Volume 115, Issue 5, Pages 1104-1112 (November 1998) Recovery of swallowing after dysphagic stroke relates to functional reorganization in the intact motor cortex  Shaheen Hamdy*,‡, Qasim Aziz*, John C. Rothwell‡, Maxine Power§, Krishna D. Singh∥, David A. Nicholson¶, Raymond C. Tallis#, David G. Thompson*  Gastroenterology  Volume 115, Issue 5, Pages 1104-1112 (November 1998) DOI: 10.1016/S0016-5085(98)70081-2 Copyright © 1998 American Gastroenterological Association Terms and Conditions

Fig. 1 Comparisons over time of the videofluoroscopic categories of swallowing function for each of the nondysphagic (○), recovered dysphagic (●), and persistent dysphagic (2) stroke patient groups. The number in parenthesis at the beginning of each line indicates the number of patients (>1) who had that particular swallowing outcome pattern. Most recovered dysphagic patients had attained normal swallowing function by 1 month, whereas all patients with severe dysphagia at 1 month remained dysphagic at 3 months. Gastroenterology 1998 115, 1104-1112DOI: (10.1016/S0016-5085(98)70081-2) Copyright © 1998 American Gastroenterological Association Terms and Conditions

Fig. 2 Mapped cortically evoked EMG responses recorded from the pharynx for a dysphagic patient recovering from a stroke at presentation, 1 month, and 3 months. Each grid pair represents the right and left hemispheres viewed from above, with the vertex marked with an X. Traces are shown only at the grid sites where an EMG response was obtained. Pharyngeal responses from the right hemisphere (unaffected) show a marked increase in both the amplitude and area of representation over time, whereas there is little change over the left hemisphere (affected). Gastroenterology 1998 115, 1104-1112DOI: (10.1016/S0016-5085(98)70081-2) Copyright © 1998 American Gastroenterological Association Terms and Conditions

Fig. 3 (A–C) Topographic maps of the pharynx for 3 patients who had a stroke at presentation, 1 month, and 3 months. Subject A was nondysphagic throughout the study, subject B was dysphagic at presentation but had recovered swallowing by 1 month, and subject C had persistent dysphagia throughout the study. Each pair of maps represent the right and left hemispheres viewed from above, with the position of the cranial vertex marked with an X. The affected hemisphere in each case is indicated by the grey frame. The scale represents the percentage maximum response amplitude in each subject. In A and C, there is little change in the pharyngeal representations in either hemisphere over time, whereas in B, marked reorganization of the pharyngeal representation can be seen in the unaffected hemisphere over time with little change in the affected hemisphere. Gastroenterology 1998 115, 1104-1112DOI: (10.1016/S0016-5085(98)70081-2) Copyright © 1998 American Gastroenterological Association Terms and Conditions

Fig. 4 (A–C) Topographic maps of the contralateral thenar muscles of 3 stroke patients at presentation, 1 month, and 3 months. Subject A (nondysphagic) and subject B (recovered from dysphagia) recovered well from hemiparesis, whereas subject C (persistently dysphagic) remained densely hemiplegic throughout. Each pair of maps represent the right and left hemispheres viewed from above, with the position of the cranial vertex marked with an X. The affected hemisphere in each case is indicated by a grey frame. Thenar representations show virtually no change in size in the unaffected hemisphere in all 3 subjects, but in subjects A and B it increases in the affected hemisphere over time, in association with improvement in limb function. Gastroenterology 1998 115, 1104-1112DOI: (10.1016/S0016-5085(98)70081-2) Copyright © 1998 American Gastroenterological Association Terms and Conditions

Fig. 5 Comparisons of the magnitude of representation in the (A) pharynx and (B) contralateral thenar muscles in stroke patients at presentation, 1 month, and 3 months. Affected and unaffected hemisphere group data (mean ± SEM) for nondysphagic (○), recovered dysphagic (•), and persistent dysphagic (2) patients. In the pharynx, the affected hemisphere shows little change in response over time in each 3 patient groups. By comparison, in the recovered dysphagic patients, the unaffected hemisphere representation increases at 1 and 3 months (P < 0.02), whereas these values are unchanged in nondysphagic patients and those with persistent dysphagia. In contrast, the thenar response magnitudes of representation increases in each of the patient groups in the affected hemisphere (P < 0.03). Gastroenterology 1998 115, 1104-1112DOI: (10.1016/S0016-5085(98)70081-2) Copyright © 1998 American Gastroenterological Association Terms and Conditions

Fig. 6 A series of left lateral oblique surface brain MRI images from a stroke patient onto which the pharyngeal and contralateral thenar topographic data (grey-toned areas, increasing from dark to light) have been coregistered. The patient, who had a left hemisphere cortical stroke affecting the lower sensorimotor cortex, was dysphagic at presentation but recovered swallowing by 1 month. It is evident that after the stroke, the representation of the pharynx in the anterior aspect of motor cortex and premotor areas expands anterolaterally in the right unaffected hemisphere at both 1 and 3 months, with little change in the affected left hemisphere. In contrast, the representation of the thenar muscles in superior motor cortex increases anteriorly and posteriorly in the affected left hemisphere over time, but remains unchanged in the unaffected right hemisphere. Gastroenterology 1998 115, 1104-1112DOI: (10.1016/S0016-5085(98)70081-2) Copyright © 1998 American Gastroenterological Association Terms and Conditions