Use of Ultrasound for Navigating the Internal Carotid Artery in Revision Endoscopic Endonasal Skull Base Surgery

Objective To report the novel use of ultrasound imaging of the cavernous internal carotid artery (ICA) in the setting of revision surgery for clival chordoma. To review the literature concerning the use of ultrasound imaging in endonasal endoscopic skull base surgery.

Methods Case report and review of the literature

Case Report A 56-year-old woman presented to an outside neurosurgeon with complaint of left eye visual loss while visiting her daughter. Imaging revealed a lesion in the clivus extending into the sella, and she underwent a sublabial transsphenoidal approach for subtotal resection of the tumor, with pathology diagnosing clival chordoma. She subsequently presented to our institution, where she was taken for an expanded, endoscopic endonasal approach for resection of remaining chordoma within the left clivus along the petroclival synchondrosis and into the inferior cavernous sinus. The skull base defect was reconstructed with an abdominal fat graft and nasoseptal flap. She received CyberKnife radiosurgery for residual disease, remaining symptom free for 2 years postoperatively. Repeat imaging demonstrated tumor recurrence, this time within the right clivus posterior to the ICA. Revision endoscopic endonasal resection of the recurrent disease was performed. Intraoperatively, it was found that the normal bony architecture of the sella was absent, with the inability to distinguish the anterior genu of the ICA from the adjacent tumor. Using a ProSound Alpha 7 premier ultrasound with endonasal Doppler probe, the course of the ICA was able to be visualized in real time, allowing for safe, gross total resection of the tumor posterior to the ICA (see Fig. 1).

Conclusion In the setting of prior operation, radiation, or extensive disease, the normal bony architecture of the sella may be disrupted, placing the cavernous ICA at risk. Feasibility of ultrasound use during the endoscopic endonasal approach has previously been demonstrated. We report what we believe is the first use of intraoperative ultrasound to intraoperatively map the ICA during the endoscopic endonasal approach in the setting of a previously operated, radiated sella.

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