5-ALA-Induced Fluorescence in Skull Base Meningiomas: Illustrative Case

Objective: In skull base meningiomas radical tumor resection without additional neurological deficit is the goal of treatment. Incomplete resection increases the local recurrence rate. Any facility to visualize tumor remnants during resection may lower recurrence. We present a case illustration about the application of 5-aminolevulinic acid (5-ALA) in an orbital skull base meningioma.

Methods: A retrospective analysis of the patient data and intraoperative imaging (photo and video documentation) was performed. By application of a modified neurosurgical microscope, the tumor fluorescence status (strong, vague, or negative) and fluorescence homogeneity (homogeneous or heterogeneous) was analyzed. After assumed tumor removal the resection area was checked for fluorescence.

Results: A 51-year-old woman presented with a lateral orbital meningioma without focal neurological deficit. This tumor was found incidentally, magnetic resonance imaging (MRI) was performed due to chronic conjunctivitis and mild proptosis. After presentation of the patient at the Gamma Knife unit, resection of the tumor was the treatment of choice. A standard pterional approach was performed and the tumor was resected. Intraoperatively the tumor showed strong fluorescence pattern. After assumed complete resection under white light, small 5-ALA positive spots could be detected in the depth of the resection area and were subsequently resected. Histopathological analysis of these spots demonstrated to be also meningioma. The postoperative course was uneventful, the follow-up period of 3,5 years showed no recurrence.

Conclusion: The application of 5-aminolevulinic acid (5-ALA) demonstrated visible fluorescence in meningiomas remnants on the skull base, not seen under standard white light.