The overall aim of the proposed study is to determine optimal parameter of focal muscle vibration for improving spasticity and identify neurophysiological mechanism in healthy subjects. In investigation I-1, subjects will undergo focal muscle vibration with 40, 80, 120 Hz frequency at the medial gastrocnemius muscles (mGCM). As a surrogate maker of spasticity, H-reflex and compound motor action potential (CMAP) of the tibial nerve at mGCM will be recorded pre, during, and post vibration. In investigation I-2, subjects will undergo focal muscle vibration with 0.1, 0.3, 0.5 mm amplitude at mGCM. H-reflex and CMAP of the tibial nerve at mGCM will be recorded pre, during, and post vibration. In investigation II, subjects will undergo focal muscle vibration with predetermined parameters by the investigation I at mGCM. H-reflex and CMAP of the tibial nerve and motor evoked potential at mGCM will be recorded pre, during, and post vibration.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
17
Seoul National University Hospital
Seoul, South Korea
H/M ratio
The ratio of maximal H-reflex amplitude (mV) to CMAP amplitude (mV) recorded at mGCM
Time frame: baseline, 1, 5 and 10 minutes during vibration, and 1 and 5 minutes after vibration
H amplitude
maximal H-reflex amplitude (mV) recorded at mGCM
Time frame: baseline, 1, 5 and 10 minutes during vibration, and 1 and 5 minutes after vibration
M amplitude
CMAP amplitude (mV) recorded at mGCM
Time frame: baseline, 1, 5 and 10 minutes during vibration, and 1 and 5 minutes after vibration
motor evoked potential (MEP) amplitude
Transcranial magnetic stimulation on the contralateral leg motor cortex is used to measure MEP at mGCM.
Time frame: baseline, 10 minutes during vibration, and 5 minutes after vibration
Resting motor threshold (RMT)
Resting motor threshold (%) is defined as the minimal intensity of TMS capable of inducing MEPs greater than 100μV peak-to-peak amplitude in at least 3 of 5 trials.
Time frame: baseline, 10 minutes during vibration, and 5 minutes after vibration
Short interval intracortical inhibition
Short interval intracortical inhibition is recorded by using conditioning stimulus of 90% RMT and test stimulus of 120% RMT with 1ms interval.
Time frame: baseline, 10 minutes during vibration, and 5 minutes after vibration
Intracortical facilitation
Intracortical facilitation is recorded by using conditioning stimulus of 90% RMT and test stimulus of 120% RMT with 10ms interval.
Time frame: baseline, 10 minutes during vibration, and 5 minutes after vibration
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