Resection of Low-Grade Gliomas in the Face Area of the Primary Motor Cortex and Neurological Outcome

SIMPLE SUMMARY: There is growing evidence that the extent of resection of low-grade glioma is directly correlated with patients’ outcomes. Preservation of function must be the other goal in brain tumor surgery. Only little is known about the organization of the face in the primary motor area (M1). New findings emphasize different motor projections to the facial motor nuclei. The aim of this retrospective study was to analyze the impact of tumor resection within the M1 face area on transient and permanent neurological deficits. Based on 12 patients, we were able to demonstrate that tumor resection within the non-dominant face motor cortex might be safe and, even in the dominant hemisphere, is only associated with transient impairment. We believe that this retrospective analysis can help identify eloquent brain areas and can lead to a change in the treatment paradigm for this disease, affecting many patients and informing many physicians worldwide. ABSTRACT: Objective: During surgery on low-grade gliomas (LGG), reliable data relevant to the primary motor cortex (M1) for the face area are lacking. We analyzed the impact of tumor removal within the M1 face area on neurological deficits. Methods: We included LGG patients with resection within the M1 face area between May 2012 and November 2019. The primary endpoint was postoperative facial motor function. Secondary endpoints were postoperative aphasia, dysarthria, and dysphagia. Surgery was performed either with the awake protocol or under anesthesia with continuous dynamic mapping. The alarm criteria were speech arrest or a mapping threshold of 3 mA or less. Resection was completed in five patients. The resection was stopped due to the alarm criteria in three patients and for other reasons (vascular supply, patient performance) in four patients. A total of 66.7% (n = 8) presented with new-onset facial paresis (62.5% left LGG) and 41.7% (n = 5) with aphasia (all left LGG) postoperatively. After one year, all eight patients had recovered from the facial paresis. Tumor removal within the M1 face area was not associated with permanent facial motor deficits.