Faculty Bibliography

Although sensorineural hearing loss (SNHL) is known to compromise central auditory structure and function, the impact of milder forms of hearing loss on cellular neurophysiology remains mostly undefined. We induced conductive hearing loss (CHL) in developing gerbils, reared the animals for 8-13 d, and subsequently assessed the temporal features of auditory cortex layer 2/3 pyramidal neurons in a thalamocortical brain slice preparation with whole-cell recordings. Repetitive stimulation of the ventral medial geniculate nucleus (MGv) evoked robust short-term depression of the postsynaptic potentials in control neurons, and this depression increased monotonically at higher stimulation frequencies. In contrast, CHL neurons displayed a faster rate of synaptic depression and a smaller asymptotic amplitude. Moreover, the latency of MGv evoked potentials was consistently longer in CHL neurons for all stimulus rates. A separate assessment of spike frequency adaptation in response to trains of injected current pulses revealed that CHL neurons displayed less adaptation compared with controls, although there was an increase in temporal jitter. For each of these properties, nearly identical findings were observed for SNHL neurons. Together, these data show that CHL significantly alters the temporal properties of auditory cortex synapses and spikes, and this may contribute to processing deficits that attend mild to moderate hearing loss

OBJECTIVES: The safety of the Otologics Fully-Implantable MET Ossicular Stimulator was assessed in adult patients with bilateral moderate to severe sensorineural hearing loss. METHODS: Surgical implantation of the ossicular stimulator was performed. A repeated-measure, within-subjects design assessed safety and aided sound field thresholds and speech performances with the subject's own, appropriately fitted, walk-in hearing aid(s) and the Otologics Fully-Implantable MET Ossicular Stimulator. RESULTS: Twenty patients were implanted and activated as part of the Phase I clinical trial. Results demonstrated 10-20 dB of functional gain across audiometric frequencies. Pure tone averages and monaural word recognition scores were slightly better for the walk-in-aided condition, while patient benefit scales favored the postoperative implant-aided conditions. CONCLUSION/SIGNIFICANCE: Although monaural word scores and aided thresholds favored the walk-in-aided condition, preliminary results indicate that the Otologics MET Fully-Implantable Ossicular Stimulator is an alternative to currently available hearing aids in patients with sensorineural hearing loss.

Solitary fibrous tumors are benign neoplasms of mesenchymal origin. They usually arise from the visceral or parietal pleura and peritoneum, although they have been found in many areas throughout the body. We report a case of solitary fibrous tumor of the parapharyngeal space. Microscopically, the tumor contained spindle cells with areas of marked hypercellularity without a definitepattern. Consistent with a benign lesion, there were few mitoses and no necrosis. The tumor cells stained strongly positive for CD34 and vimentin. At the 2-year follow-up, the patient was well and free of local and/or distant disease

Classic rhizomelic chondrodysplasia punctata is a rare, autosomal, recessively inherited disorder that is characterized by proximal shortening of the limbs, punctuate calcifications of the epiphyses, cataracts, developmental delay, and early lethality. A distinctive biochemical profile is characteristic for each of the several defects of peroxisomal metabolism. Recently, cases have been described that were not associated with peroxisomal dysfunction. These cases were found to be secondary to teratogen exposure or maternal conditions. Since 1993, there have been 9 reported cases of neonates with rhizomelic chondrodysplasia punctata who were born to mothers with connective tissue disease. We followed a newborn boy with features suggestive of rhizomelic chondrodysplasia punctata whose biochemical studies failed to demonstrate a defect in either plasmalogen or cholesterol biosynthesis. His mother developed systemic lupus erythematosus 8 months after delivery. This case is compared with the previously reported 9 cases from the literature and is instructive in demonstrating a lesser known effect of maternal autoantibodies on the fetus.

The authors report a novel technique for the treatment of cholesterol granulomas. An extradural middle fossa approach was used to access the granuloma, with drainage through silastic tubes into the sphenoid sinus via the anteromedial triangle between V1 and V2. Cholesterol granulomas occur when the normal aeration and drainage of temporal bone air cells is occluded, resulting in vacuum formation and transudation of blood into the air cells. This process results in anaerobic breakdown of the blood with resulting cholesterol crystal formation and an inflammatory reaction. Traditional treatment of this lesion involves extensive drilling of the temporal bone to drain the granuloma cyst and establish a drainage tract into the middle ear. Such drainage procedures can be time consuming and difficult, and potentially involve structural damage to the inner ear and facial nerve. An extradural middle fossa approach provides easy access to the granuloma and anterior petrous bone entry into the granuloma for resection. Granuloma drainage is then achieved using shunt tubing in the sphenoid sinus via a small hole in the anteromedial triangle between V1 and V2. Five patients with symptomatic cholesterol granuloma were treated without complication using this novel extradural middle fossa approach. One patient required reoperation 1-year postoperatively for cyst regrowth and occlusion of the drainage tube. At the 5-year follow-up examination, no patient reported recurrent symptoms. Extradural middle fossa craniotomy and silastic tube drainage into the sphenoid sinus is a viable alternative method for treatment of cholesterol granuloma.

