BACKGROUND & AIMS: Excitatory
brain stimulation with
repetitive transcranial magnetic stimulation (rTMS) has been proposed as a treatment for
dysphagia after
stroke. Moreover, 1-Hz rTMS can induce a "virtual
lesion" in the human pharyngeal
motor cortex that suppresses
brain activity and temporarily disrupts swallowing. We thus examined if rTMS could reverse the disrupted
brain and swallowing functions following a unilateral virtual
lesion in the pharyngeal
motor cortex, such that rTMS might be developed as a therapy. METHODS: Healthy subjects (n = 23) were given varying conditions of 5-Hz rTMS over the pharyngeal
motor cortex to determine the most effective excitatory parameters. Thereafter, a unilateral virtual
lesion was made in the pharyngeal
motor cortex using 1-Hz rTMS, followed by
contralateral active or sham 5-Hz rTMS.
Motor evoked potentials and serial swallowing reaction times were recorded before and for 60 minutes postlesion to assess reversibility of the disruption to
the brain and swallowing. RESULTS: The greatest increase in pharyngeal
motor cortex excitability was seen following 250
pulses of 5-Hz rTMS (F(1,11) = 10.3, P = .008), an effect that lasted over 2 hours. In contrast to sham rTMS, active
contralateral 5-Hz rTMS completely abolished the cortical suppression induced by the virtual
lesion, with effects occurring for up to 50 minutes in both unlesioned (F(1,11) = 6, P = .03) and lesioned (F(1,11) = 67, P < .001) hemispheres. Active rTMS also reversed the changes in swallowing behavior (F(1,8) = 9, P = .018), restoring function to prelesional levels. CONCLUSIONS: Contralesional-targeted neurostimulation modulates
brain activity and swallowing motor behavior after experimental disruption and might be usefully applied in stroke-affected patients as a therapy for
dysphagia.
