British Journal of Disorders of Communication, 25, 45-60 (1990) @The College of Speech Therapists, London
45
The remediation of conduction aphasia via sentence repetition: A case study Susan E. Kohn, and Katherine L. Smith Neurolinguistics Laboratory, Institute of Health Professions, Massachusetts General Hospital, USA
Joan Kelly Arsenault Department of Speech-Language Pathology, Massachusetts General Hospital, USA
ABSTRACT
Repetition is viewed typically as a primary deficit in conduction aphasia. Consequently, repetition is considered to be a target of treatment, as opposed to an approach to treatment for this syndrome. However, our experience with a conduction aphasic who had greater speech fluency in repetition than in conversation encouraged us to develop a treatment programme based on sentence repetition. The treatment programme has three components: ( I ) a pre-/post-test of sentence repetition; (2) the treatment component, in which a new set of sentences is introduced each week in outpatient therapy for daily repetition; (3) analysis of verbal picture description prior to and following treatment as an independent language measure. The patient CMparticipated in 2 months of sentence repetition treatment, after which he displayed improvement in both sentence repetition and picture description. The reasons for such improvement and the general utility of the treatment programme are discussed. Key words: conduction aphasia, remediation, repetition.
INTRODUCTION
Repetition is typically viewed as a primary deficit in conduction aphasia. Consequently, repetition is usually considered to be a target of treatment, as opposed to an approach to treatment, for this syndrome (Simmons, 1983; Wertz, 1987). However, our experiences with one conduction aphasic (CM) encouraged us to break with this tradition and use sentence repetition as a treatment technique. CM was a good candidate for piloting a new treatment programme for conduction aphasia, insofar as he fulfilled two basic requirements typically cited as necessary for evaluating treatment programmes. First, improvement during the new treatment programme could not be attributed to a non-specific
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treatment effect (Byng & Coltheart, 1986; Howard, 1986), because he had been involved in outpatient speech-language therapy for many months prior to the new programme. Secondly, improvements made on the new treatment programme could not be attributed to some sort of spontaneous recovery (Byng & Coltheart, 1986; Howard, 1986), because he had plateaued in therapy prior to the new programme. CM was introduced into the new treatment programme approximately 7 months after suffering a left-sided cerebrovascular accident. At this time, he was diagnosed as a moderate-to-severe conduction aphasic on the basis of his markedly impaired repetition for words and sentences, in combination with relatively spared auditory comprehension. In addition, his spontaneous speech contained the dysfluencies and numerous phonemic (or literal) paraphasias that are typical of conduction aphasia. Of interest for the current study was that he seemed to display greater speech fluency (i.e. longer sequences of words with fewer phonemic errors) during sentence repetition than during conversation. In conversation, CM consistently attempted to correct his phonemic paraphasias, even when errors were so minimal that communication was not impaired. These frequent attempts at error correction resulted in the production of even more phonemic paraphasias and numerous word fragments (or extraneous syllables), giving his speech a hesitant, stuttering-like quality. Moreover, by focusing on the accurate production of individual words, CM would often become ‘derailed’ in conversation. By contrast, when a spoken sentence was presented to CM for repetition, he tended to produce longer sequences of words and spend less effort correcting phonemic errors. Because the difference between CM’s spontaneous speech and repetition seemed to be one of degree, we surmised that the source of CM’s output difficulties in both contexts was basically the same, but that repetition was aided by the acoustic model provided by this task. We viewed his greater dysfluency in spontaneous speech as being due to a greater tendency to attempt error correction in this context. By basing a treatment programme on sentence repetition (i.e. the context in which CM’s speech was the most fluent), we hoped to reinforce the prosodic experience of producing complete sentences. Additionally, we expected that improvement would carry over to his spontaneous speech because of an increased motivation to continue speaking without correcting errors. These assumptions were based on two theoretical notions: 1. Conduction aphasia can involve a general output deficit in phonemic programming (Kohn, 1984, 1989; see Discussion). Thus, we would expect carry-over of improvement from repetition to spontaneous speech because the same underlying deficit is responsible for speech errors in both contexts.
2. Normal auditory comprehension involves a working memory system that automatically and obligatorily stores a temporary phonological trace of the auditory stimulus (i.e. access to the ‘phonological non-articulatory short-term store’), which, in turn, can be used for rehearsal (i.e. utilization of the ‘articulatory loop’; Vallar & Baddeley, 1984a, b). Thus, the working
REMEDIATION OF CONDUCTION APHASIA
47
memory system associated with auditory input provides phonological information that could help CM to programme his utterances. In designing the treatment programme, there were four basic requirements. First, CM’s level of sentence repetition needed to be assessed prior to and following therapeutic intervention (Byng & Coltheart, 1986). For this requirement, we constructed a pre-/post-test of sentence repetition composed of 30 sentences that varied along variables known to affect performance in aphasia (i.e. number of syllables, number of words and degree of semantic content). Secondly, treatment materials were needed. For this requirement, we constructed sets of 20 sentences that were introduced weekly in outpatient therapy sessions and practised daily at home and that were gradually increased in difficulty according to CM’s progress. For the third and fourth requirements, we used the same test. These requirements were as follows: To determine objectively whether there was any carry-over of improvement in sentence repetition to another speech context involving sentence production 2. To document that CM had indeed plateaued in his production of connected speech prior to the treatment programme (Byng & Coltheart, 1986). 1.
