Randomised clinical trial: transoral incisionless fundoplication vs. sham intervention to control chronic GERD.

BACKGROUND: Until recently only two therapeutic options have been available to control symptoms and the esophagitis in chronic gastro-oesophageal reflux disease (GERD), i.e. lifelong proton pump inhibitor (PPI) therapy or anti-reflux surgery. Lately, transoral incisionless fundoplication (TIF) has been developed and found to offer a therapeutic alternative for these patients. AIM: To perform a double-blind sham-controlled study in GERD patients who were chronic PPI users. METHODS: We studied patients with objectively confirmed GERD and persistent moderate to severe GERD symptoms without PPI therapy. Of 121 patients screened, we finally randomised 44 patients with 22 patients in each group. Those allocated to TIF had the TIF2 procedure completed during general anaesthesia by the EsophyX device with SerosaFuse fasteners. The sham procedure consisted of upper GI endoscopy under general anaesthesia. Neither the patient nor the assessor was aware of the patients' group affiliation. The primary effectiveness endpoint was the proportion of patients in clinical remission after 6-month follow-up. Secondary outcomes were: PPI consumption, oesophageal acid exposure, reduction in Quality of Life in Reflux and Dyspepsia and Gastrointestinal Symptom Rating Scale scores and healing of reflux esophagitis. RESULTS: The time (average days) in remission offered by the TIF2 procedure (197) was significantly longer compared to those submitted to the sham intervention (107), P < 0.001. After 6 months 13/22 (59%) of the chronic GERD patients remained in clinical remission after the active intervention. Likewise, the secondary outcome measures were all in favour of the TIF2 procedure. No safety issues were raised. CONCLUSION: Transoral incisionless fundoplication (TIF2) is effective in chronic PPI-dependent GERD patients when followed up for 6 months. Clinicaltrials.gov: CT01110811.

Bone-anchored hearing aids: current status in adults and children.

The BAHA is the only cochlea stimulator in clinical use using bone conduction as the mode of stimulation. Sound transmitted through bone conduction is a natural way of hearing and the fundamentals of bone conduction are presented. The simple but important procedure has been refined and is presented in some detail. As the BAHA is approved by the Food and Drug Administration for children, aspects relevant for this age group will be addressed. The future includes semi-implantable BAHA, percutaneous electrical coupling, and a BAHA for tinnitus suppression.

A bone-anchored hearing aid for patients with pure sensorineural hearing impairment: a pilot study.

This pilot study assesses the potential benefits of an optimized bone-anchored hearing aid (BAHA) for patients with a mild to moderate pure sensorineural high frequency hearing impairment. The evaluation was conducted with eight first-time hearing aid users by means of psycho-acoustic sound field measurements and a questionnaire on subjective experience; all of the patients benefited from the BAHA. On average, the eight patients showed improvement in PTA threshold of 3.4 dB and in speech intelligibility in noise of 14%. Seven of the subjects, also fitted with present standard air conduction hearing aids (ACHA) found the ACHA thresholds to be improved more than the BAHA ones. In speech tests, the ACHA was only slightly better; these patients chose between their different hearing aids according to the sound environment. Although the BAHA was preferred for wearing and sound comfort, it cannot be used as the sole aid for patients with pure sensorineural impairment.

Vibration characteristics of bone conducted sound in vitro.

A dry skull added with damping material was used to investigate the vibratory pattern of bone conducted sound. Three orthogonal vibration responses of the cochleae were measured, by means of miniature accelerometers, in the frequency range 0.1-10 kHz. The exciter was attached to the temporal, parietal, and frontal bones, one at the time. In the transmission response to the ipsilateral cochlea, a profound low frequency antiresonance (attenuation) was found, verified psycho-acoustically, and shown to yield a distinct lateralization effect. It was also shown that, for the ipsilateral side, the direction of excitation coincides with that of maximum response. At the contralateral cochlea, no such dominating response direction was found for frequencies above the first skull resonance. An overall higher response level was achieved, for the total energy transmission in general and specifically for the direction of excitation, at the ipsilateral cochlea when the transducer was attached to the excitation point closest to the cochlea. The transranial attenuation was found to be frequency dependent, with values from -5 to 10 dB for the energy transmission and -30 to 40 dB for measurements in a single direction, with a tendency toward higher attenuation at the higher frequencies.

Sensitivity to bone-conducted sound: excitation of the mastoid vs the teeth.

