Acupuncture is effective for the treatment of Bell’s palsy, a type of facial paralysis. Researchers at the Anhui Provincial Hospital of Traditional Chinese Medicine conducted an fMRI study analyzing the effects of acupuncture for the treatment of Bell’s palsy. Based on the data, the researchers conclude that acupuncture increases functional connectivity within the sensorimotor cortex and promotes brain reorganization in Bell’s palsy patients.  The researchers note that acupuncture directly restores neurosynaptic function and improves positive patient outcomes.
The study focused on the application of one distal acupuncture point, Hegu (LI4). The researchers selected this acupoint because prior investigations determined that it is effective in reversing facial paralysis in patients with Bell’s palsy and after a stroke.  According to Traditional Chinese Medicine (TCM) principles, LI4 is indicated for the treatment of face and mouth disorders. The MRI research confirms this ancient principle.
Anhui Provincial Hospital researchers (Yang et al.) compared fMRI brain scan results of healthy participants with Bell’s palsy patients. They comment on the effects of acupuncture, “The functional connectivity in the sensory motor cortex is enhanced in Bell’s palsy patients.” After acupuncture treatment, they observe that there is “increased functional connectivity” within the sensorimotor cortex, including the primary somatosensory cortex, secondary somatosensory cortex, primary motor cortex, and premotor cortex.
The primary somatosensory cortex (S1) is responsible for processing afferent somatosensory input and the secondary somatosensory cortex (S2) is involved in performing higher order functions (e.g., integration of sensorimotor signals). ,  The primary motor cortex (M1) plays a critical role in generating neural impulses and moving skeletal muscles.  The premotor cortex (PMC) is mainly responsible for the coordination of complex movements and is the more advanced center of the sensory motor cortex.  Acupuncture’s effects on these areas reveals the mechanisms involved in its ability to cure Bell’s palsy.
Hegu (LI4) is the Yuan-source point of the hand Yangming large intestine meridian. Hegu is located between metacarpal bones (first and second) and is at the midpoint of the radial side of the second metacarpal bone. The anatomical structure of Hegu contains skin, subcutaneous tissue, nerve branches (radial, ulnar, median), muscles (first dorsal interosseous, adductor pollicis, flexor pollicis brevis, abductor pollicis brevis), and vessels (dorsal vein network, radial artery end, thumb principal artery, deep palmar arch). 
The researchers cited the ancient historical roots supporting the use of Hegu in the study. In the acupuncture classic, the Zhen Jiu Jia Yi Jing (Systematized Canon of Acupuncture and Moxibustion), it is stated that “Hegu governs loss of use of the lips, deafness, blockage in the ear, and painful gums.” The Yu Long Jing (Jade Dragon Verse), a book written in the Chinese Yuan dynasty, notes that “Needling at Hegu can treat diseases in the head and face in a miracle-like and effective way.” The Zhen Jiu Ju Ying (Gathered Blooms of Acupuncture and Moxibustion) has a similar saying, “The Hegu point treats diseases in the face and mouth.” Now, modern research verifies the efficacy of Hegu for the treatment of Bell’s palsy.
The study was set up as a double-arm investigation. A total of 59 participants were treated and evaluated in the study. They were divided into two groups: facial paralysis and control. The facial paralysis group was composed of 35 patients diagnosed with Bell’s palsy from the Anhui Provincial Hospital of Traditional Chinese Medicine. The control group was composed of 24 healthy subjects. For both groups, the following selection criteria were applied:
- No history of mental illness or neurological diseases
- No history of taking mental illness or neurological drugs
- No primary and comorbid heart, liver, or kidney disease
The statistical breakdown for each group was as follows. The facial paralysis group had 20 males and 15 females (median age 35 years). The control group had 10 males and 14 females (median age 23 years). There were no significant statistical differences in sample volume, gender, and age relevant to patient outcome measures for patients initially admitted to the study.
