Hormones and the auditory system: a review of physiology and pathophysiology.

This review explores the potential role of hormones in modulating the auditory function. The review describes four groups of hormones (the hormones of the circadian cycle, reproduction, stress response and the fluid and electrolyte balance), their physiological variations, interactions, as well as the physiological basis for their effect on the auditory system. Possible contribution of hormones to pathophysiology of auditory dysfunctions, including hyperacusis, tinnitus, Menière's disease and pre-menstrual auditory dysfunction, has also been discussed.

Community-based infant hearing screening for early detection of permanent hearing loss in Lagos, Nigeria: a cross-sectional study.

OBJECTIVE: To determine the feasibility and effectiveness of a community-based universal infant hearing screening programme for detecting permanent congenital and early-onset hearing loss (PCEHL) in Lagos, Nigeria. METHODS: This is a cross-sectional study in which all infants aged 3 months or under attending four bacille Calmette-Guérin (BCG) immunization clinics accounting for over 75% of the BCG coverage in the study location were screened by community health workers between July 2005 and April 2006. Screening followed a two-stage protocol involving transient evoked otoacoustic emissions and automated auditory brainstem responses. The main outcome measures were screening coverage, referral rates, return rates for second-stage screening and evaluation, yield and age at PCEHL diagnosis. FINDINGS: In total, 2003 (88%) of 2277 eligible infants attending the four BCG clinics were successfully screened between July 2005 and April 2006 at a mean age of 17.7 days, with no parent declining screening. The majority (55.2%) were born outside a hospital and, of such infants, 77% were born in traditional herbal maternity homes. The overall referral rate for diagnostic evaluation was 4.1%. Only 61% (50/82) of those referred returned for evaluation, and 45 of them were confirmed with PCEHL. Additionally, 11 infants who had previously passed the first screening stage were also found to have PCEHL, resulting in a yield of 28 per 1000 (56/2003). The mean age at diagnosis was 51 days. The sensitivity, specificity and positive predictive value of the first screening stage were 80.4%, 99.7% and 90.0%, respectively. The positive likelihood ratio was 268, while the negative likelihood ratio was 0.2. CONCLUSION: Routine hearing screening of infants attending BCG immunization clinics by community health workers was feasible and effective for the early detection of PCEHL in Lagos, Nigeria. However, an efficient tracking and follow-up system is needed to improve return rates for second-stage screening and diagnostic evaluation.

Non-hospital delivery and permanent congenital and early-onset hearing loss in a developing country.

OBJECTIVE: The objective of this study was to determine the role of non-hospital delivery and other risk factors for permanent congenital and early-onset hearing loss (PCEHL) in a developing country. DESIGN: Matched case-control study. SETTING: Four primary healthcare centres in inner-city Lagos, Nigeria. POPULATION: Fifty-six infants with PCEHL and 280 normal hearing controls matched for age and sex from a population of infants not older than 3 months attending Bacille de Calmette-Guérin immunisation clinics. METHODS: Conditional logistic regression analyses of infant and maternal characteristics associated with PCEHL, and the evaluation of population exposure to each risk factor. MAIN OUTCOME MEASURES: Adjusted matched odds ratios and population attributable risk percent (PAR%). RESULTS: Children with PCEHL were significantly more likely to be first born (OR 1.9, 95% CI 1.1-3.6) without skilled attendants at birth (OR 2.4, 95% CI 1.3-4.5) and have a history of neonatal jaundice requiring exchange blood transfusion (NNJ/EBT) (OR 9.6, 95% CI 2.4-38.2) but less likely to be small for gestational age (SGA) (OR 0.1, 95% CI 0.0-0.5). After controlling for other covariates, the absence of skilled attendants at birth (OR 4.2, 95% CI 2.0-8.6) and NNJ/EBT (OR 19.1, 95% CI 4.3-85.5) emerged as predictors of PCEHL, while SGA (OR 0.1, 95% CI 0.0-0.2) retained its inverse relationship with PCEHL. The PAR% was 35.9% for the lack of skilled attendants at birth and 10.6% for having NNJ/EBT. About 23% of children with PCEHL did not exhibit any risk factors. CONCLUSIONS: NNJ/EBT and the absence of skilled attendant at birth rather than the place of delivery are significant predictors of PCEHL in this study population. Targeted hearing screening using these risk factors would facilitate the detection of about 77% of children with PCEHL.

Hospital-based universal newborn hearing screening for early detection of permanent congenital hearing loss in Lagos, Nigeria.

OBJECTIVE: To determine the feasibility and effectiveness of hospital-based universal newborn hearing screening programme for the early detection of permanent congenital or early-onset hearing loss (PCEHL) in Lagos, Nigeria. METHODS: A cross-sectional pilot study based on a two-stage universal newborn hearing screening by non-specialist health workers using transient evoked otoacoustic emissions (TEOAE) and automated auditory brainstem-response (AABR) in an inner-city maternity hospital over a consecutive period of 40 weeks. The main outcome measures were the practicality of screening by non-specialist staff with minimal training, functionality of screening instruments in an inner-city environment, screening coverage, referral rate, return rate for diagnosis, yield of PCEHL and average age of PCEHL confirmation. RESULTS: Universal hearing screening of newborns by non-specialist staff without prior audiological experience is feasible in an inner-city environment in Lagos after a training period of two-weeks. Notwithstanding excessive ambient noise within and outside the wards, it was possible to identify a test site for TEOAE screening within the hospital. The screening coverage was 98.7% (1330/1347) of all eligible newborns and the mean age of screening was 2.6 days. Forty-four babies out of the 1274 who completed the two-stage screening were referred yielding a referral rate of 3.5%. Only 16% (7/44) of babies scheduled for diagnostic evaluation returned and all were confirmed with hearing loss resulting in an incidence of 5.5 (7/1274) per 1000 live births or a programme yield of 5.3 (7/1330) per 1000. Six infants had bilateral hearing loss and the degree was severe (> or =70 dB nHL) in three infants, moderate (40 dB nHL) in one infant and mild (<40 dB nHL) in two infants. The age at diagnosis ranged from 46 days to 360 days and only two infants were diagnosed within 90 days. CONCLUSIONS: Hospital-based universal hearing screening of newborns before discharge is feasible in Nigeria. Non-specialist staff are valuable in achieving a satisfactory referral rate with a two-stage screening protocol. However, a more efficient tracking and follow-up system is needed to improve the return rate for diagnosis and age of confirmation of hearing loss.

Maternal views on infant hearing loss in a developing country.

BACKGROUND: Parental support for infant hearing loss is essential for a successful infant screening programme. However, in developing countries where unfavourable customs and beliefs towards childhood disabilities have been reported, parental support towards infant screening is uncertain and there is presently no published evidence on the subject. OBJECTIVE: To elicit the views of mothers and would-be mothers in order to ascertain their knowledge on infant hearing loss and their attitudes towards infant hearing screening. METHODS: A structured questionnaire consisting of 15 questions was administered to 101 mothers (mean age 31.6+/-7.3 years, range: 21-55 years) attending two community hospitals in Lagos, Nigeria. The responses were evaluated by descriptive statistics, factor analysis of the principal components and multiple regression analysis. The reliability of the two main domains (knowledge and attitude) was tested for internal consistency by Cronbach's alpha coefficient. RESULTS: Maternal knowledge was highest for measles (73%; mean score 2.54) and ear discharge (73%; mean score 2.51) but low for birth asphyxia (37%; mean score 1.90), traditional medicine (42%; mean score 2.03) and jaundice (47%; mean score 2.09) as causes of hearing loss. Attitude towards neonatal screening was positive in majority of mothers (92%; mean score 2.84) and there was a high acceptance of hearing aids as an early intervention option (84%; mean score 2.70). Five factors (eigenvalue>1) were extracted after principal component analysis with the attitude variables loading highly and exclusively on one factor. Age was the only demographic variable that was associated with a domain (knowledge) after multiple regression analysis. The component scales for the two domains were highly internally consistent (alpha coefficients of 0.84 and 0.83). CONCLUSIONS: Contrary to the concerns often expressed about parental support for infant hearing screening programmes in developing countries, this study suggests that current parental knowledge and attitude favour early detection and intervention of childhood hearing impairment.

