Altered speech-related cortical network in frontotemporal dementia

BackgroundIn healthy subjects (HS), transcranial magnetic stimulation (TMS) demonstrated an increase in motor-evoked potential (MEP) amplitudes during specific linguistic tasks. This finding indicates functional connections between speech-related cortical areas and the dominant primary motor cortex (M1).ObjectiveTo investigate M1 function with TMS and the speech-related cortical network with neuroimaging measures in frontotemporal dementia (FTD), including the non-fluent variant of primary progressive aphasia (nfv-PPA) and the behavioral variant of FTD (bv-FTD).MethodsM1 excitability changes during specific linguistc tasks were examined using TMS in 24 patients (15 with nfv-PPA and 9 with bv-FTD) and in 18 age-matched HS. In the same patients neuroimaging was used to assess changes in specific white matter (WM) bundles and grey matter (GM) regions involved in language processing, with diffusion tensor imaging (DTI) and voxel-based morphometry (VBM).ResultsDuring the linguistic task, M1 excitability increased in HS, whereas in FTD patients it did not. M1 excitability changes were comparable in nfv-PPA and bv-FTD. DTI revealed decreased fractional anisotropy in the superior and inferior longitudinal and uncinate fasciculi. Moreover, VBM disclosed GM volume loss in the left frontal operculum though not in the parietal operculum or precentral gyrus. Furthermore, WM and GM changes were comparable in nfv-PPA and bv-FTD. There was no correlation between neurophysiological and neuroimaging changes in FTD. Atrophy in the left frontal operculum correlated with linguistic dysfunction, assessed by semantic and phonemic fluency tests.ConclusionWe provide converging neurophysiological and neuroimaging evidence of abnormal speech-related cortical network activation in FTD.     

A case of unilateral opercular syndrome associated with a subcortical lesion

Summary A patient who developed a unilateral opercular syndrome following a cerebrovascular accident is described. Computed tomography showed that the lesion did not affect the opercular cortex, but involved deep white matter and the head of the caudate nucleus of the left hemisphere. Persistent hypophonia and transient aphasia were associated. Comparison with previous cases is discussed.     

Semantic category and initial letter word fluency in left-brain-damaged patients

Fluency deficits have been found in different neuropsychological populations, and dissociation of letter initial and category fluency has been demonstrated in right-brain-damaged and Alzheimer patients. Studies on normal controls also indicate that letter initial and category fluency are supported by different brain regions. We studied letter initial and category fluency in 79 left-brain-damaged patients, 18 non-aphasic and 61 aphasic. Our results indicate that brain-damaged patients are significantly impaired in both fluency tasks compared to normal controls, and a difference between letter initial and category fluency emerges from our data. Firstly, only letter initial fluency is more impaired in aphasic than in non-aphasic patients; secondly, many aphasics have normal category fluency and pathological letter initial fluency but the reverse is seldom true and thirdly, only category fluency scores correlate with confrontation-naming scores. It is suggested that strategies to recover words based on a semantic or a phonological prompt are different. A semantic strategy is coherent with the organizational structure of the semantic system and corresponds to the normal way in which we recover words whereas a phonological strategy is quite unusual and it is not used for actual communication.     

Evaluation of stroke rehabilitation by randomized controlled studies: a review

In all, 22 reports of 20 randomized, controlled rehabilitation studies were evaluated. In 18 of these, the design of the trial was parallel, with a cross-over format being employed in the remaining 2 instances. Seven studies related to intensive rehabilitation during the early post-acute period. In six others, specific techniques--sometimes associated with traditional physiotherapy procedures--were compared: biofeedback, perceptual retraining, and amphetamine treatment. Eight experiments evaluated speech therapy in aphasia. Frequently, methodological considerations limited the interpretation of the results. The review showed that: 1) as regards activities of daily life and motor function, differences as between rehabilitation in stroke units on the one hand and non-rehabilitation or rehabilitation in medical wards on the other, were detected in relatively few quality studies and remained particularly inconclusive insofar as life in the home environment was concerned; 2) rehabilitation for aphasia and perceptual dysfunction proved effective for at least several months after acute stroke; 3) in general, examination of the reports cited revealed no differences in the effects of biofeedback and perceptual retraining vs conventional physiotherapy; 4) rehabilitation, whether administered by specialists or amateur caregivers purpose-trained by specialists, proved equally effective for aphasia. These conclusions constitute a valuable basis for the development and evaluation of modern rehabilitation programs for stroke patients.     

