Auditory function among young occupational divers: a 3-year follow-up study.

Auditory function was measured in a 3-year follow-up study of 54 young occupational divers divided into high-exposure (n = 23) and low-exposure (n = 31) groups. The divers performed open-sea dives with a median number of 132 dives (range 44-766) during follow-up. At the start of follow-up, hearing in the high-exposure group was reduced compared with that in the low-exposure group. During the follow-up period, the total group experienced a significantly reduced hearing ability at 4 kHz in the left ear. No difference in change between the last and the first measurement for both ears combined was found when the two groups were compared. A regression analysis of measurements at the end of follow-up shows an association between the loss of hearing in the left ear at 6 and 8 kHz and the total number of years of diving. This indicates that diving may contribute to hearing impairment.

Arctic charr (Salvelinus alpinus) vitellogenin: development and validation of an enzyme-linked immunosorbent assay.

Vitellogenin (Vtg) was isolated from plasma of estradiol-17 beta-treated Arctic charr males by double precipitation with MgCl2-EDTA and distilled water, followed by ion-exchange chromatography. The monomeric form of Vtg, as revealed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was 158 kDa. The purified Vtg was used to raise a polyclonal antibody for Vtg (AbVtg), and the specificity of the AbVtg was assessed by Western blot analysis. No cross-reactivity was observed with plasma from control males. Using this AbVtg, a competitive enzyme-linked immunosorbent assay was developed. The detection limit of the assay was 2 ng ml-1, and the intra- and inter-assay variations determined from plasma samples were 8.6 and 13.3%, respectively. The assay was validated by quantification of Vtg in plasma samples obtained during a reproductive cycle of Arctic charr. Vtg of females increased gradually from 3 mg ml-1 in early March to a peak value of 22 mg ml-1 in late August, followed by a rapid drop to 2 mg ml-1 at the time of spawning in mid-October. The temporal changes in plasma Vtg of females correlate well with the reproductive cycle. Vtg was undetectable in males, except on some sampling dates during July-September when minute amounts (3-13 micrograms ml-1) were detected in some individuals.

[Tinnitus--etiology, diagnosis and treatment]. / Tinnitus--etiologi, diagnose og behandling.

Tinnitus is the sensation of sound, a sensation generated by the auditory system because of a pathology, without any external acoustic or electrical stimulation. 15% of the adult population have experienced shorter or longer periods of tinnitus. Three percent of these, in total about 7,000-10,000 persons in Norway, suffer from continuous tinnitus followed by symptoms that demonstrate handicap or occupational disability. The authors discuss the cause of tinnitus and its relation to different kinds of hearing loss. Treatment is dependent on a specific diagnosis. There is no universal medical or surgical treatment. Today, cognitive therapy is emphasised, to the tinnitus patients to understand what causes the tinnitus, to accept the condition and to inform them about relaxation techniques. Physical therapy and training are also emphasised. Active treatment with regular counselling can reduce the occupational and social disabilities.

Transient-evoked otoacoustic emissions. Helpful tool in the detection of pseudohypacusis.

The object of the present study was to demonstrate the use of TEOAEs for diagnosing pseudohypacusis. Thirty-four patients were investigated for suspected pseudohypacusis based on the case history and clinical and audiological findings. TEOAEs confirmed the diagnosis in all cases except four patients with a pre-existing organic hearing loss exceeding 25-30 dB HL. All the remaining 30 patients showed normal TEOAE responses except four of the ears in which final assessment revealed hearing threshold lower than 30 dB in the middle frequency region. The method can be time-saving when performed at the first consultation. With its element of surprise, the patient can be confronted with the existence of a functional hearing loss. This frequently results in marked threshold improvement on repeat pure-tone audiometry.

Transient evoked otoacoustic emissions as screening for hearing losses at the school for military training.

