Abstracts

Rationale: Refractory epilepsy after a perinatal stroke is the major predicting factor for a poor functional outcome. Up to two-thirds of infants with a perinatal arterial ischemic event develop epilepsy and 25% of these cases remain medically refractory.One challenge associated with epilepsy due to perinatal stroke is that seizure onset can be remote from the area of vascular insult and widespread following the early disruption of cortical networks. Furthermore, porencephalic cysts and areas of encephalomalacia can render scalp electroencephalographic (EEG) recordings less sensitive to detect the epileptogenic zones.  Methods: A retrospective review of the Pediatric Epilepsy Database was performed at our institution, comprising 213 children with surgically treated epilepsy between 2006 and 2016. Eight patients satisfied the criteria for this study that included a diagnosis of perinatal stroke and surgery for medically refractory epilepsy. Data collected included patient age and sex, type of vascular injury, seizure semiology, age of seizure onset, associated seizure risk factors, brain magnetic resonance imaging (MRI) findings, scalp EEG results, intracranial EEG data when performed, type of epilepsy surgery and outcome at follow-up.  Results: In the eight patients with evidence of early life vascular injury, six were diagnosed with presumed perinatal stroke and two with neonatal stroke, manifesting seizures within 28 days after birth. Six out of 8 cases were arterial ischemic, with 3 involving one vessel (right middle cerebral artery (MCA) in 1 case, left MCA in 1 case and left internal carotid in 1 case) and 3 involving two vessels (bilateral in all 3). There were 2 cases of hemorrhagic stroke, one with extensive unilateral intraparenchymal involvement and the other one localized to one lobe. The mean age of seizure onset was 2.5 years (range 0 – 7 years) with only two presenting with seizures in the neonatal period. All eight cases had focal seizure semiology. All had failed medical treatment with atleast two anti-epileptics.The mean age at epilepsy surgery was 10 years (range 4 – 11 years). Epilepsy surgeries included functional disconnection (n=2), hemispherectomy (n=2), lobectomy, topectomy or combination of the above. Four patients had a one-stage surgery while four patients had a phase II grid implantation prior to surgery. Six patients (75%) were seizure free (Engel Class I outcome) after their first surgery with a mean follow-up of 5 years post-surgery (range 1-9 years). Amongst these, two were hemispherotomies while the remaining four were more focal procedures. Two patients had an Engel III outcome with one requiring a VNS placement after 12 months, currently at Engel II (case 7).Phase II grids assisted in cases 2 and 5. In cases 1, 4, and 8, magnetoencephalography (MEG) studies were done and enabled the identification of a focal spike volume that subsequently influenced surgical management. All surgical procedures were guided by intraoperative use of electrocorticography.  Conclusions: In this case series, epilepsy surgery in children with seizures secondary to perinatal stroke had an excellent outcome in the majority of cases. Such a favorable outcome was obtained despite extensive lesions on MRI and multifocal epileptiform discharges on scalp EEG. Surgical procedures were guided by an ensemble of presurgical and intraoperative investigations, including invasive EEG, MEG, MRI and ECoG. Six out of the eight surgical procedures were focal resective surgeries despite current trends in practice to consider hemispherectomy with excellent outcomes highlighting the importance of surgery in this age group of patients with epilepsy. Funding: N/A