5-Aminolevulinic acid fluorescence guided resection of malignant glioma: Hong Kong experience

5-Aminolevulinic Acid (5-ALA) induced fluorescence is useful in guiding glioma resection. The extent of 5-ALA accumulation is beyond gadolinium contrast enhancement.^1,2 Supratotal resection may be achieved, potentially granting patients with better survival. We present our experience on 5-ALA guided glioma resection in Chinese ethnics.

Sixteen Patients ingested 5-ALA (Gliolan, Medas Germany) 20 mg/kg·m² 4 h before surgery. The tumor resection was guided by fluorescence with neurosurgical microscope. Patient was monitored for general condition, especially for new neurological deficits. Postoperative MRI served as the assessment for extent of resection (EOR).

High grade glioma was confirmed in 12 cases, low grade glioma in three and one inflammation. 5-ALA was used in ten patients with known malignant glioma, and in six patients with presumed diagnosis of malignant glioma. Fifteen cases had positive fluorescence. The intensity was strong in eight and moderate in seven cases. MRI suggested total resection was achieved in 9 patients, near total resection in two and five had subtotal resection. EOR was associated with duration between ingestion of 5-ALA and timing when microscope was brought in for visualization of fluorescence (p = 0.038). Two patients suffered from temporary visual field defects. One patient developed hemiparesis after surgery.

5-ALA is a useful intra-operative guidance for resection. It increases the percentage of total removal of the tumor. It should be used within the window period of the action (4-12 h).