Leff A P, Spitsyna G, Plant G T, Wise R J S
MRC Clinical Sciences Centre and Division of Neuroscience, Faculty of Medicine, Imperial College, Hammersmith Hospital, London, UK.
J Neurol Neurosurg Psychiatry. 2006 Sep;77(9):1004-7. doi: 10.1136/jnnp.2005.086983. Epub 2006 Jun 26.
The two most common types of acquired reading disorder resulting from damage to the territory of the dominant posterior cerebral artery are hemianopic and pure alexia. Patients with pronounced hemianopic alexia have a right homonymous hemianopia that encroaches into central or parafoveal vision; they read individual words well, but generate inefficient reading saccades when reading along a line of text. Patients with pure alexia also often have a hemianopia but are more disabled, making frequent errors on individual words; they have sustained damage to a brain region that supports efficient word identification.
To investigate the differences in lesion site between hemianopic alexia and pure alexia groups, as rehabilitative techniques differ between the two conditions.
High-resolution magnetic resonance images were obtained from seven patients with hemianopic alexia and from six patients with pure alexia caused by a left occipital stroke. The boundary of each lesion was defined and lesion volumes were then transformed into a standard stereotactic space so that regional comparisons could be made.
The two patient groups did not differ in terms of damage to the medial left occipital lobe, but those with pure alexia had additional lateral damage to the posterior fusiform gyrus and adjacent tissue.
Clinicians will be able to predict the type of reading disorder patients with left occipital lesions have from simple tests of reading speed and the distribution of damage to the left occipital lobe on brain imaging. This information will aid management decisions, including recommendations for reading rehabilitation.
由优势侧大脑后动脉供血区受损导致的两种最常见的后天性阅读障碍类型是偏盲性失读症和纯失读症。患有明显偏盲性失读症的患者有右侧同向偏盲，累及中心或旁中心视力；他们单个单词认读良好，但沿文本行阅读时会产生低效的阅读扫视。纯失读症患者通常也有偏盲，但功能障碍更严重，单个单词常出错；他们大脑中支持有效单词识别的区域受到持续性损伤。
研究偏盲性失读症组和纯失读症组之间病变部位的差异，因为这两种情况的康复技术不同。
对7例因左侧枕叶卒中导致偏盲性失读症的患者和6例因左侧枕叶卒中导致纯失读症的患者进行高分辨率磁共振成像检查。确定每个病变的边界，然后将病变体积转换到标准立体定向空间，以便进行区域比较。
两组患者在左侧枕叶内侧损伤方面无差异，但纯失读症患者在后梭状回及相邻组织有额外的外侧损伤。
临床医生能够通过简单的阅读速度测试以及脑成像上左侧枕叶损伤的分布情况，预测左侧枕叶病变患者的阅读障碍类型。这些信息将有助于制定管理决策，包括阅读康复建议。
