Left precentral gyrus and Broca's aphasia: a clinicopathologic study

We describe an autopsied case in which a circumscribed lesion involving the left precentral gyrus caused mild but lasting Broca's aphasia. The patient developed nonfluent speech and writing disturbances (consistent with mild Broca's aphasia) following malignant lymphoma of the brain. After subtotal resection of the tumor and whole brain irradiation, his language disturbances continued without remarkable change for 3 years until his death. A neuropathologic study indicated that the lesion responsible for the patient's aphasia was restricted to the lower one-third of the precentral gyrus in the left hemisphere. As for the relationship between the left precentral gyrus and Broca's aphasia and its allied syndrome (ie, aphemia), we concluded that in Broca's aphasia the lower part of the precentral gyrus plays a more important role than previously assumed.     

Broca's area aphasias: aphasia after lesions including the frontal operculum

We report 9 cases of aphasia following lesions in the region of the left frontal operculum. It is not possible to capture their variety of clinical manifestations with the simple labels of "Broca's area aphasia." or "Broca's area aphasia." Analysis of the breakdown of various components of speech and language in these cases suggests that the operculum, lower motor cortex, and subjacent subcortical and periventricular white matter contain critical parts of different language systems. These systems can be independently impaired. There are several common language syndromes that follow damage that includes the left frontal operculum. These syndromes reflect the effects of the direction and extent of the lesion in the various language systems.     

Aphasia induced by gliomas growing in the ventrolateral frontal region: assessment with diffusion MR tractography, functional MR imaging and neuropsychology

IntroductionLesions in the ventrolateral region of the dominant frontal lobe have been historically associated with aphasia. Recent imaging results suggest that frontal language regions extend beyond classically defined Broca’s area to include the ventral precentral gyrus (VPCG) and the arcuate fasciculus (AF). Frontal gliomas offer a unique opportunity to identify structures that are essential for speech production. The aim of this prospective study was to investigate the correlation between language deficits and lesion location in patients with gliomas.MethodsNineteen patients with glioma and 10 healthy subjects were evaluated with diffusion tensor imaging magnetic resonance (MR) tractography, functional MR (verb generation task) and the Aachener Aphasie Test. Patients were divided into two groups according to lesion location with respect to the ventral precentral sulcus: (i) anterior (n = 8) with glioma growing in the inferior frontal gyrus (IFG) and underlying white matter; (ii) posterior (n = 11) with glioma growing in the VPCG and underlying white matter. Virtual dissection of the AF, frontal intralobar tract, uncinate fasciculus (UF) and inferior frontal occipital fasciculus (IFOF) was performed with a deterministic approach.ResultsSeven posterior patients showed aphasia classified as conduction (4), Broca (1), transcortical motor (1) and an isolated deficit of semantic fluency; one anterior patient had transcortical mixed aphasia. All posterior patients had invasion of the VPCG, however only patients with aphasia had also lesion extension to the AF as demonstrated by tractography dissections. All patients with language deficits had high grade glioma. Groups did not differ regarding tumour volume. A functional pars opercularis was identified with functional MR imaging (fMRI) in 17 patients.ConclusionsGliomas growing in the left VPCG are much more likely to cause speech deficits than gliomas infiltrating the IFG, including Broca’s area. Lesion extension to the AF connecting frontal to parietal and temporal regions is an important mechanism for the appearance of aphasia.     

