Abstract
The thermal effect of a novel effective electrical stimulation mapping (ESM) technique using an Ojemann's stimulation electrode in open craniotomy areas causes a nondestructive local increase in temperature. Another type of stimulating electrode is a subdural strip, routinely used in intraoperative electrocorticography (ECoG), which applies ESM in a covered subdural area over the motor cortex. ECoG electrode geometry produces a different electrical field, causing a different Joule heat distribution in tissue, one that is impossible to measure in subdural space. Therefore, the previous safety control study of the novel ESM technique needed to be extended to include an assessment of the thermal effect of ECoG strip electrodes. We adapted a previously well-validated numerical model and performed coupled complex electro-thermal transient simulations for short-time (28.4 ms) high-frequency (500 Hz) and hyperintense (peak 100 mA) ESM paradigm. The risk of heat-induced cellular damage was assessed by applying the Arrhenius equation integral on the computed time-dependent spatial distribution of temperature in the brain tissue during ESM stimulation and during the cooldown period. The results showed increases in temperature in the proximity around ECoG electrode discs in a safe range without destructive effects. As opposed to open craniotomy, subdural space is not cooled by the air; hence a higher - but still safe - induced temperature was observed. The presented simulation agrees with the previously published histopathological examination of the stimulated brain tissue, and confirms the safety of the novel ESM technique when applied using ECoG strip electrodes.
Highlights
R ESECTIVE epilepsy surgery is the standard treatment for patients with pharmacoresistant focal epilepsy [1], [2]
The maximum resistance represents the most unfavorable condition concerning the risk of thermal damage
Electrical stimulation mapping (ESM) Temperature Effect 1) Open Craniotomy Scenario: The numerical simulation was divided into three consecutive sub-simulations: initial state, application of ESM, and cooling down
Summary
R ESECTIVE epilepsy surgery is the standard treatment for patients with pharmacoresistant focal epilepsy [1], [2]. The success of epilepsy surgery depends on the possibility to (1) completely remove epileptogenic cortical areas and (2) spare eloquent cortical and subcortical brain structures in order to prevent new postsurgical neurological/cognitive deficits. A recent report from European centers for epilepsy surgery has shown an increasingly complex pathology in epilepsy surgery patients in the past two decades [4], [5]. These circumstances increase the risks of postoperative deficits in children. More precise delineation of eloquent areas plays a crucial role in preventing postsurgical deficits. Electrical stimulation mapping (ESM) of the brain remains the “gold standard” method to identify the motor cortex with certainty
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Schedule a callMore From: IEEE transactions on neural systems and rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society
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