gms | German Medical Science

Combination of modern tools seems to be reasonable for more thorough tumor removal and greater safety in surgical treatment of malignant gliomas. Frameless computerized neuronavigation has been increasingly used in intracranial endoscopic neurosurgery. However, a review of literature failed to disclose previous reports dealing with a combination operative therapy concept using fluorescence-guided frameless neuronavigation combined with neuroendoscopy (FGNN). FGNN was developed at our department the last 2 years. The purpose of this study is to evaluate this new surgical combination technique in an attempt to offer a new safe and minimal invasive method. The technique of FGNN will be presented in detail.

During April 2001 and May 2003 we operated 40 patients (22 male, 18 female, mean age 62,5 years) suffering with a malignant glioma using the fluorescence-guided technique with 5-aminolevulinic acid (5-ALA). 5-ALA is a precursor of fluorescent porphyrins that accumulate in malignant gliomas. Based on tumor localisation fluorescence-guided surgery was planed in combination with Neuronavigation and Neuroendoscopy (FGNN) in 28 cases. 12 cases were operated microsurgically. 10 mg 5-ALA/kg body weight was administered orally 4 hours before the induction of anesthesia. Intraoperatively, tumor cavities were illuminated by a xenon short-arc lamp (D-Light, Storz, Tuttlingen, Germany) to deliver blue light (375-440 nm). Connection with a prepared neuroendoscope (Storz, Tuttlingen, Germany) allows resection or biopsies of malignant fluorescent tumor tissue with the help of a frameless neuronavigation system (Vectorvision II, brainlab, Munich, Germany). Data was analysed retrospectively with a mean follow-up period of 16 weeks. Special emphasis is given to the comparison of FGNN and the microsurgical technique.

In our series sensitivity for porphyrin fluorescence was 100% for patients with WHO IV tumors (36 patients). 4 patients with grade III tumors revealed no intraoperative fluorescence. Leasons were located in non eloquent areals (right frontal, right temporal) in 16 patients. In this cases surgery was planned microsurgically and FGNN was only used as a control of radical tumor removal. 24 patients had leasons in eloquent areals with no chance of radical removal because of potential neurological deficits. These patients were operated with FGNN by a minicorticotomy in an attempt of a maximum protection of normal brain tissue. In 20 patients partial resection was possible, in 4 patients only a biopsy could be performed. In one case the operation had to be finished microsurgically because of bleeding complications. Operation time was shorter in FGNN patients (85 min±11 min) than in patients treated microsurgically (120 min±25 min). No patient deteriorated postoperatively.

FGNN offers a save and minimal invasive method for malignant gliomas located in eloquent areals with no chance of total removal. Maximum protection of normal brain tissue is reached because of a minicorticotomy. Nevertheless the microsurgical procedure is the tratment of choice for radical removal in non eloquent areals. With the help of FGNN the neurosurgeon knows where he is, what tissue is malignat, and, what is the most difficult decision, when he has to finish the operation.