Purpose: The current concept for hemispherotomy includes various lateral techniques and the vertical perithalamic hemispherotomy introduced by Delalande in 1992. We have chosen the vertical approach because of advantages that possibly influence outcome: the possibility to completely disconnect the hemisphere at the level of the thalamus obviating both the need to resect the insula and the need to open and dissect the subarachnoid space of the Sylvian fissure.
Methods: We retrospectively analyzed prospectively collected data of all patients who underwent vertical hemispherotomy at the Vienna pediatric epilepsy center. Seizure outcome was classified according to the International League Against Epilepsy (ILAE) proposal 2001.
Key findings: Follow-up data of 40 patients (22 male/18 female; median age 5.5 years; range 4.4 months to 20.1 years) were analyzed. Hemispherotomy was left in 26 and right in 14 patients. The underlying pathology was ischemic vascular in 19, malformation of cortical development (MCD) in 11, and other pathology in 10. No serious intraoperative complications were encountered. Only two infants (5.0%) needed blood replacement. There was one death on the fourth day after surgery caused by intractable hyponatremic brain edema. Three patients developed cerebrospinal fluid (CSF) disturbances, but only one needed a permanent ventriculoperitoneal (VP) shunt (2.5%). For outcome analysis we included 37 of 40 children with at least 12 months of follow-up. Thirty-four (91.9%) of 37 children were seizure-free (class 1a) after a median follow-up time of 3.7 years (range 12 month to 14.8 years).
Significance: We confirm the efficacy and safety of vertical parasagittal hemispherotomy as described by Delalande in a consecutive series of patients treated at our center since 1998. In addition, complete disconnection of the hemisphere in patients with MCD and/or patients with significant involvement of the insula was possible without the complications usually reported with other techniques.
Keywords: Epilepsy surgery; Hemispherotomy; Pediatric epilepsy; Vertical hemispherotomy.
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