Recovery of swallowing after dysphagic stroke relates to functional reorganization in the intact motor cortex

Background & Aims: The aim of this study was to determine the mechanism for recovery of swallowing after dysphagic stroke. Methods: Twenty-eight patients who had a unilateral hemispheric stroke were studied 1 week and 1 and 3 months after the stroke by videofluoroscopy. Pharyngeal and thenar electromyographic responses to magnetic stimulation of multiple sites over both hemispheres were recorded, and motor representations were correlated with swallowing recovery. Results: Dysphagia was initially present in 71% of patients and in 46% and 41% of the patients at 1 and 3 months, respectively. Cortical representation of the pharynx was smaller in the affected hemisphere (5 +/- 1 sites) than the unaffected hemisphere (13 +/- 1 sites; P less than or equal to 0.001). Nondysphagic and persistently dysphagic patients showed little change in pharyngeal representation in either hemisphere at 1 and 3 months compared with presentation, but dysphagic patients who recovered had an increased pharyngeal representation in the unaffected hemisphere at 1 and 3 months (15 +/- 2 and 17 +/- 3 vs. 9 +/- 2 sites; P less than or equal to 0.02) without change in the affected hemisphere. In contrast, thenar representation increased in the affected hemisphere but not the unaffected hemisphere at 1 and 3 months (P less than or equal to 0.01). Conclusions: Return of swallowing after dysphagic stroke is associated with increased pharyngeal representation in the unaffected hemisphere, suggesting a role for intact hemisphere reorganization in recovery.