D. Bradley Welling

Particulate Matter in the Posterior Semicircular Canal

The pathoetiology of benign paroxysmal positional vertigo (BPPV) is controversial. Particulate matter within the posterior semicircular canal has been identified intraoperatively in patients with BPPV but has also been reported in non‐BPPV patients at the time of translabyrinthine surgery (Parnes LS, McClure JA. Free‐floating endolymphatic particles: a new operative finding during posterior semicircular canal occlusion. Laryngoscope 1992;102:988‐92; Schuknecht HF, Ruby RRF. Cupulolithiasis. Adv Otorhinolaryngol 1973;20:434‐43; Kveton JF, Kashgarian M. Particulate matter within the membranous labyrinth: pathologic or normal? Am J Otol 1994;15:173‐6). The nature of the particulate matter remains unknown.

Acoustic Neuroma: A Cost-Effective Approach

A cost-effective approach to the diagnosis and treatment of acoustic neuromas continues to evolve as diagnostic methods improve. In the past 7 months, since gadolinium-enhanced magnetic resonance imaging (MRI) has become available in our practice, our screening and presurgical workup has changed. The purpose of this article is to outline the current philosophy of the senior authors in relation to acoustic neuroma management on the basis of 72 patients diagnosed from July 1988 to February 1989. With more sensitive diagnostic means, older less sensitive studies may be eliminated from the routine workup, thus maintaining cost-effectiveness while preserving the highest standard of patient care. The body of this article will review our current use of the many available diagnostic options and emphasize a cost-effective approach.

Virtual temporal bone dissection: An interactive surgical simulator

OBJECTIVE: Our goal was to integrate current and emerging technology in virtual systems to provide a temporal bone dissection simulator that allows the user interactivity and realism similar to the cadaver laboratory. STUDY DESIGN: Iterative design and validation of a virtual environment for simulating temporal bone dissection. SETTING: University otolaryngology training program with interdisciplinary interaction in a high-performance computer facility. RESULTS: The system provides visual, force feedback (haptic), and aural interfaces. Unlike previous “fly through” virtual systems, this environment provides a richer emulation of surgical experience. CONCLUSION: The system provides a high level of functional utility and, through initial evaluations, demonstrates promise in adding to traditional training methods. SIGNIFICANCE: The system provides an environment to learn temporal bone surgery in a way similar to the experience with cadaver material where the subject is able to interact with the data without constraints (nondeterministic). Eventually, it may provide the “front end” to a large repository of various temporal bone pathologies that can be accessed through the Internet.

cDNA microarray analysis of vestibular schwannomas.

Background Vestibular schwannomas are known to harbor mutations in the neurofibromatosis type 2 tumor suppressor gene, but the mechanism of the neurofibromatosis type 2 tumor suppressor gene action is not well understood. Identification of genes differentially expressed in normal and diseased tissues through the use of a large-scale, cDNA microarray approach may lead to increased understanding of pathways that lead to tumor formation. Objective The objectives of this study were to evaluate the gene expression profiles in vestibular schwannomas in comparison with normal vestibular nerve tissues and to identify pathways that may be altered in schwannomas. Methods Total RNA was extracted from one normal vestibular nerve and seven vestibular schwannomas. The normal vestibular nerve was from one of the seven patients with small vestibular schwannomas. Radiolabeled cDNA was synthesized and hybridized to cDNA microarray filters that contained 25,920 known genes or expressed sequence tags. Expression profiles were imaged and analyzed. Selected genes that showed three-fold or greater difference in the intensity between the normal nerve and the schwannomas were further examined by real-time polymerase chain reaction and by immunohistochemical staining. Results Forty-two genes (0.2%) were upregulated 3-fold or more in at least 5 of the 7 tumors when the filter images were compared with a normal adjacent vestibular nerve. Among them, osteonectin, an angiogenesis mediator, and RhoB GTPase, which is important in cell signaling, were significantly upregulated in 5 of 7 tumors. Among genes that were downregulated, an apoptosis-related LUCA-15 gene was highly underexpressed in 6 of 7 schwannomas when compared with the normal nerve. Also, ezrin, a relative of the NF2 protein, was significantly downregulated in 5 of 7 tumors. Real-time PCR and immunohistochemistry data support the cDNA microarray findings. Conclusion Our cDNA microarray analysis of schwannomas suggested several interesting and potentially important tumorigenesis pathways associated with vestibular schwannoma formation. Further in vivo study is necessary to define the roles of these identified genes and their potential relationships with the neurofibromatosis type 2 tumor suppressor gene.

Nerve of Origin, Tumor Size, Hearing Preservation, and Facial Nerve Outcomes in 359 Vestibular Schwannoma Resections at a Tertiary Care Academic Center

Objective: To determine nerve of origin, tumor size, hearing preservation rates, and facial nerve outcomes in a retrospective cohort study of patients undergoing translabyrinthine (TL), middle cranial fossa (MCF), and retrosigmoid/suboccipital (SO) approaches to vestibular schwannomas (VS).

Tumor growth and audiometric change in vestibular schwannomas managed conservatively

Objective To prospectively define the correlation between changes in tumor volume and audiometric function in vestibular schwannomas managed conservatively.

Particle repositioning maneuver for benign paroxysmal positional vertigo

The recent demonstration of free‐floating particles in the endolymph of the posterior semicircular canal in patients with benign paroxysmal positional vertigo (BPPV)1 has renewed interest in the physiology and treatment of this entity. The particle repositioning maneuver (PRM) relocates the free‐floating particles from the posterior semicircular canal back into the utricle, relieving the patient of bothersome, often long‐standing vertigo.

Cochlear implantation in the neurofibromatosis type 2 patient: long-term follow-up.

Objective: To evaluate the long‐term hearing outcomes of neurofibromatosis type 2 (NF2) patients with cochlear implants.

Insertional trauma of multichannel cochlear implants

Insertional trauma to the cochlea from three different multichannel cochlear implant electrodes was evaluated in a single‐blind controlled study in fresh human temporal bones. Sixteen fresh human temporal bones were implanted with one of three types of multichannel electrodes (Symbion/InnerAid, Cochlear/Nucleus®, or Storz/UCSF). Seven temporal bones were used as controls where a cochleostomy only was created. The temporal bones were evaluated histologically and cochlear histograms of the trauma were created.

Consensus Recommendations for Current Treatments and Accelerating Clinical Trials for Patients with Neurofibromatosis Type 2

Neurofibromatosis type 2 (NF2) is a tumor suppressor syndrome characterized by bilateral vestibular schwannomas (VS) which often result in deafness despite aggressive management. Meningiomas, ependymomas, and other cranial nerve and peripheral schwannomas are also commonly found in NF2 and collectively lead to major neurologic morbidity and mortality. Traditionally, the overall survival rate in patients with NF2 is estimated to be 38% at 20 years from diagnosis. Hence, there is a desperate need for new, effective therapies. Recent progress in understanding the molecular basis of NF2 related tumors has aided in the identification of potential therapeutic targets and emerging clinical therapies. In June 2010, representatives of the international NF2 research and clinical community convened under the leadership of Drs. D. Gareth Evans (University of Manchester) and Marco Giovannini (House Research Institute) to review the state of NF2 treatment and clinical trials. This manuscript summarizes the expert opinions about current treatments for NF2 associated tumors and recommendations for advancing therapies emerging from that meeting. The development of effective therapies for NF2 associated tumors has the potential for significant clinical advancement not only for patients with NF2 but for thousands of neuro‐oncology patients afflicted with these tumors.