Search

Objectives Vestibular schwannomas (VS) are intracranial tumors, which are caused by NF2 gene mutations that lead to loss of merlin protein. A treatment for VS is stereotactic radiosurgery, a form of radiation. To better understand the radiobiology of VS and radiation toxicity to adjacent structures, our main objectives were (1) investigate effects of single fraction (SF) radiation on viability, cytotoxicity, and apoptosis in normal Schwann cells (SCs) and merlin-deficient Schwann cells (MD-SCs) in vitro, and (2) analyze expression of double strand DNA breaks (γ-H2AX) and DNA repair protein Rad51 following irradiation. Study Design This is a basic science study. Setting This study is conducted in a research laboratory. Participants Patients did not participate in this study. Main Outcome Measures In irradiated normal SCs and MD-SCs (0–18 Gy), we measured (1) viability, cytotoxicity, and apoptosis using cell-based assays, and (2) percentage of cells with γ-H2AX and Rad51 on immunofluorescence. Results A high percentage of irradiated MD-SCs expressed γ-H2AX, which may explain the dose-dependent losses in viability in rodent and human cell lines. In comparison, the viabilities of normal SCs were only compromised at higher doses of radiation (>12 Gy, human SCs), which may be related to less Rad51 repair. There were no further reductions in viability in human MD-SCs beyond 9 Gy, suggesting that Conclusion The MD-SCs are more susceptible to radiation than normal SCs, in part through differential expression of γ-H2AX and Rad51. Understanding the radiobiology of MD-SCs and normal SCs is important for optimizing radiation protocols to maximize tumor control while limiting radiation toxicity in VS patients.

The SARS-CoV-2 virus and resulting COVID-19 pandemic have significantly impacted surgical procedures of the skull base.In particular, aerosol-generating procedures (AGP) confer a greater risk of surgeons contracting the disease1. AGPs includethe use of electrocautery, open suctioning, and drilling. Temporal bone drilling aerosolizes bone, blood, and mucosa. Thelining of the eustachian tube, middle ear, and mastoid air cells has been shown to harbor multiple respiratory viruses.Incidents of combined neurootology and neurosurgical procedures resulting in infections of surgeons and trainees havebeen reported. Intraoperative exposures may occur even when patients test negative for COVID-19 preoperatively, despiteproper personal protective equipment (PPE). We describe the use of a protective tent to reduce the number of aerosolizedparticles within the operating room. Using a standard c-arm drape ([ Fig. 1 ]), a sterile tent can be created between theoperating field and microscope. The drape is cut in the middle between the two arms. One side has a circumferential rubberband that goes around the patient and irrigation bag, where it is then secured with clamps. Suction tubing and drill wiresare passed beneath this with additional tenting support from a Leyla's retractor on the contralateral side ([ Fig. 2 ]).Surgeons may attach suctions to the integrated smoke evacuator of the Neptune 3 Waste Management System. Thesurgeon accesses the operative site by two small slits that accommodate the forearms, while still allowing access to themicroscope handles ([ Fig. 3 ]). The surgical technician can pass instruments by going beneath the drape, through smallslits, or by the creation of a flap that is closed and secured when the surgeon is actively working. During temporal bonedrilling it has been clear that the generation of smoke, fluids, and other particles is substantial ([ Fig. 4 ]). With consistentuse, we have found that both the surgeon and assistants quickly accommodate to the new set-up. In addition to proper PPE(eye protection and N95 surgical mask), a protective tent that limits the spread of particles during AGPs in skull basesurgery may help decrease transmission of COVID-19 to health care workers.

Background: The Baha implant is increasingly becoming a common form of treatment for individuals with single-sided deafness (SSD). However, evidence-based guidelines for determining candidacy in these patients are not yet established. Purpose: The purpose of this study was to investigate the clinical utility of speech-in-noise testing as a part of the preoperative evaluation of the Baha device in patients with SSD. Research Design: The study design was a prospective cohort of 24 English-speaking adults comparing preoperative results on speech-in-noise measures using the Baha Cordelle II headband stimulator to postoperative results using the patient's external Baha processor. Intervention: Outcome measures included signal-to-noise ratio (SNR) loss as measured by the QuickSIN™ and scores of self-reported disability questionnaires. Results: Wilcoxon signed-rank test resulted in no significant difference between the preoperative and postoperative methods for measuring benefit on listening in noise tasks. Passing Bablok regression analysis showed the preoperative and postoperative results to be statistically equivalent, which suggests that postoperative results can be predicted during preoperative testing. Wilcoxon signed-rank test showed significant improvements in self-reported disability postoperatively. Conclusions: The results support the use of speech-in-noise measures as an accurate predictor of overall benefit in patients with SSD prior to implantation.

