Bradnam Lynley, Shanahan E Michael, Hendy Kirsty, Reed Amalia, Skipworth Tegan, Visser Anri, Lennon Sheila
Discipline of Physiotherapy, School of Health Sciences, Faculty of Medicine, Nursing and Health Sciences, Flinders University, South Australia, Australia; Applied Brain Research Laboratory, Centre for Neuroscience, School of Medicine, Faculty of Medicine, Nursing and Health Sciences, Flinders University, South Australia, Australia.
Department of Rheumatology, Repatriation General Hospital, Adelaide, South Australia, Australia; School of Medicine, Faculty of Medicine, Nursing and Health Sciences, Flinders University, South Australia, Australia.
Clin Neurophysiol. 2016 Jan;127(1):769-778. doi: 10.1016/j.clinph.2015.03.012. Epub 2015 Apr 4.
To characterise short afferent inhibition (SAI) and the cortical silent period (CSP) in the primary motor cortex representations of the infraspinatus muscle in healthy adults and people experiencing chronic shoulder pain, to determine the impact of a suprascapular nerve block (SSNB).
Neurophysiological measures were obtained in 18 controls and 8 patients with chronic shoulder pain, pre and post SSNB and 1 week later. Pain intensity was assessed by a visual analogue scale.
SAI was apparent in controls (all P<0.03) and a CSP was observed which reduced in the presence of SAI (all P<0.0001). Compared to controls, shoulder pain patients demonstrated higher active motor threshold (P=0.046), less SAI (P=0.044), a longer CSP (P=0.048) and less modulation of the CSP by SAI (P=0.045). Higher motor thresholds were related to higher pain scores (P=0.009). The SSNB immediately restored SAI (P=0.013), with a positive relationship between increased SAI and reduced pain (P=0.031). The SSNB further reduced modulation of CSP by SAI at 1 week post injection (P=0.006).
SAI and the CSP were present and demonstrated robust interaction in controls, which was aberrant in patients. The SSNB transiently restored SAI but had no effect on the CSP; however CSP modulation by SAI was further attenuated 1 week post injection.
The current findings improve understanding of the neurophysiology of the shoulder motor cortex and its modulation by chronic pain. The effect of SSNB in shoulder pain patients should be interpreted with caution until proven in a larger population. Interventions that target intracortical inhibition might increase efficacy in people with chronic shoulder pain.
对健康成年人及慢性肩痛患者冈下肌在初级运动皮层代表区的短潜伏期传入抑制（SAI）和皮层静息期（CSP）进行特征描述，以确定肩胛上神经阻滞（SSNB）的影响。
对18名对照者和8名慢性肩痛患者在SSNB前、后及1周后进行神经生理学测量。采用视觉模拟量表评估疼痛强度。
SAI在对照者中明显存在（所有P<0.03），并观察到CSP，在SAI存在时CSP缩短（所有P<0.0001）。与对照者相比，肩痛患者表现出更高的主动运动阈值（P=0.046）、更少的SAI（P=0.044）、更长的CSP（P=0.048）以及SAI对CSP的调节作用更小（P=0.045）。更高的运动阈值与更高的疼痛评分相关（P=0.009）。SSNB立即恢复了SAI（P=0.013），SAI增加与疼痛减轻之间呈正相关（P=0.031）。注射后1周，SSNB进一步降低了SAI对CSP的调节作用（P=0.006）。
SAI和CSP在对照者中存在并表现出强大的相互作用，而在患者中则异常。SSNB短暂恢复了SAI，但对CSP无影响；然而，注射后1周SAI对CSP的调节作用进一步减弱。
目前的研究结果有助于增进对肩部运动皮层神经生理学及其受慢性疼痛调节的理解。在更大规模人群中得到证实之前，应谨慎解释SSNB对肩痛患者的影响。针对皮层内抑制的干预措施可能会提高慢性肩痛患者治疗的有效性。
