Abstract Date: 5/2/2015
Konstantinos N. Fountas, MD, PhD
Eftychia Kapsalaki, MD, PhD
Ioannis Tsougos, PhD
Patricia Svolos, PhD
Ioannis Siasios, MD
Theophanis Giannis, MD
Konstantinos Vagkopoulos, MD
Anastasia Tasiou, MD, PhD
Haralampos Gatos, MD
Ioanna Kasselouri, PhD
Ioannis Fezoulidis, MD, PhD (Volos, Greece)
Preservation of vision becomes of paramount importance during the resection of tumors located anywhere along the visual pathway. However, the actual location of the visual tract may be highly variable, and the possibility of its displacement is increased when intra-axial brain lesions are present. The purpose of our study was to preoperatively delineate, and intraoperatively identify the visual pathway in patients undergoing tumor resection.
In a prospective study, 18 consecutive patients, with tumors located along or close to the theoretical anatomical position of the post-chiasmatic visual pathway, were included. All patients were evaluated preoperatively with MR imaging including Diffusion Tensor Imaging (DTI) for delineating the visual pathway. They underwent surgery for tumor resection with frameless neuronavigation, intraoperative visual evoked potential recording, and bipolar cortical/subcortical stimulation. Pre- and post-operative visual acuity and visual field examinations were routinely obtained.
Preoperative DTI identified the visual pathway in 13/18 (72.2%) cases. Visual evoked potential recording was feasible in all patients, while intraoperative stimulation confirmed the visual pathway in 12/18 (66.7%) cases. The topographic accuracy of DTI, compared to the stimulation studies, was ≤10 mm in 7/12 (58.3%) cases. Worsening of the preoperative visual examination was observed in 4/18 (22.2%) patients.
Our data support the concept of preoperative identification of the visual pathway by employing DTI. The accuracy of the DTI was approximately 58% in our cohort. However, in a significant number of cases (27.8%), our DTI methodology was not feasible. Further development of the method may well increase its clinical applicability and accuracy.
Article ID: AA-31543