Crossroads in aphasia rehabilitation

This thesis focusses on two types of aphasia rehabilitation, cognitive linguistic treatment (CLT) and AAC (Augmentative and Alternative Communication) training. In a study of the effect of nonlinguistic variables on the outcome of CLT, it was shown, that neuropsychological data contributed significantly to the prediction of verbal communicative ability after treatment. It is concluded that a neuropsychological assessment is needed in all aphasic patients before treatment is started. In a study of the efficacy of AAC in people with a severe aphasia, a computerised communication aid, TouchSpeak (TS), was developed and tested in 34 aphasic patients. 57 % of the participants used the device in everyday life scenarios and overall communicative abilities improved with TS training. The final chapter presents a new test for overall (verbal and nonverbal) communication in people with a severe aphasia. In a pilot group, patients with a severe aphasia showed large variation in overall scores. In addition, several communicative patterns could be described

Assessment and treatment of linguistic deficits in aphasic patients

Aphasia is a language disturbance caused by brain damage, usually a stroke. Aphasia has a large impact on a patient’s life, often turning everyday communicative situations into a struggle to understand and be understood. Improvement of these patients’ communicative ability in daily life is the main goal of aphasia therapy. The verbal communicative ability of aphasic patients may be disturbed by semantic (word meaning), phonological (word form) and/or syntactic (grammatical structure) deficits. Cognitive linguistic treatment aims to improve processing at the affected linguistic level, implicitly assuming that training of basic language skills will result in improved verbal communication. In this thesis, the relative impact of semantic and phonological deficits on verbal communication is explored. Furthermore, the results of both diagnostic and therapeutic studies in patients with aphasia after stroke are presented

The effect of lexical content on sentence production in nonfluent aphasia

Individuals with nonfluent aphasia are able to produce many words in isolation, but have great difficulty producing sentences. Most research to date has compared accuracy across different types of sentence structures, focussing on grammatical aspects that may be compromised in nonfluent aphasia. However, based on the premise that lexical elements activate their associated grammatical frames as well as vice versa, lexical content may also be of vital importance. For example, rapid access to lexical elements – particularly ones appearing early in the sentence - may be crucial, especially if the sentence plan is weakly activated or rapidly decaying. The current study investigated the effect of different aspects of lexical content on nonfluent aphasic sentence production. Five participants with nonfluent aphasia, four participants with fluent aphasia and eight controls completed two picture description tasks eliciting subject-verb-object sentences (e.g., the dog is chasing the fox). Based on existing evidence suggesting that common words are accessed more rapidly than rarer ones, Experiment 1 manipulated the frequency of sentence nouns, thereby varying their speed of lexical retrieval by varying the frequency of sentence nouns. Nonfluent participants' accuracy was consistently higher for sentences commencing with a high frequency subject noun, even when errors on those nouns were themselves excluded. This was not the case for the fluent participants. Experiment 2 manipulated the semantic relationship between subject and object nouns. Previous research suggests that phrases containing related words may be challenging for individuals with nonfluent aphasia, possibly because lexical representations are inadequately tied to appropriate structural representations. The nonfluent participants produced sentences less accurately when they contained related lexical items, even when those items were in different noun phrases. The fluent participants exhibited the opposite trend. Finally, the relationship between the patterns observed in Experiment 1 and 2 and lesion location in the aphasic participants was explored by analysing magnetic resonance scans. We discuss the implications of our findings for theoretical accounts of sentence production more generally, and of nonfluent aphasia in particular. More precisely, we propose that individuals with nonfluent aphasia are disproportionately reliant on activated lexical representations to drive the sentence generation process, an idea we call the Content Drives Structure (COST) hypothesis

Combined brain language connectivity and intraoperative neurophysiologic techniques in awake craniotomy for eloquent-area brain tumor resection

