Biomedical subjects

Jay T Rubinstein

Publications and source records attributed to Jay T Rubinstein.

9 recordsLinked to original sources

PubMed2003

Electrical suppression of tinnitus with high-rate pulse trains.

HYPOTHESIS: Application of high-rate pulse trains (e.g., 4800 pps) to the cochlea may represent an effective treatment of tinnitus. BACKGROUND: Tinnitus is a widespread clinical problem with multiple treatments but no cure. A cure for tinnitus would restore the perception of silence. One plausible hypothesis for the origin of tinnitus associated with sensorineural hearing loss is that it is due to loss or alteration of the normal spontaneous activity in the deafferented regions of the cochlea. Electrical stimulation of the cochlea with 5000-pps pulse trains can produce spontaneous-like patterns of spike activity in the auditory nerve. METHODS: Eleven volunteer human subjects with bothersome tinnitus and high-frequency sensorineural hearing loss underwent myringotomy and temporary placement of a round window electrode. High-rate pulse train stimuli were presented at various stimulus intensities and tinnitus, and stimulus perception were scaled by the subject. Three cochlear implant recipients with tinnitus in the implanted ear underwent similar stimulation. RESULTS: Five of 11 (45%) of transtympanic subjects showed substantial or complete tinnitus suppression with either no perception or only a transient perception of the stimulus. Three showed tinnitus suppression only in association with the perception of the stimulus. Three showed no effects on tinnitus. A similar pattern of responses was seen in the cochlear implant subjects. CONCLUSIONS: Although the study lacked an ideal placebo control, the results are promising and support further research to develop a clinically useful intervention for this troubling disorder.

Adult↗

PubMed2003

Dynamic range enhancement for cochlear implants.

HYPOTHESIS: The addition of a continuous, unmodulated, high-rate pulse train to sinusoidal stimuli presented by the cochlear implant to implant recipients will result in increases in the psychophysical dynamic range. BACKGROUND: The hearing dynamic range of cochlear implant patients is markedly reduced compared with that of normal-hearing individuals. This has negative implications for both speech perception and sound quality in these patients. It has been suggested that the addition of an unmodulated high-rate pulse train to deafened auditory nerves could create spontaneous-like neural activity, similar to that recorded from normal ears, of which one significant benefit would be an increase in the dynamic range of cochlear implant users. METHODS: Twenty-nine patients who underwent implantation with the Clarion CII device participated in this single-blinded prospective study. The psychophysical dynamic range of 28 of these subjects was measured with sinusoidal stimuli in response to various levels of an additional unmodulated high-rate pulse train. RESULTS: All the tested subjects (n = 28) demonstrated an increase in dynamic range in response to an appropriate level of unmodulated high-rate pulse train. The largest increase in dynamic range for each subject had a mean value of 6.7 dB. CONCLUSION: The addition of an unmodulated high-rate pulse train to the electric signal presented to cochlear implant patients results in significant increases in dynamic range for sinusoidal stimuli.

Acoustic Stimulation↗

PubMed2003

Blind deblurring of spiral CT images.

To discriminate fine anatomical features in the inner ear, it has been desirable that spiral computed tomography (CT) may perform beyond their current resolution limits with the aid of digital image processing techniques. In this paper, we develop a blind deblurring approach to enhance image resolution retrospectively without complete knowledge of the underlying point spread function (PSF). An oblique CT image can be approximated as the convolution of an isotropic Gaussian PSF and the actual cross section. Practically, the parameter of the PSF is often unavailable. Hence, estimation of the parameter for the underlying PSF is crucially important for blind image deblurring. Based on the iterative deblurring theory, we formulate an edge-to-noise ratio (ENR) to characterize the image quality change due to deblurring. Our blind deblurring algorithm estimates the parameter of the PSF by maximizing the ENR, and deblurs images. In the phantom studies, the blind deblurring algorithm reduces image blurring by about 24%, according to our blurring residual measure. Also, the blind deblurring algorithm works well in patient studies. After fully automatic blind deblurring, the conspicuity of the submillimeter features of the cochlea is substantially improved.

