A swallowed foreign body that uncovered an undiagnosed bowel pathology.

This report details a unique presentation of Crohn's disease in a patient who inadvertently swallowed the cap of a USB mass storage device and subsequently developed intestinal obstruction and underwent a limited right hemicolectomy. Imaging, photographs and histology are described with discussion of surgical outcomes.

Electrode features for hearing preservation and drug delivery strategies.

BACKGROUND/AIMS: Reducing the risk of hearing loss after cochlear implantation requires optimization of the electrode array to minimize the physical trauma caused by insertion and placement. Furthermore, the electrode design must be optimized for atraumatic surgical approaches. Even greater levels of protection may be achieved by the use of a drug during and after implantation. The electrode array offers a potential vehicle for drug delivery. METHODS: This article reviews the laboratory and clinical data available thus far relating to the importance of electrode design parameters for trauma minimization, and the possibility of further reduction through pharmaceutical intervention. Candidate drugs were identified through literature review and laboratory evaluation. The most promising have been investigated in vitro and in animal models of implantation trauma. Three delivery devices are currently under development to satisfy the specific demands of different therapy regimes. The delivery profiles of each were evaluated through both modelling and bench testing and the concepts investigated in vitro and in vivo. RESULTS: Current evidence favours a thin, flexible electrode array with wires in a zigzag shape. Steroids and an apoptosis inhibitor (AM111) performed well in animal models of electrode trauma and are both good drug candidates for reduction of the risk of hearing loss after implantation. Semi-chronic dexamethasone elution, acute drug delivery by intracochlear catheter, and longer-term delivery through diffusion from a reservoir were all shown to be feasible. CONCLUSION: An extensive programme focussed on minimizing hearing loss through device optimization and the development of new technologies has yielded positive results and new concepts for further development and clinical application.

Reduced binocular beat visual evoked responses and stereoacuity in patients with Duane syndrome.

PURPOSE: To study the effects that the abnormal eye movements of patients with Duane retraction syndrome have on the development of binocular function. METHODS: Pattern reversal visual evoked responses (VEPs) to 15-minutes-of-arc and 60-minutes-of-arc checks and binocular beat VEPs to diffuse sinusoidally modulated 18- and 20-Hz stimuli were recorded in 10 patients with Duane retraction syndrome who maintain binocular function by using an abnormal head posture. Visual acuity, stereoacuity, and eye movements were measured. The results have been compared to those from 10 normal subjects. RESULTS: The patients with Duane retraction syndrome had reduced stereoacuity compared to the normal control group (TNO mean, 82.5 seconds of arc compared to 37.5 seconds of arc; Titmus mean, 143 seconds of arc compared to 44 seconds of arc). The binocular beat VEPs showed a significantly reduced difference beat response at 2 Hz in the patients with Duane syndrome compared to normal subjects (mean signal-to-noise ratio 2.40 +/- 1.05 compared to 4.30 +/- 2.66; t = 2.21, df = 18, P < 0.05). Binocular enhancement of the P100 pattern reversal amplitude to 15-minute checks was increased in these patients, because of a reduction of the monocular P100 amplitudes compared to the normal group. CONCLUSIONS: Patients with Duane syndrome who maintain binocular function using an abnormal head posture have reduced stereoacuity and show electrophysiological evidence of reduced cortical binocular interaction.

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.

Electric response audiometry in young children before cochlear implantation: a short latency component.

