A Portrait of Menière's Disease Using Contemporary Hearing and Balance Tests.

OBJECTIVE: Menière's disease (MD) is characterized by recurrent vertigo and fluctuating aural symptoms. Diagnosis is straightforward in typical presentations, but a proportion of patients present with atypical symptoms. Our aim is to profile the array of symptoms patients may initially present with and to analyze the vestibular and audiological test results of patients with a diagnosis of MD. DESIGN: A retrospective study of patient files. SETTING: A tertiary, neuro-otology clinic Royal Prince Alfred Hospital, Sydney, Australia. METHOD: We identified 375 patients. Their history, examination, vestibular-evoked myogenic potentials (VEMP), video head-impulse test, canal-paresis on caloric testing, subjective visual horizontal (SVH), electrocochleography, ictal nystagmus, and audiometry were assessed. RESULTS: Atypical presenting symptoms were disequilibrium (n = 49), imbalance (n = 13), drop-attacks (n = 12), rocking vertigo (n = 2), and unexplained vomiting (n = 3), nonspontaneous vestibular symptoms in 21.6%, fluctuation of aural symptoms only (46%), and headaches (31.2%). Low velocity, interictal spontaneous-nystagmus in 13.3% and persistent positional-nystagmus in 12.5%. Nystagmus recorded ictally in 90 patients was mostly horizontal (93%) and of high velocity (48 ±â€Š34°/s). Testing yielded abnormal caloric responses in 69.6% and abnormal video head impulse test 12.7%. Air-conducted cervical VEMPs were abnormal in 32.2% (mean asymmetry ratio [AR] 30.2 ±â€Š46.5%) and bone-conducted ocular VEMPs abnormal in 8.8% (AR 11.2 ±â€Š26.8%). Abnormal interictal SVH was in 30.6%, (ipsiversive n = 46 and contraversive n = 19). Mean pure-tone averages 50 dB ±â€Š23.5 and 20 dB ±â€Š13 for affected and unaffected ears. CONCLUSION: Menière's disease has a distinctive history, but atypical presentations with normal vestibular function and hearing are a diagnostic challenge delaying treatment initiation.

Meniere's Disease.

This article reviews 3 aspects of Meniere's disease (MD), which have been recently revisited: namely, the pathologic mechanism causing the attacks of vertigo, the clinical diagnosis, and the medical and surgical treatments. The characteristic attacks of vertigo are unlikely to be due to membrane ruptures, so a hypothesis that the vertigo is caused by a volume of endolymph shifting suddenly from the cochlea into the pars superior is suggested. The definite diagnosis according to the American Academy of Otolaryngology HNS 1995 criteria [13] failed to exclude vestibular migraine sufficiently and a revision in 2015 [14] has partly addressed this problem but another method which stresses the interaction of the cochlear and vestibular symptoms is described. The treatment of MD has been updated, providing evidence for each popular therapy. Newer treatments using intratympanic medications including steroid solutions and gentamicin are discussed. Finally, the role of cochlear implants is mentioned.

Cochlear Implant Outcomes in Cochlea Nerve Aplasia and Hypoplasia.

OBJECTIVE: To assess cochlear implant (CI) outcomes, and factors affecting outcomes, for children with aplasia/ hypoplasia of the cochlea nerve. We also developed a new grading system for the nerves of the internal auditory meatus (IAM) and cochlea nerve classification. STUDY DESIGN: Retrospective patient review. SETTING: Tertiary referral hospital and cochlear implant program. PATIENTS: Children 0 to 16 years inclusive with a CI who had absent/hypoplastic cochlea nerve on magnetic resonance imaging (MRI). INTERVENTION: Cochlear implant. MAIN OUTCOME MEASURES: MRI, trans-tympanic electrical auditory brainstem response, intraoperative electrical auditory brainstem response, Neural Response Telemetry, Categories of Auditory Perception score, Main mode of communication. RESULTS: Fifty CI recipients (26 males and 24 females) were identified, 21 had bilateral CIs, 27 had developmental delay. MRI showed cochlea nerve aplasia in 64 ears, hypoplasia in 25 ears, and a normal nerve in 11 ears. Main mode of communication was analyzed for 41 children: 21 (51%) used verbal language (15 speech alone, 5 speech plus some sign, 1 bilingual in speech and sign), and 20 (49%) used sign language (10 sign alone, 9 sign plus some speech, 1 tactile sign). Seventy-three percent of children used some verbal language. Cochlea nerve aplasia/ hypoplasia and developmental delay were both significant factors affecting main mode of communication. Categories of Auditory Performance scores were available for 59 CI ears; 47% with CN Aplasia (IAM nerve grades 0-III) and 89% with CN hypoplasia (IAM nerve grade IV) achieved Categories of Auditory Performance scores of 5 to 7 (some verbal understanding) (p = 0.003). CONCLUSION: Our results are encouraging and useful when counselling families regarding the likelihood of language outcomes and auditory understanding.

