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.
ABSTRACT
Objective To observe any change in the laterality index (LI) in the active volume of the hand motor cortex during rehabilitation after acute cerebral infarction and to analyze the mechanisms involved in the rehabilitation of motor function.Methods Sixteen patients with acute cerebral infarcts were administered standard but individualized rehabilitation training.Blood oxygenation-dependent functional magnetic resonance imaging (BOLD-fMRI) was used to evaluate the active volume of their hand sensorimotor cortex (SMC) and the LI,at admission and after 14 days of rehabilitation.The Fugl-Meyer motor assessment for the hand (FMA) was used to evaluate hand function.Ten healthy volunteers were recruited as a control group and subjected to a single BOLD-fMRI examination to confirm the location and the volume of the active area when performing the same rehabilitation exercises.Results The baseline LI of affected hand SMC activation was significantly smaller than that of the unaffected hand [(0.010 ±0.808) versus (0.789 ± 0.157)],but no significant difference was observed between the affected and the unaffected hands after treatment.Rehabilitation therapy significantly increased the SMC LI of affected hand activation when compared with the baseline,but no such effect was observed with the unaffected hand.In 12 patients with dysfunction of the right hand as evaluated by the FMA,the baseline LI of the affected hand was smaller than that of the unaffected hand and that of the healthy volunteers.Conclusion Rehabilitation after acute infarction can promote functional recovery.The LI of the affected hand reflects cerebral plasticity during rehabilitation after acute cerebral infarction.
ABSTRACT
OBJECTIVE: This study involves an experiment using functional magnetic resonance imaging (fMRI) to delineate neural network and laterality of language related brain activation for spoken and written Korean words in normal adults. METHOD: Eight normal right-handed Korean males, aged 20~33 years, were investigated. Language tasks consisted of auditory and visual verb generation tasks. In fMRI, twenty slices were obtained for each functional volume using single shot echoplanar image sequences. Data were motion corrected, coregistered, normalized, and statistically analyzed using SPM-96 software. The number of activated voxels were counted in each hemisphere to calculate the laterality index according to each language task. RESULTS: In auditory verb generation task, inferior frontal gyrus and superior temporal region were activated in the left side. Right temporal lobe was also activated in the superior and middle temporal areas. Other activated area included medial frontal lobe. Lateralization index of auditory verb generation task was +78.6 +/-30.7. In visual verb generation task, inferior frontal gyrus was activated in the left side. Medial frontal lobe, both lateral occipital lobe, and left parietal lobe were also activated. The laterality index was +87.6 +/- 10.1. CONCLUSION: We could delineate cortical regions subserved for spoken and written Korean language and laterality of language related brain activation using fMRI. These results can contribute to understand underlying mechanism of language disorders in brain injury patients and to investigate the pattern of reorganization of language network after rehabilitation.