Ichikawa Hiroo, Kawamura Mitsuru
Department of Neurology, Showa University School of Medicine, 1-5-8, Hatanodai, Shinagawa-ku, Tokyo 142-8666, Japan.
Brain Nerve. 2010 Apr;62(4):435-40.
For a long time, amyotrophic lateral sclerosis (ALS) was thought to be a neuro-degenerative disease with selective involvement of the motor neuron system. However, it has recently been established that ALS is a multisystem disorder that not only involve the motor system but also affects cognition. A typical cognitive impairment in ALS is frontotemporal dementia: a clinical subtype of frontotemporal lobar degeneration (FTLD). Furthermore, language impairment, including progressive non-fluent aphasia (PA) and semantic dementia (SD), which are also FTLD subtypes, have been linked to bulbar-onset ALS. Beside recent studies a Japanese paper published in 1893 gives an account of aphasia in bulbar-onset ALS. Interestingly, this was the first account of aphasia in Japan. Thus, language-related problems in ALS may have been overlooked, because evaluation of aphasic problems in ALS patients is difficult, mainly because of progressive bulbar or pseudo-bulbar palsy that results in and dysarthria. From a clinical point of view, progressing bulbar symptoms and medical interventions, such artificial ventilation make it difficult to evaluate language functions in ALS. However, we do observe frequent omission and paragraphia of kana letters, and syntactic errors in writing. Interestingly, some patients make exhibit errors exclusively in the case of kanji characters. Thus, evaluation of writing samples is important if order to identify language problems in ALS patients. The findings may also provide additional information such as dissociation between errors made in kana and kanji characters. The characteristic features of writing errors are thought to reflect the nature of aphasia including PA and SD, that are easily masked by dysarthria. In addition, writing errors can appear as "isolated agraphia" without aphasia and dementia. Pathologically, writing errors should indicate the brain regions involved by ALS, e.g., hemispheric dominance and frontal or temporal lobe involvement. In addition, selective involvement of Exner's writing center in the frontal lobe may be responsible for "isolated agraphia". Hence, further studies are required to determine the clinical significance of writing errors in ALS patients and their pathological correlation.
长期以来，肌萎缩侧索硬化症（ALS）一直被认为是一种选择性累及运动神经元系统的神经退行性疾病。然而，最近已经确定，ALS是一种多系统疾病，不仅累及运动系统，还会影响认知。ALS中一种典型的认知障碍是额颞叶痴呆：额颞叶变性（FTLD）的一种临床亚型。此外，语言障碍，包括进行性非流利性失语（PA）和语义性痴呆（SD），它们也是FTLD的亚型，已被发现与延髓起病的ALS有关。除了近期的研究外，一篇1893年发表的日本论文描述了延髓起病的ALS中的失语症。有趣的是，这是日本对失语症的首次描述。因此，ALS中与语言相关的问题可能一直被忽视，因为评估ALS患者的失语问题很困难，主要是由于进行性延髓或假性延髓麻痹导致构音障碍。从临床角度来看，进行性延髓症状和医疗干预，如人工通气，使得评估ALS患者的语言功能变得困难。然而，我们确实观察到假名字母的频繁遗漏和错写，以及书写中的句法错误。有趣的是，一些患者仅在汉字书写时出现错误。因此，为了识别ALS患者的语言问题，评估书写样本很重要。这些发现还可能提供额外的信息，如假名和汉字书写错误之间的分离。书写错误的特征被认为反映了包括PA和SD在内的失语症的本质，而这些很容易被构音障碍所掩盖。此外，书写错误可能表现为无失语症和痴呆的“孤立性失写症”。在病理上，书写错误应该表明ALS所累及的脑区，例如半球优势以及额叶或颞叶的受累情况。此外，额叶中埃克斯纳书写中枢的选择性受累可能是“孤立性失写症”的原因。因此，需要进一步研究来确定ALS患者书写错误的临床意义及其病理相关性。