Global aphasia without hemiparesis: language profiles and lesion distribution

OBJECTIVES: Global aphasia without hemiparesis (GAWH) is an uncommon stroke syndrome involving receptive and expressive language impairment, without the hemiparesis typically manifested by patients with global aphasia after large left perisylvian lesions. A few cases of GAWH have been reported with conflicting conclusions regarding pathogenesis, lesion localisation, and recovery. The current study was conducted to attempt to clarify these issues. METHODS: Ten cases of GAWH were prospectively studied with language profiles and lesion analysis; five patients had multiple lesions, four patients had a single lesion, and one had a subarachnoid haemorrhage. Eight patients met criteria for cardioembolic ischaemic stroke. RESULTS: Cluster analysis based on acute language profiles disclosed three subtypes of patients with GAWH; these clusters persisted on follow up language assessment. Each cluster evolved into a different aphasia subtype: persistent GAWH, Wernicke's aphasia, or transcortical motor aphasia (TCM). Composite lesion analysis showed that persistent GAWH was related to lesioning of the left superior temporal gyrus. Patients with acute GAWH who evolved into TCM type aphasia had common lesioning of the left inferior frontal gyrus and adjacent subcortical white matter. Patients with acute GAWH who evolved into Wernicke's type aphasia were characterised by lesioning of the left precentral and postcentral gyri. Recovery of language was poor in all but one patient. CONCLUSIONS: Although patients with acute GAWH are similar on neurological examination, they are heterogeneous with respect to early aphasia profile, language recovery, and lesion profile.     

Language-related brain function during word repetition in post-stroke aphasics

We compared fMRI findings (using SPM99) obtained with repetition task in normal subjects with those of two patients with Broca's and Wernicke's aphasia who received speech therapy and showed complete recovery. Both aphasic patients with left hemisphere damage who showed complete recovery exhibited activation of only the compensatory area in the right hemisphere during the repetition task. Recovery from Broca's aphasia involves reorganization and neuromodulation between the external temporopolar area and the anterior superior temporal area of the superior temporal gyrus, putamen and the inferior frontal gyrus, while that from Wernicke's aphasia involves reorganization and neuromodulation between the superior temporal gyrus of the temporal region, the posterior supramarginal gyrus and inferior parietal lobule of the parietal region.     

Evidence of cortical reorganization of language networks after stroke with subacute Broca's aphasia: a blood oxygenation level dependent-functional magnetic resonance imaging study

Aphasia is an acquired language disorder that is a common consequence of stroke.The pathogenesis of the disease is not fully understood,and as a result,current treatment options are not satisfactory.Here,we used blood oxygenation level-dependent functional magnetic resonance imaging to evaluate the activation of bilateral cortices in patients with Broca's aphasia 1 to 3 months after stroke.Our results showed that language expression was associated with multiple brain regions in which the right hemisphere participated in the generation of language.The activation areas in the left hemisphere of aphasia patients were significantly smaller compared with those in healthy adults.The activation frequency,volumes,and intensity in the regions related to language,such as the left inferior frontal gyrus(Broca's area),the left superior temporal gyrus,and the right inferior frontal gyrus(the mirror region of Broca's area),were lower in patients compared with healthy adults.In contrast,activation in the right superior temporal gyrus,the bilateral superior parietal lobule,and the left inferior temporal gyrus was stronger in patients compared with healthy controls.These results suggest that the right inferior frontal gyrus plays a role in the recovery of language function in the subacute stage of stroke-related aphasia by increasing the engagement of related brain areas.     

Broca's area: rethinking classical concepts from a neuroscience perspective

Just about one and one-half centuries ago, Paul Broca identified the posterior third left frontal convolution of the human brain as a critical area for speech production. Although years of cerebrovascular accident localization studies partially confirmed Broca's claim, recent years have seen a clarification and expansion of the role Broca's area plays in serial processing of language and speech as well as a probable role in nonlinguistic processing. This article will review some of the more recent anatomical and physiological research, including lesion studies, imaging research, and interoperative electrocortical stimulation studies. The article will summarize the research on the role of the human inferior frontal gyrus in lexical, phonologic, and grammatical production, the so-called "mirror mechanism" and other aspects of cognitive processing and motor execution.     

