Department of Neurology, Faculty of Medicine and University Hospital of Cologne, Cologne, Germany.
Center for Rare Diseases, Faculty of Medicine and University Hospital of Cologne, Cologne, Germany.
Muscle Nerve. 2024 Nov;70(5):954-962. doi: 10.1002/mus.28229. Epub 2024 Aug 13.
INTRODUCTION/AIMS: Myotonia is a key symptom of myotonic dystrophies (DM), and its quantification is challenging. This exploratory study evaluated the utility of tissue Doppler ultrasound (TDU) to assess myotonia in DM.
Twelve DM patients (seven type-1 DM [DM1] and five type-2 DM [DM2]) and 20 age-matched healthy subjects were included in this cross-sectional study. After measuring cross-sectional areas of the flexor digitorum superficialis (FDS) and extensor digitorum communis (EDC) muscles in a resting state, muscle contraction/relaxation time, time to peak tissue velocity, peak tissue velocity and velocity gradients of these muscles were measured via TDU while performing forced fist unclenching after fist closure. Additionally, grip strength, Medical Research Council Sum score and patient-reported myotonia severity scores were assessed.
DM1 and DM2 patients had a lower grip strength than healthy subjects (p = .0001/p = .002). Patient-reported myotonia did not differ between DM1 and DM2 patients. DM1 patients revealed FDS and EDC atrophy compared to DM2 patients and healthy subjects (p = .003/p = .004). TDU revealed prolonged muscle contraction and relaxation times in both DM subtypes, with prolonged time to reach FDS peak relaxation velocity and altered peak FDS relaxation velocity only in DM1 patients (p = .03/p = .003). Peak FDS relaxation velocity correlated inversely with C(C)TG repeat numbers in DM patients. Sensitivity of TDU parameters to detect myotonic dystrophy varied between 50% and 75%, with a specificity of 95%.
Our exploratory study suggests that TDU could serve as a novel tool to quantify myotonia in DM patients, but larger follow-up studies are warranted to validate its diagnostic accuracy.
简介/目的：肌强直是肌强直性营养不良症（DM）的一个关键症状，其量化具有挑战性。本探索性研究评估了组织多普勒超声（TDU）评估 DM 中肌强直的效用。
本横断面研究纳入了 12 名 DM 患者（7 名 1 型 DM [DM1]和 5 名 2 型 DM [DM2]）和 20 名年龄匹配的健康对照者。在休息状态下测量了屈指浅肌（FDS）和指总伸肌（EDC）的横截面积后，通过 TDU 在握拳后用力握拳时测量这些肌肉的收缩/松弛时间、达到峰值组织速度的时间、峰值组织速度和速度梯度。此外，还评估了握力、医学研究理事会总和评分和患者报告的肌强直严重程度评分。
DM1 和 DM2 患者的握力低于健康对照组（p=.0001/p=.002）。DM1 和 DM2 患者的患者报告的肌强直无差异。DM1 患者的 FDS 和 EDC 萎缩与 DM2 患者和健康对照组相比（p=.003/p=.004）。两种 DM 亚型的 TDU 均显示肌肉收缩和松弛时间延长，仅 DM1 患者的 FDS 达到峰值松弛速度的时间延长和 FDS 峰值松弛速度改变（p=.03/p=.003）。FDS 峰值松弛速度与 DM 患者的 C（C）TG 重复数呈负相关。TDU 参数检测肌强直的敏感性在 50%至 75%之间，特异性为 95%。
我们的探索性研究表明，TDU 可作为量化 DM 患者肌强直的一种新工具，但需要更大的随访研究来验证其诊断准确性。
