Mechanism Of Intracranial Electrode Insertion Of Deep Brain Stimulation Using Finite Element Analysis

The success rate of deep brain stimulation surgery largely depends on the proficiency and skill of the surgeon.The lack of puncture theoretical guidance in the operation process and the inability of brain tissue internal perspective make it difficult to study the impact of puncture equipment on brain tissue in reality,so the surgeon needs the guidance of mechanical knowledge.In view of the above problems,this paper carried out simulation on the operation process and studied the interaction between puncture equipment and brain tissue by combining with the actual operation conditions.By referring to the standard CT map of human head and neck,a three-dimensional model of each part of brain tissue was created,and the optimal intracranial puncture path was planned.In this paper,the action form of the anterior/posterior trocar of brain tissue puncturing is analyzed,and the process of brain tissue puncturing is simulated,and the mechanism of brain tissue puncturing is revealed.Anatomic measurements were made on the brain tissue in the puncture path,and the thickness of each part of the brain tissue was obtained.A simplified model of the puncture area of the brain tissue was established and a simulation study was conducted on the trocar insertion,which proved that the process would not affect the central position of the target.The dynamic model of electrode-brain tissue was established,and the process of detecting electrode injection,pulling needle and stimulating electrode injection was simulated.This paper analyzes and summarizes the data and causes of electrode displacements,establishes a static finite element model of stimulating electrode and brain tissue,and simulates the process of electrode displacements.Mimics software mask editing function was used to realize the separation of white matter and gray matter,and the finite element basic model of brain tissue was established.By referring to the neuroanatomical structure,the location of the subthalamic nucleus was found and 3d reconstruction was carried out.The connection between the medial frontal gyrus and the subthalamic nucleus at the beginning of puncture was determined as the optimal puncture path,and the length of the puncture path was 71.11 mm after measurement.The process before and after the trocar puncture of brain tissue was analyzed,and the following conclusions were drawn: the main force of trocar before the brain puncture was the tissue elastic restoring force;The main forces on brain tissue after puncture are cutting force,friction force,and capsule resistance.The process before and after the trocar puncture of brain tissue was analyzed,and the following conclusions were drawn: the main force of trocar before the brain puncture was the tissue elastic restoring force;The main forces on brain tissue after puncture are cutting force,friction force,and capsule resistance.Based on the real experimental data,the failure strain of brain tissue unit was determined to be 1.3.Under this strain failure condition,the penetration depth of brain tissue was the closest to the experimental data.The distribution map of instantaneous stress and displacement of brain tissue puncturing was analyzed,and the maximum stress position of brain tissue appeared around the tip of the needle.In order to study the effect of trocar insertion on the subthalamic nucleus,anatomical measurements were made on different types of brain tissues on the puncture path.The thickness of gray matter layer was 14.69 mm,and the thickness of white matter layer was56.42 mm.Based on the measured data,a simplified model of the puncture area of brain tissue was established and the simulation analysis of the trocar insertion process was carried out.It is proved that the fluctuation effect of puncture produces a small amount of stress and displacement distribution,but the effect and fluctuation effect of trocar insertion does not affect the central position of the subthalamic nucleus.Real brain tissue anatomy structure dynamics model is established,the detection electrodes into the needle,needle extraction process and the stimulating electrode into the process of the simulation,the following conclusions are drawn and data: electrode subthalamic nuclei in direct contact with the compression will have obvious on its stress and displacement change,probe into the needle electrode process of subthalamic nuclei caused by the maximum displacement is 1.49 mm,drop needle phase will have obvious stress and displacement changes of brain tissue,stimulating electrode into the injection process of subthalamic nuclei caused by the maximum displacement is 1.57 mm,tissue rebound after subthalamic nuclei down 0.44 mm compared to the original position.A finite element model of electrode-brain tissue was constructed by using the methodof controlling surface mesh quality indirectly to control volume mesh quality.The data and causes of electrode drop were analyzed and summarized,and the average data of electrode drop was 3.4mm.The finite element model of electrode-brain tissue statics was established,and the boundary conditions of brain tissue were determined according to the normal physiological state of brain tissue.