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.

Effects of chronic noise exposure on speech-in-noise perception in the presence of normal audiometry.

OBJECTIVE: To assess auditory processing in noise-exposed subjects with normal audiograms and compare the findings with those of non-noise-exposed normal controls. METHODS: Ten noise-exposed Royal Air Force aircrew pilots were compared with 10 Royal Air Force administrators who had no history of noise exposure. Participants were matched in terms of age and sex. The subjects were assessed in terms of: pure tone audiometry, transient evoked otoacoustic emissions, suppression of transient evoked otoacoustic emissions in contralateral noise and auditory processing task performance (i.e. masking, frequency discrimination, auditory attention and speech-in-noise). RESULTS: All subjects had normal pure tone audiometry and transient evoked otoacoustic emissions amplitudes in both ears. The noise-exposed aircrew had similar pure tone audiometry thresholds to controls, but right ear transient evoked otoacoustic emissions were larger and speech-in-noise thresholds were elevated in the noise-exposed subjects compared to controls. CONCLUSION: The finding of poorer speech-in-noise perception may reflect noise-related impairment of auditory processing in retrocochlear pathways. Audiometry may not detect early, significant noise-induced hearing impairment.

The effect of virtual reality on visual vertigo symptoms in patients with peripheral vestibular dysfunction: a pilot study.

UNLABELLED: Individuals with vestibular dysfunction may experience visual vertigo (VV), in which symptoms are provoked or exacerbated by excessive or disorientating visual stimuli (e.g. supermarkets). VV can significantly improve when customized vestibular rehabilitation exercises are combined with exposure to optokinetic stimuli. Virtual reality (VR), which immerses patients in realistic, visually challenging environments, has also been suggested as an adjunct to VR to improve VV symptoms. This pilot study compared the responses of sixteen patients with unilateral peripheral vestibular disorder randomly allocated to a VR regime incorporating exposure to a static (Group S) or dynamic (Group D) VR environment. Participants practiced vestibular exercises, twice weekly for four weeks, inside a static (Group S) or dynamic (Group D) virtual crowded square environment, presented in an immersive projection theatre (IPT), and received a vestibular exercise program to practice on days not attending clinic. A third Group D1 completed both the static and dynamic VR training. Treatment response was assessed with the Dynamic Gait Index and questionnaires concerning symptom triggers and psychological state. At final assessment, significant between-group differences were noted between Groups D (p=0.001) and D1 (p=0.03) compared to Group S for VV symptoms with the former two showing a significant 59.2% and 25.8% improvement respectively compared to 1.6% for the latter. Depression scores improved only for Group S (p=0.01) while a trend towards significance was noted for Group D regarding anxiety scores (p=0.07). CONCLUSION: Exposure to dynamic VR environments should be considered as a useful adjunct to vestibular rehabilitation programs for patients with peripheral vestibular disorders and VV symptoms.

The Tullio phenomenon: a neurologically neglected presentation.

The Tullio phenomenon refers to sound-induced disequilibrium or oscillopsia. Patients with this condition frequently present to neurologists, many of whom are unfamiliar with the condition and its diagnostic criteria. Indeed, due to the unusual nature of the symptoms patients are often misdiagnosed as having psychiatric disturbances. Tullio patients describe disequilibrium, auditory and visual symptoms, which are recurrent, brief, and often triggered by loud noises or middle ear pressure changes, e.g. the Valsalva manoeuvre. Many cases are associated with superior semicircular canal dehiscence (SCCD). Early work suggested that the presence of sound-induced torsional eye movements and visual field tilts were consequent upon a utricular-mediated ocular tilt reaction. However, more recent evidence from imaging and oculographic research, as well as data from our patient series indicates that these ocular abnormalities are usually the result of superior semicircular canal stimulation. The clinical history and a focussed examination are often sufficient to make the diagnosis, which can be confirmed with high resolution CT imaging of the temporal bones. In some patients, surgical occlusion or resurfacing of the affected canal can ameliorate symptoms and signs. The aim of this paper is two-fold: Firstly, to review the clinical features of the Tullio phenomenon, and secondly, to highlight our own observations in three cases with a new clinical syndrome consisting of Tullio's phenomenon with bilateral vestibular failure, a pure horizontal nystagmus in response to sound, and no evidence of canal dehiscence.

