Fluorescein-Guided Resection of Intramedullary Spinal Cord Tumors: Results from a Preliminary, Multicentric, Retrospective Study

Background

Intramedullary spinal cord tumors (IMSCTs) are rare, heterogenous lesions that are usually enhanced on preoperative magnetic resonance imaging (MRI) because of a damaged blood-brain barrier. Sodium fluorescein is a dye that accumulates in areas of the central nervous system with a damaged BBB. Given the pattern of MRI contrast enhancement of the majority of IMSCTs, the use of this fluorescent tracer could improve tumor visualization and quality of resection. In this article, we present the first experience with the application of fluorescein-guided technique for surgical removal of IMSCTs.

Methods

Eleven patients (6 men, 5 women; mean age, 50.1 years), harboring 5 ependymomas, 3 hemangioblastomas, 1 astrocytoma, 1 pilocytic astrocytoma, and 1 glioneuronal tumor forming rosettes were included. Sodium fluorescein (5 mg/kg) was injected immediately after patient intubation. Tumors were removed with microsurgical technique and standard neurophysiological monitoring, under YELLOW 560 filter (Pentero 900) visualization. Surgical reports were reviewed regarding usefulness and grade of fluorescein staining. Postoperative MRI was performed within 72 hours after surgery, and postoperative clinical outcome was registered.

Results

No adverse events were registered. Fluorescent staining was reported in 9 of 11 cases (82%), all of them enhancing on preoperative MRI (100% of ependymomas, 100% of pilocytic astrocytomas, 100% of hemangioblastomas). No fluorescence was reported in 1 astrocytoma and 1 glioneuronal tumor–forming rosette. Intraoperative fluorescence was considered helpful for tumor resection in 9 of 11 cases (82%). Gross total resection was obtained in 8 of 11 cases (72.7%).

Conclusions

Our results suggest that fluorescein-guided surgery is a safe and effective technique that can be used during the surgical resection of IMSCTs presenting with contrast-enhancement on preoperative MRI.

Introduction

Intramedullary spinal cord tumors (IMSCTs) are relatively rare neoplasms comprising a miscellaneous group of tumors affecting the central nervous system (CNS). They represent 2%–4% of all CNS neoplastic lesions and are associated with a low incidence of approximately 1.1 cases per 100.000 persons.1, 2 Among them, ependymomas are the most common overall, and they frequently affect the adults, whereas astrocytomas present a much higher occurrence in the pediatric population.³ IMSCTs include heterogeneous lesions, and they consequently present a variable behavior ranging from highly aggressive to relatively indolent clinical course. Despite this finding, most IMSCTs appear with characteristic contrast enhancement on preoperative magnetic resonance imaging (MRI) because of a damaged blood-brain barrier (BBB).4, 5 Because surgical removal with possible gross total resection (GTR) represents the standard of care in the management of these tumors,⁶ the use of technical tools that can increase tumor visualization during surgical procedures could give a major contribution for patient prognosis.

For example, sodium fluorescein (SF) is a dye with the peculiar characteristic of accumulating in areas of the CNS showing damage to the BBB.⁷ Recently, dedicated filters with a specific wavelength for SF have been integrated into the surgical microscope.⁸ In this way, SF has been proposed as a fluorescent tracer for different kinds of tumors of the CNS, including high-grade gliomas, metastasis, lymphomas, and hemangioblastomas.9, 10, 11, 12 Given the pattern of contrast enhancement uptake on MRI of the majority of IMSCTs, the use of this fluorescent tracer could allow a better intraoperative discrimination of the different tumor subtypes compared with the surrounding normal spinal cord parenchyma. To our knowledge, we present the first experience with the application of a fluorescein-guided technique for surgical removal of IMSCTs.