Predictability of thermo-lesions using electrodes for deep brain stimulation - an in vitro study.

Background: Typically, electrodes for Deep Brain Stimulation (DBS) are used for chronic stimulation. However, there are conditions where this therapy has to be discontinued. In such cases using the DBS electrodes as a tool for thermo-lesioning (coagulation) could be used for an alternative treatment. The aim of this study was to determine if it is possible to generate coagula with a predictable geometry and to define their dimensions as a function of power and time in an in vitro model (egg white at room temperature). Furthermore, we tested if repetitive (cumulative) coagulation has an impact on the overall form and size of the clot.
Findings: Coagulation-growth was achieved as a function of power and duration of coagulation; reproducible well-formed thermocoagulations could be achieved. When using two adjacent electrodes a power range between 1.25 Watt and 2.00 Watt resulted in homogenous ovoid coagula. After two minutes of coagulation the clots reached a maximum in size and further growth could not be achieved. It was also possible to increase the size of a preformed clot by repetitive coagulation either by increasing the power level or the duration of the coagulation process.
Conclusions: We could show that it is possible to obtain predictable coagula in-vitro when using DBS electrodes for thermocoagulation even though they have not been developed for that specific purpose. However, until in-vivo safety and efficacy of DBS electrodes for ablation purposes is properly assessed, only approved electrodes should be used for brain ablation.