Primary sensory and motor cortex function in response to acute muscle pain: A systematic review and meta‐analysis

Abstract

Acute muscle pain has both motor and sensory consequences, yet the effect of muscle pain on the primary sensory (S1) and motor (M1) cortices has yet to be systematically evaluated. Here we aimed to determine the strength of the evidence for (1) altered activation of S1/ M1 during and after pain, (2) the temporal profile of any change in activation and (3) the relationship between S1/M1 activity and the symptoms of pain. In September 2015, five electronic databases were systematically searched for neuroimaging and electrophysiological studies investigating the effect of acute experimental muscle pain on S1/ M1 in healthy volunteers. Demographic data, methodological characteristics and primary outcomes for each study were extracted for critical appraisal. Meta-analyses were performed where appropriate. Twenty-five studies satisfied the inclusion criteria. There was consistent evidence from fMRI for increased S1 activation in the contralateral hemisphere during pain, but insufficient evidence to determine the effect at M1. Meta-analyses of TMS and EEG data revealed moderate to strong evidence of reduced S1 and corticomotor excitability during and following the resolution of muscle pain. A comprehensive understanding of the temporal profile of altered activity in S1/M1, and the relationship to symptoms of pain, is hampered by differences in methodological design, pain modality and pain severity between studies. Overall, the findings of this review indicate reduced S1 and corticomotor activity during and after resolution of acute muscle pain, mechanisms that could plausibly underpin altered sensorimotor function in pain. What does this review add?: We provide the first systematic evaluation of the primary sensory (S1) and motor (M1) cortex response to acute experimental muscle pain in healthy volunteers. We present evidence from a range of methodologies to provide a comprehensive understanding of the effect of pain on S1/M1. Through meta-analyses we evaluate the strength of evidence concerning the direction and temporal profile of the S1/M1 response to acute muscle pain.

Sensory Disturbances, but Not Motor Disturbances, Induced by Sensorimotor Conflicts Are Increased in the Presence of Acute Pain

“…In light of that theory, our results would be interpreted as indicating that acute pain alters body image (perceptual judgment), but without impacting on body schema. This suggests that some sensorimotor integration processes remain intact in the presence of pain which allows us to maintain adaptive motor behavior, a view supported by two recent studies showing that acute pain does not interfere with sensorimotor integration as measured by short afferent inhibition paradigm (Burns et al, 2016; Mercier et al, 2016). However, it is possible that pain of a longer duration is needed to impact on body schema, given that movement disorders become more prevalent in complex regional pain syndrome as the disease progresses (Van Hilten, 2010).…”

Unravelling the effect of experimental pain on the corticomotor system using transcranial magnetic stimulation and electroencephalography

“…Several neuroimaging studies have shown that experimental pain can affect the activity of the motor cortex (Apkarian et al 2000; Tracey et al 2000; Burns et al 2016). For the most part, these studies were done using functional magnetic resonance imaging (fMRI).…”

“…A few neuroimagery studies have also reported an increase in the activity of the primary motor cortex (M1) in the presence of experimental pain (Apkarian et al 2000; Tracey et al 2000; Burns et al 2016). Stancák et al demonstrated, using electroencephalography (EEG), that the application of a short-lasting painful heat stimuli on the hand decreased the β activity of the sensorimotor cortex (Stancák et al 2007).…”

Effect of Experimental Cutaneous Hand Pain on Corticospinal Excitability and Short Afferent Inhibition

“…It would be of interest in further studies to assess both pain-induced modulation in S1 excitability and SAI given the results of recent studies showing that a decrease in S1 excitability induced by non-invasive stimulation results in a reduction of the amount of SAI. At this stage, the impact of nociceptive stimuli on S1 excitability (as measured by the short latency components of somatosensory evoked potentials) remains unclear, especially for cutaneous nociceptive modalities [30,31,40,41,42,43,44,45]. One also needs to consider that the nociceptive modality and the location of the nociceptive stimuli with respect to the tested muscle might influence the results.…”