Biomedical subjects
Publications and source records attributed to W F House.
The perfect cochlear implant has eluded the many research teams around the world that are studying it. In the hope that someone may develop one system that is clearly better than the others, I believe that each team should pursue its own ideas and methods. We have at least another 20 years of step-by-small step development if we are to continue to improve the cochlear implant.
Three hundred five acoustic neuromas were reviewed to determine the sensitivity of combining the auditory brainstem response (ABR) and the intravenous contrast-enhanced computed tomogram (CT) as screening tests for acoustic neuroma diagnosis. The ABR detected 98% of the tumors. The enhanced CT demonstrated 97% of tumors larger than 1.5 cm, but only 48% of neuromas 1.5 cm or smaller. The combination of both ABR and enhanced CT, used as the initial screening tests, identified 99% of the neuromas. We conclude that ABR, with enhanced CT as needed, is an accurate screening protocol. This method can be used as an alternative to the traditional ABR, electronystagmography, and internal auditory canal tomograms.
The clinical audiometric test results from 53 postlingually deafened adults using the House single-channel cochlear implant were analyzed according to cause of deafness (otosclerosis, ototoxic drugs, meningitis, and trauma). With the exception of one measure, the routine clinical tests did not show a relationship between cause of deafness and performance with the cochlear implant. These findings suggest that, clinically, the single-channel cochlear implant is a viable prosthesis for patients with a wide variety of causes of deafness.
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Auditory percepts can be produced by electrical stimulation of the cochlear nucleus in man. The ability to locate accurately and stimulate selectively the cochlear nucleus after removal of an acoustic schwannoma was confirmed in this patient. The surgical approach, electrode design, and a discussion of the results and concerns of electrical stimulation are reviewed.
The experience of our group in the management of 1667 patients with the diagnosis of an acoustic neuroma has been reviewed. Certain features of the operation have been discussed. It is our feeling at this time that with the techniques available to the neuro-otologist for the management of patients harboring acoustic neuromas, the goals of surgery should be total removal of the tumor with preservation of the facial nerve and avoidance of injury to the adjacent important brain structures. Our patients, at this time, should reasonably expect this type of result from their surgery. Hearing preservation in the above framework continues to be frustrating and difficult to consistently attain, and obviously remains the next barrier in acoustic tumor surgery.
Schwannomas of the jugular foramen are relatively uncommon tumors. The growth and initial presentation of these tumors are variable and may not be associated with neuropathies of cranial nerves IX, X and XI. Seven patients with jugular fossa schwannomas are presented. Auditory brain stem response, electronystagmogram, computed cranial tomography, and carotid angiography are helpful in diagnosis and preoperative evaluation. The surgical approach should be individualized to the lesion and may include transmastoid with extended facial recess, translabyrinthine, retrolabyrinthine, and infratemporal/cervical approaches.
Acoustic tumor surgery provided an ideal model in which to study possible contralateral hearing loss following a destructive surgical procedure on the inner ear. Follow-up audiometric studies were performed on patients with unilateral acoustic tumors who had undergone resection of their tumors. Patients who had obvious causes for contralateral hearing loss, such as chronic otitis media, unrelated otologic surgery, and noise-induced hearing loss, were excluded from this patient population. A total of 380 patients had available pre- and postoperative audiograms. A mean air-conduction threshold (500, 1000, 2000 Hz) of greater than or equal to 20 dB was considered a significant hearing loss. After adjusting these losses for presbycusis, 1.3% of these patients still had a significant contralateral hearing loss. We discuss the possible causes for the development of contralateral hearing loss and examine the possibility that, following surgical manipulation and injury to the inner ear, immunocompetent cells become sensitized to previously unseen inner ear antigens, setting the stage for contralateral inner ear dysfunction. The similarities of this condition to sympathetic ophthalmia are discussed.
