Subclinical Neck Pain Leads to Differential Changes in Early Somatosensory Evoked Potentials in Response to a Novel Force Matching Tracking Task

Abstract

Background: Neural adaptions in response to sensorimotor tasks are impaired in those with untreated, recurrent mild-to-moderate neck pain (subclinical neck pain (SCNP)), due to disordered central processing of afferent information (e.g., proprioception). Neural adaption to force modulation, a sensorimotor skill reliant on accurate proprioception, is likely to be impaired in those with SCNP. This study examined changes in somatosensory evoked potential (SEP) peak amplitudes following the acquisition of a novel force matching tracking task (FMTT) in those with SCNP compared to non-SCNP. Methods: 40 (20 female (F) & 20 male (M); average age (standard deviation, SD): 21.6 (3.01)) right-handed participants received controlled electrical stimulation at 2.47 Hz and 4.98 Hz (averaged 1000 sweeps/frequency) over the right-median nerve, to elicit SEPs before and after FMTT acquisition. Participants used their right thumb to match a series of force profiles that were calibrated to their right thumb (abductor pollicis brevis muscle) strength. To determine if motor learning was impacted, retention was assessed 24 to 48 hours later. Outliers were removed before running independent t-tests on normalized SEP peak amplitudes, and repeated measures analysis of variance (ANOVA) with planned contrasts on absolute and normalized motor performance accuracy. Benjamini-hochberg test was used to correct for multiple independent SEP comparisons. Results: SEP peaks: N18 (t(29.058) = 2.031, p = 0.026), N20 (t(35) = –5.460, p < 0.001), and P25 (t(33) = –2.857, p = 0.004) had group differences. Motor performance: Absolute error (n = 38) had a main effect of time, and significant pre-and post-acquisition contrast for time (both p < 0.001). Conclusions: Group differences in the olivary-cerebellar pathway (N18), and cortical processing at the somatosensory cortex (N20 and P25), suggests that SCNP alters cortical and cerebellar processing compared to non-SCNP in response to FMTT acquisition. The sensory-motor integration differences in the SCNP group suggests that those with SCNP may rely more on feedback loops for discrete sensorimotor tasks dependent on proprioception. Early SEP changes may be used as a marker for altered neuroplasticity in the context of motor skill acquisition of a novel discrete FMTT in those with SCNP.

Development of the Sensory–Motor Dysfunction Questionnaire and Pilot Reliability Testing

“…Each of these 9 items consisted of constructs of SMI, MMI, and motor control that have been documented in the literature and have also been shown to change following treatment of vertebral dysfunction. The items that were included pertained to balance [ 65 , 66 ], hand–eye coordination [ 41 ], head or full-body proprioception [ 45 , 51 , 55 ], reaching movement, grasping motion [ 67 ], motor performance [ 46 , 48 , 52 , 53 ], audio or visual processing, MMI [ 47 , 49 ], and motor performance during the processing of multi-modal stimuli [ 49 ].…”

“…SCSP individuals have pain-free days and have not sought treatment [ 44 , 45 ] due to the recurrent nature of their pain. As a result, SCSP populations have been frequently utilized [ 44 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 ] to study how altered paraspinal afferent input may impact the CNS without the confounding effects of current pain [ 44 , 45 ], i.e., asymptomatic on the day of testing. This is important because acute pain is known to affect early somatosensory evoked potentials [ 56 , 57 , 58 ] and the presence of pain of any chronicity is also known to alter movement patterns [ 33 , 59 ].…”