Excellent recovery of aphasia in a patient with complete injury of the arcuate fasciculus in the dominant hemisphere

The arcuate fasciculus (AF) is the neural tract that connects Wernicke's area and Broca's area. The main role of the AF is speech repetition; therefore, injury to the AF typically causes conduction aphasia. We report on a patient who showed excellent recovery of aphasia despite complete injury of the AF due to a cerebral infarct. A 54-year-old, right-handed male presented with aphasia and right hemiparesis. Brain MRI showed an infarct in the left centrum semiovale and corona radiata. Diffusion tensor tractography for the AF was reconstructed using DTI-studio software. The Korean-Western Aphasia Battery (K-WAB) was used for measurement of language function. On K-WAB at 1 week after onset, his aphasia type was compatible with global aphasia (aphasia quotient: 12‰, fluency: 5‰, comprehension: 24‰, repetition: 15‰, and naming: 31‰). The patient underwent rehabilitative therapy, including language therapy and medication, which is known to facilitate recovery from aphasia, for a period of 24 months. His aphasia had improved to a nearly normal state at 30 months after onset; aphasia quotient: 93‰ (fluency: 91‰, comprehension: 92‰, repetition: 85‰, and naming: 96‰). The left AF showed a complete disruption on 27-month diffusion tensor tractography. Findings from this study suggest the possibility that aphasia might show good recovery, even in cases of severe injury of the AF.     

Study on the pathogenic mechanism of Broca's and Wernicke's aphasia

OBJECTIVE: To study the mechanisms of aphasia by observing cerebral blood flow and metabolism changes in language functional areas of the brain using imaging, in order to develop a language rehabilitation plan for aphasia patients. METHODS: Fifty-eight patients who suffered from Broca's or Wernicke's aphasia secondly to cerebral infarction were evaluated using the Western aphasia battery and Frenchay dysarthria assessment. CT and MRI were obtained to identify the location of lesions, and the language areas were analysed with magnetic resonance spectroscopy (MRS) and perfusion-weighted imaging (PWI). The results were compared with those of the contralateral hemisphere. RESULTS: Of the 58 patients, there were 23 Broca's aphasia patients, 29 Wernicke's aphasia patients and six other aphasia types. We excluded five patients accompanied by dysarthria, six patients with other aphasia types and 14 patients with much more disease lesions. Finally, we analysed the remaining 12 Broca's aphasia and 21 Wernicke's aphasia patients by MRS and PWI. MRS shows that the N-acetylaspartate, choline and creatine of the Broca's or Wernicke's area were reduced than those of the contralateral hemisphere, while PWI results show that the damaged Broca's or Wernicke's areas were in a hypoperfusion state. CONCLUSIONS: Broca's or Wernicke's area of aphasia patients exhibits hypoperfusion and hypometabolism, indicating that they might be the mechanisms of Broca's or Wernicke's aphasia.     

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.     

Neuroanatomic correlation of the post-stroke aphasias studied with imaging

BACKGROUND AND PURPOSE: Stroke is the leading cause of disability in many countries. Aphasia is a common sign of stroke that is observed in about one-third of stroke patients and contributes to disease morbidity. However, the relationship between anatomy and different forms of aphasia remains poorly understood. We intend to study the characteristics of aphasia in the acute stage of stroke and to identify neuroanatomical correlates using MRI. METHODS: Lesion sites were selected from 1198 patients with cerebral infarction, who were hospitalized in the stroke unit of our hospital between March 2002 and March 2006. We enrolled 325 patients who fulfilled our criteria. All patients received an MRI examination within 1 week after admission and were evaluated with the Western battery aphasia (WAB) test, in order to determine what type of aphasia they had. The severity of their language deficit was further classified using the Boston diagnostic aphasia examination (BDAE) severity grading standard. RESULTS: Among 1198 cases, five cases with Broca's areas and four cases with Wernicke's areas lesions on MRI works were free of language deficits. Within the 325 patients who demonstrated clinical signs of aphasia, the results of WAB showed that there were 83 Broca' aphasia cases, 48 Wernicke's aphasia cases, 12 conduction aphasia cases, 36 transcortical motor aphasia cases, 17 transcortical sensory aphasia cases, 19 transcortical mixed aphasia cases, 58 global aphasia cases and 52 anomic aphasia cases. Two hundred and eighty-eight cases were located within classical language centers while 37 cases were located at other sites. In 325 aphasia patients with grade criteria of BDAE of grades 0, 1, 2, 3 or 4, there were 84, 79, 77, 63 and 22 cases respectively. Many of cases with grades 0 and 1 were distributed within classical language centers. CONCLUSION: This study showed that it is possible to draw a neuroanatomical map of aphasia that encompasses the 95% of aphasia cases. It also demonstrates that the main determinant of aphasic disorders is the neuroanatomical location of the lesion. Furthermore, this study shows that most lesion locations associated with specific aphasic disorders fit classical data associated with previous aphasia research. More importantly, the language disorders of patients whose lesions were located at classical language centers were more serious. Consequently, this paper demonstrates the power of MRI in prognosticating the potential for a patient to recover from aphasia due to stroke.     