Speech processing can be disturbed by primary brain tumors (PBT). Improvement of presurgical planning techniques decrease neurological morbidity associated to tumor resection during awake craniotomy. The aims of this work were: 1. To perform Diffusion Kurtosis Imaging based tractography (DKI-tract) in the detection of brain tracts involved in language; 2. To investigate which factors contribute to functional magnetic resonance imaging (fMRI) maps in predicting eloquent language regional reorganization; 3. To determine the technical aspects of accelerometric (ACC) recording of speech during surgery. DKI-tracts were streamlined using a 1.5T magnetic resonance scanner. Number of tracts and fiber pathways were compared between DKI and standard Diffusion Tensor Imaging (DTI) in healthy subjects (HS) and PBT patients. fMRI data were acquired using task-specific and resting-state paradigms during language and motor tasks. After testing intraoperative fMRI’s influence on direct cortical stimulation (DCS) number of stimuli, graph-theory measures were extracted and analyzed. Regarding speech recording, ACC signals were recorded after evaluating neck positions and filter bandwidths. To test this method, language disturbances were recorded in patients with dysphonia and after applying DCS in the inferior frontal gyrus. In contrast, HS reaction time was recorded during speech execution. DKI-tract showed increased number of arcuate fascicle tracts in PBT patients. Lower spurious tracts were identified with DKI-tract. Intraoperative fMRI and DCS showed similar stimuli in comparison with DCS alone. Increased local centrality accompanied language ipsilateral and contralateral reorganization. ACC recordings showed minor artifact contamination when placed at the suprasternal notch using a 20-200 Hz filter bandwidth. Patients with dysphonia showed decreased amplitude and frequency in comparison with HS. ACC detected an additional 11% disturbances after DCS, and a shortening of latency within the presence of a loud stimuli during speech execution. This work improved current knowledge on presurgical planning techniques based on brain structural and functional neuroimaging connectivity, and speech recordingA função linguística do ser humano pode ser afetada pela presença de tumores cerebrais (TC) A melhoria de técnicas de planeamento pré-cirurgico diminui a morbilidade neurológica iatrogénica associada ao seu tratamento cirúrgico. O objetivo deste trabalho é: 1. Testar a fiabilidade da tractografia estimada por difusor de kurtose (tract-DKI), dos feixes cerebrais envolvidos na linguagem 2. Identificar os fatores que contribuem para o mapeamento linguagem por ressonância magnética funcional (RMf) na predição da neuroplasticidade. 3. Identificar aspetos técnicos do registo da linguagem por accelerometria (ACC). A DKI-tract foi estimada após realização de RM cerebral com 1.5T. O número e percurso das fibras foi avaliado. A RMf foi adquirida durante realização de tarefas linguísticas, motoras, e em repouso. Foi testada influência dos mapas de ativação calculados por RMf, no número de estímulos realizados durante a estimulação direta cortical (EDC) intraoperatória. Medidas de conectividade foram extraídas de regiões cerebrais. A posição e filtragem de sinal ACC foram estudadas após vocalização de palavras. O sinal ACC obtido em voluntários foi comparado com doentes disfónicos, após estimulação do giro inferior frontal, e após a adição de um estímulo sonoro perturbador durante vocalização. A tract-DKI estimou um elevado número de fascículos do feixe arcuato com menos falsos negativos. Os mapas linguísticos de RMf intraoperatória, não influenciou a EDC. Medidas de centralidade aumentaram após neuroplasticidade ipsilateral e contralateral. A posição supraesternal e a filtragem de sinal ACC entre 20-200Hz demonstrou menor ruido de contaminação. Este método identificou diminuição de frequência e amplitude em doentes com disfonia, 11% de erros linguísticos adicionais após estimulação e diminuição do tempo de latência quando presente o sinal sonoro perturbador. Este trabalho promoveu a utilização de novas técnicas no planeamento pré-cirúrgico do doente com tumor cerebral e alterações da linguagem através do estudo de conectividade estrutural, funcional e registo da linguagem