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: The traditional approach in neuro-oncology is to study the tumor in great detail and ultimately give little consideration to the brain itself. Choosing the best treatment strategy for each patient with a diffuse low-grade glioma, in other words optimizing the oncologic and functional balance, implies not only a full knowledge of the natural history of this chronic disease, but also an understanding of the adaptation of the brain in response to growth and spread of the glioma. The aim of this review is to examine the mechanisms underlying this neuroplasticity, allowing functional compensation when the tumor progresses, and opening the way to new treatments with the principle of shifting towards "functional personalized neuro-oncology", improving both median survival and quality of life.Diagnostic and interventional imaging. 09/2014;
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ABSTRACT: OBJECT: Recent neuroimaging and surgical results support the crucial role of white matter in mediating motor and higher-level processing within the frontal lobe, while suggesting the limited compensatory capacity after damage to subcortical structures. Consequently, an accurate knowledge of the anatomofunctional organization of the pathways running within this region is mandatory for planning safe and effective surgical approaches to different diseases. The aim of this dissection study was to improve the neurosurgeon's awareness of the subcortical anatomofunctional architecture for a lateral approach to the frontal region, to optimize both resection and postoperative outcome. METHODS: Ten human hemispheres (5 left, 5 right) were dissected according to the Klingler technique. Proceeding lateromedially, the main association and projection tracts as well as the deeper basal structures were identified. The authors describe the anatomy and the relationships among the exposed structures in both a systematic and topographical surgical perspective. Structural results were also correlated to the functional responses obtained during resections of infiltrative frontal tumors guided by direct cortico-subcortical electrostimulation with patients in the awake condition. RESULTS: The eloquent boundaries crucial for a safe frontal lobectomy or an extensive lesionectomy are as follows: 1) the motor cortex; 2) the pyramidal tract and premotor fibers in the posterior and posteromedial part of the surgical field; 3) the inferior frontooccipital fascicle and the superior longitudinal fascicle posterolaterally; and 4) underneath the inferior frontal gyrus, the head of the caudate nucleus, and the tip of the frontal horn of the lateral ventricle in the depth. CONCLUSIONS: Optimization of results following brain surgery, especially within the frontal lobe, requires a perfect knowledge of functional anatomy, not only at the cortical level but also with regard to subcortical white matter connectivity.Journal of Neurosurgery 09/2012; 117(6):1053-69. · 3.23 Impact Factor
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ABSTRACT: Approximately 97% of the right-handers has left hemisphere language dominance. Within the language dominant hemisphere Broca's area is of crucial importance for a variety of linguistic functions. As a result, tumour resection in and around Broca's area is controversial. However, studies showed that by means of Direct Electrical Stimulation (DES) tumour resection in this region can be safely performed. We report unexpected anatomoclinical findings in a right-handed patient who underwent tumour resection in the left prefrontal lobe. Language functions in this right-handed patient were extensively examined in the pre-, intra-, and postoperative phase by means of a standardised battery of neurolinguistic and neurocognitive tests. Results obtained in the pre- and postoperative phase are compared. In addition, intraoperative DES findings and postoperative functional Magnetic Resonance Imaging (fMRI) and Diffusion Tensor Imaging (DTI) results are reported. Tumour resection near Broca's area was safely performed since no positive language sites were found during intraoperative DES. Since no linguistic deficits occurred in the pre-, intra-, or postoperative phase, atypical language dominance was suspected. Neuropsychological investigations, however, disclosed permanent executive dysfunction. Postoperative fMRI and DTI confirmed right cerebral language dominance as well as a crossed cerebro-cerebellar functional link with the left cerebellar hemisphere. Atypical right hemisphere language dominance in this right-handed patient is reflected by: (1) the total absence of language problems in the pre-, intra- and postoperative phase, (2) absence of positive stimulation sites during DES, (3) a clearly more pronounced arcuate fasciculus in the right cerebral hemisphere (DTI), (4) a crossed functional connection between the right cerebrum and the left cerebellum (fMRI). Two hypothetical explanations for the pattern of crossed cerebral language dominance are put forward: (1) preoperative brain plasticity mechanisms inducing a shift of language functions to the right hemisphere or (2) right hemisphere language dominance as a maturational variant. This case with atypical cerebral language dominance shows that although DES is the 'gold standard' to identify eloquent language regions and their pathways, fMRI and DTI are important adjuncts to guide surgery, to identify language lateralisation and to study anatomoclinical correlations.Clinical neurology and neurosurgery 02/2014; 117C:12-21. · 1.30 Impact Factor