Effects of High-Frequency Repetitive Transcranial Magnetic Stimulation on Cerebral Hemodynamics in Patients with Disorders of Consciousness: A Sham-Controlled Study

Abstract

Objective: This study aimed to determine the effects of high-frequency repetitive transcranial magnetic stimulation (rTMS) on cerebral hemodynamics in patients with disorders of consciousness (DOC). Methods: In this sham-controlled study, 20-Hz and sham rTMS were applied over the left primary motor cortex (M1) of 5 patients in a vegetative state (VS) and 5 patients in a minimally conscious state (MCS). The clinical behavior and cerebral blood flow (CBF) velocity in the bilateral middle cerebral artery (MCA) of the patients were evaluated before and after rTMS. Results: Compared with the VS group, the MCS group exhibited significant increases in peak systolic velocity (PSV; p = 0.024) and mean flow velocity (MFV) of the left MCA that were temporally related to the rTMS (p = 0.042). There were no significant effects on CBF velocity in the sham-stimulation group or the right MCA. Conclusions: High-frequency rTMS exerts different effects on CBF depending on the level of consciousness in patients with DOC such that it increased PSV and MFV in patients in a MCS. These effects may be related to the varying degrees of disrupted neurovascular coupling and the autonomic control of the cerebral hemodynamics in patients in a VS or MCS.