Maurizio Barbara

Aquaporin-2 expression in the mammalian cochlea and investigation of its role in Meniere's disease.

The expression pattern of aquaporin-2 (AQP2), a vasopressin regulated member of the aquaporin gene family, in the cochlea and its potential role in Menieres disease was investigated. RT-PCR screen of multiple rat tissues identified AQP2 transcripts in the cochlea, testis and kidney and an absence of tissue-specific splice variants. The level of AQP2 transcript in the cochlea was 10-fold lower relative to its expression in the testis and kidney. Western blot analysis demonstrated a single, 29 kDa band in the membrane fractions from cochlea, testis and the kidney. In the rat and mouse cochlea, AQP2 was expressed in the structures bordering the endolymph, including Reissners membrane, the organ of Corti, inner and outer sulcus cells and the spiral limbus. A mutation screen of AQP2 in 12 individuals with Menieres disease did not identify any sequence alterations or mutations within the four coding exons of AQP2 and their intron-exon junctions. The physiological role of AQP2 in water transport and its expression pattern in the cochlea suggests an important role for AQP2 in fluid homeostasis of the inner ear; however, its role in the pathogenesis in Menieres disease remains to be established.

Vestibular impairment and cochlear implantation

Conclusion. Cochlear implantation (CI) may induce vestibular impairment soon after surgery as well as after implant activation. This impairment seems to be independent from the cause of deafness and can be considered a possible complication from the intra-operative trauma and, to minor degree, from the ongoing electric stimulation. It would also seem that vestibular damage occurs independently from the likelihood of post-operative hearing deterioration. In unilateral selected CI cases, vestibular examination can be proposed as additional pre-operative exam for selection of the ear to be implanted. Objectives. This study has been planned in order to get evidence of eventual impairment of the vestibular apparatus after cochlear implantation as well as to verify whether the impairment could be related to different variables, such as cause of deafness, concomitant hearing deterioration, surgical trauma and duration of electrical stimulation. Method. Charts from two different populations of implantees have been reviewed, 21 from a prospective, 72 from a retrospective study, respectively. All the patients were implanted with Clarion® devices of different generation. Vestibular testing was based on rotatory, caloric (when possible) and stabilometric measurements, which were carried out pre-operatively and at the following different times: 5 weeks after CI surgery, and 30, 60 and 90 days after CI activation. Hearing thresholds were also assessed in those patients who showed signs of vestibular impairment as well as in a group of patients without vestibular disorders (control). Patients belonging to the retrospective group were all asked to fill a questionnaire regarding their balance condition. Results. In 14.3% of the prospective study group, a grade I and II spontaneous nystagmus was evidenced pre-operatively and remained unchanged during the whole assessment period. A grade II spontaneous nystagmus was present in 3 patients (21.4%) of the same group after surgery. In the immediate post-operative period, vestibular impairment was displayed as true rotational vertigo in 21.4% and unsteadiness in 42.8% of the study group. Severe unsteadiness was present during the first 2 days after activation in 14.3% of the subjects. In 21.4% of the patients a VPPB episode occured. In the retrospective study group, 26.4% of the subjects referred pre-operative dizziness and 25 patients (34.7%) referred immediate post-operative vertigo episodes, which remained in a milder form after CI activation in 12% of them. The hearing threshold showed to deteriorate in both vestibular-impaired and control CI population without significant difference.

Rapid Maxillary Expansion for the Treatment of Nasal Obstruction in Children Younger Than 12 Years

OBJECTIVE To assess short- and long-term effects of rapid maxillary expansion (RME) on nasal flow in young children. Since RME has been reported to positively influence nasal obstruction in subjects with respiratory problems by reducing nasal resistance, a similar efficacy of RME could be expected in children with deciduous and/or mixed dentition who are affected by maxillary constriction and nasal obstruction from a different cause. DESIGN Prospective study of children younger than 12 years, with different grades of malocclusion and oral breathing. Data included active anterior rhinomanometry in both the supine and orthostatic positions, as well as radiographic cephalometric measurements. SETTING Tertiary care university hospital. Data were prospectively collected from 2005 to 2007. PATIENTS Nasal flow and resistance were measured in 65 children younger than 12 years, with mixed or deciduous dentition and different grades of malocclusion and oral breathing. MAIN OUTCOME MEASURE Efficacy of RME for resolution of maxillary constriction. RESULTS After RME, an improvement of nasal flow and resistance has been recorded in patients, in the supine position, who presented both anterior and posterior obstruction. Less notable changes were shown in isolated forms of obstruction and in the orthostatic position. CONCLUSION In cases of maxillary constriction and nasal airway obstruction, RME has proved to be efficient for the improvement of nasal respiration in children via a widening effect on the nasopharyngeal cavity.

