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.此前已有研究提出采用肌肉束颤超声检测，以评估肌萎缩侧索硬化（ALS）患者的下运动神经元（lower motor neuron, LMN）功能障碍。鉴于肌萎缩侧索硬化与额颞叶变性（frontotemporal degeneration, FTD）存在疾病谱连续性，本研究旨在评估肌肉超声（muscle ultrasound, MUS）在额颞叶变性患者中的应用可行性，以及束颤的检出率。 本研究纳入22例额颞叶变性患者，采用7MHz线阵探头对双侧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例与患者匹配的认知完好对照受试者，以及6例肌萎缩侧索硬化患者作为对照队列。 研究结果显示，肌肉超声在所有受试者中均具备可行性、可靠性，且耐受性良好。2例合并运动神经元病（Motor Neuron Disease, MND）的额颞叶变性患者束颤评分极高，与肌萎缩侧索硬化患者的评分水平相近；其余20例额颞叶变性患者的平均束颤评分显著高于对照组，其中6例患者（占比30%）的束颤评分超出对照人群的正常范围。疾病进展速率与束颤评分呈显著相关。 综上，肌肉超声可便捷应用于额颞叶变性患者，是一种无创性检查技术，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额颞叶变性患者中较为常见，或可用于识别临床病程存在差异的患者亚群。