Tese de Doutoramento Medicina, Cirurgia e Morfologia Humana, Neurocirugia 2017 Faculdade de Ciências Médicas, Universidade NOVA de Lisboa

he multidisciplinarity of the surgical teams of Neurosurgery and Otorhinolaryngology involved in the treatment of the cranial base pathology has been fundamental for the progression of the scientific knowledge as well as for the improvement of the patients quality of life (QOL) in all its aspects. Subspecialization in this area is, currently, a reality in many surgical centers, where postgraduate training is a fundamental aspect. The Oto-neurosurgical team at the HEM, in Lisbon, has contributed, since the end of the eighties, to the treatment of the skull base pathology, with particular emphasis on the pathologies shared by these two specialties. Facial nerve injury in the surgery of the cerebellopontine angle (APC) has been difficult to overcome in the last decades. With the work published in 2006 by the Professor Toshiaki Taoka, Radiologist at Nara Medical University Hospital, about the usefulness of Facial Nerve Tractography in the identification of the facial nerve pathway, in the cistern of the cerebellopontine angle, and its application in the surgery of tumors in this anatomical area, came the need to initiate a series of studies that should investigate its possible contribution in the reduction of the surgical morbidity. The programming of this study began in Rotterdam, in the Netherlands, in 2009, with a large team of Neurosurgeons, Otorhinolaryngologists, Radiologists and Neuroradiologists. It also had the participation of three hospitals: the Egas Moniz Hospital (HEM), the Lusíadas Lisboa Hospital (HLL), both in Lisbon, and the Nara Medical University Hospital (NMUH), in Japan. Until 2011, the team developed several study protocols to improve the Diffusion Tensor Tractography for benign tumors located at the cerebellopontine angle. The present study, using a quasi-experimental design, ran from February of 2011 to May of 2015, in which a new image technique in Portugal was developed and refined, with the application of the Diffusion Tensor Tractography in the surgery of benign tumors at the cerebellopontine angle. While aiming to evaluate the contribution of an Oto-Neurosurgical team in the treatment of cranial base pathology, we also proposed to assess the impact of the Facial Nerve Tractography in the surgery of tumors at the cerebellopontine angle with three specific objectives. The first one was to measure the influence of a preoperative Facial Nerve Tractography on the surgical morbidity, with special emphasis on the Schwannomas of the vestibular nerve. The second objective was to classify the impact of Tractography on the surgical time, while the third one expected to weight the effect of this technique in the costs of the surgeries performed. Two groups of patients were used: a control group, consisting of 42 participants who were submitted to the surgery of the Vestibular Schwannomas located at the cerebellopontine angle without the use of Facial Nerve Tractography, and an experimental group of 25 participants submitted to surgery of cerebellopontine angle benign tumors with Facial Nerve Tractography. The results showed that the use of Facial Nerve Tractography performed in the preoperative period had relevant repercussions on facial nerve morbidity, surgical time and costs, with greater effectiveness in the experimental group. It was also shown that Facial Nerve Tractography, as a noninvasive imaging technique, may play a very important role in the future and also be extended to other anatomical regions, such as the spinal cord. The evolution of the equipment and of the software applied to the image, as in the present study, will be relevant by giving a more complete information about the surgical cases.