[Concept and anatomical feasibility study of an "endosteal electrode" for bimodal stimulation in severely deaf ears]. / Konzept eines "endostealen" Cochlear Implant-Elektrodenträgers für Patienten mit Restgehör und Machbarkeitsstudie aus anatomischer Sicht.

BACKGROUND: Many patients with severe hearing loss could benefit from a bimodal stimulation unilaterally: acoustically in the apical region of the cochlea with some residual low frequency hearing and electrically via a cochlear implant in the basal turn with lost high hearing in the high frequency range. As a new concept we introduce the idea of an "endosteal electrode" - to be inserted between spiral ligament and endosteum of the bony wall without opening the fluid-filled inner ear. In this paper the feasibility from the anatomical point of view is to be proven. MATERIALS AND METHODS: In 10 human temporal bone specimens the bone covering the membraneous inner ear is carefully removed in the site of a typical cochleostomy. It should by proven whether or not the soft tissue layer covering the inner ear could be left intact and, furthermore, whether a "dummy-electrode array" could be inserted "endosteally". RESULTS: In 10 of the 10 specimen the preparation could be carried out in the desired way, leaving the spiral ligament intact. The regular site of the "electrode" was morphologically proven after embedding the specimens for histological evaluation. CONCLUSIONS: From the anatomical point of view, an "endosteal cochlear implantation" seems feasible. Further experiments including animal studies must show, whether this concept might succeed functionally.

[What are the side-effects of nocturnal continuous positive pressure ventilation (nCPAP) in patients with sleep apnea for the head-neck region?]. / Welche Nebenwirkungen hat die nächtliche kontinuierliche Uberdruckbeatmung (nCPAP) bei Schlafapnoikern im Kopf-Hals-Bereich?

BACKGROUND: Nasal continuous positive airway pressure ventilation therapy is the present gold standard in the treatment of obstructive sleep apnea. Depending on the definitions used, about 60% of the patients tolerate nCPAP therapy. The reason for this limited tolerance is a varying number of side effects. The aim of the present retrospective study was to analyze the incidence and intensity of otorhinolaryngological side effects of nCPAP therapy. METHOD: Questionnaires inquiring about the frequency of using nCPAP and objective and subjective complaints were sent to 92 patients who were treated with nCPAP in our department within the last years. Six of 92 patients also used a heated humidifier. A telephone interview was added to complete the questionnaires as correctly as possible. RESULTS: Eighty questionnaires were sent back completely answered. The mean frequency of using nCPAP (+/- standard deviation) was 6.8 +/- 1.6 hours per night and 6.5 +/- 1.4 nights per week. The mean duration of nCPAP therapy was 28.0 +/- 21.0 months; the mean pressure used was 6.8 +/- 1.2 cm H2O. The following side effects were specified most frequently: disturbance of sleep during the night (71.3%), dry mouth (47.5%), dry nose (46.3%), pressure marks by the mask (41.3%), crusts within the nasal cavity (38.8%), and hearing loss (26.3%). Dryness within the nose and mouth was considered the most irritating side effects. CONCLUSIONS: NCPAP therapy has a number of different side effects in the head and neck. These side effects are seen frequently. Prospective analysis must show whether there are correlations between the intensity and frequency of side effects and the duration of therapy, and whether technical improvements (quality of masks, noise reduction, humidifiers) are able to reduce the frequency of side effects.

Preconditions of language development in deaf children.

The harmful effects of childhood hearing impairment are given little thought by many people because hearing loss is largely an invisible handicap. An infant with a hearing impairment is generally healthy-looking and develops relatively normally during the first year of life. Hearing impairment in infants interferes with the normal development of spoken language. We are biologically programmed to develop certain skills in response to certain inputs. Language learning is one such skill which must be gained very early in life. Hearing is the most important basis for normal language acquisition and language is the keystone of modern society. Hearing loss must be identified as early as possible in the first years of life, especially a child with profound or severe hearing loss must be identified in the first year of life. If not, the child has missed an irreversible sensitive phase for learning of speech and language.

