Italian Fast Speech Reception Threshold Test: A New Method to Investigate Adult Auditory Impairment in Noise.

INTRODUCTION: Purpose of our study was to compare two competing methods of performing bisyllabic word speech audiometry for the detection of the 50% speech reception threshold in noise (SRT50). METHODS: Classic method is performed submitting multiple word lists at a fixed signal-to-noise ratio. A newer Fast method - Italian Fast Speech Reception Threshold 50 (IFastSRT50) - is performed by means of program software with a single list of bisyllabic words and noise intensity shifting. RESULTS: Means comparison between SRT50 Classic and IFastSRT50 shows a slight significant correlation (r = 0.263; p = 0.044) and a wide significant difference: SRT50 Classic = -2.763 dB (SD = 4.1) and IFastSRT50 = -7.803 dB (SD = 2.1) (p < 0.0001). There is a high difference between the test execution time means (SRT50 Classic = 11 min, IFastSRT50 = 2 min; p < 0.0001). The correlation between test results and execution times was higher for SRT50 Classic than IFastSRT50. CONCLUSION: IFastSRT50 test is a reliable method to quickly investigate signal-to-noise ratio needed to obtain 50% of recognition scores with bisyllabic words; it allows less execution time than SRT50 Classic method and can avoid patient fatigue and other limitations of different speech discrimination tests in noise as sentences based ones.

Bone-Anchored Hearing Devices for Single-Sided Deafness: A New Preoperative Evaluation Protocol and Widening of Indications Proposal.

INTRODUCTION: Bone-anchored hearing devices (BAHD) are well-known good solution for single-sided deafness (SSD). Despite power extension of recently introduced BAHD with implanted active transducer, with indications up to 65 dB Hl of bone conduction (BC) threshold on the implanted side, their indications for SSD still remain better than 25 dB on the good ear, with regards to bone conduction thresholds. The aim of this study was to assess the possibility to enlarge BAHD indications for SSD by means of a newly proposed candidacy evaluation protocol, which includes a new software-aided method. METHODS: 20 SSD patients (mean age 56 years, 9 females, and 11 males) were divided into two groups: group A (10 patients, BC <25 dB Hl on the hearing side) and group B (10 patients, BC between 25 and 35 dB Hl). Recipients were submitted to bisyllabic words speech audiometry in silence and to authors' newly proposed IFastSRT50 test by means of software which shift noise intensity of a single word list on the basis of correct recipient recognition responses. A sound speaker for signal (bisyllabic words) and noise (babble) was disposed at 1 m from the deaf side of the patient. An earphone covering only the good ear of the recipient was used in order to perform its air conduction masking with white noise. A BAHD test device was disposed on the mastoid of the deaf side. Both signal and masking intensities were set to 55 dB SPL in order to mask airway conduction on the good ear without masking its bone way interaural conduction from the BAHD tester. RESULTS: With BAHD tester turned off, no recognition was detected. Speech audiometry with BAHD tester turned on revealed mean values of 92% for group A and 89% for group B, with a difference of 3.0% (χ2 = 0.285 and p = 0.5935). As for IFastSRT50 with BAHD tester turned on, mean signal-to-noise ratio value to obtain 50% of recognition was -6.89 for group A and -6, with a difference of 0.89 (t = 1,201 and p = 0.2453). CONCLUSION: BAHD are confirmed to be a good solution for SSD cases. The absence of statistically significant differences in our two tested groups suggests that newer implanted active transducer device indications should be extended up to 35 dB Hl on the hearing ear. The IFastSRT50 is a reliable and quick method to enhance preoperative candidacy evaluation.

Preoperative vestibular evoked myogenic potentials (VEMPs), caloric test, and pure tone audiometry to identify the vestibular nerve branch of schwannoma origin: preliminary results in a series of 26 cases.

