Acupuncture-induced changes in functional connectivity of the primary somatosensory cortex varied with pathological stages of Bell’s palsy

Abstract

Bell’s palsy is the most common cause of acute facial nerve paralysis. In China, Bell’s palsy is frequently treated with acupuncture. However, its efficacy and underlying mechanism are still controversial. In this study, we used functional MRI to investigate the effect of acupuncture on the functional connectivity of the brain in Bell’s palsy patients and healthy individuals. The patients were further grouped according to disease duration and facial motor performance. The results of resting-state functional MRI connectivity show that acupuncture induces significant connectivity changes in the primary somatosensory region of both early and late recovery groups, but no significant changes in either the healthy control group or the recovered group. In the recovery group, the changes also varied with regions and disease duration. Therefore, we propose that the effect of acupuncture stimulation may depend on the functional connectivity status of patients with Bell’s palsy.

Functional Connectivity Changes of Primary Somatosensory Cortex in Response to the Acupuncture in Bell’s Palsy Patients

“…It has been verified that the acupuncture played an important role in ameliorating the blepharospasm in non-lesioned side [15,16]. We suggested that the alteration in non-lesioned side SI connectivity might be the result of reductions of the abnormal brain activity tendencies [5,10].…”

“…Our previous studies have also shown that the acupuncture leads to significant connectivity change. In addition, several investigations suggest the brain's responses to acupuncture depend on the functional connectivity status and that some functional reorganizations of special cortical regions are important in the process of BP recovery [5,9,10]. Thus, we believed that different effects of acupuncture made on the bilateral Hegu points would be revealed by comparing functional connectivity alterations.…”

“…Although the factor of whether the data were flipped was considered in the group analysis [7], it also could cause several bias due to the asymmetry of cerebral anatomy and function. Therefore, further studies should control these relevant variables strictly to make the conclusion more convincing [5,9].…”

“…DMN is a network relating several brain regions while its major function is to increase the interaction among these regions [21]. According to a previous study, altering connectivity of DMN-related areas can modulate homeostasis to help recovering from BP [5]. PCC, located in the backmost part of cingulate cortex, is a key node in DMN.…”

“…Finally, the impulse would be transmitted to the cerebral cortex and lead to cerebral activation [4]. A possible consideration of choosing Hegu for treating BP is that the representative cortical areas of the face and hands are adjacent in the primary motor area (MI) and the primary somatosensory area (SI) [5]. In BP patients, the cortical reacting field of hands extends laterally and enlarges into the site of facial regions in SI [6].…”