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Biomedical subjects

S M Mason

Publications and source records attributed to S M Mason.

At least 19 recordsLinked to original sources
PubMed2006

Are these emergency department performance data real?

We have recently demonstrated that the distribution of total time spent by patients in emergency departments (EDs) in England shows a peak immediately prior to the current Department of Health target of 4 hours. We aimed to investigate whether this suggested that performance data were being manipulated. We collected data from 117 EDs, and 616,067 patient episodes were included in the analysis. Evidence of manipulation of performance data appears to be present in a small proportion of episodes, but because of the numbers involved, it could equate to over 50,000 episodes per year in EDs in England.

Bias↗
PubMed2001

Intra-operative recordings of electrically evoked auditory nerve action potentials in young children by use of neural response telemetry with the nucleus C124M cochlear implant.

The electrically evoked action potential (EAP) was recorded intra-operatively by use of neural response telemetry (NRT) on the Nucleus C124M cochlear implant. The aim of the present study was to investigate the EAP in young children immediately following implant surgery and whilst the children were still anaesthetized. The effect of data collection parameters on the reliability of the EAP was assessed and the relationships of the EAP findings to the intra-operative electrical auditory brainstem response (EABR) and early behavioural threshold levels (T-levels) were also investigated. The study data comprised intra-operative recordings in 60 children. Age at implantation was less than five years in 42 (70%) of the children. Aetiology of deafness was congenital in the majority of children (55, 92%), meningitic in four children and of unknown origin in one child. Optimum test parameters for the intra-operative EAP were an amplifier gain of 40 dB and a delay of 50 micros in order to minimize the effects of amplifier saturation due to stimulus artefact and to maximize the identification of the N1 component. An intra-operative protocol was established which involved recording four stimulus levels on each of the 22 electrodes of the electrode array, the range of stimulus levels being tailored towards the expected EAP thresholds and T-levels so as to identify response threshold. There was significant correlation between the intraoperative EAP thresholds and the early T-levels (Pearson's r = 0.93 ;p<0.01) when a correction factor was introduced based on a reliable behavioural measure of the threshold of electrical stimulation on electrode 10. The intra-operative EAP threshold, when combined with a limited amount of behavioural data, may therefore be used to predict the T-level with a useful degree of accuracy. This result is also supported by the significant correlation observed between the intra-operative thresholds of the EAP and EABR.

Auditory Threshold↗
PubMed2001

Profiles of AEVs for intra- and post-operative integrity test measurements in young children with the Nucleus mini 22 cochlear implant.

Cochlear implantation of young children (<5 years of age) places additional demands on the implant team when compared to older children and adults. For these young children, it is essential to have integrity testing (IT) available to objectively assess the function of the internal device. Unfortunately, very few publications are available which document normal working ranges for IT. Thus the aim of the present study was to establish intra- and post-operative normal ranges for the averaged electrode voltage (AEV) which can be used in the clinical environment to assist in child management. As part of the routine protocol in Nottingham, IT was performed intra-operatively and 2 or 5 years post-operatively in common ground (CG) and pseudo-monopolar 1 (MP1) modes of stimulation on 30 children. All the children were implanted with the Nucleus mini 22 device. Normal ranges were calculated (mean +/- 1 standard deviation (SD)) for both intra- and post-operative measurements. In addition, the post-operative percentage changes in AEV amplitude were calculated for the 2-year and 5-year data groups. Data were excluded from calculations if an electrode was known or suspected to be faulty by visual examination of the AEV profile by an experienced observer. The results demonstrated that the profile of the AEV across the electrode array was preserved between intra- and post-operative recordings, although the amplitude of all AEVs decreased post-operatively. The percentage decrease (mean +/- SD) in (i) CG after 2 years was 69 (+/-16%), (ii) in CG after 5 years was 77 (+/-15%) and (iii) in MPI after 2 years was 35 (+/-1%). IT is a valuable objective tool to assess device function, in particular for young children. Normal AEV ranges are presented which can be used in the clinical environment to aid interpretation of IT performed intra- and post-operatively for CG and MP1 modes. Test data validate the implementation of normal ranges. Electrodes whose values of AEV amplitude fall outside the range should be investigated further.