Vestibular schwannoma (VS) is a benign tumor which develops in the internal auditory canal and the cerebellopontine angle, potentially diminishing hearing or balance. Most VS tumors arise from one of two vestibular branches: the superior or inferior vestibular nerve. Determining the specific nerve of origin could improve patient management in terms of preoperative counseling, treatment selection, and surgical decision-making and planning. The aim of this study was to introduce a preoperative testing protocol with high accuracy to determine the nerve branch of origin. The nerve of origin was predicted on the basis of preoperative vestibular evoked myogenic potentials (VEMPs), caloric stimulation test, and pure tone audiometry on 26 recipients. The acquired data were entered into a statistic scoring system developed to allocate the tumor origin. Finally, the nerve of origin was definitively determined intraoperatively. Receiver operating characteristic (ROC) curves analysis of preoperative testing data showed the possibility of predicting the branch of origin. In particular, ROC curve of combined VEMPs absence, nystagmus detectable at caloric stimulation, and PTA < 75 dB HL allowed to obtain high accuracy for inferior vestibular nerve implant of the tumor (area under the curve-AUC = 0.8788, p = 0.012). In 24 of 26 cases, the preoperatively predicted tumor origin was the same as the origin determined during surgery. Preoperative audiological and vestibular evaluation can predict the vestibular tumor branch of origin with high accuracy. Despite the necessity of larger prospective cohort studies, these findings may change preoperative approach, possible functional aspects, and counseling with the patients.

Combined Endoscopic/Microscopic Cochlear Implantation Through the Oval Window.

Standard round window (RW) cochlear implantation is a well-described technique. Implantation might be difficult in patients with inner and middle ear anomalies, in some cases because of not achieving adequate exposure to the RW, with a related higher risk of complications such as facial nerve injury. It is proposed a combined microscopic/endoscopic oval window approach in a 63 year old man affected by bilateral Menière disease, with bilateral severe sensorineural hearing loss, speech discrimination score for bysillabic words under 40% and a hidden RW by anomalous facial nerve course. All electrodes entered the cochlear with good freefield thresholds and auditory ability results. A partial marginalis nerve palsy occurred at the second postoperative day and completely reversed at 2 months from surgery. Endoscopicassisted oval window cochlear implantation may be a safe alternative surgical technique in cases where surgeons are not able to access RW.

A Multicenter Clinical Evaluation of Data Logging in Cochlear Implant Recipients Using Automated Scene Classification Technologies.

Currently, there are no studies assessing everyday use of cochlear implant (CI) processors by recipients by means of objective tools. The Nucleus 6 sound processor features a data logging system capable of real-time recording of CI use in different acoustic environments and under various categories of loudness levels. In this study, we report data logged for the different scenes and different loudness levels of 1,366 CI patients, as recorded by SCAN. Monitoring device use in cochlear implant recipients of all ages provides important information about the listening conditions encountered in recipients' daily lives that may support counseling and assist in the further management of their device settings. The findings for this large cohort of active CI users confirm differences between age groups concerning device use and exposure to various noise environments, especially between the youngest and oldest age groups, while similar levels of loudness were observed.

Maps created using a new objective procedure (C-NRT) correlate with behavioral, loudness-balanced maps: a study in adult cochlear implant users.

In uncooperative patients, electrical compound action potential (ECAP) thresholds are reliable in predicting T-levels, but are not in determining the C-level profile. The present study aims to assess if the C-level profile can be predicted by a new objective procedure (C-NRT) which uses the amplitude growth function (AGF) and is based on the assumption that equal ECAP amplitudes elicit equal loudness percepts. This is a correlational study conducted in five tertiary care referral hospitals with 21 post-lingually deaf adult cochlear implant users. Two maps were created: a behavioral, bitonal balanced (BB) map and an objective map, in which T-levels were the same as in the BB map, and C-levels were obtained with C-NRT. C-NRT consisted of performing the AGF of nine electrodes, and of setting the current level eliciting a 100 µV ECAP amplitude as C-level in the map. AutoNRT was also measured. Main outcome measures were correlation between behavioral C-profile level, objective C-profile level, behavioral T-profile level and objective T-profile (AutoNRT) level; disyllabic word recognition scores in quiet and in noise conditions (SNR = + 10 and 0) with both maps. A strong correlation was found between behavioral and C-NRT-derived C-levels (mean per electrode correlation: R = 0.862, p < 0.001). C-NRT could predict behavioral C-levels with a greater accuracy than AutoNRT. Word recognition was significantly better with BB maps only in the quiet condition (p = 0.002). C-NRT is more accurate than AutoNRT in predicting the C-level profile in adult cochlear implant users. This finding encourages future application in uncooperative patients, especially in very young children.

