Abstract
Purpose: Chiropractic plays an integral role in the conservative treatment and management of neuro-musculoskeletal conditions that cause pain. Clinically, the benefit of spinal manipulative therapy (SMT) for pain relief related to neuro-musculoskeletal causes is apparent, yet the underlying mechanisms responsible are still not clearly understood. A paucity of clinical research defining the neurophysiological effects of SMT leaves room for investigation. Several studies using experimentally induced pain have proposed that there are central and peripheral nervous system aspects involved in afferent input and modulation of pain (Bialosky et al., 2012; Brea-Rivero et al., 2018; Dorron et al., 2016). Therefore, this study assessed the potential role of SMT on the mechanisms of the nervous system that mediate pain. As the responses to mechanical stimuli were examined, both locally and remotely using pinprick sensitivity and pressure pain threshold with spinal manipulation applied, central modulation could be assessed. Aim: The aim of this study was to analyse the effects of cervical SMT on experimental mechanical pain, locally and remotely, in asymptomatic individuals. Mechanical pain was tested using an algometer for pressure pain threshold (PPT) and a Neuropen for pinprick sensitivity (PPS), before and after left- or right-sided cervical chiropractic manipulation was applied. Method: This was a single blinded, randomised study. One-hundred participants were included and divided into two even groups; group A (control group) and group B (intervention group). All participants were assessed for inclusion and exclusion criteria and subsequently readings were taken over time. Both groups had multiple readings taken using PPS and PPT devices at four locations. Group B had intervention (cervical spinal manipulation) applied after the first readings were taken. Data was thus recorded and analysed. vi Procedure: One hundred, randomly recruited, pain-free individuals participated in this study which took place at the University of Johannesburg (UJ), Chiropractic Day Clinic. The study required a once-off consultation in which each participant was informed and written consent collected followed by an assessment. Device recordings were subsequently taken. Two types of experimental stimuli, PPS and PPT, were tested for local and remote responses to changes in stimulus sensitivity. Pain threshold and sensitivity were measured at two points remotely on the bilateral medial calf and two points locally on the bilateral paraspinal muscles at the relative cervical spine level. This was carried out at three time intervals of 0-minutes (pre-intervention), 2-minutes (immediate post-intervention) and 10-minutes (post-intervention). Results: Cervical spine manipulation reduced deep pressure sensitivity significantly for the intervention group with local and remote effects noted over the ten minute time interval. It was also noted that cervical spine manipulation reduced pain sensitivity for superficial pinprick stimuli, with notable changes for the intervention group, both locally and remotely, over the ten minute time interval. Conclusion: Statistical and clinical changes were noted for pressure pain threshold and pinprick sensitivity for the intervention group who received spinal manipulation. These differences were noted at local and remote regions tested by the algometer and Neuropen. These findings suggest that cervical spine manipulation may have an effect on the central nervous system and pain modulation.
M.Tech. (Chiropractic)