Efficacy of Intraoperative Ultrasound in Resection of Posterior Fossa Lesions

To evaluate the important role of Intraoperative Ultrasound (IOUS) in measurement of pre & postoperative resection volume of an intra-axial posterior fossa lesions and to compare these results with that measured in pre and post-operative MRI brain. Also, to assess the principal surgeon opinion regarding the ability of IOUS in localization and differentiating the borders of those lesions, and his comfortability during handling of this device. There are different methods, which are helpful to localize precisely and allow maximum tumor resection, such as neuro-navigation, intraoperative MRI, 5-aminolevulinic acid, as well as IOUS. Every method has its pros & cons. Although Intraoperative MRI Provides real time updated images, however it’s not available in most of neurosurgery centers in developing countries. So, with these financial and ergonomic limitations of the Intraoperative MRI, usage of Intraoperative Ultrasound could be considered as a potential competitor in developing world. This is a prospective study conducted at Ain Shams University hospital in the period from February 2016 to July 2018, we enrolled 23 patients presented with posterior fossa intra axial neoplasms that operated with Intra Operative Ultrasound (IOUS) assistance. IOUS was able to well localize the lesions in 96% of cases and it was able to differentiate solid and cystic parts in all the cases. IOUS was able to define well the lesion borders in 20/23 (87%) of cases. There was no difference between volumes calculated from preoperative MRI and the pre-resection IOUS, also there was no significant difference between the residual volume detected by the IOUS and the postoperative MRI brain. Principal surgeon reported overall great impression of the IOUS in 18/23 (78%) of cases. Mean total additional time of usage of the IOUS was 27min. IOUS was found to be valuable in localization of the lesions, differentiating solid and cystic parts and detection of the residual volume in the posterior fossa intra axial tumors.