Association of the cognitive lateralization rating Index with surgical variables of a national cohort of pediatric patients with epilepsy.

Objective: Surgery is a standard treatment for medically refractory epilepsy, and many factors contribute to determining surgical approaches. The Cognitive Lateralization Rating Index (CLRI) quantifies the degree of dysfunction evident and can suggest atypical neuroanatomical functional organization if dominant skills remain despite left-hemisphere seizure foci (i.e., 'atypically-organized'). We sought to elucidate associations between surgical rate, intent, and procedure type based on CLRI categories.

Methods: Frequencies and descriptive statistics were run in addition to X test of independence and ANOVA evaluating CLRI versus surgical variables. 3-category CLRI included: dominant, non-dominant hemisphere, and non-lateralized dysfunction. 4-catgeory CLRI included the additional 'atypically organized' category.

Results: Of 179 patients with CLRI scores, 139 were offered surgery (78%). Left-hemisphere seizure foci were observed in 51% of patients. There was no relationship between surgery offered and 3-category CLRI (X (2, 179) = 0.28, p = 0.88); however, inclusion of atypical organization, was related to surgery offered (X (3, 179) = 7.34, p = 0.06). We observed no significant difference between rates of curative or palliative-intent surgery in 3-category (X (2, 92) = 0.97, p = 0.62) or 4-category CLRI (X (3, 92) = 2.36, p = 0.50). Results trended towards curative procedures (58.7%) with no significant difference between rates of procedures amongst CLRI groups. There was no statistically significant difference between pre- and postoperative cognitive results.

Conclusion: Not considering atypical organization may lead to overestimating surgical risk in patients with left-hemisphere seizure foci. While significant differences between surgical offerance, intent, or procedure were not observed, results trended towards significance once consideration of atypical organization was included. Further investigation of these variables in addition to surgical and cognitive outcomes is warranted.