For both requirements, multiple descriptions of the Cookie Theft picture from the Boston Diagnostic Aphasia Exam (BDAE; Goodglass & Kaplan, 1983) were analysed for their ‘communicative efficiency’ (Yorkston & Beukelman, 1977; see Methods). CM participated in 2 months of sentence repetition treatment, during which time he made notable gains in speech. These results are presented to document his improvement and to consider the potential of this treatment programme to help similar aphasic patients. METHODS
Case History GM is a 74-year-old, right-handed male. Before retiring, and just prior to his first stroke, he worked as a patent attorney at the level of vice-president for a large company known for the development of innovative photographic equipment. CM was in good health until May 4, 1981, when he suffered a left-sided cerebrovascular accident. At this time, he presented with a sudden onset of aphasia characterised by incomprehensible, hesitant speech and an inability to read and write. No other problems were noted. He is said to have recovered his speech soon after this episode; the exact time frame is unknown. CM remained basically healthy until July 4, 1986, when he awoke in the morning with problems similar to those described above. He was unable to speak intelligibly, nor could he read and write. A mild right hemiparesis was present and subsequently resolved. On December 11, 1986, CM experienced a sudden worsening of his speech. At this time, his speech was said to contain few understandable words.
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Difficulty in repeating two-syllable words and in naming was noted. Auditory comprehension was impaired, but was superior to oral production. He could follow simple one-step commands when spoken, but not when written. Right-left orientation and buccofacial and limb praxis were intact. He could perform simple written calculations and some colour naming. As before, a mild right hemiparesis was present. At the time of his final stroke, CM had been participating in outpatient speech-language therapy twice a week for 7 months. He was hospitalised only one day for this stroke and, upon discharge, resumed his speech-language therapy up to and during the experimental treatment programme. Computerised tomographic (CT) scans, performed the day of or day after each stroke, revealed infarction in the distribution of the left middle cerebral artery. Lesion was restricted to the temporoparietal area, primarily affecting both lips of the sylvian fissure posteriorly. A formal language evaluation performed in July, 1987, 7 months following his final stroke and the point at which we first assessed CM for the treatment programme, revealed a pattern of deficits consistent with a diagnosis of a moderate-to-severe conduction aphasia. He displayed moderate deficits in verbal expression and mild deficits in auditory comprehension, reading comprehension and writing. His spontaneous speech appeared to be grammatically complete, but was typically ‘derailed’ by phonemic paraphasias and conduites d’approche. As a result, his speech had a marked dysfluent quality. CM exhibited moderate naming difficulty, especially given his level of education: he named correctly 46/60 pictures on the Boston Naming Test (Kaplan, Goodglass & Weintraub, 1983), which represents more than two standard deviations below the mean for normal performance (Nicholas, Brookshire, MacLennan, Schumacher & Porrazzo, 1989). Marked repetition impairment, especially for sentences, was documented by his performance on the repetition subtests of the BDAE (7/10 words, 418 high probability sentences, and 0/8 low probability sentences). CM’s oral reading of single words was similar to his abilitiy to repeat single words (BDAE Word Reading: 7/10). Across all production tests, errors were almost exclusively phonemic paraphasias. Essentially intact auditory comprehension was demonstrated by his ability to understand syntactically complex sentences, as revealed by his perfect scores on the supplementary language test of the BDAE (4/4 on both the Passive Subject-Object Discrimination and the Comprehension of Possessive Relationship subtests, 2/2 on the Subject of Verb Complement subtest, and 3/3 on the Manipulation of Verb Tense subtest). CM performed two-step commands without difficulty, but exhibited difficulty following three-step commands. Reading comprehension was intact for sentences and short paragraphs, as assessed by the Reading Comprehension Battery for Aphasia (Lapointe & Horner, 1979). He obtained perfect scores on all but three of the subtests (on both Functional Reading and Synonyms he received a score of 9/10, and on Paragraph Picture he received 7/10). CM wrote with his dominant right hand with good legibility. Both monosyllabic and multisyllabic words were written accurately, and he was able to write simple sentences with correct semantics and syntax.
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This clinical profile fits well with a diagnosis of conduction aphasia. Whilst there are some superficial similarities to the performance profile that is associated with apraxia of speech (compare Kent & McNeil, 1987), this latter diagnosis can be clearly ruled out. CM displayed none of the signs of difficulty programming the position of speech muscles and sequencing those muscle movements that are associated with apraxia of speech. For example, there was no groping for accurate articulatory placement and no prosodic disturbance (compare Wertz, 1978). Sentence Repetition Treatment Programme
As previously mentioned, the treatment programme is comprised of three basic components: (1) pre-/post-test of sentence repetition, (2) Cookie Theft descriptions, and (3) treatment sessions.
Pre-/Post-test of Sentence Repetition. The pre-/post-test was developed to establish CM's level of sentence repetition prior to and following the treatment component. More specifically, the pretest performance established the level of difficulty for the first treatment session, and established a baseline level of performance against which the post-test performance could be compared. The comparison between the pre-test and post-test performance provided information needed to judge directly the effectiveness of the treatment sessions. The pre-/post-test contains 30 sentences that differ along the following variables known to affect sentence repetition in aphasia: (1) number of words (from three to seven),' (2) number of syllables per word (from one to four) and (3) richness of semantic content. The last variable was manipulated by
Functor
Number of words
Substantive
Number of syllables:
1
1
2
3-4"
3
3
3
3
3
5
-
-
3
3
I
3
3
3
3
-----________________________________________._ ___________________----
'Only nouns were multisyllabic.