The sensitivity of nine subjects to bone-conducted sound was measured at three positions: osseointegrated percutaneous titanium implants in the temporal bone, the skin-covered mastoid and the teeth. Voltage levels supplied to a bone-anchored hearing aid (BAHA) transducer and to an Oticon bone-transducer were measured and the thresholds obtained at the three positions were compared. Using the mechanical impedance of the teeth, the parameters of a first order model for the vibration transmission through the teeth was calculated. Also, the equivalent force thresholds were calculated from the voltage threshold levels. The sensitivity to bone-conducted sound, for both voltage and force thresholds, conformed fairly well at the three positions for frequencies below 1 kHz; however, above 1 kHz, bone-conducted sound applied at the titanium implant becomes more sensitive than at the two other positions investigated. It was concluded that the teeth can be used for the application of bone-conducted sound, in particular for pre-operative assessment of a BAHA and to facilitate service and quality control of such a hearing device.

Diffraction-like effects in a highly concentrated W/O emulsion: a PFG NMR study.

Diffraction-like effects have been observed by applying pulsed field gradient (PFG) nuclear magnetic resonance (NMR) to a highly concentrated water-in-oil (W/O) emulsion, made up of the nonionic surfactant C12E4 [CH3(CH2)11(OCH2CH2)4OH], n-decane, and brine [1 wt% NaCl(aq) solution]. The pulsed field gradient NMR data show one pronounced maximum and the shoulder of a second maximum in the attenuation curve of the NMR signal from water, the so-called Bragg interference peaks. From the diffraction-like peaks, the average distance (center to center) between the emulsion droplets can be obtained, in this case related to the average size of an emulsion droplet. Furthermore, we note that the long-term stability of the emulsion can be followed by pulsed field gradient NMR.

A miniaturized artificial mastoid using a skull simulator.

A miniaturized artificial mastoid of size and weight that allow calibration and measurement of bone conduction hearing aids in a conventional audiometric soundproof box has been developed. Its level of mechanical impedance corresponds to the standard IEC 373 (1990) within the frequency range 250 Hz to 8 kHz. The miniaturized artificial mastoid consists of three parts: coupler, skull simulator (TU-1000), and an external electrical correction filter. The coupler is a highly damped mass-spring system designed to give the miniaturized artificial mastoid mechanical impedance in accordance with the standard IEC 373 (1990). It was found that the miniaturized artificial mastoid yielded results that are in correspondence with results obtained with the Brüel & Kjaer type 4930 artificial mastoid for frequencies above 450 Hz. Thus, at these frequencies, the miniaturized artificial mastoid can be used for audiometer calibration as well as measurement of bone conduction hearing aids.

The bone-anchored hearing aid: reference quantities and functional gain.

One of the most important parameters of a hearing aid is its gain characteristics. Under ideal circumstances, the gain and the functional gain (FG) are the same for an air conduction device. This is not the case, however, with bone conduction devices, e.g., the bone-anchored hearing aid (BAHA). In this article, the relation between the gain and the FG is derived for bone conduction devices including the BAHA. Reference quantities used when measuring bone conduction devices also are presented.

Linearity of sound transmission through the human skull in vivo.

The linearity of sound propagation through the human skull was investigated. One male subject, equipped with bilateral skin-penetrating titanium fixtures for attachment of bone-anchored hearing aids, was studied thoroughly. Three different methods were used: comparison of the frequency response functions estimated at different signal levels (using stepped sine as well as random noise), comparison of the coherence function at different signal levels (using random noise), and the Hilbert transform of the estimated frequency response function. Frequencies from 0.1 to 10 kHz and signal levels up to 77 dB HL at discrete frequencies were used. No indication of any significant nonlinear behavior was found with the three methods used.

Force threshold for hearing by direct bone conduction.

The bone-anchored hearing aid is connected, by means of a skin-penetrating bayonet coupling, to an implanted titanium fixture. Hence, direct bone conduction (dbc) excitation is used. Since no international standard of audiometric zero for dbc force threshold exists, it is of general interest to determine the dbc force threshold for normal hearing subjects. Two different methods have previously been applied to estimate the relation between bone conduction (bc) and dbc thresholds. One preliminary problem was to make a measurement of the output-force level of dbc transducers, which is equivalent to the situation in situ. A skull simulator, TU-1000, has been designed for measuring the output-force level of dbc transducers. The skull simulator does, in an adequate way, reflect the mechanical point impedance of the human skull. This opportunity to determine equivalent dbc force thresholds has motivated the present study in which a linear relation between the dbc force threshold and the bc force threshold was estimated. The estimate found in the present study conforms fairly well with the two previously found estimates. It is suggested that the estimate found in the present study be used as the reference equivalent threshold force level for dbc.

