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.

Transdural Thoracic Disk Herniation with Longitudinal Slitlike Dural Defect Causing Intracranial Hypotension: Report of 2 Cases.

BACKGROUND: Intracranial hypotension (IH) has a widely variable clinical and radiologic presentation. Secondary IH may be caused by degenerative spine disorders and in particular by thoracic disk herniations (TDHs). METHODS: We present 2 patients with a transdural TDH, a secondary IH, and superficial siderosis in 1. RESULTS: Case 1 presented with headache, cognitive decline, staggering gait, bilateral subdural effusions, cerebral sagging, an extradural spinal cerebrospinal fluid (CSF) collection suggesting secondary IH, and a calcified TDH at T9-T10. Case 2 presented with intermittent pain at the craniocervical junction provoked exclusively by specific physical activities, superficial siderosis mainly in the posterior fossa, an extradural spinal CSF collection, and a calcified TDH at T7-T8 yet no intracranial signs of IH. In both cases, using strict thoracoscopic technique, we removed a transdural TDH and reconstructed an underlying longitudinal slitlike dural defect with smooth lining. Follow-up magnetic resonance imaging scans confirmed a dramatically improved situation without residual extradural intraspinal CSF collection or signs of IH. CONCLUSIONS: This paper adds to the evidence that some cases of IH and even superficial siderosis are caused by transdural erosion of a TDH that may be otherwise asymptomatic. The dura may degenerate due to chronic compression, and a longitudinal slitlike dural defect with smooth lining may develop, causing continuous (Case 1) or intermittent (Case 2) intraspinal CSF leakage. To the best of our knowledge, such dural defects closely resembling the ones observed in idiopathic spinal cord herniation have never been demonstrated on intraoperative endoscopic video in IH patients.