Abstract
Background: To preserve language function, intraoperative functional brain mapping (IFBM) in and near the speech center is essential. Case Report: We present a case of a 73-year-old right-handed woman with colon cancer. She presented with mild speech disturbance. Magnetic resonance imaging revealed a ringed enhancing lesion in the frontal operculum. The preservation of language function was critical; therefore, she underwent awake craniotomy using IFBM. Thus, the speech site was elicited by cortical electrical stimulation at the surface, near the location of the tumor. We made a safe corticotomy on the surface of the lesion and performed the resection of brain metastasis (BM) via a safety corridor. We achieved gross total resection of the BM while preserving the language function. After surgery, she recovered from speech disturbance. She returned to her normal life with improved language function. Conclusion: IFBM is a useful tool to undertake a safe approach via the speech center, avoiding permanent language deficits.
- Language function
- awake craniotomy
- brain metastasis
- intraoperative electrical stimulation mapping
- subcortical metastasis.
Brain metastasis (BM) from extra-cranial cancer is the most common neoplasm among intracranial brain tumors. With the advancement of chemotherapy and radiation therapy for cancer, there are more treatment options for brain metastasis. Stereotactic radiosurgery for small BM is associated with better tumor control and fewer complications (1). For large BM, surgical resection is the only way to obtain urgent cerebral decompression, relieving the effects induced by the tumor, and reducing the intracranial pressure (2).
To preserve language function, IFBM in and near the speech center is mandatory for infiltrating gliomas. An individualized protocol could help neurosurgeons perform IFBM more safely, not only by employing intraoperative motor, sensory, and language tasks but also by selecting additional tasks to map cognitive functions essential for quality of life (3). However, awake craniotomy for BM is adapted to limited cases because most BMs are cortically located and have a much clearer border line compared to the infiltrating glioma. Here, we present a successful surgical case for subcortical BM beneath the speech center, preserving the language function by using IFBM.
Case Report
A 73-year-old right-handed woman with colon cancer was introduced to our department because she was diagnosed with BM identified with speech disturbance. MRI revealed a left frontal enhancing lesion with perifocal edema, suggesting BM (Figure 1). This case was evaluated by a multidisciplinary team, including neurosurgeons, neuroradiologists, and radiation oncologists, to determine the most appropriate therapy. Due to the progressing symptoms and tumor size, surgical resection instead of stereotactic radiosurgery or radiotherapy was recommended. The results of the preoperative language function revealed a mild disturbance in speech expression. Fortunately, the patient could perform tasks like counting and repetition of selected words, but she could not perform picture naming tasks. Then, we planned awake craniotomy for the resection of BM. The patient underwent awake craniotomy with IFBM to identify and preserve the cortical and subcortical functional structures. Our method of awake craniotomy, including the electrical parameters and the intraoperative clinical tasks, has been described in previous studies (4-6). The tumor was delineated using ultrasonography and a neuro-navigation system (Brain Lab, Munich, Germany). After opening the dura mater, the patient was woken up. Starting cortical mapping using an intensity of 3.2 mA, transient speech arrests were elicited in the Broca area (Figure 2, no. 1, 2), and transient disturbances of repetition were elicited in the supramarginal gyrus (Figure 2, no. 3, 4). No other speech disturbances were induced on the surface of the tumor (tumor boundary: A~E) by cortical electrical stimulation. After the completion of this cortical mapping, resection was initiated. When we made a safe corticotomy over the tumor, she was able to do counting and repetition. After the demarcated tumor was exposed, we performed the internal decompression and dissected the surrounding gliosis. The disturbance of repetition was reproducibly elicited at the superior part of the tumor cavity by subcortical electrical stimulation (three errors for three trials) (Figure 3, no. 50). Repetitions were normalized after stopping the electrical stimulations. As this tumor had infiltrated next to the Sylvian fissure, we carefully resected the remnant of the tumor. At the final stage of the awake condition, the patient could perform counting and repetition without any problems.
