Clinical Study Space-occupying cyst development in the resection cavity of malignant gliomas following Gliadel Ò implantation – incidence, therapeutic strategies, and outcome Lutz Dörner a,⇑,  , Stephan Ulmer b,  , Axel Rohr b , H. Maximilian Mehdorn a , Arya Nabavi a a Department of Neurosurgery, Universitätsklinikum Schleswig-Holstein Campus, Arnold Heller Strasse 3,24105 Kiel, Germany b Institute of Neuroradiology, Universitätsklinikum Schleswig-Holstein Campus, Arnold Heller Strasse 3,24105 Kiel, Germany article info Article history: Received 22 April 2010 Accepted 12 May 2010 Keywords: BCNU wafer Cyst Gliadel Ò Malignant glioma Mass effect abstract Gliadel Ò (Eisai Inc., Woodcliff Lake, NJ, USA) is the only therapeutic agent approved by the Food and Drug Administration and the European Medicines Agency for local chemotherapy of malignant gliomas. With increasing use of this treatment, characteristic side effects have become evident. While most side effects can be managed conservatively, cyst formation requires further intervention. From 2004 to 2009 at our institution 88 patients with malignant gliomas were treated with Gliadel Ò . Ten patients (11%) developed a space-occupying cyst in the resection cavity, seven of which caused clinical symptoms of mass effect that was most prominent 2 weeks after Gliadel Ò implantation (median = 16, range = 9–30). Despite dexa- methasone treatment symptoms progressed, necessitating various surgical interventions. In four patients the cysts were drained percutaneously through a burrhole using a 19-gauge needle. If puncture was not possible (three patients) or not sufficient (two patients), an Ommaya reservoir was implanted for repet- itive drainage. In two patients this treatment was combined with open decompression of the cyst. On average, cysts were drained three times. Eventually the symptoms subsided, corresponding to shrinkage of the cysts as shown on follow-up imaging. We describe a serious side effect of local chemotherapy, which may cause rapid clinical deterioration and require direct intervention. While reservoir implanta- tion apparently represents a more elegant treatment option, our experience shows that draining the cyst, even only a few times, sufficiently ameliorates the symptoms and subsequently reverses and halts further cyst enlargement. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Local chemotherapy is increasingly being used for the adjuvant treatment of malignant gliomas. Gliadel Ò (Eisai Inc., Woodcliff Lake, NJ, USA), a polifeprosane wafer loaded with 7.7 mg carmus- tine, was approved for use in primary malignant glioma and recur- rent glioblastoma multiforme following the trials by Brem et al. and Westphal et al. 1,2 Gliadel Ò wafers are placed along the wall of the resection cavity after removal of the tumor and carmustine is released continuously, diffusing into the parenchyma, with a peak release in the first 2 weeks. 1,2 A notable side effect of Gliadel Ò is local edema adjacent to the resection cavity that occurs, appar- ently, due to local immunoreactions; it can also develop in convec- tion-enhanced delivery. 2,3 Edema can cause significant mass effect requiring treatment with anti-edema medication and some patients may require hospitalization. 4 The reaction reportedly recedes over time, however, and is not predictive of a negative outcome. 5,6 While various side effects have been identified and thoroughly analyzed, 4 cystic enlargement of the resection cavity resulting in additional mass effect has only been reported for a total of six pa- tients in two publications. 7,8 This complication is thought to be rare; however, its actual incidence is not well characterized. Awareness of this complication and possible therapeutic options are of importance for neurooncologists because these cysts can cause increased intracranial pressure and rapid clinical deterioration. 2. Materials and methods We retrospectively reviewed the charts of 88 patients with malignant gliomas treated by gross tumor resection and local che- motherapy with Gliadel Ò at our institution during a 5-year period (2004 to 2009). All side effects were documented. Patients who developed reactive cysts (Table 1) resulting in a clinically signifi- cant mass effect were analyzed. 0967-5868/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jocn.2010.05.036 ⇑ Corresponding author. Tel.: +49 431 597 4801; fax: +49 431 597 4872. E-mail address: doernerl@nch.uni-kiel.de (L. Dörner).   Authors contributed equally to the manuscript. Journal of Clinical Neuroscience 18 (2011) 347–351 Contents lists available at ScienceDirect Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn