Risk Assessment of Deep Brain Stimulator Implant Against Incident Lightning Electromagnetic Radiation

Deep brain stimulators (DBSs) have several therapeutic uses, including the treatment of movement and nonmovement disorders, and hence the global market for DBS implants is growing. Nevertheless, research has demonstrated that external electromagnetic fields interact with these implants within the human body, leading to variations in their operational state; several examples of these interactions have already been measured. However, clinical journal case studies have revealed that lightning strikes have notable consequences on active implants that have not yet been measured. Hence this article attempts to quantify the response of DBS implants when exposed to lightning electromagnetic fields (LEMFs). The field penetration into a homogeneous human body in and around the implant is quantified and undesirable variations in the stimulus output of DBS is measured. For a vicinity lightning strike at 10 m, peak value of penetrated electric field strength is computed to be 3.61 kV/cm and a magnetic field strength of 4.81 A/cm. Also an impulse current of 2 mA peak gets coupled along with the real time stimulus current pulse output of DBS, thus causing unbalanced charge injection into human tissue. Further study on various lightning strike distance affirmed an ineffective shielding of the implant and undesirable pick up of LEMF impulse by implant lead electrode.