Intraoperative fluorescein staining for benign brain tumors.

OBJECTIVE: Successful use of high-dose fluorescein-sodium (20mg/kg) with a standard light microscope for resection of high-grade gliomas, meningiomas, hemangioblastoma and metastases was reported. The principle of brain tumor staining by fluorescein-sodium (Fl-Na) consists in the accumulation of fluorescein in brain tumors with impaired blood-brain barrier. The aim of our study was to investigate for the first time the usefulness of high-dose fluorescein in patients operated on for benign neuroepithelial brain tumors (grade I WHO tumors) with contrast enhancement on magnetic resonance imaging.

METHODS: Our study included 11 patients operated on for benign neuroepithelial primary brain tumors with contrast enhancement on magnetic resonance imaging (MRI): pilocytic astrocytomas (5 patients), dysembrioplastic neuroepithelial tumors (4) and gangliogliomas grade I (2). In all cases, Fl-Na was injected intravenously (20mg/kg) just after the craniotomy using a peripheral venous line. The dural opening was performed 10min later. Microsurgical tumor resection using conventional neurosurgical microscope guided by the fluorescein staining was performed.

RESULTS: Complete resection of the yellow-green stained tissue was achieved in 10 patients confirmed by postoperative control MRI study. Subtotal resection of the colored tissue was achieved in one case with fourth ventricle pilocytic astrocytoma because of the involvement of the medial eminence and functional constraints discovered during intraoperative neuromonitoring. Three patients have had a postoperative volume of resection greater than the tumor volume because of the planed perilesionectomy by our epilepsy surgery team. Surrounding tissue not stained by Fl-Na was obtained in these 3 cases. The histopathological examination did not find tumor tissue in the perilesional Fl-Na negative tissue. On the other hand, all 11 Fl-Na positive specimens presented signs of tumor involvement. We did not observe complications related to the use of high dose Fl-Na.

CONCLUSIONS: High doses intravenous Fl-Na seems to be a useful intraoperative technique for delineation of benign neuroepithelial brain tumors with contrast enhancement. Further larger studies may reveal the real value of high doses Fl-Na as intraoperative method for increasing the extent of resection in these particular indications.