Summary Purpose To more definitively characterize Wada/fMRI language dominance discordance rates with the largest sample of epilepsy patients to date, and to examine demographic, clinical, and methodological predictors of discordance. Methods 229 epilepsy patients underwent both a standardized Wada test and a semantic-decision fMRI language protocol in a prospective research study. Language laterality indices were computed for each test using automated and double-blind methods, and Wada/fMRI discordance rates were calculated using objective criteria for discordance. Regression analyses were used to explore a range of variables that might predict discordance, including subject variables, Wada quality indices, and fMRI quality indices. Key findings Discordant results were observed in 14% of patients. Discordance was highest among those categorized by either test as having bilateral language. In a multivariate model, the only factor that predicted discordance was the degree of atypical language dominance on fMRI. Significance FMRI language lateralization is generally concordant with Wada testing. The degree of rightward shift of language dominance on fMRI testing is strongly correlated with Wada/fMRI discordance, suggesting that fMRI may be more sensitive than Wada to right hemisphere language processing, though the clinical significance of this increased sensitivity is unknown. The relative accuracy of fMRI vs. Wada testing for predicting post-surgical language outcome in discordant cases remains a topic for future research.

Among patients with epilepsy, atypical (rightward) language lateralization has been associated with left-handedness, a left seizure focus, an early age at seizure onset, and familial sinistrality, although these associations are not consistently observed. No study has examined all of these factors in relation to language lateralization in the same epilepsy sample, let alone in a sample comprised only of patients with temporal lobe epilepsy. Moreover, little consideration has been given in previous studies to how language lateralization might be influenced by the interplay between different factors, or how much unique variance in language lateralization is explained by each factor. The primary aim of this study was to examine the combined influences of handedness, side of seizure focus, age at seizure onset, and familial sinistrality on language lateralization in temporal lobe epilepsy patients. A secondary aim was to determine which factors uniquely contribute to the prediction of language lateralization. 162 patients with intractable temporal lobe epilepsy underwent functional MRI language mapping, from which language lateralization indexes were derived. Degree of handedness was measured via the Edinburgh Handedness Inventory. Main and 2-way interaction effects on language lateralization indexes were examined via linear regressions and Fisher exact tests. Significant effects were next examined in multiple regressions to identify unique predictors of language lateralization indexes. When examined in isolation in regressions, only left-handedness and a left seizure focus predicted atypical (rightward) language lateralization. These results, however, were qualified by interaction effects demonstrating that stronger left hand preference was associated with greater atypical language lateralization only among patients with a left seizure focus, an early or intermediate age at seizure onset, or no familial sinistrality. In follow-up multiple regressions, the interaction terms accounted for a significant amount of variance in language lateralization indexes above and beyond main effects. Additionally, side of seizure focus and its interaction with handedness uniquely predicted language lateralization indexes. Results indicate that degree of left-handedness is a marker of greater atypical (rightward) language lateralization in temporal lobe epilepsy but only in the context of seizure characteristics that have the potential to drive joint reorganization of language and hand preference (i.e., left seizure focus, or early or intermediate age at seizure onset) or in the absence of a genetic predisposition for left-handedness (i.e., no familial sinistrality). This study advances existing knowledge by illustrating how different factors combine to jointly affect language lateralization, and by identifying side of seizure focus and its interaction with handedness as unique predictors of language lateralization in temporal lobe epilepsy.

Objective Investigations of the validity of fMRI as an alternative to Wada language testing have yielded Wada/fMRI discordance rates of approximately 15%, but almost nothing is known regarding the relative accuracy of Wada and fMRI in discordant cases. The objective of this study was to determine whether the Wada test or language fMRI is more predictive of postoperative naming outcome following left anterior temporal lobectomy in discordant cases. Methods Among 229 epilepsy patients who prospectively underwent Wada and fMRI language testing, ten had discordant language lateralization results, underwent left anterior temporal lobectomy, and returned for postoperative language testing. The relative accuracy of Wada and fMRI for predicting language outcome was examined in these cases. Results FMRI provided the more accurate prediction of language outcome in seven patients, Wada was more accurate in two patients, and the two tests were equally accurate in one patient. Conclusions In cases of discordance, fMRI predicted post-surgical naming outcome with relatively better accuracy compared to the Wada test.

Concussion is a highly prevalent injury in contact and collision sports that has historically been poorly understood. An influx of sport-concussion research in recent years has led to a dramatic improvement in our understanding of the injury's defining characteristics and natural history of recovery. In this review, we discuss the current state of knowledge regarding the characteristic features of concussion and typical acute course of recovery, with an emphasis on the aspects of functioning most commonly assessed by clinicians and researchers (e.g., symptoms, cognitive deficits, postural stability). While prototypical clinical recovery is becoming better understood, questions remain regarding what factors (e.g., injury severity, demographic variables, history of prior concussions, psychological factors) may explain individual variability in recovery. Although research concerning individual differences in response to concussion is relatively new, and in many cases limited methodologically, we discuss the evidence about several potential moderators of concussion recovery and point out areas for future research. Finally, we describe how increased knowledge about the negative effects of and recovery following concussion has been translated into clinical guidelines for managing concussed athletes.

Traumatic brain injury (TBI) is a significant public health problem facing the United States and other industrialized countries around the world. National estimates of TBI in the United States range anywhere from 1.4 million to 4 million brain injuries per year, depending on the study and methods used to define and include cases (Coronado,