Abstracts

The aim of this study is to assess clinical outcome of hemispherotomy in children with malformation of cortical development (MCD) in terms of seizure outcome, follow-up MRI, and psychomotor development. Among 48 hemispherotomy procedures, a series of 37 pediatric MCD cases followed up for [gt]1 year postoperatively was the subject of the study. Twenty cases were hemimegalencephaly (HM) and others were hemispheric cortical dysplasia (HCD). Median age at surgery was 29 months. Clinical outcome was assessed in terms of seizure outcome, MRI, and developmental quotient (DQ) at 6, 12 months, and every one year thereafter. To evaluate MRI findings, we specifically focused on 1) the completeness of disconnection of the corpus callosum (CC) and cortical projection fibers (PF), 2) internal or external hydrocephalus, 3) morphological development of contralateral hemisphere. Clinical outome was analyzed in terms of comparison of surgical procedures as well. CLINICAL OUTCOME. Seizure outcome at the final evaluation was 58.8/11.8/29.4/0% in HCD and 36.8/10.5/47.4/5.3% in HM (Engel Class I/II/III/IV). It was positively correlated with postoperative psychomotor development and with morphological development of the contralateral hemisphere. In Class I/II children, 45% acquired an improved DQ and 85% showed volume expansion of the contralateral hemisphere while 10% had an arrested developmental age (DA) and 5% showed no morphological development. In Class III/IV children, none acquired an improved DQ, 40% had an arrested DA, and 47% showed no morphological development. COMPARISON OF SURGICAL PROCEDURES. For disconnection of CC, interhemispheric approach (IH) and transventricular approach (TV) were compared. In 4 of 19 TV procedures, follow-up MRI revealed residual callosal fibers in the genu. IH enabled reliable disconnection of CC and was especially advantageous in anomalous and asymmetric CC frequently found in HM, while it necessitated another route for disconnection of PF. For disconnection of PF, periinsular approach (PI) and transopercular approach (TOP) were compared. PI necessitated a long corticectomy around the insula and a long disconnection down to the inferior horn behind the insular cortex, which resulted in a problematic blood loss in some cases of HM. TOP overcame the problem but resulted in a higher occurrence of impaired CSF circulation necessitating ventricular or subdural shunting (7 of 15 TOP vs. 1 of 11 PI). Reviewing these results we recently adopted Delalande[rsquo]s vertical hemispherotomy with our modification. Hemispherotomy for pediatric MCD achieved acceptable seizure control. Favorable seizure outcome was associated with improved psychomotor development and contralateral hemispheric development. Follow-up MRI is useful in confirming the completeness of disconnection and refining this complex surgical procedure.