Article
Intraoperative optical imaging with tactile irritation – a technical note
Intraoperatives Optical Imaging mit sensorischer Reizung – ein technischer Bericht
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Published: | June 4, 2021 |
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Objective: Resection of brain tumors near eloquent regions without causing additional neurological deficits for patients is challenging for the neurosurgeon in charge. Therefore, neuronavigation and intraoperative electrophysiological stimulation are established tools to increase patients’ safety. A novel approach was shown recently with intraoperative optical imaging, to identify functional intact regions of the cortex near the tumor. Although this stimulation is highly accurate, the intraoperative setup is complex, cortex stimulation might cause epileptic seizures and specialized staff is needed. Therefore, we investigated, whether a direct tactile stimulation of different body parts shows also changes in blood flow during intraoperative optical imaging.
Methods: Two patients underwent a tumor resection in general anesthesia of a superficial glioma near the sensory cortex. Intraoperative optical imaging was performed before resection. Patients were stimulated bipolar in the median nerve at the wrist. Afterwards, the hand region, arm region, the abdomen and leg region were brushed with a surgical rubber for tactile irriation. Image data were acquired with a charge-coupled device camera attached via a beam splitter to a surgical microscope. For each stimulation site, image data of a 30s rest period, 30s stimulation period and 85s poststimulus period were acquired from the cortical surface.
Results: The tactile irritation of the hand revealed equal cortical activation compared to bipolar stimulation of the median nerve. Furthermore, a plausible topographic distribution along the sensory cortex during tactile irritation of different body regions was observed, whereby the abdominal stimulation showed no cortical activation. The difficulty of this method remain the motion artifacts during brushing the different body regions and the associated irritation of the skin.
Conclusion: We showed for the first time, that tactile irritation of different skin regions in general anesthesia leads to changes of blood flow during intraoperative optical imaging. With this new method, a patient individualized and simpler intraoperative setting is possible. Further studies are ongoing to standardize this method to enable a broader usage within the neurosurgical society.