Neurophysiological predictors of aphasia recovery in patients with large left-hemispheric infarction

Abstract

Background:Although the rehabilitation of aphasia has been extensively studied, the prediction of language outcome still has not received sufficient attention. The aim of this study was to predict the language outcome using mismatch negativity (MMN) in patients with large left-hemispheric infarction.Methods:MMN was elicited by an oddball paradigm in which a standard tone (1000 Hz) and deviant tone (1500 Hz) were presented at 90% and 10% of the number of tones, respectively. The mean amplitudes and laterality indexes (LIs) of MMN were measured over the prefrontal, frontal, central, parietal, temporal, and perisylvian electrodes and both hemispheres during the first 7 days (session 1) and 10 to 20 days (session 2) post-onset. Mixed three-way analysis of variance (ANOVA) was used to investigate differences in these factors between two aphasia groups (the good recovery group and poor recovery group). The predictive value of the most significant LI was also compared with the score of National Institutes of Health Stroke Scale score and low-density volume on computed tomography.Results:A total of 18 patients were enrolled in this study. Mixed three-way ANOVA showed no interaction effect of session × region of interest (ROI) × group (F [3.59, 57.38] = 1.301, P = 0.282) and no interaction effect of ROI × group (F [1.81, 29.01] = 0.71, P = 0.487) and session × group (F [1.00, 16.00] = 0.084, P = 0.776) for MMN amplitude. No interaction effect of session × ROI × group (F [1.79, 28.58] = 0.62, P = 0.530), but an interaction effect of session × group (F [1.00, 16.00] = 5.21, P = 0.036) was found for LIs. In the poor recovery group, the LIs of MMN over all the ROIs, except the parietal area, became more negative at session 2 than those at session 1 (P < 0.05), but this effect was not observed in the good recovery group. Additionally, significant differences were observed in the LIs at session 2 between the two groups (P < 0.05). The LI over the perisylvian area at session 2 had the highest predictive value with an area under the curve of 0.963 (95% confidence interval: 0.884–1.000). An LI score >−0.36 over the perisylvian area suggested good recovery, but a score <−0.36 suggested poor recovery. The LI cut-off value of −0.36 had the highest sensitivity (90.0%) and specificity (87.5%) for predicting a good language outcome at 3 months post-stroke.Conclusion:LIs of MMN amplitudes at approximately 2 weeks post left-hemisphere stroke serve as more sensitive predictors of language outcome, among which the LI over the perisylvian area exhibits the best predictive value.

Prolonged intermittent theta burst stimulation for post-stroke aphasia: protocol of a randomized, double-blinded, sham-controlled trial

“…In PSA patients, monitoring power in the theta, alpha, and beta frequency bands via EEG can serve as both a repeated and a sensitive measure to assess function and detect changes in patients with chronic aphasia ( 62 ). Both N400 and MMN are components closely related to language processing, and the abnormalities in two components suggest difficulties in processing and understanding semantic information as well as reduced sensitivity and adaptability to rule violations in language ( 50 , 63 ). Reduction of the N400 is associated with language improvement ( 31 ).…”

“…Reduction of the N400 is associated with language improvement ( 31 ). In another longitudinal study utilizing the MMN paradigm, it’s found that the laterality index of MMN amplitudes at approximately 2 weeks post left-hemisphere stroke serve as more sensitive predictors of language outcome, among which the laterality index over the perisylvian area exhibits the best predictive value ( 50 ). However, there is a limited amount of research investigating the changes in MMN and N400 in response to TMS before and after treatment.…”

“…Each tone is presented for 50 ms. In total, 500 stimulations are delivered in each experimental block, comprising approximately 5 min and 45 s. The frequent 1,000 Hz tones is served as standard stimulation, while the infrequent 1,500 Hz tones are deviant stimulation in this auditory oddball paradigm ( 50 ).…”