Neurosurg Focus
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Because multiple anatomical compartments are involved, the surgical management of trigeminal schwannomas requires a spectrum of cranial base approaches. The endoscopic endonasal approach to Meckel's cave provides a minimal access corridor for surgery, but few reports have assessed outcomes of the procedure or provided guidelines for case selection. ⋯ Endoscopic endonasal approaches appear to be well suited for trigeminal schwannomas restricted to Meckel's cave and/or extracranial segments of the nerve. Lateral transcranial skull base approaches should be considered for patients with posterior fossa disease. Further multiinstitutional studies will be necessary for adequate power to help determine relative indications between endoscopic and transcranial skull base approaches.
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Case Reports
Endoscopic endonasal surgical management of chondrosarcomas with cerebellopontine angle extension.
Skull base chondrosarcomas are slow-growing, locally invasive tumors that arise from the petroclival synchondrosis. These characteristics allow them to erode the clivus and petrous bone and slowly compress the contents of the posterior fossa progressively until the patient becomes symptomatic, typically from cranial neuropathies. Given the site of their genesis, surrounded by the petrous apex and the clival recess, these tumors can project to the middle fossa, cervical area, and posteriorly, toward the cerebellopontine angle (CPA). Expanded endoscopic endonasal approaches are versatile techniques that grant access to the petroclival synchondrosis, the core of these lesions. The ability to access multiple compartments, remove infiltrated bone, and achieve tumor resection without the need for neural retraction makes these techniques particularly appealing in the management of these complex lesions. ⋯ Expanded endoscopic endonasal approaches appear to be safe and effective in the resection of select skull base chondrosarcomas; those with predominant CPA involvement seem particularly amenable to resection through this technique. Further studies with larger cohorts are necessary to test these preliminary impressions and to compare their effectiveness with the results obtained with open approaches.
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Case Reports
An endoscopic assisted retrosigmoid approach to the cerebello-pontine angle for resection of an epidermoid cyst.
Epidermoid cysts are rare lesions accounting for 1% of intracranial tumors with approximately 50% located within the cerebello-pontine angle (CPA). Resection is complicated by their close anatomical relation to critical neurovascular structures and their tendency to be densely adherent making complete removal a significant neurosurgical challenge. ⋯ A 30-degree endoscope was used to assist in removal of unseen tumor in Meckel's cave, medial to the lower cranial nerves, and along the ventral pons. The video can be found here: http://youtu.be/bv0lMPbX7BY .
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The posterior skull base and the nasopharynx have historically represented technically difficult regions to approach surgically given their central anatomical locations. Through continued improvements in endoscopic instrumentation and technology, the expanded endonasal approach (EEA) has introduced a new array of surgical options in the management of pathology involving these anatomically complex areas. Similarly, the transoral robotic surgical (TORS) approach was introduced as a minimally invasive surgical option to approach tongue base, nasopharyngeal, parapharyngeal, and laryngeal lesions. ⋯ Given these limitations, several institutions have published feasibility studies with the combined EEA and TORS approaches for a variety of skull base and nasopharyngeal pathologies. In this article, the authors present their clinical experience with the combined endonasal and transoral approach through a case series presentation, and discuss advantages and limitations of this approach for surgical management of the middle and posterior skull base and nasopharynx. In addition, a presentation is included of a unique, simultaneous endonasal and transoral dissection of the nasopharynx through an innovative intraoperative setup.
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Petroclival meningiomas remain a formidable challenge for neurosurgeons because of their location deep within the skull base and proximity to eloquent neurovascular structures. Various skull base approaches have been used in their treatment, and deciding which is the optimal one remains controversial. Attempts at achieving gross- or near-total resections are associated with an increased rate of morbidity and mortality. As adjunctive treatment options such as stereotactic radiosurgery have been developed and become widely available, there has been a trend toward accepting subtotal resections in an effort to minimize neurological morbidity. This paper reviews a recent series of patients with petroclival meningiomas and highlights current management trends and important considerations useful in surgical decision making. ⋯ Achieving gross- or near-total resections of large petroclival meningiomas remains achievable and should be the primary goal of surgical treatment. A retrosigmoid craniotomy remains a workhorse surgical approach for most petroclival tumors of any size. Tumors that are medial to the internal auditory canal and span both middle and posterior cranial fossae are often best treated with a combined transpetrosal approach, which is especially true if there is a preoperative hearing deficit.