Objectives To describe a technique for harvesting larger temporal bone specimens from human cadavers for the training of otolaryngology residents and fellows on the various approaches to the lateral and posterolateral skull base. Design Human cadaveric anatomical study. The calvarium was excised 6 cm above the superior aspect of the ear canal. The brain and cerebellum were carefully removed, and the cranial nerves were cut sharply. Two bony cuts were performed, one in the midsagittal plane and the other in the coronal plane at the level of the optic foramen. Setting Medical school anatomy laboratory. Participants Human cadavers. Main Outcome Measures Anatomical contents of specimens and technical effort required. Results Larger temporal bone specimens containing portions of the parietal, occipital, and sphenoidal bones were consistently obtained using this technique of two bone cuts. All specimens were inspected and contained pertinent surface and skull base landmarks. Conclusions The skull base block method allows for larger temporal bone specimens using a two bone cut technique that is efficient and reproducible. These specimens have the necessary anatomical bony landmarks for studying the complexity, utility, and limitations of lateral and posterolateral approaches to the skull base, important for the education of otolaryngology residents and fellows.

Cochlear implant programming necessitates accurate setting of programming levels, including maximum stimulation levels, of all active electrodes. Frequently, clinical techniques are adequate for setting these levels; however, they are sometimes insufficient (e.g., very young children). In the Nucleus 24, several methods have been suggested for estimation of comfort levels (C levels) from neural response telemetry (NRT); however, many require co-application of clinical measurements. Data was obtained from 21 adult Nucleus 24 recipients to develop reliable predictions of C levels. Multiple regression analysis was performed on NRT threshold, slope of the NRT growth function, age, length of deafness, length of cochlear implant use and electrode impedance to examine predictive ability. Only the NRT threshold and slope of the growth function measures were significant predictors yielding R2 values from 0.391 to 0.769. Results demonstrated that these measures may provide an alternative means of estimating C levels when other clinical measures are unavailable.

Background: To assess and compare an effect of local cochlear ischemia (LCI) and coulomb-controlled iontophoresis (CCI) system stimulation on activity of the cochlea, with monitoring by transtympanic electrocochleography (TT-ECochG). Method and Measures: Young albino rabbits were used in this study. In both experimental models, the same surgical approach through the bulla to visualize the round window (RW) of the cochlea was used. The internal ear canal content was reached via a suboccipital posterior craniotomy. Laser-Doppler cochlear blood flow (LD-CBF) and TT-ECochG (cochlear microphonics [CM] and compound action potentials [CAPs]) were measured using a specially designed probe placed at the RW niche. The TT-ECochG was measured for 4, 8, and 12 KHz tone-bursts. The CCI system was connected to the same probe, and 3 minutes-effective current of no more than 25 microA was delivered. The internal auditory artery (IAA) compression inducing LCI was maintained for 3 minutes. Results: After the first CCI system stimulation, overshoot of CAP and CM amplitudes were observed reaching 140 to 180% of the baseline value, followed by a systemic reduction of both CAP and CM amplitudes for all test frequencies. After 5–10 minutes, CM amplitudes were reduced deeper than CAP amplitudes. The successive CCI stimulations induced regular and fast reduction of TT-EcochG, finally reaching a total or near-total reduction of CM and CAP during 20–30 minutes of observation. In all ears following IAA compression, CBF was reduced to a background level. Simultaneously monitored CM/CAP amplitudes showed systematic decrease, nearly to background values. After reperfusion, CM systematically recovered in the same way for all compressions stabilizing near the baseline. After the first ischemic/reperfusion episode, the CM amplitude for all frequencies was reduced ∼5–10%, whereas the reduction was 10–20% after subsequent episodes. At all frequencies, the CAP began to recover within several minutes and showed serious changes in waveform morphology. Conclusions: Both CCI and LCI affected activity of the cochlea, which was manifested by a CM/CAP amplitude reduction: CCI was found to be a more destructive factor; CM/CAP amplitude reduction for higher frequencies was deeper than for lower frequencies, revealing that the base of the cochlea is more susceptible for damage than the apex.