汉语失语症计算机辅助流利性检测的研究

目的研究基于计算机模糊智能识别运算的语言障碍诊治仪ZM2．1（简称：语言障碍ZM2．1）对失语流利性检测的效度与信度。方法采用ABC法和语言障碍ZM2．1两种方法分别对58例失语症患者进行流利性检测，两种方法检测间隔时间在3d之内。结果ABC法流利性内部一致性检验，整体克朗巴赫α系数（Cronbach α）=0．8732；语言障碍ZM2．1平均语速和ABC法流利性总分有正相关性趋势，Spearman系数为0．721（P〈0．01）；语言障碍ZM2．1检测流利性的准确度为81％（以XABC法为标准）；测得两者流利性结果一致性良好（P〈0．01）。结论语言障碍ZM2．1在评价失语症流利性方面具有良好的信度和效度，可用于临床进行失语症的流利性检测。     

TIA磁共振弥散加权成像异常的相关因素分析

目的探讨短暂性脑缺血发作(TIA)磁共振弥散加权成像(DWI)异常的相关因素。方法对2006年1月～2006年12月临床诊断为TIA的住院患者45例进行回顾性分析,比较DWI异常组和正常组的临床特征,并采用Logistic回归分析判定与DWI异常有关的独立因素。结果DWI异常14例(31%);多元回归分析提示TIA症状持续时间≥1h(OR=2.5,95%CI:1.3～8.6)和症状表现为失语伴运动障碍(OR=8.9,95%CI:2.1～36.5)与DWI异常独立相关。结论TIA患者DWI异常与TIA症状持续时间和症状表现为失语伴运动障碍有关。     

Slow event-related brain activity of aphasic patients and controls in word comprehension and rhyming tasks

Slow event-related potentials (ERP) were examined in healthy and aphasic subjects in two-stimulus designs comprising a word comprehension and a rhyming task. Aphasics, though selected to perform above chance level, made significantly more errors and responded more slowly than controls, although canonical correlations did not indicate a statistical relationship between performance measures and ERP amplitudes. A discriminant analysis of ERP amplitudes distinguished the groups for the slow wave (SW; 0.5-1.0 s post-S1 onset) in the word comprehension, for the SW and the initial contingent negative variation (iCNV; 1.0-2.0 s post-S1 onset) in the rhyming task. Similarly for both tasks, ERP topography showed left-anterior predominance of the negative SW and iCNV in controls, whereas participants with aphasia showed smaller anterior and larger left-posterior amplitudes. The centroparietal terminal CNV (tCNV; 1 s pre-S2) was smaller in participants with aphasia than in controls, but similar in topography. Results suggest left-anterior activation for those language processes that were presumably provoked in the present tasks, like lexical access, or phonological encoding. The pattern of participants with aphasia may indicate effects of language impairment and recovery, but also consequences of the brain damage.     

Syntactic and semantic processing in the healthy and aphasic human brain

A syntactic and a semantic task were performed by German-speaking healthy subjects and aphasics with lesions in the dominant left hemisphere. In both tasks, pictures of objects were presented that had to be classified by pressing buttons. The classification was into grammatical gender in the syntactic task (masculine or feminine gender?) and into semantic category in the semantic task (man- or nature made?). Behavioral data revealed a significant Group by Task interaction, with aphasics showing most pronounced problems with syntax. Brain event-related potentials 300-600 ms following picture onset showed different task-dependent laterality patterns in the two groups. In controls, the syntax task induced a left-lateralized negative ERP, whereas the semantic task produced more symmetric responses over the hemispheres. The opposite was the case in the patients, where, paradoxically, stronger laterality of physiological brain responses emerged in the semantic task than in the syntactic task. We interpret these data based on neuro-psycholinguistic models of word processing and current theories about the roles of the hemispheres in language recovery.     

Crossed aphasia. An update

The aim of this article is to present an update of a rare but interesting problem: crossed aphasia. This term indicates the presence of aphasia after unilateral cerebral lesion of the hemisphere ipsilateral to the patient's dominant hand. We report two cases, review the most relevant literature, and analyze clinical, neuroanatomical, and neurophysiological aspects, taking in consideration the various interpretations proposed to explain this unusual language disorder.