BAHA Attract to Osia conversion patients: comparison of the two systems and long-term outcomes.

OBJECTIVE: Osia is a new, transcutaneous, active bone-conduction implant. This study aimed to compare the BAHA Attract and the first-generation Osia system after BAHA Attract to Osia conversion surgery. METHOD: Five patients who had previously used the BAHA Attract system were converted to the first generation of the Osia system. Surgical aspects of the two different systems, audiological performance and subjective opinions of the patients were investigated. Pure tone audiometry and speech audiometry in quiet was performed with each patient's BAHA 5 sound processor on Attract, and the test battery was repeated six weeks after the Attract to Osia conversion and at different time points after the first fitting. Details of the surgery and patients' feedback were analysed. RESULTS: Audiology tests showed significant improvement when using either system; however, the Osia system performance was better. Based on patient feedback, all the five implantees preferred the Osia system. CONCLUSION: The study results suggest that the Osia system is a safe and powerful hearing implant that provides good clinical outcomes.

Early experience on a modern, thin cochlear implant family. A retrospective, international multicenter study.

RATIONALE: Cochlear implantation is the most effective method of rehabilitation for patients with severe to profound sensorineural hearing loss. Binaural hearing forms the basis of the development of hearing-associated cortical networks in infants and toddlers, but simultaneous bilateral implantation is often postponed due to the demands of classical surgical methods, which are associated with large incisions and a deep bony well. OBJECTIVE: The authors report on the use of a modern, thin implant type and the possibilities it provided to simplify the surgical technique. METHODS AND RESULTS: Recent models of the Cochlear™ Nucleus® implant family were studied in an international retrospective multi-center study: 6 otolaryngologists in 5 centers shared their experiences on 73 consecutively implanted, thin implants. The surgical incision could be made shorter than before and only shallow bony wells or none at all were created in 4 out of 5 centers. No complications occurred. DISCUSSION: This study underlines that implants with thin electronics capsules enable a simplified, fast and safe implantation procedure that allows simultaneous bilateral cochlear implantation.

Normative findings of electrically evoked compound action potential measurements using the neural response telemetry of the Nucleus CI24M cochlear implant system.

One hundred and forty-seven adult recipients of the Nucleus 24 cochlear implant system, from 13 different European countries, were tested using neural response telemetry to measure the electrically evoked compound action potential (ECAP), according to a standardised postoperative measurement procedure. Recordings were obtained in 96% of these subjects with this standardised procedure. The group results are presented in terms of peak amplitude and latency, slope of the amplitude growth function and ECAP threshold. The effects of aetiological factors and the duration of deafness on the ECAP were also studied. While large intersubject variability and intrasubject variability (across electrodes) were found, results fell within a consistent pattern and a normative range of peak amplitudes and latencies was established. The aetiological factors had little effect on the ECAP characteristics. However, age affected ECAP amplitude and slope of the amplitude growth function significantly; i.e., the amplitude is higher in the lowest age category (15-30 years). Principal component analysis of the ECAP thresholds shows that the thresholds across 5 electrodes can be described by two factors accounting for 92% of the total variance. The two factors represent the overall level of the threshold profiles ('shift') and their slopes across the electrode array ('tilt'). Correlation between these two factors and the same factors describing the T- and C-levels appeared to be moderate, in the range of 0.5-0.6.

Distortion-product otoacoustic emission (DPOAE) following pure tone and wide-band noise exposures.

The aim of our investigations was to determine how the intensity of distortion-product otoacoustic emission (DPOAE) changes following different sound and noise exposures. We performed examinations on 20 healthy people with normal hearing. DPOAEs were recorded scanning the 0.5-6 kHz frequency interval before and after the exposures. We exposed the subjects to 0.5, 1, 2, 4 and 6 kHz pure tones and wide-band noise (intensity: 80 dB HL, duration: 3 minutes). We conclude that the amplitudes of DPOAEs changed immediately after exposures at most frequencies. DPOAE intensities decreased at some frequencies in the middle frequency range (1-2 kHz), and increased at low and particularly at high frequencies.

Brainstem auditory-evoked potential examinations in diabetic patients.

Brainstem auditory-evoked potential (BAEP) examinations were performed in 15 patients with long-standing type-1 diabetes mellitus (DM). Cardiovascular reflex tests were applied for assessment of autonomic neuropathy. The aim of our investigation was to compare the BAEP results of this patient group with controls and to look for a possible correlation between the alteration of the auditory brainstem function and the cardiovascular autonomic neuropathy. Analysis of the latencies (waves I, II, III and V) and the inter-peak latencies (waves I-III and I-V) of BAEPs revealed a significant difference between diabetics and healthy controls. The amplitudes of waves I, III and V were definitely lower in comparison with those of healthy controls. A positive correlation was observed between the overall autonomic score and the latencies (waves III and V) and inter-peak latencies (waves I-III and I-V). These data support the hypothesis that long-standing DM and diabetic neuropathy might be related as a cause of certain dysfunctions of the central auditory pathways.

