Faculty Bibliography

A potential bottleneck to improving speech perception performance in cochlear implant (CI) users is that some of their electrodes may poorly encode speech information. Several studies have examined the effect of deactivating poorly encoding electrodes on speech perception with mixed results. Many of these studies focused on identifying poorly encoding electrodes by some measure (e.g. electrode discrimination, pitch ordering, threshold, CT-guided, masked modulation detection), but provide inconsistent criteria about which electrodes, and how many, should be deactivated, and without considering how speech information becomes distributed across the electrode array. The present simulation study addresses this issue using computational approaches. Previously validated models were used to generate predictions of speech scores as a function of all possible combinations of active electrodes in a 22-electrode array in three groups of hypothetical subjects representative of relatively better, moderate, and poorer performing CI users. Using high-performance computing, over 500 million predictions were generated. Although deactivation of the poorest encoding electrodes sometimes resulted in predicted benefit, this benefit was significantly less relative to predictions resulting from model-optimized deactivations. This trend persisted when using novel stimuli (i.e. other than those used for optimization) and when using different processing strategies. Optimum electrode deactivation patterns produced an average predicted increase in word scores of 10% with some scores increasing by more than 20%. Optimum electrode deactivation patterns typically included 11 to 19 (out of 22) active electrodes, depending on the performance group. Optimal active electrode combinations were those that maximized discrimination of speech cues, maintaining 80%-100% of the physical span of the array. The present study demonstrates the potential for further improving CI users' speech scores with appropriate selection of active electrodes.

OBJECTIVES:Human papillomavirus-associated (HPV+) oropharyngeal squamous cell carcinoma (OPSCC) is a unique form of head and neck cancer with improved prognosis. We assessed survival for stage I patients with low- or intermediate-risk pathologic features with surgery alone compared with surgery with adjuvant radiation (RT) or chemoradiation (CRT). MATERIALS AND METHODS:We identified patients with stage I HPV+ OPSCC (after restaging with 8th edition staging system) treated with surgery alone, adjuvant RT or CRT in the National Cancer Data Base from 2010 to 2013. We compared survival for low-risk patients (≤1 metastatic lymph nodes with no adverse features) and intermediate-risk patients (2-4 metastatic lymph nodes, microscopic extranodal extension (ENE) or lymphovascular invasion). RESULTS:We examined 1677 patients with median follow-up of 43.9 months. In the intermediate-risk group, 4-year overall survival was 94.0% with surgery alone, 91.5% with adjuvant RT and 92.0% with adjuvant CRT (p = 0.72). There were similar rates of overall survival in the low-risk group. In multivariable models accounting for clinicopathologic differences the dose of adjuvant RT was not associated with mortality. On Cox proportional hazard modeling, adjuvant RT (HR 0.94; CI 0.43-2.08) or CRT (HR 0.96; CI 0.45-2.11) did not significantly improved survival compared with surgery alone in the intermediate-risk group (reference). Similar results were seen in the low-risk group. The composite number of pathologic risk features significantly improved risk stratification. CONCLUSION:We provide observational evidence that adjuvant RT or CRT does not provide a survival benefit for stage I HPV+ OPSCC with low- or intermediate-risk pathologic features.

OBJECTIVE:Given rising scrutiny of healthcare expenditures, understanding intervention costs is increasingly important. This study aimed to compare and characterize costs for vestibular schwannoma (VS) management with microsurgery and radiosurgery to inform practice decisions and appraise cost reduction strategies. METHODS:In conjunction with medical records, internal hospital financial data were used to evaluate costs. Total cost was divided into index costs (costs from arrival through discharge for initial intervention) and follow-up costs (through 36 months) for 317 patients with unilateral VSs undergoing initial management between June 2011 and December 2015. A retrospective matched cohort based on tumor size with 176 patients (88 undergoing each intervention) was created to objectively compare costs between microsurgery and radiosurgery. The full sample of 203 patients treated with resection and 114 patients who underwent radiosurgery was used to evaluate a broad range of outcomes and identify cost contributors within each intervention group. RESULTS:Within the matched cohort, average index costs were significantly higher for microsurgery (100% by definition, because costs are presented as a percentage of the average index cost for the matched microsurgery group; 95% CI 93-107) compared to radiosurgery (38%, 95% CI 38-39). Microsurgery had higher average follow-up costs (1.6% per month, 95% CI 0.8%-2.4%) compared to radiosurgery (0.5% per month, 95% CI 0.4%-0.7%), largely due to costs incurred in the initial months after resection. A major contributor to total cost and cost variability for both resection and radiosurgery was the need for additional interventions in the follow-up period, which were necessary due to complications or persistent functional deficits. Although tumor size was not associated with increased total costs for radiosurgery, linear regression analysis demonstrated that, for patients who underwent microsurgery, each centimeter increase in tumor maximum diameter resulted in an estimated increase in total cost of 50.2% of the average index cost of microsurgery (95% CI 34.6%-65.7%) (p < 0.001, R2 = 0.17). There were no cost differences associated with the proportion of inpatient days in the ICU or with specific surgical approach for patients who underwent resection. CONCLUSIONS:This study is the largest assessment to date based on internal cost data comparing VS management with microsurgery and radiosurgery. Both index and follow-up costs are significantly higher when tumors were managed with resection compared to radiosurgery. Larger tumors were associated with increased resection costs, highlighting the incremental costs associated with observation as the initial management.

