The Unrecognized Rotation of the Vestibular and Cochlear Nerves from the Labyrinth to the Brain Stem: Its Implications to Surgery of the Eighth Cranial Nerve

1986 ◽  
Vol 95 (5) ◽  
pp. 543-549 ◽  
Author(s):  
Herbert Silverstein ◽  
Horace Norrell ◽  
Thomas Haberkamp ◽  
Alan B. Mcdaniel
Keyword(s):  
Brain Stem ◽  
Cleavage Plane ◽  
Internal Auditory Canal ◽  
Vestibular Nerve ◽  
Cochlear Nerve ◽  
Eighth Cranial Nerve ◽  
Vestibular Neurectomy ◽  
Intimate Association ◽  
Inferior Vestibular Nerve ◽  
The Brain

The cochlear and vestibular nerves rotate 90 degrees from the inner ear to the brain stem. Most of the rotation occurs within the internal auditory canal (IAC); only minimal rotation occurs in the cerebellopontine (CP) angle. At the labyrinthine end of the IAC, the cochlear nerve—which at first lies anterior to the inferior vestibular nerve (saccular nerve)—rapidly fuses with the inferior vestibular nerve. It then rotates to become inferior as the nerves leave the porus acousticus. The cochleovestibular (C-V) cleavage plane lies in a superior-inferior direction in the lateral IAC and rotates to become anterior-posterior in the CP angle. In 25% of patients in whom no C-V cleavage plane can be seen, it is not possible to completely transect all vestibular fibers. The surgical implications are that (1) the most complete vestibular neurectomy can be done only in the lateral IAC, (2) the cochlear and inferior vestibular nerves, because of their intimate association, should not be separated in the mid-IAC, in order to prevent damage to the cochlear nerve, and (3) to create a complete denervation of the vestibular labyrinth, only the posterior ampullary nerve along with the superior vestibular nerve should be transected.

Suboccipital Surgical Approach to the Cerebellopontine Angle and Internal Auditory Canal

1978 ◽  
Vol 71 (4) ◽  
pp. 273-274 ◽  
Author(s):  
Mansfield F W Smith
Keyword(s):  
Facial Nerve ◽  
Brain Stem ◽  
Prone Position ◽  
Surgical Approach ◽  
Cerebellopontine Angle ◽  
Internal Auditory Canal ◽  
Total Removal ◽  
Size And Shape ◽  
Suboccipital Craniectomy ◽  
The Brain

The suboccipital craniectomy done with the patient in the prone position using modern microsurgical methods gives good anatomical exposure essential for efficient, accurate, total removal of cerebellopontine angle neoplasms and allows adjacent. uninvolved neurological structures to be spared. Modifying the anatomical exposure by varying the size and shape of the osseous craniectomy and placing the dural incision closer to the porus acousticus permits extradural retraction of the cerebellum. Thus large cerebellopontine angle neoplasms can be excised with less chance of damage to the cerebellum and smaller risk of hydrocephalus. The suboccipital craniectomy may be extended anteriorly to the facial nerve, thereby combining the suboccipital with the translabyrinthine approach. and providing a more direct angle to a large neoplasm involving the brain stem and cerebellum.

Histological considerations of the cleavage plane for preservation of facial and cochlear nerve functions in vestibular schwannoma surgery

2009 ◽  
Vol 110 (4) ◽  
pp. 648-655 ◽  
Author(s):  
Tomio Sasaki ◽  
Tadahisa Shono ◽  
Kimiaki Hashiguchi ◽  
Fumiaki Yoshida ◽  
Satoshi O. Suzuki
Keyword(s):  
Connective Tissue ◽  
Basic Protein ◽  
Cleavage Plane ◽  
Nerve Fibers ◽  
Vestibular Nerve ◽  
Cochlear Nerve ◽  
Tissue Layer ◽  
Connective Tissue Layer ◽  
Tumor Capsule ◽  
Tumor Parenchyma

Object 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. Methods Surgical specimens from 21 unilateral VSs were studied using classical H & E, Masson trichrome, and immunohistochemical staining against myelin basic protein. Results 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. Conclusions 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.

