Assessing risk: Characterizing language performance in pediatric patients with intractable epilepsy pre- and post-surgical resection

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 X2 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 (X2 (2, 179) = 0.28, p = 0.88); however, inclusion of atypical organization, was related to surgery offered (X2 (3, 179) = 7.34, p = 0.06). We observed no significant difference between rates of curative or palliative-intent surgery in 3-category (X2 (2, 92) = 0.97, p = 0.62) or 4-category CLRI (X2 (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.

Determination of language dominance in pediatric patients with epilepsy for clinical decision-making: Correspondence of intracarotid amobarbitol procedure and fMRI modalities

Identification of the language dominant hemisphere is an essential part of the evaluation of potential pediatric epilepsy surgery patients. Historically, language dominance has been determined using the intracarotid amobarbitol procedure (IAP), but use of functional Magnetic Resonance Imaging (fMRI) scanning is becoming more common. Few studies examine the correspondence between fMRI and IAP in pediatric samples. The current study examined the agreement of hemispheric lateralization as determined by fMRI and IAP in a consecutive sample of 10 pediatric patients with epilepsy evaluated for epilepsy surgery. Data showed a strong correlation between IAP and fMRI lateralilty indices (r=.91) and 70% agreement in determination of hemispheric dominance, despite increased demonstration of bilateral or atypical language representation in this pediatric sample. Clinical implications and interpretation challenges are discussed.