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Biomedical subjects

J D Clemis

Publications and source records attributed to J D Clemis.

At least 19 recordsLinked to original sources
PubMed1991

Electromagnetic semi-implantable hearing device: phase I. Clinical trials.

Conventional hearing aids have improved significantly in recent years; however, amplification of sound within the external auditory canal creates a number of intrinsic problems, including acoustic feedback and the need for a tight ear mold to increase usable gain. Nonacoustic alternatives which could obviate these encumbrances have not become practical due to inefficient coupling (piezoelectric techniques) or unfeasible power requirements (electromagnetic techniques). Recent technical advances, however, prompted a major clinical investigation of a new electromagnetic, semi-implantable hearing device. This study presents the details of clinical phase I, in which an electromagnetic driver was coupled with a target magnet temporarily affixed onto the lateral surface of the malleus of six hearing aid users with sensorineural losses. The results indicate that the electromagnetic hearing device provides sufficient gain and output characteristics to benefit individuals with sensorineural hearing loss. Significant improvements compared to conventional hearing aids were noted in pure-tone testing and, to a lesser degree, in speech discrimination. Subjective responses were quite favorable, indicating that the electromagnetic hearing device 1. produces no acoustic feedback; 2. works well in noisy environments; and 3. provides a more quiet, natural sound than patients' conventional hearing aids. These favorable results led to phase II of the project, in which patients with surgically amendable mixed hearing losses were implanted with the target magnet incorporated within a hydroxyapatite ossicular prosthesis. The results of this second-stage investigation were also encouraging and will be reported separately.

Acoustics↗
PubMed1990

The geriatric auditory and vestibular systems.

Age-related declines in auditory and vestibular function are becoming more prevalent and better understood. The personal and societal impact of these disorders is impressive, and present techniques of amplification or balance training can be of great benefit. However, many issues await investigation, and continued integration of ever-increasing technologies promises many new answers, and questions, in the future.

Aging↗
PubMed1979

Monothermal upright-inverted caloric test.

This study evaluates the diagnostic sensitivity of a simple method of producing bidirectional cupular deviation using a monothermal stimulus. This stimulus has the advantage of conservation of time and increased patient comfort and acceptance (two caloric irrigations instead of four). Each patient was seated with his head extended 60 degrees during the caloric irrigation. Eighty seconds after the onset of irrigation, the patient placed his head forward, thereby causing both an ampullopetal and ampullofugal flow of endolymph. Right/left difference and directional preponderance were computed for both monothermal warm and monothermal cold irrigations and compared to the traditional bithermal caloric results. This study comprised a control group of 13 normal patients and 144 dizzy patients. False positive (abnormal monothermal but normal bithermal) and false negative (normal monothermal but abnormal bithermal) tests occurred in 45 percent and 50 percent of examinations, respectively. Inaccurate measurement of the weak slow phase velocity that usually accompanies the inverted position was a probable cause of the poor correlation between test results since a separate analysis of electronystagmograms with more intense nystagmus in the inverted position resulted in an improved correlation. Further evaluation of this technique should include methods that result in more accurate measurement of slow phase velocity.

Adolescent↗
PubMed1978

The large vestibular aqueduct syndrome.

The radiographic observation of 50 patients, each having an enlarged (greater than 1.5 mm. diameter) vestibular aqueduct, are analyzed. In addition to the aqueduct other associated inner ear anomalies have been identified in 60% of this population including: enlarged vestibule (14); enlarged vestibule and lateral semicircular canal (7); enlarged vestibule and hypoplastic cochlea (4); and hypoplastic cochlea (4). The large equeduct then presumably represents an arrested phase of inner ear development common to all 50 cases. Only 8 of these cases may fall into the Mondini or Mondini-Alexander classification wherein cochlear abnormalities have been identified. The size of the aqueduct ranged from 1.5 to 8 mm. in the anteroposterior diameter; the clinical incidence is 50 in 3700 consecutive cases referred for inner ear tomography. Bilateral involvement is twice as common as unilateral with a female to male predominance of 3:2. Most cases are associated with congenital hearing losses.

Adult↗
PubMed1977

Acinic cell tumors of salivary gland origin.

The acinic cell tumor of salivary gland origin, once thought to be benign, is now known to be an incidiously slow growing malignant neoplasm with lethal potential. While the degree of malignant behavior of individual acinic cell tumors is notably variable, all must be treated with aggression. Traditional and current methods of treatment are reviewed; and, in conjunction with the tumors herein reported, guidelines for managment of this uncommon malignancy are suggested. Four cases have been reviewed in detail and critically analyzed. The pathology, including features of both light and electron microscopy, in included--particularly in relation to the oncocytoid areas identified in from 10% to 40% of the parenchymal cells of our tumors. Since an accurate histopathologic diagnosis is the first step in the establishment of a proper treatment plan, pitfalls in histologic diagnosis have been stressed.