Unilateral cochleo-vestibular nerve and internal auditory canal malformations

2018 ◽  
Vol 7 (1) ◽  
pp. 59-64
Author(s):  
Henryk Kaźmierczak ◽  
Wojciech Kaźmierczak ◽  
Katarzyna Pawlak-Osińska ◽  
Stanisław Osiński
Keyword(s):  
Case Report ◽  
Developmental Disorders ◽  
Internal Auditory Canal ◽  
Vestibular Nerve ◽  
Cochlear Nerve ◽  
Diagnostic Process

A case report of unusual one-sided developmental disorders of the vestibular and cochlear nerve and the internal auditory canal and difficulty of diagnostic process.

Tumor origin and hearing preservation in vestibular schwannoma surgery

2011 ◽  
Vol 115 (5) ◽  
pp. 900-905 ◽  
Author(s):  
Jens Rachinger ◽  
Stefan Rampp ◽  
Julian Prell ◽  
Christian Scheller ◽  
Alex Alfieri ◽  
...  
Keyword(s):  
Vestibular Schwannoma ◽  
Tumor Size ◽  
Hearing Preservation ◽  
Vestibular Nerve ◽  
Cochlear Nerve ◽  
Nerve Function ◽  
Nerve Preservation ◽  
Tumor Origin ◽  
Inferior Vestibular Nerve ◽  
Vs Removal

Object Preservation of cochlear nerve function in vestibular schwannoma (VS) removal is usually dependent on tumor size and preoperative hearing status. Tumor origin as an independent factor has not been systematically investigated. Methods A series of 90 patients with VSs, who underwent surgery via a suboccipitolateral route, was evaluated with respect to cochlear nerve function, tumor size, radiological findings, and intraoperatively confirmed tumor origin. All patients were reevaluated 12 months after surgery. Results Despite comparable preoperative cochlear nerve status and larger tumor sizes, hearing preservation was achieved in 42% of patients with tumor originating from the superior vestibular nerve, compared with 16% of those with tumor originating from the inferior vestibular nerve. Conclusions Tumor origin is an important prognostic factor for cochlear nerve preservation in VS surgery.

Preservation of tap vestibular evoked myogenic potentials despite resection of the inferior vestibular nerve

2004 ◽  
Vol 14 (4) ◽  
pp. 347-351 ◽  
Author(s):  
Krister Brantberg ◽  
Tiit Mathiesen
Keyword(s):  
Bone Conduction ◽  
Vestibular Function ◽  
Vestibular Nerve ◽  
Vestibular Evoked Myogenic Potentials ◽  
Nerve Function ◽  
Sound Stimulation ◽  
Vestibular Loss ◽  
Vestibular Neurectomy ◽  
Inferior Vestibular Nerve ◽  
Healthy Side

Sound and skull-tap induced vestibular evoked myogenic potentials (VEMP) were studied in a 43-year-old man following inferior vestibular neurectomy. Surgery was performed because of a small acoustic neuroma. Postoperative caloric testing suggested sparing of superior vestibular nerve function on the operated side. In response to sound stimulation there were no VEMP on the operated side, irrespective of whether sounds were presented by air- or bone-conduction. This suggests sound-induced VEMP to be critically dependent on inferior vestibular nerve function and this is in agreement with present knowledge. However, VEMP were obtained in response to forehead skull taps, i.e. positive-negative VEMP not only on the healthy side but also on the operated side. This suggests remnant vestibular function on the operated side of importance for forehead skull tap VEMP, because with complete unilateral vestibular loss there are no (positive-negative) VEMP on the lesioned side. Thus, forehead skull-tap VEMP depend, at least partly, on the superior vestibular nerve function.

scholarly journals Endoscope-assisted middle fossa craniotomy for resection of inferior vestibular nerve schwannoma extending lateral to transverse crest

2018 ◽  
Vol 44 (3) ◽  
pp. E7 ◽  
Author(s):  
Adam N. Master ◽  
Daniel S. Roberts ◽  
Eric P. Wilkinson ◽  
William H. Slattery ◽  
Gregory P. Lekovic
Keyword(s):  
Facial Nerve ◽  
Internal Auditory Canal ◽  
Senior Author ◽  
Vestibular Nerve ◽  
Gross Total Resection ◽  
Preoperative Imaging ◽  
Speech Discrimination ◽  
Middle Fossa ◽  
Total Resection ◽  
Inferior Vestibular Nerve