CHARGE syndrome and Cochlear implantation: difficulties and outcomes in the paediatric population.

OBJECTIVES: CHARGE syndrome is a complex cluster of congenital abnormalities, these children may have absent or hypoplastic auditory nerves. Our objective was to assess preoperative factors and outcomes for paediatric cochlear implant recipients with CHARGE syndrome, to enable better surgical preparation and family counselling. METHODS: The Sydney Cochlear Implant Centre database was searched for children with CHARGE syndrome who had received a cochlear implant at ages 16 and less. Data were collected regarding clinical history; hearing assessments; MRI and CT scan findings; preoperative transtympanic electrical Auditory Brainstem Response (ABR); intraoperative findings and intraoperative electrical ABR and Neural Response Telemetry; and language outcomes in terms of main language used and Categories of Auditory Performance scores (0-7 ranking). RESULTS: Ten children were identified. All seven prelingual profoundly deaf children with CHARGE syndrome had hypoplastic or absent auditory nerves bilaterally on MRI scans. Middle ear anatomy was often abnormal, affecting surgical landmarks and making identification of the cochlea very difficult in some cases. Three cases required repeated surgery to obtain successful cochlear implant insertion, one under CT scan image guided technique. All seven children used sign language, or simpler gestures, as their main mode of communication. Two children of of these children, who were implanted early, also attained some spoken language. CAP scores ranged from 0 to 6. The three children with CHARGE syndrome and progressive sensorineural hearing loss had a normal auditory nerve in at least one ear on MRI scans. All had preoperative verbal language, with CAP scores of 6, and continued with CAP scores of 6 following receipt of the cochlear implant. CONCLUSION: Children with CHARGE and congenital profound hearing loss all had hypoplasia or absent auditory nerves, affecting their outcomes with cochlear implants. They often had markedly abnormal middle ear anatomy and CT image guided surgery can be helpful. These children should be offered a bilingual early intervention approach, using sign language and verbal language, to ensure best language outcomes. Children with CHARGE syndrome and progressive profound hearing loss did well with cochlear implants and continue to be able to use verbal language.

Pediatric cochlear implantation: associated with minimal postoperative pain and dizziness.

OBJECTIVE: To prospectively document the surgical pain, assessing analgesia use as a proxy, and postoperative dizziness in children over the first week after cochlear implantation. STUDY DESIGN: Prospective. SETTING: Tertiary referral hospital and cochlear implant program. PATIENTS: Children aged 0 to 16 years inclusive undergoing cochlear implant surgery, who returned to see the primary surgeon for the postoperative 1-week follow-up appointment. INTERVENTIONS: One-week postoperative collection of data via direct questioning of parents and children. MAIN OUTCOME MEASURES: Analgesia use, duration of analgesia use and dizziness (nil, slight, or moderate), type of surgery, and radiologic findings. RESULTS: Data were available for 61 of 98 children aged 5 months to 15 years. Children underwent first side implant (n = 27), sequential second side implant (n = 15), bilateral simultaneous (n = 16), and explant reimplantation (n = 3). On average, children used paracetamol for only 1.9 days after discharge from the hospital. Longer average paracetamol use was associated with bilateral simultaneous surgery (3.3 d after discharge from the hospital) and also the younger age group of 0 to 12 months (3.2 d). Slight dizziness was reported by 8% of all children at 1 week postsurgery.No child had marked dizziness or unsteadiness. Four children had large vestibular aqueducts on radiology scans, two (50%) of these children has slight unsteadiness at 1 week postoperatively. CONCLUSION: Our study shows cochlear implant surgery is well tolerated by children. This information enables better counseling of families and children considering cochlear implantation.