The present study was designed to investigate the applicability of transient evoked otoacoustic emissions (TEOAEs) as a method of screening for hearing losses among recruits attending obligatory military service. TEOAEs, tympanometry and puretone audiometry were recorded in 95 male recruits. Sixty-one recruits were tested after a 2-month period of gunfire exposure in order to document any permanent change in cochlear function. Screening by pure-tone audiometry showed an unexpectedly high prevalence of hearing losses > 20 dBHL, probably due to technical reasons. Thresholds were corrected using lower thresholds obtained at the end of service or by ENT specialists. The accuracy with which normal and impaired ears could be identified with TEOAEs analysed in frequency bands was determined by decision theory. Impairment was defined as mean hearing thresholds > or = 30 dBHL averaged from three neighbouring frequencies. Adequate accuracy was obtained in the middle frequencies. Further improvement of the technique is needed before it can be deemed suitable for detecting hearing losses at low and high frequencies. TEOAEs are quicker to measure and offer greater objectivity than pure-tone audiometry. A small decrease in TEOAE level was found after the training period. The TEOAEs were highly repeatable and had a higher sensitivity than pure-tone audiometry to detection of small changes in cochlear function under conditions normally found when testing recruits.

Temporary threshold shift and otoacoustic emissions after industrial noise exposure.

The objective of the present study was to investigate whether employees in a noise-exposed environment developed changes in cochlear function as manifested by elevation of pure-tone threshold and/or reduction in transient evoked otoacoustic emission (TEOAE) amplitude. Pure-tone air-conduction audiometry, otoacoustic emissions (OAEs) and tympanometry were recorded in 13 healthy employees on three consecutive days both before and after 7 h of noise exposure. Employees exposed to an industrial noise level of 85-90 dBA developed significant pure-tone air-conduction threshold elevation at 4 and 6 kHz. A significant reduction of the TEOAE amplitude was found. There was no correlation between temporary threshold shift (TTS) and TEOAE reduction.

Reproducibility and short-term variability of transient evoked otoacoustic emissions.

The reproducibility and short-term, less than 3 days, variability of transient evoked otoacoustic emissions (TEOAEs) were studied in 23 young, otologically healthy subjects engaged either in strenuous physical exercise or relatively sedentary occupations. Tympanometry was also performed. TEOAEs were highly reproducible. No differences were found between the two subject groups, nor any significant diurnal variations in TEOAE amplitudes. The latter were, however, significantly (p = 0.005) correlated to middle ear pressures. Tympanometry should therefore be performed in studies of possible intrinsic or extrinsic influences on TEOAE amplitudes.

Otoacoustic emissions in the first year of life.

Transient evoked otoacoustic emissions (TEOAEs) were successfully recorded in 192 ears of 100 consecutive full-term neonates tested on the third or fourth postnatal day. A follow-up study was performed in 35 of these infants at the ages of 3, 6 and 12 months. The number of infants presenting decreased linearly with postnatal age. TEOAE amplitudes were largest in the youngest age group. Both the time required for testing each infant and the number of ears in which TEOAEs could not be identified increased with age. Otomicroscopical changes indicating secretory otitis media were found in all the latter ears. Recording of TEOAEs is a suitable method for screening peripheral auditory function in infants, and can be most successfully performed at the age of 3 or 4 days.

Hearing impairment in Oslo born children 1989-91. Incidence, etiology and diagnostic delay.

An investigation of incidence, etiology and diagnostic delay was performed in Oslo born children referred to the audiological department of Ullevål Hospital in the period 1989-91; hearing loss in these children required amplification and audiopedagogical training. An increase in incidence compared with 1975-84 was found. No child had a hearing loss caused by rubella. The age at time of diagnosis is increased, with a median age of 28 months. Children with moderate hearing losses are diagnosed at later ages. A considerable delay in the diagnosis of hearing-impaired children is shown.

Feed intake, growth and osmoregulation in Arctic charr, Salvelinus alpinus (L.), transferred from freshwater to saltwater at 8°C during summer and winter.