Mining balance disorders' data for the development of diagnostic decision support systems.

In this work we present the methodology for the development of the EMBalance diagnostic Decision Support System (DSS) for balance disorders. Medical data from patients with balance disorders have been analysed using data mining techniques for the development of the diagnostic DSS. The proposed methodology uses various data, ranging from demographic characteristics to clinical examination, auditory and vestibular tests, in order to provide an accurate diagnosis. The system aims to provide decision support for general practitioners (GPs) and experts in the diagnosis of balance disorders as well as to provide recommendations for the appropriate information and data to be requested at each step of the diagnostic process. Detailed results are provided for the diagnosis of 12 balance disorders, both for GPs and experts. Overall, the reported accuracy ranges from 59.3 to 89.8% for GPs and from 74.3 to 92.1% for experts.

Screening for early childhood hearing loss in Nigeria.

Newborn hearing screening has been recognized as an essential component of public health care in early childhood in developed countries. However, such screening is yet to be widely embraced in the developing world. The new national health policy in Nigeria seeks, for the first time, to reduce the impact of permanent hearing loss on early childhood development through early detection and timely intervention services. The aim of this paper is to ascertain if newborn hearing screening satisfies the conventional criteria for a screening programme as an early detection strategy in this developing country. A review of the available literature shows that permanent childhood hearing loss is a significant health condition and its detection through screening with oto-acoustic emissions and/or auditory brainstem response is feasible in the target population. Amplification with hearing aids is an effective and preferred option for early intervention by parents. The risk of maternal anxiety from potential false-positives or the psychological cost of false assurance from false-negatives is unlikely to outweigh the benefit of screening. Newborn hearing screening is therefore a potential early detection strategy for permanent childhood hearing loss in Nigeria.

On the relationship of CSF pleocytosis to immunoglobulin levels as estimated by different techniques.

One might expect a positive correlation between the number of CSF lymphocytes and the relative amount of CSF IgG, especially in cases of local synthesis of IgG within the CNS. However, previous attempts at correlating the number of CSF lymphocytes with IgG levels have yielded varying results. Since it is known that the estimation of CSF IgG levels can vary according to the method of immunoglobulin determination used, we decided to perform the analyses by three separate methods: (1) the commonly used, immunoprecipitation technique of radial immunodiffusion; (2) physico-chemical separation on the basis of hydrated size/charge using alkaline electrophoresis through the molecular sieving effects of polyacrylamide gels, followed by densitometry of the gamma region of Coomassie Blue-stained proteins; (3) separation into constituent Ig heavy chains and light chains on the basis of unfolded chain lengths by molecular sieving using sodium dodecyl sulphate (SDS), followed by densitometry of heavy chains of immunoglobulins having been labelled with the fluorescent dye dansyl chloride. Our results show a correlation of white count with the latter two techniques but not the former. Possible reasons for discrepancies in the literature are discussed with regard to the peculiar physical properties of the selected CSF IgG molecules.

Pendred syndrome--100 years of underascertainment?

Pendred syndrome is an autosomal recessive condition classically characterized by deafness and goitre. Since both cochlear and thyroid pathology are required to secure the diagnosis, it is unclear whether the condition might present without the classical features. The perchlorate discharge test, the gold-standard investigation for Pendred syndrome, is non-specific, and in the absence of alternative means of confirming the diagnosis, its sensitivity is unknown. We used the recent mapping of the gene to chromosome 7q to identify pedigrees with a likely diagnosis of Pendred syndrome, and assessed the prevalence of clinical parameters of disease in affected patients. Thirty-six familial cases showed co-segregation between disease and the Pendred syndrome locus on chromosome 7q. Clinical and investigative findings were compared in index cases (n = 18) vs. affected siblings (n = 18). The overall prevalence of goitre was 73%, higher in index cases (94%) than in siblings (56%), many of whom had not previously been considered to have the condition. One perchlorate discharge test was false-negative (2.9%). Radiological malformations of the cochlea were identified in 86% of cases. Securing a diagnosis of Pendred syndrome may be difficult, especially in the single case. The perchlorate discharge test, although valuable, is difficult to undertake in the younger patient, and radiology may assist in diagnosing such patients.

