Ultrasonic bone curettage for optic canal unroofing and anterior clinoidectomy. Technical note

Extradural unroofing of the optic canal and subsequent mobilization of the optic nerve is a useful technique in the surgical treatment of parasellar tumors; however, the drilling procedure itself is associated with the risk of optic nerve damage. A safer technique would certainly be beneficial. The ultrasonic bone curette is a device developed in Japan for safer bone removal. Its use in intradural anterior clinoidectomy and opening of the internal auditory meatus has been reported before. In this article the authors describe their experience in using this device for extradural unroofing of the optic canal in patients with parasellar tumors. Between March 2002 and November 2004, the aforementioned technique was used in the treatment of eight patients with parasellar tumors. After undertaking a frontotemporal craniotomy and orbital osteotomy, an ultrasonic bone curette was used to unroof the optic canal via an epidural approach; in five cases anterior clinoidectomy was added subsequently. Using an ultrasonic bone curette, unroofing of the optic canal was completed safely and required much less expertise than that required for standard drilling. The mortality and major morbidity rates were 0%. The visual function outcome was satisfactory, with the overall visual status improving in all seven patients in whom this symptom was present preoperatively. The ultrasonic bone curette makes the unroofing of the optic canal safer and easier, possibly improving the visual outcome of patients undergoing surgery for parasellar tumors.