John L. Kemink

Independent evaluation of the speech perception abilities of children with the nucleus 22-channel cochlear implant system

The performance of 28 children with the Nucleus multichannel cochlear implant, who had used the device an average of 1.7 yr, was examined on a battery of speech perception measures. All children demonstrated better speech perception skills with the implant than they had in the preimplant condition with hearing aids. With the Nucleus implant, 61% of the children demonstrated some open-set speech recognition and another 14% demonstrated closed-set speech recognition. Scores on the tests were corrected for guessing and a hierarchy of test difficulty was developed. The results revealed systematic differences in performance as a function of perception task and test format. The results of regression analyses, which were performed to identify predictors of success, showed that communication mode made a significant unique contribution to the variance in performance among subjects on an open-set word recognition test. When the scores of the children who used oral or total communication were compared on the full battery of tests, however, there were few significant group differences.

Hearing preservation following suboccipital removal of acoustic neuromas

Advances in the diagnosis and intraoperative management of acoustic neuromas have greatly reduced the incidence of neurologic deficits following their removal. Ninety‐three patients underwent acoustic tumor removal during a 4½‐year period, and hearing preservation was attempted in 20 cases. Hearing was preserved in 65% of the entire series, and excellent results were obtained in tumors less than 1.5 cm. No patient with a tumor greater than 1.5 cm had serviceable hearing preserved when total tumor removal was performed. Two patients, one with neurofibromatosis and one with an acoustic neuroma in an only‐hearing ear, had planned partial tumor removal with preservation of hearing. Preoperative auditory brainstem response results were not predictive of postoperative hearing preservation. Intraoperative auditory brainstem response monitoring demonstrated that loss of wave V consistently correlated with loss of hearing postoperatively, whereas persistence of wave V (with a latency prolongation not exceeding 3.00 ms) was predictive of successful hearing preservation regardless of latency increases.

Total en bloc resection of the temporal bone and carotid artery for malignant tumors of the ear and temporal bone

A technique for single stage total en bloc resection of the temporal bone and infratemporal carotid artery with immediate reconstruction has been described. This formidable procedure requires the collaborative efforts of neurotologic skull base surgeons, neurosurgeons, and head and neck surgeons.

Effects of Preoperative Electrical Stimulability and Historical Factors on Performance with Multichannel Cochlear Implant

We investigated the relationship between results of preoperative transtympanic electrical promontory stimulation, duration of deafness, postoperative implanted psychophysical results, and postoperative speech and speech sound recognition as indicated by a battery of five tests. Our subjects were 10 patients implanted with the Cochlear Corporation multielectrode implant, 1 year postimplantation, with a minimum of 17 active electrodes programmed in the bipolar + 1 mode. The results indicated that preoperative promontory thresholds, the slope of the threshold function, and the duration of auditory deprivation are excellent predictors of postoperative speech and speech sound recognition in the auditory (processor alone) mode. These results have significant implications for patient selection and counseling.

Operative management of acoustic neuromas: The priority of neurologic function over complete resection

The objective of surgical management of acoustic tumors is to remove them entirely and preserve facial nerve function and hearing when possible. A dilemma arises when it is not possible to remove the entire tumor without incurring additional neurologic deficits. Twenty patients who underwent intentional incomplete surgical removal of an acoustic neuroma to avoid further neurologic deficit were retrospectively reviewed. They were divided into a subtotal group (resection of less than 95% of tumor) and a near-total group (resection of 95% or more of tumor) and were followed yearly with either computed tomography or magnetic resonance imaging. The subtotal group was planned and consisted of elderly patients (mean age, 68.5 years) with large tumors (mean, 3.1 cm). The near-total group consisted of younger patients (mean age, 45.8 years) and smaller tumors (mean, 2.3 cm). The mean length of followup for all patients was 5.0 years. Ninety percent of patients had House grade I or II facial function post-operatively. Radiologically detectable tumor regrowth occurred in only one patient, who was in the subtotal resection group. Near-total resection of acoustic tumor was not associated with radiologic evidence of regrowth of tumor for the period of observation. Within the limits of the follow-up period of this study, subtotal resection of acoustic neuroma in elderly patients was not associated with clinically significant recurrence in most patients and produced highly satisfactory rates of facial preservation with low surgical morbidity.

Evaluation of the temporal bones of a multichannel cochlear implant patient.

In this report we detail the temporal bone findings of a 57-year-old patient who underwent placement of a Nucleus 22-channel electrode 7 months prior to his death. Audiometric testing postoperatively demonstrated suprasegmental speech cue discrimination only. Histologic evaluation of the cochleas revealed significant sensorineural survival except in the region of the basal turn of the implanted cochlea adjacent to the implant. There was no significant pathologic condition attributable to the operation or the electrode in areas remote from the basal turn of the cochlea.

Facial Electroneurography: Clinical and Experimental Investigations

Facial electroneurography (ENoG) appears to be a reliable prognostic test for intratemporal facial nerve paralysis. ENoG is objective and allows a permanent record to be maintained. Nonetheless, occasional inconsistencies in clinical correlation may diminish the utility of ENoG. A qualitative study was undertaken to identify the possible reasons for the inaccuracy of ENoG in some patients. Four clinical groups and one experimental group were studied: (1) normal subjects, (2) patients with acute facial palsy, (3) patients with progressive facial palsy, (4) patients with temporal bone tumors and normal facial function, and (5) animals in which one facial nerve was crushed and repaired. The reliability of ENoG is dependent on careful interpretation of data obtained by optimal electrode placement and stimulus duration.

Intraoperative facial nerve monitoring: A comparison of stimulating electrodes

Preservation of the facial nerve during acoustic neuroma resection may be enhanced by the use of intraoperative electrical stimulation. Although stimulation of the extratemporal facial nerve is an effective and established procedure, anatomic differences of the intradural facial nerve and its microenvironment demand more exacting stimulus protocols. The absence of epineurium may make the intradural nerve more susceptible to mechanical or electrical trauma while intermittent pooling of cerebrospinal fluid (CSF) at the cerebellopontine angle may shunt current away from nerve.

Normal auditory brainstem response in patients with acoustic neuroma

Auditory brainstem response testing has been a major breakthrough in audiologic screening for acoustic neuroma because of its high degree of sensitivity. Although it is not uncommon for other cerebellopontine angle masses to present with normal ABR findings, reports of eighth nerve tumors with false‐negative auditory brainstem response tests are quite rare. A series of 120 acoustic neuromas resected at the University of Michigan was reviewed and revealed two such patients. These two patients presented with asymmetric sensorineural hearing loss and unilateral tinnitus and were found to have completely normal auditory brainstem response. The diagnosis of acoustic neuroma would have been delayed if a comprehensive evaluation had not been pursued.

Habituation Therapy for Chronic Vestibular Dysfunction: Preliminary Results:

Chronic vestibular dysfunction is often a frustrating problem for both patient and physician. A program of customized vestibular habituation therapy is introduced and its efficacy in a group of 65 patients is evaluated. Preliminary findings suggest that 59% of patients will have a dramatic improvement, after which their vestibular symptoms no longer cause any restriction in their lifestyles. An additional 23% of patients note considerable improvement, but have persistent symptoms that continue to restrict their activities. Vestibular habituation therapy is a rational, multidisciplinary approach to the treatment of chronic vestibular dysfunction that is a significant alternative to traditional pharmacologic management. Failure of vestibular compensation after involvement in a disciplined program of habituation therapy constitutes a much stronger indication for vestibular surgery in patients with unilateral peripheral lesions.