Research of a surgical approach to reach the GPN for implantation in migraineurs
: A preclinical study

  • Marta Navarro García

Student thesis: Master's Thesis

Abstract

Resection of the Greater Petrosal Nerve (GPN) has been undertaken in the past for cases of severe headache with the purpose of eliminating the vasodilatation and distention of intracranial arteries. This work aims to evaluate the feasibility of nding linear trajectories to access the GPN for electrical stimulation, while avoiding damage to surrounding structures such as the dura mater, semicircular canals and ossicles. Both the anterior and the postauricular approach are explored. The input data for this project are high quality neuroimaging datasets of human temporal bone which were used for 3D reconstruction with a dedicated Software. The data were provided by the University of Cologne. Following the reconstruction of various structures within the middle and inner ear, different surgical pathways were examined, testing also different corridor diameters for the approach (from 2mm down to 1mm). The anterior approach with a diameter of 1.5mm is preferable. This decision was taken with medical experts after analysis of the project's outcome, based on their hands-on experience with surgical procedures on this anatomical region. The safety distance between the canals and the surrounding structures was set at 1mm. However, the conned and complex anatomy of the middle and inner ear make it impossible to maintain this safety distance from both the dura mater and the middle ear cavity. As a result, encroaching into the middle ear cavity was preferred over encroaching into the dura mater. However, this aspect should be addressed carefully from a surgical point of view, to avoid infections of the middle ear and further complications. 3D surgical guides, complementary to the external part of the temporal bone of these subjects were manufactured and employed as surgical guides for performing the drilling procedure. The design of these surgical guides was optimized until obtaining the desired accuracy. Although initially both, Stereolithography (SLA) and Fused Deposition Modelling (FDM) technologies, were employed for manufacturing the templates, the advantages that SLA provides converted it in the only viable one for our purpose. The use of surgical templates to translate planned trajectories into actual practice proved to be effective. Final testing on cadavers confermed the feasibility of accessing the GPN using a linear trajectory approach.
Date of Award2024
Original languageEnglish
SupervisorThomas Haslwanter (Supervisor)

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