Regenerative proliferation in inner ear sensory epithelia from adult guinea pigs and humans.

Supporting cells in the vestibular sensory epithelia from the ears of mature guinea pigs and adult humans proliferate in vitro after treatments with aminoglycoside antibiotics that cause sensory hair cells to die. After 4 weeks in culture, the epithelia contained new cells with some characteristics of immature hair cells. These findings are in contrast to expectations based on previous studies, which had suggested that hair cell loss is irreversible in mammals. The loss of hair cells is responsible for hearing and balance deficits that affect millions of people.

Effect of exercise on perfusion of collateral-dependent myocardium in dogs with chronic coronary artery occlusion.

Since the ability of mature intercoronary collateral channels to increase myocardial blood flow in response to drug-induced coronary vasodilation has been questioned, the present study was undertaken to evaluate the response of coronary collateral circulation to the stress of exercise. Studies were performed at rest and during two levels of treadmill exercise in six dogs a minimum of 6 mo after placement of an Ameroid constrictor on the left circumflex coronary artery. Regional myocardial blood flow was estimated in normally perfused anterior and predominantly collateral-dependent posterior left ventricular wall with left atrial injections of radio-nuclide-labeled microscheres 7-10 mum in diameter. At rest, heart rate was 87 +/- 7 beats/min and mean myocardial blood flow was comparable in control and collateral-dependent regions (0.96 +/- 0.13 and 0.97 +/- 0.14 ml/min-g, respectively). During exercise, heart rates increased to 180 +/- 13 and 228 +/- 14 beats/min and myocardial blood flow (MBF) in the anterior control region increased linearly with heart rate (HR), (MBF = 0.133 HR - 0.202, r = 0.88). MBF to the posterior collateral-dependent region was similarly augmented during exercise (MBF = 0.140 HR - 0.252, r = 0.89), so that the linear correlation between HR and MBF was similar for the control and collateral-dependent regions. In addition, the transmural distribution of MBF was uniform at rest and during exercise in both the anterior control and posterior collateral-dependent regions. Thus, not only could the mature intercoronary collateral vasculature supply adequate flow at rest, but when subjected to the natural stress of exercise, the increase in flow to the predominantly collateral-dependent area was similar to that in the normally perfused area.

Recovery of noise-induced changes in the dark cells of the quail tegmentum vasculosum.

Morphologic changes in the tegmentum vasculosum (TV) of adult quail after high intensity sound exposure were studied. Quail were continuously exposed to 115 dB SPL, 1500 Hz pure tone in a sound field for 12 h and either sacrificed immediately (0 day), 1, 2, 3, 4, 6 or 10 days later. Serial sections through the basilar papilla at 100 micron intervals from base to apex were obtained for study with light microscopy and TEM. Significant morphologic changes were found within the TV of quail sacrificed on days 0-4. On a quantitative scale, the majority of recovery occurred within the first 24 h. After four days survival the tegmentum appeared nearly normal. This recovery correlates well with the temporal pattern of threshold shift recovery. These results demonstrate a temporal correlation between ultrastructural changes in the TV and functional recovery of hearing after intense sound exposure. A potential etiologic role of the TV in avian temporary threshold shift is suggested.

Inner ear hair cell regeneration in a mammal: identification of a triggering factor.

Recent observations have shown that mammals possess a limited capacity for regeneration of inner ear sensory epithelia. It is clear, however, that a mitogenic growth factor will be necessary to up-regulate this capacity before clinical application becomes feasible. This study used in vitro cultures of adult mouse vestibular organs for assessing the mitogenic effect of transforming growth factor alpha (TGF-alpha). Sixty-one utricles and cristae were maintained in culture for 7 to 8 days. Neomycin was used to damage the hair cells. Autoradiography permitted identification of any cell which had undergone mitosis during the culture period. The proliferative response was compared in organs exposed to TGF-alpha and those maintained in the basic culture medium only. The results demonstrated that TGF-alpha significantly increased cell proliferation in the sensory epithelia and also in the marginal zones surrounding them. This finding provides a scientific basis for the concept that inner ear hair cell damage in humans may someday be reversible pharmacologically.

Congenital absence of the oval window.

From 1983 to 1987, seven patients with conductive hearing loss were found to have congenital absence of the oval window. Six of these patients underwent vestibulotomies and reconstruction with House wires or total ossicular reconstruction prostheses. Surgical findings included absent or rudimentary stapes in all cases, abnormal facial nerves in four cases, and abnormal long processes of the incus in four cases. All patients had normal external ear canals and tympanic membranes. Hearing initially improved 20 to 45 dB in four of the six patients reconstructed. Over time, however, much of this initial hearing gain was lost. A marked difference in hearing results was evident between this series of absent oval window cases and a recent series of major atresia cases.

