as errorless learning and sentence/picture matching tasks (for example, associating sentence elements and sentence order with colors to train a grammatic patients). Having reached this point, it is clear that treatment should be tailored to the specific needs of each individual.

Having said this, the REGIA program (intensive aphasia therapy within a group setting) is remarkable because it uses the principle of constraint of non-verbal expression. It is an intensive therapy with demonstrated efficacy in group settings (9).

The use of alternative communication systems is also a good option to compensate for the patient’s most severe language difficulties. We should keep in mind that people affected by aphasia may need to adapt to changes in their environments and understand the world in a new way (10), so intervention should also occur outside the therapist’s office.

Chronicity

Finally, it should be noted that neuropsychological intervention in aphasia has been shown to be very effective in the year following brain injury, but has as well been proven to yield significant improvement at the chronic stage (9).

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Bibliography

1. Cahana-Amitay D, Albert M. Redefining Recovery from Aphasia. Oxford, New York: Oxford University Press; 2015. 296 p.
2. Tremblay P, Dick AS. Broca and Wernicke are dead, or moving past the classic model of language neurobiology. Brain Lang. 1 November2016;162:60-71.
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4. Geschwind N. Disconnexion syndromes in animals and man. I. Brain J Neurol. June 1965;88(2):237-94.
5. Hickok G, Poeppel D. Dorsal and ventral streams: a frame work for understanding aspects of the functional anatomy of language. Cognition. June 2004;92(1-2):67-99.
6. Friederici AD, Gierhan SM. The language network. Curr Opin Neurobiol. 1 April 2013;23(2):250-4.
7. Ellis AW, Young AW. Human Cognitive Neuropsychology: A Textbook With Readings. Psychology Press; 2013. 694 p.
8. Terradillos E, López-Higes R. Guía de intervención logopédica en las afasias. 2016.
9. Berthier ML, Green C, Lara JP, Higueras C, Barbancho MA, Dávila G, et al. Memantine and constraint-induced aphasia therapy in chronic post stroke aphasia. Ann Neurol. May 2009;65(5):577-85.
10. Paniagua PJ. El entorno como sistema de comunicación [Internet]. Logocerebral. 2018 [cited 7 March 2018]. Available: http://logocerebral.es/entorno-sistema-comunicacion/