OBJECTIVEThe authors describe their results using an endoscope as an adjunct to microsurgical resection of inferior vestibular schwannomas (VSs) with extension into the fundus of the internal auditory canal below the transverse crest.METHODSAll patients who had undergone middle fossa craniotomy for VSs performed by the senior author between September 2014 and August 2016 were prospectively enrolled in accordance with IRB policies, and the charts of patients undergoing surgery for inferior vestibular nerve tumors, as determined either on preoperative imaging or as intraoperative findings, were retrospectively reviewed. Age prior to surgery, side of surgery, tumor size, preoperative and postoperative pure-tone average, and speech discrimination scores were recorded. The presence of early and late facial paralysis, nerve of tumor origin, and extent of resection were also recorded.RESULTSSix patients (all women; age range 40–65 years, mean age 57 years) met these criteria during the study period. Five of the 6 patients underwent gross-total resection; 1 patient underwent a near-total resection because of a small amount of tumor that adhered to the facial nerve. Gross-total resection was facilitated using the operative endoscope in 2 patients (33%) who were found to have additional tumor visible only through the endoscope. All patients had a House-Brackmann facial nerve grade of II or better in the immediate postoperative period. Serviceable hearing (American Academy of Otolaryngology–Head and Neck Surgery class A or B) was preserved in 3 of the 6 patients.CONCLUSIONSEndoscope-assisted middle fossa craniotomy for resection of inferior vestibular nerve schwannomas with extension beyond the transverse crest is safe, and hearing preservation is feasible.

Nerve origin of vestibular schwannoma: a prospective study

2007 ◽  
Vol 122 (2) ◽  
pp. 128-131 ◽  
Author(s):  
T Khrais ◽  
G Romano ◽  
M Sanna
Keyword(s):  
Vestibular Schwannoma ◽  
Tumour Size ◽  
Internal Auditory Canal ◽  
Hearing Preservation ◽  
Middle Cranial Fossa ◽  
Vestibular Nerve ◽  
Case Review ◽  
Explanatory Factors ◽  
Inferior Vestibular Nerve ◽  
A Prospective Study

AbstractObjective:The origin of vestibular schwannoma has always been a matter of debate. The aim of our study was to identify the nerve origin of this tumour.Study design:Prospective case review. This study was conducted at Gruppo Otologico, a private referral centre for neurotology and skull base surgery.Methods:A total of 200 cases of vestibular schwannoma were included in the study. All the tumours were removed surgically utilising the translabyrinthine approach. The origin of the tumour was sought at the fundus of the internal auditory canal.Results:A total of 200 consecutive cases was included in the study. The origin of the tumour was limited to one nerve at the fundus in 152 cases (76 per cent). Out of these cases, the tumour originated from the inferior vestibular nerve in 139 cases (91.4 per cent), from the superior vestibular nerve in nine cases (6 per cent), from the cochlear nerve in two cases (1.3 per cent) and from the facial nerve in two cases (1.3 per cent).Conclusion:The vast majority of vestibular schwannomas originate from the inferior vestibular nerve; the incidence of involvement of this nerve increases as the tumour size increases. An origin of vestibular schwannoma from the inferior vestibular nerve can be considered as one of the explanatory factors for the poor functional outcome of the extended middle cranial fossa approach, and probably accounts also for the better hearing preservation rate reported in some series for the retrosigmoid approach.

Optical Detection of Developmental Origin of Synaptic Function in the Embryonic Chick Vestibulocochlear Nuclei

2003 ◽  
Vol 89 (6) ◽  
pp. 3215-3224 ◽  
Author(s):  
Katsushige Sato ◽  
Yoko Momose-Sato
Keyword(s):  
Brain Stem ◽  
Nerve Stimulation ◽  
Functional Organization ◽  
Vestibular Nerve ◽  
Synaptic Function ◽  
Cochlear Nerve ◽  
Embryonic Stage ◽  
Excitatory Postsynaptic Potential ◽  
Developmental Origin ◽  
Fast Spike

