Department of Neurology, Seoul National University Hospital, Seoul, Republic of Korea.
Department of Translational Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.
PLoS One. 2023 Oct 13;18(10):e0292460. doi: 10.1371/journal.pone.0292460. eCollection 2023.
The available quantitative methods for evaluating bulbar dysfunction in patients with amyotrophic lateral sclerosis (ALS) are limited. We aimed to characterize vowel properties in Korean ALS patients, investigate associations between vowel parameters and clinical features of ALS, and analyze subclinical articulatory changes of vowel parameters in those with perceptually normal voices. Forty-three patients with ALS (27 with dysarthria and 16 without dysarthria) and 20 healthy controls were prospectively collected in the study. Dysarthria was assessed using the ALS Functional Rating Scale-Revised (ALSFRS-R) speech subscores, with any loss of 4 points indicating the presence of dysarthria. The structured speech samples were recorded and analyzed using Praat software. For three corner vowels (/a/, /i/, and /u/), data on the vowel duration, fundamental frequency, frequencies of the first two formants (F1 and F2), harmonics-to-noise ratio, vowel space area (VSA), and vowel articulation index (VAI) were extracted from the speech samples. Corner vowel durations were significantly longer in ALS patients with dysarthria than in healthy controls. The F1 frequency of /a/, F2 frequencies of /i/ and /u/, the VSA, and the VAI showed significant differences between ALS patients with dysarthria and healthy controls. The area under the curve (AUC) was 0.912. The F1 frequency of /a/ and the VSA were the major determinants for differentiating ALS patients who had not yet developed apparent dysarthria from healthy controls (AUC 0.887). In linear regression analyses, as the ALSFRS-R speech subscore decreased, both the VSA and VAI were reduced. In contrast, vowel durations were found to be rather prolonged. The analyses of vowel parameters provided a useful metric correlated with disease severity for detecting subclinical bulbar dysfunction in ALS patients.
目前用于评估肌萎缩侧索硬化症（ALS）患者球部功能障碍的定量方法有限。本研究旨在描述韩国 ALS 患者的元音特征，探讨元音参数与 ALS 临床特征的相关性，并分析那些语音感知正常的患者的元音参数的亚临床发音变化。本研究前瞻性收集了 43 例 ALS 患者（27 例构音障碍，16 例无构音障碍）和 20 名健康对照者。构音障碍使用肌萎缩侧索硬化功能评定量表修订版（ALSFRS-R）的言语亚量表进行评估，任何 4 分的丧失都表明存在构音障碍。使用 Praat 软件对结构化语音样本进行记录和分析。对于三个角元音（/a/、/i/和/u/），从语音样本中提取元音时长、基频、前两个共振峰频率（F1 和 F2）、谐波噪声比、元音空间面积（VSA）和元音发音指数（VAI）的数据。有构音障碍的 ALS 患者的角元音时长明显长于健康对照组。/a/的 F1 频率、/i/和/u/的 F2 频率、VSA 和 VAI 在有构音障碍的 ALS 患者和健康对照组之间存在显著差异。曲线下面积（AUC）为 0.912。/a/的 F1 频率和 VSA 是区分尚未出现明显构音障碍的 ALS 患者和健康对照组的主要决定因素（AUC 0.887）。在线性回归分析中，随着 ALSFRS-R 言语亚量表评分的降低，VSA 和 VAI 均降低。相比之下，元音时长则延长。元音参数分析为检测 ALS 患者亚临床球部功能障碍提供了一种与疾病严重程度相关的有用指标。
