Sandler Evan B, Iddings Jennifer Ann, Minassian Karen, Field-Fote Edelle C
Crawford Research Institute, Shepherd Center, Atlanta, GA 30309, USA.
Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, 1090 Vienna, Austria.
Biomedicines. 2025 Sep 8;13(9):2195. doi: 10.3390/biomedicines13092195.
: Transcutaneous spinal stimulation (TSS) is a noninvasive stimulation approach to modulate spinal reflex circuit excitability after spinal cord injury (SCI) Posterior root muscle (PRM) reflexes can be used to characterize the change in excitability of spinal reflex circuits after TSS; these responses are likely influenced by stimulus parameters. : We compared PRM reflex responses to 3 TSS conditions: single-site continuous (SS-CONT), single-site burst (SS-BURST), and dual-site continuous (DS-CONT). Stimulation (frequency: 50 Hz, intensity: 80% soleus reflex threshold[RT]) was delivered for 30 min. The cathode was placed over the thoracic spine (T11-T12) and anodes placed paraumbilically; a second cathode over the lumbar spine (L1/2 or L2/3) was used for DS-CONT. PRM reflex responses in the soleus were elicited by paired 1 ms monophasic conditioning-test stimuli at a 50 ms interstimulus interval via the T11-12 cathode and paraumbilical anodes. Soleus PRM reflex indices included RT, response amplitude at 1.2xRT (RA), slope, area under the input-output curve (AUC). Paired-pulse indices were collected, including paired-pulse depression (PPD) and depression of the area under the curve (AUC). To assess the correlation between biomechanical and electrophysiologic measures of soleus spasticity, the ankle clonus drop test first drop excursion (FDE) was measured. All indices were measured at baseline and immediately post-intervention. : In whole-group analyses, PPD and AUC were significantly decreased. Significant decreases in PPD and AUC were identified only after the SS-CONT condition. No significant changes were identified in other PRM reflex indices after any of the 3 TSS conditions. No relationships between baseline FDE and any PRM reflex parameter were identified at baseline. : With stimulation intensity of 80% soleus RT, modulation of targeted spinal reflex circuits was observed only in the SS-CONT condition when the response of the conditioning and test stimuli were considered. In addition, stretch-induced spasticity of the soleus may not be consistent with electrophysiologic testing.
经皮脊髓刺激（TSS）是一种非侵入性刺激方法，用于调节脊髓损伤（SCI）后脊髓反射回路的兴奋性。后根肌肉（PRM）反射可用于表征TSS后脊髓反射回路兴奋性的变化；这些反应可能受刺激参数的影响。我们比较了PRM反射对三种TSS条件的反应：单部位连续（SS-CONT）、单部位爆发（SS-BURST）和双部位连续（DS-CONT）。以50Hz的频率、80%比目鱼肌反射阈值（RT）的强度进行刺激，持续30分钟。阴极置于胸椎（T11-T12）上方，阳极置于脐旁；DS-CONT时，在腰椎（L1/2或L2/3）上方使用第二个阴极。通过T11-12阴极和脐旁阳极，以50ms的刺激间隔施加配对的1ms单相条件刺激-测试刺激，引出比目鱼肌的PRM反射反应。比目鱼肌PRM反射指标包括RT、1.2xRT时的反应幅度（RA）、斜率、输入-输出曲线下面积（AUC）。收集配对脉冲指标，包括配对脉冲抑制（PPD）和曲线下面积抑制（AUC）。为了评估比目鱼肌痉挛的生物力学和电生理测量之间的相关性，测量了踝阵挛下降试验的首次下降幅度（FDE）。所有指标均在基线和干预后立即测量。在全组分析中，PPD和AUC显著降低。仅在SS-CONT条件后，PPD和AUC显著降低。在三种TSS条件中的任何一种之后，其他PRM反射指标均未发现显著变化。在基线时，未发现基线FDE与任何PRM反射参数之间的关系。当考虑条件刺激和测试刺激的反应时,在80%比目鱼肌RT的刺激强度下，仅在SS-CONT条件下观察到了对目标脊髓反射回路的调制。此外，拉伸诱导的比目鱼肌痉挛可能与电生理测试不一致。
