Faculty Bibliography

Long-term synaptic plasticity is a putative mechanism for learning in adults. However, there is little understanding of how synaptic plasticity mechanisms develop or whether their maturation depends on experience. Since inhibitory synapses are particularly malleable to sensory stimulation, long-lasting potentiation of inhibitory synapses was characterized in auditory thalamocortical slices. Intracortical high-frequency electrical stimulation led to a 67% increase in inhibitory synaptic currents. In the absence of stimulation, inhibitory potentiation was induced by a brief exposure to exogenous brain-derived neurotrophic factor (BDNF). BDNF exposure occluded any additional potentiation by high-frequency afferent stimulation, suggesting that BDNF signaling is sufficient to account for inhibitory potentiation. Moreover, inhibitory potentiation was reduced significantly by extracellular application of a BDNF scavenger or by intracellular blockade of BDNF receptor [tropomyosin-related kinase B (TrkB)] signaling. In contrast, glutamatergic or GABAergic antagonists did not prevent the induction of inhibitory potentiation. Since BDNF and TrkB expression are influenced strongly by activity, we predicted that inhibitory potentiation would be diminished by manipulations that decrease central auditory activity, such as hearing loss. Two forms of hearing loss were examined: conductive hearing loss in which the cochleae are not damaged or sensorineural hearing loss in which both cochleae are removed. Both forms of hearing loss were found to reduce significantly the magnitude of inhibitory potentiation. These data indicate that early experience is necessary for the normal development of BDNF-mediated long-lasting inhibitory potentiation, which may be associated with perceptual deficits at later ages

BACKGROUND:The most prevalent long-term complications in patients undergoing laparoscopic adjustable gastric band (LAGB) surgery are symmetric pouch dilation and gastric prolapse (slippage). However, no published data or a reliable model are available to evaluate the actual mechanism of band slippage or how to prevent it. The objective of the present study was to construct an animal model of anterior gastric band prolapse and to use this model to evaluate the effectiveness of various arrangements of gastrogastric sutures and gastric wraps in preventing prolapse. METHODS:The esophagus of male mongrel dogs was accessed through the left chest, and a pressure transducer and an insufflation catheter were introduced. An AP-S Lap-Band (Allergan, Irvine, CA) filled to 10 cm(3) was placed using the pars flaccida technique. A standardized cut of meat was placed into the esophagus to simulate food impaction at a tight LAGB. After the placement of multiple different gastrogastric suture configurations, air was insufflated into the gastric pouch by way of the esophagus. RESULTS:Prolapse, identical to that seen in clinical practice, was reliably reproduced in this model by increased esophageal pressure acting on a LAGB outlet obstruction. In addition, prolapse was reproduced with all gastrogastric configurations that did not secure the anterior gastric wall to within 1.5 cm of the lesser curve. CONCLUSION/CONCLUSIONS:The results of the present study support the theory that prolapse is caused by esophageal peristalsis against an occlusion at the level of the LAGB. In this canine model, gastrogastric sutures encompassing the anterior gastric wall were integral to preventing prolapse.

We present the unique opportunity to correlate videostroboscopic findings with histologic examination. An immunocompromised patient with hoarseness because of ulcerative lesions of both vocal folds of uncertain cause died within a few weeks of initial presentation, and the larynx was donated for postmortem examination. Relevant history, as well as endoscopic and histopathologic findings, is presented

OBJECTIVE: Dehydration challenges can increase the chemical composition of surface fluid overlying vocal fold epithelia (hypertonic surface fluid). The vocal fold epithelium is posited to act as a barrier, shielding the lamina propria from perturbations in the airway lumen. However, the effects of hypertonic surface fluid on the barrier functions of vocal fold epithelia have not been quantified. We, therefore, sought to investigate whether hypertonic surface fluid compromises epithelial barrier function. We examined the effects of hypertonic surface fluid on vocal fold epithelial resistance, paracellular pathway morphology, and tight junction protein integrity. STUDY DESIGN: Ex vivo, between group design. SETTING: Laboratory. METHODS: Porcine vocal folds (n = 24) were exposed to hypertonic or isotonic challenge and examined by electrophysiology, transmission electron microscopy, and Western blot analyses. RESULTS: Hypertonic, but not isotonic, challenge significantly reduced transepithelial resistance. This decrease in resistance was observed immediately after the challenge and was consistent with the appearance of dilated paracellular pathway morphology. However, hypertonic challenge did not alter protein levels of occludin, zona occludens-1, E-cadherin, or beta-catenin. CONCLUSION: Hypertonic surface fluid alters epithelial barrier function in the vocal folds. Specifically, exposure to hypertonic challenges increases epithelial permeability. Given the important role of the vocal fold epithelium in shielding the underlying mucosa from inhaled pathogens and pollutants, our data provide the impetus for future studies on pharmacological treatments aimed at restoring the hydration level and chemical composition of vocal fold surface fluid

