Introduction: During awake craniotomy, cortical stimulation is used to map eloquent areas critical for language, motor and sensory function. In rare patients who undergo a repeat awake craniotomy, intraoperative mapping provides a unique opportunity to study cortical reorganization in the setting of disease.
Methods: We examined a database of 561 brain tumor patients who underwent intraoperative language and sensorimotor mappings during awake craniotomies at our institution. We identified 19 patients who underwent repeat awake craniotomies in which the same brain areas were re-mapped using direct cortical stimulation. Each mapping was performed by the same surgeon and documented by hand-written diagrams, photographs and operative reports.
Results: We compared intraoperative mapping results between initial and repeat craniotomies to determine if language, motor or sensory functions had reorganized between procedures. In 13 of 19 patients (68%), we observed no reorganization of functional areas. In the remaining 6 of 19 patients (32%), functional reorganization occurred. There was no significant difference in the mean inter-procedure intervals (1679 days vs. 1543 days, respectively; p=0.75), nor mean ages (38.7 vs. 39.4 years; p=0.89) between these groups. In 3 of these 6 patients (50%), loss of function occurred, such that eloquent areas lost language or motor function between procedures. In the remaining 3 of these 6 patients (50%), gain of function occurred, such that non-functional areas developed language or motor function between procedures. We did not observe any case in which function shifted from one modality to another.
Conclusions: The adult central nervous system reorganizes motor and language areas in the setting of brain tumors. This surprising plasticity may allow for the preservation of language and sensorimotor function in disease states. In order to avoid causing functional deficits during re-operation, surgeons cannot rely on maps obtained from a previous craniotomy.
Patient Care: This research identifies functional plasticity in neurosurgical patients, and it provides strong evidence that repeat intraoperative mapping is necessary during re-operations in eloquent areas.
Learning Objectives: By the conclusion of this session, participants should be able to 1) Understand the use of intraoperative cortical stimulation in mapping functional brain regions, 2) appreciate the role of central nervous system plasticity in enabling functional reorganization of motor and language systems in the setting of brain tumors, and 3) Recognize the importance of re-mapping during repeat awake craniotomies involving eloquent brain regions.