Baxendale Sallie A, Thompson Pamela J
Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK.
University College Hospital, London, UK.
Epilepsia. 2021 Jul;62(7):1584-1593. doi: 10.1111/epi.16919. Epub 2021 May 10.
Although group studies provide some support for the material-specific model of memory function, there are considerable individual variations in memory function in people with temporal lobe epilepsy, even in those with the same underlying pathology. In this proof-of-concept study, we examined the sensitivity and specificity of a single measure of an individual's relative strength for the encoding of verbal or visual learning.
Six hundred ninety-two patients with left hemisphere language dominance and unilateral hippocampal sclerosis completed verbal and visual encoding tasks with similar test structures as part of their presurgical evaluation. Three hundred one patients had right hippocampal sclerosis (RHS), and 391 patients had left hippocampal sclerosis (LHS). A memory specialization index (MSI) was calculated by subtracting the Visual Learning z-score from the Verbal Learning z-score. A positive value on the MSI indicates a relative strength in verbal learning. A negative score indicates a relative strength in visual learning.
Employing cut-offs of ±1, the MSI had a positive predictive value of 71% (confidence interval [CI] 95% 0.64-0.77) for LHS and 64% (CI 95% 0.55-0.74) for RHS and was superior to the standalone z-scores from the verbal and visual tests in each respect. In the LHS group, the MSI was significantly correlated with age and duration of epilepsy. Older patients who had a longer duration of epilepsy were more likely to demonstrate a similar level of impairment in both verbal and visual learning, with a decreasing discrepancy between the scores on the two tasks over time.
Our MSI provides a measure with high specificity for RHS. The pattern of strengths and weaknesses in visual and verbal encoding may evolve with age and duration of epilepsy, and clinicians should be aware of these factors when interpreting the lateralizing significance of test scores, particularly in a presurgical setting.
尽管群体研究为记忆功能的材料特异性模型提供了一些支持，但颞叶癫痫患者的记忆功能存在相当大的个体差异，即使是那些具有相同潜在病理的患者。在这项概念验证研究中，我们检验了一种单一测量方法对个体在言语或视觉学习编码方面相对优势的敏感性和特异性。
692例左半球语言优势且单侧海马硬化的患者完成了言语和视觉编码任务，这些任务具有相似的测试结构，作为其术前评估的一部分。301例患者为右侧海马硬化（RHS），391例患者为左侧海马硬化（LHS）。通过从言语学习z分数中减去视觉学习z分数来计算记忆专业化指数（MSI）。MSI上的正值表示言语学习方面的相对优势。负分数表示视觉学习方面的相对优势。
采用±1的临界值，MSI对LHS的阳性预测值为71%（95%置信区间[CI] 0.64 - 0.77），对RHS为64%（CI 95% 0.55 - 0.74），并且在各方面均优于言语和视觉测试的单独z分数。在LHS组中，MSI与年龄和癫痫病程显著相关。癫痫病程较长的老年患者在言语和视觉学习方面更有可能表现出相似程度的损伤，随着时间推移，两项任务得分之间的差异逐渐减小。
我们的MSI对RHS具有高特异性的测量方法。视觉和言语编码中的优势和劣势模式可能会随着年龄和癫痫病程而演变，临床医生在解释测试分数的定位意义时应意识到这些因素，特别是在术前环境中。