Functional organization of the brain stem vestibulocochlear nuclei during embryogenesis was investigated using a multiple-site optical recording technique with a fast voltage-sensitive dye. Brain stem slices with the cochlear and/or vestibular nerves attached were dissected from 6- to 8-day-old (E6–E8) chick embryos. Electrical responses evoked by cochlear or vestibular nerve stimulation were optically recorded simultaneously from many loci of the preparations. In E7 and E8 preparations, we identified two components of the optical response with cochlear or vestibular nerve stimulation; one was a fast spike-like signal related to the action potential, and the other was a slow signal related to the glutamate-mediated excitatory postsynaptic potential. The location of the cochlear nerve response area was mainly located on the dorsolateral region, while that of the vestibular nerve was deviated ventromedially. At E6, cochlear nerve stimulation evoked only the fast spike-like signals in normal Ringer solution. However, when we removed Mg2+ from the extracellular solution, significant slow signals were elicited in the E6 preparation. The present results demonstrated that in the chick vestibulocochlear nuclei, functional synapses are already generated by the E7 embryonic stage and that postsynaptic activity related to N-methyl-d-aspartate receptors emerges latently, at least in the cochlear nerve-related nucleus, at the E6 embryonic stage. This chronological sequence of the emergence of postsynaptic function is different from that reported previously (E10–E11), suggesting that the developmental origin of sensory information transfer in the auditory pathway is much earlier than has been anticipated.

Dorsolateral Medullary Infarction: A Neurogenic Cause of a Contralateral, Large-Amplitude Vestibular Evoked Myogenic Potential

2008 ◽  
Vol 19 (03) ◽  
pp. 246-256 ◽  
Author(s):  
Larry Lundy ◽  
David Zapala ◽  
Ketil Olsholt
Keyword(s):  
Brain Stem ◽  
Vestibular Nuclei ◽  
Vestibular Nerve ◽  
Vestibular Evoked Myogenic Potential ◽  
Lateral Medullary Infarction ◽  
Myogenic Potential ◽  
Inferior Vestibular Nerve ◽  
Dorsolateral Medullary Infarction ◽  
Contralesional Side ◽  
Medullary Infarction

The vestibular evoked myogenic potential (VEMP) has become a useful tool to assess the saccule and inferior vestibular nerve function. Vestibulopathies involving the saccule or inferior vestibular nerve typically result in VEMP responses that are diminished or absent on the involved side. Abnormally large VEMPs are rare. Large VEMPs have been associated with superior canal dehiscence, Ménière's disease, and labyrinthine fistula. In all of these cases, the abnormally large VEMP can be explained on the basis of labyrinthine hydromechanical changes that result in excessive saccular displacement in response to intense sound. In this report, a case is presented of a 74-year-old male with dorsal lateral medullary infarction (Wallenberg's syndrome) who presented with an enlarged VEMP—a finding that has not been reported to date as a result of a brain stem lesion. Particularly perplexing, the enlarged VEMP was on the contralesional side. A proposed mechanism of contralateral vestibular nuclei disinhibition secondary to the brain stem stroke is discussed. El potencial miogénico vestibular evocado (VEMP) se ha convertido en una herramienta útil para evaluar el sáculo y la función del nervio vestibular inferior. Las vestibulopatías que involucran el sáculo y el nervio vestibular inferior típicamente generan respuestas del VEMP que están disminuidas o ausentes en lado involucrado. Los VEMP anormalmente grandes son raros. Los VEMP grandes se han asociado con dehiscencia del canal superior, con enfermedad de Ménière y con fístula del laberinto. En todos estos casos, el VEMP anormalmente grande puede explicarse sobre la base de cambios hidromecánicos del laberinto, que producen un desplazamiento excesivo del sáculo, en respuesta a un estímulo sonoro intenso. En este reporte, se presenta un caso de un hombre de 74 años de edad con un infarto medular dorsolateral (Síndrome de Wallenberg), quien mostró un VEMP grande—un hallazgo que a la fecha no ha sido reportado como resultado de una lesión del tallo cerebral. Sorprendentemente, el VEMP agrandado estaba en el lado contrario a la lesión. Se discute un mecanismo propuesto de desinhibición de los núcleos vestibulares contralaterales, producto de la apoplejía en el tallo cerebral.

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