Dizziness following head injury: a neuro-otological study.

Dizziness is a frequent and debilitating complications of head injury and accounts for increasing numbers of medico-legal claims. A detailed neuro-otological study was carried out from the records of 100 patients with post-traumatic dizziness to explore the neuro-otological basis of their symptoms: 50 patients presenting for medico-legal purposes (group I) and 50 presenting for management of their vestibular symptoms (group II). The two groups showed a similar sex distribution, a similar range of causes of head injury and similar severity of head injury (72 minor, 24 moderate and 4 severe). Of the 100, 88 showed at least one audio-vestibular abnormality on testing. Vertigo of the benign positional paroxysmal type was the commonest vestibular diagnosis in both groups (61/100), and only 8 patients showed central vestibular abnormalities. Fifty-three patients had audiometric abnormalities attributable to the head injury, the commonest of which was a high-tone sensorineural hearing loss. There was no significant difference in the incidence of any of the abnormalities in the medico-legal group (group I) when compared with the symptom management group (group II). The results provide strong evidence for an organic basis to recurring dizziness after head injury, whether or not a claim for compensation is pending, and emphasize the need for specialist neuro-otological investigation if abnormalities are to be identified and managed correctly.

Bilateral loss of vestibular function: clinical findings in 53 patients.

The clinical presentations and aetiologies of a series of 53 cases of bilateral vestibular failure (BVF) seen by the authors over a decade were evaluated by retrospective review of the medical records. Thirty-nine per cent of patients had associated neurological disease; 13% had a progressive cerebellar syndrome with disabling gait ataxia, abnormal eye movements and cerebellar atrophy on neuro-imaging. BVF was usually unsuspected. Nine per cent had cranial or peripheral neuropathies and in this group there was no abnormality of brain stem/cerebellar oculomotor function, but hearing loss was common. Eleven per cent revealed BVF and hearing loss secondary to meningitis, and 6% had other neurological disorders. Idiopathic BVF was found in 21% of cases, characterised by paroxysmal vertigo and/or oscillopsia, but no abnormal clinical signs. Gentamicin ototoxicity accounted for a further 17%, while autoimmune disease was present in 9% of patients. Otological or neoplastic disease was diagnosed in the remaining 13% of patients. It was concluded that neurological, audiological and ocular motor assessments allow the probable cause of BVF to be defined in approximately 80% of cases. A group of BVF related to autoimmune pathologies is reported for the first time, indicating the need for immunological screening. Idiopathic BVF may present with only minor visual or vestibular symptoms, while in patients with cerebellar degeneration, BVF may be unsuspected and, thus, underdiagnosed.

Subarachnoid hemorrhage and papilledema due to a cervical neurilemmoma. Case report.

An unusual case of a cervical neurilemmoma is presented. A 67-year-old man developed papilledema on two occasions in association with the symptoms and signs of a subarachnoid hemorrhage (SAH). He proved to have an otherwise asymptomatic cervical neurilemmoma. It is suggested that both acute and subclinical bleeding from such tumors may sometimes underlie the development of raised intracranial pressure occasionally encountered. The clinical clue to the spinal origin of the SAH was an acute onset with root pain. This case is discussed with reference to similar cases in the literature.

Symptoms, anxiety and handicap in dizzy patients: development of the vertigo symptom scale.

