Administering 10Hz cerebellar repetitive transcranial magnetic stimulation (rTMS) offers a “promising”, non-invasive treatment option in patients experiencing dysphagia following a subacute infratentorial stroke, as per the findings of a recent randomised controlled trial (RCT).
Writing in the journal Brain Stimulation, Zulin Dou, Hongmei Wen (both The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China) and colleagues state that, while this neuromodulation technique has the potential to increase corticobulbar tract excitability in healthy patients, its clinical efficacy for post-stroke dysphagia “remains unclear”.
In an attempt to investigate and elucidate this further, Dou, Wen and colleagues conducted a single-blinded RCT in which 42 post-stroke dysphagia patients with subacute infratentorial stroke were allocated into three groups: bilateral cerebellar rTMS (biCRB-rTMS), unilateral cerebellar rTMS (uniCRB-rTMS), or sham rTMS. They went on to investigate whether 10Hz rTMS with a double-cone coil applied to the cerebellar hemisphere for 10 days can improve swallowing function in patients with dysphagia after an infratentorial stroke, as well as exploring its possible influence on corticobulbar tract excitability.
Outlining the design of their study, the authors state that the stimulation parameters involved five trains of 50 stimuli at 10Hz with an interval of 10 seconds at 90% of the thenar resting motor threshold (RMT). And, regarding the endpoints of their study, they report functional oral intake scale (FOIS) scores as having been assessed at T0 (baseline), T1 (day 0 after intervention) and T2 (day 14 after intervention), while scores on the dysphagia outcome and severity scale (DOSS) and penetration aspiration scale (PAS)—as well as neurophysiological parameters—were evaluated at T0 and T1 only.
“Significant time and intervention interaction effects were observed for the FOIS score,” Dou, Wen and colleagues write, relaying their results. “The changes in the FOIS scores at T1 and T2 were both significantly higher in the biCRB-rTMS group than in the sham-rTMS group. The uniCRB-rTMS and biCRB-rTMS groups demonstrated greater changes in the DOSS and PAS at T1 compared with the sham-rTMS group.”
In addition, the authors state that bilateral corticobulbar tract excitability partly increased in the biCRB-rTMS and uniCRB-rTMS groups at T1, compared with T0, and that the percentage changes in corticobulbar tract excitability parameters at T1 “showed no difference among [the] three groups”.
Concluding their report, Dou, Wen and colleagues note that—from a clinical perspective—these RCT data provide “incremental evidence” that 10Hz rTMS over the bilateral cerebellar hemisphere is a promising, non-invasive treatment option in this patient population. They also posit that, in the study, corticobulbar tract excitability changed after combined treatments.
“However, it remains unclear whether these changes lead to treatment effects,” they add. “Future studies are required to confirm whether the current strategy is effective in a more extensive population that has suffered from stroke, and to explore the mechanisms underlying post-stroke dysphagia treatment by cerebellar rTMS.”
