Brain Tissue Responses to Guide Cannula Insertion and Replacement of a Microrecording Electrode with a Definitive DBS Electrode

Abstract

The objective is to achieve a better understanding of mechanisms of guide cannula insertion into brains and the replacement of a microrecording electrode with a definitive deep brain stimulation (DBS) electrode during the sub-thalamic nucleus (STN) DBS surgery. Guide cannula insertions are investigated by single-insertion experiments that insert points within labeled cortical surfaces using three cylindrical needles at different insertion velocities. Moreover, the replacement of a microrecording electrode with a definitive DBS electrode is investigated by two-insertion experiments that successively insert points within labeled areas twice using the same needle and absolute insertion depth. The results show that in single-insertion experiments, variations in cortical surface movements and profile patterns of needle axial forces are different at different insertion stages. Needle axial forces at each insertion stage can be modeled by their individual equations. Needles with larger diameters will cause greater dimpling depths/puncture forces. Variations in dimpling depths/puncture forces exhibit undulation with increasing insertion velocities. Dimpling depths positively correlate to puncture forces. In two-insertion experiments, needle axial force and its increasing slope during the second insertion are lower than the first. Actual insertion depth during the second insertion is greater than the first for the same absolute insertion depth. These results can directly guide the mechanical processes of the STN-DBS surgery to minimize insertion traumas and targeting errors.

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