fMRI prediction of naming change after adult temporal lobe epilepsy surgery: Activation matters

Abstract

Summary Objective We aimed to predict language deficits after epilepsy surgery. In addition to evaluating surgical factors examined previously, we determined the impact of the extent of functional magnetic resonance imaging (fMRI) activation that was resected on naming ability. Method Thirty‐five adults (mean age 37.5 ± 10.9 years, 13 male) with temporal lobe epilepsy completed a preoperative fMRI auditory description decision task, which reliably activates frontal and temporal language networks. Patients underwent temporal lobe resections (20 left resection). The Boston Naming Test (BNT) was used to determine language functioning before and after surgery. Language dominance was determined for Broca and Wernicke area (WA) by calculating a laterality index following statistical parametric mapping processing. We used an innovative method to generate anatomic resection masks automatically from pre‐ and postoperative MRI tissue map comparison. This mask provided the following: (a) resection volume; (b) overlap between resection and preoperative activation; and (c) overlap between resection and WA. We examined postoperative language change predictors using stepwise linear regression. Predictors included parameters described above as well as age at seizure onset (ASO), preoperative BNT score, and resection side and its relationship to language dominance. Results Seven of 35 adults had significant naming decline (6 dominant‐side resections). The final regression model predicted 38% of the naming score change variance (adjusted r2 = 0.28, P = 0.012). The percentage of top 10% fMRI activation resected (P = 0.017) was the most significant contributor. Other factors in the model included WA LI, ASO, volume of WA resected, and WA LI absolute value (extent of laterality). Significance Resection of fMRI activation during a word‐definition decision task is an important factor for postoperative change in naming ability, along with other previously reported predictors. Currently, many centers establish language dominance using fMRI. Our results suggest that the amount of the top 10% of language fMRI activation in the intended resection area provides additional predictive power and should be considered when planning surgical resection.

Naming fMRI predicts the effect of temporal lobe resection on language decline

“…Only a few studies have investigated the potential of fMRI to predict naming decline in individual patients . In LTLE, an auditory naming temporal lobe LI of >0.18 predicted a clinically relevant naming decline with a PPV of 54% with 100% sensitivity and 58% specificity.…”

Patterns and predictors of language representation and the influence of epilepsy surgery on language reorganization in children and young adults with focal lesional epilepsy

“…Rather unexpectedly, we found only a weak correlation between the side of lesion and of its surgical removal and postoperative LI changes. This finding might be due to the high percentage of small lesionectomies and anterior temporal lobectomies [62] and the low percentage of non-dominant resections in our sample [63].…”

Language Dominance in Patients With Malformations of Cortical Development and Epilepsy

“…These patients underwent early postsurgical reorganization of the language function to the contralateral hemisphere as a compensatory mechanism for regaining language abilities (28). The extent of the resection of the top 10% of the presurgically activated voxels predicted naming decline after temporal lobectomy (32), as it was demonstrated in a study on 35 adult patients with TLE who underwent epilepsy surgery. Right-hemispheric or bilateral dominance were associated with the greater postsurgical language decline (32).…”

“…Several techniques such as Wada test, fMRI, positron emission tomography, or magnetoencephalography have been used for examining language dominance. In epilepsy patients, there is a much greater variability of language dominance compared to healthy subjects, and it ranges from exclusively left-hemispheric dominance to bilateral symmetric and strong right-hemispheric dominance (26–32). About 30% of patients with localization-related epilepsies exhibit atypical language dominance (30).…”