Congenital aural atresia: stability of surgical results.

OBJECTIVES/HYPOTHESIS: To compare early (<1 y) and longer-term (1.0-7.5 y; mean follow-up, 2.8 y) hearing results following surgery for congenital aural atresia and to analyze revision cases for cause of failure, time of occurrence, and outcome. STUDY DESIGN: Retrospective study of 55 consecutive patients (59 ears) undergoing surgery during an 11-year period for congenital aural atresia. METHODS: The best speech reception threshold (SRT) during the first postoperative year was compared with the most recent SRT beyond the first postoperative year. The complication rate and long-term hearing results (>1 y) for initial and revision surgeries were compared. RESULTS: In the early postoperative period, an SRT of < or =25 dB was achieved in 60% and an SRT of < or =30 dB in 70%. With longer follow-up (mean, 2.8 y), 46% of patients maintained an SRT < or =25 dB. Revision surgery was necessary in approximately one third of patients. Longer-term hearing results following initial surgery only or after revision surgery showed an SRT < or =25 dB in 53% and an SRT < or =30 dB in 64%. For primary and revisions surgeries the incidence of temporary facial paralysis was 1.5% and for significant hearing loss, 3.0%. CONCLUSIONS: Some degradation in hearing does occur as patients are followed beyond the first postoperative year. Revision surgery will be necessary in approximately one third of cases. With revisions, an SRT < or =25 dB can be expected in half of cases and an SRT < or =30 dB in two thirds of cases. The ability to provide these hearing results supports this surgery in unilateral cases.

Delayed vertigo and profound sensorineural hearing loss.

Episodic vertigo, similar to that of Meniere's disease, can occasionally develop years to decades after an ear has suffered a profound sensorineural hearing loss. Although the pathogenesis of this process is unknown, it is theorized that delayed endolymphatic hydrops develops. An inflammatory reaction could cause obstruction of the endolymphatic duct or interfere with venous drainage from the region of the endolymphatic sac, leading to hydrops. This condition is reviewed, and two adult patients with severe episodic vertigo and a unilateral profound sensorineural hearing loss which occurred in childhood are presented. Their evaluation and management are discussed.

Facial paralysis in longitudinal temporal bone fractures: a review of 26 cases.

The management of facial nerve injury resulting from temporal bone fracture continues to be a topic of discussion. The indications for surgery as well as the proper timing and extent of surgical exploration are the principal questions debated. This study reviews a large series of patients (26), treated for facial paralysis following a longitudinal temporal bone fracture. The most frequent site of injury was the area of the geniculate ganglion. The injury to the facial nerve was often severe. We recommend early exploration in these cases when electrical studies indicate a severe injury. In most cases a combined mastoid and middle fossa approach is required.

Hearing results after primary cartilage tympanoplasty.

OBJECTIVES/HYPOTHESIS: Cartilage-perichondrium grafting of the tympanic membrane has been used in an effort to reduce recurrence or progression of middle ear disease. The rigidity of cartilage has obvious benefit in preventing tympanic membrane retraction, but concern has been raised regarding its sound conduction properties Few studies in the literature address hearing results after cartilage tympanoplasty. The purpose of this study was to investigate the hearing results after primary cartilage tympanoplasty and compare them with results after primary tympanoplasty with temporalis fascia. STUDY DESIGN: A retrospective review of all ear surgeries using cartilage between 1994 and 1999 was performed. METHODS: Only primary cases in which the ossicular chain was intact and no mastoid surgery was performed were included. Indications for surgery included tympanic membrane perforation, retraction, and cholesteatoma Pre- and postoperative speech reception thresholds and air-bone gaps at 500 Hz, 1,000 Hz, 2,000 Hz, and 4,000 Hz were compared. RESULTS: Eleven patients comprised the cartilage study group, and there were 11 age- and temporally matched control subjects. The mean improvement in speech reception threshold for both the study group and the control group was 10 dB. The majority of patients in both groups had ABG closure to within 10 dB at all frequencies examined. There were no statistically significant differences in speech reception threshold improvement or air-bone gap closures between the two groups. CONCLUSIONS: These results demonstrate that hearing results after cartilage tympanoplasty are comparable to those after temporalis fascia tympanoplasty. Therefore, when indicated, a cartilage-perichondrium graft can be used for prevention of disease recurrence or progression without fear of impairing hearing.

