Athanasios Bibas

The effects of mass loading the ossicles with a floating mass transducer on middle ear transfer function.

Hypothesis: The aim of this study was to measure the mass loading effect of an active middle-ear implant (the Vibrant Soundbridge) in cadaver temporal bones. Background: Implantable middle ear hearing devices such as Vibrant Soundbridge have been used as an alternative to conventional hearing aids for the rehabilitation of sensorineural hearing loss. Other than the obvious disadvantage of requiring implantation middle ear surgery, it also applies a direct weight on the ossicular chain which, in turn, may have an impact on residual hearing. Previous studies have shown that applying a mass directly on the ossicular chain has a damping effect on its response to sound. However, little has been done to investigate the magnitude and the frequency characteristics of the mass loading effect in devices such as the Vibrant Soundbridge. Methods: Five fresh cadaver temporal bones were used. The stapes displacement was measured using laser Doppler vibrometry before and after the placement of a Vibrant Soundbridge floating mass transducer. The effects of mass and attachment site were compared with the unloaded response. Measurements were obtained at frequencies between 0.1 and 10 kHz and at acoustic input levels of 100 dB sound pressure level. Each temporal bone acted as its own control. Results: Placement of the floating mass transducer caused a reduction of the stapes displacement. There were variations between the bones. The change of the stapes displacement varied from 0 dB to 28 dB. The effect was more prominent at frequencies above 1,000 Hz. Placing the floating mass transducer close to the incudostapedial joint reduced the mass loading effect. Conclusion: The floating mass transducer produces a measurable reduction of the stapes displacement in the temporal bone model. The effect is more prominent at high frequencies.

Surgical anatomy of the external branch of the superior laryngeal nerve and its clinical significance in head and neck surgery

Injury of the external branch of the superior laryngeal nerve (EBSLN) increases the morbidity following a variety of neck procedures and can have catastrophic consequences in people who use their voice professionally. Identification and preservation of the EBSLN are thus important in thyroidectomy, parathyroidectomy, carotid endarterectomy, and anterior cervical spine procedures, where the nerve is at risk. There are large variations in the anatomical course of the EBSLN, which makes the intraoperative identification of the nerve challenging. The topographic relationship of the EBSLN to the superior thyroid artery and the upper pole of the thyroid gland are considered by many authors to be the key point for identifying the nerve during surgery of the neck. The classifications by Cernea et al. ([ 1992a ] Head Neck 14:380–383; [ 1992b ] Am. J. Surg. 164:634–639) and by Kierner et al. ([ 1998 ] Arch. Otolaryngol. Head Neck Surg. 124:301–303), as well as clinically important connections are discussed in detail. Along with sound anatomical knowledge, neuromonitoring is helpful in identifying the EBSLN during neck procedures. The clinical signs of EBSLN injury include hoarseness, decreased voice projection, decreased pitch range, and fatigue after extensive voice use. Videostroboscopy, electromyography, voice analysis, and electroglottography can provide crucial information on the function of the EBSLN following neck surgery. Clin. Anat. 21:99–105, 2008.

Intratympanic and systemic steroids for sudden hearing loss.

Objective To investigate the therapeutic efficacy of intratympanic dexamethasone combined with systemic prednisolone in patients with idiopathic sudden sensorineural hearing loss (ISSNHL). Study Design Prospective, quasirandomized, multicenter clinical trial. Setting One university hospital and 2 affiliated hospitals. Patients A total of 92 eligible patients with ISSNHL were allocated into 2 groups. Patients in the control group were treated with systemic prednisolone alone. Patients of the combined treatment group received additionally 3 intratympanic dexamethasone injections within 5 days. Main Outcome Measures The main outcome measures used were the differences between pretreatment and posttreatment pure-tone audiometry averages (PTAs) and speech discrimination scores (SDSs). Successful treatment was defined as a greater than 10 dB improvement in PTA and 15% in SDS. The final assessment of hearing was performed 3 months after completion of treatment. Results Significant hearing recovery was observed in 31 (67.39%) of 46 cases, and in 24 (52.17%) of 46 control patients. Patients receiving combination therapy had a median improvement in PTA of 23.12 dB and a median increase in SDS of 32%. In the control group, the median hearing gain was 16.87 dB and 18%, respectively. The differences between the 2 groups were not statistically significant (p = 0.10 and p = 0.13). However, after performing a post hoc analysis by excluding individuals with profound hearing loss (PTA, >90 dB), the combined treatment group showed significant improvement compared with the control group (p = 0.04). No serious complications or adverse reactions were reported. Conclusion The addition of intratympanic steroids to the conventional systemic steroid therapy may provide a safe and potentially effective therapeutic option in patients with mild-to-severe ISSNHL.

Equivalent Noise Level Generated by Drilling Onto the Ossicular Chain as Measured by Laser Doppler Vibrometry: A Temporal Bone Study†

Background: Inadvertent drilling on the ossicular chain is one of the causes of sensorineural hearing loss (HL) that may follow tympanomastoid surgery. A high‐frequency HL is most frequently observed. It is speculated that the HL is a result of vibration of the ossicular chain resembling acoustic noise trauma. It is generally considered that using a large cutting burr is more likely to cause damage than a small diamond burr.

