Cortical Functional Mapping Under Awake Craniotomy Advantages and Problems

[Objective] We introduce our functional mapping method under awake craniotomy and evaluated the utility, effectiveness, and surgical outcomes. The advantages and problems of intraoperative awake surgery were discussed. [Method] Two patients with glioma were included in this study. Case 1 showed left temporal lesion with clear margin. Case 2 presented the left parietal diffuse lesion. Preoperative functional examinations of Wada test, functional MRI (fMRI), and MEG were performed for the preparation of awake surgery. Preoperative functional data was registered on the Neuro-navigation system. Intraoperative awake functional mapping was made under the propofol anesthesia. Avoiding of their functional area, we removed their lesions under the confirmation of stimulation method. [Results] Both patients underwent awake craniotomy surgery successfully without permanent neurological deficit. Case 1: right handed 26 year-old female. She had the episode of a sudden convulsion attack. MRI showed a large left temporal lesion. During the intraoperative awake stimulation, patient showed sensory aphasia at the posterior part of the superior temporal gyrus. Gross total removal was performed without a post-operative neurological deficit. Case 2: right handed 29 year-old male. He was transferred to our hospital due to sudden generalized seizure. MRI showed diffuse left parietal lesion. He presented partial Gerstmann's syndrome and sensory aphasia. Partial resection was done under an awake craniotomy. He had transient conductive aphasia postoperatively, which was improved within a couple of days. [Conclusions] Intraoperative awake stimulation was effective for the patients who have lesions over the eloquent language areas. This method has the advantage of avoiding the new neurological deficits with the maximum removal of the lesion. The problems of this method were the limitation of the stimulation time, risk of inducing refractory seizures, and strict indications of the patients who should tolerate the stressful examination. In conclusion, intraoperative awake stimulation method is one of the choices for the patients who can understand the advantages and problems of this method