A case series of PLS patients with frontotemporal dementia and overview of the literature

<i>Objective:</i> Primary lateral sclerosis (PLS) is a rare form of motor neuron disease characterised by UMN degeneration leading to slowly progressive spasticity. Whether it is a separate disease or a subtype of ALS has been debated. In ALS comorbid frontotemporal dementia (FTD) is frequently seen (±15%). However, cognitive and behavioural changes are generally not considered to be a part of PLS. <i>Methods:</i> To report the clinical findings and frequency of PLS patients that developed FTD in a referral-based cohort and provide an overview of the literature. <i>Results:</i> In our cohort six out of 181 (3.3%) PLS patients developed FTD. In the literature a few cases of PLS with FTD have been reported and only a limited number of small studies have investigated cognition in PLS. However, when these studies are summarised a pattern emerges with FTD diagnoses in ±2% and frontotemporal impairment in 22% of patients. <i>Conclusions:</i> These findings suggest that PLS is part of the FTD-MND continuum and would favour viewing it as a subtype of ALS. It is, however, not a restricted (isolated UMN involvement) phenotype.

研究目的：原发性侧索硬化症（Primary Lateral Sclerosis, PLS）是一类罕见的运动神经元病，以上运动神经元（Upper Motor Neuron, UMN）退行性变导致缓慢进展的痉挛为特征。关于其究竟为独立疾病，还是肌萎缩侧索硬化症（Amyotrophic Lateral Sclerosis, ALS）的亚型，学界一直存在争议。在ALS患者中，额颞叶痴呆（Frontotemporal Dementia, FTD）共病情况较为常见，发生率约为15%左右。不过，认知与行为改变通常不被认为是PLS的临床表现。
研究方法：本研究旨在报告一项转诊队列中并发FTD的PLS患者的临床特征与发病频率，并对相关文献进行综述。
研究结果：本队列共纳入181例PLS患者，其中6例（3.3%）并发FTD。现有文献中仅报道过少量PLS合并FTD的病例，且针对PLS患者认知功能的研究多为小样本规模，数量有限。但汇总现有研究后可发现，PLS患者中FTD确诊率约为2%，额颞叶功能损害发生率可达22%，呈现出明确的发病模式。
研究结论：本研究结果提示，PLS属于额颞叶痴呆-运动神经元病（Motor Neuron Disease, MND）连续谱系的一部分，支持将其归为ALS的亚型。但需注意，PLS并非局限于孤立性上运动神经元受累的表型。