Elsevier

Journal of Communication Disorders

Volume 54, March–April 2015, Pages 43-55
Journal of Communication Disorders

Case Report
The contrast between cueing and/or observation in therapy for verb retrieval in post-stroke aphasia

https://doi.org/10.1016/j.jcomdis.2015.01.003Get rights and content

Highlights

  • Verb naming significantly improved following semantic–phonological therapy.

  • Verb naming did not improve following action observation.

  • No improvement was observed for the control list of verbs.

Abstract

Background

Studies measuring treatment efficacy for post-stroke verb anomia are scarce. These studies mainly assessed the efficacy of three strategies: semantic, phonological and sensorimotor. Following these previous treatments, the performance of most participants improved on treated verbs, while improvement on untreated stimuli and tasks was inconsistent.

Aims

This study aimed to measure the effectiveness of a semantic–phonological strategy and a sensorimotor strategy for verb anomia in post-stroke aphasia.

Methods

A multiple baseline single-subject experimental study was conducted with two participants (9–37 years post-stroke). Four phases were completed: (1) background assessment, (2) baselines, (3) therapy, and (4) follow-up. Three equivalent lists of verbs were created for each participant and two of them were trained with a different strategy: action observation + semantic–phonological cues, action observation alone. The stimuli of the third list (control list) were not treated.

Results

The semantic–phonological cueing strategy led to a significant improvement. No improvement was observed after action observation. No generalization to untreated verbs was found.

Conclusions

Verb naming can be enhanced by semantic/phonological cueing. In addition, other studies (clinical, neuroimaging, etc.) are needed to document the effect of action observation for the treatment of verb anomia.

Learning outcomes: The reader will be able to (1) describe semantic–phonological therapies used in post-stroke verb anomia, (2) describe sensorimotor therapies used in post-stroke verb anomia, and (3) identify factors contributing to the efficacy of therapies to improve action naming in aphasia.

Introduction

Aphasia is an acquired language impairment following brain damage, such as stroke (Benson and Ardila, 1996, Verstichel and Cambier, 2005). Anomia is one of the most prevalent symptoms of aphasia and is experienced by almost everyone suffering from aphasia (Berndt et al., 2002, Goodglass, 1993, Nickels, 2002). Anomia is described as a difficulty retrieving words in spontaneous speech or structured tasks (e.g. picture naming, sentence completion) (Goodglass & Wingfield, 1997).

According to cognitive models of language and speech production (e.g. Caramazza, 1997, Dell et al., 1997, Levelt et al., 1999), word retrieval and word production result from the activation of specialized and interconnected components. These models represent the production of words as a staged process. The activation flow is initiated in a conceptual–semantic component and ends with the execution of articulation mechanisms. For picture naming, after visual analysis and recognition of the picture, access to the semantic features of the word to produce is required via the semantic system. The semantic system is the memory of meanings and conceptual information about, among other things, objects, people and words (Tulving, 1972). After this conceptual stage, the word form (“sound”) of the word to produce must be retrieved in the lexical output lexicon before articulation. According to this cognitive theoretical model of language production, one can describe different word retrieval impairments, each resulting from a functional deficit in one or more levels of the process (e.g. Caramazza & Miozzo, 1997). A deficit at the conceptual semantic level leads to the production of semantic paraphasias but is also characterized by difficulties in any task, linguistic or otherwise, requiring access to the meaning of a word or thing, including comprehension of concepts and words. A deficit functionally localized at the lexical phonological level rather leads to the production of semantic paraphasias, circumlocutions and phonological errors.

Anomia can affect all word classes. Most of the literature about treatment for post-stroke anomia focuses on nouns; anomia of verbs has received much less attention. As pointed out by Conroy, Sage, and Lambon Ralph (2006), this is surprising, considering the central role of verbs in sentence and speech production. Moreover, some studies report greater impairment for verbs than nouns in naming tasks for some patients (e.g. Bastiaanse and Jonkers, 1998, De Bleser and Kauschke, 2003, Marshall et al., 1998). Despite the importance of verb anomia, studies measuring treatment efficacy for verb retrieval in aphasia are scarce. In the few intervention studies that focused on verbs, semantic and phonological strategies were combined or used in isolation. With respect to semantic strategies, one of the treatments used consisted of an adaptation of semantic feature analysis (Boyle and Coelho, 1995, Ylvisaker and Szekeres, 1985), a treatment in which the participant is helped to generate semantic features of the target word. For verb anomia, participants have to generate semantic characteristics of action words (e.g. aim of the action, tools or body parts involved in its execution) in order to strengthen the semantic network of verbs. Using this strategy, Wambaugh and Ferguson (2007) observed a moderate improvement in action naming in an individual with semantic anomia, while Faroqi-Shah and Graham (2011) found an improvement in one patient but not in the other. Other semantic strategies, such as noun-verb associations (e.g. scissors/to cut) or judgments on sentences (e.g. Does the sentence “The dentist measures the door” make sense considering the dentist's job?), were also used in studies concerning the treatment of verb anomia (e.g. Edmonds et al., 2009, Webster et al., 2005). With these strategies, most participants improved but improvement on untreated stimuli and untreated tasks (i.e. generalization) was inconsistent. Only a few studies using in-depth semantic strategies reported generalization to control conditions (e.g. Edmonds et al., 2009, Wambaugh and Ferguson, 2007).

