PMC4533483_01
Case 1. A 47-year-old female with anaplastic oligodendroglioma. Preoperative axial (A) and coronal (B) T1-weighted with gadolinium, axial T2-weighted (C), and axial diffusion-weighted (D) magnetic resonance images showing an enhanced and highly cellular infiltrative tumor in the left insula and fronto-parietal operculum.
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F1
Three-tesla magnetic resonance (MR) imaging revealed a mass in the left insular cortex extending to the fronto-parietal operculum, appearing as high intensity on T2-weighted imaging and low intensity with heterogeneous enhancement on T1-weighted imaging with gadolinium (Fig. 1A-D).
Case 1. A, B: Intraoperative photographs before (A) and after (B) removal of the tumor. Direct cortical stimulation identified the right facial motor (solid circle) and the right hand sensory (dotted circle) responses. The central sulcus is indicated by black arrows. C: Intraoperative photograph showing the pre-central artery (solid arrow) and its perforating branch (dashed arrow) preserved during tumor removal. A temporary clip was applied to this perforating artery. D: ICG video-angiography confirming the vascular patency after release of the temporary clip. E: Intraoperative photograph showing the origin of the perforating artery (center of cross) localized in the upper portion of insula, confirmed by a neuronavigation system. F: MEP monitoring showing the amplitude of the MEP decreased by more than 50% immediately after temporary clipping, but normalized after release of the clip. ICG: indocyanine green, MEP: motor evoked potential.
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Direct cortical stimulation with 10-mA constant current electrical pulses at 50 Hz was performed over the exposed cortex using a bipolar electrode (5 mm spacing) (Fig. 2A, B). Temporary clipping of this branch (Fig. 2C-E) was followed by immediate and significant decrease in MEP amplitude (Fig. 2F). ICG video-angiography later confirmed patency of the vessels (Fig. 2D).
Case 1. Postoperative axial T1-weighted with gadolinium (A), T2-weighted (B), and diffusion-weighted (C) magnetic resonance images showing subtotal resection of the tumor. A small enhanced remnant tumor (arrow in A) was left in the insular cortex. High intensity lesions were seen around the resection cavity, but not in the corona radiata or the territory of long insular artery (C).
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MR imaging revealed subtotal removal of the tumor (Fig. 3A) and no ischemic lesions in the corona radiata (Fig. 3B, C). A small gadolinium-enhanced remnant was left in the upper insular subcortex (Fig. 3A, arrow), which was not removed to preserve the long insular artery.
PMC4533483_02
Case 2. A 43-year-old man with oligo-astrocytoma. Preoperative axial (A) and coronal (B) T1-weighted with gadolinium, axial T2-weighted (C), and axial diffusion-weighted (D) magnetic resonance images showing a non-enhanced right insular and frontal opercular tumor.
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Three-tesla MR imaging revealed a mass in the right insula and frontal operculum, appearing as high intensity on T2-weighted imaging and non-enhanced low intensity on T1-weighted imaging with gadolinium (Fig. 4A-D).
Case 2. A, B: Intraoperative photographs before (A) and after (B) removal of the tumor. The central sulcus is indicated by black arrows. C: Intraoperative photograph showing the central artery (solid arrow) and its perforating branch (dashed arrow) preserved during tumor removal. A temporary clip was applied to the perforating artery. D: ICG video-angiography confirming the vascular patency after release of the temporary clip. E: Intraoperative photograph showing the perforating artery (center of cross) localized in the bottom of tumor close to the corona radiata, confirmed by a neuronavigation system. F: MEP monitoring showing the amplitude of the MEP not changed during temporary clipping of the perforating artery for 10 minutes. The artery was cut for further removal of tumor. ICG: indocyanine green, MEP: motor evoked potential.
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Tumor removal was guided by a neuronavigation system and three "fence-post" tubes inserted at the anterior, posterior, and superior limits of planned resection (Fig. 5A, B). A perforating artery was found to branch from the central artery at the superior limiting sulcus, which was suspected to be a long insular artery (Fig. 5C-E). Temporary clipping of the branch for more than 10 minutes was followed by no changes in the MEP amplitude (Fig. 5F). ICG video-angiography confirmed patency of the vessels after temporary clipping (Fig. 5D). This perforating artery was not judged to supply the descending motor pathway, so that the artery was cut and further tumor removal was possible (Fig. 5B).
Case 2. A, B: Postoperative axial T1-weighted with gadolinium (A) and T2-weighted (B) magnetic resonance images showing gross total resection of tumor. C, D: Axial (C) and coronal (D) diffusion-weighted images (DWIs) showing ischemic changes in the corona radiata with wedge-shaped extension to the lateral ventricle, which is typical of long insular artery infarction. E: Fiber tracking of the pyramidal tract is overlaid and three-dimensionally presented on the DWIs. The pyramidal tract is spared from the infarction (arrows). Diffusion tensor images acquired with 15 gradient directions were analyzed with MRtrix software (http://www.brain.org.au/software). Image overlay on the DWI was performed with AVIZO software (VSG ; Burlington, Massachusetts, USA).
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MR imaging confirmed subtotal removal of the tumor (Fig. 6A, B). Ischemic changes were found in the corona radiata sparing the descending motor pathway (Fig. 6C-E).