In vivo metabolic consequences of DBS electrode insertion

What is it about?

Deep brain stimulation (DBS) is a neurosurgery technique widely used in movement disorders, although its mechanism of action remains unclear. In fact, apart from the stimulation itself, the mechanical insertion of the electrode may play a crucial role. Here we aimed to distinguish between the insertional and the DBS effects on brain glucose metabolism. To this end, electrodes were implanted targeting the medial prefrontal cortex in five adult male Wistar rats. Positron Emission Tomography (PET) studies were performed before surgery (D0) and seven (D7) and nine days (D9) after that. DBS was applied during the 18FDG uptake of the D9 study. PET data were analyzed with statistical parametric mapping. We found an electrode insertional effect in cortical areas, while DBS resulted in a more widespread metabolic pattern. The consequences of the simultaneous electrode and DBS factors revealed a combination of both effects. Therefore, the insertion metabolic effects differed from the stimulation ones, which should be considered when assessing DBS protocols.

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Why is it important?

Our study highlights the importance of the design of appropriate protocols, particularly in neuroimaging, emphasizing the value of scanning the same subject with/without DBS, for a full understanding of the DBS mechanism of action and its clinical consequences. This will allow taking advantage of the electrodes and the stimulation consequences in order to optimize the DBS protocols for achieving the desired therapeutic effects.