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Objectives/hypothesis: Pathologic third window lesions, such as superior semicircular canal dehiscence syndrome (SCDS) or large vestibular aqueduct syndrome (LVAS), cause several auditory and vestibular symptoms, which might affect perilymphatic pressure and induce endolymphatic hydrops (EH). In this study, the existence of EH in subjects with SCDS or LVAS was investigated using contrast-enhanced magnetic resonance imaging (MRI)., Study Design: Case series at university hospital., Methods: Seventeen ears from nine subjects who were diagnosed as having SCDS (five ears from three cases) or LVAS (12 ears from six cases) were studied. Ears were evaluated by 3-T MRI performed 4 hours after intravenous injection of gadodiamide hydrate. Imaging data concerning the degree of EH in the cochlea and the vestibule were compared with clinical symptoms and hearing levels for all ears., Results: All ears showed air-bone gaps at low frequencies on pure tone audiometry. None of the subjects with SCDS had episodes of acute sensorineural hearing loss (SNHL) or vestibular symptoms, except for one patient who complained of head vibration induced by loud noise. Conversely, five of six subjects with LVAS had episodes of acute SNHL or vestibular symptoms. Four of five ears with SCDS showed severe EH in the cochlea, and two ears showed mild EH in the vestibule. All ears with LVAS showed mild to severe EH in both the cochlea and vestibule., Conclusions: The present study demonstrated the existence of EH in ears with pathologic third window lesions, which might affect patients' auditory or vestibular symptoms., Level of Evidence: 4 Laryngoscope, 126:1446-1450, 2016., (© 2015 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives: It has been suggested that analyzing the width and amplitude of the summating potential-action potential (SP-AP) waveforms can increase the sensitivity of electrocochleography. The objective of this study was to evaluate the ratio of SP to AP amplitude (SP/AP) and SP-AP waveform width, as well as the AP latency difference to condensation and rarefaction clicks, for the diagnosis of Menière's disease., Study Design: This was a prospective, controlled study., Methods: We used transtympanic electrocochleography to evaluate 21 patients with definite Menière's disease and 19 normal-hearing patients with other cochleovestibular disorders, comparing SP/AP, AP latency difference, and SP-AP waveform widths as well as calculating the diagnostic sensitivity of these parameters., Results: Mean SP-AP waveform width was 1.89 ms in the study group and 1.58 ms in the control group. Mean SP/AP was 0.37 in the study group and 0.22 in the control group. The mean product of SP-AP waveform width and SP/AP was 75.26 ms% in the study group and 34.60 ms% in the control group. Mean AP latency difference was 0.13 ms in the study group and 0.07 ms in the control group. For the parameters evaluated, the differences between the groups were statistically significant. In the study group, the sensitivities for the width of the SP-AP waveform, the SP/AP, and the AP latency difference were 33.3%, 52.4%, and 23.8%, respectively., Conclusions: The use of the parameters evaluated did not increase the sensitivity of the electrocochleography, whether used in isolation or in conjunction with the SP/AP. Determining SP/AP presented the greatest sensitivity.

Objective: The aim of this experimental study was to examine the potential of local recombinant human insulin-like growth factor-1 (rhIGF-1) application through a biodegradable hydrogel for the treatment of cochleae., Methods: A hydrogel immersed with rhIGF-1 was placed on the round window membrane of Sprague-Dawley rats while a hydrogel immersed with physiological saline was applied to control animals. On day 3 after drug application, the animals were exposed to white noise at 120 dB sound pressure level (SPL) for 2 hours. Cochlear function was monitored using measurements of auditory brain stem responses (ABRs) at frequencies of 8, 16, and 32 kHz. The temporal bones were collected 7 or 30 days after noise exposure and the loss of hair cells was quantitatively analyzed., Results: Local rhIGF-1 treatment significantly reduced the elevation of ABR thresholds on days 7 and 30 after noise exposure. Histologic analysis revealed that local rhIGF-1 treatment significantly prohibited the loss of outer hair cells., Conclusions: These findings demonstrate that local IGF-1 application through the biodegradable hydrogel has the potential for protection of cochleae from noise trauma.

Objectives: The vestibular-evoked myogenic potential (VEMP) has shed new light on vestibular testing. A large negative deflection with a 3-ms latency within the auditory brainstem response (ABR) has been reported in some patients with deafness. This negative deflection has been termed the N3 potential and it is assumed to be a vestibular-evoked potential. This study investigated the relationship between the VEMP and the N3 potential., Study Design: Prospective evaluation of the VEMP and the N3 potential in 21 patients., Methods: The oto-neurological tests, including caloric test, hearing sensitivity test, VEMP, and ABR, were performed and data were analyzed., Results: The average hearing threshold ranged from 65 to above 110 dB, which includes 9 (37.5%) totally deaf ears. The N3 potentials were recorded in 10 (41.7%) ears. A normal VEMP was detected in 16 (66.7%) ears. Canal paresis was observed in 11 (45.8%) ears., Conclusions: Both the VEMP and the N3 potential appear to originate from the sacculus, but because the characteristics of these two responses are not identical, additional factors might be involved in the generation of the N3 potential.

Objective: Rotatory tests in the horizontal plane have shown various degrees of vestibulo-ocular reflex (VOR) asymmetry in patients after surgical deafferentation of one labyrinth. The purpose of this work was to characterize dynamic horizontal VOR responses among patients presenting with a unilateral peripheral labyrinthine deficit of nonsurgical origin and to compare results in isolated vestibular loss versus cochleovestibular loss., Study Design: This study included 40 patients who presented with an acute, spontaneous unilateral peripheral labyrinthine lesion. Twenty-two patients had vestibular loss alone (without associated hearing impairment) and 18 presented with a cochleovestibular deficit (sudden hearing loss with vertigo). The majority of these patients were part of a long-term protocol to evaluate vestibular compensation., Methods: All patients underwent both the clockwise test and the counterclockwise rotatory test in the horizontal plane, using brief impulses of moderate intensity. Results were analyzed by a simplified model of vestibular function, allowing a parametric estimation of the response., Results: A weak and transitory horizontal VOR asymmetry was observed in the 22 patients with vestibular loss. However, the 18 patients with cochleovestibular loss demonstrated a more severe and persistent asymmetry., Conclusions: This study revealed a difference in the dynamic characteristics of the horizontal VOR between patients with vestibular loss and those with cochleovestibular loss. Our results support the presence of an extensive labyrinthine lesion in cochleovestibular deficit that involves the otolith organs. The implications of this involvement on the central mechanisms of otolith-canal interaction are discussed.

Objective: To investigate the evolution of cochleovestibular symptoms before, during, and after microvascular decompression (MVD) of the facial nerve in hemifacial spasm., Study Design: Prospective study in patients with hemifacial spasm. Among our 13 patients who underwent MVD of the facial nerve from 1995 to 1997, 6 had associated cochleovestibular disorders confirmed by neurotologic tests., Results: In four of these patients, a concomitant compression of the eighth and facial nerves was found at surgery. Preoperative magnetic resonance angiography studies had shown three cases of this double neurovascular compression. Intraoperative auditory brainstem response monitoring showed that interposition of Teflon between vessel and facial nerve was highly critical to the auditory function. Auditory brainstem response monitoring was used to guide the surgeon during this critical phase. Surgery improved at least one cochleovestibular symptom in each patient., Conclusions: The authors propose two pathophysiologic hypotheses. First, the concomitant facial and cochleo-vestibular symptoms may be due to a hyperactivity of both the facial and vestibular nuclei. According to theories about cryptogenic hemifacial spasm, the origin of this hyperactivity could be an ectopic excitation focus. However, the two nerves may have different sites of ectopic excitation. According to the second hypothesis, a pulsatile compression of the facial nerve may be transmitted to the eighth nerve. This could take place even if only the facial nerve is in contact with a vascular loop.

Objective: Auditory neuropathy is a recently described clinical entity characterized by sensorineural hearing loss in which the auditory evoked potential (ABR) is absent but otoacoustic emissions are present. This suggests a central locus for the associated hearing loss. In this study the results observed in a child with auditory neuropathy who received a cochlear implant are presented and compared with those of a matched group of children who were recipients of implants., Methods: A single-subject, repeated-measures design, evaluating closed-set and open-set word recognition abilities was used to assess the subject and a control group of matched children with implants who had also experienced a progressive sensorineural hearing loss., Results: The subject demonstrated improvements in vowel recognition (82% correct) by 1 year after implantation, which were only slightly lower than the control group. Consonant recognition and open-set word recognition scores were significantly lower., Conclusion: Caution should be exercised when considering cochlear implantation in children with auditory neuropathy. As with conventional hearing aids, less than optimal results may be seen.

Traditional treatment of otosyphilis with penicillin and corticosteroids has achieved hearing improvement; however, selecting which patients with a positive fluorescent treponemal antibody absorption (FTA-ABS) test will benefit from treatment remains a problem. In order to study this problem, 18 patients with cochleovestibular dysfunction of unknown etiology and positive syphilis serology were treated with intravenous penicillin and corticosteroids. In addition, lumbar puncture and human immunodeficiency virus (HIV) testing were performed on all patients. Hearing improved in 5 (31%) of 16 patients, tinnitus decreased in 11 (85%) of 13, and vertigo improved in 6 (86%) of 7. Factors associated with hearing improvement were hearing loss present less than 5 years, fluctuating hearing, and age less than 60. Improvement was unrelated to the severity of the loss or previous therapy. All patients with cerebrospinal fluid abnormalities, including two patients with HIV disease, had subjective improvements. A diagnostic and treatment protocol is presented.

The management of the profoundly deaf child with a cochlear implant poses a special challenge, particularly when total ossification of the cochlea is present. In this setting, insertion of an electrode array into a child's cochlea is often difficult. Our experience supports the feasibility of partial insertion of a multichannel implant into the basal turn of an ossified cochlea. Five children with ossified cochleae who had undergone partial implantation of a multichannel electrode were compared with the performance of matched controls who had full insertion of multichannel implants. No dramatic differences were detected during a 6- to 18-month follow-up period on selected test measures. These preliminary results suggest that active electrode number may exert a limited effect on performance with a cochlear implant. Drilling out the basal turn of an ossified cochlea in conjunction with partial insertion of a multichannel implant appears to be an acceptable surgical and rehabilitational alternative for placement of a cochlear implant prosthesis in children with complete cochlear ossification.

The mechanism leading to hearing impairment in perilymph fistulas was investigated in guinea pigs with perforated round window membranes (RWM) by analyzing alterations of inner ear fluid pressure, changes of auditory function following manipulations to get presumed air bubbles out of the cochlea ("positional audiometry"), and temporal bone sections. The instantaneous loss of normal positive inner ear fluid pressure after RWM perforation had no immediate effect on auditory function. Inner ear pressure was restored 4 days following RWM perforation. "Positional audiometry" was negative in guinea pigs with perforated RWM. All ears in which auditory thresholds had increased had additional iatrogenic lesions at the spiral lamina. Fistulas in the RWM per se do not affect auditory thresholds. The question of the surgical repair of fistulas was not directly addressed; it only can be concluded that there are no direct sequelae of an isolated fistula which induce auditory impairment and which could be prevented by surgical repair of the fistula.

To study the effects of a persistent perilymph fistula on the cochlea, a small cannula was inserted into the scala tympani of the basal turn of cochlea in guinea pigs. A month later, cochlear morphology and blood flow were studied using either histological evaluation or the microsphere surface preparation technique. Some animals showed no cochlear morphologic changes or no cochlear blood-flow reduction, even if tubal patency was maintained and perilymph leakage lasted for 1 month. This suggests that a prolonged perilymph fistula, per se, causes no permanent cochlear damage. However, in some animals, hair cell damage and cochlear blood-flow disorders were observed. These observations and the causes of hearing loss in clinical cases of perilymph fistula were studied.

Ossification of the cochlea following meningitis presents a surgical challenge. Electrode mapping, especially in the young child, is difficult given the uncertainty of electrode contact with viable neural elements. This paper reviews surgical technique and the use of auditory brainstem responses to map the electrodes. A 4-year-old child deafened by meningitis at age 20 months had bilateral cochlear ossification by computed tomography. At surgery, a canal wall-down mastoidectomy and closure of the ear canal were performed. A trough around the modiolus was drilled, and the electrode array was placed in it. Post-operatively, the patient gave aversive or no responses to electrode stimulation. To assess electrode function, auditory brainstem responses to individual electrode activation were obtained under general anesthesia. Functioning electrodes could thus be selected for mapping. The patient now responds well to sound.