Faculty Bibliography

HYPOTHESIS: The current hybrid electrode can be inserted without trauma to the temporal bone and, after insertion, assumes a position within the scala tympani near the outer cochlear wall just beneath the basilar membrane. BACKGROUND: Conservation of residual hearing after cochlear implant electrode insertion requires a special insertion technique and an atraumatic short electrode. This allows electroacoustic stimulation in ears with significant residual hearing. METHODS: Human cadaveric temporal bones were implanted with soft surgical technique under fluoroscopic observation. Dehydrated and resin-impregnated bones are dissected. Real-time electrode insertion behavior and electrode position were evaluated. The bones are examined for evidence of insertion-related trauma. RESULTS: No gross trauma was observed in the implanted bones, and the electrode dynamics evaluation revealed smooth scala tympani insertions. CONCLUSION: Atraumatic insertion of the 10-mm hybrid electrode can be accomplished using an appropriate cochleostomy and insertion technique

OBJECTIVE: To determine whether differences of angles between the alar rim and the long axis of the secondary defect in a Zitelli bilobed flap affect alar displacement in a fresh cadaver model. METHODS: In fresh cadaver heads, identical, unilateral 1-cm circular defects were created at the superior alar margin. Three different laterally based bilobed flap templates for reconstruction were used. One template, used on 3 cadavers, had an angle of 60 degrees between the alar rim and the long axis of the secondary defect. Another template, used on 3 cadavers, had an angle of 90 degrees . The last template had an angle of 135 degrees and was used on 2 cadavers. Photographs were taken before the repair and after with the camera and cadaver heads in the same spatial relationship to each other. RESULTS: In the 3 cadavers that had repair using an angle of 60 degrees , all cadavers experienced alar retraction, with a mean displacement of 1.3 mm. This was not a statistically significant change (P = .07). In the defects that had repair using an angle of 90 degrees , there was also no significant alar displacement (P = .72). In the 2 cadavers that underwent repair using an angle of 135 degrees , both ala underwent depression by 1.0 mm. When the differences achieved between the different angles were compared, there was a significant difference in measured distortion between the cadavers that had 90 degrees and 60 degrees vector placement (P = .02). There were no measurable changes to the contralateral maximal nostril distance. CONCLUSIONS: Vector alignment can have an impact on nostril displacement. In bilobed flaps, the axis of the secondary defect may play an important role. This study suggests that secondary defects aligned perpendicular to the nostril have the least amount of alar distortion

We evaluate the effects of adjuvant treatment with the angiogenesis inhibitor Avastin (bevacizumab) on pathological tissue specimens of high-grade glioma. Tissue from five patients before and after treatment with Avastin was subjected to histological evaluation and compared to four control cases of glioma before and after similar treatment protocols not including bevacizumab. Clinical and radiographic data were reviewed. Histological analysis focused on microvessel density and vascular morphology, and expression patterns of vascular endothelial growth factor-A (VEGF-A) and the hematopoietic stem cell, mesenchymal, and cell motility markers CD34, smooth muscle actin, D2-40, and fascin. All patients with a decrease in microvessel density had a radiographic response, whereas no response was seen in the patients with increased microvessel density. Vascular morphology showed apparent 'normalization' after Avastin treatment in two cases, with thin-walled and evenly distributed vessels. VEGF-A expression in tumor cells was increased in two cases and decreased in three and did not correlate with treatment response. There was a trend toward a relative increase of CD34, smooth muscle actin, D2-40, and fascin immunostaining following treatment with Avastin. Specimens from four patients with recurrent malignant gliomas before and after adjuvant treatment (not including bevacizumab) had features dissimilar from our study cases. We conclude that a change in vascular morphology can be observed following antiangiogenic treatment. There seems to be no correlation between VEGF-A expression and clinical parameters. While the phenomena we describe may not be specific to Avastin, they demonstrate the potential of tissue-based analysis for the discovery of clinically relevant treatment response biomarkers

In previous works, the authors showed that using robot-assisted steerable electrode array insertions can significantly reduce the insertion forces compared to non-steerable electrode arrays. In addition to steering the electrode array, it is possible to change its angle of approach with respect to the scala tympani. This paper focuses on determining the relevance of changing the angle of approach of the electrode array by comparing steerable electrode array insertions using a two Degrees-of-Freedom (DoF) robot versus a four DoF robot. Optimal insertion path planning strategies are presented for both two and four DoF insertions. Simulation results and experiments show that the four DoF insertions can improve over two DoF insertions. Moreover, changing the angle of approach can further reduce the insertion forces. The simulation results also provide the workspace requirements for designing a custom parallel robot for robot-assisted cochlear implant surgery

We have shown previously that auditory experience regulates the maturation of excitatory synapses in the auditory cortex (ACx). In this study, we used electron microscopic immunocytochemistry to determine whether the heightened excitability of the ACx following neonatal sensorineural hearing loss (SNHL) also involves pre- or postsynaptic alterations of GABAergic synapses. SNHL was induced in gerbils just prior to the onset of hearing (postnatal day 10). At P17, the gamma-aminobutyri acid type A (GABA(A)) receptor's beta2/3-subunit (GABA(A)beta2/3) clusters residing at plasma membranes in layers 2/3 of ACx was reduced significantly in size (P < 0.05) and number (P < 0.005), whereas the overall number of immunoreactive puncta (intracellular + plasmalemmal) remained unchanged. The reduction of GABA(A)beta2/3 was observed along perikaryal plasma membranes of excitatory neurons but not of GABAergic interneurons. This cell-specific change can contribute to the enhanced excitability of SNHL ACx. Presynaptically, GABAergic axon terminals were significantly larger but less numerous and contained 47% greater density of glutamic acid decarboxylase immunoreactivity (P < 0.05). This suggests that GABA synthesis may be upregulated by a retrograde signal arising from lowered levels of postsynaptic GABA(A)R. Thus, both, the pre- and postsynaptic sides of inhibitory synapses that form upon pyramidal neurons of the ACx are regulated by neonatal auditory experience

