Experience with 5-Aminolevulinic Acid in Fluorescence-Guided Resection of a Deep Sylvian Meningioma
A 69-year-old male was admitted to our hospital upon incidental finding of calcification in the left temporal lobe during a computed tomography scan (). Magnetic resonance imaging (MRI) revealed a 2.4×3.0×2.5 cm mass located deeply in the left Sylvian fissure extending into the left temporal lobe. On both T2 and T1-weighted images, it was mainly iso- or hypointense, and enhanced brightly with contrast (). The lesion appeared closely associated with the MCA and was surrounded by moderate edema. Preoperative diagnosis favored an intra-axial tumor, most likely a high-grade oligodendroglioma, which prompted the decision to utilize 5-ALA-induced tumor fluorescence as per standard.\nFour hours before the induction of anesthesia, 20 mg/kg of 5-ALA was administered orally. A left fronto-temporal craniotomy was performed, using intraoperative evoked potential monitoring. In order to ensure no interference, the entire operative field was initially assessed for fluorescence with a Leica M720 OH5 microscope (Leica, Wetzlar, Germany) equipped with FL400 Fluorescence Module. After dissecting the Sylvian fissure, a firm mass was exposed and its red fluorescence under the violet-blue excitation light was confirmed (). It was not well demarcated from the surrounding brain parenchyma. The main mass was grossly removed using a cavitron ultrasonic surgical aspirator under white light illumination. Guided by red fluorescence of the remaining tumor tissue, safe excision was achieved, while small areas of neoplasm with calcified portions were preserved due to their strong adherence to the MCA and the sylvian vein. The fluorescence in tumor was of helpful to delineate tumors from vessels which adjoined under same arachnoid membrane and enabled the safe resection without vessel injury.\nPostoperative MRI () demonstrated the aforementioned unresected MCA-adherent neoplastic areas with calcification. Pathological examination of the fluorescent tumor specimen revealed a benign meningioma (WHO grade I) of psammomatous type (). The patient recovered uneventfully without neurological deficits.