Cochlear implantation in osteogenesis imperfecta.

A case is reported in which a Nucleus 22 channel intracochlear implant was applied to a Hungarian woman (age 50 yr) with profound deafness associated with osteogenesis imperfecta. Successful intracochlear insertion of the 22 electrodes resulted in a 70 dB hearing improvement at frequencies 250-2000 HZ. Nevertheless, a characteristic facial twitching appeared upon activation of electrodes 9-13. Inactivation of these electrodes abolished the non-acoustic nerve excitation with preservation of acoustic performance. Osteogenesis imperfecta may involve a state of risk for non-acoustic nerve activation in cochlear implant patients possibly resulting from a reduced impedance to current spread by abnormal bone tissue. This, however can be overcome by simple programming manoeuvres.

Cochlear implantation in a patient with grand mal epilepsy.

A case is reported in which a Nucleus 22 channel intracochlear implant was used to treat a deaf Hungarian woman (aged 37 years) with a 34-year history of grand mal (GM) epilepsy maintained on carbamazepine-diazepam combination therapy who had not benefited from conventional hearing aids. Pre-operative electrical stimulation of the acoustic nerve, however, exhibited a good nerve function with no evidence of abnormal waveforms in the electroencephalogram (EEG). Successful intracochlear insertion of the 22 electrode resulted in a 40 dB hearing improvement at frequencies 250-2000 Hz in the implanted ear with no signs of pathologic wave activity at either the previously recognized epileptic focus (fronto-precentral region) or indeed, in other regions of the brain at use of the implant. We conclude that intracochlear implantation per se is not a hazardous intervention in patients with fronto-precentral epileptic foci.

Cochlear implantation of a Hungarian deaf and blind patient with discharging ears suffering from Behçet's disease.

A case is reported in which a Nucleus 22 channel intracochlear device was implanted a deaf/blind Hungarian adult with discharging ears suffering from Behçet's disease. Preconditioning surgery was employed three months prior to the implantation procedure to ensure a sterile, dry protected environment for the electrodes. One month after implantation, the patient exhibited excellent auditory discrimination capability at the time of the first switch on. We suggest that some deaf/blind individuals may serve as very good candidates for intracochlear implantation.

The prognostic value of facial nerve conduction velocity in patients with Bell's palsy.

The facial nerve conduction velocity was measured in 30 healthy subjects (60 sides) and in 51 patients with a unilateral Bell's palsy. The normal value was 47.8 +/- 5.1 m/s. Incomplete recovery was common in Bell's palsy when the velocity was below 30 m/s. Mild synkinesis was observed in only one patient when the nerve conduction velocity was above 30 m/s. When the degree of degeneration revealed by electroneuroneography did not exceed 60%, the conduction velocity was in the normal range. For degrees of degeneration in excess of this, the conduction velocity decreased in parallel with the increase in the degree of degeneration.

Involvement of glibenclamide-sensitive potassium channels in vasorelaxation by cochlear nerve stimulation.

Rabbit aortic rings relaxed with an increase in cyclic guanosine monophosphate and cyclic adenosine monophosphate content in response to exposure to organ fluid of isolated cochleas of the guinea pig following field stimulation (50 Hz, 80 V, 0.2 ms). Relaxations were blocked by 30 microM N(G)-nitro-L-arginine methyl ester added to the vessel rings. This inhibitory effect was reversed by 3 mM L-arginine. Removal of the vascular endothelium also blocked the relaxation response. Glibenclamide attenuated vasorelaxation in a concentration-dependent manner. We conclude that cochlear nerve stimulation induces an endothelium-dependent vasorelaxation involving activation of adenosine triphosphate-sensitive potassium channels.

Inhibition of myosin light-chain kinase activity in the organ of Corti by 0.3-5 kilodalton substances of the otosclerotic perilymph.

The guinea pig organ of Corti contains myosin light-chain kinase (MLCK) activity. The upper and lower most parts of the cochlea do not show significantly different activities of the enzyme, which is Ca2+ and calmodulin-dependent. Short-term noise exposure does not cause a significant change. 0.3-5 Kilodalton substances of the otosclerotic perilymph, separated by SG-25 column chromatography, inhibit the MLCK activity in in vitro organ of Corti preparations. This inhibitory action of the perilymph substances can also be observed with the purified MLCK of turkey gizzard. The activity of the enzyme can be specifically inhibited by cyclic AMP-dependent protein kinase.

The light-harvesting chlorophyll a/b protein acts as a torque aligning chloroplasts in a magnetic field.

