Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, 236 Irvine Hall, Athens, OH 45701, USA.
BMC Musculoskelet Disord. 2011 Jul 22;12:170. doi: 10.1186/1471-2474-12-170.
While there is growing evidence for the efficacy of SM to treat LBP, little is known on the mechanisms and physiologic effects of these treatments. Accordingly, the purpose of this study was to determine whether SM alters the amplitude of the motor evoked potential (MEP) or the short-latency stretch reflex of the erector spinae muscles, and whether these physiologic responses depend on whether SM causes an audible joint sound.
We used transcranial magnetic stimulation to elicit MEPs and electromechanical tapping to elicit short-latency stretch reflexes in 10 patients with chronic LBP and 10 asymptomatic controls. Neurophysiologic outcomes were measured before and after SM. Changes in MEP and stretch reflex amplitude were examined based on patient grouping (LBP vs. controls), and whether SM caused an audible joint sound.
SM did not alter the erector spinae MEP amplitude in patients with LBP (0.80±0.33 vs. 0.80±0.30 μV) or in asymptomatic controls (0.56±0.09 vs. 0.57±0.06 μV). Similarly, SM did not alter the erector spinae stretch reflex amplitude in patients with LBP (0.66±0.12 vs. 0.66±0.15 μV) or in asymptomatic controls (0.60±0.09 vs. 0.55±0.08 μV). Interestingly, study participants exhibiting an audible response exhibited a 20% decrease in the stretch reflex (p<0.05).
These findings suggest that a single SM treatment does not systematically alter corticospinal or stretch reflex excitability of the erector spinae muscles (when assessed~10-minutes following SM); however, they do indicate that the stretch reflex is attenuated when SM causes an audible response. This finding provides insight into the mechanisms of SM, and suggests that SM that produces an audible response may mechanistically act to decrease the sensitivity of the muscle spindles and/or the various segmental sites of the Ia reflex pathway.
虽然有越来越多的证据表明 SM 治疗 LBP 的疗效，但对于这些治疗的机制和生理效应知之甚少。因此，本研究的目的是确定 SM 是否改变竖脊肌运动诱发电位（MEP）或短潜伏期牵张反射的幅度，以及这些生理反应是否取决于 SM 是否引起可听见的关节声音。
我们使用经颅磁刺激来引出 MEP，用电机械敲击来引出竖脊肌的短潜伏期牵张反射，在 10 名慢性 LBP 患者和 10 名无症状对照者中进行。在 SM 前后测量神经生理结果。根据患者分组（LBP 与对照组）以及 SM 是否引起可听见的关节声音，检查 MEP 和牵张反射幅度的变化。
SM 并未改变 LBP 患者（0.80±0.33 与 0.80±0.30 μV）或无症状对照组（0.56±0.09 与 0.57±0.06 μV）竖脊肌 MEP 幅度。同样，SM 也未改变 LBP 患者（0.66±0.12 与 0.66±0.15 μV）或无症状对照组（0.60±0.09 与 0.55±0.08 μV）竖脊肌牵张反射幅度。有趣的是，表现出可听见反应的研究参与者的牵张反射幅度降低了 20%（p<0.05）。
这些发现表明，单次 SM 治疗不会系统地改变竖脊肌的皮质脊髓或牵张反射兴奋性（在 SM 后~10 分钟评估时）；然而，它们确实表明，当 SM 引起可听见的反应时，牵张反射会减弱。这一发现为 SM 的机制提供了深入了解，并表明产生可听见反应的 SM 可能通过机械作用降低肌肉梭的敏感性和/或 Ia 反射通路的各种节段部位的敏感性。