Plasticity of language-related brain function during recovery from stroke

BACKGROUND AND PURPOSE: This study was undertaken to correlate functional recovery from aphasia after acute stroke with the temporal evolution of the anatomic, physiological, and functional changes as measured by MRI. METHODS: Blood oxygenation level-dependent contrast and echo-planar MRI were used to map language comprehension in 6 normal adults and in 2 adult patients during recovery from acute stroke presenting with aphasia. Perfusion, diffusion, sodium, and conventional anatomic MRI were used to follow physiological and structural changes. RESULTS: The normal activation pattern for language comprehension showed activation predominately in left-sided Wernicke's and Broca's areas, with laterality ratios of 0.8 and 0.3, respectively. Recovery of the patient confirmed as having a completed stroke affecting Broca's area occurred rapidly with a shift of activation to the homologous region in the right hemisphere within 3 days, with continued rightward lateralization over 6 months. In the second patient, in whom mapping was performed fortuitously before stroke, recovery of a Wernicke's aphasia showed a similar increasing rightward shift in activation recruitment over 9 months after the event. CONCLUSIONS: Recovery of aphasia in adults can occur rapidly and is concomitant with an activation pattern that changes from left to a homologous right hemispheric pattern. Such recovery occurs even when the stroke evolves to completion. Such plasticity must be considered when evaluating stroke interventions based on behavioral and neurological measurements.     

Unexpected CT-scan findings in global aphasia

The clinical-CT scan correlation was studied in 37 stroke patients with global aphasia. The time between stroke and language examination was between 21 and 60 days; the time between stroke and CT scan was equal to or longer than 21 days. It was found that while 22 patients harboured the expected large lesions including Broca's and Wernicke's areas, 8 had anterior lesions sparing Wernicke's area, 3 had posterior lesions sparing Broca's area, and 4 had deep lesions centered on the insula and lenticular nucleus. These findings suggest that global aphasia, albeit apparently simple from the semeiological viewpoint (also due to its severity), does in fact include different clinical entities. However, no clear-cut correlation was found between either subtype of speech production or severity, and locus of the lesion (except that deep lesions were associated with somewhat milder forms). An interesting finding, i.e. that all 8 patients with anterior lesions were females, while the 3 posterior ones were male, is briefly discussed in terms of possible differential organization of language functions in the two sexes.     

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.     

Lesion localization in Broca's aphasia. Implications from Broca's aphasia without hemiparesis

The recent hypothesis that injury of the left precentral gyrus (PCG) is critical in causing Broca's aphasia implies that right hemiparesis is an inevitable accompaniment of Broca's aphasia and not merely a coincidental neighborhood sign of PCG damage. A right-handed man was evaluated for posttraumatic Broca's aphasia. The absence in this case of limb or central facial weakness strongly suggests that language impairments of Broca's aphasia need not be associated with PCG damage.     

Japanese crossed Wernicke's aphasia.

A right-handed Japanese man with no personal or family history of left-handedness developed severe Wernicke's aphasia, a mild constructional disorder, and slight left hemiparesis. MRI revealed infarction in the territory of the righ middle cerebral artery, including areas homologous to Broca's and Wernicke's areas. The cerebral blood flow in these areas remained diminished even after language activation. The most likely explanation is that language production occurred in the left Broca's area, while language comprehension occurred in the right Wernicke's area (a dissociated aphasia).     