Inhibitory neurotransmission is a critical determinant of neuronal network gain and dynamic range, suggesting that network properties are shaped by activity during development. A previous study demonstrated that sensorineural hearing loss (SNHL) in gerbils leads to smaller inhibitory potentials in L2/3 pyramidal neurons in the thalamorecipient auditory cortex, ACx. Here, we explored the mechanisms that account for proper maturation of gamma-amino butyric acid (GABA)ergic transmission. SNHL was induced at postnatal day (P) 10, and whole-cell voltage-clamp recordings were obtained from layer 2/3 pyramidal neurons in thalamocortical slices at P16-19. SNHL led to an increase in the frequency of GABAzine-sensitive (antagonist) spontaneous (s) and miniature (m) inhibitory postsynaptic currents (IPSCs), accompanied by diminished amplitudes and longer durations. Consistent with this, the amplitudes of minimum-evoked IPSCs were also reduced while their durations were longer. The alpha1- and beta2/3 subunit-specific agonists zolpidem and loreclezole increased control but not SNHL sIPSC durations. To test whether SNHL affected the maturation of GABAergic transmission, sIPSCs were recorded at P10. These sIPSCs resembled the long SNHL sIPSCs. Furthermore, zolpidem and loreclezole were ineffective in increasing their durations. Together, these data strongly suggest that the presynaptic release properties and expression of key postsynaptic GABA(A) receptor subunits are coregulated by hearing

PURPOSE: Head and neck neoplasms requiring surgical resection of the mandible can have negative consequences on patient quality of life. For patients with segmental resections, the vascularized fibular free flap and nonvascularized iliac crest are frequently used. The fibula has surpassed the iliac crest in popularity due to the success associated with a vascularized graft; however, there still remain significant advantages with the nonvascularized graft. There has not been a study comparing the quality of life associated with these two methods of mandibular reconstruction. We carried out the following study to compare quality of life of both grafts in an attempt to help guide therapeutic decisions. PATIENTS AND METHODS: Twenty-nine patients at the University of California, San Francisco undergoing mandibular resection with subsequent reconstruction with either a vascularized fibular free flap or nonvascularized iliac crest bone graft were identified. Patient quality of life was assessed with a modified version of the University of Washington Quality of Life Questionnaire, version 4. RESULTS: Eighteen patients responded (10 reconstructed previously with a fibula, 8 with iliac crest reconstructions). Patients with an iliac crest bone graft had significantly better chewing and swallowing scores (P = .04, P = .049 respectively). There was also a trend for better taste (P = .067). When patients with a history of radiation therapy were excluded, differences in chewing and swallowing were not significant (P = .26 and P = .31 respectively), whereas taste was (P = .038). CONCLUSIONS: These findings suggest that reconstruction with the iliac crest had benefits in improved function (chewing, swallowing, and taste) rather than esthetics, donor site morbidity, or psychologic discomfort as was anticipated. However, prior radiation, a relatively frequent therapy in this patient population, presents an important confounding factor. Radiation therapy is difficult to control for without limiting an already scarce patient pool, and bears with it significant morbidity that likely influenced these findings. Further study is warranted to confirm the results and further distinguish the 2 groups

OBJECTIVES: To provide comprehensive temporal trend analysis of 5-year relative survival rates of laryngeal cancer using the Surveillance, Epidemiology, and End Results database; and to expand on prior reports by including inclusion of laryngeal tumor location, stage, age at diagnosis, treatment strategy, and histologic grade. DESIGN: Retrospective cohort analysis using the Surveillance, Epidemiology, and End Results database of the National Cancer Institute. The Surveillance, Epidemiology, and End Results data were used to design 5 cohorts of patients with laryngeal cancer: 1977-1978, 1983-1984, 1989-1990, 1995-1996, and 2001-2002. Five-year survival rates were analyzed according to tumor site, stage, and grade; age at diagnosis; and treatment strategy. The joinpoint regression model was used to assess survival trends and their statistical significance. RESULTS: Among patients with supraglottic cancer, 5-year relative survival rates for distant disease worsened over time while rates for local and regional disease did not change (P = .01 and P > .05, respectively). For localized glottic cancer, survival remained stable from 1977-1978 to 2001-2002. However, patients with regional and distant glottic cancer demonstrated a significant decrease in survival in the past 3 decades (P < .001). This trend was independent of treatment strategy. Finally, the proportion of well-differentiated tumors in patients with regional laryngeal cancer decreased over time (P < .001 for supraglottic and P = .007 for glottic). CONCLUSIONS: A decreasing 5-year survival trend was found among patients with glottic cancer who had regional disease and in all patients with distant disease. Histopathologic trends not previously reported in those with laryngeal cancer seem to parallel those seen in other tobacco-related cancers. These trends may reflect the effect of birth cohorts and implicate the relationship between carcinogenic exposure and host factors, rather than the influence of treatment