Three-dimensional views of the target volumes. A – case 1 – large AVM close to the optic chiasm and brainstem. B – case 2 - large AVM involving brainstem and close to the optic pathway. C – case 3 - large AVM encompassing the right optic nerve and close to the brainstem, optic chiasm and right optic tract. D – case 4 - small AVM located inside the brainstem. E – case 5 – small AVM next to the brainstem, F – case 6 – irregular AVM partially located inside the brainstem, G – case 7 – irregular AVM next to the brainstem, H – case 8 – AVM next to the brainstem, I – case 9 – AVM adjacent to the right optic nerve, J – case 10 - AVM involving the brainstem, K – case 11 – large AVM encompassing the left optic nerve and adjacent to the optic chiasm and brainstem, L – case 12 – AVM adjacent to the right optic tract and close to the optic chiasm, M – case 13 – AVM involving the brainstem and adjacent to the optic chiasm, N – case 14 - AVM inside the brainstem and adjacent to the left optic tract, O – case 15 – large AVM adjacent to the brainstem and optic chiasm.