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KOHN, SMITH AND ARSENAULT
having two types of sentences: (1) sentences that contain functors and light verbs (i.e. main verbs that are similar to functors in that they carry little semantic meaning, such as ‘do’, ‘take’, ‘give’; Cattell, 1984)’ and (2) sentences that contain substantives (i.e. content words) for major lexical categories and few functors. The former will be referred to as ‘functor sentences’ and the latter will be referred as ‘substantive sentences’ (compare ‘She did that’ vs ‘Mary ate dinner’). (See Table 1 for the distribution of sentence types.) The performance was analysed both quantitatively and qualitatively. Quantitative measures included various ways of tabulating correct production: proportion of sentences totally correct, proportion of functors vs content words repeated correctly, and the longest contiguous string of words produced correctly. The qualitative analysis involved a tabulation of the dominant error types, which in this case were omissions (i.e. no attempt to produce target words) and phonemic paraphasias. A phonemic paraphasia was defined here as a phonemically distorted attempt that matched its target word in terms of at least a consonant cluster (e.g. sled+ ‘slight’), stressed vowel (e.g. kangaroo --t ‘goo’), or the onset and coda of a syllable (e.g. envelope ‘AoQ’). +
Cookie Theft description Performance on the Cookie Theft subtest from the BDAE was evaluated as an independent, standard measure of sentence-level speech production. Performance at two different times prior to treatment helped determine whether speech recovery had plateaued, and established a baseline against which performance following treatment could be evaluated. A comparison between this pre-treatment performance and a Cookie Theft description just following treatment was used to identify possible improvement in sentence production. In this way, picture description performance helped determine if improvements in sentence repetition had generalised to sentence production in another context. The Cookie Theft descriptions were evaluated by the Yorkston and Beukelman (1977) system developed specifically for quantifying verbal output on this BDAE subtest. Of their two ‘measures of communicative efficiency’, ‘the number of syllables per concept’ was judged as best suited for assessing CM’s level of efficiency in verbal communication, because it is a direct measure of how many syllables are used to express a concept. This measure of speech fluency seemed appropriate because the main purpose of the treatment programme was to improve CM’s communication by increasing his speech fluency. To obtain this measure, the total number of syllables produced is divided by the total number of concepts communicated. Yorkston and Beukelman compiled the list of acceptable concepts in the following way. They analysed the Cookie Theft descriptions of 31 normal speakers (mean age=33 years), and extracted a list of 68 different concepts that were mentioned by at least one speaker. Concepts were excluded if they were judged to be unrelated to the task (e.g. comments about the artistry of the drawing) or not directly communicated by the picture (e.g. the day of the week). The authors tested the inter-rater reliability of four judges and found that they were within a range of plus or minus one concept 95% of the time, and within a range of plus or minus 5 % for syllable counts.
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Their normal speakers communicated an average of 18 concepts, and used an average of 4.8 syllables to convey each concept. High-level non-fluent aphasics were very similar (4.9 syllables per concept) and high-level fluent aphasics required 7.8 syllables to express one concept. The aphasics were identified as high level by achieving a PICA score (Porch Index of Communicative Ability; Porch, 1971) between the 85th and 99th percentile. It is not clear how fluent and non-fluent were defined, but since Geschwind is cited it would seem that the former refer to Wernicke’s and anomic aphasics and the latter refer to Broca’s and mixed anterior aphasics. In this way, CM, being dysfluent, should fall in between the scores for high-level fluent and non-fluent aphasics if he is high level, and improved communicative efficiency can occur with a reduction of the number of syllables and/or increase in the number of concepts. In calculating the syllable/concept count, all syllables were counted, regardless of whether they were exact repetitions, or correct vs incorrect syllables of appropriate vs inappropriate words. For example, his sequence for cookies[kn kari], cookie-- was analysed as representing five syllables. The only syllables that were ignored were those that were part of an aside or editorialisation (e.g. ‘that’s wrong’, ‘oh, no’). In most cases, the concepts were (eventually)produced without phonological errors. The few exceptions were attempts with only minor phonological distortion and where targets were easily identified from context (e.g. spilling -+ spooling). This method of characterising CM’s sentence-level speech production had a number of advantages. Both the Cookie Theft subtest and the Yorkston and Beukelman analyses are well known to clinicians and easy to understand and replicate. Also, the system of analysis appears to be a valid method for quantifying the communicative efficiency of connected speech, insofar as Yorkston and Beukelman found that it distinguishes normals from aphasics and correlates grossly with severity of verbal output as measured by the PICA. Treatment materials All treatment materials consisted of sentences for repetition. The first treatment session introduced sentences that were within and just beyond CM’s initial repetition ability, as determined by pre-test performance; sentence difficulty was increased gradually over successive sessions along the same variables as were included in the pre-/post-test (i.e. number of words, number of syllables per words and semantic content). Five sessions were constructed for CM, each with a unique set of 20 sentences. Recall that our goal was to increase CM’s speech fluency, rather than increase the accuracy of his word production. Accordingly, we were not interested in staying at a particular level of difficulty until CM had reached an accuracy level of 100%. Instead, we continued to increase the level of difficulty so that he would have to avoid correcting some phonemic paraphasias in order to approximate repetition of the complete sentence. The difficulty level was increased when his speech-language pathologist judged that CM’s tendency to ‘derail’ due to attempts at error correction had decreased from the previous treatment session. Session one contained three-word sentences, half of which were functor sentences (e.g. ‘He did that’, ‘She was here’) and half of which were substantive
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sentences (e.g. ‘Jane likes school’, ‘Tom played ball’). Because the only sentences that CM had repeated entirely correctly on the pre-test were all three of the three-word functor sentences, it was expected that in session 1 the functor sentences would present little difficulty for CM, whilst the substantive sentences would present a challenge. The first session proved to be more challenging than expected: only 50% of the functor sentences were repeated entirely correctly. Consequently, the difficulty level of session 2 was reduced so that it included two-word and threeword sentences. As with the first session, half of the sentences for each length were functor sentences and half were substantive sentences (e.g. ‘Where is he?’ vs ‘John ate’). In session 2, CM performed at our initial level of expectation for functor sentences (90% correct). Consequently, functor sentences were eliminated from successive sessions. The purpose of session 3 was to introduce gradually multisyllabic words: half the sentences contained one-syllable nouns and half contained a single two-syllable noun. In an attempt to vary systematically sentence structure, half the sentences had a noun-verb (N-V) structure (e.g. ‘The teacher quit’, ‘The boy ran’) and half had a N-V-N structure (e.g. ‘Dave writes books’ , ‘Lynn serves coffee’); this variable was evenly distributed among the sentence types. For the fourth and fifth (i.e. final) treatment sessions, a similar format was used as in session 3. Sentence length was increased to four words. Half of the sentences contained both a two-syllable and a one-syllable noun and the other half contained two two-syllable nouns. All of the sentences had an N-V-N structure. Among the sentences with a single two-syllable noun, five began with the two-syllable noun (e.g. ‘William plays the flute’) and five ended with the two-syllable noun (e.g. ‘Tom liked the office’). Each sentence contained a functor; for 10 of the sentences it was an auxiliary verb (e.g. ‘Beth has found subjects’), and for the other 10 it was a determiner (e.g. ‘Tonyshot the arrow’). (See Table 2 for a summary of the sentence types used across the treatment sessions.)
