Orbit-associated tumors: navigation and control of resection using intraoperative computed tomography

Abstract

S kull base tumors with close anatomical association to orbit, optic nerve, and the cavernous sinus often cause neurological symptoms like loss of visual function and exophthalmus. In most cases resection (complete or partial removal) is the most promising and most effective therapeutic approach with regard to preservation or restoration of visual function. Furthermore, operative tumor removal or reduction is a crucial step in multidisciplinary operative as well as medical or radiotherapeutic treatment concepts, because it allows exact histological diagnosis and safe decompression of anatomical structures at risk. However, resection of these tumors is associated with increased perioperative morbidity due to the proximity of highly sensitive structures-e.g., cranial nerves abbreviatioNs CN = cranial nerve; iCT = intraoperative CT; iMRI = intraoperative MRI; NNS = neuronavigational system. obJective Treatment of skull base lesions is complex and usually requires a multidisciplinary approach. In meningioma, which is the most common tumor entity in this region, resection is considered to be the most important therapeutic step to avoid tumor recurrence. However, resection of skull base lesions with orbital or optic nerve involvement poses a challenge due to their anatomical structure and their proximity to eloquent areas. Therefore the main goal of surgery should be to achieve the maximum extent of resection while preserving neurological function. In the postoperative course, medical and radiotherapeutic strategies may then be successfully used to treat possible tumor residues. Methods to safely improve the extent of resection in skull base lesions therefore are desirable. The current study reports the authors' experience with the use of intraoperative CT (iCT) combined with neuronavigation with regard to feasibility and possible benefits of the method. methods Those patients with tumorous lesions in relationship to the orbit, sphenoid wing, or cavernous sinus who were surgically treated between October 2008 and December 2013 using iCT-based neuronavigation and in whom an intraoperative scan was obtained for control of resection were included. In all cases a second iCT scan was performed under sterile conditions after completion of navigation-guided microsurgical tumor resection. The surgical strategy was adapted accordingly; if necessary, resection was continued. results Twenty-three patients (19 with WHO Grade I meningioma and 4 with other lesions) were included. The most common clinical symptoms were loss of visual acuity and exophthalmus. Intraoperative control of resection by iCT was successfully obtained in all cases. Intraoperative imaging changed the surgical approach in more than half (52.2%) of these patients, either because iCT demonstrated unexpected residual tumor masses or because the second scan revealed additional tumor tissue that was not detected in the first scan due to overlay by osseous tumor parts; in these cases resection was continued. In the remaining cases resection was concluded as planned ...

Use of PET Imaging in Neuro-Oncological Surgery

“…Since their development in the 1990s, SSTR agonists have been increasingly used in meningioma imaging [ 62 ]. The main indication for SSTR PET is identifying meningioma tissue, including the delineation of meningioma extent, especially in complex anatomical regions, such as the skull base or the orbital region, and with a special focus on the diagnosis of intraosseous infiltration [ 63 , 64 ]. For example, 68 Ga-DOTATATE PET was able to identify meningioma out of 13 intraorbital symptomatic lesions with both specificity and sensitivity of 100% [ 65 ].…”

Advances in multidisciplinary therapy for meningiomas

“…Image guidance is used routinely in cranial neurosurgery to position the craniotomy and allows image fusion of multiple datasets that provide information about critical neurovascular structures or transosseous growth. Intraoperative MRI (iMRI) and CT (iCT) can be used to update neuronavigation and identify residual tumor, [26][27][28] particularly for hyperostotic skull base meningiomas. DOTATATE PET can discriminate between meningioma and normal tissues with greater sensitivity than MRI, 29 and may be particularly useful for meningioma with intraosseous involvement.…”

Evaluasi Tajam Penglihatan Dan Indeks Proptosis Pasien Meningioma Sphenoorbita Pascaoperasi Kraniektomi

“…12 Pada studi oleh Terpolilli dkk didapatkan 11 dari 13 pasien yang dioperasi hilang atau berkurang secara bermakna penonjolan matanya dalam 3 bulan pascaoperasi. 13 Semua laporan penelitian diatas menggunakan teknik operasi yang relatif standar di seluruh dunia.…”