Brain Tissue Imprint

Overview

This exploratory study aims to validate the collection and analysis of brain tissue imprints during the DBS by using a CE marked Medical Device in patients presenting one of the following five disorders: Parkinson's disease (PD), essential tremor (ET), dystonia (DYS), Obsessive compulsive disorder (OCD) and Tourette Syndrome (TS). The Brain Tissue Imprint project is focused on the DBS surgical procedure, which constitutes an appropriate method to collect brain tissue imprints by taking advantage of the direct and transitory contact at the extremity of the dilator with adjacent brain tissue. Indeed, during this step, micro-fragments of brain material spontaneously adhere to the dilator tip. It is this imprinting process that allows to collect what is defined as "brain tissue imprints. This approach is part of the standard surgical procedure of the SCP without major change or complications.

Deep brain stimulation (DBS) has become the standard functional neurosurgery treatment for drug resistant Parkinson's disease (PD) patients. It has also demonstrated its efficacy to treat various movement disorders as well as neurological and psychiatric disorders. The subthalamic nucleus (STN), the globus pallidus internal (GPi) or the ventral intermediate nucleus of the thalamus (VIM) are the major targets of DBS. Access to pathological brain tissue in living PD patients or other neurological diseases is a key issue for the discovery of new therapeutic targets and the development of potential curative therapies. In this context, DBS offers a unique access to the pathological brain. In the standard surgical procedure, to prepare the way for the final electrode, the surgeon uses a dilator that is lowered gently through the cerebral parenchyma up to the target. It has been shown that during this step, brain tissue fragments adhere to the extremity of the dilator. However, the major drawback of the standard dilator lies in the fact that its end is in contact with several brain regions before reaching the targeted nucleus. Therefore, it is difficult to guarantee the origin of the collected tissue micro-fragments. In order to optimize the specificity of the harvested imprints, the investgator will use a dedicated CE marked medical device that consists of a guide tube and a stylet instead of the dilator used in DBS surgical procedure. The objective of this study is to validate brain tissue imprints collection in PD, ET, DYS, OCD and TS. The BTI will be specifically collected from the targeted implantation site corresponding to the STN, the GPi and the VIM. Moreover, the tip of the electrode (and therefore the BTI) often reaches the substantia negra pars compacta (SNpc) because of its proximity with the STN. The ability to perform BTI in the SNpc is of highly interest since it is the structure containing the neurons that degenerate gradually and massively throughout the pathological process of Parkinson's disease.