Child, Preschool↗
PubMed2000

The prognostic value of promontory electric auditory brain stem response in pediatric cochlear implantation.

OBJECTIVE: To test the hypothesis that children with clear promontory electrically evoked auditory brain stem responses (prom-EABRs) would outperform, after cochlear implantation, children who had no prom-EABR preoperatively. DESIGN: A prospective study was undertaken on 47 implanted children assigning them to two groups (group A: 35 children with a clear wave e-V in the preoperative prom-EABR and group B: 12 children with no prom-EABR). Speech perception and speech intelligibility were assessed annually up to 3 yr after implantation with the IOWA sentence test (level A and level B), Connected Discourse Tracking, Categories of Auditory Performance, and Speech Intelligibility Rating. t-test and Mann-Whitney U test were used to compare the above outcome measures in the two groups. RESULTS: There was no statistically significant difference between the two groups on any of the outcome measures at any interval. Moreover, the small differences observed showed no consistent trend toward either group of children. Further analysis revealed that the outcomes have not been affected by possible confounding factors (age at implantation, duration of deafness, preoperative unaided pure-tone thresholds, and number of inserted electrodes). CONCLUSIONS: The results suggest that children with no prom-EABR performed at levels comparable with children who had clear promontory responses preoperatively. The prognostic value of prom-EABR is limited and absence of a prom-EABR is not, by itself, a contraindication for cochlear implantation. However, in selected cases (congenital malformations, cochlear nerve dysplasia or suspected aplasia, narrow internal auditory canal, etc.) the presence of a prom-EABR is a positive finding in the assessment of candidates for cochlear implantation as it confirms the existence of intact auditory neurones.

Audiometry, Pure-Tone↗
PubMed2000

Assessment of the functioning of peripheral auditory pathways after cochlear re-implantation in young children using intra-operative objective measures.

The intra-operative electrical auditory brainstem response (EABR), electrical stapedius reflex threshold (ESRT) and the early post-operative behavioural threshold level (T-level) were recorded in five children undergoing cochlear re-implantation. The aim of the study was to assess objectively the effect of re-implantation on intra-operative objective measures and to investigate neuronal function. The children were aged between 2.06 years and 4.5 years at first implantation. Following failure of the first device, re-implantation was carried out 1.42-5.52 years later. Characteristics of the EABR and ESRT across the electrode array were typical of the expected pattern of responses on both occasions. In particular, the slopes of the amplitude input/output (I/O) functions for wave eV of the intraoperative EABR were similar for both the first and second implants even though absolute thresholds were generally elevated after re-implantation. This elevation in intra-operative threshold was more pronounced than the change in early post-operative behavioural threshold level for electrical stimulation (T-level). Our findings confirm a high level of neuronal survival after re-implantation. Threshold of the intra-operative EABR at the time of re-implantation greatly underestimates the sensitivity of the subsequent early post-operative T-levels.

Auditory Pathways↗
PubMed2000

Assessment of aided ABR thresholds before cochlear implantation.

The Nottingham Paediatric Cochlear Implant Programme (NPCIP) specializes in the cochlear implantation of children under the age of 5 years. The initial stage in the pre-implant evaluation process is audiological assessment. In complex paediatric cases, behavioural audiological assessment may be difficult. In such cases, an objective measure to verify the aided hearing threshold is desirable. This study compares unaided and aided hearing thresholds, by both objective and behavioural techniques, in 20 children (aged <1-10 years). Objective data were collected from auditory brainstem responses (ABR) and behavioural thresholds were measured by use of developmental age-appropriate tests. When comparing the unaided ABR click threshold to the behavioural threshold (obtained from the average of 1-4 kHz warble tones) the ABR threshold was, on average, 9 dB lower (more sensitive). Using the same comparison for aided responses a difference of <5 dB was observed. Unaided ABR thresholds resulted in 35% of subjects responding to the click stimulation (when using a maximum stimulation level of 105 dB nHL), whereas introducing aided ABR measurement elicited positive results in 75% of subjects. The effect of the hearing aid on the stimulus was measured by use of a 2 cc coupler which was connected to a precision sound level meter, whose AC output was recorded onto digital audiotape. Analysis of the resultant output spectra in the frequency domain highlighted signal non-linearity and distortion when using high-intensity stimuli with moderate to high aid gains. In conclusion, aided ABR thresholds are valuable in the management of young children. However, when performing either ABR or behavioural aided hearing threshold measurements it is essential to be aware of the limitations of the hearing aid and the stimulus.

