Timo I. Marttila

Results of audiometrical screening in Finnish schoolchildren

The results of pure tone screening in Finnish schoolchildren in the Helsinki University Central Hospital District (Finland) during the years 1978-81 were assessed. 40,824 children were screened at a screening level of 20 dB (HL) (ISO). 11.4% of the children failed the first screening procedure. A control screening in these children was performed at 2- to 4-week intervals. A total of 1563 children did not pass the second screening (3.8% of the whole screened population). 1485 schoolchildren were then referred to an otologist. 32% of the children referred had normal hearing. In total, 2.5% of the population screened really had impaired hearing. The hearing loss was conductive in 41%. Negative middle ear pressure (less than -150 daPa) occurred in 7% of the referred children. In the middle ear cleft, fluid was noticed in 11%. High-frequency losses comprised 25% of the cases referred. Sensorineural hearing impairment affecting speech frequencies was present in 8%. The pure tone screening is considered important, because even slight abnormalities in hearing acuity can reduce the intelligibility of speech message and cause learning problems. Surgically manageable middle ear disorders should be detected. Occasionally, a sensorineural loss was discovered, requiring fitting of a hearing aid.

Cochlear Blood Flow Measurement in Patients with Me´nie`re's Disease and Other Inner Ear Disorders

To identify an eventual vascular aetiology in different diseases with sensorineural hearing loss (SNHL), the cochlear blood flow (CoBF) was measured using laser Doppler flowmetry (LDF) in 69 patients with Ménières disease (MD), 38 patients with progressive SNHL and 8 patients with sudden deafness. The mean CoBF amplitude at rest was 0.70 mV (SD 0.25) for patients with MD, 0.66 mV (SD 0.21) for patients with SNHL and 0.69 mV (SD 0.23) for those with sudden deafness. No statistically significant difference was observed between the groups with respect to the CoBF amplitudes at rest or during the Valsalva manoeuvre. There was a statistically significant correlation (r = -0.4, p < 0.05) between the hearing level and CoBF amplitude in the SNHL group only. It is concluded that the reduction in vascular flow may not be the main aetiological factor in Ménières disease or sudden deafness. In SNHL the correlation of hearing level with the level of the LDF amplitude can be secondary to the progression of hearing loss.To identify an eventual vascular aetiology in different diseases with sensorineural hearing loss (SNHL), the cochlear blood flow (CoBF) was measured using laser Doppler flowmetry (LDF) in 69 patients with Ménières disease (MD), 38 patients with progressive SNHL and 8 patients with sudden deafness. The mean CoBF amplitude at rest was 0.70 mV (SD 0.25) for patients with MD, 0.66 mV (SD 0.21) for patients with SNHL and 0.69 mV (SD 0.23) for those with sudden deafness. No statistically significant difference was observed between the groups with respect to the CoBF amplitudes at rest or during the Valsalva manoeuvre. There was a statistically significant correlation ( r = -0.4, p < 0.05) between the hearing level and CoBF amplitude in the SNHL group only. It is concluded that the reduction in vascular flow may not be the main aetiological factor in Ménières disease or sudden deafness. In SNHL the correlation of hearing level with the level of the LDF amplitude can be secondary to the progression of hearing loss.

Prevalence of Childhood Hearing Impairment in Southern Finland

The Department of Audiology in Helsinki University Central Hospital provides paedoaudiological services for the Province of Uusimaa, including Helsinki. Our purpose was to study the prevalences of hearing threshold loss in children born in the period 1973 to 1990. The material consisted of 353 hearing-disabled children. The pure-tone average (0.5, 1 and 2 kHz) of the better ear was the parameter for hearing threshold. In 36 subjects the hearing acuity was determined with the behavioural observation test or the brainstem electric response measurement. The number of hearing-impaired per birth year (hearing level > or = 35 dB) ranged from 6 to 30 and the prevalence rate from 0.3 to 1.9 in 1000, totalling 1.1. After matching the hearing-impairment criteria with those of the previous reports from northern Sweden, Denmark and the European Community, we were able to compare the prevalences.

