Extended approaches to the skull base in CP-angle and surrounding structures
Madjid Samii
International Neuroscience Institute, Hannover, Germany
The retrosigmoid is the main approach to the CP-angle and surrounding structures. Its flexibility and panoramic view allow removing safely most lesions developing in that area. Some tumors, however, tend to extend beyond the CP-angle – e.g., in the supratentorial space, Meckel’s cave or into the petrous bone. In these cases, an extension of the classical retrosigmoid approach might be utilized. In this lecture, the technique and advantages of the retrosigmoid suprameatal, retrosigmoid transtentorial or the retrosigmoid inframeatal approaches will be presented.
Keywords: CP-angle, retrosigmoid approach, retrosigmoid suprameatal approach, retrosigmoid transtentorial approach, retrosigmoid inframeatal approach
Surgery of facial nerve
Madjid Samii
International Neuroscience Institute, Hannover, Germany
The facial nerve might be involved and affected by numerous pathological conditions, either primarily or secondarily. The topic of the lecture is their surgical treatment, in particular the management of tumors originating from the nerve, such as facial schwannomas. The technique for facial nerve preservation in case of surgery of lesions, secondarily involving the nerve, will also be presented and illustrated. In case of complete facial nerve palsy, the function of the nerve should be restored. The techniques for facial nerve reanimation or reconstruction will be described. The direct end-to-end facial nerve anastomosis, with or without a sural nerve interposition graft, leads to the best functional outcome, but can be rarely applied. In our experience, the most commonly utilized procedure to restore movement to the facial muscles is the hypoglossal-facial nerve end-to-side anastomosis.
Keywords: facial nerve palsy, facial nerve schwannoma, vestibular schwannoma, hypoglossal-facial nerve anastomosisç
Vestibular implants: future in vestibular treatment
Angélica Pérez Fornos
Western Switzerland Cochlear Implants Center, Geneva University Hospitals, University of Geneva, Switzerland
Vestibular implants are implantable devices that attempt to partially restore vestibular function in patients with severe bilateral vestibulopathy of peripheral origin, using electrical currents. There have been substantial research efforts, first in animals and more recently in humans, towards the development of vestibular implants. Our group, the Geneva-Maastricht team, developed an original concept based on a modified cochlear implant. This device, developed in close collaboration with MED-EL (Innsbruck, Austria), provides 1 to 3 extra-cochlear electrodes which are implanted in the vicinity of vestibular afferents in addition to the cochlear implant array. We started implantations in humans in 2007 and, to date, 13 patients with severe bilateral vestibulopathy were implanted with these prototype devices, without surgical or medical complications. Special surgical techniques have been developed for safe implantation of these devices and their feasibility has been demonstrated in human subjects. Humans have demonstrated surprising adaptation capabilities to the artificial vestibular signal. Successful restoration of the vestibulo-ocular reflex in the mid- to high-frequency range has been demonstrated using standard clinical tests (rotatory chair and video-head impulse test). We also showed that it is possible to activate the vestibulo-collic reflex using measures of cervical myogenic vestibular evoked potentials. Controlled postural responses could also be obtained with our prototype vestibular implant device. Finally, visual abilities in dynamic settings were restored with the vestibular implant. The latter is a major step forward, providing the first ever demonstration of useful rehabilitation of this patient population. The results obtained so far in humans are very encouraging. We hope that the increasing interest in this field and the substantial research efforts allocated will lead to a clinical application in the near future. It should also be mentioned that the vestibular implant opens new possibilities for exploring several fundamental issues: balance function, the adaptive capacities of the brain, the processes of temporal integration of sensory information necessary for equilibrium, and probably for better understanding vestibular physiology and vestibular disorders. Therefore, the vestibular implant opens new perspectives, not only as an effective therapeutic tool, but also pushes us to go beyond current knowledge and well established clinical concepts.
Keywords: bilateral vestibular loss, vestibular implant, cochlear implant, electrical stimulation, neuroprosthesis, neurostimulation, perception, vestibulopathy, vestibulo-ocular reflex, vestibulo-collic reflex, vestibulo-spinal reflex, vestibular function