ABSTRACT: Although it is clear that early auditory stimulation through cochlear implantation (CI) has been shown to improve speech and language development trajectories for children with prelingual hearing loss, data supporting implantation in postlingual children are mostly lacking. The purpose of this study was to characterize speech perception abilities following CI in a group of children with previously well-developed language abilities.
Twenty-eight hearing-impaired children who received CIs were selected for study based on the presence of well-developed spoken language skills before implantation. Fifteen children with prelingual hearing loss served as a control group. Speech perception skills were assessed using developmentally appropriate measures.
Children with postlingual hearing loss showed a statistically significant improvement in open-set speech perception scores as early as 6 months following CI, whereas prelingual children demonstrated significant improvements only after 24 months of use. Despite these early disparities in performance, the two groups were similar 36 months after implantation and beyond (60 months of implant use).
Children with well-developed language abilities before CI showed substantial (and statistically significant) early improvements in open-set speech perception abilities following implantation that continued beyond 2 years of follow-up. These results suggest that postlingual children are excellent candidates for CI.
The Laryngoscope 05/2012; 122(8):1852-7. · 1.75 Impact Factor
ABSTRACT: An intraoperative monitoring algorithm during cochlear implant electrode insertion could be used to detect trauma and guide electrode placement relative to surviving hair cells. The aim of this report was to assess the feasibility of using extracochlear recording sites to monitor acoustically evoked responses from surviving hair cells and neural elements during implantation in an animal model.
The normal-hearing gerbil was used. Two recording methods, one using a lock-in amplifier and another using Fourier analysis of recorded signals, were used to obtain frequency-specific information about the responses to tones. Amplitude and threshold determinations were made at the round window and at three extracochlear sites. To induce intracochlear damage, a platinum-iridium wire was inserted through the round window. The wire was advanced, and changes in the potentials were correlated with cochlear contact. Anatomic integrity was assessed using cochlea whole mount preparations.
In general, the lock-in amplifier showed greater sensitivity and lower thresholds at higher frequencies relative to the Fourier method. Also, the lock-in amplifier was more resistant to masking effects. Both systems were able to detect loss of cochlear potentials secondary to intracochlear trauma. Histologic damage was seen in all cases and corresponded to electrophysiologic changes.
Impact of electrodes on cochlear structures affecting cochlear performance could be detected from several extracochlear sites. The lock-in amplifier demonstrated greater sensitivity and resistance to noise when compared to the fast Fourier transform recording paradigm. The latter showed greater flexibility of detecting and separating hair cell and neural potentials.
The Laryngoscope 03/2012; 122(3):636-44. · 1.75 Impact Factor
ABSTRACT: Cochlear trauma due to electrode insertion can be detected in acoustic responses to low frequencies in an animal model with a hearing condition similar to patients using electroacoustic stimulation.
Clinical evidence suggests that intracochlear damage during cochlear implantation negatively affects residual hearing. Recently, we demonstrated the usefulness of acoustically evoked potentials to detect cochlear trauma in normal-hearing gerbils. Here, gerbils with noise-induced hearing loss were used to investigate the effects of remote trauma on residual hearing.
Gerbils underwent high-pass (4-kHz cutoff) noise exposure to produce sloping hearing loss. After 1 month of recovery, each animal's hearing loss was determined from auditory brainstem responses and baseline intracochlear recording of the cochlear microphonic and compound action potential (CAP) obtained at the round window. Subsequently, electrode insertions were performed to produce basal trauma, whereas the acoustically generated potentials to a 1-kHz tone-burst were recorded after each step of electrode advancement. Hair cell counts were made to characterize the noise damage, and cochlear whole mounts were used to identify cochlear trauma due to the electrode.
The noise exposure paradigm produced a pattern of hair cell, auditory brainstem response, and intracochlear potential losses that closely mimicked that of electrical and acoustic stimulation patients. Trauma in the basal turn, in the 15- to 30-kHz portion of the deafened region, remote from preserved hair cells, induced a decline in intracochlear acoustic responses to the hearing preserved frequency of 1 kHz.
The results indicate that a recording algorithm based on physiological markers to low-frequency acoustic stimuli can identify cochlear trauma during implantation. Future work will focus on translating these results for use with current cochlear implant technology in humans.
Otology & neurotology: official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology 10/2011; 32(8):1370-8. · 1.44 Impact Factor