Promontory electrical stimulation in postoperative acoustic tumor patients.

Complete deafness can follow acoustic tumor surgery and results from labyrinthine injury, auditory nerve trauma, and/or vascular compromise. A central auditory prosthesis is one potential rehabilitative strategy in such patients. Anatomical studies suggest that some spiral ganglion cells may survive after vascular occlusion, and we have demonstrated responses to electrical stimulation in patients after labyrinthectomy. It was thus hypothesized that patients deafened after a hearing conservation attempt, but maintaining an intact auditory nerve, could utilize an intracochlear implant. To investigate this possibility, promontory electrical stimulation was performed on three patients who had tumors less than 2 cm and who had serviceable preoperative hearing, but no responses postoperatively. Behavioral responses and electrically evoked auditory brainstem and middle latency responses were obtained from two patients, one of whom was 6 years postsurgery. These data indicate that a cochlear implant may be possible after acoustic tumor surgery.

Multichannel cochlear implant and electrically evoked auditory brainstem responses in a child with labyrinthitis ossificans.

Ossification of the cochlea following meningitis presents a surgical challenge. Electrode mapping, especially in the young child, is difficult given the uncertainty of electrode contact with viable neural elements. This paper reviews surgical technique and the use of auditory brainstem responses to map the electrodes. A 4-year-old child deafened by meningitis at age 20 months had bilateral cochlear ossification by computed tomography. At surgery, a canal wall-down mastoidectomy and closure of the ear canal were performed. A trough around the modiolus was drilled, and the electrode array was placed in it. Post-operatively, the patient gave aversive or no responses to electrode stimulation. To assess electrode function, auditory brainstem responses to individual electrode activation were obtained under general anesthesia. Functioning electrodes could thus be selected for mapping. The patient now responds well to sound.

Intact canal wall mastoidectomy with tympanoplasty for cholesteatoma in children.

OBJECTIVE/HYPOTHESIS: Cases of cholesteatoma in pediatric patients were reviewed to determine which factors influence the outcome of surgical treatment. Cholesteatoma is considered a more aggressive disease in children than in adults. The outcomes of intact canal wall (ICW) mastoidectomy and canal wall down (CWD) mastoidectomy were assessed, as comparisons of different surgical technique. STUDY DESIGN: A retrospective analysis of all cases of pediatric cholesteatoma treated at a single institution by the senior author (P.R.L.) over a period of 11 years was conducted. METHODS: Patient information was collected from an otology database, patient records, and audiology files. RESULTS: Sixty-six patients, aged 10 months to 18 years, were treated and followed for an average of 37.7 months (range 12.2 months to 12.5 y). ICW mastoidectomy with tympanoplasty was the primary surgical treatment in 41 patients. Nineteen percent had residual disease at a planned second stage surgery and 22% developed recurrent cholesteatoma for a total recidivism rate of 41%. A SRT of less than 30 dB HL was achieved in 75% of these patients. Seventeen patients underwent CWD mastoidectomy with tympanoplasty initially. Two patients (12%) had residual cholesteatoma found at a planned second state procedure, and no recurrent cholesteatoma was encountered. Seventy-two percent maintained a SRT of less than 30 dB HL. CONCLUSIONS: These results support the continued use of ICW mastoidectomy with tympanoplasty for pediatric cholesteatoma. If planned second stage surgery is necessary, the long-term results of an ear with useful hearing and few problems with chronic medical care are gratifying. For reasons of anatomy or in an only hearing ear, CWD mastoidectomy with tympanoplasty provides a safe ear and good hearing results. Mastoid cavity care must be maintained indefinitely in many cases.

Osteoma of the internal auditory canal.

OBJECTIVE: To review presenting symptoms and illustrate management options for this uncommon lesion. DESIGN: Case series and literature review. SETTING: Tertiary referral center. PATIENTS: Three cases of osteoma of the internal auditory canal are presented. Additional cases from the literature, diagnosed by radiographic appearance or gross description, are included for comparison. MAIN OUTCOME MEASURE: Response of clinical symptoms. RESULTS: Presenting symptoms are highly variable. Available reports do not adequately define the natural history of the lesion. CONCLUSION: The lack of a consistent presentation despite a similar radiographic appearance suggests that the osteoma is often an incidental finding.

Light microscopic evidence of hair cell regeneration after gentamicin toxicity in chick cochlea.