The purpose of the current study was to examine seasonal changes in seawater tolerance and growth performance of anadromous Arctic charr (Salvelinus alpinus L.) held at the same temperature (8°C) during winter and summer. Charr (20-27 cm), previously reared in freshwater under natural photoperiod, were transferred either directly (DT) from freshwater to seawater (35 ppt), from freshwater to brackish water (20 ppt), or were gradually adapted (GT) to seawater over a period of 10 days. Control fish were held in freshwater. Feed intake and osmoregulatory ability were then monitored on three occasions during the following 59 days. Two experiments were carried out, one during winter (December-January) and the other during summer (June-July). In both experiments fish mortality was low. Plasma osmolalities recorded in fish transferred to seawater were within normal ranges, but osmolalities on day 10, were significantly lower in summer (313 mOsm/kg (DT), 328 mOsm/kg (GT)) than in winter (323 mOsm/kg (DT), 352 mOsm/kg (GT)). In winter, feed intake and growth rates were high in fish kept in fresh and brackish water, but charr transferred directly to seawater ate little and lost weight. Fish that were gradually adapted to seawater occupied an intermediate position. During summer the observed differences in feed intake were small and all fish had relatively high growth rates. These results suggest that Arctic charr display seasonal changes in feed intake and growth performance that parallel seasonal changes in hypoosmoregulatory capacity. The ability to survive and hypoosmoregulate in full strength seawater does not, however, seem to be a particularly good indicator of successful seawater adaptation with respect to the ability to display high rates of feed intake and growth. During winter, a gradual transfer to seawater appeared to lead to improved feeding and growth compared to direct transfer.

[Otoacoustic emissions]. / Otoakustiske emisjoner.

Otoacoustic emissions provide a new method for objective assessment of peripheral auditory function. Emissions have been recorded in 80 patients and comparisons made with subjective hearing tests and brain stem response audiometry. Our experiences confirm that this procedure is rapid and easy to perform, and that the presence of emissions is a reliable indication of normal function in the middle ear and cochlea. This is particularly useful in neonates, young children and adults whose inability to cooperate prevents the use of behavioural audiometry. Recording of otoacoustic emissions can replace brain stem response audiometry as the primary objective assessment of auditory function in these groups.

Phenoxymethylpenicillin two or three times daily for tonsillitis with beta-haemolytic streptococci group A: a blinded, randomized and controlled clinical study.

In relation to compliance problems it was investigated whether phenoxymethylpenicillin dosed twice or 3 times daily was equally effective in tonsillitis due to beta-haemolytic streptococci group A. In a randomized, controlled and single blind multicentre study 206 patients older than 5 years with a positive culture of group A streptococci were treated with phenoxymethylpenicillin for 7 days. 101 patients received the daily dosage divided in 2 doses and 105 patients divided in 3 doses a day. The cure rate (a combination of bacteriological and clinical cure) was 82.0% in the 2-dosage regimen, and 88.2% in the 3-dosage regimen. The difference was not statistically significant. In conclusion, phenoxymethylpenicillin dosed 2 or 3 times daily seems to be equally effective in tonsillitis due to group A streptococci.

Phenoxymethylpenicillin two or three times daily in bacterial upper respiratory tract infections: a blinded, randomized and controlled clinical study.

In relation to compliance problems it was investigated whether phenoxymethylpenicillin dosed 2 or 3 times daily was equally effective in bacterial upper respiratory infections. In a randomized, controlled and single blind clinical trial, 131 patients with otitis media, sinusitis and tonsillitis were treated with phenoxymethylpenicillin. 71 received the daily dose twice a day and 60 patients received the daily dose 3 times a day. The dose was adjusted for diagnoses and age. Clinical cure was the endpoint for treatment success. In the 2-dosage group 78.6% had full effect of the treatment and 86.2% had full effect in the 3-dosage group. There was no statistically significant difference. In conclusion phenoxymethylpenicillin dosed 2 or 3 times daily seems to be equally effective in bacterial upper respiratory infection.

[Hearing loss among children in Oslo]. / Hørselhemmede oslobarn.

The study concerns children born the years 1975-84. Only children in need of hearing aids are taken into account. The incidense was 1.08 per 1,000 live born children. The prevalens in January 1988 was 1.57 per 1,000 children, including 18 children moving into the city. The etiology among 75 children was 47% prenatal, 16% perinatal, 11% postnatal defects and further 26% of unknown neurogenic origin. Among the 63 impaired children living in Oslo 1988 15 or 24% had multiple handicaps. Identification of hearing loss before one year of age increased from 23% for children born 1975/79 to near 60% for children born 1980/84. At risk children should be tested before leaving hospital after delivery.