Adult↗
PubMed1977

Normal opaque cerebellopontine cisternogram.

An attempt has been made through this study to establish a tumor suspect pool of 100 patients, each one highly suspect because of a single or usually several strong clinical indicators of a retrocochlear lesion. In turn each patient has been proven tumor negative by virtue of a normal opaque cerebellopontine cisternogram. This has given us a unique opportunity to critically reassess the clinical indications of VIIIth nerve tumor from a reverse or negative viewpoint. All data from these patients has been carefully analyzed in relation to indication for opaque cisternography, clinical symptomatology, vestibular function, final etiologic diagnosis, and the associated special auditory tests, tomograph of the internal auditory canal, the associated vestibular aqueduct findings. This paper parallels our earlier study of 121 surgically proven schwannomas providing a total tumor suspect pool of 221 patients with a comparable tumor positive-tumor negative distribution.

Audiometry↗
PubMed1977

Temporal bone histopathology of Paget's disease with sensorineural hearing loss and narrowing of the internal auditory canal.

A temporal bone report is presented of a patient with progressive sensorineural hearing loss and advanced Paget's disease involving the skull. The histopathology reveals Pagetic bone invading the internal auditory canal and compressing the cochlear division of the VIIIth cranial nerve resulting in severe neural degeneration. There are no other histopathologic abnormalities present in the cochlea to explain the hearing loss. A low-frequency conductive hearing loss was also present, but no histopathologic correlate could be identified.

Aged↗
PubMed1977

Audiograms derived from the brain stem response.

Nineteen normal and 22 hearing impaired subjects were used in this study. Thresholds were determined by the following methods: 1. behavioral continuous tone, 2. behavioral tone burst, and 3. the brain stem electric response (BER) with tone bursts. A comparison of the BER thresholds with the behavioral thresholds are made for each subject. The difference between these three measures of threshold suggests that audiograms can be derived from the brain stem response threshold. The derived audiogram compares favorably with conventional audiograms. However, it must be remembered that the brain stem response is not hearing.

Auditory Threshold↗
PubMed1976

Special audiometric test battery in 121 proved acoustic tumors.

The usefulness of a special audiometric test battery was analyzed in relation to overall and individual test efficiency for the diagnosis of retrocochlear disease. Data were collected and analyzed from 118 patients with 121 surgically confirmed acoustic neuromas and were compared with an earlier report of 200 similar cases. While audiologic testing plays a major role in the identification of retrocochlear disease, the test battery is not highly efficient. Eleven percent of our neuromas had no audiologic signs and, therefore, escaped audiologic detection. The efficiency of individual tests range from 47% to 77%, while the difference in efficiency between the tone-decay test (77%) and the entire battery (89%) indicates the continued need for more than one test. The low efficiency of some of the components justifies reappraisal and revision of the present test battery.

Audiometry↗
PubMed1976

Hydrocephalus following translabyrinthine surgery.

Hydrocephalus has been identified and surgically treated with ventricular peritoneal shunts in two of 150 patients following translabyrinthine microsurgical removal of acoustic tumors. This problem has prompted a review of the subject of hydrocephalus in general and "otitic hydrocephalus" in particular in relation to contemporary extended temporal bone surgery.

Aged↗
PubMed1975

Intramuscular hemangioma in the head and neck.

Intramuscular hemangioma is a distinct type of hemangioma occurring within skeletal muscle and making up less than one per cent of all hemangiomas. They occur most often in the trunk and extremities, perhaps beacuse of the larger muscle volume in thos areas. 13.5 per cent of intramuscular hemangiomas do occur in the head and neck region and for this reason they should be considered in the differential diagnosis of head and neck masses. The first case of an intramuscular hemangioma of the digastric muscle is presented and confirmed by electron microscopic sections. An interesting finding in this tumor is the proliferation of both endothelial cells and pericytes. Hemangiomas are classified according to vessel size; "large vessel" cavernous, "small vessel" capillary, and "mixed". Various etiologies and modalities of treatment are discussed, and total excision with ligation of the feeding vessels is advocated to prevent the high incidence of later recurrence.

Adult↗
PubMed1975

Ultrastructural characteristics of human neurilemoma cell nuclei.

Nuclei of human neurilemoma cells exhibit deep and extensive invaginations of part of their surface. Such invaginations contain cytoplasmic matter. However, in areas of the nucleoplasm distant from the invaginations, small membrane-bound bodies, some of which contain a "nucleoid," occur either singly or grouped together and enclosed within a large membrane body. These small bodies are not considered virus-like. Degenerated nuclei from cultured tumor tissue contain spherical bodies, 130 to 230 nm in diameter, with spikes on their surface similar to those seen on envelopes of herpes-type viruses. Significance of these bodies in vivo and in vitro tumor tissues is not known.

Cell Nucleus↗