Displacement of particles from the purified light-harvesting chlorophyll a/b protein aggregate (LHC) was studied in magnetic fields of various strengths (0 to 1.6 T) by polarized fluorescence measurements. Macromolecular aggregates of LHC have a considerable magnetic susceptibility which enables the particles to rotate and align with their nematic axes parallel with H. As LHC is embedded in a transmembrane direction thylakoids should align perpendicular to H, the mode of alignment experimentally observed in thylakoids. The value of the magnetic susceptibility could be estimated by relating it to the integral susceptibility of the chlorophyll molecules in LHC. The fitting of this value with the field strength dependency of the fluorescence polarization ratio (FP) revealed a relationship between the LHC content of various photosynthetic membranes and their capacity for alignment, which suggested that LHC might be the torque ordering chloroplasts in a magnetic field.

Energization and ultrastructural pattern of thylakoids formed under periodic illumination followed by continuous light.

Bean leaves grown under periodic illumination (56 cycles of 2 min light and 98 min darkness) were subsequently exposed to continuous illumination, and in connection with granum formation and accumulation of the light-harvesting pigment-protein complex thermoluminescence and light-induced shrinkage of thylakoid membranes were studied. Juvenile chloroplasts with large double sheets of thylakoids obtained under periodic light exhibited low temperature spectra of polarized fluorescence yielding fluorescence polarization (FP) values < 1 at 695 nm, characteristic for pheophytin emission. In the course of maturation under continuous light when normal grana appeared and the chlorophyll a/b light-harvesting photosystem II complex was incorporated into the membrane, at 695 nm the relative intensity of fluorescence dropped and FP changed to a value of > 1, suggesting an overlap between the emission of pheophytin and that of the chlorophyll a/b light-harvesting photosystem II complex. Thermoluminescence glow curves recorded with juvenile thylakoids displayed a relatively high proportion of emission at low temperatures (around -10°C) while with mature chloroplasts, more thermoluminescence originated from energetically deeper traps (discharged around 28°C). This means that during thylakoid development the capacity of the membrane to stabilize the separated charges increases, which might be favourable for the ultimate conservation of energy. The more extensive energization of mature thylakoids was also indicated by a light-induced decrease in the thickness of the membranes upon illumination; a change which could not be detected in juvenile thylakoids.

Cyclic nucleotide and prostaglandin F2 alpha contents of otosclerotic auditory ossicles.

We found that the cyclic-adenosine-3',5'-monophosphate (cAMP) contents of otosclerotic human ossicles were 40-50 times greater than basal levels. Cyclic-guanosine-3',5'-monophosphate (cGMP) levels were also found to be greater than in physiological conditions, but lower than in cortical bone. These findings suggest the extensive participation of these nucleotide coenzymes in effector cells during the process of bone resorption. This emphasizes the role of bone-resorbing cells in this process as well as the probable osteoclast progenitor role of vascular endothelial cells and their enhanced activity for differentiation. At the same time, the absence of prostaglandin F2 alpha content in the otosclerotic bone analyzed appears to exclude cartilage remnants as a source for inducing the changes in remodelling that occur.

Neuromyography in the diagnostics of Bell's palsy.

After summing up the principles and technique of neuromyography, the authors illustrate their clinical application with several cases from their practice. The method is suited for monitoring the degeneration processes in Bell's palsy or other acute peripheral facial nerve pareses. The measurements permit estimating the duration of recovery and the probability of residual signs. The method helps the indication and timing of decompression surgery. In spite of certain difficulties involved in the procedure, its introduction into the diagnostics of facial nerve diseases is recommended.

Cathepsin-B activity in otosclerosis.

Cathepsin-B activity was determined fluorimetrically in the otosclerotic stapes footplate, the stapes superstructure, normal temporal cortical bone, and os frontale osteoma. Measurements with a synthetic substrate made determinations in individual samples possible. The cathepsin-B activity in the otosclerotic stapes footplate was one order of magnitude higher than that of the superstructure, which was not affected by the disease. The cortical bone and the superstructure displayed similar activities, as did os frontale osteoma and otosclerosis. The high lysosomal proteinase activity appears to be closely connected to the otosclerotic bone resorption process.

Orientation of emitting dipoles of chlorophyll A in thylakoids: considerations on the orientation factor in vivo.

Orientation angles of five emitting dipoles of chlorophyll a in thylakoids were estimated from low temperature fluorescence polarization ratio spectra of magnetically oriented chloroplasts. A simple expression is given also for the evaluation of data from linear dichroism measurements. It is shown that the Qy dipoles of chlorophylls lie more in the plane of the membranes and span a larger angular interval than was previously thought. Values for the orientation factor are calculated using various models corresponding to different degrees of local order of the Qy dipoles of chlorophylls in the thylakoid. We show that the characteristic orientation pattern of the Qy dipoles of chlorophylls in the membrane, i.e., increasing dichroism toward longer wavelengths, may favour energy transfer between the antenna chlorophylls as well as funnel the excitation energy into the reaction centers.