5-Aminolevulinic acid fluorescence-guided endoscopic surgery for deep-seated intraparenchymal tumors

The usefulness of 5-aminolevulinic acid (5-ALA) fluorescence-assisted surgery for maximum resection of malignant gliomas has been established. However, its usefulness when combined with endoscopic surgery for deep-seated tumors has not been well established. In this study, whether 5-ALA photodynamic diagnosis (PDD) is feasible and useful for endoscopic surgery was investigated.

A specially designed endoscope for PDD that delivers white light or blue light (375-440 nm) as excitation light was used. The fluorescence emitted by the tumor was evaluated in the cavity during resection or at the tip of the sheath during biopsy. The intensity of fluorescence was classified into three categories: strong, vague, and negative.

A total of 30 intraparenchymal tumors were observed with a neuroendoscope and 5-ALA PDD; 16 patients underwent resection, and 14 underwent biopsy. Overall, 67% (20/30) of tumors showed positive fluorescence of protoporphyrin IX. High-grade gliomas (HGGs) including glioblastoma (GBM) and anaplastic astrocytoma (AA) showed strong fluorescence in 47% (7/15), vague fluorescence in 33% (5/15), and negative fluorescence in 20% (3/15) of cases. Low-grade gliomas (LGGs) showed vague fluorescence in 33% (1/3) and negative fluorescence in 67% (2/3). Diffuse large B-cell lymphoma (DLBCL) showed vague fluorescence in 38% (3/8) and negative fluorescence in 63% (5/8). Metastatic tumors showed strong fluorescence in 25% (1/4) and vague fluorescence in 75% (3/4). In the comparison of fluorescence evaluation, a significant difference was observed only in the comparison between HGGs and DLBCL (p = 0.049).

These results suggest that 5-ALA PDD-assisted endoscopic surgery is feasible and useful for deep-seated intraparenchymal tumors.