Impedance, neural response telemetry, and speech perception outcomes after reimplantation of cochlear implants in children.

OBJECTIVE: To compare mean impedance levels, neural response telemetry (NRT), and auditory perception after initial and explant-reimplant pediatric cochlear implants. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral hospital and cochlear implant program. PATIENTS: Children 0 to 16 years inclusive who have undergone explant-reimplant of their cochlear implant. INTERVENTION: Impedance levels, NRT, and speech perception performance. MAIN OUTCOME MEASURES: Impedance, NRT, and auditory perception at switch on, 3 months, 12 months, 3 years, and 5 years after initial cochlear implant and reimplantation. RESULTS: The explant-reimplant group receiving Cochlear contour array had significantly (p < 0.001) raised impedance at switch on, 3 months, 12 months, and 3 years, compared with their initial implant. The explant-reimplant group receiving Cochlear straight array had marginally significant (p = 0.045) raised impedance at switch on, 3 months, 12 months, and 3 and 5 years. Infection was associated with greater increases in impedance in the reimplant Contour group. NRT was increased in the explant-reimplant group but not significantly (p = 0.06). Auditory perception returned to preexplant levels within 6 months in 61% of children. CONCLUSION: Impedance is higher after explant-reimplant and remains increased for years after explant-reimplant with Cochlear contour and to a lesser degree the straight array device.

Cochlear implants and magnetic resonance scans: A case report and review.

OBJECTIVE AND IMPORTANCE: Traditionally, magnetic resonance imaging (MRI) was contraindicated for patients with cochlear implants (CIs), due to concern about device displacement, overheating of the device or tissues, or direct damage to the device electrode. In addition, image artifact from the device magnet gave poor imaging information in the cranial and upper cervical spine region. Today, MRI is increasingly required in patients who have undergone cochlear implantation, and CI design and MRI protocols have therefore changed to allow implanted patients to safely enter the MRI field, in some cases without removal of the CI internal magnet. CLINICAL PRESENTATION: We present a patient with bilateral CIs who required MRI to investigate new neurological symptoms. Despite tight head bandaging applied according to our protocol, MRI at 1.5 T led to bilateral skin reactions and displacement of the magnet on the left. Both magnets were subsequently removed to allow the skin reactions to settle and for further imaging without artifact. The functioning of the patient's implants was not affected. CONCLUSION: The final decision to recommend that a patient with a CI undergoes MRI, with or without removal of the internal magnet, requires close cooperation between the CI team, the physician requiring the scan, and the radiology team involved in the patient's care. The case study we present highlights the need for patients to be fully informed of the risks involved.

Pediatric cochlear implants: additional disabilities prevalence, risk factors, and effect on language outcomes.

OBJECTIVE: To determine the prevalence of additional disabilities in a pediatric cochlear population, to identify medical and radiologic conditions associated with additional disabilities, and to identify the effect of additional disabilities on speech perception and language at 12 months postoperatively. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center and cochlear implant program. PATIENTS: Records were reviewed for children 0 to 16 years old inclusive, who had cochlear implant-related operations over a 12-month period. INTERVENTIONS: Diagnostic and rehabilitative. MAIN OUTCOME MEASURES: Additional disabilities prevalence; medical history and radiologic abnormalities; and the effect on Categories of Auditory Performance (CAP) score at 12 months postoperatively. RESULTS: Eighty-eight children having 96 operations were identified. The overall prevalence of additional disabilities (including developmental delay, cerebral palsy, visual impairment, autism and attention deficit disorder) was 33%. The main conditions associated with additional disabilities were syndromes and chromosomal abnormalities (87%), jaundice (86%), prematurity (62%), cytomegalovirus (60%), and inner ear abnormalities including cochlea nerve hypoplasia or aplasia (75%) and semicircular canal anomalies (56%). At 12 months postoperatively, almost all (96%) of the children without additional disabilities had a CAP score of 5 or greater (speech), compared with 52% of children with additional disabilities. Children with developmental delay had a median CAP score of 4, at 12 months compared with 6 for those without developmental delay. CONCLUSION: Additional disabilities are prevalent in approximately a third of pediatric cochlear implant patients. Additional disabilities significantly affect the outcomes of cochlear implants.

