[Tullio phenomenon after cochlear implantation]. / Tullio-Phänomen nach Kochlearimplantation.

The Tullio phenomenon is defined as an acoustically inducible vestibular disorder that was first described in 1929. In an animal experiment Tullio provoked acoustic oscillations at the labyrinth followed by signs of imbalance. In the literature this phenomenon can be found in healthy but sensitive persons as well as in patients with Meniere's disease and patients with lesions between the stapes, footplate and the membranous labyrinth caused by fractures, stapes dislocations, labyrinthitis or perilymphatic fistulas. In this case report a patient complained about vertigo after cochlear implantation provoked by acoustical stimulation at a sound pressure level above 90 dB independent of the cochlear implant (CI). During tympanoscopy we found scar tissue surrounding the ossicles after CI. After disconnecting the ossicular chain no vertigo or nystagmus could be provoked. After CI regular ENT examinations and appropriate explorations of postoperative complaints are necessary. Vertigo especially requires very careful diagnostic procedures.

Nucleus double electrode array: a new approach for ossified cochleae.

INTRODUCTION: The ossified cochlea is still a special surgical issue that requires a special surgical procedure. The current cochlear implants only have one electrode lead, which can be placed only partially in the drilled out basal turn. The small number of used active electrodes leads to worse performance as compared with patients with full insertion. METHODS: To overcome this limitation, a special electrode was developed consisting of two arrays. One array with 11 active electrode rings is placed in the drilled out basal turn, the second array with 10 active electrodes in the opened second turn. The number of inserted electrodes can be significantly increased. The surgery is similar to that in nonossified cochleae. After the posterior tympanotomy, the bridge is removed and the incus is located. A cochleostomy is performed at the basal turn and the new-built tissue removed. A second cochleostomy is placed below the cochleariform process. In most cases, the second turn is not obliterated and the second electrode array can be fully inserted. RESULTS: The surgical procedure was in all nine cases uneventful. Intraoperative stapedius reflex could be recorded with elevated thresholds. The wide variety of stimulation modes and sites allows an individual fitting to maximize the performance. All patients show a gap in the pitch scale between the apical and the basal array. The pitch variation is much smaller in the apical array. All patients have some benefit from the additional apical array and an improved performance. CONCLUSION: The nucleus double electrode array is an advanced treatment option for patients with ossified cochleae. The receiver/stimulator is a regular nucleus cochlear implant.

Comparison of preoperative electrostimulation data using an ear-canal electrode and a promontory needle electrode.

OBJECTIVE: To compare the electrical stimulation results of the ear-canal electrode with those of a promontory needle. PATIENTS AND METHODS: In thirty-three adult patients, the ear-canal electrode test was compared with the needle electrode promontory test with respect to sound perception, rhythm detection, frequency, and disturbing side effects. RESULTS: The ear-canal electrode test, in comparison with the needle electrode promontory test, resulted in vibrotactile sensation in addition to auditory sensation in some patients, less auditory fatigue, higher threshold levels, and lower discomfort levels. CONCLUSION: Reliable assessment of deafness in children requires, in addition to electrical stimulation, determination of the electrical evoked auditory brainstem response with the patient under anesthesia.

Intraoperative test of auditory nerve function.

OBJECTIVE: To develop a preoperative objective test of auditory nerve function for the assessment of cochlear implant candidacy, especially in children. PATIENTS AND METHODS: We stimulated electrically with a ball electrode before insertion of the implant. First the stimulus was applied bipolar between the promontory and the round window. To record auditory brain stem responses (EABRs) very high stimulus intensities were needed, which was not possible in all patients. RESULTS: By stimulation in the basal turn of the cochlea, evoked potentials could be derived. Although in some patients the facial nerve was stimulated as a side effect, auditory evoked potentials could be recorded. A facial muscle artifact can be differentiated from the EABRs by latency and the slope of the input-output function. CONCLUSION: For the present, the only reliable test seems to be the EABR recording stimulated within the cochlea.

Monitoring the electrode position during acoustic neuroma surgery.

OBJECTIVE: To obtain information about the auditory brain stem responses during auditory brain stem implantation. SETTING: Operating room during acoustic neuroma surgery. METHODS: Electrical stimulation of the auditory system during acoustic neuroma surgery, by placement of a monopolar or bipolar electrode on the nerve or nerve entry zone of the brain stem, and monitoring of the evoked auditory brain stem responses (EABR) recorded from the scalp. In some patients, a multichannel silicon electrode array was placed at the foramen of Luschka. Biphasic rectangular current pulses were applied, and EABRs were recorded. RESULTS: Usually the derived potentials consisted of three peaks with a latency below 4 ms. Sometimes we got a complex of two or more peaks. The interpeak interval between the first and second peak was about 0.7 to 1.0 ms, independently of the stimulating electrode position, but the absolute latency of the first peak increased from a minimum of 0.7 ms stimulated at the foramen of Luschka to a maximum of 1.3 ms stimulated at the nerve.

[Cochlear implant management of young children]. / Die Cochlear-Implant-Versorgung bei Kleinkindern.

INTRODUCTION: Since 1988, more than 450 children have received cochlear implants at the Department of Otolaryngology of the Medizinische Hochschule Hannover. Among them are 38 children who underwent surgery before the age of two. Due to increasing experience with this technique, the mean age at implantation has decreased over time so that most children nowadays receive implants between the ages of two and five. In terms of the critical periods of both development of the auditory system and the acquisition of language, it is advantageous for even younger children to receive implants soon after detection of deafness. However, the present diagnostic tools do not allow proper estimation of residual hearing and additional handicaps. Therefore longer periods of hearing aid use and audioverbal training are mandatory before implantation. Additional objections against early implantation are biosafety problems such as head growth, the high incidence of otitis media, and the specific surgical anatomy. This paper outlines criteria for patient selection, the surgical concept, postoperative rehabilitation, and complications. PATIENTS: Twenty-six children suffered from postmeningitic deafness and beginning obliteration of the cochlea as shown by repeated high resolution CT scans. Nine children had congenital deafness which was detected early in life and showed no improvement after proper hearing aid fitting and audioverbal training for speech development. Three children had severe inner ear malformations detected by CT scans. All children had no ABR or CAP responses in ECoG. Their developmental, language, and neuropaediatric status was examined. SURGERY: Thirty-five children received the Nucleus Mini 22 cochlear implant; three children received the Clarion 1.2 device. The surgery was not different from adult surgery. Special care was given to proper fixation and placement of the electrode in the drilled out mastoid to compensate for head growth. POSTOPERATIVE RESULTS: All children wear the speech processor regularly. They are able to detect everyday sounds and suprasegmental features of speech after a few months. After one year, the child begins to understand and produce speech; after two years speech understanding has been achieved and normal language development starts with small sentences. The complication rate was not higher than in other age groups of patients. Fitting and tune-up of the speech processor required a broad range of experience and a specialized team working at the children's implant center. CONCLUSION: Early implantation in children is both possible and effective in selected cases. Due to an improved early detection of deafness, it should be possible to increase the percentage of children with early cochlear implantation.