Sentence type Functor 1
1
2a
DATE OF SESSION
10 5 5
-
Sept. 21, 1987
3
10 5 5
-
Sept. 28, 1987
3
-
10
10
Oct. 19, 1987
4
-
-
20
Oct. 29, 1987
4
-
-
20
Nov. 5 , 1987
Number of syllables:
3 2
Number of words
Substantive
“Only nouns were multisyllabic.
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Procedure
Prior to beginning the repetition treatment programme, CM had been receiving outpatient speech-language therapy for 14 months. This therapy consisted of two weekly sessions of an hour in length, during which a variety of basic skills was targeted for treatment. CM continued with this therapy during the repetition treatment programme, except that now a portion of one session each week (usually less than half an hour) was allotted to the repetition treatment programme. The portion of outpatient therapy that did not involve repetition treatment focused on reading, writing and high-level auditory comprehension. It is also relevant to note that CM’s speech-language pathologist (the third author) remained the same throughout the course of his therapy. The pre-test and Cookie Theft subtest were administered in outpatient therapy in the session prior to the first session of sentence repetition treatment. The Cookie Theft subtest had also been administered in therapy 2 months prior to this date (see Table 3 for dates). For the administration of the pre-/ post-test, CM was instructed to repeat individual sentences after they were spoken by his speech-language pathologist. If needed, his speech-language pathologist presented the entire sentence a second time. The administration of the Cookie Theft subtest followed the standard administration as set forth in the BDAE. The treatment sessions followed, occurring between September 21 and November 5, 1987, inclusive (see Table 2). These sessions involved consecutive weeks, except between sessions 2 and 3 when CM was unable to come to therapy. During the sessions of sentence repetition treatment, CM’s speech-language pathologist read aloud each sentence and asked him to repeat it after her. As with the pre-/post-test, a sentence could be read aloud more than once by the speech-language pathologist. In contrast to the pre-/post-test, CM was now instructed at the beginning of each session, and periodically reminded throughout the session, to repeat as much of each sentence as possible without worrying about correcting errors. In this way, emphasis was placed on speech fluency, not on phonological accuracy. Given this orientation, we intentionally refrained from giving him immediate feedback about specific phonemic errors. CM was also instructed to repeat each week’s set of sentences at home with his wife on the days when he received no repetition treatment in outpatient therapy. He was instructed to practise repeating his treatment sentences only once on each of these days, and, as in outpatient treatment, not to labour over errors. To facilitate this home practice, CM’s wife was given a form with the week’s sentences and a chart to keep track of their work. She did not score the correctness of his performance, but only noted that a repetition had been attempted. This was done to further reduce CM’s tendency to correct errors. After approximately 2 months of treatment, CM was reassessed with the post-test and Cookie Theft subtest of the BDAE. At this point, further participation in the treatment programme was curtailed by a change in his medical condition, preventing the collection of longitudinal data posttreatment. All performance during the treatment programme in outpatient therapy was
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tape recorded for more accurate evaluation, and transcribed independently by two listeners (the first and second authors). The Yorkston and Beukelman coding of the Cookie Thefts was performed independently by the same two scorers. There were no disagreements on either transcription or scoring.
RESULTS Stability of Speech Prior to Treatment
CM’s performance on the BDAE Cookie Theft description clearly demonstrated that his speech recovery had plateaued prior to treatment. There was a high degree of similarity between his performance 2 months prior and 1 week prior to beginning the treatment sessions. CM had identical syllable/concept counts (Yorkston & Beukelman, 1977): not only were the proportions virtually identical, but so was the actual number of syllables and concepts (Table 3). Table 3: BDAE Cookie Theft description: syllables per concept. Date
No. of syllables
No. of concepts
No. of syllables per concept
July 17, 1987 Sept. 14, 1987 Nov. 23, 1987
128 130 107
12 13 16
10.7 10.0 6.7
Performance Prior to vs following Treatment
The comparison of CM’s performance on the pre- and post-test revealed a number of ways in which his sentence repetition had improved. While he showed only modest improvement in the proportion of sentences repeated entirely correctly [lo% vs 17%; McNemar’s test for significance of changes (Siegel, 1956): 2 = not significant] and an identical ability correctly to repeat functors (52% each time), he produced significantly more content words correctly (i.e. nouns and verbs) in his sentences following treatment (29% correct pre-test vs 41 Yo correct post-test; McNemar’s x2= 7.006, P < 0.009). In addition, CM was unable to repeat any three-to-four-syllable (content) words on the pre-test, but repeated 28% (y,) of these targets on the post-test (Fisher’s P < 0.024). CM’s increased ability to repeat correctly content words in sentences following treatment also resulted in his being able to repeat longer, contiguous strings of words within the sentences. In comparing pre- and post-test performance with substantive sentences, there was a significant difference between the mean number of contiguous words produced correctly for each of the eight conditions of the pre-/post-test (see Table 1 for conditions; t-test = 2.86, d.f. = 7, P
45
The remediation of conduction aphasia via sentence repetition: A case study Susan E. Kohn, and Katherine L. Smith Neurolinguistics Laboratory, Institute of Health Professions, Massachusetts General Hospital, USA
Joan Kelly Arsenault Department of Speech-Language Pathology, Massachusetts General Hospital, USA
ABSTRACT
Repetition is viewed typically as a primary deficit in conduction aphasia. Consequently, repetition is considered to be a target of treatment, as opposed to an approach to treatment for this syndrome. However, our experience with a conduction aphasic who had greater speech fluency in repetition than in conversation encouraged us to develop a treatment programme based on sentence repetition. The treatment programme has three components: ( I ) a pre-/post-test of sentence repetition; (2) the treatment component, in which a new set of sentences is introduced each week in outpatient therapy for daily repetition; (3) analysis of verbal picture description prior to and following treatment as an independent language measure. The patient CMparticipated in 2 months of sentence repetition treatment, after which he displayed improvement in both sentence repetition and picture description. The reasons for such improvement and the general utility of the treatment programme are discussed. Key words: conduction aphasia, remediation, repetition.