Augmented ocular vestibular evoked myogenic potentials to air-conducted sound in large vestibular aqueduct syndrome.

OBJECTIVE: To demonstrate the value of recording air-conducted ocular Vestibular Evoked Myogenic Potentials (oVEMP) in a patient with bilaterally enlarged vestibular aqueducts. DESIGN: Cervical VEMP and oVEMP were recorded from a patient presenting with bilateral hearing loss and imbalance, attributable to large vestibular aqueduct syndrome. The stimuli were air-conducted tone bursts at octave frequencies from 250 to 2000 Hz. Amplitudes and thresholds were measured and compared with the normal response range of 32 healthy control subjects. RESULTS: oVEMP reflexes demonstrated pathologically increased amplitudes and reduced thresholds for low-frequency tone bursts. Cervical VEMP amplitudes and thresholds were within normal limits for both ears across all frequencies of stimulation. CONCLUSIONS: This study is the first to describe the augmentation of AC oVEMPs in an adult with large vestibular aqueduct syndrome.

Assessment of intracochlear trauma caused by the insertion of a new straight research array.

OBJECTIVE: To assess the degree of intracochlear trauma using the Cochlear™ Straight Research Array (SRA). This electrode has recently been released by Cochlear™ on the CI422 implant. BACKGROUND: Electroacoustic stimulation (EAS) enables recipients to benefit from cochlear implantation while retaining their natural low-frequency hearing. A disadvantage of short EAS electrodes is that short electrodes provide limited low-frequency stimulation. Thus, loss of the residual hearing may require reimplantation with a longer electrode. In order to overcome this problem, the slim diameter SRA with increased length (20-25 mm) has been designed to provide a deeper, yet non-traumatic insertion. METHODS: Two insertion studies into temporal bones were undertaken. The first involved dissection of the cochlea to gain a view into the scala vestibuli and insertion of the SRA and control electrodes with a microactuator for a surgeon-independent yet controlled insertion. High-speed photography was used to record data. The second study involved a high-resolution X-ray microcomputed tomography (microCT) study to assess electrode placement and tissue preservation in surgeon-implanted bones. RESULTS: The SRA had a smooth insertion trajectory. The average angular insertion depth was 383° when inserted until resistance was encountered, and 355° if inserted to a predetermined mark for EAS use. In addition, microCT data showed that this caused no significant trauma or distortion of the basilar membrane up to 20 mms depth. CONCLUSION: Temporal bone studies show that the SRA appears to cause no intracochlear trauma if used as an EAS electrode up to 20 mm depth of insertion.

Intra-individual assessment of speech and music perception in cochlear implant users with contralateral Cochlear™ and MED-EL™ systems.

CONCLUSION: Whilst objective testing on music perception showed no individual differences between cochlear implant (CI) devices, subjective music perception was found to be superior with the MED-EL device in the majority of cases evaluated. OBJECTIVE: To compare speech and music perception through two different CI systems in the same individuals. METHODS: Six post-lingually deaf patients, who had been implanted with a Cochlear™ Nucleus(®) device in one ear and a MED-EL SONATATI(100) on the contralateral side were evaluated. One subject was excluded from group analysis because of significant differences in performance between ears. Subjects completed a questionnaire designed to assess implant users' listening habits. Subjective assessments of each subject were made for comparison of speech and music perception with each system and preferences of system. The subjects consecutively used each system with the contralateral device turned off, and were objectively assessed for specific musical skills. Speech perception in quiet and in noise was tested. RESULTS: For all objective tests of music discrimination and speech perception in noise, there were no statistically significant differences between MED-EL and Cochlear CI systems. Subjectively, four subjects thought their MED-EL device was better than their Cochlear device for music appreciation. Four thought that music sounded more natural, less tinny and more reverberant with their MED-EL CI than with their Cochlear CI. One subject rated all these to be equal.