Tensor Fascia Lata muscle and musculocutaneous flap has been used in the past for reconstruction of trunk defects and also as a free flap for soft tissue reconstruction elsewhere in the body. Transferring the iliac crest along with the muscle as a free flap has been described earlier, reported for bridging calcaneal defect and small mandibular defects. The use of this flap as a source of free vascularised bone has not been widely practised since these initial few reports. Anatomical studies were carried out to assess the feasibility of using this flap for reconstructing maxillary and other head and neck defects, following which it was successfully used for these indications. The preliminary report describes the flap anatomy, method of harvest and its potential uses in head and neck reconstruction.

OBJECTIVES/HYPOTHESIS:: Medulloblastoma is the most common pediatric malignant tumor of the central nervous system in children. Treatment includes surgical excision, external beam radiation, and multiagent chemotherapy. Otologic sequelae are common and may result from radiation and/or chemotherapy. Profound sensorineural hearing loss (SNHL) is a known complication of neuro-oncologic treatment and may render these patients eligible for cochlear implantation (CI). Issues of CI in this population, including diagnosis, treatment of preoperative middle ear disease, operative and postoperative course, performance data, and long-term tumor surveillance are highlighted and reviewed. STUDY DESIGN:: Retrospective chart review. METHODS:: Three patients treated for pediatric medulloblastoma with surgical resection, postoperative hyperfractioned craniospinal radiotherapy, and multiagent adjuvant chemotherapy who underwent cochlear implantation were identified. Details of neuro-oncologic treatment and associated otologic complications are presented and analyzed. Primary outcome assessment includes treatment of middle ear pathology, perioperative cochlear implant course, and postimplantation performance data. RESULTS:: Each patient required surgical treatment of chronic ear disease 4 to 16 years after chemoradiation. All progressed to profound SNHL and were implanted 8 to 17 years post-neuro-oncologic treatment. There were no intraoperative complications, and full insertion of the cochlear implant electrode array was achieved in each patient. One patient developed postoperative wound dehiscence requiring operative closure. Postimplantation performance data support significant benefit in all patients. CONCLUSIONS:: Patients treated for pediatric medulloblastoma develop otologic sequelae, including profound SNHL, and may require cochlear implantation. Successful management of middle ear and mastoid pathology involves consideration of potential future cochlear implantation. Postoperative performance data supports cochlear implantation in this population. Laryngoscope, 2009

OBJECTIVE: To evaluate changes in lower eyelid position using digital image analysis in patients who have undergone an orbicularis suspension flap combined with blepharoplasty. METHODS: A total of 68 patients (136 eyes) underwent a lower eyelid orbicularis oculi suspension flap combined with blepharoplasty. Digital image analysis was used to standardize each patient's preoperative and postoperative photographs for accurate objective comparison. The photographs were analyzed for lower eyelid position. RESULTS: The mean (SD) preoperative standardized distance from the center of the pupil to the lower eyelid margin (MRD2) in all procedures was 5.53 (0.74) mm. The mean (SD) postoperative standardized MRD2 was 5.22 (1.0) mm. There was a statistically significant difference in MRD2 position such that the postoperative MRD2 position decreased or the lower eyelid position was elevated by an average of 0.31 mm in comparison to the preoperative position (P < .001). CONCLUSIONS: A well-performed suspension flap can elevate the lower eyelid position to a more natural and anatomically appropriate position. By resuspending the ptotic orbicularis muscle, the suspension flap also reinforces the underlying attenuated orbital septum. Such cases may not achieve the optimum level of rejuvenation if isolated lower eyelid blepharoplasty is performed