case_images: PMC11380821_01
case_images: Preoperative head magnetic resonance (a: T2-weighted images and b: gadolinium-enhanced T1-weighted images) and computed tomography images (c: left, axial images; right, sagittal images). (a and b) The cystic tumor tumoral lesion is located on the left side of the clivus, showing ring enhancement with gadolinium contrast. The lesion extends into the intracranial space, compressing the brain stem and left internal carotid artery (white arrowhead: internal auditory canal, white arrow: internal carotid artery). (c) The tumor has invaded the left side of the clivus.
case_images: SNI-15-281-g001.jpg
case_images: PMC11380821_01_SNI-15-281-g001.jpg
case_images: F1
case_images: Magnetic resonance imaging revealed a cystic tumor lesion on the left side of the clivus, indicating a residual extracranial hypoglossal schwannoma invading the clivus and compressing the brainstem [Figure 1].
case_images: Intraoperative neuroendoscopic findings. (a) The clivus becomes visible after the nasal pharyngeal membrane is detached caudally. (b) The yellowish tumor lesion is identified lateral to the clivus and dorsal to the longus capitis muscle. (c and d) Views using a neuroendoscope angled at 30 . After subtotal resection of the tumor, the dura of the petrous bone and the inner wall of the internal auditory canal are exposed. The tumor invading the hypoglossal canal (white arrow) is also removed. (C: Clivus; IAC: Internal auditory canal; LoCapM: Longus capitis muscle; NasPhM: Nasal pharyngeal membrane; PetD: Dura of the petrous bone; T: Tumor).
case_images: SNI-15-281-g002.jpg
case_images: PMC11380821_01_SNI-15-281-g002.jpg
case_images: F2
case_images: The mucosa on the anterior wall of the sphenoid sinus and epipharynx was peeled to expose the sphenoid bone and clivus, avoiding arterial injury guided by intraoperative navigation and Doppler ultrasonography [Figure 2a]. The anterior walls of the sphenoid bone and clivus were drilled, and the superior and medial sides of the tumor lesion were confirmed [Figure 2b]. The dura was intact, suggesting that the tumor had grown from the extracranial space [Figure 2c]. A small amount of cerebrospinal fluid (CSF) leaked after removing the tumor from the hypoglossal canal [Figure 2d].
case_images: Postoperative head magnetic resonance (a: T2-weighted images and b: gadolinium-enhanced T1-weighted images) and computed tomography images (c: left, axial images; right, sagittal images). (a and b) Cystic and ring-enhanced tumors are completely removed. Brainstem compression by the tumor is also resolved. (c) The access route from the sphenoid sinus to the clivus is observed.
case_images: SNI-15-281-g003.jpg
case_images: PMC11380821_01_SNI-15-281-g003.jpg
case_images: F3
case_images: Follow-up radiological examination revealed gross total removal of the recurrent schwannoma [Figure 3].