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Biomedical subjects

D Osterhammel

Publications and source records attributed to D Osterhammel.

14 recordsLinked to original sources
PubMed1987

Cumulative and acute toxicity of repeated high-dose tobramycin treatment in cystic fibrosis.

Forty-six patients with cystic fibrosis and chronic bronchopulmonary Pseudomonas aeruginosa infection entered a study of tobramycin-related chronic and acute nephro- and acousticovestibular toxicity. The patients (mean age, 15.7 years) had previously received 2-week courses of tobramycin therapy, for a mean cumulative total of 279 days each. The cumulative tobramycin dose ranged from 632 to 7,644 mg/kg. The patients were studied before and at the end of a 2-week course of treatment with tobramycin (10 to 20 mg/kg per day) to discriminate between acute and chronic toxicity. In patients studied at the beginning of the present course of treatment, the glomerular filtration rate, measured as 24-h creatinine clearance, did not correlate with the cumulative dose of tobramycin received during previous courses. Eighteen patients (39%) had a reduced glomerular filtration rate compared with normal values (mean, 12.5% reduction) but normal serum creatinine values. Two patients (5%) had a high-frequency hearing deficit (above 8 kHz), but only one deficit was possibly related to tobramycin. No chronic vestibular toxicity was observed. During the course of treatment, no patients developed acute nephrotoxicity. After 2 weeks of treatment 32% had a slightly reduced hearing threshold (15 to 30 dB) in two or more high frequencies, and 28% had a fall in vestibular response greater than 25% of the initial value but remained within normal limits. Thus, the acute and chronic toxicity of repeated high-dose tobramycin treatment in cystic fibrosis patients seems to be very mild.

Adolescent↗
PubMed1984

Caloric testing with small temperature gradients. Caloric zero.

Caloric nystagmus was investigated in 50 normal subjects with stimulation of the temperatures 30, 33, 35, 39, 41, and 44 degrees C. Mean values of the duration and the eye speed of the slow phase of adjacent temperatures were significantly different. No difference could be demonstrated between the equidistant temperatures 30/44 and 35/41 degrees C, but the response was significantly stronger with 35 than with 39 degrees C. This indicates that the caloric zero, i.e., the theoretical neutral temperature, is higher than 37 degrees C. The caloric zero was determined by extrapolation of the regression lines of the mean values for the six temperatures investigated. Determination by means of maximum eye speed of the slow phase values showed to be more accurate than with the duration, probably due to smaller interindividual variations of the responses.

Adolescent↗
PubMed1980

High frequency audiometry and stapedius muscle reflex thresholds in juvenile diabetics.

Sixty-one juvenile, insulin-treated diabetics below 50 years of age with a duration of diabetes mellitus longer than 10 years underwent impedance audiometry with determination of stapedius reflex thresholds at 500 Hz, 1, 2, and 4 kHz, conventional pure tone and speech audiometry, and high-frequency audiometry up to 20 kHz. The results were compared with a normative material of non diabetic subjects selected after exactly the same criteria. No significant differences in hearing or stapedius reflex thresholds were found. Among half of the subjects there was a diabetic retinopathy. A comparison between those with and those without retinopathy did not reveal any significant difference in audiological findings. Even subjects with severe diabetic complications and almost life-long diabetes had normal hearing. Recent investigations on plasma-lipoids have discussed the possibility that insulin might prevent a premature ageing of hearing which has been reported by other authors. It is concluded that no statistical data exist that confirm a correlation between hearing impairment and diabetes.

Acoustic Impedance Tests↗
PubMed1980

High frequency audiometry. Clinical aspects.

For 2 years past a previously described quasi-free-field high frequency audiometer delivering pure tones from 4 to 20 kHz has been incorporated in the audiological test battery. By this technique it is possible to obtain reliable and reproducible thresholds above the age of 8--9 years. In several case histories it is illustrated how high frequency audiometry (HFA) contributes to a better audiological diagnostic and it is predicted that HFA is of value in research studies on presbycusis, ototoxicity, noise vulnerability, and in hereditary studies on deafness. The physiological presbycusis demands normative reference values for each age decade. Many other factors, however, can cause an impaired high frequency hearing which is a severe limitation to the diagnostic value of abnormal findings.

Adult↗
PubMed1980

Audiological findings in children with a congenital rubella syndrome.

