Retrosigmoid Intradural Temporal Bone Drilling for Intrapetrous Chondrosarcoma Extending to Cerebellopontine Angle

Recently the intradural temporal bone drilling has been used in conjunction with the retrosigmoid approach to allow expanded to access to a variety of types of intraosseous invasions.^1,2Video 1 demonstrates the intradural temporal bone drilling via the retrosigmoid approach in the microsurgical removal of an intrapetrous chondrosarcoma extending to the cerebellopontine angle. The patient was a 23-year-old woman presented with progressive hearing disturbance, hemifacial spasm, and tinnitus. Neuroimaging revealed a left intrapetrous tumor extending as far as the cerebellopontine angle, destroying the temporal bone around the internal acoustic meatus and petrous carotid artery. Gross total resection was achieved by retrosigmoid intradural temporal bone drilling with electrically activated dissectors and continuous facial nerve monitoring. Because of pathologic diagnosis of chondrosarcoma and due to her preoperative unserviceable hearing, radical removal of the tumor and invaded osseous structures was performed up to the petrous carotid artery and semicircular canals for complete resection, in order to prevent later recurrence. Although slight facial palsy developed postoperatively, the hemifacial spasm and tinnitus disappeared. Her facial palsy almost disappeared within the 6 months of follow-up, and careful observation over a 2-year period revealed no tumor recurrence, without any additional treatment. Informed consent was obtained from the patient.