Morphologic study of the guinea pig cochlea after cochlear implantation using the "soft surgery" technique.

Clinical and experimental data appear to indicate that by means of an extremely gentle procedure, known as the "soft surgery" technique, during the insertion of the electrode carrier of the cochlear implant, some level of existing residual hearing can be preserved. By means of an animal model, morphologic changes in the organ of Corti after use of this atraumatic implantation technique were investigated with two types of implants and the results compared. Insertion of the implants was facilitated by lubrication with Healon. In the scanning electron microscopy picture of the organ of Corti, only minor changes in the outer hair cells were observed. As an obligatory reaction of the cochlea to the intracochlear implant, a connective tissue envelope was found around the electrode carrier.

[Morphologic study of the guinea pig cochlea after insertion of cochlear prosthesis electrode materials]. / Morphologische Untersuchung der Meerschweinchen-Cochlea nach Insertion von Elektrodenträger-äquivalenten Materialien.

Experience has shown that a special cochlear-implant procedure, the so-called "soft surgery technique", may help to retain the remaining function of the inner ear. The morphological changes in the organ of Corti after an atraumatic implant procedure were examined using an animal model. The insertion was facilitated by coating the electrode with Healon. Scanning electron microscopy of the organ of Corti revealed only minor changes in the inner and outer hair cells. In all cases connective tissue was found sealing the implant as a reaction of the cochlea to the intracochlear implant.

[Sudden deafness--a form of acute hearing loss]. / Der Hörsturz--eine Form der akuten Schwerhörigkeit.

By idiopathic sudden deafness is meant solely sudden sensory loss of hearing, the pathological-anatomical substrate of which is thought to be acute, vascular endolymphatic hydrops of unknown cause. Sudden deafness always affects one ear only, tinnitus and temporary vertigo may be accompanying symptoms. Sudden loss of hearing reflecting an inner ear involvement of general diseases must be distinguished from sudden deafness as defined above, as also from psychogenic deafness, central-neural deafness during the course of multiple sclerosis, sensory hearing loss in Cogan's disease or syphilis. The same applies to tumours of the inner ear or cerebellopontine angle, which may also present in the form of acute unilateral deafness. Treatment--wherever possible on an inpatient basis--of sudden deafness should be initiated immediately in parallel with a targeted diagnostic workup.

An integrity test battery for the Nucleus Mini 22 Cochlear Implant System.

The probability of system failures increases as the number of cochlear implants increases throughout the world. Whether a malfunction is a technical or physiological problem remains to be defined, particularly in very young children, while a psychogenic hearing disorder after implantation must not be excluded in adults. The battery of objective measurements used clinically at the Medizinische Hochschule, Hannover has provided useful diagnostic information for distinguishing possible causes of failure. In a normally functioning device, an electrical signal equivalent to the biphasic rectangular stimulation pulse can be recorded by measuring skin potentials from surface electrodes placed on the mastoid of the implant side and the forehead. The signal from the stimulated implanted electrodes is derived by applying a constant pulse rate. Signal averaging is not necessary. If no signals are observed, a non-functioning device should be suspected. If the device works normally, function of the auditory pathways can be examined by recording the electrically elicited stapedius reflex or electrically evoked brain-stem responses. In our experience with more than 450 cochlear implant patients, eight internal device failures occurred, while an additional three patients had either reduced or no hearing sensations due to a disorder of the auditory pathways.

[Cochlear implant for children: indications and surgical aspects]. / Das Cochlearimplantat bei Kindern: Indikation und chirurgische Aspekte.

