1/12. Is cochlear implantation possible after acoustic tumor removal?HYPOTHESIS: This study aimed to assess the possibility of hearing restoration after acoustic tumor removal. BACKGROUND: hearing restoration surgery may be indicated after surgery of bilateral acoustic tumors or surgery of acoustic tumor in the only hearing ear. The choice is between cochlear implantation and brainstem implantation. methods: From the temporal bone collection at the House Ear Institute, los angeles, the author histologically examined eight temporal bones from seven patients who had undergone acoustic tumor removal during their lifetime. Special emphasis was put on examining the patency of the cochlear turns and on survival of the spiral ganglion cells and cochlear nerve. RESULTS: This study showed that after translabyrinthine acoustic tumor removal, there is progressive osteoneogenesis of the cochlea associated with almost complete degeneration of the spiral ganglion cells and cochlear nerve. Similar findings were noticed after middle fossa removal of acoustic tumor with unsuccessful hearing preservation. CONCLUSIONS: The histologic changes described in the cochlea and cochlear nerve represent the effects of ischemia resulting from inadvertent cutting of the blood supply during acoustic tumor removal. It is possible to do cochlear implantation after acoustic tumor removal provided that the result of promontory electrical stimulation test is positive (the cochlear nerve is intact) and that implantation is done at the time of acoustic tumor removal or shortly thereafter, before cochlear ossification is complete.- - - - - - - - - - ranking = 1keywords = ganglion (Clic here for more details about this article) |
2/12. Electrically evoked auditory brainstem response monitoring of auditory brainstem implant integrity during facial nerve tumor surgery.evoked potentials identified as electrically evoked auditory brainstem responses (EABRs) have been recorded from a patient in response to electrical stimulation of the cochlear nucleus via an auditory brainstem implant. Recording such EABRs during surgery for removal of an ipsilateral facial nerve tumor provided a means to monitor the integrity of the implant. The presence of stable EABRs similar to those obtained before surgery indicated that the lead wires had not been severed and that the implanted electrodes had not been dislodged. EABR recording may also be useful for assisting with positioning the stimulating electrodes during initial implantation surgery, by verifying that stimulation can activate the auditory system.- - - - - - - - - - ranking = 0.072119171570847keywords = nucleus (Clic here for more details about this article) |
3/12. Anatomic examination of a case of open trigeminal nucleotomy (nucleus caudalis dorsal root entry zone lesions) for facial pain.Nucleus caudalis dorsal root entry zone lesions (open trigeminal nucleotomy) are a surgical procedure which can achieve pain control without major complications in the difficult clinical setting of deafferentation-type facial pain. Two patients are reported, who had relief of pain, but also experienced neurological complications. One patient succumbed to pulmonary complications, which provided the opportunity for anatomic analysis of the lesioned area, which is discussed in detail. Potential modifications of the surgical technique are suggested.- - - - - - - - - - ranking = 0.28847668628339keywords = nucleus (Clic here for more details about this article) |
4/12. temporal bone pathology of acoustic neurinoma (unilateral and bilateral) in relation to the internal auditory canal surgery.temporal bone pathology of 3 cases with large unilateral acoustic neurinoma (AN) and 2 cases with large bilateral AN (neurofibromatosis 2; NF2) were studied. One case with unilateral AN was diagnosed as neurofibromatosis 1 (NF1). Unilateral AN had distinct borderlines at the fundus in 5 of 12 examination points between tumor tissues and nerve fibers, but only 1 of 12 was distinct around the porus acousticus. Bilateral AN showed no distinct borderlines at the fundus and around the porus acousticus. These findings suggest that clear separation of the VIIth or VIIIth nerve from large tumors is very difficult, especially in cases of bilateral AN. geniculate ganglion cells of tumor origin on ears were fairly well preserved in 2 cases with unilateral AN and 1 case with bilateral AN. Well preserved geniculate ganglion cells could be dependent on blood supply not from the internal auditory artery.- - - - - - - - - - ranking = 1keywords = ganglion (Clic here for more details about this article) |
5/12. Cerebello-pontine angle paraganglioma simulating an acoustic neurinoma.An unusual case of paraganglioma arising from the internal auditory meatus and growing into the cerebello-pontine angle is reported. Clinical features, pre-operative radiological appearances and intra-operative findings were indistinguishable from those of an acoustic neurinoma. However, the paraganglionic nature of the tumour was confirmed by the electron microscopic evidence of neurosecretory features.- - - - - - - - - - ranking = 0.5keywords = ganglion (Clic here for more details about this article) |
