5-aminolevulinic acid-guided surgery for focal pediatric brainstem gliomas: A preliminary study

Abstract

Background: There is a growing body of literature supporting the use of 5-aminolevulinic acid (5-ALA) in the pediatric population, however, its use is still considered "off label" in this setting. In this retrospective study, we report our experience using 5-ALA in pediatric patients with focal brainstem gliomas (BSGs).

Methods: Patients younger than 16 years presenting with a newly diagnosed BSG that was focal in nature were considered suitable for treatment with 5-ALA-assisted surgery. Exclusion criteria included MRI features suggestive of a diffuse intrinsic pontine glioma. A single dose of 5-ALA was administered preoperatively. Intraoperative fluorescence was recorded as "solid," "vague," or "none." The effectiveness of the fluorescence was graded as "helpful" or "unhelpful."

Results: Eight patients underwent 5-ALA-assisted surgery. There were four tumors located in the pons, two midbrain tumors, and two cervicomedullary tumors. Histological analysis demonstrated three diffuse astrocytomas, three pilocytic astrocytomas, and two anaplastic astrocytomas. Solid fluorescence was found in three of the eight cases, vague fluorescence was found in two cases, and no fluorescence was found in three cases. Fluorescence was useful in 3 (37%) cases. No patients experienced any complications attributable to the administration of the 5-ALA.

Conclusion: With a total fluorescence rate of 62.5% but a subjectively assessed "usefulness" rate of only 37.5%, the role of 5-ALA in BSG surgery is limited. Given the toxicological safety, however, of the agent, caution is perhaps needed before dismissing the use of 5-ALA entirely.

Keywords: 5-aminolevulinic acid; Diffuse intrinsic pontine glioma; Focal brainstem tumors; Pediatric brain tumor.

Figure 1:

Exophytic pontine pilocytic astrocytoma. Top left: preoperative, postgadolinium-enhanced sagittal MRI. Top right: postoperative gadolinium-enhanced MRI revealing subtotal resection. Bottom left: intraoperative white light microscopic view. Arrow: obvious tumor under white light microscopy. Arrowhead: normal appearing tissue under white light microscopy. Bottom right: arrow heads: blue light mode reveals solid fluorescence of both obvious tumor and normal appearing area under white light mode.

Figure 2:

Cervicomedullary pilocytic astrocytoma. Top left: preoperative, postgadolinium-enhanced sagittal MRI. Top right: postoperative gadolinium-enhanced MRI revealing GTR. Bottom left: intraoperative white light microscopic view. Arrow: obvious tumor under white light microscopy. Arrowhead: normal appearing tissue under white light microscopy. Bottom right: arrow heads: blue light mode reveals vague fluorescence of both obvious tumor and normal appearing area under white light mode.