In other studies, semantic and phonological strategies were combined or compared (e.g. Conroy et al., 2009b, Conroy et al., 2009c, Conroy and Scowcroft, 2012, Edwards and Tucker, 2006, McCann and Doleman, 2011). Phonological strategies relate to cues/questions concerning the sound form of the target verb such as the first phoneme, first syllable, or number of syllables. Raymer et al. (2007) assessed the efficacy of a treatment combining repetition, phonological questions and semantic questions about actions. This treatment led to action naming improvement in five of the eight participants. The overall severity of the aphasia as well as the severity of the comprehension deficit was put forward to explain the absence of improvement in the three remaining participants. Wambaugh et al. (2001), Wambaugh, Cameron, Kalinyak-Fliszar, Nessler, and Wright (2004) and Raymer and Ellsworth (2002) also compared phonological and semantic cueing for verb retrieval. They showed that both strategies were equally effective in improving verb naming. However, the performance of one of the patients reported by Wambaugh et al. (2004) did not improve, a result attributed by the authors to the severity of the semantic impairment.

Overall, these results suggest that verb retrieval therapy using semantic and/or phonological strategies is generally effective for treated verbs. They also suggest that patients showing anomia due to semantic level impairment seem less responsive to treatment. Results remain inconsistent for untreated verbs (control condition) and untreated tasks.

Phonological and semantic therapies for verb naming are in line with those reported for noun naming. However, they do not explicitly take into account the dynamic component of verbs, a fact that may explain the inconsistencies in the results for efficacy with semantic/phonological approaches. To consider this specific nature of verbs, a growing number of studies focused on sensorimotor strategies (e.g. Raymer et al., 2006, Rodriguez et al., 2006) for the treatment of verb anomia. These studies postulated that executing the action or observing someone producing the movement associated with a verb could improve verb retrieval. This assumption can be related to the embodied cognition viewpoint (e.g. Barsalou, 1999, Gallese and Lakoff, 2005) according to which the meaning of a word is grounded in modal experiences. For example, in theories of embodied semantics for actions, the sensorimotor network involved in executing the action “to cut” would be activated when processing the concept “to cut” (Aziz-Zadeh and Damasio, 2008, Aziz-Zadeh et al., 2006). In line with this viewpoint, observing or executing an action would activate the sensorimotor network and could facilitate retrieval of the lexical form of the concept. Rose and Sussmilch (2008) compared the effectiveness of semantic cueing, gesture production and a combination of semantic cueing and gesture production strategies in three patients with anomia. All three strategies were effective for two patients with lexical–phonological level impairment. However, the combination of semantic cueing and gesture production was more effective in one of them. The performance of the third participant, who had semantic based verb retrieval impairment, did not improve, regardless of the strategy used. Boo and Rose (2011) also contrasted, among other things, repetition, semantic cueing and a combination of semantic cueing and gesture production in two patients with anomia (GF and PF). Immediately post-treatment, both improved following the semantic and the combined treatment. PF also improved following repetition. Improvement was maintained one month post-therapy following the combined treatment for GF while repetition and semantic treatment led to maintenance for PF.

