A New Floating Piezoelectric Microphone for Fully Implantable Cochlear Implants in Middle Ear.

OBJECTIVE: Our team designed a long-lasting, well-sealed microphone, which uses laser welding and vacuum packaging technology. This study examined the sensitivity and effectiveness of this new floating piezoelectric microphone (NFPM) designed for totally implantable cochlear implants (TICIs) in animal experiments and intraoperative testing. METHODS: Different NFPM frequency responses from 0.25 to 10 kHz at 90 dB SPL were analyzed using in vivo testing of cats and human patients. The NFPM was tested in different positions that were clamped to the ossicular chains or placed in the tympanic cavity of cats and human patients. Two volunteers' long incus foot and four cats' malleus neck of the ossicular chain were clamped with the NSFM. The output electrical signals from different locations were recorded, analyzed, and compared. The NFPM was removed after the test without causing any damage to the middle-ear structure of the cats. Intraoperative tests of the NFPM were performed during the cochlear implant surgery and the cochlear implant surgery was completed after all tests. RESULTS: Compared with the results in the tympanic cavity, the NFPM could detect the vibration from the ossicular chain more sensitively in cat experiments and intraoperative testing. We also found that the signal output level of the NFPM decreased as the acoustic stimulation strength decreased in the intraoperative testing. CONCLUSION: The NFPM is effective in the intraoperative testing, making it feasible as an implantable middle-ear microphone for TICIs. LEVEL OF EVIDENCE: 4 Laryngoscope, 134:937-944, 2024.

Delayed Facial Nerve Paralysis After Vestibular Schwannoma Resection.

OBJECTIVE: To report the long-term outcome of delayed facial nerve paralysis (DFNP) after surgical resection of vestibular schwannoma and evaluate the influence of various factors on the prognosis of facial nerve function. METHODS: Of 265 patients who underwent surgical excision of VS through a retrosigmoid approach between April 2019 and October 2021, 15 (5.7%) developed DFNP and were retrospectively studied. Preoperative and postoperative data were collected and analyzed. RESULTS: The mean age of patients with DFNP was 42.6 years (range, 27-63 years), and 11 (73.3%) were male. Tumor size ranged from 12 to 37 mm (mean 24 mm) in largest dimension. All patients had normal (House-Brackmann [HB] I) facial nerve function preoperatively. Immediate postoperative facial nerve function was HB I in 12 patients (80%) and HB II in 3 patients (20%). The mean severity of DFNP onset was HB 4.7 (range, HB III-V). The average day of onset was postoperative day 12.6 (range, day 5-28). At 1-year follow-up, 12 patients (80%) were HB I, 1 patient (6.7%) was HB III, and 2 patients (13.3%) were HB IV. All patients who were HB III and IV at the last follow-up had immediate postoperative facial nerve function of HB II. CONCLUSIONS: Most patients who develop DFNP have a favorable prognosis. However, a small proportion of patients with deteriorated facial nerve function immediately after surgery have poor long-term outcomes, despite confirmation of their facial nerve integrity anatomically and by electrical stimulation.

Endaural Endoscopic Atticoantrotomy (Retrograde Mastoidectomy) using a Constant Suction Bone-drilling Technique.

Endoscopic middle ear surgery is a widely employed minimally invasive surgical technique to address middle ear and mastoid pathology. Bone drilling is the main technical challenge of endoscopic middle ear surgery. The accompanying video describes the detailed protocol of a constant-suction bone-drilling technique and the procedure of endaural exclusive endoscopic atticoantrotomy (retrograde mastoidectomy) using this technique. The main components of this bone-drilling technique include a soft and flexible suction tube, which is placed into the tympanic cavity to provide constant suction, and a soft sleeve, which is wrapped around the drill shaft to prevent the high-speed rotating shaft from damaging the lens of the endoscope. With these simple modifications, the traditional otological electrodrill can be used for drilling a tiny endaural incision in endoscopic middle ear surgery. Based on this bone-drilling technique, endaural endoscopic atticoantrotomy (retrograde mastoidectomy) can be successfully established for the removal of various amounts of bone, depending on the extent of the lesion. The short-term postoperative outcome seems promising.

Surgical management of intraoperatively diagnosed facial nerve schwannoma located at internal auditory canal and cerebellopontine angle - our experiences of 14 cases.

BACKGROUND: Facial nerve schwannomas located at internal auditory canal and cerebellopontine angle (IAC/CPA FNS) were diagnosed intraoperatively, it poses a therapeutic dilemma to the surgeon. OBJECTIVE: To report our experience in managing IAC/CPA FNS and to propose a treatment strategy. METHODS: A total of 14 patients with IAC/CPA FNS who were diagnosed intraoperatively and treated by operation between 2015 and 2019 were retrospectively studied. RESULTS: Unilateral hearing loss was the most common symptom and all these patients had normal facial nerve function preoperatively. Surgical approaches used in these patients including translabyrinthine (2 cases), retrosigmoid (RS) (11 cases), and middle cranial fossa (MCF) approach (1 case). Eight patients underwent partial resection, three patients underwent subtotal resection and three patients had complete tumor removal with facial nerve reconstruction. All partial resection patients and two patients underwent subtotal resection achieved a long-term HB grade I facial nerve function. The long-term facial nerve function of patients underwent complete resection and nerve grafting was no better than HB grade III.1 of the eight patients underwent partial resection experienced tumor regrowth during the follow-up. CONCLUSIONS: Partial or subtotal resection for IAC/CPA FNS may provide an opportunity of retaining excellent facial nerve function. Regular postoperative imaging is helpful to monitor the recurrence.

Evaluations on the stability and bio-compatibility of a new piezoelectric microphone for the implantable middle ear microphone.

BACKGROUND: A new floating piezoelectric microphone (NFPM), driven by the acoustic vibration of the ossicles, has been manufactured in the lab. OBJECTIVES: This study aimed at exploring the stability and bio-compatibility of this NFPM. MATERIALS AND METHODS: The NFPM was implanted into the cat tympanic cavity by clamping it to the handle of the malleus, and then a temporal bone computed tomography (CT) plain scan and three dimensional reconstruction were performed to observe its coupling with the handle of the malleus. After six months of implantation, cats' blood samples were taken for pro-inflammatory factor analysis. Then, the operative cavity was opened to check the NFPM, the auditory ossicular chain and some granulation tissue surrounding the NFPM. RESULTS: The NFPM was firmly clamped to the handle of the malleus of the cats during the six months of implantation. Besides, there was no obvious systemic inflammatory response in the experimental animals. In addition, local proliferation of granulation tissue occurred in the tympanic cavity without hampering the movement of the auditory ossicle,or causing ischemia of the auditory ossicle. CONCLUSION: The NFPM could be implanted in our experimental cats for a long period of time and had good bio-compatibility.

Petrous bone cholesteatoma: our experience of 51 patients with emphasis on cochlea preservation and use of endoscope.

Background: Petrous bone cholesteatoma (PBC) is a rare but local aggressive lesion which can lead to severe complications. Surgery is the mainstay for its treatment. Objectives: To analyse the clinical characteristics and surgical outcomes in a series of patients with PBC, paying special attention to cochlea preservation and use of endoscope. Materials and methods: Retrospective study of 51 patients with PBC who underwent surgery at our centre. Results: Hearing loss (72.5%) and facial paralysis (58.8%) were the two most common symptoms. According to Sanna's classification, supralabyrinthine subtype (51.0%) was the most common subtype, followed by the massive subtype (33.3%). In most patients, PBC was radically removed using subtotal petrosectomy (80.4%). Endoscope was used for assistance in six cases. Various managements of facial nerve were used in different cases. Hearing rehabilitation was not emphasized (44 postoperative dead ear); however, cochlea was preserved as far as possible (45.3%). Recurrence was identified in five patients by MRI with diffusion weighted imaging (DWI) sequence. No recurrence was detected in patients underwent surgery with endoscope assistance. Conclusions and significance: radical excision and functional reconstruction constitute the framework of PBC surgery. Cochlea preservation is critical for possible cochlear implantation in the future. Use of endoscope has the potential to enhance surgical precision and reduce recurrence.

Neurorrhaphy for Facial Reanimation with Interpositional Graft: Outcome in 23 Patients and the Impact of Timing on the Outcome.

OBJECTIVE: Neurorrhaphy with interpositional graft is a practical technique to achieve facial reanimation when the continuity of the facial nerve is interrupted and a large gap between the proximal and distal stump exists. The aim of this study was to report long-term outcomes of neurorrhaphy for facial reanimation with interpositional graft. The roles of some variable factors in the outcome of neurorrhaphy with interpositional graft were also evaluated and compared. METHODS: A retrospective case series from a single tertiary referral center comprised 23 patients with facial nerve interruptions who underwent neurorrhaphy with interpositional graft using either end-to-end anastomosis or end-to-side hypoglossal-facial technique. Preoperative data (age, sex, primary lesion, interval from paralysis to surgery, facial nerve function), intraoperative data (surgical approach, graft and type of neurorrhaphy), and postoperative data (facial nerve function) were collected and analyzed. RESULTS: Mean follow-up time was 26.6 ± 11.9 months. Patients who underwent neurorrhaphy for facial reanimation within 1 year after onset of facial paralysis were more likely to achieve House-Brackmann grade ≤3 compared with patients who underwent neurorrhaphy >1 year after onset of facial paralysis (odds ratio = 23.85, P = 0.04). No other factors were associated with improved outcomes. CONCLUSIONS: Early neurorrhaphy with interpositional graft (≤1 year) for facial reanimation resulted in better final facial nerve function outcomes compared with a delayed procedure.

Mechanisms of Hearing Loss in a Guinea Pig Model of Superior Semicircular Canal Dehiscence.

Defective acoustic transmission in the cochlea is closely related with various auditory and vestibular symptoms. Among them, semicircular canal dehiscence (SCD) with a defective semicircular bone is typical. Currently, the pathogenesis of SCD is usually explained by the third window hypothesis; however, this hypothesis fails to explain the variability in the symptoms and signs experienced by superior SCD (SSCD) patients. We evaluated the mechanism of hearing loss in a guinea pig model of bony dehiscence with various sizes and locations along the superior semicircular canal. Auditory brainstem responses (ABRs) and laser Doppler velocimetry were used to measure hearing loss and vibration changes before and after fenestration, as well as after restorative patching. ABR thresholds at low frequencies (e.g., 1000 Hz) increased after fenestration and decreased back to the normal range after we repaired the defect. Energy leakage from the surgically introduced third window was detected in the range of 300-1500 Hz, accompanied by increased vibration at the umbo, stapes head, and the dehiscence site, while decreased vibration was observed at the round window membrane in the same frequency range. After the patching procedure, the deviant vibrations were recovered. The degree of postfenestration energy leakage was proportional to the size of fenestration and the proximity of the fenestration site to the oval window. These results suggest that the bony fenestration of the superior semicircular canal mimics the hearing loss pattern of patients with SSCD. The decrease in perilymph wave impedance likely accounts for the auditory changes.

A new floating piezoelectric microphone for the implantable middle ear microphone in experimental studies.

CONCLUSIONS: The new floating piezoelectric microphone is feasible for use as an implantable middle ear microphone in a totally implantable cochlear implant. OBJECTIVES: A piezoelectric sensor that is driven by the acoustic vibration of the ossicles is one possible design for a microphone for a totally implantable cochlear implant. Such a new floating piezoelectric microphone has been manufactured in the lab. The purpose of this article was to study the frequency response of the new floating piezoelectric microphone in the intact ossicular chain and to identify whether it is usable and implantable. METHODS: The frequency response of the new floating piezoelectric microphone was analyzed using in vitro testing of fresh cadaveric heads. The microphone, which was designed with an integrated unibody structure to ensure good biocompatibility and capsulation, was attached to the long process of the incus by a titanium clip, or placed in the tympanic cavity and stimulated with pure tones of different frequencies. RESULTS: The new floating piezoelectric microphone can pick up the vibration of the long process of the incus and convert it into electrical signals sensitively and flatly.

Comparative Study on the Roles of the Number of Accelerations and Rotation Angle in the Treatment Maneuvers for Posterior Semicircular Canal Benign Paroxysmal Positional Vertigo.

AIMS: This study aims to investigate the roles of the number of accelerations and rotation angle in the treatment of posterior semicircular canal benign paroxysmal positional vertigo (PC-BPPV). METHODS: We enrolled 344 patients with unilateral PC-BPPV. Of these, 167 patients in the simple-step maneuver (SSM) group were accelerated twice and rotated 120° per step, whereas 177 patients in the multi-step maneuver (MSM) group were accelerated 4 times and rotated 60° per step. Dix-Hallpike (DH) tests were performed to categorize the treatment outcome as follows: 'symptom free' if the result was negative, 'symptom persistent' if the result remained positive after performing the maneuver 3 times or 'canal conversion' if horizontal nystagmus was evoked. RESULTS: Of the patients in the SSM and MSM groups, 78.4 and 91.5% became symptom free, respectively, while canal conversion occurred in 13.8 and 5.1%, respectively (p = 0.003, χ(2) test). The success rate after performing the maneuver once was 57.1% in the MSM and 32.3% in the SSM symptom-free patients (p = 0.001, χ(2) test). One month after the treatment, 22.0 and 9.6% of the SSM and MSM patients had symptom relapse, respectively (p = 0.007, χ(2) test). CONCLUSIONS: More accelerations and a smaller rotation angle improved the effectiveness and efficiency of the repositioning maneuvers and reduced canal conversion.

Effect of Endolymphatic Hydrops on Sound Transmission in Live Guinea Pigs Measured with a Laser Doppler Vibrometer.

Objective. This study aimed at describing the mechanism of hearing loss in low frequency and the different dynamic behavior of the umbo, the stapes head, and the round window membrane (RWM) between normal guinea pigs and those with endolymphatic hydrops (EH), using a laser Doppler vibrometer (LDV). Methods. Cochlear sections were stained with hematoxylin and eosin (HE) to evaluate the hydropic ratio (HR). Auditory brainstem responses (ABR) and whole-mount immunostaining were measured. Displacement of the umbo, stapes head, and RWM in response to ear-canal sound was evaluated using a LDV. Results. Mean HR values in EH model of all the turns are larger than the control group. The ABR threshold of the EH group was significantly higher than that of the control. Strong positive correlation was found between HR at apical turn and ABR threshold elevation at 1000 Hz and at subapical turn and ABR threshold elevation at 2000 Hz. FITC-phalloidin immunostaining of the cochlear basilar membrane in the apical, subapical, and suprabasal turns showed missing and derangement stereocilia of third-row outer hair cells. The umbo, stapes head, and RWM displacement in ears with EH was generally lower than that of normal ears. The EH-induced differences in stapes head and RWM motion were significant at 0.5 kHz. Conclusion. The LDV results suggested that the higher inner ear impedance in EH affected the dynamic behavior of the two opening windows of the cochlea and then reduced the vibration of the ossicular chain by increasing the afterload, resulting in acoustic dysfunction. The vibration reduction mainly occurred at low frequencies, which has related with the morphology changes of the apical and subapical turns in EH model.

The hidden dysfunction of otolithic organs in patients with profound sensorineural hearing loss.

OBJECTIVE: To define the profiles of ocular and cervical vestibular-evoked myogenic potentials (oVEMP and cVEMP, respectively) in patients with profound sensorineural hearing loss (PSHL). METHODS: Twenty-nine patients with PSHL and 20 healthy volunteers were investigated. The patients' medical records were collected and analyzed. The ACS-evoked oVEMPs and cVEMPs and caloric test were tested and analyzed. RESULTS: The oVEMP and cVEMP response rates in the patients with PSHL were 38.9% and 44.4%, respectively, and these values were significantly less than those in the healthy volunteers (both were 100%). Regarding the oVEMPs, significantly higher threshold (p < 0.001) and smaller amplitude (p = 0.022) were observed in the patients. Regarding the cVEMPs, a significant elevation in the threshold (p < 0.001) and a decrease in the amplitude (p = 0.024) were observed, and marked reductions in the P1 (p = 0.002) and N1 latencies (p = 0.001) were observed in the patients. Regarding the caloric test, the ratio of semicircular canal dysfunction in patients with PSHL was significantly higher than that in healthy volunteers (p < 0.001). However, neither the patients nor the doctors noticed balance problems or the loss of otolithic function in the summaries of the medical records of all 29 of the patients. CONCLUSION: The utricular and saccular dysfunction that can be concealed in patients with PSHL can be observed in oVEMPs and cVEMPs. Otolithic function should receive attention in the diagnosis and treatment of PSHL. VEMPs have special value for the observation of hidden dysfunctions of the otolithic organs of patients with PSHL.

Objective and subjective evaluations of the Nurotron Venus cochlear implant system via animal experiments and clinical trials.

CONCLUSION: This study described objective and subjective evaluations of the Nurotron® Venus™ Cochlear Implant System and indicated that this system produced a satisfactory performance. OBJECTIVE: To observe the performance of the Nurotron® Venus™ cochlear implant (CI) system via electrophysiological and psychophysical evaluations. METHODS: A 26-electrode CI system was specially designed. The performance of MRI in animal and cadaveric head experiments, EABR in cats experiment, the correlation between ESRT and C level, and psychophysics evaluations in clinical trials were observed. RESULTS: In the animal and cadaveric head experiments, magnet dislocation could not be prevented in the 1.5 T MRI without removal of the internal magnet. The EABR was clearly elicited in cat experiment. In the clinical trial, the ESRT was strongly correlated with C level (p < 0.001). The human clinical trial involving 57 post-lingually deafened native Mandarin-speaking patients was performed. Residual hearing protection in the implanted ear at each audiometric frequency was observed in 27.5-46.3% patients post-operatively. A pitch ranking test revealed that place pitches were generally ordered from apical to basal electrodes. The recognitions of the perceptions of 301 disyllabic words, environment sounds, disyllabic words, and numerals were significantly better than the pre-operative performance and reached plateaus.

Tumor recurrence and complications of parotidectomy using the marginal mandibular branch as a landmark during the retrograde technique.

PURPOSE: To investigate the recurrence of tumors and morbidity rates of postoperative complications associated with primary parotid pleomorphic adenomas treated with a parotidectomy using the marginal mandibular branch of the facial nerve as a landmark during the retrograde approach. PATIENTS AND METHODS: Our study retrospectively analyzed the clinical data from 71 patients with a primary parotid pleomorphic adenoma who underwent a parotidectomy using the marginal mandibular branch of the facial nerve as a guide during the retrograde approach between November 2003 and August 2012. Three surgical modalities were involved in the study: a partial superficial parotidectomy was performed in 8 cases, a superficial parotidectomy was performed in 54 cases, and a total parotidectomy was performed in 9 cases. The recurrence of tumors and the morbidity rates of postoperative complications, such as transient facial nerve paralysis, permanent facial nerve paralysis, sensory deficiency, Frey syndrome, salivary fistulas, and xerostomia, were investigated. RESULTS: Tumor recurrence occurred in only 1 case. Overall, the morbidity rates for transient facial nerve paralysis, permanent facial nerve paralysis, sensory deficiency, Frey syndrome, and xerostomia were 22.5%, 1.4%, 39.4%, 59.2%, and 8.5%, respectively. No cases developed a salivary fistula. CONCLUSION: The use of the marginal mandibular branch of the facial nerve as a guide during the retrograde approach is a reliable and safe method for dissecting the facial nerve.

Does benign paroxysmal positional vertigo explain age and gender variation in patients with vertigo by mechanical assistance maneuvers?

Benign paroxysmal positional vertigo (BPPV) is one of the most common peripheral vestibular diseases. The aim of this study was to explore the prevalence of BPPV in vertigo patients and the characteristics of BPPV in diagnosis and repositioning using mechanical assistance maneuvers and to analyze and summarize the reasons showing these characteristics. Seven hundred and twenty-six patients with vertigo were enrolled in this study. All patients were inspected by TRV armchair (SYNAPSYS, model TRV, France). BPPV patients were identified by the examination results. The characteristics and results using TRV armchair in diagnosis and treatment of BPPV were compared and analyzed. Of 726 vertigo patients, 209 BPPV patients were diagnosed, including 58 men and 151 women, aged from 16 to 87 (mean 52.90 ± 11.93) years. There were significant differences in the proportion of BPPV in male and female vertigo patients (P = 0.0233), but no differences among all age groups (P = 0.3201). Of 209 BPPV patients, 208 cases were repositioned by TRV armchair and no one appeared to have otolithic debris relocated into another canal in the repositioning procedures. 202 cases (97.12 %) were successful and six cases (2.87 %) were effective. None of them failed. This study suggests that BPPV is one of the most common diseases in the young vertigo patients, just like that in the old ones. Female of the species has predilection for BPPV and the site of predilection is the right posterior semicircular canals (PC-BPPV). The results of repositioning are perfect using mechanical assistance maneuvers.

[Morphological changes associated with low-tone hearing loss in guinea pig models of early endolymphatic hydrops].

The present study was to explore the functional and morphological changes in cochleas of guinea pig models of early endolymphatic hydrops. Thirty albino guinea pigs were randomly divided into three groups: control, 4-week model and 8-week model groups. For each group, n = 10. Model groups were operated on the right ears to result in endolymphatic hydrops with the method of slight destruction of endolymphatic sac and duct from extradural posterior cranial fossa approach, and the animals in control group were sham operated. Electrocochleogram recorded by trans-tympanic approach and auditory brainstem response (ABR) were tested in preoperative model groups, control group, 4-week model group and 8-week model group to assess the hearing changes. Histologic morphometry was used to quantify hydrops by testing scala media area (SMA) ratio. Scanning electron microscope was used to assess the changes of cochlea hair cells. The results showed that the summating potential/compound action potential (SP/AP) ratio of electrocochleogram in 4-week model group (0.33 ± 0.14) and 8-week model group (0.43 ± 0.14) increased significantly, compared with that in control group (0.07 ± 0.06). The maximum SMA ratio in 4-week model group (2.64 ± 0.10) and 8-week model group (3.54 ± 0.13) increased significantly, compared with that in control group (1.06 ± 0.08). The results of maximum SMA ratio correlated with SP/AP ratio of electrocochleogram (r = 0.86). The results of hearing threshold of ABR revealed that the operated ears of model groups were higher than the preoperative results at frequencies of 2 kHz and 4 kHz. And the damage of cochlea hair cells in operated ears occurred in apical and subapical turns. These results suggest the increased SP/AP ratio of electrocochleogram can indicate early endolymphatic hydrops. There is low-tone hearing loss in guinea pig models of early endolymphatic hydrops, and it may be associated with the abnormalities of the stereocilia among the outer hair cells in operated ears which occurs in apical and subapical turns.