Intraoperative ultrasound and 5-ALA: the two faces of the same medal?

BACKGROUND: High grade gliomas (HGG) still remain the most demanding neuro-oncological challenge. Several studies have confirmed that the extent of resection (EOR) correlates with increased survival in patients with HGGs. The gross total resection of HGGs can be difficult and challenging. For this reason, technologies to improve EORhave been of interest. The aim of this paper was to analyze advantages and limitations of both intraoperative fluorescence and intraoperative ultrasound (IOUS) resection techniques. METHODS: Our work deals with the comparison of one group of 15 patients treated with both tools (study group) with a control group of 15 patients in where only fluorescence was used. Postoperative outcome are valued using Karnofsky Performance Status scale (KPS) while EOR are valued with MRIwithin 24 hours after surgery. RESULTS: The difference between the postoperative KPS and between EOR in the 2 groups resulted not statistically significant considering P<0.05. In our experience 5-ALAhas a limited sensitivity before starting resection while shows its central role in identifying the tumor remnants after its removal. Conversely, IOUSis very useful in identifying the tumor before starting resection. After the tumor removal, the sensitivity of the ultrasound in identifying tumor remnants in the margins of the cavity decreases significantly. However, in one case, at the end of resection, we have not visualized any fluorescent tissue but we detect a residual of tumor using the IOUS. CONCLUSIONS: In our preliminary experience we observed that there are no significant advantages using IOUS+5-ALA. However, we feel that IOUS is useful in the first step of resection and fluorescence in the last steps of operation. Therefore these two technologies could be considered the two faces of the same medal as they can help the surgeon to detect the tumor in every step of tumor resection.