INTRODUCTION
Repetition is typically viewed as a primary deficit in conduction aphasia. Consequently, repetition is usually considered to be a target of treatment, as opposed to an approach to treatment, for this syndrome (Simmons, 1983; Wertz, 1987). However, our experiences with one conduction aphasic (CM) encouraged us to break with this tradition and use sentence repetition as a treatment technique. CM was a good candidate for piloting a new treatment programme for conduction aphasia, insofar as he fulfilled two basic requirements typically cited as necessary for evaluating treatment programmes. First, improvement during the new treatment programme could not be attributed to a non-specific
46
KOHN, SMITH AND ARSENAULT
treatment effect (Byng & Coltheart, 1986; Howard, 1986), because he had been involved in outpatient speech-language therapy for many months prior to the new programme. Secondly, improvements made on the new treatment programme could not be attributed to some sort of spontaneous recovery (Byng & Coltheart, 1986; Howard, 1986), because he had plateaued in therapy prior to the new programme. CM was introduced into the new treatment programme approximately 7 months after suffering a left-sided cerebrovascular accident. At this time, he was diagnosed as a moderate-to-severe conduction aphasic on the basis of his markedly impaired repetition for words and sentences, in combination with relatively spared auditory comprehension. In addition, his spontaneous speech contained the dysfluencies and numerous phonemic (or literal) paraphasias that are typical of conduction aphasia. Of interest for the current study was that he seemed to display greater speech fluency (i.e. longer sequences of words with fewer phonemic errors) during sentence repetition than during conversation. In conversation, CM consistently attempted to correct his phonemic paraphasias, even when errors were so minimal that communication was not impaired. These frequent attempts at error correction resulted in the production of even more phonemic paraphasias and numerous word fragments (or extraneous syllables), giving his speech a hesitant, stuttering-like quality. Moreover, by focusing on the accurate production of individual words, CM would often become ‘derailed’ in conversation. By contrast, when a spoken sentence was presented to CM for repetition, he tended to produce longer sequences of words and spend less effort correcting phonemic errors. Because the difference between CM’s spontaneous speech and repetition seemed to be one of degree, we surmised that the source of CM’s output difficulties in both contexts was basically the same, but that repetition was aided by the acoustic model provided by this task. We viewed his greater dysfluency in spontaneous speech as being due to a greater tendency to attempt error correction in this context. By basing a treatment programme on sentence repetition (i.e. the context in which CM’s speech was the most fluent), we hoped to reinforce the prosodic experience of producing complete sentences. Additionally, we expected that improvement would carry over to his spontaneous speech because of an increased motivation to continue speaking without correcting errors. These assumptions were based on two theoretical notions: 1. Conduction aphasia can involve a general output deficit in phonemic programming (Kohn, 1984, 1989; see Discussion). Thus, we would expect carry-over of improvement from repetition to spontaneous speech because the same underlying deficit is responsible for speech errors in both contexts.
2. Normal auditory comprehension involves a working memory system that automatically and obligatorily stores a temporary phonological trace of the auditory stimulus (i.e. access to the ‘phonological non-articulatory short-term store’), which, in turn, can be used for rehearsal (i.e. utilization of the ‘articulatory loop’; Vallar & Baddeley, 1984a, b). Thus, the working
REMEDIATION OF CONDUCTION APHASIA
47
memory system associated with auditory input provides phonological information that could help CM to programme his utterances. In designing the treatment programme, there were four basic requirements. First, CM’s level of sentence repetition needed to be assessed prior to and following therapeutic intervention (Byng & Coltheart, 1986). For this requirement, we constructed a pre-/post-test of sentence repetition composed of 30 sentences that varied along variables known to affect performance in aphasia (i.e. number of syllables, number of words and degree of semantic content). Secondly, treatment materials were needed. For this requirement, we constructed sets of 20 sentences that were introduced weekly in outpatient therapy sessions and practised daily at home and that were gradually increased in difficulty according to CM’s progress. For the third and fourth requirements, we used the same test. These requirements were as follows: To determine objectively whether there was any carry-over of improvement in sentence repetition to another speech context involving sentence production 2. To document that CM had indeed plateaued in his production of connected speech prior to the treatment programme (Byng & Coltheart, 1986). 1.
