The role of neuropsychology in aphasia
The term aphasia refers to alterations in language and communication due to brain injury, although aphasia entails limitationsinall areas of a person’s life that go far beyond language problems. 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 ofpersons 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 itand are also influenced by it, such as working memory, executive functioning and memory, among others (1). Understanding this profile can be key to knowingwhat abilities have been preserved before startingrehabilitation.
In addition, neuropsychology is one of the fields responsible fordirectingthe different advances in neuroscience regarding language function and developing new methods for approaching rehabilitation, moving from asyndrome model or approachto a model based on language processes(2,3).
Neuropsychological assessment of aphasia
The framing model
One of the main requirements for neuropsychological assessment of languageis 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 modelproposes a syndrome classification but is insufficient to describe the language alterations present in individuals with aphasia, and thus, not very specific tobe used forassessmentand subsequent rehabilitation. Moreover, there are other models that can be more useful.
At the functional-anatomiclevel, the dual-stream modelproposed by Hickok and Poeppel (5) postulates two pathwaysthat are relevant tolanguage production and language comprehension. A dorsal stream (analogous to the Wernicke-Geschwind model) supports phonological and motor processing whereas a ventral streamdeals withauditory comprehension and is more involved insemantic 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 thecognitive 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 modelprovides afoundation for the developmentof a successful approach to aphasia treatment.
The key to designing a rehabilitation program, therefore, lies in theability todetectwhich 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 analyzingany errors exhibited by them.
PALPA (Psycholinguistic Assessments of Language Processing in Aphasia) is a clinical instrumentdesigned toassess 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 retrievesemantic information from pictures.
It should also be noted that, in most cases, an assessment should be conductedto determine how other cognitive functions may be affecting language in general or some process in particular.
It should not be forgotten that, in many cases, neuropsychological assessment goes beyondidentifyingimpairments; considering the effects of these difficultiesis 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 administrationof 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
On this basis, the approach to neuropsychological rehabilitation should focus on trainingtheimpaired processesidentifiedbya previous assessment. Methods of rehabilitation include classic techniques such as errorless learning and sentence/picture matching tasks (for example, associating sentence elements and sentenceorder with colors to train agrammatic patients). Having reached this point, it is clear that treatmentshould 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.
Finally, it should be noted that neuropsychological intervention in aphasia has been shown to be very effective in the year followingbrain injury,but has as well been proven to yield significant improvement at the chronic stage (9).
If you liked this post, you might find the following interesting as well:
- Cahana-Amitay D, Albert M. RedefiningRecoveryfromAphasia. Oxford, New York: Oxford UniversityPress; 2015. 296 p.
- Tremblay P, Dick AS. Broca and Wernicke are dead, ormovingpasttheclassicmodel of languageneurobiology. BrainLang. 1 November2016;162:60-71.
- Vega FC. Neurociencia del lenguaje: bases neurológicas e implicaciones clínicas [Internet]. Madrid: Panamericana; 2011 [cited 7 March 2018]. Available: https://dialnet.unirioja.es/servlet/libro?codigo=555469
- Geschwind N. Disconnexionsyndromes in animals and man. I. Brain J Neurol. June 1965;88(2):237-94.
- Hickok G, Poeppel D. Dorsal and ventral streams: a frameworkforunderstandingaspects of thefunctionalanatomy of language. Cognition. June 2004;92(1-2):67-99.
- Friederici AD, Gierhan SM. Thelanguagenetwork. CurrOpinNeurobiol. 1 April 2013;23(2):250-4.
- Ellis AW, Young AW. Human CognitiveNeuropsychology: A TextbookWithReadings. PsychologyPress; 2013. 694 p.
- Terradillos E, López-Higes R. Guía de intervención logopédica en las afasias. 2016.
- Berthier ML, Green C, Lara JP, Higueras C, Barbancho MA, Dávila G, et al. Memantine and constraint-inducedaphasiatherapy in chronicpoststrokeaphasia. Ann Neurol. May 2009;65(5):577-85.
- Paniagua PJ. El entorno como sistema de comunicación [Internet]. Logocerebral. 2018 [cited 7 March 2018]. Available: http://logocerebral.es/entorno-sistema-comunicacion/
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