Questionnaires assessing symptoms, anxiety and handicap were completed by 127 vertiginous patients. Factor analysis identified four distinct symptom clusters which formed the basis for the construction of scales quantifying the number and frequency of symptoms of: (a) vertigo (of long and short duration); (b) autonomic sensations and anxiety arousal; and (c) somatization. Scores on the vertigo severity scale were significantly related to clinical diagnosis and had near-zero correlations with measures of anxiety. Vertigo severity, autonomic signs and depressed mood each independently contributed to variance in handicap, taking precedence over the relationship between handicap and trait and state anxiety. Our findings suggest that the familiar association between anxiety and vertigo may be mediated principally by autonomic symptomatology arising as a result of somatopsychic and psychosomatic processes.

Relationship between balance system function and agoraphobic avoidance.

There is a striking similarity between the situations avoided by people with agoraphobia and the environments which provoke disorientation in people with organic balance disorders. This study investigated the possibility that agoraphobia might be linked to balance system dysfunction by comparing the results of balance system tests in 36 people with symptoms of panic and agoraphobia and 20 normal controls. A traditional battery of audiovestibular tests was supplemented with moving platform posturography, which assesses the postural instability induced by disorienting perceptual conditions. Subjects also completed questionnaire measures of somatic symptoms of dizziness and anxiety, agoraphobic cognitions, avoidance behaviour and state anxiety. Over 60% of the Ss with symptoms of panic and agoraphobia were destabilised by the disorienting perceptual conditions, compared with just 10% of the normal controls. Postural instability was strongly related to reported agoraphobic avoidance (r = 0.63, P < 0.01), even after controlling for symptoms, anxiety and agoraphobic cognitions. In our discussion we consider alternative interpretations of these findings, future directions for research, and implications for therapy.

Prevalence and presentation of dizziness in a general practice community sample of working age people.

BACKGROUND: Dizziness is known to be a common, handicapping condition in the elderly, and a strong association between dizziness and anxiety disorders has been observed in hospital samples. However, little is known about the prevalence of dizziness among people of working age in the community and its implications for psychosocial functioning and general practice consultation and treatment. AIM: To determine the prevalence of dizziness, giddiness, vertigo, and unsteadiness, and associations with disability and handicap, symptoms of panic and agoraphobia, and general practice consultation and treatment. METHOD: Postal questionnaires were completed by 2064 people aged 18-64 years randomly sampled from the patient lists of four London practices. Validated survey items were used to assess symptoms, panic and agoraphobia, levels of occupational disability and handicap, and general practice consultation and treatment. RESULTS: More than one in five responders (n = 480) had experienced dizziness during the past month; nearly half of these (n = 225) reported some degree of handicap and 30% had been dizzy for more than five years. Almost half (n = 221) of those with dizziness also reported anxiety and/or avoidance behaviour. Multiple physical and psychological symptoms were associated with higher levels of handicap. Only one in four of the 225 dizzy responders reporting some degree of handicap had received any form of treatment. CONCLUSION: Dizziness is a common, chronic, and often untreated symptom in people aged 18-65 years, associated with extensive handicap and psychological morbidity.

Benefits and challenges of newborn hearing screening for developing countries.

The late detection of permanent congenital and early-onset hearing loss (PCEHL) often has severe effects on linguistic, speech, cognitive and educational development in affected children. Since newborn hearing screening (NHS) allows most PCEHL to be detected early enough for optimal intervention, the prospects of its introduction in the developing world are reviewed in this paper. It is observed that a simple generalisation on the feasibility of NHS for the developing countries seems inappropriate in view of the diversities in the health and socio-economic status of these countries and the recent favourable reports of universal newborn hearing screening from the region. NHS empowers parents to make timely choices that will allow their hearing impaired children to be given a good start in life and be fully integrated into the wider community. It also compels attention towards the development of essential hearing healthcare services, besides the specific documented benefits. Existing child-healthcare structures such as the expanded programme on immunisation (EPI), baby friendly hospital initiatives (BFHI) and integrated management of childhood illness (IMCI) provide opportunities for the introduction of some form of NHS in many of these countries where routine or systematic childhood hearing screening does not exist. Limited funding, manpower shortages, inadequate support services, low public awareness and the uncertainty regarding the commitment from healthcare practitioners may present some challenges but these are not insurmountable. Pilot studies are necessary in each country to provide empirical data that will guide healthcare providers who wish to introduce such a programme at any level of healthcare delivery.

