Ultrasound for Intraoperative Imaging of Acoustic Neuromas

Intraoperative imaging of acoustic neuroma tumors has been difficult to achieve but has the potential to greatly help the surgeon in evaluating how much disease remains, the location of cysts within the tumor, and the relative location of adjacent brain structures. We report our experience with the use of ultrasonography (US) during craniotomy for acoustic neuroma.

The study was conducted on acoustic neuroma patients at the Montreal Neurological Hospital and Institute, a tertiary care institution affiliated with McGill University. We had the opportunity to use two different US units (ATL System and Toshiba). The USs were obtained whenever possible before the tumor resection and in all cases after the tumor removal. We compared the accuracy of the US images with the pre- and postoperative MRIs to asses the specificity of the images obtained. We compared images obtained with surgeons' impressions of the progression of tumor removal and proximity of adjacent structures. We discuss the limitations of this technique. Intraoperative imaging with ultrasound has a minimal impact on OR time and the flow of the surgery. It has considerable potential but requires practice and experience. It certainly enables estimation of the amount of the removal.