Acoustic Impedance Tests↗
PubMed2000

Audit of 5-year post-implantation routine integrity tests performed on paediatric cochlear implantees.

The Nottingham Paediatric Cochlear Implant Programme (NPCIP) specializes in the implantation of children under 5 years of age. Subsequent tuning of the device and identification of changes in device function for these young children, who may have additional disabilities, can often be challenging. Thus, an objective measure to assess the integrity of the device is desirable. This study compares the device function by both objective and behavioural techniques in 30 children (age at implantation 3-11 years) at five years post-implantation. All children were implanted with the Nucleus Mini 22 device. Objective data were collected from integrity testing (IT) which allowed examination of the functioning of the implant by measuring the electrical stimulus artefact. This does not require the child to give a behavioural response. A protocol for a five-year post-implantation IT is suggested which examines common ground, monopolar and bipolar modes of operation. Behavioural data in the form of threshold (T) and comfort (C) levels were obtained by use of developmental age-appropriate techniques at 5 years post-implantation. Results demonstrate that 43.3% of patients had no electrode faults, 23.3% had potential faults on both behavioural and integrity testing, 6.7% were difficult to assess in terms of defining electrode faults due to partial electrode insertions, 13.3% had potential faults on behavioural testing only and 13.3% of patients had potential faults on IT only. In conclusion, IT is valuable in the identification of faulty electrodes, especially in young children and those with additional disabilities. Implementation of the five-year routine IT affected the management of 30% of patients. This study demonstrates that objective and behavioural techniques are complementary procedures in the ongoing management of paediatric patients.

Child↗
PubMed1999

Integrity of the auditory pathway in young children with congenital and postmeningitic deafness.

This study compares the functional integrity of the auditory pathways of congenitally deaf and postmeningitically deaf children. We used the electrical auditory brain stem response evoked by promontory stimulation to assess 49 profoundly deaf children before cochlear implantation. The age at implantation ranged from 21 months to 15 years (mean 4.5 years). The onset of deafness was either congenital or up to the age of 2 years (mean 5 months). The cause of deafness was meningitis in 19 children (39%) and congenital in 30 (61%). The number of children with identifiable waveform components (eV, eIII, and eII) was significantly greater in the congenitally deaf group. We also analyzed the amplitudes, the latencies, and 4 parameters of the amplitude input-output functions. All the statistically significant differences were in favor of better responses in the congenitally deaf children. These results suggest that the functional status of the peripheral neurons of the auditory pathways may be more intact in congenitally deaf children than in postmeningitic children.

Adolescent↗
PubMed1999

Cochlear nerve aplasia: its importance in cochlear implantation.

