Dural Involvement in Skull Base Tumors: Accuracy of Preoperative Radiological Evaluation and Intraoperative Evaluation

Introduction: Dural involvement is an important consideration in assessment of cranial-base tumors dictating resectability and prognosis. Preoperative as well as intraoperative clues are valuable but not always correct We evaluated a consecutive series of craniofacial resections at our center to correlate radiologically suspected dural involvement vis a vis intraoperative assessment and eventual pathology.

Materials and Methods: We conducted a retrospective analysis of cases of skull base tumors where potential dural involvement was considered. We recorded the preoperative radiological impression (contrast-enhanced MRI) regarding dural involvement (normal, extradural, intradural, parenchymal disease), intraoperative impression (normal, adherent, subdural, parenchymal disease), and final histology (normal, reactive, tumor). We also recorded instances where the dura was resected and/or inadvertently breached and the incidences of postoperative CSF leak and meningitis.

Results: We evaluated 127 cases. Transcranial approaches were performed in 68 cases and 19% (24 cases) underwent endoscopic procedures. Dural resection was performed in 38 cases (30 of which were proven pathologically). The incidence of CSF leak was 4.7%. The sensitivity, specificity, positive predictive value, and negative predictive value of MR assessment was 34.5%, 97.9%, 83.3%, and 83.2%, respectively, providing an overall accuracy of 84%; and that for intraoperative dural adherence was 84.6%, 85.6%, 44%, 97.6%, and 85.5.%, respectively.

Conclusion: Preoperative MRI, although a good modality for imaging the disease extent, may not always identify the extent of dural involvement. Intraoperative assessment therefore becomes very important, especially when it is unequivocally normal. Both should be used to ensure accurate treatment strategies and to tailor the need for dural resection.