The impact of lesion location on dysphagia incidence, pattern and complications in acute stroke. Part 2: Oropharyngeal residue, swallow and cough response, and pneumonia

Abstract

Background and purpose: Dysphagia is a well-known complication of acute stroke. Given the complexity of cerebral swallowing control it is still difficult to predict which patients are likely to develop swallowing dysfunction based on their neuroimaging. In Part 2 of a comprehensive voxel-based imaging study, whether the location of a stroke lesion can be correlated with further dysfunctional swallowing patterns, pulmonary protective reflexes and pneumonia was evaluated.

Methods: In all, 200 acute stroke cases were investigated applying flexible endoscopic evaluation of swallowing within 96 h from admission. Lesions were mapped using patients' computed tomography/magnetic resonance images and these were registered to a standard space. The percentage of lesioned volume of 137 anatomically defined brain regions was determined on a voxel basis (FSL5.0). Region-specific odds ratios (ORs) were calculated with respect to the presence of oropharyngeal residue, delayed swallow response, insufficient cough reflex and occurrence of pneumonia during hospital stay. Colour-coded lesion location maps of brain regions with significant ORs were created (P < 0.05).

Results: Lesion maps for residue and impaired swallow response depicted parietal-temporal areas of the right hemisphere. Limbic structures in the right hemisphere and sensory regions on the left were associated with cough reflex disturbance. There was no overlap of lesion maps for impaired swallow response and insufficient cough reflex or pneumonia, but substantial overlap between the last two conditions.

Conclusions: This study gives new insights on the cortical representation of single components of swallowing and airway protection behaviours. The lesion model may help to risk-stratify patients for dysphagia and pneumonia based on their brain scan.

Keywords: cough reflex; dysphagia; endoscopic evaluation of swallowing; lesion analysis; neuroimaging; pneumonia; stroke.