Endoscopic-Assisted Anterior Petrosectomy for a Recurrent Petrous Chondrosarcoma in Ollier Disease: 2-Dimensional Operative Video.

Ollier disease (OD) is characterized by the formation of multiple enchondromas. Patients with OD can develop malignant tumors, most often chondrosarcomas. When chondrosarcomas occur at the skull base in OD, cure is often difficult to obtain by surgery being lesion limits poorly distinguishable within the extensive pathological bone. Owing to the possible multiplicity of lesions over time, radiotherapy, in particular proton therapy, should be used with caution. The goal of surgery is therefore maximal resection with functional preservation followed with a careful follow-up. In this video, the case of a 13-year-old girl with an OD and an incidentally found petrous apex chondrosarcoma is presented. An endoscopic endonasal biopsy was performed confirming the diagnosis of chondrosarcoma. Conservative management was chosen initially. Because of symptoms progression and significant tumor growth, surgical removal was proposed. Considering the limited pneumatization of the sphenoid sinus and the lateral location of the lesion, an endoscopic-assisted anterior petrosal approach was chosen. A small remnant of tumor was left below the internal auditory canal. Because of its progressive growth, an additional resection using the same surgical approach was performed, with additional anterior petrosal drilling along and below the cochlea under endoscopic guidance to remove the part of the lesion located under the internal auditory canal. Ultimately, gross total resection of the lesion was achieved. All human studies have been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. The patient's relatives provided informed consent to the surgical treatment, video recording, and publication of the data. The patient's relatives provided consent to the procedures. This work was performed according to the ethical standards of our Institutional Review Board, without the need for dedicated IRB approval.

Combined Transpetrosal Approach: 2-Dimensional Operative Video.

INDICATIONS CORRIDOR AND LIMITS OF EXPOSURE: This approach is suitable for petroclival lesions medial to V cranial nerve that extend in both middle and posterior fossa. It provides multiple surgical corridors with minimal brain retraction. ANATOMIC ESSENTIALS NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT: Several critical neurovascular structures of the petrous bone are at risk during the approach. Meticulous reading of the preoperative images is fundamental. It is mandatory to perform a thin section computed tomography scan, an MRI, and, in case of petroclival meningiomas, a digital subtraction angiography. ESSENTIAL STEPS OF THE PROCEDURE: In the first illustrative case, we present our current "mini-combined petrosectomy" with minimal drilling of the labyrinth. Positioning, skin incision, and craniotomy are illustrated in the video. Once all the important neurovascular structures are identified, we perform the anterior and the posterior petrosectomy, with preservation of the endolymphatic sac. We continue with dura mater opening and tentorium cutting. After tumor removal, we can appreciate an unique view of ipsilateral and contralateral cranial nerves, as well as pituitary stalk and major arteries. PITFALLS/AVOIDANCE OF COMPLICATIONS: To avoid injuries to the main neurovascular structures, neuronavigation, neuromonitoring, and Doppler can be useful. VARIANTS AND INDICATIONS FOR THEIR USE: The second illustrative case shows an extension of the combined petrosectomy to the anterior fossa, this made possible to perform a transsylvian approach for this giant sphenopetroclival meningioma. The patients consented to the procedure and to the publication of his/her images. Appropriate consent was obtained for the publication of the cadaveric images.

Tailored frontotemporoorbitozygomatic (FTOZ) craniotomy for a large anterior clinoidal meningioma.

Large anterior clinoidal meningiomas are tumors that arise on the anterior clinoid often compressing and encasing the nearby neurovascular structures such as the carotid artery and the optic nerve. These remain as very challenging cases for neurosurgeons because of the issues concerning preservation of critical structures and gross total excision. In this video submission, we will show a case of a large anterior clinoidal meningioma through a tailored frontotemporoorbitozygomotic craniotomy with emphasis on anterior clinoidectomy and the different corridors that can be obtained by this particular approach. The methodical dissection of the tumor and the other critical structures can also be seen.

Endoscope-assisted anterolateral approach for a craniovertebral junction chordoma.

Chordomas of craniovertebral junction represent a challenging pathology for neurosurgeons, due to their deep location, proximity with critical neurovascular structures and local aggressiveness. Several surgical options are available for these tumors: both endoscopic extended approaches and open approaches. We present the case of a 24 years old female with a craniovertebral junction chordoma with anterior and right lateral extension. For this case, an anterolateral approach with endoscopic assistance was chosen. Key surgical steps are presented. In the postoperative course the neurological symptoms improved and there were no complications. Unfortunately, she had an early recurrence of tumor two months later, prior the beginning of radiotherapy. After multidisciplinary consultation, we performed a second surgical removal and a posterior cervical spine arthrodesis. The anterolateral approach is a valuable option for craniovertebral junction chordomas with lateral extension and the endoscope assistance allowed to reach the narrowest and furthermost points. The patients must be referred to multidisciplinary skull base surgery centers and be addressed to early adjuvant radiation therapy.