Transcutaneous bone-conduction hearing device: audiological and surgical aspects in a first series of patients with mixed hearing loss

Abstract Conclusions: The Bonebridge® (BB) transcutaneous bone conductive implant (BCI) may overcome some of the issues related to a percutaneous BCI, such as management of the external screw, delayed activation or possible skin complications. Moreover, it has been shown to enable a functional outcome similar to percutaneous BCI in both conductive and mixed types of hearing loss. Objectives: To obtain clinical data from a preliminary series of patients implanted with a new transcutaneous BCI. Methods: Four subjects affected by conductive/mixed hearing loss underwent implantation of the BB by two approaches: the transmastoid, presigmoid approach and the retrosigmoid approach. Soundfield thresholds were assessed with warble tones in a soundproof audiometric booth, and word recognition scores (WRSs) as speech reception thresholds (SRTs) were used to compare the unaided versus the post-implantation condition. Results: The surgical procedure was completed in all cases, with only minor intraoperative divergence from the CT-based planning and no postoperative complications. The average improvement of the SRT in quiet with the BB in comparison to the unaided condition was 36.25 dB. All the implanted subjects reached SRT values below 65 dB, indicating a better understanding in quiet, with 100% word recognition.

Totally implantable middle ear device for rehabilitation of sensorineural hearing loss: preliminary experience with the Esteem®, Envoy

Conclusion. According to the first series of implanted patients, Esteem 2® technology can be regarded as a safe and reliable system for hearing restoration in case of moderate to severe sensorineural hearing loss. Objectives. To assess the benefit deriving from implantation of a totally implantable middle ear device in subjects affected by moderate to severe sensorineural hearing loss, the Esteem 2® (Envoy Medical), as measured through pure tone audiometry testing carried out during the different postoperative fitting sessions. Patients and methods. Six patients have been operated on since July 2007. Selection was carried out via preoperative audiometric tests and thorough counseling, which considered information on previous experience with conventional hearing aids as well as each patients motivation to undergo a surgical application. Specific surgical training is needed to accommodate routine surgical steps along with less familiar steps, such as placement of cement material and overall fixation of the system. Results. The surgical procedure took a long time, but a reduced duration was recorded in the last procedure compared with the first one. The implantation process induced a deterioration in hearing thresholds, which fully recovered after activation of the device. A postoperative hearing gain could be measured in all three patients: in this regard, the perceived quality of sound was shown to be better than could be expected by the measurable hearing gain.

The totally implantable middle ear device ‘Esteem’ for rehabilitation of severe sensorineural hearing loss

Abstract Conclusion: The Esteem device proved to offer beneficial results in subjects suffering from high frequency, severe bilateral sensorineural hearing loss (SNHL) and may be considered as an alternative procedure to conventional hearing aids (HAs) or electroacoustic stimulation (EAS) systems. Objectives: Since the Esteem totally implantable device has been shown to offer positive results among patients with moderate SNHL, this middle ear implant has also been suggested for subjects with a worse degree of hearing loss in order to predict its extended application, also in the nearly cochlear implantation range. Methods: Esteem implantation was carried out in 21 subjects with a mild (n = 3), moderate (MHL, n = 9) or severe (SHL, n = 9) degree of SNHL. The two latter groups, i.e. MHL and SHL, were compared in terms of preoperative versus postoperative pure tone and speech reception thresholds (SRTs). Similarly, they were also compared for the outcome from quality of life (QoL) questionnaires, such as the general Glasgow Benefit Inventory (GBI) and COSI. Results: In the whole sample, mean hearing threshold levels improved from 70 to 48 dB; in the MHL group the mean hearing threshold level improved from 64 to 42 dB; in the SHL group the mean hearing threshold level improved from 82 to 58 dB. GBI and COSI scores were only slightly better in the MHL group than in the SHL group.