Algorithms↗

PubMed2003

Neuroepithelial cysts of the middle ear.

Neuroepithelial cysts are lesions of the central nervous system that have previously been reported in cerebral parenchyma, in the spinal cord, and within the ventricles in association with the choroid plexus. We describe 2 cases of neuroepithelial cysts of the middle ear. One was diagnosed after surgery for a retraction pocket and chronic otitis media complicated by an intraoperative cerebrospinal fluid (CSF) leak. The other produced bilateral spontaneous CSF otorrhea and mimicked the presentation of arachnoid granulations. Both cases were verified with immunohistochemical stains. Neuroepithelial cysts, although rare, should be considered in the differential diagnosis of spontaneous CSF otorrhea or an epitympanic mass.

Aged↗

PubMed2002

Paediatric cochlear implantation: prosthetic hearing and language development.

CONTEXT: Cochlear implantation offers hearing and vocational benefits to children and adults who lose their hearing after acquiring speech and language. But such implantations in prelingually deaf children are controversial, with concerns about diagnosis in very young children, safety, and durability. Implantation of children under age 2 years is potentially associated with higher surgical and anaesthesia risks, and with more challenging preoperative and postoperative management. STARTING POINT: Although only a small number of children implanted before age 2 have sufficient maturity and implant experience to undergo adult-type speech recognition tests, surgical series show that these children may be implanted safely and that their subsequent speech perception is at least as good as children implanted at an older age. The Nottingham, UK, group recently reported on a consecutive sample of 12 children aged under 2 years at implantation (Arch Otolaryngol Head Neck Surg 2002; 128: 11-14). S S Hehar and colleagues show satisfactory perioperative and postoperative surgical outcomes. 2 years after the implantation, mean scores on the Listening Progress Profile had increased from 1 to 42. Median scores of Categories of Auditory Performance increased from 0 to 5. There were no significant differences compared with a historical control group of deaf children implanted at ages 3-5. WHERE NEXT? Early results from parental observation of auditory behaviours show that children who receive a cochlear implant at an early age perform at least as well as those implanted later. These data, combined with more rigorous speech recognition results in older children, merit a gradual reduction in the age of implantation, although the uncertainties inherent in audiometric assessment and measurement of hearing-aid benefit in infants must be borne in mind. Cochlear implants in prelingually deafened children permit improved development of speech reception, language acquisition, and reading comprehension.

Child↗

PubMed2002

Three-month results with bilateral cochlear implants.

OBJECTIVES: To evaluate possible binaural listening advantages for speech in quiet, speech in noise, and for localization in a group of postlingually deafened adults with two cochlear implants functioning independently after 3 mo experience. DESIGN: Nine postlingually deafened subjects who had received a Cochlear Corporation CI24M implant in each ear were evaluated on a number of tasks. The subjects all had audiometric or biographical (e.g., duration of deafness) differences between the ears. Word and sentence materials were presented to the subjects in quiet and in noise with the signal always in the front and the noise from the front or either side. Results are reported for each ear and for both ears with the noise on either side. This allowed evaluation of head shadow and squelch effects. Additionally, localization ability was assessed for broadband noise presented either to the right or left of center at 45 degrees azimuth. Localization was assessed for each ear and for both ears. RESULTS: Results of speech testing in quiet showed a significant advantage for the binaural condition over the better ear in four subjects. In noise, with both signal and noise in front of the subject, a significant advantage of two ears over the better ear was found for four subjects. For noise to one side of the head, when the ear opposite the noise source was added to the ear ipsilateral to the noise, a significant advantage was demonstrated for seven of seven tested subjects. When the ear ipsilateral to the noise was added to the ear contralateral to the noise, a significant advantage was shown for only one of seven (noise on right) and three of seven (noise on left) tested subjects. The localization task showed that all seven tested subjects could discriminate 45 degrees left from 45 degrees right above chance with bilateral stimulation. Three subjects could perform the discrimination above chance with only one ear. However, performance with both ears was significantly better than performance with one ear for two of these latter subjects. CONCLUSIONS: We conclude that bilateral cochlear implants can provide real advantages, particularly when it is possible to utilize the ear that is away from a noise source, thus taking advantage of the head shadow effect. In addition, localization ability was generally better with two implants than with one.

