PMID- 25229028 OWN - NLM STAT- PubMed-not-MEDLINE DCOM- 20140917 LR - 20211021 IS - 2234-0645 (Print) IS - 2234-0653 (Electronic) IS - 2234-0645 (Linking) VI - 38 IP - 4 DP - 2014 Aug TI - Evaluating the differential electrophysiological effects of the focal vibrator on the tendon and muscle belly in healthy people. PG - 494-505 LID - 10.5535/arm.2014.38.4.494 [doi] AB - OBJECTIVE: To investigate the electrophysiological effects of focal vibration on the tendon and muscle belly in healthy people. METHODS: The miniaturized focal vibrator consisted of an unbalanced mass rotating offset and wireless controller. The parameters of vibratory stimulation were adjusted on a flat rigid surface as 65 microm at 70 Hz. Two consecutive tests on the different vibration sites were conducted in 10 healthy volunteers (test 1, the Achilles tendon; test 2, the muscle belly on the medial head of the gastrocnemius). The Hoffman (H)-reflex was measured 7 times during each test. The minimal H-reflex latency, maximal amplitude of H-reflex (Hmax), and maximal amplitude of the M-response (Mmax) were acquired. The ratio of Hmax and Mmax (HMR) and the vibratory inhibition index (VII: the ratio of the Hmax after vibration and Hmax before vibration) were calculated. The changes in parameters according to the time and site of stimulation were analyzed using the generalized estimating equation methods. RESULTS: All subjects completed the two tests without serious adverse effects. The minimal H-reflex latency did not show significant changes over time (Wald test: chi(2)=11.62, p=0.07), and between the two sites (chi(2)=0.42, p=0.52). The changes in Hmax (chi(2)=53.74, p<0.01), HMR (chi(2)=20.49, p<0.01), and VII (chi(2)=13.16, p=0.02) were significant over time with the adjustment of sites. These parameters were reduced at all time points compared to the baseline, but the decrements reverted instantly after the cessation of stimulation. When adjusted over time, a 1.99-mV decrease in the Hmax (chi(2)=4.02, p=0.04) and a 9.02% decrease in the VII (chi(2)=4.54, p=0.03) were observed when the muscle belly was vibrated compared to the tendon. CONCLUSION: The differential electrophysiological effects of focal vibration were verified. The muscle belly may be the more effective site for reducing the H-reflex compared to the tendon. This study provides the neurophysiological basis for a selective and safe rehabilitation program for spasticity management with focal vibration. FAU - Lee, Gangpyo AU - Lee G AD - Department of Rehabilitation Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea. FAU - Cho, Yung AU - Cho Y AD - Department of Rehabilitation Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea. FAU - Beom, Jaewon AU - Beom J AD - Department of Rehabilitation Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea. FAU - Chun, Changmook AU - Chun C AD - Center for Bionics, Biomedical Research Institute, Korea Institute of Science and Technology, Seoul, Korea. FAU - Kim, Choong Hyun AU - Kim CH AD - Center for Bionics, Biomedical Research Institute, Korea Institute of Science and Technology, Seoul, Korea. FAU - Oh, Byung-Mo AU - Oh BM AD - Department of Rehabilitation Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea. LA - eng PT - Journal Article DEP - 20140828 PL - Korea (South) TA - Ann Rehabil Med JT - Annals of rehabilitation medicine JID - 101573065 PMC - PMC4163589 OTO - NOTNLM OT - Electrophysiology OT - H-reflex OT - Monosynaptic reflex OT - Muscle spasticity OT - Vibration COIS- No potential conflict of interest relevant to this article was reported. EDAT- 2014/09/18 06:00 MHDA- 2014/09/18 06:01 PMCR- 2014/08/01 CRDT- 2014/09/18 06:00 PHST- 2013/07/26 00:00 [received] PHST- 2014/01/29 00:00 [accepted] PHST- 2014/09/18 06:00 [entrez] PHST- 2014/09/18 06:00 [pubmed] PHST- 2014/09/18 06:01 [medline] PHST- 2014/08/01 00:00 [pmc-release] AID - 10.5535/arm.2014.38.4.494 [doi] PST - ppublish SO - Ann Rehabil Med. 2014 Aug;38(4):494-505. doi: 10.5535/arm.2014.38.4.494. Epub 2014 Aug 28.