Acupuncture-Evoked Response in Somatosensory and Prefrontal Cortices Predicts Immediate Pain Reduction in Carpal Tunnel Syndrome

Abstract

The linkage between brain response to acupuncture and subsequent analgesia remains poorly understood. Our aim was to evaluate this linkage in chronic pain patients with carpal tunnel syndrome (CTS). Brain response to electroacupuncture (EA) was evaluated with functional MRI. Subjects were randomized to 3 groups: (1) EA applied at local acupoints on the affected wrist (PC-7 to TW-5), (2) EA at distal acupoints (contralateral ankle, SP-6 to LV-4), and (3) sham EA at nonacupoint locations on the affected wrist. Symptom ratings were evaluated prior to and following the scan. Subjects in the local and distal groups reported reduced pain. Verum EA produced greater reduction of paresthesia compared to sham. Compared to sham EA, local EA produced greater activation in insula and S2 and greater deactivation in ipsilateral S1, while distal EA produced greater activation in S2 and deactivation in posterior cingulate cortex. Brain response to distal EA in prefrontal cortex (PFC) and brain response to verum EA in S1, SMA, and PFC were correlated with pain reduction following stimulation. Thus, while greater activation to verum acupuncture in these regions may predict subsequent analgesia, PFC activation may specifically mediate reduced pain when stimulating distal acupoints.

Sham Electroacupuncture Methods in Randomized Controlled Trials

“…Among them, 5 studies29549095107 were published between 1992 and 1999; 33 studies22242527303138454752535657586768717273747778818384929397104105106110111 were published between 2000 and 2010; the remaining 56 studies1819202123262832333435363739404142434446484950515559606162636465666970757679808285868788899194969899100101102103108109 were reported from 2010 to 2015 (Fig. 2).…”

“…2). Indications for EA included pain (32 studies)1819212426273133363740424547515256606667727682848890929697103110111, anesthesia (8 studies)46507374868994102, stroke (7 studies)2528293462105106, depression (6 studies)235359656880, obesity (4 studies)32495470, primary dysmenorrheal/menstrual pain (4 studies)619899101, substance abuse (heroin or smoking) (3 studies)6495107, osteoarthritis (2 studies)22104, migraine (2 studies)3978, nausea and vomiting (2 studies)3857, postoperative ileus (2 studies)3591, insomnia (2 studies)6381, benign prostate hyperplasia (2 studies)7987, diabetic mellitus related diseases (2 studies)83109, carpal tunnel syndrome (1 study)100, rheumatoid arthritis (1 study)93, whiplash-associated disorders (1 study)69, constipation (1 study)48, multiple sclerosis (1 study)41, tinnitus (1 study)20, auditory hallucination (1 study)30, attention deficit hyperactivity disorder (1 study)…”

“…EA treatment alone was adopted in 55 trials1920212223242526282930313435363738394243535558606166686971727577787980838485868788899091959899100101103104107108110111, while the interventions of the remaining 39 trials were a combination of EA and western conventional medicine (WCM). Four trials244754100 were designed as two groups of EA, and seven trials384361639899101 were conducted with two groups of sham EA.…”

“…Four trials244754100 were designed as two groups of EA, and seven trials384361639899101 were conducted with two groups of sham EA. Compared with sham EA group, real EA group in 83 studies selected the same number of acupoints; nine studies2546668990105106108111 used more number of acupoints; one study20 used less number of acupoints; one study52 did not report the number of acupoints.…”

“…Eight studies26495476959697110 identified acupoints by using a point detector. The “ deqi ” sensation was required in 65 real EA groups181920212223242526293031333435363940414344474850515657585960616263646667697175777879808182838586879091939899100101102104105106109111 and 3 sham EA groups selected nonspecific acupoints6178101. Eight studies utilized pricking sensation to mimic needle sensation and blind participants in control group2021235260636781.…”