OBJECTIVE: The objective of this study was to outline the possible implications and potentially valuable techniques for managing cases in which the neural integrity of the peripheral auditory system is in question. STUDY DESIGN: This study was a retrospective case review. SUBJECT AND METHOD: A 3-year-old child with a profound blilateral sensorineural hearing loss was assessed for suitability of cochlear implantation. Audiologic tests confirmed that the child met the audiologic criteria for cochlear implantation. Computed tomographic scanning and magnetic resonance imaging were undertaken. RESULTS: Computed tomographic scanning showed bilateral narrow internal auditory canals. Magnetic resonance imaging showed the absence of the acousticofacial bundle on the left side and possible atrophy of the bundle on the right. After detailed discussion, the parents elected to proceed with implantation on the right ear using the Nucleus mini-22 cochlear implant. Tuning of the device resulted in myogenic facial activity with no electrically stimulated auditory sensation. Postoperative electrophysiologic testing confirmed the presence of a compound muscle action potential only. CONCLUSIONS: Seven months after implantation, the child was explanted uneventfully. The electrical auditory nerve action potential and the electrically evoked auditory brainstem response, using intracochlear stimulation, are potentially valuable measurements to assess neural integrity before the decision to proceed with implantation is made.

Atrophy↗
PubMed1997

Pharyngeal coin removal in children.

Two cases of coin extraction from the upper third of the oesophagus are described, using a Foley catheter in the accident and emergency department without complication. Although previously reported, the method is not widely used; indeed many junior doctors appear unaware of it. Coins can be removed from this proximal position provided the operator is confident and swift. This appears to be a safe and useful technique, avoiding the need for hospital admission and anaesthesia. It is worth trying before resorting to endoscopy.

Catheterization↗
PubMed1997

Perioperative electrical auditory brain stem response in candidates for pediatric cochlear implantation.

OBJECTIVE: The aim was to investigate the feasibility of recording the electrical auditory brain stem response (EABR) evoked by electrical stimulation at the promontory (Prom-EABR) as a tool to assist selection of the ear for cochlear implantation in young children. STUDY DESIGN: The study group consisted of young children for whom the decision to proceed with implantation with the Nucleus mini 22-channel cochlear implant (Cochlear (UK) Ltd., London, UK) had already been made. SETTING: The Prom-EABR was recorded after the children had been anesthetised, but before the start of surgery. PATIENTS: A group of 25 children (11 boys and 14 girls), whose age at implantation ranged from 2 years 11 months to 6 years 8 months (mean age, 4 years 5 months), were investigated. INTERVENTION: Recordings of the Prom-EABR were used to determine which ear would receive the cochlear implant, providing there were no preexisting contraindications regarding selection of the ear. MAIN OUTCOME MEASURE: It has been suggested from earlier studies that the characteristics of the amplitude input/output (I/O) function of the EABR are related to neuronal survival. If the ear with the "better" I/O function is chosen for implantation, it might be expected that these children will perform better on average than those in whom the ear has been selected at random. RESULTS: Reliable recordings of the Prom-EABR were achieved in 40 ears (80%) of the 50 ears in the study. In 20 of the 25 children the technique was actively employed for selection of the ear for implantation. CONCLUSIONS: Recording of the Prom-EABR in the operating theater is a viable technique. Future analysis of long-term outcome measures of performance with the implant will confirm or dispute the benefit of ear selection using the Prom-EABR.

Child↗
PubMed1997

Electric auditory brain stem response in pediatric patients with cochlear implants.

OBJECTIVE: To introduce four comprehensive electrical auditory brain stem response (EABR) parameters that objectively measure the input-output function and may be the base of comparison in related studies. MATERIALS AND METHODS: In 53 children (106 ears), recordings of the EABR evoked by electrical stimulation at the promontory were made at the time of surgery after the child was anesthetized and before cochlear implantation. RESULTS: Of the 106 ears studied, 81 (76.4%) produced clearly defined responses. These responses were used to develop a package of four comprehensive EABR parameters (slope, maximal slope, relative growth rate, and maximal relative growth rate) that measure objectively the input-output function. The methods of calculation are described in detail. CONCLUSION: These parameters may help us to refine and make more consistent the subjective EABR evaluation. They will also enable a comparison of the results from different cochlear implant centers and promote the progress of related research.

Adolescent↗
PubMed1997

Multichannel cochlear implantation in postmeningitic and congenitally deaf children.

