Crossed aphasia elicited by intraoperative cortical and subcortical stimulation in awake patients.
ABSTRACT Crossed aphasia (aphasia resulting from a right hemispheric lesion among right-handed patients) is rare. The authors describe for the first time transient crossed aphasia elicited by intraoperative electrostimulation of both cortex and white matter pathways in awake patients.
Three right-handed adults underwent surgery for a right-sided glioma. Because slight language disorders occurred during partial seizures or were identified on preoperative cognitive assessment, with right activations detected on language functional MR imaging in 1 patient, awake craniotomy was performed using intraoperative cortico-subcortical electrical functional mapping.
Transient language disturbances were elicited by stimulating discrete cortical areas (inferior frontal gyrus and posterior part of the superior temporal gyrus) and white matter pathways (inferior frontooccipital fasciculus and arcuate fasciculus). A subtotal resection was achieved in all cases, according to functional boundaries. Postoperatively, 1 patient experienced a transient dysphasia, which resolved after speech rehabilitation, with no permanent deficit.
These original findings highlight the possibility of finding crucial cortico-subcortical language networks in the right hemisphere in a subgroup of atypical right-handed patients. These findings provide new insights into the neural basis of language, by underlining the role of the right inferior occipitofrontal fasciculus in semantics and that of the right arcuate fasciculus in phonology, and by supporting the hypothesis of a mirror organization between the right and left hemispheres. The authors suggest that, in right-handed patients, if language disturbances are detected during seizures or on presurgical neuropsychological assessment, especially when right activations are observed on language functional MR imaging, awake craniotomy with intraoperative language mapping should be considered.
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ABSTRACT: Cerebral reorganization during recovery after stroke has been investigated using functional imaging in patients with subcortical motor stroke. The functional correlates of recovery from anarthria, however, are yet unknown. A 48-year-old male patient recovering from complete anarthria after unilateral right-sided subcortical hemorrhagic stroke is described. The main outcome measures included clinical and neuroimaging data at three different time points (at the onset of symptoms, after 6 weeks and after 6 months). At 6 weeks, increased activations in the right and left frontal operculum were found and were followed by a trend towards normalization of the activation pattern at 6 months. These results suggest a role of anterior opercular regions in recovery from anarthria after subcortical stroke. Moreover, complete recovery is possible after such lesions.Journal of Neurology 08/2012; · 3.58 Impact Factor
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ABSTRACT: WHO grade II glioma, i.e. diffuse low-grade glioma, is a pre-malignant tumour, usually revealed by seizures in young patients with a normal life. This tumour has a constant growth, and will inescapably become anaplastic. Surgical resection significantly increases the overall survival by delaying the malignant transformation. Thus, the dilemma is to perform early surgery in order to optimise the extent of resection (and thus the median survival) by removing smaller tumours while preserving the quality of life. To this end, the new concept proposed in this review is to achieve surgical resection according to functional and not to oncological boundaries. In other words, the principle is to first understand the cerebral anatomo-functional organisation at the individual level (because of a major inter-individual variability), with the aim of resecting a part of the brain invaded by a diffuse chronic disease, on the condition nonetheless that this part of the brain can be functionally compensated-i.e. with no consequences on the quality of life. To this end, in addition to the preoperative functional neuroimaging and the intraoperative electrical cortical mapping in awake patients, it is also crucial to map both horizontal cortico-cortical connectivity (long-distance association fibres) as well as vertical cortico-subcortical connectivity (projection fibres), with the aim to preserve the networks underlying the minimal common core of the brain. Interestingly, this "hodotopical" workframe, based on the study of both cortical epicentres and subcortical pathways, opens the door to mechanisms of functional reshaping. These recent technical and conceptual advances in the hodotopical and plastic view of brain processing have allowed a dramatic improvement of the benefit-to-risk ratio of surgery, concerning both oncological and functional outcomes. In summary, it is time to move towards "functional neurooncology" and "preventive neurosurgery" in low-grade gliomas. Stronger interactions with fundamental neurosciences should be developed, in order (1) to build updated models of cognition and brain plasticity; (2) to elaborate biomathematical models of low-grade glioma growth and migration; (3) to study in silico the dynamic interactions between the natural course of this disease and the adaptative behaviour of its host (the brain), with the goal to adapt the best individualised therapeutic strategy.Acta Neurochirurgica 01/2012; 154(4):569-74. · 1.55 Impact Factor
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ABSTRACT: Knowledge on the patterns of repetition amongst individuals who develop language deficits in association with right hemisphere lesions (crossed aphasia) is very limited. Available data indicate that repetition in some crossed aphasics experiencing phonological processing deficits is not heavily influenced by lexical-semantic variables (lexicality, imageability, and frequency) as is regularly reported in phonologically-impaired cases with left hemisphere damage. Moreover, in view of the fact that crossed aphasia is rare, information on the role of right cortical areas and white matter tracts underpinning language repetition deficits is scarce. In this study, repetition performance was assessed in two patients with crossed conduction aphasia and striatal/capsular vascular lesions encompassing the right arcuate fasciculus (AF) and inferior frontal-occipital fasciculus (IFOF), the temporal stem and the white matter underneath the supramarginal gyrus. Both patients showed lexicality effects repeating better words than non-words, but manipulation of other lexical-semantic variables exerted less influence on repetition performance. Imageability and frequency effects, production of meaning-based paraphrases during sentence repetition, or better performance on repeating novel sentences than overlearned clichés were hardly ever observed in these two patients. In one patient, diffusion tensor imaging disclosed damage to the right long direct segment of the AF and IFOF with relative sparing of the anterior indirect and posterior segments of the AF, together with fully developed left perisylvian white matter pathways. These findings suggest that striatal/capsular lesions extending into the right AF and IFOF in some individuals with right hemisphere language dominance are associated with atypical repetition patterns which might reflect reduced interactions between phonological and lexical-semantic processes.Frontiers in Human Neuroscience 01/2013; 7:675. · 2.91 Impact Factor