Effect of Acupuncture at Right HoKu Point on the Bilateral Vibration-Induced Finger Flexion Reflex in Man

Abstract

Vibration applied to the volar side of the finger tip has been reported to induce finger flexion reflex. Acupuncture is reported to inhibit this vibration-induced finger flexion reflex (VFR) in the ipsilateral hand. The purpose of this study was to investigate the effect of unilateral acupuncture in the hand on VFR in both hands. As no systematic study on the relationship between VFR and the force of voluntary contraction with no vibration (Initial Force: IF) has been reported, this relationship was studied prior to the present study on acupuncture. VFR was induced by mechanical vibration on the volar side of the middle finger tip with 10 g to 500 g IF. With approximately 300 g IF, VFR was consistent. Therefore, approximately 300 g IF was applied for VFR induction to study the effect of acupuncture on VFR. A stainless steel needle was inserted into the right Hoku point and remained inserted (in-situ technique) for 10 minutes. VFR in both hands was significantly decreased by acupuncture at the right Hoku point (% control force of VFR: right, 67.8%; left, 74.6%). The present results suggest that acupuncture in the unilateral hand influences the bilateral reflex arc of VFR.

Inhibitory Effect of Pain-Eliciting Transcutaneous Electrical Stimulation on Vibration-Induced Finger Flexion Reflex in the Human Upper Limb

“…Several lines of study show that Inhibitory Effect of Pain-Eliciting Transcutaneous Electrical Stimulation this innocuous-stimulation-induced flexion reflex is inhibited by acupuncture with needle penetration [7][8][9][20][21][22][23][24]. Furthermore, when stimulation intensity by acupuncture is greater, the inhibitory effect over VFR is also greater [8].…”

“…Along with pain-eliciting TES, VFR inhibition was observed not only during needle insertion, but also subsequently [3,[7][8][9][20][21][22][23]. This characteristic of inhibition implies that acupuncture inhibits motoneuronal activities of VFR reflex circuits just as pain-eliciting TES does.…”

“…We previously reported the inhibitory effects of noxious mechanical stimulation of a needle insertion, namely acupuncture, in the upper limb on VFR [3,[7][8][9]. Needle penetration is a noxious stimulus [10].…”

Inhibitory Effect of Needle Penetration on Vibration-Induced Finger Flexion Reflex in Humans

“…Subjects then pressed the pressure transducer lightly as a background contraction. When the background contraction became stable, 60 Hz vibration with 1 mm displacement amplitude was applied to the volar side of the middle fingertip for 20 s 6–12. Vibration was delivered using an electromagnetic vibrator (FF 225N; Foster Electric Co, Ltd) driven by a sine-pulse generator (VP-7421A Function Generator; Matsushita Electrical Industrial Co, Ltd) coupled to a power amplifier (1706; Bose Corp).…”

“…Force measurements were then recorded using a BioLog (DL-1000; S&ME, Inc) through an amplifier (DL-170; S&ME, Inc), with EMG analyser software (m-Scope; S&ME, Inc) installed in the PC (PC-VY12MEX84EHM NEC). We measured maximum FF force of VFR during vibratory stimulation according to previous studies 2 6–9. We also measured the AUC of FF force during vibratory stimulation and simultaneously recorded the surface EMG in the flexor muscles.…”