The bone-anchored hearing aid. Design principles, indications, and long-term clinical results.

This article presents a summary of design principles, indications, and clinical results obtained with the bone-anchored hearing aid (BAHA). Hearing through bone conduction and mechanical stimulation of the skull with percutaneous versus transcutaneous excitation and the functional capability of the ear level BAHA sound processor is presented. Moreover, the surgical procedure is described and the success rate to establish and maintain osseointegration is presented together with the frequency of skin reactions at the implant site. The audiologic and questionnaire results achieved with the BAHA is also presented and discussed.

The bone-anchored hearing aid: principal design and audiometric results.

The principle of the bone-anchored hearing aid (BAHA) is simple: sound vibrations are directly transmitted to the skull bone via a skin-penetrating titanium implant, and then are further transmitted to the cochlea, bypassing the middle ear. The present paper summarized the audiometric results from 122 patients with an average follow-up time of 5.6 years. When herein-suggested indications for treatment with the bone-anchored sound processor HC 300 are followed, the success rate is very high. The improved quality of life reported by the patients is a combination of improved quality of sound (warble tone threshold, speech reception threshold, and discrimination in noise), improved comfort, and relief from middle ear and ear canal disease occasioned by conventional hearing aids.

Resonance frequencies of the human skull in vivo.

Patients with skin penetrating titanium implants in the temporal bone, for attachment of bone-anchored hearing aids, have made it possible to investigate the free-damped natural frequencies (resonance frequencies) of the human skull in vivo. The resonance frequencies of the skull of six subjects were investigated. Teh resonance frequencies were extracted from two frequency response functions (acceleration/force) measured on each subject: One point measurement where the force and acceleration were both measured at the same point, and one transcranial measurement where the acceleration was measured contralaterally. Between 14 and 19 resonance frequencies were identified for each subject in the frequency range 500 Hz to 7.5 kHz. The two lowest resonance frequencies were found to be on the average 972 (range 828-1164) and 1230 (range 981-1417) Hz. The relative damping coefficients of all resonances were found to be between 2.6 and 8.9%. Due to the relatively high damping coefficients, it is assumed that the resonance frequencies do not significantly affect bone conducted sound. In the transcranial measurements, however, a few large antiresonances were found which may affect bone-conducted sound. Intersubject variations were large, probably due to individual variations in skull geometry and in mechanical parameters. The results were shown to be consistent with previous results obtained on dry skulls. No obvious correlation between lowest resonance frequency and skull size was found.

Ten years of experience with the Swedish bone-anchored hearing system.

In 1977, a new phase began in hearing rehabilitation of patients with chronic middle and external diseases and atresias. Thus far, these patients have had to rely on conventional bone conduction and air conduction devices that for various reasons give poor rehabilitation. The principle of the new treatment, made possible by the Swedish bone-anchored hearing system, is simple: sound vibrations are directly transmitted to the skull bone via a skin-penetrating titanium implant and then are further transmitted to the cochlea, bypassing the middle ear. The present paper summarizes our results in 147 patients over 10 years, including a total of 6,334 follow-up months. No significant rate of skin infections was observed. In over 93% of the observations, no sign of adverse skin reaction was seen. When herein-suggested indications for treatment with the bone-anchored sound processor HC-200 are followed, the success rate is over 90%. The improved quality of life reported by the patients is a combination of improved quality of sound, improved comfort, and relief from middle ear and ear canal disease occasioned by conventional hearing aids.

Percutaneous vs. transcutaneous transducers for hearing by direct bone conduction.

There is a substantial need for improvement of the hearing situation for patients, with chronic middle ear or ear canal disorders. To improve hearing for these patients, two different bone conduction hearing systems have been developed. The Nobelpharma Auditory System HC 200-the bone-anchored hearing aid we present here-uses a percutaneous transducer; whereas the Audiant device, developed by Dr. Jack Hough, uses a transcutaneous transducer. In percutaneous transmission, the transducer is directly coupled to the bone by means of a permanent skin penetration, whereas in transcutaneous transmission one part of the transducer is implanted and the other part is kept outside the intact skin and soft tissue. Comprehensive audiologic assessments indicate great differences in performance between the two systems. These differences probably originate in differences in length of gap and in different suspension properties of the two transducer systems. This article will demonstrate that large gaps, such as in the transcutaneous transducer, can be devastating for power consumption, maximum output capability, and second harmonic distortion. Since the properties of the suspension in the transcutaneous transducer are not under adequate control and the complication risk of permanent skin penetration is low, we continue to concentrate our efforts on percutaneous transducer systems.