Biomedical subjects

D F Konkle

Publications and source records attributed to D F Konkle.

7 recordsLinked to original sources

PubMed1990

Vision and hearing during deferoxamine therapy.

To determine the frequency of eye and auditory complications and their relationship to drug dosage and iron stores in patients receiving deferoxamine, we studied 52 regularly transfused patients who received deferoxamine by subcutaneous or intravenous infusion in doses from 26 to 136 mg/kg/day, and whose serum ferritin levels of 185 to 17,775 micrograms/L reflected a wide range of iron stores. Forty-nine patients (94%) had no evidence of drug-induced visual or auditory abnormalities. Symptomatic loss of vision and hearing developed in one patient; both problems improved when chelation therapy was stopped. Of the 51 symptom-free patients, one had a mild degree of macular stippling and one had a mild, bilateral, high-frequency sensorineural hearing loss. Eye and ear abnormalities in the symptom-free patients did not progress despite continuation or resumption of chelation therapy at the same dosage. Patients with ophthalmologic and audiologic abnormalities did not receive higher doses of deferoxamine and did not have lower serum ferritin levels than patients without such abnormalities. These findings demonstrate that eye and ear abnormalities during chelation therapy with deferoxamine may not occur uniformly at as high a frequency as previously reported, even in patients who receive large doses of the chelating agent or who have only modest amounts of excessive iron.

Adolescent↗

PubMed1987

Cholesteatoma in the pediatric patient.

A review of patients with cholesteatoma at the Children's Hospital of Philadelphia from 1981 to 1986 yielded 161 children. Analysis of data from both outpatient and hospital charts revealed a higher incidence of males to females, and the peak incidence of cholesteatoma appeared to be in the 6-10 year age group. Otorrhea was the most common symptom; and on physical examination, the posterior-superior quadrant was most often affected. Both intact canal wall and open cavity procedures were employed depending upon the site and extent of disease. Seventy-six percent of patients underwent an intact canal wall or middle ear procedure initially, with the remainder requiring an open cavity procedure. Recurrent or residual cholesteatoma was found in 32% of 148 patients at the second procedure, and in 7% of 148 patients if a third procedure was necessary. Pre- and post-operative audiometric findings for 91 patients revealed 21% with decreased hearing post-surgically, 50% with no change in hearing and 29% with improved hearing. Post-operative complications were minimal.

Adolescent↗

PubMed1986

ABR screening of high-risk infants: effects of ambient noise in the neonatal nursery.

This investigation examined ABR waveforms obtained at five signal intensities (20, 30, 40, 60, and 80 dB nHL) for adults and at three signal intensities (20, 40, and 80 dB nHL) for infants. ABR recordings were obtained in a quiet condition and repeated for three different intensity levels (40, 50, and 60 dBA) of background noise characteristic of a neonatal intensive care unit. The subjects were ten adults and ten infants whose ABRs were judged normal when measured at 20 dB nHL in the quiet condition. Results indicated that high levels of ambient noise (up to 60 dBA) did not influence either absolute wave V or interwave latencies measured for stimulus intensities of 60 and 80 dB nHL. ABR waveforms obtained at stimulus intensities often used for screening (i.e., 20, 30 or 40 dB nHL), however, were substantially altered for some subjects as a function of increasing levels of ambient noise. This observation was most apparent for the infant population and has important implications for the design of infant ABR screening programs.

Adult↗

PubMed1979

Meningitis and hearing loss in children.

The hospital records for 100 cases of meningitis in which acute audiometric data has been obtained were reviewed. The incidence of sensorineural hearing loss was found to be 6%. The severity of hearing impairment varied from mild to profound and was frequently bilateral and irreversible. Two-cases showed asymmetrical involvement, and in one case, there was subsequent improvement in threshold sensitivity. Factors that influenced the incidence of neurologic sequela included severity of the initial disease process, age of the patient, and duration of symptoms before diagnosis and treatment. We discuss the pathophysiologic mechanisms that may account for such hearing loss, and we emphasize the importance of early diagnosis and intensive antimicrobial therapy. Careful neurologic evaluation is required after recovery and must include periodic sequential audiometric testing.

Age Factors↗

PubMed1979

The development of middle-ear admittance in the hamster.

A high-frequency admittance meter was developed and used to study the maturation of physiological function in the middle ear of neonatal golden hamsters (Mesocricetus auratus). The middle-ear input admittance in the frequency range of 0.8-1.8 kHz was measured in animals ranging in age from 6 to 69 days postpartum. Admittance magnitude was found to increase steadily with age, beginning on day 16, to asymptotic values at each test frequency. There were no obvious differences in admittance growth rates within the range of frequencies tested. However, an analysis of the slopes of the admittance ma;nitude frequency response curves revealed an increase from 4.6 dB/octave for animals 25 days old or younger, to 6.3 dB/octave for all older animals. This difference between younger and older subjects indicates that the development of the middle ear in the golden hamster is more complex than a simple increase in pure compliance.

Acoustic Impedance Tests↗

PubMed1977

Intelligibility of time-altered speech in relation to chronological aging.

The Northwestern University Auditory Test Number 6 (NU-6) measure of speech discrimination was time compressed and presented to four age groups ranging from 54 to 84 years of age. Experimental stimuli were presented at sensation levels of 24, 32, and 40 dB to an equal number of right and left ears and male and female subjects. Results indicated that intelligibility decreased as a function of increasing time compression and age and decreasing sensation level. Changes in speech intelligibility associated with the aging process appear to be closely allied to changes in the temporal resolving power of the central auditory processing system.

Adult↗

PubMed1977

Central auditory imperception.

The development of clinically applicable techniques for the evaluation of hearing impairment caused by lesions of the central auditory pathways has increased clinical interest in the anatomy and physiology of these pathways. A conceptualization of present understanding of the anatomy and physiology of the central auditory pathways is presented. Clinical tests based on reduction of redundancy of the speech message, degradation of speech and binaural interations are presented. Specifically performance-intensity functions, filtered speech tests, competing message tests and time-compressed speech tests are presented with the emphasis on our experience with time-compressed speech tests. With proper use of these tests not only can central auditory impairments by detected, but brain stem lesions can be distinguished from cortical lesions.

Animals↗