Acoustic Stimulation↗

PubMed2002

Binaural cochlear implants placed during the same operation.

OBJECTIVE: To evaluate the binaural listening advantages for speech in quiet and in noise and to localize sound when independently programmed binaural cochlear implants are used, and to determine whether ears with different hearing ability and duration of profound deafness perform differently with cochlear implants as well as to what extent preimplant psychophysical and physiologic assessment could be predictive of performance. STUDY DESIGN: Prospective study in which patients were prospectively selected to undergo bilateral implantation during a single surgical procedure at a tertiary referral center. All testing was performed with patients using their right, left, or both cochlear implants. Preimplant and intraoperative measures used electrical stimulation at the round window and stimulation through the cochlear implant. RESULTS: Bilateral implantation during the same operation did not cause any postoperative problems such as severe vertigo or ataxia. At 1 year, results of speech testing in quiet demonstrated a binaural advantage for 2 of 10 subjects. Speech-in-noise testing demonstrated that two implants were beneficial for two individuals. All subjects benefited from a head shadow effect when an ear with a better signal-to-noise ratio was available. The ability to localize sound was improved with binaural implants in all subjects. Preimplant psychophysical or physiologic measures were not predictive of eventual speech perception performance. CONCLUSION: Binaural cochlear implants can assist in the localization of sounds and have the potential in some individuals to improve speech understanding in quiet and in noise.

Adult↗

PubMed2002

Comparison of algorithms for the simulation of action potentials with stochastic sodium channels.

This paper presents a comparison of computational algorithms to simulate action potentials using stochastic sodium channels. Four algorithms are compared in single-node models: Strassberg and DeFelice (1993) (SD), Rubinstein (1995) (R), Chow and White (1996) (CW), and Fox (1997) (F). Neural responses are simulated to a simple and a preconditioned monophasic current pulse. Three exact algorithms implementing Markov jumping processes (SD, R, CW) resulted in similar responses, while the approximation algorithm using Langevin's equation (F) showed quite different responses from those in the exact algorithms. The computational time was measured as well: 1(F), 7(CW), 32(SD), 39(R) relative to that of the F algorithm. Furthermore, it is shown that as the sampling step for integration of the transmembrane potential increases, neural responses in all algorithms tended to be different from those in dense sampling steps, however, the CW algorithm was robust even at a sparse sampling step. It is concluded that the most computationally efficient algorithm having appropriate properties of neural excitability is the CW algorithm.

Action Potentials↗

PubMed2002

Blind deblurring of spiral CT images-comparative studies on edge-to-noise ratios.

A recently developed blind deblurring algorithm based on the edge-to-noise ratio has been applied to improve the quality of spiral CT images. Since the discrepancy measure used to quantify the edge and noise effects is not symmetric, there are several ways to formulate the edge-to-noise ratio. This article is to investigate the performance of those ratios with phantom and patient data. In the phantom study, it is shown that all the ratios share similar properties, validating the blind deblurring algorithm. The image fidelity improvement varies from 29% to 33% for different ratios, according to the root mean square error (RMSE) criterion; the optimal iteration number determined for each ratio varies from 25 to 35. Those ratios that are associated with most satisfactory performance are singled out for the image fidelity improvement of about 33% in the numerical simulation. After automatic blind deblurring with the selected ratios, the spatial resolution of CT is substantially refined in all the cases tested.

Algorithms↗