Introduction: The dilemma of achieving 'onco-functional balance' in gliomas affecting the motor cortex highlights the importance of functionally-guided resection strategies. Accurate mapping of eloquent areas often requires frequent stimulation, which, however, can lead to side effects such as seizures and postoperative deficits. To enhance the safety of functional mapping, we investigated the cortical spatial alterations in hand movement areas induced by gliomas, and measured the effectiveness of cortical electrical activity for functional mapping.
Methods: We recruited patients with glioma-infiltrated motor cortex (MCG) and individuals with the unaffected motor cortex (Non-MCG) for awake craniotomy. During these procedures, electrocorticography (ECoG) grids were employed to record signals under three conditions: resting state, finger and wrist movements. We then quantified the distances from the positively stimulated sites to the specific anatomical landmarks. Additionally, we analyzed the relationship between the ECoG power features and the stimulation responses.
Results: Cortical layout for finger activity in the MCG group was more dispersed and overlapped, typically clustering near the central sulcus and Sylvian fissure. A robust match between ECoG mapping and the corresponding stimulation responses was observed. Specifically, the area under the curve (AUC) for the Non-MCG group during resting state reached its peak, with Gamma3 at 0.802 (95% CI = 0.729-0.875) and broadband at 0.865 (95% CI = 0.804-0.926). The MCG group displayed the highest AUC during wrist movements, recording Gamma3 at 0.785 (95% CI = 0.719-0.849) and broadband at 0.824 (95% CI = 0.753-0.890).
Conclusion : Glioma infiltration motor cortex disrupts the spatial distribution of the hand activity, complicating intraoperative stimulation mapping. As a novel and reliable approach, ECoG neural activity can complement and guide stimulation, potentially reducing its frequency, minimizing the risk of functional deficits, and achieving a balance between maximal tumor resection and neurological preservation.
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