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Biomedical subjects

N L Cohen

Publications and source records attributed to N L Cohen.

At least 19 recordsLinked to original sources
PubMed1996

Systematic approach to electrode insertion in the ossified cochlea.

Ossification of the fluid spaces of the cochlea occurs often in candidates for cochlear implantation, especially children. When noted before surgery on computerized tomography, ossification previously was thought to contraindicate cochlear implantation because of possible mechanical obstruction and uncertainty about the level of function that could be achieved by stimulating an ossified cochlea. However, during the preceding 6 years, techniques have been developed that permit implantation in ossified cochleas. We present a systematic approach that has been developed to treat the three clinically important categories of cochlear ossification: round window niche obliteration, inferior segment obstruction, and upper segment obstruction. Case reports are presented for each of these three drill-out procedures, demonstrating results often similar to those expected for implantation of the nonossified cochlea.

Adult↗
PubMed1995

Retrofacial approach to the hypotympanum.

Otologic disease often extends into the hypotympanum, posterior mesotympanum, and infralabyrinthine compartments. Surgical access to these areas can be difficult because of the proximity of the facial nerve. In patients with a normal bone anatomy, these regions can be accessed by a retrofacial approach, which spares the posterior canal wall and avoids transposition of the facial nerve. The anatomy of the hypotympanum, posterior mesotympanum, and infralabyrinthine compartments will be reviewed emphasizing gross anatomic documentation. We will detail the surgical approach to these areas along the retrofacial air cell tract, and will present an appropriate case history.

Ear Neoplasms↗
PubMed1995

Postoperative imaging of the multichannel cochlear implant.

PURPOSE: To present the postoperative radiographic appearance of the multichannel cochlear implant and to suggest criteria for the radiographic evaluation of postimplant patients. METHODS: One hundred forty-one patients, 73 female and 68 male, had multichannel cochlear implants inserted. One hundred thirty-five intraoperative radiographs, 31 postoperative radiographic examinations, and 10 postoperative CT examinations were retrospectively reviewed. RESULTS: In 135 patients, a Stenver's or anteroposterior projection confirmed the normal placement of the implant by demonstrating the electrodes to be regularly spaced and gently curved within the first turn of the cochlea. The insertion depth was determined by counting the number of electrodes that projected medial to the cochlear promontory. In 5 patients in whom intracochlear placement of the electrode array could not be confirmed on plain radiographs, CT demonstrated the location of the electrode array. In 3 patients with postoperative infections, CT either correctly identified or excluded the presence of a collection beneath the implant. CONCLUSION: Plain radiographs of the temporal bone are sufficient for the postoperative treatment of the majority of postimplant patients. CT should be performed when plain radiographs cannot adequately show the location of the electrode array or if postoperative infection is suspected.

Adolescent↗
PubMed1995

Predictors of postoperative performance with cochlear implants.

One objective of the Department of Veterans Affairs study: A Prospective Randomized Study of Advanced Cochlear Implants was to attempt to identify preoperative patient characteristics that might predict postoperative performance. We studied the relationship between all preoperative factors and the 2-year postoperative performance on 24 audiological tests for 82 patients who were implanted with the Ineraid, Nucleus, or 3M/Vienna device. Results of the univariate analysis indicated that computed tomographic findings of the cochlea and round window, IQ, age at implantation, length of deafness, profound deafness, and lipreading ability weakly correlated to postoperative performance. The multivariate analysis showed age at time of implantation, IQ, and lipreading ability to be predictive of postoperative performance.

Age of Onset↗
PubMed1995

Influence of processing strategies on cochlear implant performance.

The development of new processing strategies has allowed for the improvement of auditory skills in cochlear implant recipients. This study examines the effects of a change in processing strategy on the individual recipients of the Nucleus cochlear prosthesis. Twenty-five subjects who had used the F0F1F2 processing strategy (WSP III) for 2 years were switched to the MPeak strategy (MSP) and retested immediately and after 3 months. Results revealed an improvement in speech recognition ability with the MPeak strategy in those subjects who were able to perceive speech with the F0F1F2 processing strategy.

Cochlea↗
PubMed1995

Efficacy of auditory brainstem response as a screening test for small acoustic neuromas.

