1/4. Intraoperative mapping of the cortical areas involved in multiplication and subtraction: an electrostimulation study in a patient with a left parietal glioma.OBJECTIVES: Advances in neuroimaging studies have recently improved the understanding of the functional anatomy of the calculation processes, having in particular underlined the central role of the angular gyrus (AG). In this study, the authors applied this knowledge to the surgical resection of a glioma invading the left AG, by localising and sparing the cortical areas involved in two different components of calculation (multiplication and subtraction), using direct electrical stimulations. methods: A calculation mapping was performed in a patient without deficit except a slightly impaired performance for serial arithmetic subtraction, during the resection under local anaesthesia of a left parieto-occipital glioma invading the dominant AG. After somatosensory and language mappings, cortical areas involved in single digit multiplications and subtractions of seven were mapped using the method of electrostimulation, before glioma removal. RESULTS: Distinct sites specifically involved in multiplication or subtraction were detected within the left AG, with a precise spatial distribution and overlapping. All the eloquent (somatosensory, language, and calculation) areas were surgically spared. Postoperatively, the patient had a transient complete deficit for arithmetic subtraction, without either multiplication or language disturbance. The tumour removal was complete. CONCLUSIONS: These findings suggest: firstly, the usefulness of an intraoperative calculation mapping during the removal of a lesion involving the left dominant AG, to avoid permanent postoperative deficit of arithmetic processes while optimising the quality of tumour resection; secondly, the possible existence of a well ordered and dynamic anatomo-functional organisation for different components of calculation within the left AG.- - - - - - - - - - ranking = 1keywords = anaesthesia (Clic here for more details about this article) |
2/4. Cortical mapping and resection under local anaesthetic as an aid to surgery of low and intermediate grade gliomas.We report four cases of the use of per-operative cortical mapping during craniotomy under local anaesthesia to define the relationship between the glioma and speech and somatosensory cortex. This enabled a radical subtotal (two cases) or an apparent total (two cases) excision of the tumour close to somatosensory and speech cortex with no permanent neurological deficit. Use of this technique allows radical excision of intrinsic low and intermediate grade gliomas that would otherwise be considered unexcisable and may lead to an improved survival.- - - - - - - - - - ranking = 1keywords = anaesthesia (Clic here for more details about this article) |
3/4. Thalamic glioma. An unusual presentation.Thalamic gliomas, because of their anatomical location, usually present with early and extensive neurologic signs. A case, which at initial presentation had subjective hemianaesthesia, but no objective neurologic deficit, is being reported, to emphasize the importance of proper investigations even in absence of clinical signs.- - - - - - - - - - ranking = 1keywords = anaesthesia (Clic here for more details about this article) |
4/4. Global hemianaesthesia: a parietal perceptual distortion suggesting non-organic illness.In two patients, lesions in the non-dominant parietal lobe were associated with global anaesthesia to all sensory modalities affecting the opposite half of the body. A striking inconsistency existed between the complaints of limb anaesthesia and the grossly preserved motor and postural control of the involved limb. The gross discrepancy between complaint and functional ability prompted early consideration of a "non-organic" diagnosis. It is suggested that this unusual sensory deficit may be due to distorted perception of somatosensory stimuli, representing another disorder of body schema associated with parietal lobe lesions. The diagnosis of non-organic illness may then be avoided by focusing on a search for parietal disease.- - - - - - - - - - ranking = 6keywords = anaesthesia (Clic here for more details about this article) |