Comparison of monophasic versus biphasic stimulation in rTMS over premotor cortex: SEP and SPECT studies.
OBJECTIVE
To optimize the clinical uses of repetitive transcranial magnetic stimulation (rTMS), we compared the effects of rTMS on somatosensory-evoked potentials (SEPs) and regional cerebral blood flow (rCBF) using different phases (monophasic vs. biphasic) or frequencies (0.2Hz vs. 0.8Hz) of stimulation.


METHODS
In the first experiment, different phases were compared (0.2Hz monophasic vs. 0.2Hz biphasic). Biphasic 1Hz or sham condition served as controls. The second experiment was to explore the effect of frequencies (0.2Hz vs. 0.8Hz) using the monophasic stimulation. Substhreshold TMS was applied 250 times over the left premotor cortex. Single photon emission computed tomography (SPECT) was performed before and after monophasic 0.2Hz or biphasic 1Hz rTMS.


RESULTS
Monophasic rTMS of both 0.2 and 0.8Hz significantly increased the ratio of N30 amplitudes as compared with sham rTMS, whereas biphasic stimulation showed no significant effects. SPECT showed increased rCBF in motor cortices after monophasic 0.2Hz rTMS, but not after biphasic 1Hz stimulation.


CONCLUSIONS
Monophasic rTMS exerted more profound effects on SEPs and rCBF than biphasic rTMS over the premotor cortex.


CONCLUSIONS
Monophasic rTMS over the premotor cortex could be clinically more useful than biphasic rTMS.
Department of Neurology, Institute of Health Biosciences, The University of Tokushima Graduate School, Kuramoto, Tokushima 770-8503, Japan.
Yuki
Y
Hosono
Ryo
R
Urushihara
Masafumi
M
Harada
Naomi
N
Morita
Nagako
N
Murase
Yamato
Y
Kunikane
Hideki
H
Shimazu
Kotaro
K
Asanuma
Haruo
H
Uguisu
Ryuji
R
Kaji
D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D013003:Somatosensory Cortex / Q000098:blood supply / Q000000981:diagnostic imaging / Q000502:physiology; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult