1-Hz Repetitive Transcranial Magnetic Stimulation Increases Cerebral Vasomotor Reactivity: A Possible Autonomic Nervous System Modulation

• Main Authors: Fabrizio Vernieri, Claudia Altamura, Paola Palazzo, Riccardo Altavilla, Emma Fabrizio, Rita Fini, Jean-Marc Melgari, Matteo Paolucci, Patrizio Pasqualetti, Paola Maggio
• Format: Article
• Language: English
• Published: Elsevier 2014-03-01
• Series: Brain Stimulation
• Subjects: Repetitive transcranial magnetic stimulation; Cerebral hemodynamics; Cerebral vasomotor reactivity; Transcranial Doppler
• Online Access: http://www.sciencedirect.com/science/article/pii/S1935861X13004075

Background: Neuromodulation techniques, i.e. repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), can modify cerebral hemodynamics. High frequency rTMS appeared to decrease cerebral vasomotor reactivity (VMR), while there is still poor evidence about the effect of low frequency (LF) rTMS on cerebral blood flow (CBF) and VMR. Hypothesis: The present study aimed to test if LF rTMS decreases CBF and increases cerebral VMR. Monolateral or bilateral hemispheric involvement and duration of the effect were considered. A possible role of autonomic nervous system in CBF and VMR modulation was also investigated. Methods: Twenty-four right-handed healthy subjects underwent randomly real (12) or sham (12) 20-min 1-Hz rTMS on left primary motor cortex. Mean flow velocity and VMR of middle cerebral arteries were evaluated by means of transcranial Doppler before (T0), after 10 min (T1) and after 2 (T2), 5 (T3) and 24 h (T4) from rTMS. Heart rate variability (HRV) was studied within the same timing interval, assessing low frequency/high frequency (LF/HF) ratio as index of autonomic balance. Results: After real rTMS compared with sham stimulation, MFV decreased bilaterally at T1 (F = 3.240, P = .030) while VMR increased bilaterally (F = 5.116, P = .002) for at least 5 h (T3). LF/HF ratio decreased early after real rTMS (F = 2.881, P = .040). Conclusion: 1-Hz rTMS may induce a bilateral long-lasting increase of VMR, while its effect on MFV is short-lasting. Moreover, HRV changes induced by rTMS suggest a possible autonomic nervous system modulation.