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Hypothesis Merlin-deficient Schwann cells (MD-SC) and primary human vestibular schwannoma (VS) cells exhibit selective uptake of sodium-fluorescein (SF), allowing for fluorescent detection and improved visualization of tumor cells, when compared with Schwann cells (SC). Background SF is a fluorescent compound used for fluorescence-guided resection of gliomas. The utility of SF for VS surgery has not been assessed. Methods Mouse MD-SCs and rat SCs were cultured on 96-well plates at different cell densities and treated with SF at several drug concentrations and durations. Relative fluorescence units (RFU) were measured using a fluorometer to determine optimal treatment parameters in vitro. Subsequently, a four-point Likert scale for fluorescence visualization of pelleted cells was created and validated. Blinded observers rated SF-treated primary human VS and SC cultures, which were developed from deidentified specimens obtained from live and cadaveric donors, respectively. Results In contrast to SCs that showed low levels of fluorescence, MD-SCs demonstrated dose-dependent increases in RFUs when treated with incremental dosages of SF as well as longer treatment and fluorescent excitation times. In addition, RFUs were higher at greater MD-SC densities. The Likert scale for fluorescence visualization was validated using nine blinded observers and there were excellent inter- and intrarater reliabilities (intraclass coefficients of 0.989 and >0.858, respectively). Using the Likert scale, human VS treated with SF received higher scores than human SCs (p Conclusion Mouse MD-SC and human VS cells demonstrate preferential uptake of SF when compared with normal primary SCs. Observers detected differences in fluorescence using the validated Likert scale. Further investigations into the utility of SF-guidance in VS surgery are warranted.

Hypothesis: Dexamethasone (DXM) protects against radiation-induced loss of auditory hair cells (HCs) in rat organ of Corti (OC) explants by reducing levels of oxidative stress and apoptosis. Background: Radiation-induced sensorineural hearing loss (HL) is progressive, dose-dependent, and irreversible. Currently, there are no preventative therapeutic modalities for radiation-induced HL. DXM is a synthetic steroid that can potentially target many of the pathways involved in radiation-induced ototoxicity. Methods: Whole OC explants were dissected from 3-day-old rat cochleae exposed to specific dosages of single-fraction radiation (0, 2, 5, 10, or 20 Gy), were either untreated or treated with DXM (75, 150, 300 μg/mL), and then cultured for 48 or 96 hours. Confocal microscopy for oxidative stress (CellRox, 48 h) and apoptosis (TUNEL assay, 96 h) and fluorescent microscopy for viable HC counts (fluorescein isothiocyanate-phalloidin, 96 h) were performed. Analysis of variance and Tukey post hoc testing were used for statistical analysis. Results: Radiation exposure initiated dose-dependent losses of inner and outer HCs, predominantly in the basal turns of the OC explants. DXM protected against radiation-induced HC losses in a dose-dependent manner. DXM significantly reduced levels of oxidative stress and apoptosis in radiation-injured OC explants (p Conclusions: Radiation-initiated HC losses were dose-dependent in OC explants. DXM treatment protected explant HCs against radiation-initiated losses by decreasing the levels of oxidative stress and apoptosis. DXM may potentially be a therapeutic modality for preventing radiation-induced HL; further in vivo studies are necessary.

To assess the outcome of cochlear implantation in children with autism spectrum disorder (ASD).Retrospective case review and survey.Tertiary referral center.Children who meet criteria for cochlear implantation and diagnosis of ASD.Receptive and expressive language scores and parental survey data.Fifteen patients with history of ASD and cochlear implantation were analyzed and compared with 15 patients who received cochlear implant and have no other disability. Postoperatively, more than 67% of children with ASD significantly improved their speech perception skills, and 60% significantly improved their speech expression skills, whereas all patients in the control group showed significant improvement in both aspects. The top 3 reported improvements after cochlear implantation were name recognition, response to verbal requests, and enjoyment of music. Of all behavioral aspects, the use of eye contact was the least improved. Survey results in regard to improvements in patient interaction were more subtle when compared with those related to sound and speech perception. The most improved aspects in the ASD patients' lives after cochlear implantation seemed to be attending to other people's requests and conforming to family routines. Of note, awareness of the child's environment is the most highly ranked improvement attributed to the cochlear implant.Cochlear implants are effective and beneficial for hearing impaired members of the ASD population, although development of language may lag behind that of implanted children with no additional disabilities. Significant speech perception and overall behavior improvement are noted.

HYPOTHESIS Dexamethasone (DXM) protects against cisplatin-induced auditory hair cell (HC) loss in rat organ of Corti (OC) explants in vitro by reducing levels of oxidative stress and NADPH-Oxidase-3 (NOX-3). BACKGROUND Intratympanic DXM has demonstrated protective effects against cisplatin-induced hearing loss in a few animal studies and one clinical trial. However, levels of protection with intratympanic DXM vary significantly between studies, which may not be a result of the intrinsic properties of DXM but rather reflect the diffusion of DXM into the cochlea. The molecular mechanisms and degree of DXM protection against cisplatin ototoxicity are currently unknown. METHODS OC explants from 3-day-old rats were cultured with no treatment or various concentrations of cisplatin (2, 5, or 10 μM) and DXM (75, 150, or 300 μg/mL) in vitro. HC viability and TUNEL assay were performed after 72 hours in vitro and levels of oxidative stress and NOX-3 were evaluated with confocal microscopy after 48 hours in vitro. Analysis of variance with Tukey's post hoc testing was performed. RESULTS Cisplatin initiated dose-dependent losses of outer HCs (OHCs) in the basal turns of exposed explants (p

Gentamicin is a widely used antibiotic, which causes hearing loss because of destruction of auditory hair cells. Mannitol has been shown to have cytoprotective properties in the cochlea both in vitro and in vivo. Mannitol has been shown to be safe in concentrations up to 100 mM in organ of Corti explants. It is proposed as an otoprotective agent against gentamicin ototoxicity.Organ of Corti were dissected from P-3 rat pups and cultured under the following conditions for 96 hours: 1) control, 2) gentamicin (10 μM for all hair cell count experiments), 3) gentamicin + mannitol 10 mM, 4) gentamicin + mannitol 50 mM, and 5) gentamicin + mannitol 100 mM. The tissues were then fixed and stained, and hair cells were counted for segments of the apex, middle, and basal turns. Quantitative RT-PCR (qRT-PCR) was performed on organ of Corti explant extracted RNA after 24 hours in vitro: 1) control; 2) gentamicin (100 μM for all gene expression and CellRox experiments); 3) gentamicin +mannitol 100 mM; and 4) mannitol 100 mM for tumor necrosis factor-alpha (TNF-α), TNF-α receptor (TNFR1A), interleukin-1 beta (IL-1β) and cyclooxygenase-2 (COX-2). In vitro examination of oxidative stress was performed for the same test groups at 24 hours using CellRox Deep Red assay.Gentamicin induced loss of both inner hair cells and outer hair cells with increasing severity from apex to middle to basal segments (Pearson r = -0.999 for inner hair cells and -0.972 for outer hair cells). Mannitol demonstrated dose-dependent otoprotection of IHCs and outer hair cells (p0.001 for mannitol at 100 mM). CellRox demonstrated increased oxidative stress induced by gentamicin exposure, and this effect was attenuated by treatment of gentamicin-exposed explants with mannitol (p0.05). TNF-α, IL-1β TNFR1A, and COX-2 mRNA levels were upregulated by gentamicin (p0.05). Mannitol treatment of gentamicin explants downregulated the gene expression of the proinflammatory cytokines, but this difference did not achieve significance. Interestingly, in gentamicin-challenged organ of Corti explants, Mannitol upregulated the expression of TNFR1A, but this increase did not achieve significance (p0.05).Gentamicin ototoxicity is increasingly severe from the apex to basal turn of the cochlea. Treatment with mannitol prevents gentamicin-induced hair cell loss in a dose-dependent manner, protecting both IHCs and outer hair cells. Mannitol appears to act as a free radical scavenger to reduce the cytotoxic effects of gentamicin by reducing the level of oxidative stress.

Mannitol has otoprotective effects against tumor necrosis factor (TNF) α-induced auditory hair cell (HC) loss.Mannitol has been demonstrated to possess cytoprotective effects in several organ systems. Its protective effect on postischemic hearing loss has also been shown. Mannitol's otoprotective mechanism and site of action are at present unknown.Organ of Corti (OC) explants were dissected from 3 day-old rat pups. The safety (nonototoxicity) of mannitol was assessed at 4 different concentrations (1-100 mM). Three experimental arms were designed including: a control group, TNFα group, and TNFα + mannitol group. Cell viability was determined by counts of fluorescein isothiocyanate (FITC) phalloidin stained HC. Immunofluorescence assay of phospho-c-Jun and the proapoptotic mediators, cleaved caspase-3, apoptosis inducing factor (AIF), and endonuclease G (Endo G) were performed.Analysis of HC density confirmed the safety of mannitol at concentration ranges of 1 to 100 mM. The ototoxic effect of TNFα was demonstrated (p0.05). The otoprotective effect of 100 mM mannitol in TNFα-challenged OC explants was also demonstrated (p0.001). Mannitol treatment reduced the high levels of phospho-c-Jun observed in the TNFα-challenged group. AIF cluster formation and EndoG translocation into the nuclei of HCs were also reduced by mannitol treatment.Mannitol significantly reduces the ototoxic effects of TNFα against auditory HC's potentially by inhibiting c-Jun N terminal kinase (JNK) activation pathway and AIF, EndoG nuclear translocation. This local otoprotective effect may have therapeutic implications in inner ear surgery, for example, cochlear implants, protection of residual hearing, as well as implications for postischemic inner ear insults.

To describe the surgical anatomy and clinical outcomes of a technique for securing cochlear implant receiver/stimulators (R/S). Receiver/stimulators are generally secured by drilling a custom-fit seat and suture-retaining holes in the skull. However, rare intracranial complications and R/S migration have been reported with this standard method. Newer R/S designs feature a low profile and larger, rigid flat bottoms in which drilling a seat may be less appropriate. We report a technique for securing the R/S without drilling bone.Anatomic: Forty-eight half-heads were studied. Digital photography and morphometric analysis demonstrated anatomic boundaries of the subpericranial pocket (t-pocket). Clinical: Retrospective series of 227 consecutive Cochlear implant recipients implanted during a 2-year period using either the t-pocket or standard technique. The main outcome measures were rates of R/S migration and intracranial complications. Minimum follow-up was 12 months.The t-pocket is limited anteriorly by dense condensations of pericranium anteriorly at the temporal-parietal suture, posteroinferiorly at the lamdoid suture, and anteroinferiorly by the bony ridge of the squamous suture. One hundred seventy-one subjects were implanted using the t-pocket technique and 56 using the standard technique, with a minimum follow-up of 12 months. There were no cases of migration or intracranial complications in either group.The t-pocket secures the R/S with anatomically consistent strong points of fixation while precluding dural complications. There were no cases of migration or intracranial complication noted. Further trials and device-specific training with this technique are necessary before it is widely adopted.

The progressive loss of hearing that develops after electrode insertion trauma (EIT) can be attenuated by local dexamethasone (DXM) therapy.Hearing loss (HL) that develops after cochlear implant EIT occurs in two stages in laboratory animals, that is, an immediate loss followed by a progressive loss. Direct infusion of DXM into the guinea pig cochlea can attenuate both ototoxin- and noise-induced HL.Auditory-evoked brainstem responses (ABRs) of guinea pigs were measured for 4 frequencies (i.e., 0.5, 1, 4, and 16 kHz) before, immediately after, and more than 30 days post-EIT for experimental (EIT,EIT + artificial perilymph, and EIT + DXM) and for the contralateral unoperated cochleae of each group. An electrode analog of 0.14-mm diameter was inserted through a basal turn cochleostomy for a depth of 3 mm and withdrawn. DXM in artificial perilymph was delivered immediately post-EIT into the scala tympani via a miniosmotic pump for 8 days.The ABR thresholds of EIT animals increased progressively post-EIT. Contralateral unoperated cochleae had no significant changes in ABR thresholds. Immediately post-EIT, that is, Day 0, the DXM-treated animals exhibited a significant HL at 1, 4, and 16 kHz, but this HL was no longer significant by Day 30 compared with contralateral control ears.The results from immediate local treatment of the cochlea with DXM in an animal model of EIT-induced HL suggest a novel therapeutic strategy for hearing conservation by attenuating the progressive HL that can result from the process of electrode array insertion during cochlear implantation.

To better describe the anatomy of the sensory auricular branch of the facial nerve.Clinical experience and the medical literature suggest that the facial nerve supplies sensory fibers to the external auditory canal and pinna. The anatomic distribution of these fibers remains poorly defined.Ten cadaveric temporal bone dissections with photographic documentation, two clinical cases, and histologic examination of a candidate nerve fiber were collected.The anatomic distribution and histologic confirmation of a facial nerve branch coursing through the posterior wall of the external auditory canal is described. Mean (+/-SD) measurements along the mastoid segment of the facial nerve from the short process of the incus and chorda tympani nerve origin to the auricular branch origin were 11.6 +/- 1.4 mm (range 9-13 mm) and 3.9 +/- 3.0 mm (range 0-8 mm), respectively. Sacrifice of this nerve in a patient resulted in posterior external auditory canal and inferior conchal bowl hypesthesia.The anatomy of a facial nerve branch coursing through the external auditory canal is presented. The anatomic and functional findings of this study suggest that this nerve represents an auricular sensory branch. Understanding these anatomic details may help in identifying the main trunk of the facial nerve in surgery, preventing postoperative external auditory canal hypesthesia, as well as understanding the significance of Ramsay-Hunt Syndrome and Hitselberger's Sign.