Neuro-otological function in X-linked hearing loss: a multipedigree assessment and correlation with other clinical parameters.

Auditory and vestibular investigations were carried out in 19 affected men and 13 obligate female carriers of 7 pedigrees with nonsyndromic hearing loss segregating as an X-linked trait. In addition, high resolution computerised tomographic scanning was carried out in 24 affected males and 12 obligate female carriers. The neuro-otological results confirm that non syndromic X-linked hearing loss is a clinically heterogeneous condition, but radiological assessment of the cochlea revealed two distinct groups: a normal group, and an abnormal group characterised by a bulbous internal auditory meatus, a dilated facial nerve canal and incomplete separation of the basal coil of the cochlea from the internal auditory meatus. Within a given pedigree there was marked consistency of the presence or absence of the CT scan abnormality in the affected males. One third of the obligate female carriers of the radiologically abnormal pedigrees were shown to have a similar abnormal finding, but as two thirds were normal, radiological examination did not predict carrier status. In the affected men, pure tone audiometric data did not correlate with the radiological abnormality, whereas vestibular function was strikingly correlated, being normal in all but one case in pedigrees with normal radiology and absent, or grossly impaired, in the pedigrees with abnormal radiology. Neuro-otological abnormalities were documented in approximately two thirds of the obligate female carriers, but were insufficiently frequent in occurrence or specific in type to be of predictive value.

Mechanisms of hearing loss in acoustic neuroma: an otoacoustic emission study.

Evoked otoacoustic emissions (EOAE) are active mechanical responses from the cochlea which provide information about the integrity of the preneural cochlear receptor mechanisms. It may be hypothesised, therefore, that if a hearing impairment is neural in origin, normal EOAEs may be obtained from the cochlea, which, although dissociated, is functioning normally. This study examined the status of the cochlea with EOAE in patients with cochlear (Meniere's disease) and neural (surgically proven acoustic neuroma) disease. In patients with presumed cochlear lesions, no emissions were present with mean hearing worse than 40 dB across a frequency range of 0.5 to 4 kHz. Similarly, an EOAE was not present in any of the 26 acoustic neuroma patients studied when the average (0.5 to 4 kHz) hearing was greater than 40 dB. We conclude that dissociation of the cochlea in patients with acoustic neuroma appears to be rare and, in fact, cochlear involvement occurs in most cases. Possible mechanisms responsible for the effect on the cochlea in this group include degenerative changes due to chronic partial obstruction of the blood supply by the tumour, biochemical alterations in the inner ear fluids, loss of efferent control of active mechanical tuning, and hair cell degeneration secondary to neuronal loss in the eighth nerve.

Latency of contralateral sound-evoked auditory efferent suppression of otoacoustic emissions.

The suppression of transiently evoked otoacoustic emissions by contralateral sound stimulation is thought to occur as a result of the action of the efferent pathway from the superior olivary complex to the cochlea via the medial olivo-cochlear neurons. The purpose of this study was to determine the time taken for this pathway to activate the suppressive mechanism in response to contralateral sound in normal human subjects. The time for onset of suppression was found to be between 7 and 20 ms.

Electrophoretic separation and identification of perilymph proteins in cases of acoustic neuroma.

Previous studies of perilymph proteins have emphasised the difficulty of obtaining samples free of blood or serum proteins. The present investigation has established a method of polyacrylamide gel electrophoresis, which enables contaminated specimens to be readily identified and therefore discarded. Analysis of uncontaminated samples has confirmed the presence of an elevated perilymph protein in cases of acoustic neurinomata. Perilymph proteins have been separated and identified and although no characteristic pattern of proteins associated with acoustic neurinomata has emerged, further work should be undertaken to establish the site of origin of perilymph proteins and the pattern of abnormalities to be expected in pathological processes.