Abstract. Oral squamous cell carcinomas (OSCC) are frequent epithelial malignancies and afflicted with a poor prognosis. The majority of these cancers are treated with surgical resection and local recurrences are predominantly responsible for a fatal outcome. In order to provide a better understanding of the development of these local recurrences after surgical ablation, we developed an orthotopic floor-ofmouth squamous cell carcinoma murine model, in which local recurrences occur at a high frequency (55%, 8 out of 15 mice) within 6-21 days after microsurgical removal of the primary. Expression of the enhanced green fluorescent protein (eGFP) in the cancer cells allows in this new model to confirm complete surgical resection under the microscope and helps to track repopulating primary tumor cells in the local recurrence by optical imaging. In addition the model resembles all typical features of invasive head and neck cancers including the formation of lymph node metastasis and local infiltration. IntroductionHead and neck squamous cell cancer (HNSCC) is the 6th most common cancer in humans and afflicted with a poor prognosis. HNSCCs, that include cancers of the oral cavity (OSCC), paranasal sinuses, pharynx and larynx, account for more than 615,000 cases per year worldwide and for more than 200,000 deaths (1). The most commonly involved site is the oral cavity with squamous cell carcinomas representing 90% of these cancers (2).The overall 5-year survival rate in patients suffering from OSCC has remained around 50% for several decades. Surgical resection is the mainstay of the treatment of these cancers with or without adjuvant radiation therapy. Despite surgical advances in the field the formation of local recurrences remains the major plague of this disease and is correlated with poor prognosis (1). Thus, an animal model to investigate the development of such recurrences after surgery is required that will aid in the understanding of underlying biological mechanisms and the consecutive design of new treatment strategies.Local tumor recurrences consist of host (i.e. fibroblasts, endothelial cells, macrophages, mast cells) and primary regrowing tumor cells (3). The latter cell population is believed to contain tumor stem cells that significantly contribute to the establishment of recurrent disease (3). An animal model that is supposed to aid in the identification and elucidation of biological mechanisms that are underlying the process of local recurrence formation has to allow to separately study these cell populations, particularly the re-growing primary tumor cells.Labeling of cancer cells via the stable expression of bioluminescent or fluorescent markers such as GFP from the jellyfish Aquorea victoria has been used in various animal models (4-16). Besides the advantage of visualizing tumor cells directly and identifying neo-angiogenesis of tumorbearing sites (17,18), GFP has been successfully used for the detection of distant metastases in a large number of animal studies (9,11,15,(19)(20)(21)(22). Moreover, G...

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Superior semicircular canal dehiscence syndrome is a clinical picture with sound and pressure-induced vertigo, autophony, hearing loss and a lowered bone conduction threshold. It is an important differential diagnosis to otosclerosis and patent eustachian tube. Diagnostic investigations include audiometric testing, nystagmus provocation, computed tomography and vestibular evoked myogenic potentials. Surgical repair of the dehiscence represents a curative therapeutic option. We describe the disease symptoms on the basis of a typical case.