Incidence of virus infection as a cause of Meniere's disease or endolymphatic hydrops assessed by electrocochleography

Meniere’s disease (MD) may follow viral infection such as by neurotropic viruses known to invade the endolymphatic sac (ES) and provoke endolymphatic hydrops (EH). The objective of this study was to investigate whether neurotropic viruses may cause infection of the inner ear and provoke EH. Antiviral immunoglobulin (IgG) assay against herpes simplex 1 (HSV1), herpes simplex 2 (HSV2), adenovirus (ADV), varicella zoster virus (VZV) and cytomegalovirus (CMV) were performed in 109 patients with an advanced stage of MD and compared with those obtained from 26 patients operated on because of vestibular schwannoma (VS), who served as a control group, to evaluate whether there is an association between the IgG levels and the ECoGs summating potential/action potential ratio (SP/AP ratio) in the MD group. In MD patients, the IgG titre against VZV and ADV were significantly higher than in the control (schwannoma) group. However, no correlation was found between the IgG levels against ADV and VZV with the SP/AP ratio. Neurotropic viruses such VZV and ADV may play a role in the pathogenesis of MD, despite the absence of association between the levels of IgG titres and the SP/AP ratio

Role of Transtympanic Endoscopy of the Middle Ear in the Diagnosis of Perilymphatic Fistula in Patients with Sensorineural Hearing Loss or Vertigo

Background: The diagnosis of perilymphatic fistula (PLF) is often difficult, and therefore the condition can be overlooked. Tympanoscopy presents an alternative procedure for visualising the middle ear anatomy, and it may help to diagnose PLF. Aim: The aim of this study was to evaluate the use of middle ear endoscopy in establishing the diagnosis of PLF and in defining its incidence in patients with sensorineural hearing loss and/or vertigo and tinnitus. Subjects and Methods: Two hundred and sixty-five patients (22–80 years of age, mean 48 years) were prospectively and consecutively referred for middle ear examination with tympanoscopy. Tympanoscopy was performed using endoscopes with visual angles of 5 and 25° and an outer diameter of 1.7 mm. The round window niche (with its secondary membrane), the oval window with a stapes superstructure, a part of the facial recess and the area in the fissula ante fenestram were examined and video-recorded. Results: For 1 patient, tympanoscopy revealed fistula in the round window membrane that was covered with a fibrinous layer. In 4 cases abnormal mucosal shining appeared in the round window, but no PLF was present. In 7 cases the tympanic cavity could not be visualised because of the adhesive tympanic membrane, abnormal anatomy or the prominent exostoses of the external ear canal. In 6 cases a postendoscopic middle ear infection was found. No permanent tympanic membrane perforation occurred in any of the patients in this study. Conclusions: Tympanoscopy is a rapid examination tool with which to verify certain areas of the middle ear anatomy, but it is of limited value for ruling out the presence of PLF.

Comparison between audiometric and ABR thresholds in children. Contradictory findings

The aim of the study was to predict hearing level thresholds with click-evoked ABR and to study the residual hearing when ABR was absent. In 85 hearing-impaired children, the conclusive pure-tone hearing level thresholds are reported. The exclusion criterion used was deteriorating hearing loss. The Jewett V-wave was identified in 48.2% of the subjects and was bilaterally absent in 51.8%. The correlation between ABR and PTA (2–4xa0kHz) thresholds was significant ( P <0.01). Audiometrically, 65.9% of the children with no response on ABR had hearing, and in 34.5% of these, the hearing loss was sloping. The median PTA (2–4xa0kHz) was 102xa0dB and the range from 65 to 120xa0dB. The accuracy of ABR is reasonably ineffective, because it overestimates the hearing loss in moderate and severe impairments. The absence of ABR indicates a significant hearing loss, but PTAs (2–4xa0kHz) as good as 65xa0dB were still found. Thus, a lack of response to click stimuli does not directly suggest none-viable residual hearing.

Identification of childhood hearing impairment in Uusimaa County, Finland

The purpose was to report the identification age of the hard-of-hearing children born between 1 January 1973 and 31 December 1990. The subjects comprised all children (353) fitted with hearing aid in an age-matched target population of 270 726 persons in Uusimaa County including Helsinki. The age of identification was studied in three groups; pure tone average (0.5, 1 and 2 kHz) > or = 30 dB, > or = 35 dB and > or = 50 dB HL enabling comparison with the identification ages reported in the literature. In the first group the median identification age was 3.6 years (mean 4.2), in the second 2.9 years (mean 3.8) and in the third 2.1 years (mean 2.8). The first group was identified significantly later than the third one (P = 0.004). The second group differed from the third significantly in detection age as well (P = 0.004). The severity of hearing impairment correlated highly with the detection age (r = -0.69. P < 0.0001). The data clustered at the ages of 1-2.5 years (hearing level 90-120 dB) and at 4-8 years (30-60 dB).

