Miet De Letter

Lateralized effects of subthalamic nucleus stimulation on different aspects of speech in Parkinson’s disease

In this report, we have analyzed the effects of left and right STN stimulation separately on different aspects of speech. Significant differences were found between left and right stimulation. It appears that selective left-sided stimulation has a profoundly negative effect on prosody, articulation and hence intelligibility. Right-sided stimulation does not display this side-effect. There is no significant difference in speech characteristics between bilateral stimulation on and off. We suggest that a balanced tuning of bilateral basal ganglia networks is necessary for speech, and that the left circuit is probably dominant.

Levodopa-induced modifications of prosody and comprehensibility in advanced Parkinson's disease as perceived by professional listeners

The prosodic aspects of hypokinetic dysarthria in Parkinsons disease (PD) have been the focus of numerous reports. Few data on the effects of levodopa on prosody, more specifically on the effects on the variability of prosodic characteristics such as pitch, loudness and speech rate, are available in advanced PD. The relation between these characteristics and comprehensibility is currently unknown. These topics are the focus of the present report. Ten patients with advanced PD were evaluated, with and without medication, by four speech‐language pathologists during a reading task. A significant improvement of variability in pitch and loudness was demonstrated after medication intake. Comprehensibility improved following medication administration. Results are compared with previous studies.

Cognate Effects and Executive Control in a Patient with Differential Bilingual Aphasia

We describe a case study of a French–Dutch bilingual patient with differential aphasia, showing clearly larger impairments in Dutch than in French. We investigated whether this differential impairment in both languages was due to selective damage to language-specific brain areas resulting in the “loss” of the language representation itself, or rather if it reflects an executive control deficit. We assessed cross-linguistic interactions (involving lexical activation in the most affected language) with cognates in a lexical decision (LD) task, and executive control using a flanker task. We used a generalized LD task (any word requires a “yes” response) and a selective LD task in the patients two languages (only words in a given target language require a “yes” response). The cognate data unveil a differential pattern in the three tasks, with a clear cognate facilitation effect in the generalized LD tasks and almost no cognate effect in the selective LD tasks. This implies that a more impaired language can still affect the processing of words in the best-preserved language, but only with low cross-language competition demands (generalized LD). Additionally, the flanker task showed a larger congruency effect for the patient compared with controls, indicating cognitive control difficulties. Together, these results support accounts of differential bilingual aphasia in terms of language-control difficulties.

Increased motor preparation activity during fluent single word production in DS: A correlate for stuttering frequency and severity.

Abnormal speech motor preparation is suggested to be a neural characteristic of stuttering. One of the neurophysiological substrates of motor preparation is the contingent negative variation (CNV). The CNV is an event-related, slow negative potential that occurs between two defined stimuli. Unfortunately, CNV tasks are rarely studied in developmental stuttering (DS). Therefore, the present study aimed to evaluate motor preparation in DS by use of a CNV task. Twenty five adults who stutter (AWS) and 35 fluent speakers (FS) were included. They performed a picture naming task while an electro-encephalogram was recorded. The slope of the CNV was evaluated at frontal, central and parietal electrode sites. In addition, a correlation analysis was performed with stuttering severity and frequency measures. There was a marked increase in CNV slope in AWS as compared to FS. This increase was observed over the entire scalp with respect to stimulus onset, and only over the right hemisphere with respect to lip movement onset. Moreover, strong positive correlations were found between CNV slope and stuttering frequency and severity. As the CNV is known to reflect the activity in the basal ganglia-thalamo-cortical-network, the present findings confirm an increased activation of this loop during speech motor preparation in stuttering. The more a person stutters, the more neurons of this cortical-subcortical network seem to be activated. Because this increased CNV slope was observed during fluent single word production, it is discussed whether or not this observation refers to a successful compensation strategy.

When will a stuttering moment occur? The determining role of speech motor preparation.

The present study aimed to evaluate whether increased activity related to speech motor preparation preceding fluently produced words reflects a successful compensation strategy in stuttering. For this purpose, a contingent negative variation (CNV) was evoked during a picture naming task and measured by use of electro-encephalography. A CNV is a slow, negative event-related potential known to reflect motor preparation generated by the basal ganglia-thalamo-cortical (BGTC) - loop. In a previous analysis, the CNV of 25 adults with developmental stuttering (AWS) was significantly increased, especially over the right hemisphere, compared to the CNV of 35 fluent speakers (FS) when both groups were speaking fluently (Vanhoutte et al., (2015) doi: 10.1016/j.neuropsychologia.2015.05.013). To elucidate whether this increase is a compensation strategy enabling fluent speech in AWS, the present analysis evaluated the CNV of 7 AWS who stuttered during this picture naming task. The CNV preceding AWS stuttered words was statistically compared to the CNV preceding AWS fluent words and FS fluent words. Though no difference emerged between the CNV of the AWS stuttered words and the FS fluent words, a significant reduction was observed when comparing the CNV preceding AWS stuttered words to the CNV preceding AWS fluent words. The latter seems to confirm the compensation hypothesis: the increased CNV prior to AWS fluent words is a successful compensation strategy, especially when it occurs over the right hemisphere. The words are produced fluently because of an enlarged activity during speech motor preparation. The left CNV preceding AWS stuttered words correlated negatively with stuttering frequency and severity suggestive for a link between the left BGTC - network and the stuttering pathology. Overall, speech motor preparatory activity generated by the BGTC - loop seems to have a determining role in stuttering. An important divergence between left and right hemisphere is hypothesized.