Combined posterior tympanotomy/endomeatal access in cochlear implantation.

Alternative techniques for cochlear implant surgery have been described, such as endomeatal- and suprameatal-alone approaches, without traditional posterior tympanotomy. A combined posterior tympanotomy/endomeatal approach is proposed as a way to enhance surgical safety and effectiveness. 64 patients, 34 men and 30 women, mean age 28 (range 1-81 years), 26 pre-verbal and 38 post-verbal, were submitted to cochlear implantation, 32 by means of the described combined posterior tympanotomy/endomeatal approach and 32 with traditional posterior tympanotomy-alone approach. Good anatomic and functional results were observed, with intraoperative improvements in visibility and accessibility of cochleostomy site in difficult cases without any complication, such as tympanic membrane perforation, external canal skin lesions, or extrusion at 12 months. No significant differences were found with traditional technique complication rates excepting for partial insertion data, with statistically significant better results with combined access. The combined posterior tympanotomy/endomeatal approach facilitates the array insertion in conditions of bad exposition/accessibility of promontory and round window. Moreover, this double-way access hinders an incomplete or incorrect positioning. It should be always considered as an alternative to the traditional posterior tympanotomy of one-way access.

Transtympanic electrical stimulation for immediate and long-term tinnitus suppression.

Tinnitus is a common symptom which often becomes disabling, affecting the emotional and psychosocial dimensions of life. There are many reports describing tinnitus suppression or attenuation through electrical stimulation of the ear, provided either by cochlear implants or by transtympanic stimulation. Our study project aims to assess the effects of electrical promontory stimulation (EPS) on persistent disabling tinnitus. We enrolled 11 patients affected by postlingual monoaural or binaural profound hearing loss and disabling tinnitus in the worse ear. EPS was performed with direct continuous positive current delivered by an active platinum-iridium needle electrode connected to a promontory stimulator device. The short-term effect on tinnitus was assessed during and immediately after the stimulation. Long-term effects were estimated after one month by comparing pre- and post-EPS Tinnitus Handicap Inventory (THI) scores. Immediately after EPS, five patients (45.4%) reported complete suppression and four (36.4%) reported attenuation of tinnitus. Two patients (18.2%) said it was unchanged. After one month, the THI score was reduced in five patients (45.4%) and remained unchanged in the other six patients (54.6%). The beneficial effects of EPS on tinnitus might be explained by interference with tinnitus generating circuits such as the dorsal cochlear nucleus and the inferior colliculus and by modification of cortical activity. EPS is to be considered a worthwhile attempt at tinnitus suppression, and could help select candidates for the positioning of an implantable electrical stimulator that might provide longer-term beneficial effect on tinnitus.

Electric to acoustic pitch matching: a possible way to improve individual cochlear implant fitting.

Poor pitch resolution has been shown to have negative implications for speech and music perception in implanted patients. Surprisingly, works on the subject have not focused much on the impact that the non-correspondence between frequencies allocated to electrodes and perceived frequencies could have on speech and music perception. The aim of the present study is to investigate the correlation between pitch mismatch and speech performance with the implant, and to ascertain the effects of mismatch correction through a mapping function making a personalized frequency reallocation possible. We studied ten postlingually deaf adult patients with detectable bilateral residual hearing, implanted in our Clinic with Cochlear Nucleus devices. In each test session, we asked the patients to find the best match between the pitch elicited by the residual ipsilateral and contralateral pure tones and the pitch elicited by stimulation of electrodes. We also assessed patients' vowel and consonant recognition performance. Finally, in the only implanted patient in our clinic who had bilateral residual hearing and used a Digisonic DX10/C device, which makes manual electrode-by-electrode frequency reallocation possible, we modified electrode-assigned frequency ranges on the basis of the pitch matching test results. We found that in none of the studied patients, the electric-to-acoustic pitch matching corresponds to the theoretical assignment pattern. A very strong correlation was detected between the electric-to-acoustic pitch mismatch and patient's speech performance. In the Digisonic patient, a remarkable improvement in all phoneme recognition scores was obtained 1 month after frequency reallocation. In the light of our results, we propose to assess, whenever possible, any frequency-to-electrode mismatch in all implanted patients, and correct it through mapping programs allowing manual frequency reallocation for the pitch-matched electrodes, and automated allocation of the non-tested electrodes. Cochlear implantation should therefore be proposed when residuals for all frequencies are still present, at least in one ear, so as to allow optimal alignment between allocated and subjectively perceived frequencies.

