Li Sheng, Bhadane Minal, Gao Fan, Zhou Ping
Department of Physical Medicine and Rehabilitation, McGoven Medical School, University of Texas Health Science Center at Houston, Houston, TX, United States.
TIRR Memorial Hermann Research Center, TIRR Memorial Hermann Hospital, Houston, TX, United States.
Front Neurol. 2017 Nov 27;8:627. doi: 10.3389/fneur.2017.00627. eCollection 2017.
Startling acoustic stimulation (SAS), via activation of reticulospinal (RS) pathways, has shown to increase muscle strength in healthy subjects. We hypothesized that, given RS hyperexcitability in stroke survivors, SAS could increase muscle strength in stroke survivors. The objective was to quantify the effect of SAS on maximal and sub-maximal voluntary elbow flexion on the contralesional (impaired) side in stroke survivors as compared to ipsilesional (non-impaired) side and healthy controls.
Thirteen hemiparetic stroke survivors and 12 healthy subjects volunteered for this investigation. Acoustic stimulation was given at rest, during ballistic maximal and sustained sub-maximal isometric elbow contractions using low (80 dB) and high intensity sound (105 dB). The effect of acoustic stimuli was evaluated from EMG and force recordings.
Prevalence of acoustic startle reflex with shorter latency in the impaired biceps was greater as compared to the response in the non-impaired side of stroke subjects and in healthy subjects. Delivery of SAS resulted in earlier initiation of elbow flexion and greater peak torque in healthy subjects and in stroke subjects with spastic hemiplegia during maximal voluntary elbow flexion tasks. During sub-maximal elbow flexion tasks, SAS-induced force responses were slightly greater on the impaired side than the non-impaired side. However, no statistically significant difference was found in SAS-induced responses between impaired and non-impaired sides at maximal and sub-maximal elbow flexion tasks.
The findings suggest RS hyperexcitability in stroke survivors with spastic hemiplegia. The results of similar SAS-induced responses between healthy and stroke subjects indicate that RS projections via acoustic stimulation are not likely to contribute to muscle strength for stroke survivors to a significant extent.
通过激活网状脊髓（RS）通路，惊声刺激（SAS）已被证明可增强健康受试者的肌肉力量。我们推测，鉴于中风幸存者存在RS兴奋性过高的情况，SAS可能会增强中风幸存者的肌肉力量。目的是量化与同侧（未受损）侧和健康对照相比，SAS对中风幸存者对侧（受损）侧最大和次最大自主肘关节屈曲的影响。
13名偏瘫中风幸存者和12名健康受试者自愿参与本研究。在静息状态下、进行弹道式最大和持续次最大等长肘关节收缩期间，使用低强度（80分贝）和高强度声音（105分贝）给予声刺激。从肌电图和力量记录评估声刺激的效果。
与中风受试者未受损侧和健康受试者的反应相比，受损肱二头肌中潜伏期较短的听觉惊吓反射发生率更高。在最大自主肘关节屈曲任务期间，对健康受试者和痉挛性偏瘫中风受试者进行SAS可导致更早开始肘关节屈曲和更大的峰值扭矩。在次最大肘关节屈曲任务期间，SAS诱发的力量反应在受损侧略大于未受损侧。然而，在最大和次最大肘关节屈曲任务中，受损侧和未受损侧之间的SAS诱发反应未发现统计学显著差异。
研究结果表明痉挛性偏瘫中风幸存者存在RS兴奋性过高的情况。健康受试者和中风受试者之间类似的SAS诱发反应结果表明，通过声刺激的RS投射不太可能在很大程度上有助于中风幸存者的肌肉力量。