Double dissociation of Hangul and Hanja reading in Korean patients with stroke

The orthographic system of the Korean language consists of both phonogram (Hangul) and ideogram (Hanja). We report 2 patients who revealed selective impairment in reading either of orthographies after the brain damages. YJ, a 67-year-old man, showed Broca's aphasia and severe apraxia of speech after a stroke in the left inferior parietal lobe. He demonstrated predominant difficulties in reading phonogram. KS, a 51-year-old woman, had an intracerebral hemorrhage in the left parietal lobe. She showed anomic aphasia and a selective impairment on reading ideogram. These findings support the notion that recognition of visual words is processed in different ways depending on the characteristics of orthographic systems.     

Aphasia after stroke: type, severity and prognosis. The Copenhagen aphasia study

AIM: To determine the types, severity and evolution of aphasia in unselected, acute stroke patients and evaluate potential predictors for language outcome 1 year after stroke. METHODS: 270 acute stroke patients with aphasia (203 with first-ever strokes) were included consecutively and prospectively from three hospitals in Copenhagen, Denmark, and assessed with the Western Aphasia Battery. The assessment was repeated 1 year after stroke. RESULTS: The frequencies of the different types of aphasia in acute first-ever stroke were: global 32%, Broca's 12%, isolation 2%, transcortical motor 2%, Wernicke's 16%, transcortical sensory 7%, conduction 5% and anomic 25%. These figures are not substantially different from what has been found in previous studies of more or less selected populations. The type of aphasia always changed to a less severe form during the first year. Nonfluent aphasia could evolve into fluent aphasia (e.g., global to Wernicke's and Broca's to anomic), whereas a fluent aphasia never evolved into a nonfluent aphasia. One year after stroke, the following frequencies were found: global 7%, Broca's 13%, isolation 0%, transcortical motor 1%, Wernicke's 5%, transcortical sensory 0%, conduction 6% and anomic 29%. The distribution of aphasia types in acute and chronic aphasia is, thus, quite different. The outcome for language function was predicted by initial severity of the aphasia and by the initial stroke severity (assessed by the Scandinavian Stroke Scale), but not by age, sex or type of aphasia. Thus, a scoring of general stroke severity helps to improve the accuracy of the prognosis for the language function. One year after stroke, fluent aphasics were older than nonfluent aphasics, whereas such a difference was not found in the acute phase.     

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.     

Quantitative Comparison of Language Deficits Produced by Extraoperative Electrical Stimulation of Broca's, Wernicke's, and Basal Temporal Language Areas

Summary: Subdural electrodes were implanted over the language-dominant left lateral convexity in 45 patients undergoing evaluation for epilepsy surgery. In 29 patients, additional electrodes were placed over the left basal temporal cortex. We identified language areas by using intermittent electrical stimuli applied while patients read aloud. Aphasia was classified as expressive or receptive based on additional testing performed when electrical stimulation elicited reading arrest in the absence of direct excitatory or inhibitory motor effects. Using correlated logistic regression, we noted no statistically significant differences among Broca's, and Wernicke's areas and the basal temporal language area (BTLA) regarding the frequency with which electrical stimulation interfered with language. Speech production deficits, however, occurred significantly more frequently in Broca's than in Wernicke's area (p = 0.012). In contrast, language comprehension deficits occurred with equal frequency when Broca's and Wernicke's areas were stimulated. These results suggest that both Broca's and Wernicke's areas play important roles in language comprehension and that the primarily expressive aphasia of patients with lesions of Broca's area results mainly from the predominant participation of Broca's area in language production.     

Global aphasia due to left thalamic hemorrhage

Global aphasia is an acquired language disorder characterized by severe impairments in all modalities of language. The specific sites of injury commonly include Wernike's and Broca's areas and result from large strokes--particularly those involving the internal carotid or middle cerebral arteries. Rarely, deep subcortical lesions may cause global aphasia. We present three cases with global aphasia due to a more rare cause: left thalamic hemorrhage. Their common feature was the large size of the hemorrhage and its extension to the third ventricule. HMPAO-SPECT in one of the cases revealed ipsilateral subcortical, frontotemporal cortical and right frontal cortical hypoperfusion. Left thalamic hemorrhage should be considered in the differential diagnosis of global aphasia.     

