S1 Brain Connectivity in Carpal Tunnel Syndrome Underlies Median Nerve and Functional Improvement Following Electro-Acupuncture

Abstract

Carpal Tunnel Syndrome (CTS) is a median nerve entrapment neuropathy that alters primary somatosensory cortex (S1) organization. While electro-acupuncture (EA), a form of peripheral neuromodulation, has been shown to improve clinical and neurophysiological CTS outcomes, the role of EA-evoked brain response during therapy (within and beyond S1) for improved outcomes is unknown. We investigated S1-associated whole brain fMRI connectivity during both a resting and sustained EA stimulation state in age-matched healthy controls (N = 28) and CTS patients (N = 64), at baseline and after 8 weeks of acupuncture therapy (local, distal, or sham EA). Compared to healthy controls, CTS patients at baseline showed decreased resting state functional connectivity between S1 and thalamic pulvinar nucleus. Increases in S1/pulvinar connectivity strength following verum EA therapy (combined local and distal) were correlated with improvements in median nerve velocity (r = 0.38, p = 0.035). During sustained local EA, compared to healthy controls, CTS patients demonstrated increased functional connectivity between S1 and anterior hippocampus (aHipp). Following 8 weeks of local EA therapy, S1/aHipp connectivity significantly decreased and greater decrease was associated with improvement in patients' functional status (r = 0.64, p = 0.01) and increased median nerve velocity (r = −0.62, p = 0.013). Thus, connectivity between S1 and other brain areas is also disrupted in CTS patients and may be improved following EA therapy. Furthermore, stimulus-evoked fMRI connectivity adds therapy-specific, mechanistic insight to more common resting state connectivity approaches. Specifically, local EA modulates S1 connectivity to sensory and affective processing regions, linked to patient function and median nerve health.

Hotspots and Trends in Research on Treating Pain with Electroacupuncture: A Bibliometric and Visualization Analysis from 1994 to 2022

“… 79 Clinical trials suggest that EA’s mechanism for carpal tunnel syndrome potentially involves reshaping the white matter microstructure in the primary somatosensory cortex, concurrently enhancing functional connectivity between the primary somatosensory area and regions associated with emotional processing. 80 , 81 For chronic pain conditions such as fibromyalgia, EA can regulate primary somatosensory function linked with insular neurochemistry, thereby alleviating pain severity. 82 In summary, the limbic system may be the key area where acupuncture works.…”

Das komplexe regionale Schmerzsyndrom (CRPS) in der TCM

“…Letztere basiert auf der Spiegeltherapie, bei der die kontralaterale Seite unter Einsatz eines Spiegels behandelt wird, um die kortikale Plastizität zu modulieren. Unter Einsatz der funktionellen Magnetresonanztomografie konnte ein positiver Einfluss der Akupunktur auf kortikale Repräsentationszonen im Zusammenhang mit dem Karpaltunnelsyndrom nachgewiesen werden [13]. Die Behandlung sollte sich an zusätzlichen Symptomen sowie der Konstitution des Patienten orientieren.…”