For both requirements, multiple descriptions of the Cookie Theft picture from the Boston Diagnostic Aphasia Exam (BDAE; Goodglass & Kaplan, 1983) were analysed for their ‘communicative efficiency’ (Yorkston & Beukelman, 1977; see Methods). CM participated in 2 months of sentence repetition treatment, during which time he made notable gains in speech. These results are presented to document his improvement and to consider the potential of this treatment programme to help similar aphasic patients. METHODS
Case History GM is a 74-year-old, right-handed male. Before retiring, and just prior to his first stroke, he worked as a patent attorney at the level of vice-president for a large company known for the development of innovative photographic equipment. CM was in good health until May 4, 1981, when he suffered a left-sided cerebrovascular accident. At this time, he presented with a sudden onset of aphasia characterised by incomprehensible, hesitant speech and an inability to read and write. No other problems were noted. He is said to have recovered his speech soon after this episode; the exact time frame is unknown. CM remained basically healthy until July 4, 1986, when he awoke in the morning with problems similar to those described above. He was unable to speak intelligibly, nor could he read and write. A mild right hemiparesis was present and subsequently resolved. On December 11, 1986, CM experienced a sudden worsening of his speech. At this time, his speech was said to contain few understandable words.
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Difficulty in repeating two-syllable words and in naming was noted. Auditory comprehension was impaired, but was superior to oral production. He could follow simple one-step commands when spoken, but not when written. Right-left orientation and buccofacial and limb praxis were intact. He could perform simple written calculations and some colour naming. As before, a mild right hemiparesis was present. At the time of his final stroke, CM had been participating in outpatient speech-language therapy twice a week for 7 months. He was hospitalised only one day for this stroke and, upon discharge, resumed his speech-language therapy up to and during the experimental treatment programme. Computerised tomographic (CT) scans, performed the day of or day after each stroke, revealed infarction in the distribution of the left middle cerebral artery. Lesion was restricted to the temporoparietal area, primarily affecting both lips of the sylvian fissure posteriorly. A formal language evaluation performed in July, 1987, 7 months following his final stroke and the point at which we first assessed CM for the treatment programme, revealed a pattern of deficits consistent with a diagnosis of a moderate-to-severe conduction aphasia. He displayed moderate deficits in verbal expression and mild deficits in auditory comprehension, reading comprehension and writing. His spontaneous speech appeared to be grammatically complete, but was typically ‘derailed’ by phonemic paraphasias and conduites d’approche. As a result, his speech had a marked dysfluent quality. CM exhibited moderate naming difficulty, especially given his level of education: he named correctly 46/60 pictures on the Boston Naming Test (Kaplan, Goodglass & Weintraub, 1983), which represents more than two standard deviations below the mean for normal performance (Nicholas, Brookshire, MacLennan, Schumacher & Porrazzo, 1989). Marked repetition impairment, especially for sentences, was documented by his performance on the repetition subtests of the BDAE (7/10 words, 418 high probability sentences, and 0/8 low probability sentences). CM’s oral reading of single words was similar to his abilitiy to repeat single words (BDAE Word Reading: 7/10). Across all production tests, errors were almost exclusively phonemic paraphasias. Essentially intact auditory comprehension was demonstrated by his ability to understand syntactically complex sentences, as revealed by his perfect scores on the supplementary language test of the BDAE (4/4 on both the Passive Subject-Object Discrimination and the Comprehension of Possessive Relationship subtests, 2/2 on the Subject of Verb Complement subtest, and 3/3 on the Manipulation of Verb Tense subtest). CM performed two-step commands without difficulty, but exhibited difficulty following three-step commands. Reading comprehension was intact for sentences and short paragraphs, as assessed by the Reading Comprehension Battery for Aphasia (Lapointe & Horner, 1979). He obtained perfect scores on all but three of the subtests (on both Functional Reading and Synonyms he received a score of 9/10, and on Paragraph Picture he received 7/10). CM wrote with his dominant right hand with good legibility. Both monosyllabic and multisyllabic words were written accurately, and he was able to write simple sentences with correct semantics and syntax.
REMEDIATION OF CONDUCTION APHASIA
49
This clinical profile fits well with a diagnosis of conduction aphasia. Whilst there are some superficial similarities to the performance profile that is associated with apraxia of speech (compare Kent & McNeil, 1987), this latter diagnosis can be clearly ruled out. CM displayed none of the signs of difficulty programming the position of speech muscles and sequencing those muscle movements that are associated with apraxia of speech. For example, there was no groping for accurate articulatory placement and no prosodic disturbance (compare Wertz, 1978). Sentence Repetition Treatment Programme
As previously mentioned, the treatment programme is comprised of three basic components: (1) pre-/post-test of sentence repetition, (2) Cookie Theft descriptions, and (3) treatment sessions.
Pre-/Post-test of Sentence Repetition. The pre-/post-test was developed to establish CM's level of sentence repetition prior to and following the treatment component. More specifically, the pretest performance established the level of difficulty for the first treatment session, and established a baseline level of performance against which the post-test performance could be compared. The comparison between the pre-test and post-test performance provided information needed to judge directly the effectiveness of the treatment sessions. The pre-/post-test contains 30 sentences that differ along the following variables known to affect sentence repetition in aphasia: (1) number of words (from three to seven),' (2) number of syllables per word (from one to four) and (3) richness of semantic content. The last variable was manipulated by
Functor
Number of words
Substantive
Number of syllables:
1
1
2
3-4"
3
3
3
3
3
5
-
-
3
3
I
3
3
3
3
-----________________________________________._ ___________________----
'Only nouns were multisyllabic.
