Remote effects of intermittent theta burst stimulation of the human pharyngeal motor system

Inflammation Sciences Research Group, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, UK.
European Journal of Neuroscience (Impact Factor: 3.18). 05/2012; 36(4):2493-9. DOI: 10.1111/j.1460-9568.2012.08157.x
Source: PubMed


Intermittent theta burst stimulation (iTBS) is a novel, non-invasive form of brain stimulation capable of facilitating excitability of the human primary motor cortex with therapeutic potential in the treatment of neurological conditions, such as multiple sclerosis. The objectives of this study were to evaluate the effects of iTBS on cortical properties in the human pharyngeal motor system. Transcranial magnetic stimulation (TMS)-evoked pharyngeal motor responses were recorded via a swallowed intra-luminal catheter and used to assess motor cortical pathways to the pharynx in both hemispheres before and for up to 90 min after iTBS in 15 healthy adults (nine male/six female, 22-59 years old). Active/sham iTBS comprised 600 intermittent repetitive TMS pulses, delivered in a double-blind pseudo-randomised order over each hemisphere on separate days at least 1 week apart. Abductor pollicis brevis (APB) recordings were used as control. Hemispheric interventional data were compared with sham using repeated-measures anova. iTBS was delivered at an average intensity of 43±1% of stimulator output. Compared with sham, iTBS to the hemisphere with stronger pharyngeal projections induced increased responses only in the contralateral weaker projection 60-90 min post-iTBS (maximum 54±19%, P≤0.007), with no change in stronger hemisphere responses. By contrast, iTBS to weaker projections had no significant effects (P=0.39) on either hemisphere. APB responses similarly did not change significantly (P=0.78) across all study arms. We conclude that iTBS can induce remote changes in corticobulbar excitability. While further studies will clarify the extent of these changes, iTBS holds promise as a potential treatment for dysphagia after unilateral brain damage.

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Available from: Emilia Michou, Sep 17, 2014
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    • "Visual feedback was provided on 50% of movements to assist in promoting performance gain. Following training, 600 pulses of iTBS [1] were administered (Magstim Super Rapid 2 stimulator with 70 mm figure-ofeight-coil ) at an intensity of 80% of active motor threshold over the motor hotspot (coil handle 45 ∘ to the midline) of the trained first dorsal interosseous (FDI) muscle (STIM group) or over the vertex (handle backwards) with the coil tilted by 90 ∘ (coil surface orthogonal to the scalp surface) with one side of the coil remaining in contact with the head [16] (SHAM group). Motor performance (peak acceleration in 10 test movements) and corticospinal excitability, assessed by eliciting MEPs in the trained, right FDI using 15 single pulse MEPs delivered at 130% of resting motor threshold (Magstim 200 2 , 70 mm figure-of-eight-coil; see [14] for more details), were measured before (i.e., pretest) and after motor training (but before iTBS) and again following iTBS. "
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