Surgical treatment of glial tumours arising in the insula is specially challenging due to the proximity of the internal capsule. Although small insular gliomas have been removed safely by a transylvian approach, in large dominant insular tumours only biopsy has been recommended to avoid postoperative deficits. Unfortunately that is a suboptimal form of treatment as low grade supratentorial gliomas should be removed radically to prevent tumour progression, malignization and to increase the recurrence-free-interval. Addition of radiotherapy to partial removal is associated with a much higher incidence of recurrences and early malignizations compared to radical removal and no radiotherapy. Between 1st October 1989 and 1st September 1996 we treated twenty-three patients harbouring insular gliomas. To increase the radicality of the resection the surgical procedure was performed under local anaesthesia whenever possible, as general anaesthesia usually leads to more conservative resections. In 20/23 (86.9%) patients complete resection was accomplished, and subtotal in three (13.1%). The removed tumours were: two oligodendrogliomas, five grade I astrocytomas, nine grade II, four grade III and three grade IV. Postoperative neurological deficits occurred in five patients. Four suffered a hemiparesis (that recovered in an average of 6 months) and one a motor dysphasia which took a week to recover. Two of the seventeen patients operated on for low grade insular gliomas underwent malignant change. We conclude that complete surgical removal of insular gliomas should be considered and at least attempted in all cases.

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