This study examines the temporal pattern of hair cell loss in the chick basilar papilla following ten days of gentamicin administration in hatchling chicks. Chicks were subsequently killed at ages 11, 18, 25, and 32 days. The basilar papillae were embedded in plastic and serially sectioned for light microscopic analysis. Hair cell counts were obtained at 100-microM intervals throughout the length of the papilla. Significant hair cell loss was documented basally in the 11-day-old chicks, and spread apically over time to maximal loss in the 18-day-old animals. Relative to the control chicks, there was a 36% hair cell loss in these animals. Interestingly, there appears to be a progressive partial recovery of the normal hair cell counts in the 25- and 32-day-old animals.

Meningitis and facial paresis. Implications for cochlear implantation.

Most postlingually deafened individuals receive auditory sensations with a cochlear implant. We describe a postmeningitic patient with bilateral facial paresis who failed to be stimulated with a multichannel device. In light of the facial dysfunction, primary auditory nerve damage by meningitis is postulated as the cause of implant failure. Preoperation electrical stimulation of the cochlea using an alternating current signal is recommended as a means of assessing cochlear implant candidacy.

Primary lymphoma of the temporal bone.

Involvement of the temporal bone by lymphoreticular neoplasm is rare; all reported cases have been of secondary involvement. This article presents what we believe to be the first two reported cases of primary temporal bone lymphoma. The patients, an elderly man and a boy, both presented with infection of the ear, hearing loss, and facial nerve paresis. In both cases, facial paresis resolved after appropriate chemotherapeutic treatment. Patient presentation and clinical course are discussed in light of published work on temporal bone malignancy. Further investigation, including computed tomography and biopsy, should be considered for patients who present with an apparent middle ear infection unresponsive to medical therapy. The development of facial paralysis in such a patient warrants heightened suspicion of malignancy.

Promontory electrical stimulation in labyrinthectomized ears.

Bilateral deafness can occur in patients with Menière's disease who have undergone a labyrinthectomy in one ear. To investigate the feasibility of a cochlear implant in the labyrinthectomized ear, promontory electrical testing by transtympanic needle was performed in six patients who had undergone a unilateral transmastoid labyrinthectomy 6 weeks to 5 years previously. All patients had a behavioral response to the stimulus, and each described a different pitch percept with the four frequencies used. Five of the patients demonstrated an electrically evoked middle latency response. These data are comparable with behavioral and electrophysiologic responses from ears deafened by other causes and now successfully implanted. The results suggest that peripheral neural elements and central auditory pathways remain at least partially functional many years after a labyrinthectomy. Thus, a labyrinthectomy should not be withheld as a surgical option if otherwise indicated.

Trends in rehabilitation after cochlear implantation.

Although postimplant rehabilitation is generally considered to be an important aspect of a cochlear implant program, the literature reports widely varying practices in the implementation of such programs. The National Institutes of Health consensus statement on cochlear implantation (May 1988), while recognizing that aural rehabilitation facilitates maximal use of the implant, offers no specific guidelines or recommendations. A questionnaire survey was made of over 200 otolaryngologists to determine current practices in a variety of aspects of their cochlear implant programs. Results were obtained from a total of more than 1400 patients, including adults, adolescents, and children. Rehabilitation is an integral part of the cochlear implant program in the vast majority of active programs surveyed. General aspects of cochlear implant programs, as well as those of rehabilitation programs in particular, are discussed.

The interaction of noise and aspirin in the chick basilar papilla. Noise and aspirin toxicity.

The possible synergism between noise and aspirin for causing cochlear damage was examined histologically. Six chicks fed aspirin for five days and five chicks fed a normal diet only were paired and placed in sound chambers. They were exposed to a 1500-Hz tone at 115 dB sound pressure level for eight hours. The mean serum salicylate level just before noise exposure was 24 mg/dL (1.74 mmol/L). Ten days later they were killed, and the temporal bones were processed. Hair cell counts were made at 100-microns intervals throughout the length of the basilar papilla (cochlea). The noise produced a discrete cochlear lesion centered about 30% of the distance from the base to apex. The addition of aspirin did not significantly alter the extent or location of this lesion. One aspirin-fed chick had a unilateral middle ear effusion, and a striking shift in the center of damage toward the apex was noted in this cochlea.

Cranial fasciitis presenting as an external auditory canal mass.

Cranial fasciitis is a rare benign lesion that develops in childhood. It is considered a subset of nodular fasciitis but occurs selectively in the scalp of children. A review of the world literature revealed only 22 other published cases and no previous reports of a lesion involving the petrous portion of the temporal bone or presenting as a mass in the external auditory canal. We report a rare case of cranial fasciitis in the petrous portion of the temporal bone of a neonate and present a review of the literature.