Effects of Low-Frequency Repetitive Transcranial Magnetic Stimulation Combined with Intensive Speech Therapy on Cerebral Blood Flow in Post-Stroke Aphasia

Abstract

We provided an intervention to chronic post-stroke aphasic patients using low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) guided by a functional magnetic resonance imaging (fMRI) evaluation of language laterality, combined with intensive speech therapy (ST). We performed a single photon emission-computed tomography (SPECT) scan pre- and post-intervention and investigated the relationship between cerebral blood flow (CBF) and language function. Fifty right-handed chronic post-stroke aphasic patients were enrolled in the study. During their 11-day hospital admission, the patients received a 40-min session of 1-Hz LF-rTMS on the left or right hemisphere, according to language localization identified by the fMRI evaluation, and intensive ST daily for 10 days, except for Sunday. A SPECT scan and language evaluation by the Standard Language Test of Aphasia (SLTA) were performed at the time of admission and at 3 months following discharge. We calculated laterality indices (LIs) of regional CBF (rCBF) in 13 language-related Brodmann area (BA) regions of interest. In patients who received LF-rTMS to the intact right hemisphere (RH-LF-rTMS), the improvement in the total SLTA score was significantly correlated with the pre- and post-intervention change of LI (ΔLI) in BA44. In patients who received LF-rTMS to the lesional left hemisphere (LH-LF-rTMS), this association was not observed. Analyses of the SLTA subscales and rCBF ΔLI demonstrated that in the RH-LF-rTMS group, the SLTA Speaking subscale scores were significantly correlated with ΔLIs in BA11, 20, and 21, and the SLTA Writing subscale scores were significantly correlated with ΔLIs in BA6 and 39. Conversely, in the LH-LF-rTMS group, the SLTA Speaking subscale scores were correlated with ΔLI in BA10, and the SLTA Reading subscale scores were significantly correlated with ΔLIs in BA13, 20, 22, and 44. Our results suggest the possibility that fMRI-guided LF-rTMS combined with intensive ST may affect CBF and contribute to the improvement of language function of post-stroke aphasic patients. LF-rTMS to the non-lesional and lesional hemispheres showed a difference in the associations between language performance and CBF. The results indicate that more effective rTMS intervention needs to be explored for patients who show right hemisphere language activation in an fMRI language evaluation.

The Effect of Selective Transcranial Magnetic Stimulation with Functional Near-Infrared Spectroscopy and Intensive Speech Therapy on Individuals with Post-Stroke Aphasia

“…Jennum et al administered rTMS to F7/8 and CP5/6 of the international 10-20 electrode system, postulating that these sites corresponded to the IFG and superior temporal gyrus respectively [14,15]. We also used this method in previous rTMS studies to prove the safety and efficacy of rTMS [8,9]. The probes were arranged so that F7/8 (IFG) of the international 10-20 electrode system corresponded to channels 5 and 30.…”

“…If a patient showed language activation in the left hemisphere, LFS was administered to their right hemisphere. This method aims to facilitate activity in the left language region based on the principle of interhemispheric inhibition [3,4,8,9]. Conversely, if a patient's language activation was in the right hemisphere, we administered HFS to the right hemisphere.…”

“…Conversely, if a patient's language activation was in the right hemisphere, we administered HFS to the right hemisphere. This is because our previous study showed limited efficacy of LFS to the left hemisphere in patients whose language activation was in the right hemisphere [9]. One session of 1-Hz LFS lasted for 40 min (2,400 total stimulations), and 1 session of 10-Hz HFS lasted for 12 min (2,400 total stimulations).…”

“…This is a treatment method that involves the identification of the language region using fMRI followed by LFS to the contralateral homologous regions based on the principle of interhemispheric inhibition, and which is combined with iST [8]. In addition, we have investigated the effects of selective LFS and iST on cerebral blood flow single photon emission computed tomography and reported the differential effects of LFS to the ipsi- and contralesional hemispheres on cerebral blood flow [9]. In that study, we reported a significant improvement of language function in response to LFS to the contralesional hemisphere and LFS to the ipsilesional hemisphere.…”

“…Near-infrared spectroscopy (NIRS) measures the wavelength and intensity of the absorption of near-infrared light by tissue [9]. NIRS can be used to probe brain function through an intact skull by detecting changes in blood hemoglobin concentrations associated with neural activity.…”