A case of conduction aphasia due to small infarction in the left parietal lobe]

This is a report on the patient with conduction aphAsia due to small infarction in the left parietal lobe. The patient is a right-handed man aged 74, who developed a speech disorder and mild paralysis of the right hand on November 13. 1996. A CT scan showed a small low-density in the supramarginal gyrus of the left parietal lobe. Standard Language Test of aphasia (SLTA) conducted at five days after admission to the hospital showed preserved auditory comprehension and phonemic para-aphasia symptoms with respect to volitional speech, naming, reading aloud and repetition. Frequent self-correction was also observed while repetition was not remarkably impaired. A test at three months after the onset revealed generally fluent speech, while there still remained occasional phonemic para-aphasia and self-correction for the speech disruption. Three years and four months later, most of the aphasic syndromes disappeared, although the patient claimed he still had difficulty in speaking. This case suggests that conduction aphasia can be caused by a lesion, though small, located in arcuate fibers of the cerebrum. The characteristics are phonemic para-aphasia with respect to general speech functions as well as self-correction toward target words. The indicated that lesions in the pathway connecting Broca's area and Wernicke's area causes difficulties in selecting accurate phonemes due to a malfunctioning interface between the two areas.     

Frontal lobe gray matter density decreases in bipolar I disorder.

BACKGROUND: This study was conducted to explore differences in gray and white matter density between bipolar and healthy comparison groups using voxel-based morphometry (VBM). METHODS: Brain magnetic resonance imaging was performed for 39 subjects with bipolar I disorder and 43 comparison subjects. Images were registered into a proportional stereotaxic space and segmented into gray matter, white mater, and cerebrospinal fluid. Statistical parametric mapping was used to calculate differences in gray and white matter density between groups. RESULTS: Bipolar subjects had decreased gray matter density in left anterior cingulate gyrus (Brodmann's area [BA] 32, 7.3% decrease), an adjacent left medial frontal gyrus (BA 10, 6.9% decrease), right inferior frontal gyrus (BA 47, 9.2% decrease), and right precentral gyrus (BA 44, 6.2% decrease), relative to comparison subjects. CONCLUSIONS: The observation of a gray matter density decrease in the left anterior cingulate, which processes emotions, in bipolar subjects is consistent with prior reports that used region-of-interest analytic methods. Decreased gray matter density in the right inferior frontal gyrus, which processes nonverbal and intrinsic functions, supports nondominant hemisphere dysfunction as a component of bipolar disorder.     

A case of crossed aphasia with echolalia after the resection of tumor in the right medial frontal lobe]

We report a right-handed woman, who developed a non-fluent aphasia after resection of astrocytoma (grade III) in the right medial frontal lobe. On admission to the rehabilitation department, neurological examination revealed mild left hemiparesis, hyperreflexia on the left side and grasp reflex on the left hand. Neuropsychologically she showed general inattention, non-fluent aphasia, acalculia, constructional disability, and mild buccofacial apraxia. No other apraxia, unilateral spatial neglect or extinction phenomena were observed. An MRI demonstrated resected areas in the right superior frontal gyrus, subcortical region in the right middle frontal gyrus, anterior part of the cingulate gyrus, a part of supplementary motor area. Surrounding area in the right frontal lobe showed diffuse signal change. She demonstrated non-fluent aprosodic speech with word finding difficulty. No phonemic paraphasia, or anarthria was observed. Auditory comprehension was fair with some difficulty in comprehending complex commands. Naming was good, but verbal fluency tests for a category or phonemic cuing was severely impaired. She could repeat words but not sentences. Reading comprehension was disturbed by semantic paralexia and writing words was poor for both Kana (syllabogram) and Kanji(logogram) characters. A significant feature of her speech was mitigated echolalia. In both free conversation and examination setting, she often repeated phrases spoken to her which she used to start her speech. In addition, she repeated words spoken to others which were totally irrelevant to her conversation. She was aware of her echoing, which always embarrassed her. She described her echolalic tendency as a great nuisance. However, once echoing being forbidden, she could not initiate her speech and made incorrect responses after long delay. Thus, her compulsive echolalia helped to start her speech. Only four patients with crossed aphasia demonstrated echolalia in the literature. They showed severe aphasia with markedly decreased speech and severe comprehension deficit. A patient with a similar lesion in the right medial frontal lobe had aspontaneity in general and language function per se could not be examined properly. Echolalia related to the medial frontal lesion in the language dominant hemisphere was described as a compulsive speech response, because some other 'echoing' phenomena or compulsive behavior were also observed in these patients. On the other hand, some patients with a large lesion in the right hemisphere tended to respond to stimuli directed to other patients, so called 'response-to-next-patient-stimulation'. This behavior was explained by disinhibited shift of attention or perseveration of the set. Both compulsive speech responses and 'response-to-next-patient-stimulation' like phenomena may have contributed to the echolalia phenomena of the present case.     