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.

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.

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.

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.

Clinical value of tone burst vestibular evoked myogenic potentials at threshold in acute and stable Ménière's disease.

INTRODUCTION: The objectives of this preliminary, prospective, cohort study were to ascertain the characteristics of vestibular evoked myogenic potentials at threshold levels in two groups of Ménière's disease patients - acute and stable - and to identify whether vestibular evoked myogenic potentials can provide any specific, objective information to distinguish acute from stable Ménière's disease. SUBJECTS AND METHODS: The study was based at a tertiary neuro-otology centre. Twenty adult patients who fulfilled the American Academy of Otolaryngology-Head and Neck Surgery criteria for Ménière's disease were divided into two groups: 11 patients with acute Ménière's disease and nine patients with stable Ménière's disease. Eighteen healthy adult volunteers served as controls. All subjects underwent vestibular evoked myogenic potential testing with ipsilateral, short tone burst stimuli at 500 Hz, as well as pure tone audiometry. The patients also underwent caloric testing. RESULTS: Vestibular evoked myogenic potentials were present in all controls, and were present in 65 per cent of patients but absent in 35 per cent. The mean absolute threshold (Tvestibular evoked myogenic potential) +/- standard deviation in normal controls was 116 +/- 7.7 dBSPL; this did not differ statistically from that in patients, nor did it differ between acute and stable Ménière's disease. The p13/n23 latencies at the threshold levels in the normal, acute and stable groups (mean +/- standard deviation) were respectively: 15 +/- 2.2 ms/23.0 +/- 2.5 ms; 15.7 +/- 0.9 ms/23.7 +/- 0.9 ms; and 15.3 +/- 2.0 ms/24.2 +/- 1.9 ms. The mean interaural amplitude difference ratio (IAD) +/- standard deviation was significantly higher in the stable group compared with the acute group (0.54 +/- 0.33 vs -0.15 +/- 0.22; p = 0.007) and with the controls (0.54 +/- 0.33 vs 0.1 +/- 0.22; p = 0.05). CONCLUSIONS: The parameter that best differentiated acute from stable Ménière's disease at threshold was the interaural amplitude difference ratio. Therefore, this parameter may be used to monitor the clinical course of Ménière's disease.

Ethical issues in screening for hearing impairment in newborns in developing countries.

Screening of newborns for permanent congenital or early-onset hearing impairment has emerged as an essential component of neonatal care in developed countries, following favourable outcomes from early intervention in the critical period for optimal speech and language development. Progress towards a similar programme in developing countries, where most of the world's children with hearing impairment reside, may be impeded by reservations about the available level of support services and the possible effect of the prevailing healthcare challenges. Ethical justification for the systematic introduction of screening programmes for hearing in newborns based on the limitations in current primary prevention strategies, lack of credible alternative early-detection strategies and the incentives for capacity-building for the requisite support services is examined.

Auditory temporal processing deficits in patients with insular stroke.

OBJECTIVE: To assess central auditory function in a series of patients with stroke of the insula and adjacent areas. METHODS: The authors recruited eight patients with stroke affecting the insula and adjacent areas and eight neurologically normal controls (matched to the patients for age, sex, handedness, and hearing thresholds). The lesion spared the adjacent auditory areas in three patients and included other auditory structures in five cases. The authors conducted pure-tone audiometry and tympanometry and a central auditory test battery, which included the dichotic digits, and three temporal tests, the duration pattern, frequency pattern, and gaps in noise tests. They collected information from the hospital notes on symptoms at presentation and neuropsychological assessment data during the acute phase. RESULTS: The central auditory tests gave normal results in all controls. The temporal tests gave abnormal results in all three cases in which other auditory areas were spared, as well as in the other five cases. Results of the gaps in noise test were abnormal contralaterally to the lesion in three and bilaterally in five cases. The central auditory deficits did not cosegregate with the presence of cognitive impairment during the acute stage. CONCLUSION: Insular lesions may affect central auditory function and, in particular, temporal resolution and sequencing, consistent with neuroimaging studies.

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.

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.

Infant hearing screening: route to informed choice.