Impaired syntactic comprehension and production in Broca's aphasia: CT lesion localization and recovery patterns

Three of 50 patients with left hemisphere stroke manifested Broca's aphasia associated with deficits in syntactic processing. CT demonstrated anterior infarcts in two patients and a posterior infarct in the third. Two years later, all three patients showed improved syntactic production, but only the patient with the posterior lesion performed significantly above change on a sentence comprehension test requiring syntactic manipulations in the absence of semantic constraints. Prospective investigations combining psycholinguistic analyses and brain imaging techniques may provide empiric data relevant to neurologic models of language and ultimately may contribute to patient prognostication and rehabilitation.     

Localisation of lesions in aphasia: clinical-CT scan correlations in stroke patients.

Ninety right-handed patients with present or past evidence of aphasia following a stroke were given a standard language battery and a CT scan examination. Presence and type of aphasia were correlated with the location and extent of the CT scan lesion. Most of the findings were compatible with the traditional views about the localisation of lesions in aphasia (e.g., anterior lesions in nonfluent aphasias with good comprehension, posterior lesions in fluent aphasia, etc.). The possible explanations for some unexpected findings (e.g., purely anterior lesions in global aphasia, or purely deep lesions in Broca's aphasia) are discussed. It is stressed that in establishing clinico-CT scan correlation, careful consideration must be given to the fact that both aphasia and the underlying lesion evolve with time.     

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.     

Cortical language activation in stroke patients recovering from aphasia with functional MRI.

BACKGROUND AND PURPOSE: Two mechanisms for recovery from aphasia, repair of damaged language networks and activation of compensatory areas, have been proposed. In this study, we investigated whether both mechanisms or one instead of the other take place in the brain of recovered aphasic patients. METHODS: Using blood oxygenation level-dependent functional MRI (fMRI), we studied cortical language networks during lexical-semantic processing tasks in 7 right-handed aphasic patients at least 5 months after the onset of left-hemisphere stroke and had regained substantial language functions since then. RESULTS: We found that in the recovered aphasic patient group, functional language activity significantly increased in the right hemisphere and nonsignificantly decreased in the left hemisphere compared with that in the normal group. Bilateral language networks resulted from partial restitution of damaged functions in the left hemisphere and activation of compensated (or recruited) areas in the right hemisphere. Failure to restore any language function in the left hemisphere led to predominantly right hemispheric networks in some individuals. However, better language recovery, at least for lexical-semantic processing, was observed in individuals who had bilateral rather than right hemisphere-predominant networks. CONCLUSIONS: The results indicate that the restoration of left-hemisphere language networks is associated with better recovery and inversely related to activity in the compensated or recruited areas of the right hemisphere.     

Focal brain lesions and intelligence: a study with a new version of Raven's Colored Matrices

Contrasting results have been obtained in previous investigations, which have used the standard version of Raven's Colored Progressive Matrices for studying the effects of localized brain lesion on visual-spatial intelligence. Some of these discrepancies might be due to the fact that specific factors, such as unilateral spatial neglect, could contribute to decreased performance obtained on Raven's test by patients with focal brain lesions. A new set of Colored Matrices, devised to minimize the influence of unilateral spatial neglect without changing the essential features of the original task, was therefore constructed. The test was administered to 76 normal controls, 74 right brain-damaged patients, 87 aphasics, and 61 nonaphasic left brain-damaged patients, in order to study the effect of laterality of lesions and of language impairment on Raven's scores. The results show that, if the influence of unilateral spatial neglect is minimized and Raven's scores are corrected in reference to age, educational level, and lesion size, then: no significant differences are observed between right and left brain-damaged patients; aphasics score worse than nonaphasic left brain-damaged patients; impairment is greater in patients with Wernicke's and Global aphasia (i.e., in patients with severe language comprehension disorders) than in patients classified as Broca's, Anomic, or Conduction aphasia; impairment is greater in patients with semantic-lexical discrimination errors than in patients free from semantic-lexical comprehension disorders.