Speech planning and execution in children who stutter: Preliminary findings from a fNIRS investigation

Few studies have investigated the neural mechanisms underlying speech production in children who stutter (CWS), despite the critical importance of understanding these mechanisms closer to the time of stuttering onset. The relative contributions of speech planning and execution in CWS therefore are also unknown. Using functional near-infrared spectroscopy, the current study investigated neural mechanisms of planning and execution in a small sample of 9–12 year-old CWS and controls (N = 12) by implementing two tasks that manipulated speech planning and execution loads. Planning was associated with atypical activation in bilateral inferior frontal gyrus and right supramarginal gyrus. Execution was associated with atypical activation in bilateral precentral gyrus and inferior frontal gyrus, as well as right supramarginal gyrus and superior temporal gyrus. The CWS exhibited some activation patterns that were similar to the adults who stutter (AWS) as reported in our previous study: atypical planning in frontal areas including left inferior frontal gyrus and atypical execution in fronto-temporo-parietal regions including left precentral gyrus, and right inferior frontal, superior temporal, and supramarginal gyri. However, differences also emerged. Whereas CWS and AWS both appear to exhibit atypical activation in right inferior and supramarginal gyri during execution, only CWS appear to exhibit this same pattern during planning. In addition, the CWS appear to exhibit atypical activation in left inferior frontal and right precentral gyri related to execution, whereas AWS do not. These preliminary results are discussed in the context of possible impairments in sensorimotor integration and inhibitory control for CWS.     

Foreign accent syndrome: Behavioural and anatomical findings in recovered and non-recovered patients

Abstract

Four right-handed monolingual Spanish-speaking patients who developed a foreign accent syndrome (FAS) during the recovery period from a non-fluent aphasia or an aphemia are reported. The FAS resolved rapidly (within 2 months) in two patients, both with small stroke lesions in the posterior margin of the left middle frontal gyrus. In the other two patients, who had lesions involving the middle portion of the left precentral gyrus and the white matter underlying the right sensory-motor cortex, the FAS lasted more than 1 year. Phonetic and fundamental frequency (F0) analysis showed atypical articulatory and prosodic patterns in the two patients with a long-lasting FAS, but only abnormal prosodic features in the two recovered cases. These findings suggest that: (1) a selective involvement of specific portions of Brodmann's areas 4 and 6, and/or its subcortical projections, may account for the peculiar combination of segmental and prosodic deficits underlying the FAS; and (2) recovery seems to be related to small variations in lesion location, since a transient FAS was associated with damage to cortical areas implicated in the modulation of speech prosody (i.e. premotor cortex), while a longer-lasting FAS was associated with damage restricted to areas mainly related to articulation (i.e. precentral gyrus).     

Speech apraxia without oral apraxia: can normal brain function explain the physiopathology?

Apraxia of speech, usually associated with stroke, refers to the inability to perform speech motor movements typically with an intact ability to execute non-speech oral movements. It is uncertain whether apraxia of speech results from damage affecting the insula or the inferior frontal gyrus. The controversy started because of conflicting results from studies investigating patients with disrupted brain structure, when dysfunction of both sites can coexist. We conducted a functional magnetic resonance imaging study of individuals without neurological disorders comparing speech and non-speech movements. Speech movements did not recruit the insula, but activated the left inferior frontal gyrus, suggesting that Broca's area, but not the insula, is critical for speech articulation.     