Auditory Pathway Function after Vestibular Schwannoma Surgery

We studied seven patients before and after vestibular schwannoma surgery. Four patients became unilaterally profoundly deaf and three patients preserved their hearing. Cortical responses were recorded with a 122-channel whole-scalp SQUID neuromagnetometer using tone-burst stimuli to the healthy ear. Brainstem auditory evoked potentials (BAEPs) were measured using alternating clicks. Ten healthy volunteers served as a control group. In patients, preoperative cortical response latencies and strengths did not differ significantly from those of controls. However, 6 months after the operation the latency was, on average, 7 ms longer than preoperatively over both hemispheres. BAEPs were in the normal range both before and after the operation. These results suggest that unilateral lesion in peripheral auditory pathways also affects cortical reactivity to stimuli presented to the non-affected ear, possibly reflecting altered binaural interaction in the auditory pathways.We studied seven patients before and after vestibular schwannoma surgery. Four patients became unilaterally profoundly deaf and three patients preserved their hearing. Cortical responses were recorded with a 122-channel whole-scalp SQUID neuromagnetometer using tone-burst stimuli to the healthy ear. Brainstem auditory evoked potentials (BAEPs) were measured using alternating clicks. Ten healthy volunteers served as a control group. In patients, preoperative cortical response latencies and strengths did not differ significantly from those of controls. However, 6 months after the operation the latency was, on average, 7 ms longer than preoperatively over both hemispheres. BAEPs were in the normal range both before and after the operation. These results suggest that unilateral lesion in peripheral auditory pathways also affects cortical reactivity to stimuli presented to the non-affected ear, possibly reflecting altered binaural interaction in the auditory pathways.

Hearing Disability Assessment in Evaluating Hearing Aid Benefit

The aim was to study the applicability of an eight-item questionnaire in evaluating the benefit derived from hearing-aid use. Since 1977, 3402 hard-of-hearing patients have been fitted with a hearing aid for the first time and followed up for 3 months in the Helsinki University Central Hospital. The questionnaire included eight situation-specific items in hearing: speech face-to-face, speech in a small and large group, loud speech, in telephone and radio/TV, doorbell, telephone signal. The scoring ranged from 0 to 16. After a 3 months use of amplification, the questionnaire was completed again. The median (interquartile range) and arithmetic mean (standard deviation) of the prefitting scores were 5.0 (4.0-6.0) and 5.3 (2.33). The postfitting scores were 1.0 (0.0-2.0) and 1.1 (1.17), respectively. The difference was highly significant. An eight-item questionnaire in the evaluation of hearing problems provided a reliable numerical score of disability. Follow-up is important to secure satisfactory results in rehabilitation, especially in old age.

Behavioural Observation Audiometry in Testing Young Hearing-Impaired Children

The aim was to examine the accuracy of unconditioned behavioural observation audiometry (BOA) in predicting hearing acuity in children and the validity of test results at various frequencies. The study was designed to longitudinally compare each childs best BOA response level (at the age >12 months) with the conclusive pure-tone threshold of the better ear. The subjects were 119 children derived from a material of 353 children fitted with a hearing aid at Helsinki University Central Hospital. BOA was carried out on 119 children, 19 of whom did not respond to frequency-specific stimuli. The predictive power of BOA depended on the severity of hearing loss. At the hearing level of 30-39 dB, BOA registered 10-15 dB poorer levels than the pure-tone audiometry. The pure-tone averages (0.5, 1, 2 kHz) of 50-69 dB agreed best with the BOA responses. In severe impairments (more than 70 dB HL), the BOA registered too good hearing. Correlation of the results from the two modes to measure hearing level was highly significant (r = 0.71, p = 0.000), and the pure-tone hearing level agreed with that of BOA at the frequencies 0.5 to 4 kHz. Our results show that BOA averages < or =30 dB rarely indicate hearing loss demanding fitting of a hearing aid.