School of Population and Public Health, University of British Columbia, 217-2277 Wesbrook Mall, Vancouver, British Columbia V6T 2B5 Canada.
Stroke. 2011 Mar;42(3):728-33. doi: 10.1161/STROKEAHA.110.602938. Epub 2011 Jan 27.
A transient ischemic attack (TIA) is a brief ischemic episode characterized by rapid clinical resolution and not associated with permanent cerebral infarction. Whether changes in intracortical excitability persist and are related to clinical predictors of stroke risk after TIA remains unknown.
Participants were individuals with clinically resolved motor TIA with no structural lesions and healthy age-matched control participants. Single and paired-pulse transcranial magnetic stimulation was used to measure intracortical excitability. Recruitment curves for percent inhibition and facilitation were used to derive excitability thresholds. Correlations between threshold asymmetries and ABCD(2) score were performed.
Results showed a significant 3-way interaction with reduced inhibition and enhanced facilitation in the affected compared with unaffected hemisphere after TIA. No significant differences were present in healthy participants. Asymmetries in intracortical inhibition and facilitation were significantly correlated with ABCD(2) score.
The present study is the first, to our knowledge, to demonstrate altered intracortical inhibition and facilitation in the affected hemisphere after TIA. These changes occurred on average 2 weeks after clinical signs of TIA resolved and in the absence of structural lesions and were not present in healthy age-matched control participants. Furthermore, this study is the first, to our knowledge, to report that changes in intracortical excitability after TIA are associated with ABCD(2) score.
短暂性脑缺血发作（TIA）是一种短暂的缺血发作，其特征是临床迅速缓解，且不伴有永久性脑梗死。TIA 后皮质内兴奋性的变化是否持续存在，以及与中风风险的临床预测因素相关，目前尚不清楚。
参与者为临床缓解的运动性 TIA 患者，无结构病变，且为年龄匹配的健康对照者。采用单脉冲和双脉冲经颅磁刺激测量皮质内兴奋性。使用抑制和易化的百分率募集曲线来推导兴奋性阈值。对阈值不对称性与 ABCD(2)评分之间的相关性进行了分析。
结果显示，TIA 后，与未受影响的半球相比，受影响的半球的抑制减少和易化增强，存在显著的 3 重交互作用。健康参与者则没有明显差异。皮质内抑制和易化的不对称性与 ABCD(2)评分显著相关。
本研究首次证明，TIA 后受影响的半球存在皮质内抑制和易化的改变。这些变化平均发生在 TIA 临床症状缓解后 2 周，且无结构病变，在健康的年龄匹配对照组中则不存在。此外，本研究首次报告 TIA 后皮质内兴奋性的变化与 ABCD(2)评分相关。