On the differential diagnosis of Ménière's disease using low-frequency acoustic biasing of the 2f1-f2 DPOAE.

We have cyclically suppressed the 2f1-f2 distortion product otoacoustic emission (DPOAE) with low-frequency tones (17-97 Hz) as a way of differentially diagnosing the endolymphatic hydrops assumed to be associated with Ménière's syndrome. Round-window electrocochleography (ECochG) was performed in subjects with sensorineural hearing loss (SNHL) on the day of DPOAE testing, and from which the amplitude of the summating potential (SP) was measured, to support the diagnosis of Ménière's syndrome based on symptoms. To summarize and compare the cyclic patterns of DPOAE modulation in these groups we have used the simplest model of DPOAE generation and modulation, by assuming that the DPOAEs were generated by a 1st-order Boltzmann nonlinearity so that the magnitude of the 2f1-f2 DPOAE resembled the 3rd derivative of the Boltzmann function. We have also assumed that the modulation of the DPOAEs by the low-frequency tones was simply due to a sinusoidal change in the operating point on the Boltzmann nonlinearity. We have found the cyclic DPOAE modulation to be different in subjects with Ménière's syndrome (n = 16) when compared to the patterns in normal subjects (n = 16) and in other control subjects with non-Ménière's SNHL and/or vestibular disorders (n = 13). The DPOAEs of normal and non-Ménière's ears were suppressed more during negative ear canal pressure than during positive ear canal pressure. By contrast, DPOAE modulation in Ménière's ears with abnormal ECochG was greatest during positive ear canal pressures. This test may provide a tool for diagnosing Ménière's in the early stages, and might be used to investigate the pathological mechanism underlying the hearing symptoms of this syndrome.

The vestibular evoked-potential profile of Ménière's disease.

OBJECTIVE: To define the ocular and cervical vestibular evoked myogenic potential (oVEMP and cVEMP) profile in Ménière's Disease (MD), we studied air-conducted (AC) sound and bone-conducted vibration (BCV)-evoked responses in 77 patients and 35 controls. METHODS: oVEMPs were recorded from unrectified infra-orbital surface electromyography (EMG) during upward gaze. cVEMPs were recorded from rectified and unrectified sternocleidomastoid EMG during head elevation against gravity. Responses to AC clicks delivered via headphones and BC forehead taps delivered with a mini-shaker (bone-conduction vibrator) and a triggered tendon-hammer were recorded. RESULTS: In clinically definite unilateral MD (n=60), the prevalence of unilateral VEMP abnormalities was 50.0%, 10.2% and 11.9% for click, minitap and tendon-hammer evoked oVEMPs, 40.0%, 22.8% and 10.7% for click, minitap and tendon-hammer evoked cVEMPs. The most commonly observed profile was abnormality to AC stimulation alone (33.3%), followed by abnormalities to both AC and BCV stimuli (26.7%). Isolated abnormalities to BCV stimuli were rare (5%) and limited to the minitap cVEMP. The prevalence of abnormalities for each of the AC VEMPs was significantly higher than for any one BCV VEMP. For click cVEMP, click oVEMP and minitap cVEMP, average Reflex Asymmetry Ratios (AR) were significantly higher in MD compared with controls. Test results for AC cVEMP, AC oVEMP, minitap cVEMP and caloric asymmetry were significantly correlated with hearing loss. CONCLUSIONS: Predominance of abnormalities in oVEMP and cVEMP responses to AC sound is characteristic of MD and indicative of saccular involvement. SIGNIFICANCE: This pattern of VEMP abnormalities may enable separation of Ménière's disease from other peripheral vestibulopathies.

Hypothetical mechanism for vertigo in Meniere's disease.

Past theories that have been proposed to account for the attacks of vertigo during the course of Meniere disease are reviewed. In the past, vascular theories and theories of perilymph and endolymph mixing due to ruptures or leakages were proposed. Recent research concerning the basic mechanisms of the inner ear anatomy and function cast doubt on these theories. The anatomy, physiology, and pathophysiology of the inner ear, and in particular of the endolymphatic sac and endolymphatic duct are reviewed. Recent studies suggest that in people the endolymph ionic content is replenished without any flow of fluid and that longitudinal endolymph flow only occurs in response to volume excess. Furthermore audiological and electrophysiological studies have revealed little or no change in the cochlear function during episodes of vertigo. The longitudinal drainage theory attempts to encompass the recent research findings. The theory hypothesizes that endolymph draining too rapidly from the cochlear duct (pars inferior) causes attacks of vertigo. The endolymph overfills the endolymphatic sinus and overflows into the utricle (pars superior), stretching the cristae of the semicircular canals, causing the attacks of vertigo.

Changes in audiometric thresholds before, during and after attacks of vertigo associated with Meniere's syndrome.

CONCLUSION: No significant changes in hearing thresholds were observed during vertigo attacks associated with Meniere's disease. OBJECTIVES: To determine if the hearing alters during the period of the attacks of vertigo in Meniere's disease. PATIENTS AND METHODS: The study group consisted of patients who had a clinical diagnosis of definite Meniere's syndrome according to the AAOOHNS criteria, a score on the Gibson scale of 7 or over and an enhanced negative summating potential on transtympanic electrocochleography. These patients were supplied with a programmable hearing aid and a portable programmer that allowed them to measure their own hearing in situ. They were asked to measure their audiometric thresholds daily and if possible during the attacks of vertigo. RESULTS: Six of the patients were able to measure their hearing during attacks of vertigo and their hearing thresholds obtained before, during and after the vertigo attacks were compared. Five of six subjects showed <10 dBHL change in the hearing levels at all tested audiometric frequencies before, during and after the attacks of vertigo. One subject had a probable change in threshold before the attack but not during the attack of vertigo.

Grading of endolymphatic hydrops using magnetic resonance imaging.

CONCLUSION: Grading of endolymphatic hydrops in the vestibule and the cochlea using magnetic resonance imaging (MRI) is proposed (2008 Nagoya scale). OBJECTIVE: To standardize the evaluation of endolymphatic hydrops in both the vestibule and the cochlea using MRI. PATIENTS AND METHODS: The endolymphatic space was evaluated after intratympanic gadolinium injection using three-dimensional fluid attenuated (3D-FLAIR) MRI and three-dimensional real inversion recovery (3D-real IR) MRI. RESULTS: A simple three-stage grading system was acceptable for hydrops in both the vestibule and the cochlea: none, mild, and significant. In the vestibule, the grading was determined by the ratio of the area of endolymphatic space to the vestibular fluid space (sum of the endolymphatic and perilymphatic spaces). Patients with no hydrops have a ratio of one-third or less, those with mild hydrops have between one-third and a half, and those with significant hydrops have a ratio of more than 50%. In the cochlea, patients classified as having no hydrops show no displacement of Reissner's membrane; those with mild hydrops show displacement of Reissner's membrane but the area of the endolymphatic space does not exceed the area of the scala vestibuli; and in those with significant hydrops the area of the endolymphatic space exceeds the area of the scala vestibuli.

A comparison of two methods of using transtympanic electrocochleography for the diagnosis of Meniere's disease: click summating potential/action potential ratio measurements and tone burst summating potential measurements.

CONCLUSION: Transtympanic electrocochleography (TT ECochG) is helpful for the confirmation of Meniere's disease using tone burst stimuli to measure the amplitude of the frequency specific summating potentials (SP) but not when using the click evoked summating potential versus action potential ratio (SP/AP). OBJECTIVES: To evaluate the effectiveness of TT ECochG as a means of confirming the clinical diagnosis of Meniere's disease. PATIENTS AND METHODS: A total of 2,717 patients were referred for TT ECochG between August 1998 and September 2008. Each patient was assessed prospectively on clinical grounds according to the AAOHNS criteria and a scale devised by the author. A Meniere's group and a non-Meniere's group were determined and the TT ECochG results were compared between the groups that had similar hearing levels for the particular stimulus employed. RESULTS: Click SP/AP measurements did not significantly differentiate between populations of Meniere's ears and non-Meniere's ears. Tone burst SP amplitude measurements were significantly different between the populations, especially using frequencies at 500 Hz, 1 kHz, and 2 kHz.

