Abstracts

Rationale: Cognitive decline, including language and intellectual impairments, is frequently associated with childhood epilepsy. Thus, the objective of medical and surgical treatments should be not only to control seizures but also to reduce neurodevelopmental comorbidities. Resective or disconnective surgery (RDS) is utilized for refractory seizures, leading to relatively good seizure outcomes if the responsible epileptogenic focus can be identified. RDS may also have a significant influence on cognitive outcomes, which is an additional issue with childhood epilepsy, although the effects have not been well characterized. Specifically, with respect to multilobar surgeries, a concern exists that more brain functions may be lost following this more extensive surgery. The posterior cortex, including the parietal, occipital, and temporal lobes, is most often the target of multilobar surgeries, with the exception of hemispherotomy; however, postoperative cognitive outcomes have not been investigated in detail. Methods: In this study, we retrospectively reviewed the results for 20 children who underwent multilobar RDS of the posterior cortex and were followed for greater than 12 months after surgery. Preoperative seizures occurred as spasms in 12 patients, tonic seizures in three patients, simple or complex partial seizures in eight patients, and secondary generalized seizures in one patient. All patients with spasms had been diagnosed with infantile spasms resistant to adrenocorticotrophic hormone treatment. MRI identified cortical malformations in ten patients, a focal vascular insult in one patient, and an absence of focal lesions in nine patients. Among the patients with lesions identified by MRI, RDS was an initial option for 11 patients, based on clear EEG focality. In the remaining 9 patients, stepwise procedures of callosotomy and RDS were applied (with an interval of 4-30 months between procedures), due to reduced lateralized features of the seizures and EEG. Age at initial surgery ranged from 8 to 88 months, and follow-up ranged from 12 to 71 months. Results: Nine patients, including five with spasms and four with other seizures, remained seizure-free throughout the entire follow-up period. Developmental outcomes were assessed, using developmental quotient (DQ) scores, in 18 patients, including motor, language, and social subscales. Receptive language DQ significantly improved in seven patients, remained unchanged in nine, and declined in 2 patients. Expressive language significantly improved in seven patients, remained unchanged in six, and declined in five patients. No patients experienced significant improvement in physical motor or manipulation DQ, while ten and eleven patients, respectively, maintained pre-surgery levels of these DQ scores. Postoperative DQ gain was significantly higher in receptive language and social relationship DQ than in physical motor and manipulation DQ. These outcomes were independent of age at surgery, duration of illness, type of seizures, surgical procedures, and postoperative seizure outcomes. Conclusions: Higher cognitive and receptive language functions, as well as primary sensory centers, exist in the posterior cortex. Despite this, extensive RDS of the posterior cortex had a more positive influence on receptive language than did motor development. This may occur because such language functions were formed in, or translocated to, the contralateral, healthier hemisphere during the course of the development of epilepsy. Our data also suggest that extensive surgery is beneficial for language development, although physical motor and manipulation functions are occasionally delayed, probably due to the loss of primary visual and sensory centers. Funding: None.