Tinnitus modifications after cochlear implantation.

Tinnitus can be defined as a phantom sensation in the absence of an external sound. In our study, we evaluated the effect of cochlear implant on tinnitus evolution. Among adult, postlingually deaf patients who underwent cochlear implantation at our clinic, we selected 20 subjects with pre-implantation tinnitus (group A) and 10 subjects without pre-implantation tinnitus (group B). Pre- and post-surgery tinnitus was assessed through two questionnaires: the first one dealing with tinnitus characteristics and psychosocial impact, and the second one represented by THI, an internationally validated score of evaluation of the effects of tinnitus on patient's emotions and activities of daily living. None of the patients belonging to group B developed tinnitus after surgery. As for group A, 40% of patients declared suppression of tinnitus, 30% attenuation of tinnitus after surgery, 25% reported tinnitus was unchanged and 5% reported worsening of tinnitus. In the nine patients with bilateral tinnitus (45%), after implantation tinnitus disappeared from both sides in four patients and attenuated bilaterally in four patients. A comparison between pre- and post-implantation THI scores showed decreased score in 65% of cases, unchanged score in 30% and increased score in 5%. The beneficial effect of cochlear implant on tinnitus, reported by a majority of patients, could be due to acoustic masking, to direct electrical stimulation of the acoustic nerve, and above all to a possible cochlear implantation dependent reorganization of the central auditory pathways and associative cerebral areas. In the light of these results, the authors propose (1) to include tinnitus in the selection criteria of which ear to implant; (2) to consider implantation eligibility for patients with bilateral severe hearing loss associated with severe tinnitus; and (3) to inform patients about the small risk of post-operative tinnitus worsening.

Differences between electrode-assigned frequencies and cochlear implant recipient pitch perception.

CONCLUSION: This study demonstrated an evident mismatch between frequencies assigned to electrodes and frequencies evoked by stimulation of those same electrodes in implanted patients. We propose that the mapping procedures should include, whenever possible, a comparison with homolateral residual hearing in order to obtain an appropriate frequency range assignation for each electrode. OBJECTIVES: The study aimed to investigate the correspondence between the frequencies assigned to each electrode and those actually perceived by the cochlear implant patient. PATIENTS AND METHODS: We studied five post-lingually deaf adults with detectable residual hearing in the implanted and in the contralateral ear, who had each received a Cochlear implant. An ACE standard setting was used for mapping. The patients were asked to match the electric pitch with the acoustic one following presentation of pure tones to both the implanted and the contralateral ear. RESULTS: In almost all patients the two most apical electrodes evoked higher frequencies than those assigned by the mapping software (E22 = 188-313, E21 = 313-438 Hz). Therefore, electric stimulation seems not to determine pitch sensations for frequencies <500 Hz. For most electrodes there is no correspondence between the acoustic pitch and the assigned frequency ranges. Moreover, these results were almost always different when stimulating the implanted and the contralateral ear.

Residual hearing in cochlear implant patients.

