Manafi-Khanian B, Arendt-Nielsen L, Frøkjaer J B, Graven-Nielsen T
Laboratory for Musculoskeletal Pain and Motor Control, Department of Health Science and Technology, Center for Sensory-Motor Interaction (SMI), Faculty of Medicine, Aalborg University, Denmark.
Department of Clinical Medicine, Aalborg University, Denmark.
Eur J Pain. 2015 Nov;19(10):1456-66. doi: 10.1002/ejp.677. Epub 2015 Feb 23.
Cuff algometry is used for quantitative pain assessment although it is not clarified which tissues are actually challenged by the stimulation. This study investigated the mechanical stress and strain distribution in superficial and deep tissues during cuff algometry applied on the lower leg at three different intensities (mild pressure, pain threshold and supra pain threshold).
A computational three-dimensional finite element model of the lower leg with three different layers of soft tissue was developed based on magnetic resonance imaging (MRI) recorded during cuff stimulation. Tissue indentation maps were extracted from the MRI scans and transferred into the model as displacement of boundary condition. In all stimulation conditions, the mean stress of subcutaneous adipose and muscle tissue below the cuff decreased compared with the skin while the mean strain peaked in subcutaneous adipose and decreased in other tissues.
At pain threshold stimulation intensity, the mean muscle stress was 2.9% of mean skin stress and the mean muscle strain was 55.1% of mean strain in adipose layer. The mean stress and strain increased by 30.4% and 27.1%, respectively, in muscle tissue from painful to supra pain threshold stimulation. The stress and strain was mainly focused around the bones and superficially under cuff.
This study shows the better capability of cuff algometry for stimulation of deep somatic tissue in terms of generation of mechanical stress and strain in contrast to the more superficial muscle tissue previously demonstrated to be strained by single-point pressure algometry.
袖带测痛法用于定量疼痛评估，尽管尚未明确刺激实际作用于哪些组织。本研究调查了在小腿上以三种不同强度（轻度压力、疼痛阈值和超疼痛阈值）应用袖带测痛法时，浅表和深部组织中的机械应力和应变分布。
基于袖带刺激期间记录的磁共振成像（MRI），建立了具有三层不同软组织的小腿三维计算有限元模型。从MRI扫描中提取组织压痕图，并作为边界条件的位移输入模型。在所有刺激条件下，与皮肤相比，袖带下方皮下脂肪和肌肉组织的平均应力降低，而平均应变在皮下脂肪中达到峰值，在其他组织中降低。
在疼痛阈值刺激强度下，平均肌肉应力为平均皮肤应力的2.9%，平均肌肉应变是脂肪层平均应变的55.1%。从疼痛刺激到超疼痛阈值刺激，肌肉组织中的平均应力和应变分别增加了30.4%和27.1%。应力和应变主要集中在骨骼周围和袖带下方的浅表部位。
本研究表明，与先前证明受单点压力测痛法影响的较浅表肌肉组织相比，袖带测痛法在产生机械应力和应变方面对深部躯体组织的刺激能力更强。
