Changes in Cerebral Cortex Activation During Upright Standing Tasks in Individuals with Chronic Neck Pain: An fNIRS Study

Chongwu Xiao ¹ Qianfei Liang ¹ Yugang Yang ¹ Mingyu Mo ¹ Weixiong Li ¹ Huade Chen ¹ Yaobin Long ^1* Jinjun Huang ^2*

• ¹ Department of Rehabilitation, Second Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Region, China
• ² Department of Rehabilitation，Guiping People's Hospital, Guiping, China

Introduction: Studies show that individuals with chronic neck pain (CNP) exhibit postural control deficits. However, the neural mechanisms underlying these deficits in CNP remain unexplored. Therefore, this study aimed to investigate the neural activity using functional near-infrared spectroscopy (fNIRS), providing insights into the central mechanism underlying postural control deficits in CNP.In this cross-sectional study, 10 individuals with CNP (CNP group) and 10 healthy controls (HC group) were assessed under three conditions: Task 1, standing on a force plate with eyes open and both feet; Task 2, standing on a force plate with eyes closed and both feet; Task 3, standing on a force plate with eyes closed and one foot. Cortical activation, including bilateral prefrontal cortex (PFC), dorsolateral prefrontal cortex, pre-motor cortex and supplementary motor area (PMC/SMA), primary motor cortex (M1), and primary somatosensory cortex (S1) were measured using fNIRS. Balance parameters, including the sway area, total sway length, mean velocity, and center of pressure (COP) amplitude in the anterior-posterior (AP) and medial-lateral (ML) directions, were measured using a force plate. In Tasks 1 and 2, no differences were observed between both groups in balance parameters. However, the CNP group exhibited significantly higher activation in the left PMC/SMA (F = 4.788, P = 0.042) and M1 (F = 9.598, P = 0.006) in Task 1 and lower activation in the left (F = 4.952, P = 0.039) and right (F = 6.035, P = 0.024) PFC in Task 2. In Task 3, the CNP group exhibited a significantly larger COP amplitude in the AP direction (F = 7.057, P = 0.016). Additionally, activation in the right M1 (F = 7.873, P = 0.012) was significantly higher than in the HC group. Correlation analysis in Task 3 revealed stronger associations between the parameters in the CNP group.Our findings suggest that individuals with CNP exhibit distinct patterns of cortical activities and postural control deficits. The PFC, M1, and PMC/SMA were involved in maintaining upright standing balance, and cerebral cortex changes associated with upright standing balance provide a more sensitive indicator of postural control deficits than peripheral balance parameters in individuals with CNP.