Surgical resection of intrinsic insular tumors: complication avoidance

Object. Surgical resection of tumors located in the insular region is chall enging for neurosurgeons, and few have published their surgical results. Th e authors report their experience with intrinsic tumors of the insula, with an emphasis on an objective determination of the extent of resection and n eurological complications and on an analysis of the anatomical characterist ics that can lead to suboptimal outcomes. Methods. Twenty-two patients who underwent surgical resection of intrinsic insular tumors were retrospectively identified. Eight tumors (36%) were pur ely insular, eight (36%) extended into the temporal pole, and six (27%) ext ended into the frontal operculum. A transsylvian surgical approach, combine d with a frontal opercular resection or temporal lobectomy when necessary, was used in all cases. Five of 13 patients with tumors located in the domin ant hemisphere underwent craniotomies while awake. The extent of tumor rese ction was determined using volumetric analyses. In 10 patients, more than 9 0% of the tumor was resected in six patients, 75 to 90% was resected, and i n six patients, less than 75% was resected. No patient died within 30 days after surgery. During the immediate postoperative period, the neurological conditions of 14 patients (64%) either improved or were unchanged, and in e ight patients (36%) they worsened. Deficits included either motor or speech dysfunction. At the 3-month follow-up examination, only two patients (9%) displayed permanent deficits. Speech and motor dysfunction appeared to resu lt most often from excessive opercular retraction and manipulation of the m iddle cerebral artery (MCA), interruption of the lateral lenticulostriate a rteries (LLAs), interruption of the long perforating vessels of the second segment of the MCA (M-2), or violation of the corona radiata at the superio r aspect of the tumor. Specific methods used to avoid complications include d widely splitting the sylvian fissure and identifying the bases of the per iinsular sulci to define the superior and inferior resection planes, identi fying early the most lateral LLA to define the medial resection plane, diss ecting the MCA before tumor resection, removing the tumor subpially with pr eservation of all large perforating arteries arising from posterior M., bra nches, and performing craniotomy with brain stimulation while the patient w as awake. Conclusions. A good understanding of the surgical anatomy and an awareness of potential pitfalls can help reduce neurological complications and maximi ze surgical resection of insular tumors.