Is There Any Correlation between Spread of Excitation Width and the Refractory Properties of the Auditory Nerve in Cochlear Implant Users?

BACKGROUND

The spread of excitation (SOE) and auditory nerve recovery function (REC) are objective measures recorded by neural response telemetry and may interfere in cochlear implant (CI) stimulation.

OBJECTIVE

To analyze and correlate SOE with the refractory periods in subjects with pre- and postlingual deafness implanted with different electrode arrays.

METHODS

This was a retrospective study of 323 ears separated by perimodiolar or straight arrays and by pre- or postlingually deaf recipients. Measures were collected intraoperatively on electrode 11. The SOE width was measured in millimeters at the 0.75 point of the curve, and the relative (tau) and absolute (t0) refractory periods were measured in microseconds.

RESULTS

There was a statistical correlation between the SOE and the t0 in the patients with postlingual deafness implanted with the perimodiolar array. The SOE width was statistically different between the straight and perimodiolar arrays and between the pre- and postlingual groups in the perimodiolar array. Tau was statistically different between the pre- and postlingual groups with the straight array and the t0, between the pre- and postlingual groups with the perimodiolar array. Neural response threshold and amplitude of the neural response were not statistically different among groups.

CONCLUSION

There was a correlation between SOE width and t0 only in patients with acquired deafness. The findings suggest that different factors influence SOE and REC, considering SOE is different according to the electrode array and REC being different according the onset of deafness.

Auditory brainstem implant outcomes and MAP parameters: report of experiences in adults and children

The auditory brainstem implant (ABI) was first developed to help neurofibromatosis type 2 patients. Recently, its use has been recently extended to adults with non-tumor etiologies and children with profound hearing loss who were not candidates for a cochlear implant (CI). Although the results has been extensively reported, the stimulation parameters involved behind the outcomes have received less attention.

OBJECTIVE

The aim of this study is to describe the audiologic outcomes and the MAP parameters in ABI adults and children at our center.

METHODS

Retrospective chart review. Five adults and four children were implanted with the ABI24M from September 2005 to June 2009. In the adult patients, four had Neurofibromatosis type 2, and one had postmeningitic deafness with complete ossification of both cochleae. Three of the children had cochlear malformation or dysplasia, and one had complete ossified cochlea due to meningitis. Map parameters as well as the intraoperative electrical auditory brainstem responses were collected. Evaluation was performed with at least six months of device use and included free-field hearing thresholds, speech perception tests in the adult patients and for the children, the Infant-Toddler Meaningful Auditory Integration Scale (IT-MAIS) and (ESP) were used to evaluate the development of auditory skills, besides the MUSS to evaluate.

RESULTS

The number of active electrodes that did not cause any non-auditory sensation varied from three to nineteen. All of them were programmed with SPEAK strategy, and the pulse widths varied from 100 to 300 μs. Free-field thresholds with warble tones varied from very soft auditory sensation of 70 dBHL at 250 Hz to a pure tone average of 45 dBHL. Speech perception varied from none to 60% open-set recognition of sentences in silence in the adult population and from no auditory sensation at all to a slight improvement in the IT-MAIS/MAIS scores.

CONCLUSION

We observed that ABI may be a good option for offering some hearing attention to both adults and children. In children, the results might not be enough to ensure oral language development. Programming the speech processor in children demands higher care to the audiologist.

Resultados audiológicos do implante coclear em idosos

According to data from the Brazilian Institute of Geography and Statistics, the elderly population grew 47.8% in the last decade in Brazil. A portion of this population has severe and/or profound hearing loss and do not benefit from conventional hearing aids. Thus, the use of cochlear implant is required.

Aim

To analyze the benefits of cochlear implants in the elderly based on the comparison of primary auditory thresholds before and after the operation, discrimination of sentences in speech and in talking on the telephone.

Methodology

Retrospective cohort study, analyzing medical records from patients aged over 60 years, users of cochlear implant for at least 1 year.

Results

Fourteen medical records were analyzed. Mean age of patients was 63.07 years. The mean pure tone thresholds between 500Hz, 1kHz, 2kHz and 4kHz before the implantation was 113dBHL. None of the patients, before operation, could discriminate sentences in open sets and only 3 scored 17% in closed sets sentence recognition. After one year of implantation, the mean sound field thresholds reached 34dBHL, and open set sentences recognition of 93.57%, while 71% of the patients had become able to have a conversation on the telephone.

Conclusion

The elderly users of cochlear implant showed important outcomes, with significant improvement in understanding in the open set and in using the telephone.

Neural response thresholds in the Nucleus Contour cochlear implant before and after stylet removal

CONCLUSION

The study shows that there are differences in the measurement of the action potentials with and without the stylet in the Nucleus Freedom Contour Advance that are higher in the apex than in the base of the cochlea.

OBJECTIVES

To determine if there are differences in the intraoperative impedances and in the neural response telemetry threshold values in the Nucleus Freedom Contour Advance before and after stylet removal.

SUBJECTS AND METHODS

This was a prospective clinical study. Intraoperative impedances and neural response telemetry in users of the Freedom Contour Advance Cochlear Implant were measured before and after stylet removal.

RESULTS

There was a significant reduction in the impedance values of an average 1.5 kOmega+/-2.3 in common ground mode and 1.3 kOmega+/-2.3 for all monopolar modes after the stylet removal (p < 0.001). When analyzing the apical, medium, and basal electrodes, there was a statistically significant reduction in the neural response thresholds after stylet removal only in the apical electrodes (p = 0.001).

T cell-monocyte contact enhances tumor necrosis factor-alpha production in response to Mycobacterium leprae

Tumor necrosis factor (TNF)-alpha has been implicated as a key factor in inflammatory processes occurring in erythema nodosum leprosum (ENL). In the present study, the roles of soluble factors and contact-mediated interaction in the induction of enhanced TNF-alpha secretion in leprosy have been investigated. In vitro studies have demonstrated that Mycobacterium leprae per se is a poor stimulus for TNF-alpha production by purified monocytes obtained from normal subjects, although this could be enhanced by either exogenous interferon-gamma or cell contact with fixed activated T lymphocytes. Further investigations demonstrated that monocyte-T cell contact enhanced M. leprae-induced TNF-alpha production by peripheral blood mononuclear cells of ENL patients and was modulated by blocking antibodies to CD40L, CD69, and CD18. These results suggest that physical contact with T cells isolated from patients in a particular disease state (ENL) modulates monocyte function and may contribute to the secretion of proinflammatory cytokines described in ENL.