Oxytocin is an important neuromodulator in the mammalian brain that increases information salience and circuit plasticity, but its signaling mechanisms and circuit effect are not fully understood. Here we report robust oxytocinergic modulation of intrinsic properties and circuit operations in hippocampal area CA2, a region of emerging importance for hippocampal function and social behavior. Upon oxytocin receptor activation, CA2 pyramidal cells depolarize and fire bursts of action potentials, a consequence of phospholipase C signaling to modify two separate voltage-dependent ionic processes. A reduction of potassium current carried by KCNQ-based M channels depolarizes the cell; protein kinase C activity attenuates spike rate of rise and overshoot, dampening after-hyperpolarizations. These actions, in concert with activation of fast-spiking interneurons, promote repetitive firing and CA2 bursting; bursting then governs short-term plasticity of CA2 synaptic transmission onto CA1 and, thus, efficacy of information transfer in the hippocampal network.

OBJECTIVE It is common for a medical disorder to be managed or researched by individuals who work within different specialties. It is known that both neurosurgeons and neurotologists manage vestibular schwannoma (VS) patients. While overlap in specialty focus has the potential to stimulate multidisciplinary collaboration and innovative thinking, there is a risk of specialties forming closed-communication loops, called knowledge silos, which may inhibit knowledge diffusion. This study quantitatively assessed knowledge sharing between neurosurgery and otolaryngology on the subject of VS. METHODS A broad Web of Science search was used to download details for 4439 articles related to VS through 2016. The publishing journal's specialty and the authors' specialties (based on author department) were determined for available articles. All 114,647 of the article references were categorized by journal specialty. The prevalence of several VS topics was assessed using keyword searches of titles. RESULTS For articles written by neurosurgeons, 44.0% of citations were from neurosurgery journal articles and 23.4% were from otolaryngology journals. The citations of otolaryngology authors included 11.6% neurosurgery journals and 56.5% otolaryngology journals. Both author specialty and journal specialty led to more citations of the same specialty, though author specialty had the largest effect. Comparing the specialties' literature, several VS topics had significantly different levels of coverage, including radiosurgery and hearing topics. Despite the availability of the Internet, there has been no change in the proportions of references for either specialty since 1997 (the year PubMed became publicly available). CONCLUSIONS Partial knowledge silos are observed between neurosurgery and otolaryngology on the topic of VS, based on the peer-reviewed literature. The increase in access provided by the Internet and searchable online databases has not decreased specialty reference bias. These findings offer lessons to improve cross-specialty collaboration, physician learning, and consensus building.

BACKGROUND:This multicenter, retrospective review documents the initial experience using the Flex system for transoral surgery in 2 United States academic centers. METHODS:All patients who underwent transoral robotic surgery using the Medrobotics Flex Robotic System (Raynham, MA) between September 2015 and May 2017 were reviewed. Rates of successful surgery and complications were evaluated. RESULTS:Thirty-six men and 32 women were enrolled in the study. The average age was 55.6 years (range 17-82 years). The Flex system was used successfully in surgery of the tongue base, the palatine tonsils, the supraglottis, the glottis, the hypopharynx, the oral tongue, and the soft palate. Only 6 cases (7.6%) required readmission after discharge. There were no intraoperative or immediate postoperative complications, with no cases of intraoperative hemorrhage. CONCLUSION/CONCLUSIONS:To the best of our knowledge, this is the first study in the United States evaluating the use of the Flex system to safely resect lesions in the oral cavity, larynx, and pharynx.