Speech characteristics one year after first Belgian facial transplantation

Facial transplantation has progressed over the past 8 years. We did the first Belgian facial transplantation by vascularized composite tissue allotransplantation and report the 1‐year follow‐up regarding speech and oromyofunctional behavior.

Sequential changes in motor speech across a levodopa cycle in advanced Parkinson's disease

Previous research has indicated that in Parkinsons disease (PD) some motor speech characteristics are changed by levodopa administration, while others are not. In advanced PD, the time course of these changes and the correlations with motor performance have not been sufficiently investigated. The purpose was to investigate the sequential changes of respiratory, articulatory, and phonatory speech characteristics across a levodopa drug cycle, using spirometry, acoustic, and motor speech analysis. Seven patients with advanced PD were included. All patients were evaluated sequentually at 15 minute intervals before and following levodopa intake. Data were analysed using repeated measures ANOVA and non-parametric analysis. Significant changes were found in motor function, vital capacity, and standard deviation of the diadochokinetic period. A trend was present for shimmer and frequency of the first formant. Significant inter-individual differences in the sequential changes were demonstrated for nearly all evaluated parameters. The conclusion is that, in advanced PD, the evaluation of speech characteristics at one moment after levodopa administration is not representative of an entire drug cycle and that an individualized evaluation of an entire drug cycle is warranted before initiation of a speech-language pathology program.

Long-term multifunctional outcome and risks of face vascularized composite allotransplantation

AbstractVascularized composite allotransplantation (VCA) to reconstruct complex centrally located facial defects and to restore vital functions in a 1-staged procedure has worldwide gained acceptance. Continuous long-term multidisciplinary follow-up of face transplant patients is mandatory for surveillance of the complications associated with the immunosuppressive regime and for functional assessment of the graft.In December 2011, our multidisciplinary team performed a digitally planned face transplant at the Ghent University Hospital, Belgium on a 55-year-old man with a large central facial defect after a high-energy ballistic injury. The patient was closely followed to assess functional recovery, immunosuppressive complications, overall well-being, and quality of life.Three years postoperatively, the patient and his family are very satisfied with the overall outcome, and social reintegration in the community is successful. Motor and sensory functions have recovered near normal. Infectious and medical complications have been serious but successfully managed. Immunosuppressive maintenance therapy consists of corticoids, tacrolimus, and mycophenolate mofetil in minimal doses. Epithetic reconstruction of both eyes gave a tremendous improvement on the overall aesthetic outcome.Despite serious complications during the first 12 months, multifunctional outcome in the first face transplant in Belgium (#19 worldwide) is successful. This should be attributed to the continuous and long-term multidisciplinary team approach. As only few reports of other face transplant patients on long-term follow-up are available, more data need to be collected and reported to further outweigh the risk benefit ratio of this life changing surgery.

Syntactic priming in bilingual patients with parallel and differential aphasia

Background: Syntactic priming is the phenomenon by which the production or processing of a sentence is facilitated when that sentence is preceded by a sentence with a similar syntactic structure. Previous research has shown that this phenomenon also occurs across languages, i.e., hearing a sentence in one language can facilitate the production of a sentence with the same structure in another language. This suggests that syntactic representations are shared across languages. Aims: The aim of the current study is to investigate this cross-lingual syntactic priming in patients with bilingual aphasia. To address this aim, we asked the following three research questions: (1) do patients with bilingual aphasia show priming effects within and across languages? (2) do these priming effects differ from the priming effects observed in control participants? and (3) does the pattern of priming effects interact with the type of aphasia? Methods & Procedures: We tested two groups of patients: one group had similar impairments in both languages (parallel aphasia); in the other group, the impairments were larger in one of the languages (differential aphasia). We investigated syntactic priming within and across languages by means of a dialogue experiment. Outcomes & results: We found significant cross-lingual priming effects in both patient groups as well as in a control group. In addition, the effect size of both patient groups was similar to that of the control group. Conclusions: These findings support models that incorporate shared syntactic representations across languages, and are in favour of a non-localised account of differential aphasia in bilingual aphasia.

Quantitative Analysis of Language Production in Parkinson's Disease Using a Cued Sentence Generation Task.

The present study examined language production skills in Parkinsons disease (PD) patients. A unique cued sentence generation task was created in order to reduce demands on memory and attention. Differences in sentence production abilities according to disease severity and cognitive impairments were assessed. Language samples were obtained from 20 PD patients and 20 healthy control participants matched for age, sex and educational level. In addition, a cognitive test for verbal memory and resistance to cognitive interference was administered. Statistical comparisons revealed significant language changes in an advanced stage of the disease. Advanced PD patients showed a reduction in lexical diversity in notional verbs, which was absent in nouns. Cognitive dysfunctions such as impaired verbal memory are suggested to contribute to the typical noun/verb dissociation in PD patients. In addition, advanced PD patients produced more semantic perseverations, which may be related to set-switching problems. In conclusion, whether language disturbances in PD are the result of non-linguistic cognitive dysfunctions or reflect pure language deficits exacerbated by cognitive impairments, remains a matter of debate. However, the negative impact of cognitive dysfunctions may be important.