The decision to participate in infant screening often rests with parents. Medical ethics require that parental decision is elicited from informed choice. Such a decision is influenced by the parental knowledge and attitude towards screening and a careful evaluation of these factors is essential in seeking informed consent for infant hearing screening.

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.

Progressive auditory neuropathy in patients with Leber's hereditary optic neuropathy.

OBJECTIVE: To investigate auditory neural involvement in patients with Leber's hereditary optic neuropathy (LHON). METHODS: Auditory assessment was undertaken in two patients with LHON. One was a 45 year old woman with Harding disease (multiple-sclerosis-like illness and positive 11778mtDNA mutation) and mild auditory symptoms, whose auditory function was monitored over five years. The other was a 59 year old man with positive 11778mtDNA mutation, who presented with a long standing progressive bilateral hearing loss, moderate on one side and severe to profound on the other. Standard pure tone audiometry, tympanometry, stapedial reflex threshold measurements, stapedial reflex decay, otoacoustic emissions with olivo-cochlear suppression, auditory brain stem responses, and vestibular function tests were undertaken. RESULTS: Both patients had good cochlear function, as judged by otoacoustic emissions (intact outer hair cells) and normal stapedial reflexes (intact inner hair cells). A brain stem lesion was excluded by negative findings on imaging, recordable stapedial reflex thresholds, and, in one of the patients, olivocochlear suppression of otoacoustic emissions. The deterioration of auditory function implied a progressive course in both cases. Vestibular function was unaffected. CONCLUSIONS: The findings are consistent with auditory neuropathy-a lesion of the cochlear nerve presenting with abnormal auditory brain stem responses and with normal inner hair cells and the cochlear nucleus (lower brain stem). The association of auditory neuropathy, or any other auditory dysfunction, with LHON has not been recognised previously. Further studies are necessary to establish whether this is a consistent finding.

Hearing loss in adult Refsum's disease.

Refsum's disease is characterized by defective peroxisomal alpha oxidation of phytanic acid, with clinical features that include retinitis pigmentosa, polyneuropathy, anosmia and hearing loss. Although hearing loss in Refsum's disease is common, there are few detailed assessments of the site of the abnormality. We examined the audiometric findings in patients with biochemically diagnosed Refsum's disease in order to assess the site of origin of the hearing loss. We found hearing loss, ranging from mild, predominantly high frequency to moderate degree, in seven out of nine patients with biochemically diagnosed adult Refsum's disease. In addition, we found evidence to suggest subtle auditory nerve involvement in six out of the seven patients with hearing loss and in one out of the two patients with a normal pure tone audiogram, on the basis of the ABR test results. We conclude that patients with Refsum's disease who report hearing difficulties should have full audiometric investigations in order to provide appropriate audiological rehabilitation.

Neuro-otological findings in Pendred syndrome.

Pendred syndrome is an autosomal recessive inherited disorder characterized by profound hearing impairment and inappropriate iodine release by the thyroid on perchlorate challenge. Thirty-three cases comprising members of 13 families and eight isolated cases were studied, with detailed audiological and vestibular investigation and computerized tomography. A uniform, profound, symmetrical sensorineural hearing loss was identified in all cases. Approximately one-third of the group reported progressive hearing impairment, in childhood or adolescence, associated with head injury, infection, or delayed secondary hydrops. Ninety per cent of the cases scanned showed dilated vestibular aqueducts, and all cases with progression of the hearing impairment demonstrated this structural abnormality. Approximately one-third of the cases had normal vestibular function, but a further third demonstrated a unilateral peripheral deficit, while the remaining third showed bilateral vestibular hypofunction. There was no intra-familial concordance of vestibular findings, and no correlation between vestibular abnormality and presence or absence of a dilated vestibular aqueduct, with or without a Mondini malformation. In older children and adults, Pendred syndrome was associated with a profound, symmetrical, sensorineural auditory impairment, and a variety of vestibular abnormalities, which are not uniform within families, or correlated with structural labyrinthine deformities.

Aetiology and clinical presentations of auditory processing disorders--a review.

Auditory processing disorders may have detrimental consequences on a child's life, if undiagnosed and untreated. We review causes of auditory processing disorders in order to raise clinical awareness. Auditory processing disorders may present against a background of neurological disease or developmental disorders, as well as in isolation. Clinicians need to be aware of potential causes and implications of auditory processing disorders.