Histological considerations of the cleavage plane for preservation of facial and cochlear nerve functions in vestibular schwannoma surgery.
ABSTRACT The authors analyzed the tumor capsule and the tumor-nerve interface in vestibular schwannomas (VSs) to define the ideal cleavage plane for maximal tumor removal with preservation of facial and cochlear nerve functions.
Surgical specimens from 21 unilateral VSs were studied using classical H & E, Masson trichrome, and immunohistochemical staining against myelin basic protein.
The authors observed a continuous thin connective tissue layer enveloping the surfaces of the tumors. Some nerve fibers, which were immunopositive to myelin basic protein and considered to be remnants of vestibular nerve fibers, were also identified widely beneath the connective tissue layer. These findings indicated that the socalled "tumor capsule" in VSs is the residual vestibular nerve tissue itself, consisting of the perineurium and underlying nerve fibers. There was no structure bordering the tumor parenchyma and the vestibular nerve fibers. In specimens of tumors removed en bloc with the cochlear nerves, the authors found that the connective tissue layer, corresponding to the perineurium of the cochlear nerve, clearly bordered the nerve fibers and tumor tissue.
Based on these histological observations, complete tumor resection can be achieved by removal of both tumor parenchyma and tumor capsule when a clear border between the tumor capsule and facial or cochlear nerve fibers can be identified intraoperatively. Conversely, when a severe adhesion between the tumor and facial or cochlear nerve fibers is observed, dissection of the vestibular nerve-tumor interface (the subcapsular or subperineurial dissection) is recommended for preservation of the functions of these cranial nerves.
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ABSTRACT: This review of the literature on vestibular schwannomas focuses on the developments in the fields of surgery, radiosurgery, and observation during the past decade that have redefined the treatment algorithm. The authors hope to derive some recommendations that are evidence based and applicable to everyday clinical practice while advancing the dialogue regarding the optimal management of these lesions. Contemporary review. English literature search for acoustic neuroma or vestibular schwannoma. Radiosurgical treatment appears to maintain strong tumor control during an ever-increasing number of years of follow-up. Fractionated radiation therapy, with attention to limiting the cochlear radiation dose, seems to afford the best hearing-nerve functional outcomes. Microsurgical treatment remains the best cytoreductive therapy, and although it cannot achieve the facial and hearing nerve outcomes of radiosurgery, it is still the preferred treatment for large lesions causing mass effect and obstructive hydrocephalus. Bevacizumab holds substantial promise for the treatment of neurofibromatosis type 2-associated progressive lesions. Our review of the literature suggests that near-total or extensive subtotal resection of vestibular schwannomas may confer much improved functional outcomes without significant detriment to acceptable rates of tumor control. However, further follow-up is needed in patients treated with this relatively novel surgical paradigm.The Laryngoscope 06/2011; 121(6):1133-7. · 1.75 Impact Factor