Authors :
Presenting Author: Donald Bearden, PhD, APBB-CN – Emory University/CHOA
Alyssa Ailion, PhD, ABPP-CN – Boston Children's Hospital, Harvard Medical School
Krista Eschbach, MD – University of Colorado Anschutz Medical Campus – Children’s Hospital Colorado
Spriha Pavuluri, MD – Children's Nebraska
Leigh Sepeta, PhD – Children's National
Hua Xie, PhD – Children's National
Rationale:
Corticocortical evoked potentials (CCEPs) observed during mapping with low frequency electrocortical stimulation (ECS) indicate functional interconnectivity among brain networks. However, it is unclear how these CCEPs correlate with functional outcomes following surgery. We present a case series of 14 patients who underwent low-frequency ECS language mapping with stereoelectroencephalography (sEEG) followed by surgical resection or radiofrequency (RF) ablation of language-relevant tissue associated with CCEPs. We investigated whether tissue destruction of regions showing high functional interconnectivity, as indicated by CCEPs, was associated with language outcomes. We hypothesized that resecting a part of the effective language network, identified by CCEPs during low frequency language mapping, would be associated with a decline in language function.
Methods:
We retrospectively reviewed data from the medical records of 14 pediatric patients (Mage=15.36, SD=2.5 years; 6 females; 3 left-hand dominant) who were implanted with SEEG depth electrodes and subsequently underwent low frequency ECS language mapping followed by surgical destruction of their epileptogenic zone (resection=9, RF ablation=4, laser ablation=1). Functional MRI found 13 patients were left-hemisphere language dominant; 1 right-handed patient did not undergo fMRI. Patients were diagnosed with focal epilepsy (7), encephalocele (1), ganglioglioma (1), tuberous sclerosis (1), cavernous malformation (1), encephalomalacia (1), dysembryoplastic neuroepithelial tumor (1), and Rasmussen encephalitis (1). Postsurgical language changes were based on parent/patient reporting (n=9) and neuropsychological testing (n=5).
Results:
Of the 14 patients in this study, 9 (64%) had portions of their putative language areas surgically destroyed and 6 (43%) experienced new language problems following epilepsy surgery/RF ablation. Of these 6 patients, 4 (80%) had CCEPs in multiple language and language-adjacent regions. In contrast, only 2 of the 8 patients (25%) who did not experience new postsurgical language problems showed CCEPs in multiple language and language-adjacent regions and both of these patients had intellectual impairment prior to their surgical/ablative procedure. Furthermore, 5 of the 6 (83%) patients showing new postsurgical language problems had some portion of their left temporal lobe destroyed, whereas only 1 of the 8 patients (13%) with resections in non-temporal brain regions had language decline.
Conclusions:
Our findings suggest that the presence of CCEPs in multiple language and language adjacent regions may indicate key areas of functional language connectivity, such as critical nodes or functional hubs, and resection of these regions was associated with a high risk for postoperative language decline. In particular, patients who underwent resection of multiple regions where CCEPs were seen during mapping and those whose language dominant temporal lobe structures were surgically destroyed were at highest risk for new postsurgical language problems.
Funding: This study is unfunded.