This is a report of the hearing in 22 consecutive children seen in an audiology clinic because of intrauterine infection with rubella-virus. The diagnosis of congenital rubella may be difficult and sometimes impossible to make retrospectively. It is often a probability diagnosis made by a combination of laboratory tests and various deformities in the heart, the central nervous system, the eyes, and the inner ear. Audiometrically the findings are very much differentiated, and there is no typical configuration. The results reported in a scientific paper from USA mentioning a relatively good high-frequency hearing in some "profoundly deaf" patients have not been found by audiometry up till 20 kHz in a small group of severely hearing impaired rubella-children. But there is reason to suppose that some persons with a hereditary type of hearing impairment may have a relatively well preserved hearing in the high-frequency field.

Audiometry↗
PubMed1979

High-frequency audiometry. Age and sex variations.

286 normal subject representing both sexes and seven age groups from 10 to greater than or equal to 70 years were tested with both conventional pure tone audiometry and high frequency audiometry (4--20 kHz) using a previously described free field system. The subjects were selected according to very strict criteria. Results from conventional audiometry are similar to other findings in presbycusis studies, though sex difference was seen for the oldest age groups, but only at the frequencies 4 and 5 kHz where the male population showed a significantly poorer hearing. The same sex difference was observed by high frequency audiometry at 4 and 8 kHz. From 10--20 kHz no sex difference was present. At the high frequencies there is an abrupt decrease in hearing sensitivity already from youth. Hitherto, no international standard for zero dB hearing level exists for frequencies above 8 kHz. It is questioned whether a general standard is meaningful at all and that normative data for various age groups should instead be used as a reference level.

Adolescent↗
PubMed1979

High-frequency audiometry and noise-induced hearing loss.

A group of noise-exposed male subjects with an audiogram that is characteristic for noise trauma were submitted to high-frequency audiometry (HFA) up to 20 000 HZ. The results were compared with those obtained in a group of normally hearing persons with no history of noise exposure. Conserved high frequency hearing was found. Very strict selection criteria were applied in both groups in order to avoid hereditary diseases and to ensure normal middle ear function. The findings are in good overall agreement with histological findings in noise-exposed animals and also with high-frequency studies in the older literature. Two illustrative case stories from patients with severe 4--6 kHz dips are reported, one with preserved high-frequency hearing in spite of a considerable acoustic trauma and one with extreme sensitivity towards noise and with no hearing at all in the high frequencies. It is concluded that 1) HFA cannot be used as an early indicator of the traumatic effect of high intensity noise; 2) presbycusis and noise damage may be additive elements in the older age groups (above 50 years); 3) persons with abnormal high-frequency hearing are possibly hypersensitive towards excessive noise and HFA might be useful in the routine audiological evaluation of workers before these are exposed to noise.

Adult↗
PubMed1978

High-frequency thresholds using a quasi-free-field technique.

A free-field transducer system for high-frequency audiometry was applied on two groups of otologically normal, non noise-exposed subjects tested at the frequencies 4--8--10--12--14--16--18--20 kHz. The former group consisted of 46 children 10--12 years old and the second group of 40 adults aged 18--24 years. All participants in the youngest group were able to hear 20 kHz and no difference between right and left ear or between sex could be shown. A similar result was found in the adult group except that 4 males were unable to hear 20 kHz. Hearing thresholds for the two groups were almost identical at 8--14 kHz. Above this frequency range the youngest group showed a statistically significant lower threshold at 18 and 20 kHz. This group might be used for a zero-dB hearing threshold level in further high-frequency studies. The advantage of transferring the SPL value from the entrance to ear canal to absolute ear drum pressure level is discussed.

Adolescent↗
PubMed1977

A quasi-free-field transducer system for high-frequency audiometry.

Previous attempts to measure human hearing capacity in the high frequencies (8 to 20 kHz) have only been met with rather limited success. Based on the results of Shaw and co-workers we have developed a free-field transducer system where the stimuli are delivered from a point source and meet the ear as plane progressive waves at a carefully chosen angle of incidence. The system can be calibrated in a precise manner by means of a specially designed coupler. Preliminary results indicate that the procedure is easily applicable also in a group of inexperienced test subjects and the test-retest variability was within such limits that are acceptable for subjective audiometric testing. These results require validation in a large group of subjects and we hope it will be possible to establish normative values for various age groups.

Audiometry↗