title: High-frequency cortical subdural stimulation enhanced plasticity in surgery of a tumor in Broca's area.
abstract: Functional areas located near or within brain gliomas prevent the complete resection of these tumors. It has recently been described that slow tumor invasion promotes neural reorganization, and even topographic plasticity, allowing a staged resection of those tumors. Thus, our aim was to promote plasticity by mimicking the tumor's capability to displace brain function. This proceeded through the production of a 'virtual lesion' in eloquent areas within a tumor using continuous high-frequency cortical electrical stimulation (cHFCS). An anaplastic astrocytoma located in Broca's area progressed in a patient whose lateralization of language to the side of the lesion was demonstrated with functional MRI. After partial tumor resection using awake cortical monitoring, we implanted a subdural grid over the eloquent cortex located within residual tumor. We then applied cHFCS for 25 days, using a frequency of 130 Hz and a pulse width of 1 ms. Stimulus intensity was set to the threshold wherein mild speech disturbance was evident without any other neurological effects. This treatment successfully achieved the displacement of speech functions, and a more radical resection of the tumor was possible in a second surgery. Critically, a reorganization of motor language areas was demonstrated both with functional MRI and cortical stimulation. Furthermore, motor language areas were also identified in the right hemisphere, where previously they were absent. The patient's speech fluency improved both after stimulation and resection. We therefore demonstrate the first evidence of induced topographic plasticity using cHFCS in eloquent areas within a tumor, which allowed for increased tumor removal. Our results open the possibility to induce plasticity before the resection of brain tumors near eloquent areas, in order to increase the extent of resection.
authors.affiliation: Service of Neurosurgery, Institute of Neurosciences, San Carlos University Hospital, Complutense University of Madrid, Madrid, Spain. jabarcia.hcsc@salud.madrid.org
authors.forename: Juan A
authors.initials: JA
authors.lastname: Barcia
authors.forename: Ana
authors.initials: A
authors.lastname: Sanz
authors.forename: Paloma
authors.initials: P
authors.lastname: Balugo
authors.forename: Pedro
authors.initials: P
authors.lastname: Alonso-Lera
authors.forename: Juan Raúl
authors.initials: JR
authors.lastname: Brin
authors.forename: Miguel
authors.initials: M
authors.lastname: Yus
authors.forename: Mercedes
authors.initials: M
authors.lastname: Gonzalez-Hidalgo
authors.forename: Victoria M
authors.initials: VM
authors.lastname: Acedo
authors.forename: Antonio
authors.initials: A
authors.lastname: Oliviero
mesh_terms: D000328:Adult; D001254:Astrocytoma / Q000628:therapy*; D001932:Brain Neoplasms / Q000628:therapy*; D002540:Cerebral Cortex / Q000601:surgery*; D004558:Electric Stimulation / Q000379:methods*; D005625:Frontal Lobe / Q000473:pathology; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D016343:Monitoring, Intraoperative; D009473:Neuronal Plasticity / Q000502:physiology*; D019635:Neurosurgical Procedures / Q000379:methods*; D013060:Speech; D013355:Subdural Space / Q000601:surgery