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having two types of sentences: (1) sentences that contain functors and light verbs (i.e. main verbs that are similar to functors in that they carry little semantic meaning, such as ‘do’, ‘take’, ‘give’; Cattell, 1984)’ and (2) sentences that contain substantives (i.e. content words) for major lexical categories and few functors. The former will be referred to as ‘functor sentences’ and the latter will be referred as ‘substantive sentences’ (compare ‘She did that’ vs ‘Mary ate dinner’). (See Table 1 for the distribution of sentence types.) The performance was analysed both quantitatively and qualitatively. Quantitative measures included various ways of tabulating correct production: proportion of sentences totally correct, proportion of functors vs content words repeated correctly, and the longest contiguous string of words produced correctly. The qualitative analysis involved a tabulation of the dominant error types, which in this case were omissions (i.e. no attempt to produce target words) and phonemic paraphasias. A phonemic paraphasia was defined here as a phonemically distorted attempt that matched its target word in terms of at least a consonant cluster (e.g. sled+ ‘slight’), stressed vowel (e.g. kangaroo --t ‘goo’), or the onset and coda of a syllable (e.g. envelope ‘AoQ’). +
Cookie Theft description Performance on the Cookie Theft subtest from the BDAE was evaluated as an independent, standard measure of sentence-level speech production. Performance at two different times prior to treatment helped determine whether speech recovery had plateaued, and established a baseline against which performance following treatment could be evaluated. A comparison between this pre-treatment performance and a Cookie Theft description just following treatment was used to identify possible improvement in sentence production. In this way, picture description performance helped determine if improvements in sentence repetition had generalised to sentence production in another context. The Cookie Theft descriptions were evaluated by the Yorkston and Beukelman (1977) system developed specifically for quantifying verbal output on this BDAE subtest. Of their two ‘measures of communicative efficiency’, ‘the number of syllables per concept’ was judged as best suited for assessing CM’s level of efficiency in verbal communication, because it is a direct measure of how many syllables are used to express a concept. This measure of speech fluency seemed appropriate because the main purpose of the treatment programme was to improve CM’s communication by increasing his speech fluency. To obtain this measure, the total number of syllables produced is divided by the total number of concepts communicated. Yorkston and Beukelman compiled the list of acceptable concepts in the following way. They analysed the Cookie Theft descriptions of 31 normal speakers (mean age=33 years), and extracted a list of 68 different concepts that were mentioned by at least one speaker. Concepts were excluded if they were judged to be unrelated to the task (e.g. comments about the artistry of the drawing) or not directly communicated by the picture (e.g. the day of the week). The authors tested the inter-rater reliability of four judges and found that they were within a range of plus or minus one concept 95% of the time, and within a range of plus or minus 5 % for syllable counts.
REMEDIATION OF CONDUCTION APHASIA
51
Their normal speakers communicated an average of 18 concepts, and used an average of 4.8 syllables to convey each concept. High-level non-fluent aphasics were very similar (4.9 syllables per concept) and high-level fluent aphasics required 7.8 syllables to express one concept. The aphasics were identified as high level by achieving a PICA score (Porch Index of Communicative Ability; Porch, 1971) between the 85th and 99th percentile. It is not clear how fluent and non-fluent were defined, but since Geschwind is cited it would seem that the former refer to Wernicke’s and anomic aphasics and the latter refer to Broca’s and mixed anterior aphasics. In this way, CM, being dysfluent, should fall in between the scores for high-level fluent and non-fluent aphasics if he is high level, and improved communicative efficiency can occur with a reduction of the number of syllables and/or increase in the number of concepts. In calculating the syllable/concept count, all syllables were counted, regardless of whether they were exact repetitions, or correct vs incorrect syllables of appropriate vs inappropriate words. For example, his sequence for cookies[kn kari], cookie-- was analysed as representing five syllables. The only syllables that were ignored were those that were part of an aside or editorialisation (e.g. ‘that’s wrong’, ‘oh, no’). In most cases, the concepts were (eventually)produced without phonological errors. The few exceptions were attempts with only minor phonological distortion and where targets were easily identified from context (e.g. spilling -+ spooling). This method of characterising CM’s sentence-level speech production had a number of advantages. Both the Cookie Theft subtest and the Yorkston and Beukelman analyses are well known to clinicians and easy to understand and replicate. Also, the system of analysis appears to be a valid method for quantifying the communicative efficiency of connected speech, insofar as Yorkston and Beukelman found that it distinguishes normals from aphasics and correlates grossly with severity of verbal output as measured by the PICA. Treatment materials All treatment materials consisted of sentences for repetition. The first treatment session introduced sentences that were within and just beyond CM’s initial repetition ability, as determined by pre-test performance; sentence difficulty was increased gradually over successive sessions along the same variables as were included in the pre-/post-test (i.e. number of words, number of syllables per words and semantic content). Five sessions were constructed for CM, each with a unique set of 20 sentences. Recall that our goal was to increase CM’s speech fluency, rather than increase the accuracy of his word production. Accordingly, we were not interested in staying at a particular level of difficulty until CM had reached an accuracy level of 100%. Instead, we continued to increase the level of difficulty so that he would have to avoid correcting some phonemic paraphasias in order to approximate repetition of the complete sentence. The difficulty level was increased when his speech-language pathologist judged that CM’s tendency to ‘derail’ due to attempts at error correction had decreased from the previous treatment session. Session one contained three-word sentences, half of which were functor sentences (e.g. ‘He did that’, ‘She was here’) and half of which were substantive
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sentences (e.g. ‘Jane likes school’, ‘Tom played ball’). Because the only sentences that CM had repeated entirely correctly on the pre-test were all three of the three-word functor sentences, it was expected that in session 1 the functor sentences would present little difficulty for CM, whilst the substantive sentences would present a challenge. The first session proved to be more challenging than expected: only 50% of the functor sentences were repeated entirely correctly. Consequently, the difficulty level of session 2 was reduced so that it included two-word and threeword sentences. As with the first session, half of the sentences for each length were functor sentences and half were substantive sentences (e.g. ‘Where is he?’ vs ‘John ate’). In session 2, CM performed at our initial level of expectation for functor sentences (90% correct). Consequently, functor sentences were eliminated from successive sessions. The purpose of session 3 was to introduce gradually multisyllabic words: half the sentences contained one-syllable nouns and half contained a single two-syllable noun. In an attempt to vary systematically sentence structure, half the sentences had a noun-verb (N-V) structure (e.g. ‘The teacher quit’, ‘The boy ran’) and half had a N-V-N structure (e.g. ‘Dave writes books’ , ‘Lynn serves coffee’); this variable was evenly distributed among the sentence types. For the fourth and fifth (i.e. final) treatment sessions, a similar format was used as in session 3. Sentence length was increased to four words. Half of the sentences contained both a two-syllable and a one-syllable noun and the other half contained two two-syllable nouns. All of the sentences had an N-V-N structure. Among the sentences with a single two-syllable noun, five began with the two-syllable noun (e.g. ‘William plays the flute’) and five ended with the two-syllable noun (e.g. ‘Tom liked the office’). Each sentence contained a functor; for 10 of the sentences it was an auxiliary verb (e.g. ‘Beth has found subjects’), and for the other 10 it was a determiner (e.g. ‘Tonyshot the arrow’). (See Table 2 for a summary of the sentence types used across the treatment sessions.)