Preservation of residual hearing should be a desirable outcome of implant surgery. Prevention of neural degeneration due to loss of residual hair cells, together with the continuous progress in cochlear implant technology should be able to preserve cochlear integrity as well as possible. The degree of hearing preservation may vary depending on surgical approach, maximum insertion depth and other factors not uniformly considered to date. The aim of this retrospective case controlled study is to evaluate residual hearing after cochlear implant surgery. In particular, we analyzed data obtained with use of two different kinds of electrode arrays, with and without rigid introductor (stylet). We report the results on 37 patients with measurable preoperative hearing thresholds, mean age of 28 years (5-70 years), having the following implants: seven Advanced Bionics, four Med-El, 24 Cochlear, two MXM; 19 of them were performed using the stylet and the other 18 without it. A minimally invasive surgical approach was performed with a short retroauricular incision and a 1.2 mm cochleostomy. A complete electrode array insertion was obtained in all patients. Responses to pure-tone stimuli were measured for each ear in pre-implantation conditions and 3-12 months after surgery. After implantation 14 patients (38%) showed no hearing threshold variation, 29 (78%) maintained an appreciable hearing threshold level in the implanted ear, 8 (22%) had a total loss of residual hearing. Median increases of threshold levels were, in all 37 studied patients, 5, 10, 10 and 5 dB HL, respectively, for 125, 250, 500 and 1 kHz. For the 18 patients having implants without the stylet median increases of threshold levels were 0, 10, 5 and 7 dB HL; in the stylet group, they were 10, 5, 5 and 10 dB HL. On a comparison between the stylet and the non-stylet group, no significant differences in mean hearing threshold worsening were found. Data seem to suggest that cochlear function is less sensitive to mechanical trauma during implant surgery than was thought. Besides, electrode array stiffness seems not to influence preservation of cochlear residual functional integrity. Finally, the authors hypothesize a direct spiral ganglion activation under strong mechanical stimulation.

Residual hearing thresholds in cochlear implantation and reimplantation.

Implant and reimplantation surgery should be carried out with preservation of residual hearing. The aim of this study is to evaluate the effects of such a surgery on hearing threshold. We report the results on 40 patients, 20 males and 20 females, aged between 5 and 70 (mean 29) years, 16 pre-verbal and 24 post-verbal, with measurable pre-operative auditory thresholds. We used the following implants: Advanced Bionics, Med-El, Cochlear, and MXM Digisonic. Four of the patients underwent cochlear reimplantation owing to device failure. A complete insertion was obtained in all patients. Responses to pure-tone stimuli were evaluated in each ear in pre-implant conditions and 3 months after cochlear implant or reimplantation. The explantation was performed with minimal cochlear trauma and preservation of the explanted electrode integrity. 35% showed no change of the hearing threshold, 45% showed a slight worsening of the hearing threshold level in the implanted ear, and 20% had a total loss of residual hearing. Median increases of threshold levels were 10, 5, 10 and 3 dB HL respectively for 125, 250, 500 and 1 kHz. In the group of 4 patients who underwent cochlear reimplantation, 2 showed no variation of the hearing threshold, 1 preserved an appreciable hearing threshold, and 1 had a total loss of residual hearing. The data seem to suggest that hearing function is rather resistant to mechanical trauma during implant and reimplant surgery; the authors hypothesize a role for direct spiral ganglion activation under intense mechanical stimulation.

Expression of vascular endothelial growth factor and its receptors in the cochlea of various experimental animals.

CONCLUSION: The results of this study indicate that vascular endothelial growth factor (VEGF) may be an important regulator of the vascular network of the inner ear and suggest that the VEGF signalling pathway may play a role in pathophysiologic conditions. OBJECTIVE: In order to clarify the role of vascular growth factor in the modulation of the vascular network of the cochlea, we studied the expression of VEGF and its receptors-fms-like tyrosine kinase (Flt-1) and foetal liver kinase (Flk-1)-in the inner ear of 3-month-old rodents of different species: C57BL/6J mice, Wistar albino rats and Hartley albino guinea pigs. MATERIAL AND METHODS: Qualitative immunohistochemical studies were performed by using specific antibodies to VEGF and its receptors on paraffin sections of the cochlea. The expression levels of VEGF and its receptors were quantified by means of Western blot analysis of cochlea protein extracts. RESULTS: We demonstrated that VEGF and its receptors are expressed in the cochlea and described their distribution in the inner ear. In particular, VEGF and Flt-1 are present at the level of the modiolus, spiral ganglion, spiral ligament, basilar membrane, supporting cells, outer and inner hair cells and stria vascularis. Flk-1 was less strongly expressed in the cochlea and was not detected in the organ of Corti.