Changes in writing processes caused by post-stroke aphasia or low-grade glioma

Background: Writing is a cognitively and linguistically complex task, therefore sensitive to impairment caused by the presence and surgical removal of low-grade glioma or presence of post-stroke aphasia. Purposes: The overall aim of the thesis was to investigate the changes in writing processes, text characteristics and spelling caused by post-stroke aphasia or low-grade glioma. Methods: In study I, 20 consecutive participants with presumed low grade glioma wrote a copytask and a narrative and were tested with test of spoken lexical retrieval before and three months after tu-mour resection. The aim of the study was to investigate writing fluency before and after surgery and whether writing fluency was related to oral lexical re-trieval difficulties. In study II, the 15 participants with aphasia and a matched reference group wrote two narrative texts and were tested with dictation tests. Texts characteristics and aspects of the writing process were compared be-tween groups and relations between different writing processes were investi-gated for both groups. Relations between spelling in text and dictation tests were examined for the study group. In study III, the aim was to investigate the lexical features of two types of narrative texts, and the words with errors, writ-ten by 16 participants with aphasia and compare to texts written by a matched reference group. Corpus linguistic analysis methods were used. In study IV, 16 participants with aphasia wrote a word dictation test and were tested for phonological de-coding, reading ability and phonological spelling. Spelling ability and editing was analysed and related to reading and phonological abil-ities. The writing tasks in all studies were written in a keystroke logging pro-gram to enable analysis of the texts as well as the writing process behind the texts. Results and conclusions: I: Aspects of writing fluency were affected both before and after surgery but typing speed was an important factor behind the pre-surgery differences. A decline in overall productivity and an increase in pauses before words after surgery could be related to a lexical deficit. II: All aspects of productivity in text writing were affected for the group with apha-sia. There was a relation between editing and productivity for the persons with aphasia, but not for the reference group. Scores in spelling tests cannot predict spelling in free texts. III: Texts written by persons with aphasia contained a less varied vocabulary and they tended to avoid using long words. The mis- 6 spelled words were more likely to be content words, long words and uncom-mon words for the persons with aphasia than for the reference group. Lexical features in text writing were affected by aphasia, but was dependent on the type of text writing task. IV: The most common error type was omission of letter(s) and there was evidence of aphasia specific writing errors. Both spelling and editing difficulty was related to word frequency and word length. Successful editing was related to phonological spelling scores, but not to pho-nological de-coding or reading ability. Specific editing strategies could be identified