Intraoperative Thermography in Safety Control of the Electrical Stimulation Mapping Use of high-resolution thermographic camera to control thermal effect of the electrical stimulation: A pilot study
Abstract
The cortical Electric Stimulation Mapping (ESM) procedure is used as a standard approach to localize and continuously monitor function of the eloquent cortex and corticospinal tract during neurosurgical intervention. However, eliciting motor responses using standard ESM paradigm is frequently difficult to young children.
We have thus developed and tested a novel EMS protocol, which uses intense, high frequency and short stimulation pulses. However, the intense stimulation peak-peak current (up to 100 mA) possess the potential risk of tissue damage.
The thermographic measurement was performed in four selected patients in vivo using the high-resolution thermographic camera during resective epilepsy surgery to verify the safety of the novel EMS paradigm. The EMS paradigm was systematically tested for pulse currents gradually increased from 10 to 100 mA.
A moving thermographic picture was stabilized and emissivity was corrected for each pixel to reach the correct temperature interpretation. The results show a local temperature increase in the brain tissue close to the stimulation electrode during the ESM with current intensity above 40 mA.
The 100 mA current caused the maximal temperature increase + 0.4 degrees C. This value added to patient basal temperature is far under safety level 39 degrees C.
Although the temperature increase observed around the stimulating electrode during our ESM paradigm is very low, we are aware that the borderline between electrode and cortex could not be reliably measured. Estimation of the electrical current density and the temperature distribution must be modeled using 3D numerical simulations and compared with the thermographic measurement in future work.