The question of the motor aspects of verbs was addressed more closely in recent studies investigating the potential of action observation for verb retrieval. Marangolo et al. (2010) compared action observation, action observation plus execution of the action, and action observation plus execution of a meaningless movement, in six participants with aphasia. In the action observation therapy, participants had to observe the experimenter executing the action and then try to name it. In the action observation plus execution of the action therapy, the participant had to observe the experimenter executing the action, imitate the movement, and try to name the action. Finally, in the action observation plus execution of a meaningless movement approach, the participant had to observe the experimenter executing the action, execute an unrelated movement, and try to name the action. The participants did not receive any feedback or cues. The four participants with lexical–phonological based anomia improved equally following action observation and action observation plus execution of the action. Action observation plus execution of a meaningless movement did not lead to any improvement. The two participants with semantic based anomia did not improve for any of the three conditions. In 2012, Marangolo and her collaborators (Marangolo, Cipollari, Fiori, Razzano, & Caltagirone, 2012) extended their results by showing that action observation helps the retrieval of human action verbs only (e.g. dancing) when compared to non-human action verbs (e.g. barking). To explain the efficacy of action observation therapy, Marangolo et al., 2010, Marangolo et al., 2012 suggested that action observation therapy increased the activation of the sensory-motor representation of the verb and helped to retrieve the word form at the lexical level. Bonifazi et al. (2013) obtained results consistent with the two previous studies. Four participants improved in verb naming following observation of human actions while two participants with verb semantic deficits did not improve. In sum, studies concerning sensorimotor verb retrieval therapies generally found improvement in treated verbs for patients with anomia due to lexical–phonological impairment. Patients with semantic anomia presented different patterns of response to verb retrieval therapies. However, these previous studies on sensorimotor strategies did not allow comparison between action observation and classical linguistic strategies using phonological and semantic cueing. Moreover, none of them explicitly questioned the generalization of the effects of treatments to the comprehension of treated and untreated verbs. Such a generalization in comprehension would be a substantial support to sensorimotor strategies, which are based on the embodied cognition viewpoint. Indeed, the reactivation of action words, whose meaning are grounded in modal experiences, should lead to improvement in spoken production, but also in word comprehension.

The present study thus aimed to measure the effectiveness of a therapy for verb retrieval anomia in post-stroke aphasia. A semantic–phonological cueing strategy (action observation + feedback and cues) was measured and compared to a sensorimotor-only strategy (action observation alone). The outcomes address the specific efficacy of these strategies, as well as generalization of the effects of the treatment to naming of untreated verbs (control list of verbs) and comprehension of verbs. The main hypothesis was that the semantic–phonological cueing strategy would lead to greater improvement than the sensorimotor-only strategy, as cueing adds input when compared to observation alone. Generalization of naming improvement to comprehension of treated verbs was predicted, as improvement in naming may occur following improvement and/or consolidation of the semantic and/or lexical component of the verbs, also involved in comprehension processes. No generalization to untreated verbs (control condition) was expected as the type of treatment used in the present study (i.e. no in-depth semantic treatment as in the SFA studies, for example) usually leads to item-specific outcome.

Section snippets

Method

A multiple baseline single-subject experimental design with replication across 2 participants was used. This design allows participants’ individual data to be analyzed because results are not averaged across participants (Nickels, Howard, & Best, 2011). In such a methodological design, each participant is his/her own control. As pointed out by Schwartz and Dell (2010), heterogeneity among participants is therefore welcomed and response patterns can then be analyzed in order to better understand

Visual analysis

Fig. 1, Fig. 2 illustrate verb naming performance for each of the three lists in each phase of the protocol for P1 and P2.

Visual analysis of the graphs shows an increase in naming scores from baseline to the end of the treatment phase for the cued list for both participants. For P1, the number of verbs correctly named in the uncued list also tended to improve (by 10%) during the treatment phase. Concerning maintenance, P1 showed scores above baseline until 8 weeks after the end of treatment for

Discussion

In this study, the effectiveness of a therapy for verb anomia in post-stroke aphasia was assessed in two participants with chronic aphasia. An increasing cueing strategy (action observation followed by – if no or incorrect response – sentence to complete, first syllable, repetition) was compared to an uncued strategy (action observation with no feedback or cues), and a control condition (no treatment). As hypothesized, outcomes revealed the efficacy of the cueing strategy for the two

Acknowledgments

The first author was supported by a Vanier Canada Graduate Scholarship for her doctoral degree (Canadian Institutes of Health Research). The authors would like to thank the two participants and their family for participating in the present study.

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      Home therapy could be an interesting option for these people, allowing them to reach their maximum rehabilitation potential. Moreover, although clinicians usually assume that the greatest amount of recovery from aphasia primarily takes place during a spontaneous recovery period, occurring in the immediate period after stroke and lasting as long as one year, some studies provide evidence that people with aphasia can make significant improvements in response to treatment well over one year post-onset (e.g., Basso, Capitani, & Vignolo, 1979; Kertesz and McCabe, 1977; Routhier, Bier, & Macoir, 2015). Indeed, some researchers found that time post-onset was not related to response to treatment in chronic aphasia (Allen, Mehta, McClure, & Teasell, 2012; Moss & Nicholas, 2006).

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