6/12. Histological changes of vestibular nerves and ganglion cells in the acoustic tumor in relation to clinical functions.The superior vestibular nerves and vestibular ganglion cells were observed electron microscopically in acoustic tumors removed surgically from 15 patients. Furthermore, the sensory cells of the vestibular organs were examined. Histological changes of vestibular nerves and ganglion cells were compared with the caloric responses of the patients. In most cases, the degree of degeneration of myelinated nerve fibers was proportional to the reduced responses of vestibular nerves. The myelinated nerve fibers decreased in number and showed some features of demyelination. The alteration of vestibular ganglion cells was unremarkable in comparison with vestibular nerves. In some cases, the number of lipofuscin granules, vacuolar organelles and amorphous materials markedly increased in the ganglion cells. However, the sensory cells of the vestibular organs appeared normal.- - - - - - - - - - ranking = 4keywords = ganglion (Clic here for more details about this article) |
7/12. Electrical stimulation of cochlear nucleus in man.Auditory percepts can be produced by electrical stimulation of the cochlear nucleus in man. The ability to locate accurately and stimulate selectively the cochlear nucleus after removal of an acoustic schwannoma was confirmed in this patient. The surgical approach, electrode design, and a discussion of the results and concerns of electrical stimulation are reviewed.- - - - - - - - - - ranking = 0.43271502942508keywords = nucleus (Clic here for more details about this article) |
8/12. Myoclonic syndrome and dentate nucleus lesion after excision of giant acoustic neurinoma.The authors describe one case of a Myoclonic syndrome appeared after the excision of a giant acoustic neurinoma. On the basis of autoptic studies, Myoclonic Syndromes, similar to the one reported here, have been shown to be associated to lesions of the Dentate Nucleus. Cranial computed tomography indicates, in our case, a cerebellar lesion localized in the Dentate Nucleus region. This figure allows the authors to correlate "in vivo" the anatomo-clinical data.- - - - - - - - - - ranking = 0.28847668628339keywords = nucleus (Clic here for more details about this article) |
9/12. Surgery of the skull base.Tumors involving the base of the skull are often occult and may become quite large before detection is possible. Symptomology varies depending upon the nature of the tumor and its placement. These neoplasms have frequently been considered inoperable simply because of their location, but in recent years microsurgical technique and high speed air drills have allowed the modern temporal bone surgeon to gain improved access to the skull base. A wide variety of surgical approaches to tumors in this area have been described in the past 20 years: translabyrinthine, middle fossa, transcochlear, retrolabyrinthine, retrosigmoid, transpalatal-transclival, and through the jugular bulb. The purpose of this paper is to review the indications, complications, and results of each of these procedures in relation to specific tumors involving the skull base. case reports illustrate the diagnosis and surgical management of a variety of unusual neoplasms, including an extradural meningioma of the temporal bone and clivus, a low grade squamous cell carcinoma on the tegmen in a radical cavity, a large primary cholesteatoma, an osteoblastoma of the temporal and occipital bones, an XIth nerve neuroma in the jugular bulb area, and an osseous hemangioma involving the facial nerve at the geniculate ganglion.- - - - - - - - - - ranking = 0.5keywords = ganglion (Clic here for more details about this article) |
10/12. Human vestibular nerve morphology and labyrinthectomy.Surgical labyrinthectomy leads to extensive and degenerative changes in the membranous labyrinth and is often followed by fibrosis and ossification of the vestibule and neuroma formation. After labyrinthectomy the distal processes of the vestibular nerve degenerate, but the nerve trunk within the internal auditory canal, including Scarpa's ganglion, does not show an obvious loss of neurons. Electron microscopic examination of the cells of Scarpa's ganglion revealed many changes similar to those of chromatolysis, indicating increased cell metabolism and probable regenerative changes. Many nerve fibers appeared to be in the process of regeneration. Some ganglion cells were fibrotic and showed ultrastructural features similar to those of cells that had undergone atrophy but survived in a sublethal state.- - - - - - - - - - ranking = 1.5keywords = ganglion (Clic here for more details about this article) |
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