More specifically, I prefer to use sleep mapping if the tumor does not directly infiltrate the central lobe and its associated white matter tracts but is anatomically within millimeters of these vital structures. This strategy allows mapping for safe resection in nonfunctional peritumoral regions in expectation of radical tumor removal. However, I do use mapping for specific HGGs that do not directly infiltrate the functional areas, but are adjacent to them. Subtotal resection of these HGGs is also associated with postoperative neurological decline and risk of hematoma formation. The use of this technique for resection of high-grade gliomas (HGGs) directly infiltrating the functional cortices and tracts often leads to neurologic morbidity, despite preservation of these functional areas. I use mapping (awake or sleep) primarily for low-grade gliomas affecting the central lobule. Infiltrating tumors associated with the supplementary motor area and internal capsule are also suitable candidates for mapping. I do not use this method for cavernous malformations or metastasis unless mapping information can guide the exact location of the initial corticotomy within the normal cortex to reach the deep lesion. Sensorimotor mapping is typically used for resection of intra-axial lesions and, most frequently, gliomas near or partially infiltrating the sensorimotor cortices and corona radiata. Undoubtedly, sleep mapping is more comfortable for the patient and should be performed if it will provide necessary and reliable information for a safe resection. Using this method, a very focal region of the sensory or motor cortex is depolarized, resulting in uncontrolled motor responses or paresthesias.Ĭortical stimulation mapping can be conducted in two ways: Under anesthesia (sleep mapping) or under conscious sedation (awake mapping). Cortical stimulation is used to circumnavigate the eloquent brain. The presence of functional cortices and white matter tracts of the central lobule (sensorimotor cortices) often limits the extent of resection. Therefore, the safety of glioma surgery near the perirolandic region is crucial for its consideration in the care of the patient. However, the loss of survival advantage is lost when a significant postoperative neurologic deficit such as hemiparesis is incurred. The extent of resection also is associated with time to tumor progression and overall survival.īecause the greatest risk of tumor recurrence occurs within 2 cm of the contrast-enhancing region or tumor borders, the ideal resection strategy should preferably extend slightly beyond these borders. Effective maximal resection leads to seizure control, improvement of symptoms caused by mass effect, a decreased risk of sampling error, and in patients with low-grade gliomas, a decreased risk of malignant transformation. The goal of tumor surgery is to maximize tumor resection while avoiding neurologic deficit.
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