Auditory brainstem response (ABR) has been advocated as a high sensitivity screening test for acoustic neuroma. With the advent of magnetic resonance imaging (MRI), smaller size acoustic neuromas are now detectable. A prospective trial was performed to determine the sensitivity of ABR in diagnosing small acoustic neuromas. One hundred five randomly selected patients with surgically proved acoustic neuromas underwent preoperative ABR tests within 2 months of their surgery. Patients with a histologic diagnosis other than acoustic neuroma were excluded from this study. A test was considered abnormal when the interaural wave I-V latency difference was greater than 0.2 ms, the absolute wave V latency was abnormally prolonged, or there was abnormal or absent waveform morphology. Of the 105 patients tested 92 (87.6%) had abnormal ABR test, and 13 (12.4%) had completely normal waveforms and wave latencies. Eighteen patients had tumors over 2 cm in total diameter. Of these, 12 were 2.5 cm or larger and 6 were between 2.1 and 2.4 cm. All of these 18 patients had abnormal ABR tests. Of the 29 patients with tumors 1.6-2.0 cm in size, 25 (86%) had abnormal ABRs. In the 1.0-1.5 cm diameter range there were 45 patients who underwent a preoperative ABR. Of these, 40 (89%) had abnormal ABRs. Of 13 patients with tumors 9 mm or smaller, only 9 (69%) had abnormal ABR test (p < .05). Thus, it appears that ABR sensitivity decreases with tumor size and is particularly inadequate for tumors of less than 1 cm in diameter. The authors conclude that ABR is not a good screening test for smaller acoustic neuromas and recommend MRI for patients with suspected acoustic neuroma.

Contrast Media↗
PubMed1995

Autologous fibrin glue in the prevention of cerebrospinal fluid leak following acoustic neuroma surgery.

Postoperative cerebrospinal fluid (CSF) leak is a serious complication of acoustic neuroma surgery. The authors retrospectively reviewed the charts of 492 patients who underwent acoustic neuroma surgery to determine the efficacy of fibrin glue in preventing postoperative CSF leak. Thirteen of 92 patients (14%) undergoing retrosigmoid/transmeatal surgery experienced CSF leak when fibrin glue was used; 29 of 199 patients (15%) when it was not used. Nineteen of 85 patients (22%) experienced CSF leak when fibrin glue was used following translabyrinthine surgery; 23 of 116 patients (20%) when it was not used. No decrease was noted in the incidence of CSF leak following acoustic neuroma surgery with the use of autologous fibrin glue.

Cerebrospinal Fluid Otorrhea↗
PubMed1994

Long-term results of early cochlear implantation in congenitally and prelingually deafened children.

Cochlear implants have been shown to improve the speech perception and production skills in children. Data are available on congenitally and prelingually deafened children who were implanted at an older age, but data on children implanted below the age of 3 years are scarce. The present study examines the benefits obtained with early implantation of the young deaf child. Fourteen congenitally or prelingually profoundly hearing-impaired children were implanted before the age of 3 years, with the Nucleus multichannel cochlear prosthesis, and followed for 2-5 years. Results indicate an overall improvement in the perception of all aspects of the speech signal in the auditory-only condition with the cochlear implant. All the children use oral language as their primary mode of communication and attend regular schools. Based on the results of this investigation, the authors conclude that implantation of the young deaf child is beneficial to the development of auditory perceptual skills.

Age of Onset↗
PubMed1993

A prospective, randomized study of cochlear implants. The Department of Veterans Affairs Cochlear Implant Study Group.

BACKGROUND: Cochlear implants restore some degree of hearing in patients with severe hearing impairment, but the efficacy of different implants has not been compared. We conducted a prospective trial to compare several cochlear implants. METHODS: We studied 82 patients who were randomly assigned to receive one of three cochlear implants: the Ineraid multichannel implant (implant 1), the Nucleus multichannel implant (implant 2), and the 3M/Vienna single-channel implant (implant 3). All the patients had profound deafness, and none had derived benefit from hearing aids. The assigned device was successfully implanted in 80 patients. Twenty-four hearing tests were used to assess the patients' performance before implantation and 12 and 24 months after implantation. The tests were grouped into five categories according to their content, and a weighted composite index was developed to provide a single numerical indicator of the overall auditory response. RESULTS: All the patients were able to hear with their implants. Nineteen of the 30 patients (63 percent) who received implant 2, 18 of the 30 patients (60 percent) who received implant 1, and 1 of the 20 patients (5 percent) who received implant 3 were able to distinguish some words and sentences. The scores for the composite index were similar in the patients who received implant 1 and those who received implant 2, and were higher in both these groups than in the patients who received implant 3 (P = 0.02). When 24 patients with implant 2 were given an improved speech processor, their composite index increased significantly within 3 months (P < 0.001); their score at that time was also significantly higher (P = 0.04) than the score of the patients with implant 1 at 24 months. Age at implantation, lip-reading ability, and IQ were prognostic indicators of the patients' performance with a cochlear implant. CONCLUSIONS: Multichannel cochlear implants are superior to single-channel implants, especially for understanding speech. Changes in speech processing can improve patients' performance.

Aged↗