Objectives. Efforts towards the development of a vestibular implant are being made. To mimic the physiology of the vestibular system, such a device must be first capable to restore a baseline or "rest" activity in the vestibular pathways and then to modulate it according to direction and velocity of head movements. The aim of this study was to assess whether a human subject could adapt to continuous electrical stimulation of the vestibular system, and if it was possible to elicit artificially oscillatory smooth eye movements via modulation of the stimulation. Conclusions.While this is a case study on one patient, results suggest that humans can adapt to electrical stimulation of the vestibular system without too much discomfort. Once in the adapted state, the electrical stimulation can be modulated to artificially elicit smooth eye movements. Therefore, the major prerequisites for the feasibility of a vestibular implant for human use are fulfilled.

Objectives. Recently, we demonstrated that it was possible to elicit vertical eye movements in response to electric stimulation of the posterior ampullary nerve. In order to develop a vestibular implant, a second site of stimulation is required to encode the horizontal movements.Methods. Three patients suffering from a disabling Menière's disease were included in the study. Before a labyrinthectomy via a standard transcanal approach was performed, their lateral and anterior ampullary nerves were surgically exposed under local anesthesia through a procedure we recently developed. The attic was opened, the incus and malleus head removed, and a small well drilled above the horizontal portion of the facial canal to place an electrode. This electrode was used to deliver balanced biphasic trains of electric pulses.Results. Electric stimuli elicited mainly horizontal nystagmus without simultaneous stimulation of the facial nerve. Conclusions.It is possible to stimulate electrically the lateral and superior ampullary nerves without simultaneous stimulation of the facial nerve. As both nerves run close to each other, electric stimulation provoked eye movements that were not purely horizontal but had also some vertical components. Nevertheless, this site can be used to encode horizontal movements because central adaptation may correct unnatural afferent vestibular cues delivered by a prosthetic sensor. The range of stimulus intensities producing a response was broad enough to envision the possibility to encode eye movements of varying speeds.

We analyzed the results of 604 cases of primary stapes surgery performed between 1974 and 1997 with replacement of the stapes by a 0.6- or 0.8-mm Schuknecht Teflon-wire piston. At long-term follow-up (1 to 21 years; mean, 7 years), the residual air-bone gap was 10 dB or less in 79% of the cases. The hearing results and postoperative complications were comparable to those reported by authors who used the same evaluation criteria. Although the aim of the surgery was to perform a small stapedotomy with a narrow footplate perforation (0.8 mm), a large stapedotomy or a stapedectomy was performed in 134 cases (22.2%) because of surgical or anatomic conditions. Our results show that the larger footplate perforations allowed a better correction of the air-bone gap at the lower frequencies. The ears with larger perforations did not show a higher incidence of sensorineural hearing loss.

The objective of this study was to evaluate, over the long-term, the anatomic and functional outcome of canal wall-down mastoidectomy performed for chronic otitis media with cholesteatoma and chronic otomastoiditis resistant to all conservative treatment. The study was made through a retrospective review of 338 cases of consecutive primary canal wall-down mastoidectomies performed between 1974 and 1998. Included were 259 cases with sufficient data. In all cases, functional reconstruction was performed at the same time as the mastoidectomy. Demographic and clinical data were collected from each file. From the clinical data, the surgical techniques, complications, the number of follow-up visits necessary to ensure cavity cleanliness, details of care provided over the period 1 to 24 years (mean, 7 years) after the operation, and audiometric data from admission and from the latest postoperative follow-up were retained. Canal wall-down mastoidectomies were followed up an average of 10 times during the first 6 months after operation, twice a year over the 6-year period following surgery, and less than twice a year beyond the 6-year period. Care was dispensed for meatal stenosis, scars, infections, polyps, and beads of cholesteatoma. Surgical revisions were performed because of residual or recurrent cholesteatoma in 6.1% of the cases, because of perforation of the tympanic membrane in 7.3% of the cases, and to improve hearing in 12.2% of the cases. At the last consultation, 1 to 24 years after surgery, cavities were found to be dry and self-cleaning in 95% of the cases, and still humid, with otorrhea, in 5% of the cases. Over the long-term, the hearing threshold remained unchanged in 41.3% of the cases. It was improved after surgery by 10 to 19 dB in 15.4% of the cases, by 20 to 29 dB in 11.5% of the cases, and by more than 29 dB in 3.8% of the cases. The hearing threshold was thus improved or at least remained unchanged in 72.0% of cases. Hearing losses occurred in 28% of the cases: by 10 to 19 dB in 11.9%, by 20 to 29 dB in 6.5%, and by more than 29 dB in 9.2% of the cases. A sensorineural hearing loss of more than 60 dB at all frequencies occurred immediately after the operation in 2 cases (0.7%). There was 1 case of facial paralysis (0.3%). Four patients (1.5%) complained of persistent vertigo. Canal wall-down mastoidectomy is an adequate treatment for chronic otitis with cholesteatoma or chronic otomastoiditis. The anatomic and functional results are satisfactory, and the rate of complications is acceptably low. A tympanoplasty can be performed simultaneously. Thus, for the large majority of patients, only a single intervention is required; however, a small minority can benefit from a revision tympanoplasty. In order to obtain these results, both the patient and the surgeon should engage in a long-term follow-up.

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