Intraoperative brain stimulation during awake craniotomy in aphasia prevention

Abstract

Abstract Objective: Surgical treatment of tumors located in close proximity to the eloquent areas carry a risk of postsurgical cognitive deficits, e.g. aphasia, which prevent patients from fully returning to their previous lifestyle. Therefore, in case of the risk of postoperative language deficits, it is important to plan the surgery in a way that will increase the safety of the procedure and spare brain regions crucial for speech functions. The most effective and accurate way of brain mapping in order to prevent damage of the key regions for particular functions is awake craniotomy with intraoperative brain stimulation and neuropsychological assessment. Aim of the study was to present the protocol of language assessment during brain stimulation performed in our center and to analyze the frequency of postoperative verbal deficits. Methods: Forty-six awake craniotomies were performed in patients with lesions of the left dominant hemisphere. In 44 cases with lesion in the frontal (n=14), temporal (n=12), parietal (n=12) and insular areas (6), verbal functions were studied due to the close proximity of tumor to the areas responsible for these processes. The stimulation was performed with a bipolar electrode. Depending on the location of lesions, the following abilities were tested: spontaneous speech, naming, speech understanding, reading, writing and repetition. Results: In all patients, areas responsible for language functions were found using intraoperative brain stimulation. In some cases is resulted in altering the manner, direction, and / or extent of tumor removal. After the surgery 21 (48%) patients had no deficits, 17 (38.5%) had minor short-term deficits (withdrawing spontaneously or with neuropsychological rehabilitation within 2 weeks) and 6 (13.5%) had moderate deficits lasting more than 2 weeks. Conclusion: After awake surgery long-standing aphasia was very rare, therefore it should be considered as effective procedure for removing lesions located close to functionally important brain areas. Keywords: aphasia, awake craniotomy, intraoperative brain stimulation