An autopsy case of transcortical motor aphasia

An autopsy case of transcortical motor aphasia is presented with a pathology located anterior and superior to the pars opercularis of the left inferior frontal gyrus. Case H. Y. A 60-year-old right-handed man. On Nov. 14, 1978, the patient had surgery to remove cerebral hematoma in the left frontal lobe. In the neuropsychological examination before the operation, he had shown the clinical features of transcortical motor aphasia characterized by good comprehension of language, preserved repetition, and spontaneous speech disorder. In this stage, it was supposed that the underlying disturbance of spontaneous speech was due to the disabilities of contextual constructions of sentences rather than the lack of speech initiation. Following the operation, however, spontaneous speech disappeared completely for several days. At the same time, the patient showed problems in comprehension, reading, writing and confrontation naming as well as symptoms of disorientation, pathological inertia and 'loss of initiation' in the psychomotor domain. During the following three months, however, the patient did show slight improvement, except for contextual sentence constructions and pathological inertia when taking the complex animal drawing test. In his terminal stages, the clinical symptoms could be summarized as transcortical motor aphasia and mild frontal lobe syndrome. On March 1, 1979, the patient died of Hamman-Rich syndrome. Postmortem examination: The brain weighed 1294 gm. The external observation of the brain disclosed the linear tissue defect, about 15 mm in length and 10 mm in width, along the radial sulcus of the pars triangularis of the left inferior frontal gyrus.(ABSTRACT TRUNCATED AT 250 WORDS)     

Enhanced response of the left frontal cortex to slowed down speech in dyslexia: an fMRI study

Language difficulties of dyslexic subjects may result partly from a basic deficit in processing rapidly changing sensory inputs. In this fMRI study, we compared brain activities in adult dyslexics and controls during implicit categorical perception of phonemes with normal and slowed down stimuli. Perception of phonemic contrasts activated a frontal parietal network (Broca's area and the left supramarginal gyrus) in which the frontal component was down-regulated by slowed speech in controls and enhanced in dyslexic subjects. No modulation by speech rate was observed in the left supra-marginal gyrus. Enhancement of activity in Broca's area for slowed speech in dyslexic subjects might represent a neural basis of the improvement of performance that has been observed after remediation using this type of stimuli.     

Acoustic and semantic disturbances of comprehension in aphasia]

The authors carried out a verbal auditory comprehension test on 115 aphasic patients, 44 patients suffering from a left hemispheric lesion without aphasia and 120 normal subjects used as acontrol group. The test also revealed either disorders in acoustico-phonemic discrimination or difficulities in semantic differentiation. The main aim of the research was to check experimentally the theory propounded by Alajouanine and colleagues (1964) according to which, in Wernicke's aphasia, it is possible to demonstrate a twofold correlation between disorders of comprehension and speech disorders both phonemic and semantic. Only one part of the theory of Alajouanine and colleagues has been confirmed by our experiments for our results have shown that there is a very close correlation between semantic paraphasias and disorders of semantic differentiation whilst no correlation can be found between phonemic paraphasias and disturbances in auditory phonemic discrimination.     

Anatomic basis of transcortical motor aphasia

Analysis of language profiles and CT anatomy in transcortical motor aphasia (TCMA) suggests that the essential lesion is disruption of connections at sites between the supplementary motor area and the frontal perisylvian speech zone. If the lesion is extended, there may also be poor articulation (lesion deep to motor strip for face), impaired auditory comprehension (lesion in anterior head of caudate, anterior limb internal capsule, anterior putamen, and anterior portion of external capsule, claustrum, extreme capsule, and insula), or stuttering (lesion in pars opercularis and lower third of premotor region). This concept unifies disparate anatomic and psychophysiologic observations about three syndromes: classical TCMA, aphasia after left medial frontal infarction, and TCMA during recovery from Broca's aphasia.