Effect of cochlear implant electrode insertion on middle-ear function as measured by intra-operative laser Doppler vibrometry.

HYPOTHESIS The aim of this study was to investigate the impact of cochlear implant electrode insertion on middle-ear low frequency function in humans. BACKGROUND Preservation of residual low frequency hearing with addition of electrical speech processing can improve the speech perception abilities and hearing in noise of cochlear implant users. Preservation of low frequency hearing requires an intact middle-ear conductive mechanism in addition to intact inner-ear mechanisms. Little is known about the effect of a cochlear implant electrode on middle-ear function. METHODS Stapes displacement was measured in seven patients undergoing cochlear implantation. Measurements were carried out intra-operatively before and after electrode insertion. Each patient acted as his or her own control. Sound was delivered into the external auditory canal via a speaker and calibrated via a probe microphone. The speaker and probe microphone were integrated into an individually custom-made ear mould. Ossicular displacement in response to a multisine stimulus at 80 dB SPL was measured at the incudostapedial joint via the posterior tympanotomy, using an operating microscope mounted laser Doppler vibrometry system. RESULTS Insertion of a cochlear implant electrode into the scala tympani had a variable effect on stapes displacement. In three patients, there was little change in stapes displacement following electrode insertion. In two patients, there was a significant increase, while in a further two there was a significant reduction in stapes displacement. This variability may reflect alteration of cochlear impedance, possibly due to differing loss of perilymph associated with the electrode insertion. CONCLUSION Insertion of a cochlear implant electrode produces a change in stapes displacement at low frequencies, which may have an effect on residual low frequency hearing thresholds.

Hearing loss in Paget's disease: a temporal bone histopathology study.

Background Hearing loss in Paget’s disease of bone (PDB) is typically mixed and bilateral. Although different mechanisms have been proposed, the pathophysiology of hearing impairment remains unclear. Objective The purpose of this study is to describe the histopathologic findings of temporal bones in patients with PDB and elucidate possible pathologic mechanisms related to hearing impairment. Methods This is an archival human temporal bone study of 8 subjects diagnosed with Paget’s disease from the temporal bone collection of the UCL Ear Institute. Results A fractured stapes footplate was observed in 1 temporal bone and stapes footplate fixation in 2 other specimens. Obliteration of Cotugno’s canal by extensive bone remodeling was observed in 78% of temporal bones. An intracochlear vestibular schwannoma was observed in 1 specimen (previously reported in the literature). Other findings include microfissures and microfractures of the otic capsule, bleeding in the scalae, strial atrophy, and cystic lesions in the spiral ligament. Conclusion This study is the first to report a fractured stapes footplate, as a causative lesion of conductive hearing loss in PDB. Extensive bone remodeling around Cotugno canal also was a frequent finding, not reported before in the literature. We hypothesize that sensorineural hearing loss in patients with PDB of the temporal bone may, in some cases, be attributed to obliteration of Cotugno’s canal by remodeling pagetoid bone, thus obstructing the venous drainage of the cochlea, with a subsequent effect on the function of stria vascularis and spiral ligament. This seems to be consistent with experimental studies in animals.

A Clinically Oriented Introduction and Review on Finite Element Models of the Human Cochlea

Due to the inaccessibility of the inner ear, direct in vivo information on cochlear mechanics is difficult to obtain. Mathematical modelling is a promising way to provide insight into the physiology and pathology of the cochlea. Finite element method (FEM) is one of the most popular discrete mathematical modelling techniques, mainly used in engineering that has been increasingly used to model the cochlea and its elements. The aim of this overview is to provide a brief introduction to the use of FEM in modelling and predicting the behavior of the cochlea in normal and pathological conditions. It will focus on methodological issues, modelling assumptions, simulation of clinical scenarios, and pathologies.

External video PC card for digital recording during otolaryngological endoscopic examination.

Video recording during otolaryngological examination, such as nasal and laryngeal and otoendoscopy, allows medical record documentation and facilitates the follow-up procedure. It can also provide health care practitioners with valuable material that can serve for teaching purposes, comparative studies, and patient education. Digital recorders that are now available can provide otolaryngologists with reliable high-resolution video files, but the relevant equipment still remains bulky and expensive. The aim of this paper is to present a reliable and low-cost digital recording system based on a personal computer and an external video card that can be used in all endoscopic procedures.

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.

Diagnosis of balance disorders using decision support systems based on data mining techniques

In this work we present the decision support of the EMBalance platform. EMBalance is a platform for the management of balance disorders in terms of diagnosis, treatment and evolution. The EMBalance platform aims to extend existing but generic and currently uncoupled balance modelling activities leading to a multi-scale and patient-specific balance model, which will be incorporated in a Decision Support System (DSS), towards the early diagnosis, prediction and the efficient treatment planning of balance disorders. The diagnosis part of the decision support system uses various data ranging from demographic characteristics to clinical examinations, auditory and vestibular tests. Currently we present some initial technical choices and indicative results of the decision support system for diagnosing balance disorders, based on data mining techniques and clinical guidelines.