Electrophysiological and histological abnormality extend beyond the MRI-visible bottom-of-sulcus dysplasia in children
Abstract number :
159
Submission category :
9. Surgery / 9B. Pediatrics
Year :
2020
Submission ID :
2422507
Source :
www.aesnet.org
Presentation date :
12/5/2020 9:07:12 AM
Published date :
Nov 21, 2020, 02:24 AM
Authors :
Puneet Jain, The Hospital for Sick Children, Toronto; Ayako Ochi - Sickkids, Toronto; Carter McInnis - Sickkids, Toronto; Hiroshi Otsubo - Sickkids, Toronto; Carter Snead - Sickkids, Toronto; Elysa Widjaja - Hospital for Sick Children;
Rationale:
Objective: Bottom-of-sulcus dysplasia (BOSD) has been reported to have favorable seizure outcome after resective surgery, but outcome following radiofrequency thermocoagulation was lower than resective surgery, possibly due to involvement of the overlying superficial cortex that was not thermocoagulated. The aim of the study was to determine the extent of electrophysiological and histological abnormality in BOSD.
Method:
We included children with radiologically defined BOSD who underwent resective surgery or MR-guided laser interstitial thermal therapy (MRgLITT), and had at least 1-year follow-up. The clinical, radiological, neurophysiological data, and seizure outcome were extracted from medical records. Invasive video-EEG (IVEEG) was used to assess whether the electrophysiological abnormality was confined to the MRI-visible BOSD, involved the overlying cortex, or adjacent cortex distal to BOSD. Histology of the MRI-visible BOSD along with overlying and adjacent cortex (when resected) was evaluated.
Results:
We identified 43 children with BOSD. The lesion was initially overlooked on MRI in 21 (48.8%) patients. In 39 patients who underwent IVEEG (32 subdural grids and 7 stereo-EEG), the ictal-onset zone extended beyond the MRI-visible BOSD in 26 (67%) patients, with involvement of overlying (9 cases) or adjacent cortex (17 cases). IVEEG confirmed that the MRI-defined BOSD was the ictal onset zone in 35 cases. In one case, the seizures started in the overlying cortex and then spread to the BOSD. In three cases, independent seizures originated from the overlying cortex in addition to the BOSD. Surgical treatments included lesionectomy (15 cases) with resection of overlying (9 cases) or adjacent (14 cases) cortex, lobectomy (1 case), ablation of BOSD (2 cases) and adjacent cortex (2 cases). Pathology in 39 patients who underwent resection showed focal cortical dysplasia (FCD) IIB and IIA in 21 (54%) and 16 (41%) patients respectively, and negative in 2 (5%) cases with incomplete resection of BOSD. The overlying or adjacent resected cortex showed pathological evidence of FCD in 13/39 (33%) patients. Seizure freedom (mean follow up: 3.5 years; range 1-10 years) was achieved in 37 (86%) patients.
Conclusion:
We found that the neurophysiological and histological abnormality could extend beyond the MRI-visible BOSD, highlighting the importance of detailing the extent of neurophysiological abnormality as ablation or resection of MRI-visible BOSD alone may not be adequate to achieve long-term seizure freedom.
Funding:
:None
Surgery