Local pressure protocol, including meniett, in the treatment of Ménière's disease: Short-term results during the active stage

Treatment of Ménières disease (MD) is still controversial and pressure changes transmitted to the inner ear have been reported to have effects similar to those of other non-surgical therapies. This paper reports on a clinical trial of MD patients which has been carried out using a portable piece of equipment, called Meniett ® , which delivers a pulsed, controlled, positive pressure to the middle ear, provided that a ventilation tube (VT) has previously been inserted. A comparison was made of the number of vertigo spells during the 2 months before treatment and during the 40-day treatment period. In addition, within this latter period a comparison was made between use of VT and use of VT+Meniett. Use of VT only had a positive effect in 90% of patients, with either absence ( n = 10; 50%) or marked reduction ( n = 8; 40%) in episodes of vertigo. When Meniett was also applied, stabilization of the positive effect on vertigo was registered, with a concomitant improvement in hearing threshold in 2 patients (10%). Although a longer and more reliable long-term follow-up of this treatment is needed, it is possible to propose the use of this therapeutic approach as it has been proven to induce a dramatic improvement in the symptoms affecting patients with Ménières disease during reactivation of the disease.Treatment of Ménières disease (MD) is still controversial and pressure changes transmitted to the inner ear have been reported to have effects similar to those of other non-surgical therapies. This paper reports on a clinical trial of MD patients which has been carried out using a portable piece of equipment, called Meniett, which delivers a pulsed, controlled, positive pressure to the middle ear, provided that a ventilation tube (VT) has previously been inserted. A comparison was made of the number of vertigo spells during the 2 months before treatment and during the 40-day treatment period. In addition, within this latter period a comparison was made between use of VT and use of VT + Meniett. Use of VT only had a positive effect in 90% of patients, with either absence (n = 10: 50%) or marked reduction (n = 8; 40%) in episodes of vertigo. When Meniett was also applied, stabilization of the positive effect on vertigo was registered, with a concomitant improvement in hearing threshold in 2 patients (10%). Although a longer and more reliable long-term follow-up of this treatment is needed, it is possible to propose the use of this therapeutic approach as it has been proven to induce a dramatic improvement in the symptoms affecting patients with Ménières disease during reactivation of the disease.

External ear canal exostosis and aquatic sports.

Many reports suppose that the development of aural exostosis depends on the action of an irritative stimulus like frequent and repeated cold water contact. This survey studies the incidence of this lesion in a group of 433 athletes practicing aquatic sports on a highly competitive level. Among these, water activities like sailing and deep-sea diving, which up to now were never considered, were also studied. 32 exostoses were found to affect 12 subjects monolaterally and 20 subjects bilaterally. Not one of a control group of 476 athletes was found to be affected by aural exostosis. For each athlete in this study the following parameters are considered: age and sex, type of sport, total amount of hours spent in water contact, aural pathology history and otoscopic findings. The authors suggest the existence of facilitating factors other than total water contact time, as shown by the absence of a precise correlation between this parameter and the presence of the aural hyperostotic lesion.

Effect of superoxide dismutase and allopurinol on impulse noise-exposed guinea pigs--electrophysiological and biochemical study

OBJECTIVE To investigate the protective effect of two anti-reactive oxygen species (ROS) substances, copper-zinc superoxide dismutase (CuZn-SOD) and allopurinol, in impulse noise-exposed guinea pigs. MATERIAL AND METHODS Allopurinol or CuZn-SOD were administered intraperitoneally before exposure to 125 dB SPL noise centered at 2.0-3.0 kHz, with a repetition rate of 4/s, for 1.8 h. Hearing thresholds were tested by means of electrocochleography after implanting the animals with permanent electrodes. The presence of lipoperoxides in the guinea pig cochleae exposed to noise-induced oxidative stress was determined by means of the dosage of malondialdhyde, evaluated by measuring the content of thiobarbituric acid reactive substances in perilymph samples. RESULTS Acoustic stress induced ROS formation and both allopurinol and CuZn-SOD exerted a protective effect on the cochlea. Comparison of compound action potential thresholds in different animal groups showed that the temporary threshold shift was significantly lower in treated animals than in those without pharmacological protection. CONCLUSION The protective effect of the antioxidant agents demonstrates that, even at a high level of impulse noise exposure, a metabolic mechanism of cochlear damage may still play an important role in noise-exposed sensorineural hearing loss.

Laser Doppler Measurement of Cochlear Blood Flow Changes During Conditioning Noise Exposure

Using laser Doppler flowmetry, cochlear blood flow was assessed in Mongolian gerbils exposed to noise. Anesthetized animals were surgically implanted with permanent electrodes and then exposed for 10 consecutive days (6 h on/18 h off) to an octave band noise centered at 4 kHz (85 dB SPL). The auditory brainstem responses and the blood flow in the basal turn of the cochlea were compared with those of gerbils not exposed to noise. The exposed animals developed an initial threshold shift, followed by a progressive reduction in threshold shift up to complete recovery at the end of the test. In the exposed animals, a reduction in the cochlear blood flow during the first 4 days of exposure was observed, which was then followed by a progressive increase up to the end of the test. The results of this study exclude a possible role of the microvasculature of the lateral cochlear wall in determining the resistance to 4 kHz frequency noise exposure.