Since the late 80s cochlear implants (CI) have proved to be an efficient means to help bilaterally profound deaf patients. The CI is supposed to replace the function of the inner ear. A CI-system consists of an externally worn speech processor and the implants itself with intracochlear electrodes. A preoperative promontory test serves to differentiate between inner ear deafness and non-functioning hearing nerve, but is performed only in the case of adults. In small children results of electrocochleography form the basis for such an assessment. CI-surgery in small children is basically not more complicated than in adults. Whereas cochlear implants in adults are only indicated for late-deafened patients, both small children deafened after having acquired speech as well as deaf born children can learn to understand and develop speech. However, consistent technical and pedagogical rehabilitation is an indispensable prerequisite for success. This is being done in Hannover in a special children-like rehabilitation center where children and 1 parent are trained in-house for 12 times once a week. Results are the better, the shorter the duration of deafness, i.e. if children are implanted already during the 3rd year of age, and deafened children - mostly after meningitis - immediately, if possible. Some children even achieve to develop spontaneous speech with elements of dialects and a nearly-unimpaired level of understanding.

[Acute hearing loss caused by arterial hypotension]. / Akute Hörminderung durch arteriellen Hypotonus.

The aim of this study was to confirm the hypothesis based on clinical observations of a causal relationship between arterial hypotension and sudden hearing loss of lower frequencies. A noninvasive system was used that enables repeated blood pressure measurements at programmable time intervals. With this method 24-hour blood pressure monitoring was performed on 81 patients with sudden inner ear hearing loss proved by audiological tests (and in part defined by magnetic resonance imaging). The profiles of the circadian blood pressures recorded actually revealed a significant incidence of low-frequency hearing loss of up to 30 dB HL in the patient group suffering from arterial hypotension compared to those showing normal blood pressure or hypertension. In the patient group designated arterial hypotension may be the probable cause for sudden hearing impairments and should be regarded as a circulatory disorder with certain implications for management.

[Intracochlear placement of cochlear implant electrodes in soft surgery technique]. / Intrakochleäre Plazierung der Cochlear-Implant-Elektroden in soft surgery technique.

It is commonly accepted that the intracochlear placement of the cochlear implant electrode is potentially damaging to the hearing rests which may exist. Consequently, cochlear implants have been recommended for totally deaf ears only. The question has been raised whether or not it is possible to preserve residual hearing during intracochlear implantation through extremely careful surgical techniques. Experience has shown, that the cochleotomy of the scala tympani anterior to the round window niche, careful preservation of the fibrine endost layer and the use of Healon are amongst the surgical procedures described which may assist in retaining the rest function of the inner ear. These observations which are discussed in detail suggest that the experienced surgeon can effect preservation of residual hearing for patients who cannot derive significant benefits from conventional acoustic amplifiers.

[Correlation between electrically-induced stapedius reflex and discomfort threshold in cochlear implant patients]. / Beziehung zwischen dem elektrisch ausgelösten Stapediusreflex und der Unbehaglichkeitsschwelle bei Cochlear-Implant-Patienten.

Electrically elicited stapedius reflex thresholds are an objective criteria for the fitting of speech processors in very young children. Reflex thresholds generally fit well within the upper third of a subject's individual dynamic range, the difference between electrical threshold of hearing, (T) and maximum comfort (C) levels and can be used to predict ultimate behavioral maximum comfort levels. In acoustically elicited stapedius reflexes a saturation of impedance amplitude can be registered at approximately 110 dB, which is 90% of the dynamic range. Assuming a similar relationship for the electrically elicited stapedius reflex there would be two values within the dynamic range which could be used for extrapolation of the threshold level. In the present study, the electrically elicited stapedius reflex was examined in 16 deaf patients who had received 22-channel Clark/NUCLEUS cochlear implants. Using an apical, a medial and a basal electrode pair, different stimulation positions within the cochlea were tested. The contralateral reflexes could be elicited in 11 patients (69%). A saturation of the reflex amplitude was recordable in 10 subjects, at least in one of the electrode pairs. The reflex saturation in all cases was located close to the uncomfortable loudness level within the subjects' dynamic ranges (at 95% dynamic). This finding is comparable to acoustic matter. As a result, these data together with reflex threshold data suggest a means for predicting to predict the threshold levels.