Preoperative images. Magnetic resonance imaging of the brain showing a left frontal lesion suggesting a brain metastasis with perifocal edema on enhanced images (A, C, and D) and T2-weighted axial image (B).
Intraoperative pictures. Intraoperative photogragh of the surface of the exposed operative field. The tumor location elicited by using neuro-navigation and ultrasonography is marked by letters (A–F). The cortical sites associated with language function detected using intraoperative functional brain mapping (IFBM) are marked by numbers as follows: 1, 2: speech arrest, and 3, 4: repetition disorder. Intraoperative photogragh of the surface after the resection. The subcortical site associated with language function elicited by using IFBM is marked by numbers as follows: 50: repetition disorder.
Postoperative images. Magnetic resonanse imaging of the brain on enhanced images the day after surgery showing the gross total removal (A: without gadolinium, B and C: with gadolinium).
The postoperative language function was evaluated by the same speech therapist, using the same neurological and language examinations as those used preoperatively. The postoperative course was uneventful. She recovered from speech disturbance gradually. Postoperative language assessment, including the naming tasks, demonstrated a significant improvement. A postoperative MRI was performed the day after surgery to evaluate the extent of resection. This postoperative MRI revealed no enhancement of the lesion (Figure 3). Neuropathological examination revealed viable cancer cells compatible with colon cancer. She underwent additional stereotactic radiotherapy for the resected cavity. Eventually, she returned to her normal life with an improvement of speech disturbances. No evidence of recurrence occurred at the same site twelve months after surgery.
Discussion
To avoid postoperative language disorder, IFBM at the cortical and subcortical levels is essential to preserve the patient’s quality of life. It is also very important to consider the “onco-functional balance” between achieving maximum tumor resection and preservation of maximum function (3). Our previous study revealed that awake craniotomy for cavernous angioma is located in the eloquent area. Using IFBM during awake craniotomy can optimize the resection of the subcortical located cavernous angioma using a safety corridor through the normal brain (4).
Treatment for BM includes whole-brain radiotherapy, surgical resection and stereotactic radiosurgery. Stereotactic radiosurgery for smaller BM is the first line option (1). But, for the patients with larger BM, progressing neurological symptoms, and elevated intracranial pressure, surgical resection is the best way to urgently obtain cerebral decompression, relieve the effects induced by the tumor, and rapidly reduce intracranial pressure (2).
For large BM, surgical intervention under image-guided assistance and intraoperative neurophysiological monitoring has become the gold standard of modern neurosurgery (7). However, surgical intervention for BM in and near the eloquent area is still under discussion. Recently, several studies reported that IFBM for BM located in the Rolandic region might contribute to the safe maximum resection and the preservation of sensorimotor function (7, 8). Spena et al. reported an approach to the purely subcortical brain tumor including the BM, glioma, and cavernous angioma with the aid of awake intraoperative electrical stimulation mapping. Cortical and subcortical electrical stimulation was fundamental to adapt the proper surgical corridor to the lesion. According to the results of this study, transient postoperative morbidity was 79.5%, but all patients had recovered to preoperative status (7).
In this case, cortical IFBM under intraoperative language evaluation was very useful to decide the ideal corridor on the surface of the dorsal part of the frontal lobe. After surgery, the patient had significant recovery from speech disturbance. Thus, we propose to consider awake craniotomy for subcortically located BM beneath the speech center in the dominant hemisphere to optimize the extent of resection while preserving language function.
Footnotes
Authors’ Contributions
RM, MK, and KN performed surgery. TM and FN analyzed the clinical course. All Authors discussed the clinical results, critically revised the manuscript, commented on drafts of the manuscript and approved the final manuscript. IN and HN supervised the study.
Conflicts of Interest
The Authors have no conflicts of interest to declare in relation to this study.
- Received December 6, 2021.
- Revision received January 11, 2022.
- Accepted January 12, 2022.
- Copyright © 2022 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.