OBJECTIVE: Evaluation of a short latency component (SLC) observed in profoundly deaf young children during recordings of the auditory brain stem response (ABR) before cochlear implantation. DESIGN: Seventy young children (ages 2 to 11 yr) were investigated as part of their routine audiologic and diagnostic assessment, before cochlear implantation. The ABR was evoked using click stimuli and tone pips (500 Hz and 1 kHz) at intensity levels up to 105 dB nHL. The incidence of the SLC arising at a latency of 3 msec with high level click stimuli, in addition to residual ABR waves, was assessed. RESULTS: An SLC was observed in a total of 18 of the 70 children investigated. It was present in 15 out of 31 congenitally deaf children (48%) compared with only 2 out of 33 children deafened after meningitis (6%). A chi-squared test employing a 2 x 2 contingency table shows that this dependency on etiology of deafness is highly statistically significant (p < 0.001). The presence of the SLC in the congenitally deaf children is related to age at the time of the Electric Response Audiometry test and is more likely to be observed in the younger child (p < 0.01). CONCLUSIONS: Interpretation of the ABR in profoundly deaf children should take into consideration the possible presence of the SLC. An evoked potential arising from stimulation of the vestibular system, particularly the vestibular nuclei, is proposed as a likely origin for this component. Damage to sensory cells in the vestibular portion of the labyrinth might explain why an SLC is seen rarely in cases of deafness after meningitis.

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.

Measurement of the activating function of magnetic stimulation using combined electrical and magnetic stimuli.

The technique of combined magnetic and electrical stimulation of a peripheral nerve was used to determine the effectiveness of the combined stimulus and its dependence on the relative positioning of electrodes and stimulator coil along the axis of the nerve. The results were used to determine the magnetic stimulation-activating function of a long, straight nerve in the arm, and are shown to be consistent with published theoretical models constructed under conditions of simplified tissue geometry. With appropriate positioning of the two stimulators and similar tissue current waveforms, both enhancement and inhibition of an electrical stimulus were demonstrated and the maximum amplitude of the combined stimulus approached the arithmetic sum of that produced by each stimulator individually.

Magnetic nerve stimulation: the effect of waveform on efficiency, determination of neural membrane time constants and the measurement of stimulator output.

We describe the first investigation into the effect on stimulation efficiency of varying the output of a commercial magnetic stimulator based on our original clinical design. Over the range of magnetic field waveforms considered, it is shown that the stored energy required to achieve stimulation, both cortically and in the periphery, varies by approximately 2:1. Greater efficiency is obtained by using shorter risetime magnetic fields. This results in more effective stimuli for the same stored energy, or, for the same stimulus, a decrease in energy storage, power dissipation and peak currents, thus simplifying hardware design. A novel method of processing the data obtained from different waveforms is presented which enables neural membrane time constant to be calculated. Data from normal subjects is presented showing both peripheral and neural time constants to be of order 150 microseconds. The cortical measurements represent the first non-invasive determination of cortical membrane time constant in man. Time constant measurements using magnetic stimulation may be clinically useful because they give information concerning the electrical properties of the nervous system not available from present techniques. Finally a method of quantifying the output of magnetic stimulators and coils is described which enables laboratory comparisons to be made, and takes into account magnetic field waveforms and coil geometry. The proposed symbol for this new measurement is Et150 with units volt seconds/meter.

Circadian rhythm of heart rate in the rabbit: prolongation of action potential duration by sustained beta adrenoceptor blockade is not due to associated bradycardia.

Six litters of six young rabbits were injected intraperitoneally, two per litter, with saline, alinidine, or nadolol once or twice daily for two weeks. In four litters successful radiotransmissions of electrocardiograms were recorded once hourly for four days before and during treatment. Alinidine and nadolol produced an overall mean bradycardia in comparison with saline treated animals, the effect of alinidine exceeding that of nadolol. At 48-70 hours after the end of treatment the hearts were used for in vitro electrophysiological study. Nadolol, but not alinidine, induced a prolongation of action potential duration compared with that of saline treated littermates in both atrial and ventricular muscle. An incidental observation was that heart rate in the rabbit followed a circadian rhythm, heart rates being slower in the morning and faster in late afternoon and evening. The circadian rhythm was attenuated but not abolished by alinidine and nadolol. These results suggest that if prolongation of action potential duration by sustained beta blockade in patients after myocardial infarction contributes to protection against sudden death (by a class III antiarrhythmic action) then alinidine would not be expected to provide a comparable prophylaxis.