The use of intra-operative electrical auditory brainstem responses to predict the speech perception outcome after cochlear implantation.

Electrically evoked auditory brainstem responses (EABR) were obtained intra-operatively from children receiving full insertion of Cochlear CI24 implant. The EABR waveform was quantified according to the presence or absence of waves (eII-eV). Each trace was scored from 0-3 providing a maximum score for all 22 electrodes of 66 in the monopolar mode. Speech perception scores were measured after one year in 245 children and after two years of cochlear implant use in 148 children. Significant differences in the EABR waveforms were found between those recipients who achieved scores of 4 or greater on the Melbourne scale and those recipients who only had a modest outcome. After two years, the outcome showed even greater differences. The group of 103 children who had outcomes of 4 or greater at one year improved from a mean score of 4.7 to 5.7. The group of 45 children who had outcomes of 3 or less at one year only improved from a mean score of 2.9 to 3.15. In this latter group, only four children showed any significant improvement.

The association of codeine, macrocytosis and bilateral sudden or rapidly progressive profound sensorineural deafness.

CONCLUSIONS: Codeine shows a similar association with profound deafness to other opiates. Good cochlear implant outcomes suggest a sensory disorder. Although macrocytosis could be due to confounding factors, the lack of other consistent findings may signify a vascular pathology. OBJECTIVES: To describe a series of patients identified as codeine users after referral for cochlear implantation. PATIENTS AND METHODS: This was a retrospective case series review. Patients were identified by the senior audiologist. Information regarding mode of onset of deafness, past medical history, drug and alcohol history, investigations and audiological outcomes following cochlear implantation was collected from hospital records and patient questionnaires. RESULTS: Ten patients were included in the study. All patients had taken codeine phosphate and paracetamol in combination for several years, usually at greater than recommended daily dose. All patients presented with sudden or rapidly progressive bilateral deafness. All patients had a significant macrocytosis at the time of deafness (mean cell volume (MCV): mean 115 fL; range 105-132 fL). No other investigation was consistently abnormal. Four patients had a history of alcoholism. Seven patients had abnormal liver function tests. Patients usually performed well with cochlear implants (CUNY sentence scores without lip reading >90% in 9 of 10 patients).

Frequency-specific electrocochleography indicates that presynaptic and postsynaptic mechanisms of auditory neuropathy exist.

OBJECTIVES: The physiological mechanisms underlying auditory neuropathy (AN) remain unclear and it is likely that the multiple disruptions are classified under the broadly defined term. Cochlear implantation is being more widely used in this population to bypass the suspected site-of-lesion although a number of cases have been identified within the Sydney Cochlear Implant Centre where this management strategy has been unsuccessful. It is likely that this relates to the different physiological mechanisms underlying AN. DESIGN: To investigate the site-of-lesion in AN, frequency-specific round window electrocochleography (ECochG) was used to assess local hair-cell, dendritic, and axonal currents generated within the cochlea in 14 subjects with AN and compared with responses from two normally hearing subjects. ECochG results were then compared with electrically evoked auditory brain stem response (EABR) measured after cochlear implantation. RESULTS: The results of this study demonstrate that two dominant patterns of ECochG waveforms (produced by a high-frequency alternating tone burst) can be identified in this population of AN subjects: (a) gross waveform showing a prolonged summating potential (SP) latency that, in most cases, is followed by a small compound action potential; and (b) gross waveform showing a normal latency SP waveform followed by a broad negative potential [assumed to reflect the dendritic potential (DP) identified in anaesthetized guinea-pigs]. This study demonstrates that in most subjects (n = 7) with a prolonged latency SP but no DP, normal morphology EABR waveforms were elicited for all electrode channels. On the other hand, all subjects (n = 7) who showed a normal latency SP followed by a broad negative DP, showed EABR waveforms that were absent or having poor wave V morphology. The authors' interpretation of this is that ECochG results may provide a classification of AN into pre- and postsynaptic lesions. CONCLUSIONS: We suggest that a presynaptic and postsynaptic type of AN exist that may have implications for the fitting of cochlear implants.