Can excision of meningiomas be limited to resection of tumor and radiologically abnormal dura mater? Neuronavigation-guided biopsies of dural tail and seemingly normal dura mater, with a review of the literature

The etiology of the 'dural tail' around meningiomas remains unclear. The enhancement is either due to tumor invasion or to hypervascularity. We histologically examined both the radiological dural tail, and the radiologically seemingly normal dura around a meningioma using neuronavigation, in order to determine the presence of tumor tissue. On pre-operative MR-scans, normal dura and dural tail biopsy locations were defined. The biopsies of the seemingly normal dura were neuronavigationally targeted within 1 cm of the edge of the tumor. Biopsies were histologically examined. PUBMED and EMBASE were searched to review articles on histologically examined dural tails. Eleven patients were included. Tumor invasion was seen in 55% of the dural tails and in 36% of normal dura. For WHO grade I and II respectively, the dural tail contained tumor cells in 38% and 100%, and the non-enhancing dura was infiltrated in 13% and 100% of the patients. The literature review showed tumor infiltration in 47% of the dural tails. We suggest to continue meningioma excision with a margin of 1 cm radiologically normal dura and also to aim for resection of the complete dural tail, as a high percentage of tumor invasion in the dural tail was found, especially for WHO grade II meningiomas. Perhaps the removal of an additional dural margin around the tumor might further reduce the chance of recurrence. Routine postoperative radiotherapy of WHO grade II meningiomas might be warranted seeing the 100% tumor infiltration of normal, non-enhancing dura. Further research is warranted