OBJECTIVE: To test the view that prelinguistic postmeningitic deaf (PMD) children outperform congenitally deaf children (CD) in the first year following cochlear implantation. STUDY DESIGN AND PATIENTS: We evaluated 85 children with ages (at implantation) ranging from 1.9 years to 13.5 years (mean age 5.4 years). The Listening Progress scale was used to assess the developing use of audition 3, 6, and 12 months after implantation. RESULTS: In contrast to previous reports, the PMD children achieved statistically significantly lower scores than CD children.

Child↗
PubMed1996

Intraoperative electrophysiological and objective tests after cochlear re-implantation in a young child.

The electrically evoked auditory brainstem response (EABR) and stapedius reflex threshold (ESRT) are routinely recorded during implant surgery with the Nucleus 22 channel cochlear implant in the Nottingham Paediatric Cochlear Implant Programme and are extremely valuable in the management of young implanted children. These intraoperative tests were carried out in a young child on the occasion of the first implantation and then after re-implantation 17 months later following malfunction of the first device. The surgical experiences of the first implantation and the re-implantation were both straightforward. Recordings of the intraoperative EABR and ESRT were typical of the expected pattern of responses on both occasions and there was only a small reduction in threshold sensitivity after re-implantation. These investigations provide valuable objective information to support and assist with the management of re-implantation in a young child.

Child, Preschool↗
PubMed1996

Efficiency of tests used to screen for cerebello-pontine angle tumours: a prospective study.

With increasing use of imaging in the investigation of cerebello-pontine angle (CPA) tumours, the role of audio-vestibular and electrophysiological testing has changed. Field performance data on the efficiencies of these tests to screen for CPA tumours are lacking, but must be known to choose an appropriate testing strategy. A prospective observational study of 237 patients attending a neuro-otology clinic for audio-vestibular investigation was carried out. The aim was to provide field performance data on which to base an effective protocol to screen for CPA tumours. All patients presenting at the ENT department and meeting any of the following criteria were referred to the neuro-otology clinic and included in the study: (1) asymmetrical sensorineural hearing loss, (2) unexplained asymmetrical tinnitus with normal bearing thresholds, (3) unilateral bearing difficulties with normal hearing thresholds and (4) other neurological indications. In addition to audio-vestibular and auditory brainstem response (ABR) investigation, every patient underwent computed tomography (CT), with magnetic resonance imaging (MRI) in cases having marginal results on CT, to exclude or confirm the presence of a tumour. Pass or fail on each test was based on a priori criteria from other studies. Eighteen patients were found to have CPA tumours. ABR testing was the only effective procedure for screening, but had some limitations. A contingent protocol using ABR in all cases except those with asymmetrical tinnitus and normal bearing thresholds, those with severe hearing loss, and those with neurological signs, was retrospectively defined: the exceptions would go straight to CT. This protocol would have missed two of the 18 tumour patients. CT scanning alone would have missed one small intra-canalicular tumour, which was picked up on MRI triggered by abnormal ABR. Based on the results from the present study we conclude there is no effective screening protocol for detecting CPA tumours, as MRI scanning with gadolinium enhancement will identify virtually all tumours. Where MRI is available but waiting lists are long, the described strategy using ABR to select priority referrals for MRI scanning is recommended.

Adult↗
PubMed1995

Raised ABR threshold after suction aspiration of glue from the middle ear: three case studies.

Between 1991 and 1993, 13 children (25 hearing ears) underwent recordings of the auditory brain stem response (ABR) under a general anaesthetic. The anaesthetic technique was similar for each child. Fourteen of these ears had fluid aspirated after myringotomy with insertion of grommets prior to the auditory brain stem response investigation. On subsequent hearing assessment six of these 14 ears (43 per cent) showed clear evidence of a threshold shift of 15 dB or greater. Eleven ears had either dry myringotomies or did not have a myringotomy prior to ABR and none of these showed evidence of a temporary threshold shift. Using Fisher's Exact probability test this difference is significant (p = 0.034). We feel it is important to report these observations so that unexpected high ABR thresholds following aspiration of glue are interpreted with caution.

Adolescent↗