Muscle ultrasonography for detecting fasciculations in frontotemporal dementia

Ultrasound detection of muscle fasciculations was recently proposed for assessing lower motor neuron (LMN) dysfunction in ALS patients. Given the continuum between ALS and frontotemporal degeneration (FTD), the aim of the present study was to evaluate muscle ultrasound (MUS) in FTD both for feasibility and prevalence of fasciculations. Twenty-two FTD patients were examined (five muscles bilaterally: biceps brachii, first dorsalis interosseous, T10 paraspinalis, vastus lateralis, tibialis anterior) with a 7-MHz linear array transducer and a fasciculation score (FS) computed. Twenty-two matched cognitively-intact control subjects and six ALS patients were also included. Results showed that MUS was feasible, reliable and well tolerated in all subjects. Two FTD/MND patients displayed very high FS values, similar to those in ALS patients. The remaining 20 FTD patients displayed a mean FS value significantly higher than the control group with six patients (30%) having FS values out of the range of controls. Disease progression rate correlated with the FS. In conclusion, MUS can be easily applied to FTD patients and represents a non-invasive technique for defining LMN involvement in these patients. LMN dysfunction is a frequent condition in FTD and might identify a subset of patients with a different clinical course.

近年来，肌束颤（muscle fasciculations）超声检测技术被提出，用于评估肌萎缩侧索硬化（Amyotrophic Lateral Sclerosis, ALS）患者的下运动神经元（Lower Motor Neuron, LMN）功能障碍。鉴于ALS与额颞叶变性（Frontotemporal Degeneration, FTD）之间存在疾病谱连续性，本研究旨在评估肌超声（Muscle Ultrasound, MUS）在FTD患者中的应用可行性，以及肌束颤的患病率。
本研究纳入22例FTD患者，采用7 MHz线阵探头对其双侧5块肌肉（肱二头肌、第一骨间背侧肌、T10棘旁肌、股外侧肌、胫骨前肌）进行超声检查，并计算束颤评分（Fasciculation Score, FS）。同时纳入22例匹配的认知完好对照受试者，以及6例ALS患者作为对照队列。
研究结果显示，肌超声检查在所有受试者中均具备可行性、可靠性，且耐受性良好。其中2例FTD合并运动神经元病（Motor Neuron Disease, MND）患者的FS值极高，与ALS患者的FS值水平相近。剩余20例FTD患者的平均FS值显著高于健康对照组，其中6例患者（占比30%）的FS值超出了健康对照的正常范围。患者的疾病进展速率与FS值存在显著相关性。
综上，肌超声检查可便捷应用于FTD患者，是一种无创性技术，可用于明确此类患者的下运动神经元受累情况。下运动神经元功能障碍在FTD患者中较为常见，或可用于甄别出具有不同临床病程的FTD亚组患者。