Sentence type Functor 1
1
2a
DATE OF SESSION
10 5 5
-
Sept. 21, 1987
3
10 5 5
-
Sept. 28, 1987
3
-
10
10
Oct. 19, 1987
4
-
-
20
Oct. 29, 1987
4
-
-
20
Nov. 5 , 1987
Number of syllables:
3 2
Number of words
Substantive
“Only nouns were multisyllabic.
REMEDIATION OF CONDUCTION APHASIA
53
Procedure
Prior to beginning the repetition treatment programme, CM had been receiving outpatient speech-language therapy for 14 months. This therapy consisted of two weekly sessions of an hour in length, during which a variety of basic skills was targeted for treatment. CM continued with this therapy during the repetition treatment programme, except that now a portion of one session each week (usually less than half an hour) was allotted to the repetition treatment programme. The portion of outpatient therapy that did not involve repetition treatment focused on reading, writing and high-level auditory comprehension. It is also relevant to note that CM’s speech-language pathologist (the third author) remained the same throughout the course of his therapy. The pre-test and Cookie Theft subtest were administered in outpatient therapy in the session prior to the first session of sentence repetition treatment. The Cookie Theft subtest had also been administered in therapy 2 months prior to this date (see Table 3 for dates). For the administration of the pre-/ post-test, CM was instructed to repeat individual sentences after they were spoken by his speech-language pathologist. If needed, his speech-language pathologist presented the entire sentence a second time. The administration of the Cookie Theft subtest followed the standard administration as set forth in the BDAE. The treatment sessions followed, occurring between September 21 and November 5, 1987, inclusive (see Table 2). These sessions involved consecutive weeks, except between sessions 2 and 3 when CM was unable to come to therapy. During the sessions of sentence repetition treatment, CM’s speech-language pathologist read aloud each sentence and asked him to repeat it after her. As with the pre-/post-test, a sentence could be read aloud more than once by the speech-language pathologist. In contrast to the pre-/post-test, CM was now instructed at the beginning of each session, and periodically reminded throughout the session, to repeat as much of each sentence as possible without worrying about correcting errors. In this way, emphasis was placed on speech fluency, not on phonological accuracy. Given this orientation, we intentionally refrained from giving him immediate feedback about specific phonemic errors. CM was also instructed to repeat each week’s set of sentences at home with his wife on the days when he received no repetition treatment in outpatient therapy. He was instructed to practise repeating his treatment sentences only once on each of these days, and, as in outpatient treatment, not to labour over errors. To facilitate this home practice, CM’s wife was given a form with the week’s sentences and a chart to keep track of their work. She did not score the correctness of his performance, but only noted that a repetition had been attempted. This was done to further reduce CM’s tendency to correct errors. After approximately 2 months of treatment, CM was reassessed with the post-test and Cookie Theft subtest of the BDAE. At this point, further participation in the treatment programme was curtailed by a change in his medical condition, preventing the collection of longitudinal data posttreatment. All performance during the treatment programme in outpatient therapy was
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tape recorded for more accurate evaluation, and transcribed independently by two listeners (the first and second authors). The Yorkston and Beukelman coding of the Cookie Thefts was performed independently by the same two scorers. There were no disagreements on either transcription or scoring.
RESULTS Stability of Speech Prior to Treatment
CM’s performance on the BDAE Cookie Theft description clearly demonstrated that his speech recovery had plateaued prior to treatment. There was a high degree of similarity between his performance 2 months prior and 1 week prior to beginning the treatment sessions. CM had identical syllable/concept counts (Yorkston & Beukelman, 1977): not only were the proportions virtually identical, but so was the actual number of syllables and concepts (Table 3). Table 3: BDAE Cookie Theft description: syllables per concept. Date
No. of syllables
No. of concepts
No. of syllables per concept
July 17, 1987 Sept. 14, 1987 Nov. 23, 1987
128 130 107
12 13 16
10.7 10.0 6.7
Performance Prior to vs following Treatment
The comparison of CM’s performance on the pre- and post-test revealed a number of ways in which his sentence repetition had improved. While he showed only modest improvement in the proportion of sentences repeated entirely correctly [lo% vs 17%; McNemar’s test for significance of changes (Siegel, 1956): 2 = not significant] and an identical ability correctly to repeat functors (52% each time), he produced significantly more content words correctly (i.e. nouns and verbs) in his sentences following treatment (29% correct pre-test vs 41 Yo correct post-test; McNemar’s x2= 7.006, P < 0.009). In addition, CM was unable to repeat any three-to-four-syllable (content) words on the pre-test, but repeated 28% (y,) of these targets on the post-test (Fisher’s P < 0.024). CM’s increased ability to repeat correctly content words in sentences following treatment also resulted in his being able to repeat longer, contiguous strings of words within the sentences. In comparing pre- and post-test performance with substantive sentences, there was a significant difference between the mean number of contiguous words produced correctly for each of the eight conditions of the pre-/post-test (see Table 1 for conditions; t-test = 2.86, d.f. = 7, P