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Twenty-five children deafened by meningitis were compared with 10 congenitally deaf children on cochlear implant performance. All subjects had met the audiologic criterion of profound deafness as required for implant surgery. Twenty subjects in the meningitis group had some degree of ossification at the round window, and drilling was required for electrode insertion into the scala tympani. In six of these subjects, bone completely filled the scala. There was a significant relationship between extensive ossification and the etiologic pathogen Diplococcus pneumoniae, as determined by radiologic and surgical reports. Postoperative results revealed that all subjects could be electrically stimulated, except for one with extensive bone formation. On implant performance, the meningitis group demonstrated sound-field thresholds comparable to those of the group with congenital deafness but required significantly higher voltage settings. These findings suggest that even with extensive labyrinthine ossification caused by meningitic deafness, neural elements are present and can be stimulated if enough power can be safely provided.
Extensive clinical investigation of the cochlear implant, both in adults and children, has provided evidence of significant benefit with relatively minimal risk. Work is in progress world-wide to develop improved cochlear implant device. Meanwhile, an auditory prosthesis is now available for the profoundly deaf patient who could not be successfully treated in the past. It is the result of interaction between medicine and engineering, and represents a new approach to the treatment of profound deafness.
Extensive clinical investigation of the cochlear implant, both in adults and children, has provided evidence of significant benefit with relatively minimal risk. Work is in progress worldwide to develop improved cochlear implant devices. Meanwhile, an auditory prosthesis is now available for the profoundly deaf patient who could not be successfully treated in the past.
Carcinoid tumours belong to the rarest neoplasms of the middle ear. Murphy et al. (1980) described an interesting carcinoid tumour of the middle ear displaying adenomatous features. The histological similarity of carcinoid tumours to adenomatous tumours of the middle ear has also been noted by Fayemi and Toker (1975). We describe a similar case which caused certain diagnostic difficulties. Light microscopy on frozen sections favoured the diagnosis of a low-grade adenocarcinoma but electron microscopy has revealed the presence of many intracellular membrane-bound neurosecretory granules and the diagnosis was revised to that of a mixed carcinoid tumour.
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Whether or not attacks of Meniere's disease are related to ruptures in the membranous labyrinth is still a point of contention. To help clarify this point, we used light microscopy to study the membranous labyrinth in 14 temporal bones with hydrops from patients with Meniere's disease, four bones with hydrops from patients without Meniere's disease, and 11 normal bones. Findings suggest that ruptures are specific to bones with hydrops from patients with Meniere's disease and that they occur more frequently in Reissner's membrane than in the vestibular membranes.
The condition of central neurofibromatosis, while well documented in neurology literature, has tended to be amalgamated into acoustic neuromas associated with peripheral neurofibromatosis (or Recklinghausen's disease) in otolaryngology literature. The history of a unique family that has demonstrated four generations of bilateral acoustic neuromas has been outlined to show that central neurofibromatosis is a distinct entity related but not identical in clinical and biochemical aspects to Recklinghausen's disease. This article in intended to acquaint the otolaryngologist with the presentation and management of central neurofibromatosis.
In many of the reports dealing with disorders of the human inner ear the histology comes from temporal bone dissection. In the past decade the scanning electron microscope has changed, to a degree, the approach to inner ear investigation. However, many problems remain with adequate preservation of specimens from human temporal bones. Ordinarily, human material is obtained from cadavers at autopsy as soon as possible after death, and postmortem changes are evident. At the Otologic Medical Group, Inc., in Los Angeles, many translabyrinthine operations for acoustic neuromas are performed. This report covers findings from vestibular specimens obtained during surgery for removal of acoustic neuromas (four cases) and during eighth nerve surgery (one case).
The cochlear implant offers an alternative to selected profoundly deaf patients in whom conventional treatments or prostheses have been unsuccessful. Substantial benefits have been obtained by patients, with apparently minimal risk. There have been no serious surgical complications and only a few postoperative problems, which were remedied satisfactorily. The device has continued to function in patients over a period of years, and in cases of internal coil failure it has been removed and replaced. Replacement devices seem to function as well as the patient's first device. There has been no evidence of any decrement in performance after years of electrical stimulation or any measurable adverse effects. The cochlear implant is now widely available and should be considered an option to be offered to appropriate patients.