Both groups received acupuncture treatment performed by an experienced licensed acupuncturist. After disinfection of the acupoint site, a disposable filiform needle was inserted into Hegu with a high needle entry speed, to a depth of 1.0 cm. Upon obtaining a deqi sensation, the needle was manually stimulated with Ping Bu Ping Xie (attenuating and tonifying) manipulation techniques at a frequency of 1 Hz during the needle retention time. Task and resting-state fMRI measurement were recorded at the following data points: before, during, and after acupuncture treatments.
Evaluations and Results
Before acupuncture treatment, the comparative analysis of the resting-state brain function between the facial paralysis group and the control group showed that both S1 and M1 have “increased functional connectivity” with the PMC in the superior frontal gyrus (SFG) and middle frontal gyrus (MFG) in Bell’s palsy sufferers. The research team has an explanation for this phenomenon. They note, “The enhanced functional connectivity between MI/SI and PMC in Bell’s palsy patients reflects a compensatory mechanism of the central nervous system.” They explain, “In Bell’s palsy patients, the muscles cannot perform the movement commands issued by M1 through the efferent nerves, while S1 cannot process afferent somatosensory signals to form a complete feedback loop with M1. Therefore, PMC, the more advanced center, activates its motor coordination function and acts as neural pathways to close the loop.”
After needling Hegu, bilateral S2 has “decreased functional connectivity” with the visual and auditory cortices and “increased functional connectivity” within the sensorimotor cortex including S1, S2, M1, and PMC. The researchers note, “Increased functional connectivity is associated with elevated neurosynaptic activity, which contributes to the reorganization of brain function.” They add, “Brain function reorganization based on synaptic plasticity of the central nervous system has been extensively studied and proved to be the neurophysiological basis for the recovery of stroke and Bell’s palsy (also known as peripheral facial paralysis) patients.” , 
The study indicates that needling Hegu produces positive patient outcomes in Bell’s palsy patients. In light of the findings, acupuncture is an important treatment option for patients with Bell’s palsy. Patients interested in learning more about treatment are recommended to contact local licensed acupuncturists.
 Yang J, Li CF, Zhang QP, Yuan AH, Xu CS, Zhu YF, Li LY, Zhao B. Preliminary Analysis of Brain Function Imaging in Patients with Bell’s Palsy Treated with Acupuncture at Hegu (LI4) [J]. Journal of Changchun University of Traditional Chinese Medicine, 2012,28(04):608-610.
 Cai YW, Pei J, Fu LH. Mechanism Research Progress of “Point LI 4 Treating Diseases in the Face and Mouth” Based on Functional Magenetic Resonance Imaging [J]. Global Traditional Chinese Medicine, 2017,10(11):1412-1416.
 Borich MR, Brodie SM, Gray WA, Ionta S, Boyd LA. “Understanding the role of the primary somatosensory cortex: Opportunities for rehabilitation.” Neuropsychologia. 2015;79(Pt B):246-255.
 Tzu Ling Chen, Claudio Babiloni, Antonio Ferretti, Mauro Gianni Perrucci, Gian Luca Romani, Paolo Maria Rossini, Armando Tartaro, Cosimo Del Gratta, Human secondary somatosensory cortex is involved in the processing of somatosensory rare stimuli: An fMRI study [J]. NeuroImage, 2008 May 1;40(4):1765-71.
 Kathleen K H, Jing Liu, Ovidiu M, et al. “The integrated response of the human cerebrocerebellar and limbic systems to acupuncture stimulation at ST 36 as evidenced by fMRI[J]” NeuroImage , 2005 , 27(3):479-496.
 Cui HR, Yang XD, Xu XD, et al. Local Anatomy of the Hegu Point [J]. Journal of Clinical Acupuncture and Moxibustion, 2006，22( 4) : 35-37.
 Grefkes C, Fink G R.Reorganization of cerebral networks after stroke :new insights from neuroimaging with connectivity approaches[ J] .Brain , 2011, 134(5):1264-1276.
 Klingner C M, Volk G F, Maertin A, et al. Cortical reorganization in Bell’ s palsy [J]. Restorative Neurology and Neuroscience, 2011 , 29(3):203-214.