OBJECTIVE: Common peroneal nerve (CPN) paresis or paralysis presents with weakness of the toe extensors as well as of the ankle dorsiflexors and evertors, causing foot drop and hypesthesia or paresthesia in the CPN distribution. Previous studies have shown associations with weight loss and leg crossing. Although CPN neuropathy has been described in cancer patients, it has not been described in head and neck cancer (HNC) patients specifically. Our objective was to describe a series of patients who developed CPN neuropathy during the course of their disease. MATERIALS AND METHODS: A retrospective review of the charts of patients with HNC and CPN neuropathy who were seen at our institution between 1995 and 2004 was performed. RESULTS: Four HNC patients with CPN neuropathy were identified. All had significant weight loss. One patient became symptomatic before treatment, 2 patients became symptomatic during treatment, and 1 patient developed foot drop 4 years after treatment when his free jejunal flap developed a stricture. Two patients had electrodiagnostic study findings that revealed conduction block at the fibular head and denervation of peroneal innervated muscles. Imaging studies revealed no evidence of metastatic disease in the lumbosacral region. All 4 patients improved after weight gain. CONCLUSIONS: Common peroneal nerve neuropathy may be seen in HNC patients. The CPN may be susceptible in weight loss because of the associated loss of subcutaneous tissue, which cushions the nerve from the fibular head. Consideration should be given to prevention, appropriate neurologic consultation, and patient counseling

BACKGROUND:Recently, balloon catheter (BC) dilatation of paranasal sinus ostia has been introduced. In this procedure, a balloon-tipped catheter is placed across a sinus ostium over a flexible wire under fluoroscopic guidance, and inflation of the balloon enlarges the ostium. Some rhinologists have criticized this procedure for its failure to remove tissue and bone, especially in the setting of sinonasal polyposis. This project seeks to develop strategies for incorporating BC technology into standard functional endoscopic sinus surgery procedures. METHODS:Endoscopic sinus dissection of three human cadaveric heads was performed with conventional instruments supplemented by lacrimal duct BCs (LacriCATH; Quest Medical, Allen, TX). No fluoroscopy was used. Each dissection was videotaped for later review. RESULTS:For frontal recess dissection, these steps were performed under endoscopic visualization: (1) passage of the BC between frontal recess partitions, (2) BC inflation, and (3) removal of fractured frontal recess partitions with conventional instruments. This approach was used successfully in each frontal recess. Under endoscopic visualization, a BC was passed into the sphenoid ostium and inflated; this maneuver successfully dilated each sphenoid ostium. It was not feasible to reliably pass the BC through the natural maxillary ostium. Each BC was inflated to 8 atm for 30 seconds. No evidence of orbital or skull base injury was noted. No fluoroscopy was used. CONCLUSION/CONCLUSIONS:BCs may be used as adjunctive instrumentation for endoscopic sinus dissection without fluoroscopy. This strategy warrants additional technical and clinical development.

BACKGROUND: The management of cerebrospinal fluid (CSF) leaks can be challenging. Acellular dermal grafts derived from human cadavers can be used as a replacement material when autogenous materials are unavailable. Fibrin tissue adhesive (FTA) is a wound support product that has been used for hemostatic and tissue fixation purposes. The combined use of acellular dermis in conjunction with FTA for dural repair remains a subject of study. The aim of this study was to evaluate wound healing and tissue compatibility characteristics of acellular dermal substitute material when used both with and without FTA, for repair of a dural tear in a chinchilla model. METHODS: Forty-nine chinchillas were included in this randomized case-control study. The squamous portion of the temporal bone was removed to expose the tegmen. A 2 x 2 mm dural defect was removed to create an iatrogenic CSF leak. Then, animals were randomly assigned to one of three treatment groups: group 1, acellular dermis alone; group 2, acellular dermis with FTA; group 3, fibrinogen, acellular dermis, and FTA. Surgical sites were examined grossly at 1- and 2-week intervals. Temporal bones were examined histologically. RESULTS: Grossly, groups 2 and 3 had significantly less visible CSF leak and brain herniation noted at both 1- and 2-week intervals when compared with group 1. Histological results confirmed the gross results showing the best seal in group 2 and 3. CONCLUSION: Acellular dermis combined with FTA provided superior support compared with acellular dermis alone in repair of induced dural defects